Note: Descriptions are shown in the official language in which they were submitted.
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ENERGY-EFFICIENT SYSTEMS INCLUDING VAPOR COMPRESSION
FOR BIOFUEL OR BIOCHEMICAL PLANTS
PRIORITY DATA
[0001] This international patent application claims priority to U.S.
Patent App.
No. 15/711,699, filed on September 21, 2017, which is hereby incorporated by
reference herein.
FIELD OF THE INVENTION
[0002] The present invention generally relates to processes, systems,
and
apparatus for recovery and refinement of bio-products from bio-fermentation
plants
requiring distillation.
BACKGROUND OF THE INVENTION
[0003] The process energy consumed in the distillation of bio-products
often
constitutes the largest energy requirement in the production life cycle of
those
products. Distillation systems are designed to meet a number of requirements
appropriate to the priorities existing when design and investment decisions
are made.
First-generation distillation systems were implemented when simplicity was
highly
prized and environmental concerns related to energy usage were largely
relegated to
minimizing associated hazardous emissions. Today, policies and regulatory
initiatives targeting the reduction of greenhouse gas emissions are impacting
consumers and producers of energy, creating incentives for improving energy
efficiency and minimizing environmental footprints.
[0004] Examples of regulation impacting energy consumers and producers
include California's Low Carbon Fuel Standard (LCFS) and the U.S. EPA's Clean
Power Plan. The LCFS models life cycle fuel pathways to assign a Carbon
Intensity
(CI) to fuels that reflects a fuel's carbon dioxide emissions. A fuel
producer's
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pathway, reflecting the CI for their process, generates credits or requires
the purchase
of credits from other producers to meet California's CI targets. These credits
are
traded on an exchange that establishes their value and permits monetization by
producers. Improvements in process energy efficiency are directly rewarded
through
the LCFS system, incentivizing energy efficiency investments. This system, and
similar systems under consideration by governmental authorities, directly
reward
producers for reducing their energy requirements, even when low energy prices
provide little or no incentive to make such investments.
[0005] Bio-fermentation products, which include biofuels, are the
result of the
investment of energy by growing a biological raw material which is then
converted by
chemical processing to a purified liquid fuel, with each step requiring energy-
intensive stages which include distillation. Conventional, first-generation
methods
employed at a bio-distillery plant expend significant energy in distillation
(including
distillation, evaporations, and possibly dehydrations) and drying. The
inefficiency of
these methods negatively impacts producer economics as well as the
environmental
footprint ascribed to the process.
[0006] Improvements in overall energy efficiency and optimization are
still
needed commercially for new or existing distilleries, or new or existing
biorefineries
employing distillation.
SUMMARY OF THE INVENTION
[0007] Some variations of the invention provide an energy-efficient
system
configured for a distillery or biorefinery, wherein the distillery or
biorefinery is
capable of converting biomass into a biofuel or biochemical, and wherein the
distillery or biorefinery includes a distillation unit configured for
distillation to purify
the biofuel or biochemical, the system comprising:
(i) a vapor compression sub-system comprising a mechanical vapor
recompression (MVR) unit and/or a thermal vapor recompression (TVR) unit,
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wherein the vapor compression sub-system is configured to recover latent heat
and
provide a reduction in process thermal energy usage in the distillery or
biorefinery;
and
(ii) an optional combined heat and power (CHP) sub-system having a CHP
engine, configured to provide mechanical, electrical, and/or thermal energy
for
driving the vapor compression sub-system, wherein when the CHP sub-system is
present, the CHP sub-system and the vapor compression sub-system are
integrated
and configured so that residual waste heat of the CHP engine offsets process
thermal
energy usage in the distillery or biorefinery.
[0008] In some
embodiments, the vapor compression sub-system comprises
multiple mechanical and/or thermal compressors or vapor jets, wherein cascaded
heat
to or from the distillation unit is integrated with multiple stillage
evaporations and/or
dehydration, and wherein compressed biofuel or biochemical vapors and
generated
steam are returned to the distillation unit within the system.
[0009] In some
embodiments, the vapor compression sub-system comprises
multiple mechanical and/or thermal compressors or vapor jets, wherein cascaded
heat
to or from the distillation unit is integrated with multiple stillage
evaporations
including a first or last multiple evaporator, wherein compressed steam from
the first
evaporator is optionally split between the distillation unit and a part of the
multiple
stillage evaporations, and wherein a compressor stage is configured to cascade
latent
heat between the distillation unit and the multiple stillage evaporations.
[0010] In some
embodiments, the vapor compression sub-system comprises
multiple mechanical and/or thermal compressors or vapor jets, wherein cascaded
heat
to or from multiple stillage evaporations to the distillation unit is
integrated with
compression of steam to or from at least one reboiler-evaporator to drive the
distillation and partial evaporation, and/or wherein compressor stages are
configured
to cascade the latent heat from the distillation process unit into an
evaporation unit.
[0011] In some
embodiments, the vapor compression sub-system comprises
multiple mechanical and/or thermal compressors or vapor jets, wherein cascaded
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latent heat from the distillation process unit is integrated to drive vapor-
phase
dehydration of a vapor stream output of the distillation unit.
[0012] In certain embodiments, the energy-efficient system comprises a
dryer
configured for drying stillage derived from the distillation unit, wherein the
vapor
compression sub-system comprises both an MVR unit configured to recover the
latent
heat of the distillation and a TVR unit configured to recover latent heat from
exhaust
gases from the dryer.
[0013] In these or other embodiments, the energy-efficient system
comprises a
dryer configured for drying stillage derived from the distillation unit,
wherein the
vapor compression sub-system comprises multiple mechanical and/or thermal
compressors or vapor jets, and wherein cascaded latent heat from an exhaust of
the
dryer, recaptured by a reboiler-evaporator, is integrated to provide steam for
other
plant processes.
[0014] The CHP sub-system is present within the energy-efficient
system, in
some variations of the invention. When the CHP sub-system is present, the CHP
engine may be sized in concert with energy demand of the vapor compression sub-
system and/or thermal energy demand of the distillery or biorefinery, wherein
waste
heat recovered by the CHP sub-system provides at least some of the thermal
energy
demand of the distillery or biorefinery.
[0015] In these or other embodiments in which the CHP sub-system is
present,
the vapor compression sub-system comprises a TVR unit, wherein the CHP engine
is
sized in concert with motive vapor demand of the TVR unit.
[0016] Other variations of the invention provide a method of modifying
a
distillery or biorefinery, wherein the distillery or biorefinery converts
biomass into a
biofuel or biochemical, and wherein the biofuel or biochemical is purified by
distillation, the method comprising:
(i) introducing a vapor compression unit comprising a mechanical vapor
recompression (MVR) unit and/or a thermal vapor recompression (TVR) unit to
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recover latent heat and provide a reduction in process thermal energy usage in
the
distillery or biorefinery; and
(ii) optionally introducing a combined heat and power (CHP) system having a
CHP engine, to provide mechanical, electrical, and/or thermal energy for
driving the
vapor compression unit, wherein when the CHP system is present, (a) residual
waste
heat of the CHP engine offsets process thermal energy usage in the distillery
or
biorefinery, in conjunction with the vapor compression unit, and (b)
integration of the
vapor compression unit with the CHP system is balanced to optimize process
energy
requirements, process carbon intensity, and/or process energy costs.
[0017] In some embodiments, the vapor compression unit comprises
multiple
mechanical and/or thermal vapor compressors or vapor jets, wherein cascaded
latent
heat from the distillation is integrated with multiple stillage evaporations
and/or
dehydration, and wherein compressed biofuel or biochemical vapors and
generated
steam are returned to the distillation.
[0018] In some embodiments, the vapor compression unit comprises
multiple
mechanical and/or thermal vapor compressors or vapor jets, wherein cascaded
latent
heat from the distillation is integrated with multiple stillage evaporations
including a
first evaporator, wherein compressed steam from the first evaporator is
optionally
split between the distillation and a part of the multiple stillage
evaporations, and
wherein the distillation and at least a portion of the multiple stillage
evaporations are
operated at equal or near-equal pressure, thereby allowing a compressor stage
to
cascade the latent heat of evaporation between the distillation and the
multiple stillage
evaporations and optionally vapor-phase dehydration.
[0019] In some embodiments, the vapor compression unit comprises
multiple
mechanical and/or thermal vapor compressors or vapor jets, wherein cascaded
latent
heat from multiple stillage evaporations to the distillation is integrated
with
compression of steam from at least one reboiler-evaporator to drive the
distillation
and partial evaporation, and wherein the distillation and the partial
evaporation are
operated such that evaporation pressure is higher than distillation pressure,
thereby
allowing compressor stages to cascade the latent heat of evaporation into the
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distillation. Optionally, compression of the distillation vapors is integrated
with
dehydration of distillation vapors at a sufficient pressure to generate a
final product
containing the biofuel or biochemical.
[0020] In some embodiments, the vapor compression unit is sized or
operated
with a standard steam generator for reduction of thermal energy required in
the
distillation, evaporation, and/or dehydration, wherein the standard steam
generator is
operated at a reduced rate as a result of reduction in steam energy demand due
to
energy recovered by the vapor compression unit.
[0021] When the CHP system is present, the CHP engine may be sized or
operated in concert with energy demand of the vapor compression unit and
thermal
energy demand of the distillery or biorefinery, wherein at least some of the
thermal
energy demand of the distillery or biorefinery is provided by waste heat
recovered by
the CHP system.
[0022] In certain embodiments in which the CHP system is present, the
vapor
compression unit comprises a TVR unit, and the CHP engine is sized or operated
in
concert with thermal energy demand for producing steam or biochemical motive
vapors to drive the TVR unit.
[0023] Integration of the vapor compression unit with the optional CHP
system allows balancing of use in the distillery or biorefinery of process
fuel energy,
electrical energy unit price, and process carbon intensity, wherein the
process energy
costs are minimized based on relative market pricing of the process fuel
energy and
the electrical energy, and optionally wherein total process energy is not
minimized.
[0024] In various embodiments, the biofuel or biochemical is selected
from
the group consisting of methanol, ethanol, 1-propanol, 2-propanol, n-butanol,
isobutanol, 2-butanol, tert-butanol, acetone, and combinations thereof.
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BRIEF DESCRIPTION OF THE FIGURES
[0025] Each of FIG. 1, FIG. 2, FIG. 3, FIG. 4, FIG. 5, FIG. 6, FIG. 7,
FIG. 8,
FIG. 9, and FIG. 10 is a schematic drawing, showing process flows for a
distillery or
biorefinery, with three hashed boxed areas. The first hashed line area is
labeled as
"Standard Distillery Section I", the second hashed line area is labeled as
"Compound
TVR-CHP Section II" or "Compound MVR-CHP Section II", without limitation
(Section II may also be referred to as "Compound MVR/TVR-CHP"), and the third
hashed line area is labeled as "Dryer Exhaust Heat MVR/TVR Section III",
"Dryer
Exhaust Heat TVR Section III", or "Dryer Exhaust Heat MVR Section III",
without
limitation. As explained below, any instance of MVR or TVR may be replaced by
TVR or MVR, respectively, in various embodiments.
[0026] Power used in driving vapor compression may be provided by
combined heat and power (CHP) or any other source of power including, but not
limited to, the utility grid, solar arrays, wind turbines, or other forms of
power
generation. Each of FIGS. 1 to 10 should be understood to represent this
optionality
of CHP. That is, while the drawings include CHP as being present, in
alternative
embodiments the CHP is replaced by (or augmented with) any other source of
heat
and/or power.
[0027] In FIGS. 1 to 10, Section I encompasses a distillery flow
diagram, and
Section II encompasses the added vapor compression (MVR and/or TVR) and the
optional CHP of variations of the invention. The schema splits Section I and
Section
II at the distillation tower, with standard steam-driven distillation on the
left side of
the tower in Section I and on the right side of the tower mechanical vapor
compression with the optional combined heat and power (MVR/TVR-CHP) in
Section II. Section III is split from Sections I and II at the dryer drum
having
MVR/TVR heat recovery from the exhaust gases.
[0028] FIG. 1 is a schematic drawing in which Section II depicts a
process
wherein the waste heat from the optional CHP is used to generate process steam
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through Heat Recovery for Steam Generation (HRSG), with the generated steam
being used to meet steam demands of the distillery.
[0029] FIG. 2 is a schematic drawing in which Section II depicts a
process in
which the waste heat from the optional CHP is used to generate process steam
through
Heat Recovery for Steam Generation (HRSG), with the generated steam being used
to
meet the steam demand of the distillery and with a portion of the optional CHP
waste
heat being used to directly dry the distillery co-products.
[0030] FIG. 3 is a schematic drawing in which Section II depicts a
process in
which the waste heat from the optional CHP is exclusively used to directly dry
the
distillery co-products.
[0031] FIG. 4 is a schematic drawing in which Section II depicts a
process in
which the waste heat from the optional CHP is used to generate process steam
by
Heat Recovery for Steam Generation (HRSG), with the generated steam used to
generate additional electrical power in a steam turbine to meet further
electrical
demand of the distillery or to sell onto the power grid. The low-pressure
steam
exiting the optional co-generation turbine is used as process steam to meet
the process
steam demand of the distillery.
[0032] FIG. 5 is a schematic drawing in which Section II depicts a
process in
which the distillation vapors are passed to a multi-effect evaporation process
with the
steam from the final effect compressed and passed to the distillation. This
integration
of vapor compression with evaporation together with the optional CHP is
implied for
the process configurations described in FIGS. 1, 2, 3, and 4.
[0033] FIG. 6 is a schematic drawing in which Section II depicts a
process by
which distillation vapors are passed to a multi-effect evaporation process
with the
biofuel or biochemical vapors condensing in the first effect. The produced
steam
passes to multiple compressor stages, with the first compressor stage intake
passing
from the lowest-pressure effect evaporator, passing steam on to another effect
where
it is compressed and passes to the later evaporators and the distillation
process. In the
distillation process, the pressure of the distillation and the high-pressure
evaporation
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effect are preferably operated at a common pressure, allowing one common
compressor. This integration of vapor compression with evaporation is implied
for
the process configurations described in FIGS. 1, 2, 3, and 4.
[0034] FIG. 7 is a schematic drawing in which Section II depicts a
process by
which the evaporation-generated steam vapors are passed into the distillation
to drive
the distillation process, with the resulting alcohol vapors being condensed in
the
condenser of Section I or passing to the vapor compression of Section II. The
evaporator steam passes to compressor stages, with the steam in the compressor
stage
intake coming from the effect of the evaporator, and the higher-pressure
output steam
of the compressor passing part of the steam back to the evaporator effect and
part to
the distillation. The biofuel/biochemical vapors of the distillation process
are passed
to the intake of a compressor with the higher-pressure biofuel/biochemical
vapors
passing to a reboiler/evaporator and the generated steam passing to the
distillation. In
the distillation process, the pressure of the distillation and the high-
pressure
evaporation effect are operated preferably with the distillation at lower
pressure than
the evaporation, allowing the distillation alcohol compressed vapor pressure
output
and the evaporator steam compressed vapor output to have a common pressure to
drive the distillation. This integration of distillation vapor compression
with
evaporation vapor compression is implied for the process configurations
together with
optional CHP as described in FIGS. 1, 2, 3, and 4.
[0035] FIG. 8 is a schematic drawing in which Section II depicts a
process by
which the azeotrope vapors from a two-phase distillation system are being
condensing
in the condenser of Section I or passing to the vapor compression of Section
II. The
azeotrope biofuel/biochemical vapors from the two-phase distillation pass into
the
compressor stages intake, and the higher-pressure output vapors of the
compressors
pass in part to the condensing side of a reboiler/evaporator which generates
steam for
the aqueous tower and the other part of the two-phase distillation. The
remaining
biofuel/biochemical vapors of the distillation process pass to the intake to a
compressor, resulting in an output of higher-pressure biofuel/biochemical
vapors
passing to a second reboiler/organic vaporizer, wherein the generated organic
vapors
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pass to the organic distillation tower. This integration of two-phase
distillation with
vapor compression driving a reboiler/evaporation for the aqueous distillation
and
vapor compression also driving the reboiler/organic vaporizer is implied for
the
process configurations together with optional CHP as described in FIGS. 1, 2,
3, and
4.
[0036] FIG. 9 is a schematic drawing in which Section II depicts a
process by
which distillation vapors are passed to a vapor compression system, where a
portion
of the compressed distillation top product vapors pass to a multi-effect
evaporation
process with the azeotrope biofuel or biochemical vapors condensing. The
generated
steam is returned to the distillation and the remaining vapors further
compressed to
the dehydration system, wherein the condensation of the biofuel/biochemical
generated steam is returned to drive the biorefinery or distillery. This
integration of
distillation vapor compression with dehydration vapor compression is implied
for the
process configurations described in FIGS. 1, 2, 3, 4, 5, 6 and 7.
[0037] FIG. 10 is a schematic drawing in which Section III depicts a
process
by which a portion of the sensible heat and condensable water vapors from the
wet
cake (stillage) dryer exhaust heat is recaptured to a reboiler-evaporator
where the
steam passes to a vapor compression system. The compressed steam from the
reboiler-evaporator may then be passed to other plant processes. The optional
integration of dryer exhaust heat recapture through vapor compression is
implied for
the process configurations described in FIGS. 1, 2, 3, 4, 5, 6, 7, 8, and 9.
[0038] These and other embodiments, features, and advantages of the
present
invention will become more apparent to those skilled in the art when taken
with
reference to the following detailed description.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0039] Certain embodiments of the present invention will now be
further
described in more detail, in a manner that enables the claimed invention so
that a
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person of ordinary skill in this art can make and use the present invention.
All
references herein to the "invention" shall be construed to refer to non-
limiting
embodiments disclosed in this patent application.
[0040] Unless otherwise indicated, all numbers expressing conditions,
concentrations, yields, and so forth used in the specification and claims are
to be
understood as being modified in all instances by the term "about."
Accordingly,
unless indicated to the contrary, the numerical parameters set forth in the
following
specification and attached claims are approximations that may vary depending
at least
upon the specific analytical technique. Any numerical value inherently
contains
certain errors necessarily resulting from the standard deviation found in its
respective
testing measurements.
[0041] As used in this specification and the appended claims, the
singular
forms "a," "an," and "the" include plural referents unless the context clearly
indicates
otherwise. Unless defined otherwise, all technical and scientific terms used
herein
have the same meaning as is commonly understood by one of ordinary skill in
the art
to which this invention belongs. If a definition set forth in this section is
contrary to
or otherwise inconsistent with a definition set forth in patents, published
patent
applications, and other publications that are incorporated by reference, the
definition
set forth in this specification prevails over the definition that is
incorporated herein by
reference.
[0042] The term "comprising," which is synonymous with "including,"
"containing," or "characterized by" is inclusive or open-ended and does not
exclude
additional, unrecited elements or method steps. "Comprising" is a term of art
used in
claim language which means that the named claim elements are essential, but
other
claim elements may be added and still form a construct within the scope of the
claim.
[0043] As used herein, the phrase "consisting of' excludes any
element, step,
or ingredient not specified in the claim. When the phrase "consists of' (or
variations
thereof) appears in a clause of the body of a claim, rather than immediately
following
the preamble, it limits only the element set forth in that clause; other
elements are not
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excluded from the claim as a whole. As used herein, the phrase "consisting
essentially of' limits the scope of a claim to the specified elements or
method steps,
plus those that do not materially affect the basis and novel characteristic(s)
of the
claimed subject matter.
[0044] With respect to the terms "comprising," "consisting of," and
"consisting essentially of," where one of these three terms is used herein,
the
presently disclosed and claimed subject matter may include the use of either
of the
other two terms. Thus in some embodiments not otherwise explicitly recited,
any
instance of "comprising" may be replaced by "consisting of' or, alternatively,
by
"consisting essentially of."
[0045] The concept of vapor compression in distillation has been
deployed in
reducing process requirements in refining for many decades. It has also been
widely
deployed in water desalination and process evaporation. This method of energy
recovery has been rarely utilized, however, in the distillation processes of
bio-
fermentation producers. In addition, the option of combined heat and power
(CHP)
has not been widely used in biofuels distilleries as advances in process
design have
significantly reduced producers' electrical demand to about one-fifth of the
total
processing energy, reducing incentives.
[0046] In this specification, "MVR" means mechanical vapor
recompression
and "TVR" means thermal vapor recompression. "MVR/TVR" means MVR and/or
TVR. All instances of "vapor compression," "vapor recompression," MVR, TVR,
MVR/TVR, and the like mean mechanical vapor recompression, thermal vapor
recompression, or a combination thereof Thermal vapor recompression may also
be
referred to as thermocompression or steam compression.
[0047] Some variations of the invention are premised on the
realization that
the energy consumed in bio-fermentation distillation can be reduced by process
and
system configurations that recycle distillation heat through the application
of vapor
compression and combined heat and power methods as disclosed herein. The
combination of vapor compression and combined heat and power is preferably
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configured as a fully redundant retrofit that leverages existing process
equipment
investment. Compression reduces the total thermal process energy requirement
of the
plant via recovering the otherwise rejected heats of vaporization, and the
mechanical
energy required in mechanical compression and/or thermal energy required in
thermal
compression can be optionally provided from combined heat and power methods.
Electrical energy and waste heat of the optional combined heat and power
system can
be used to offset the plant's electrical demand and process thermal energy
requirements.
[0048] The invention relates to the combination of distillation,
compression,
and optionally combined heat and power methods, wherein the total reduction of
the
purchased electrical and thermal process energy can be optimized through
balancing
energy usage and conversions, in a manner that minimizes the production energy
usage, cost, and environmental impact per gallon of product generated. The
ratio of
process electrical energy purchased from a power provider or provided through
self-
generation and the process thermal energy fuel purchased from a supplier may
be
managed through accounting for the costs of each form of energy relative to
the
production cost and reduction in usage available from the invention. The
invention
provides the option of varying the amount of electrical power generated
through the
optional combined heat and power process to optimize process efficiency using
electrical power purchases or self-generation to provide shortfalls or cyclic
demands
that either exceed the plant's capacity or impose inefficiencies that justify
such
purchases. The waste heat of a combined heat and power system may be passed as
recaptured heat to processes within and outside of the distillation stage.
[0049] The invention may, in some instances, utilize provided power
and
augment or eliminate the optional CHP system. Provided power that is produced
as a
byproduct of another process or system, or power that better satisfies
environmental
goals, for example, may be used and the efficiency and cost effectiveness of a
CHP
system foregone in favor of other benefits. For example, limits on emissions
may
favor solar, wind, or utility grid provided power. In some cases, very low
cost utility
grid power that is competitive with CHP power generation costs and reduces the
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capital costs of the project by eliminating the need for CHP may better meet
project
economic goals. Minimizing carbon intensity may favor powering the vapor
compression with renewable, low carbon-intensity power generation options.
[0050] The meaningful and sizable reduction in process thermal energy
usage
of these plants through addition of the invention will also substantially
reduce the
carbon intensity ascribed to the plant's process. The distillation energy in a
standard
bio-fermentation distillery without mechanical vapor compression represents
from
40% to 60% of the total process energy. Mechanical vapor compression, when
used
in distillation, evaporation, dehydration, and drying, recycles latent heat by
a closed
heat pump, as disclosed for example in U.S. Patent Nos. 4,340,446, 4,422,903,
4,539,076, 4,645,569, 4,692,218, 4,746,610, 5,294,304, 7,257,945, 8,101,217,
8,101,808, 8,114,255, 8,128,787, 8,283,505, 8,304,588, 8,535,413, and
8,614,077,
which are hereby incorporated by reference herein. Thermal vapor compression,
when used in distillation, evaporation, dehydration, and drying, recycles
latent heat by
a closed heat pump, as disclosed for example in U.S. Patent Nos. 5,772,850,
4,536,258, and 4,585,523, which are hereby incorporated by reference herein.
[0051] Distillation is generally the largest consumer of energy in a
plant
utilizing bio-fermentation due to the necessarily dilute beer produced by
micro-
organisms. The large amount of water in the beer must be separated from the
desired
product through distillation. Generally, the distillation system is heated by
steam
produced from combusting a fuel in a boiler. Vapors collected from the
distillation
system are cooled in a condenser where they release their latent heat of
condensation.
This energy is lost to the condenser's cooling water that, in turn, releases
its heat to
the atmosphere. By rerouting the vapors prior to their introduction into the
condenser
and increasing the pressure and temperature of the vapors through compression,
forcing the superheated vapors to condense in a reboiler, the latent heat of
condensation can be captured and transferred to water used to generate steam.
This
generated steam from the reboiler can be directly recycled to the distillation
tower, as
described in FIGS. 1, 2, 3, and 4.
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[0052] In some
embodiments, the generated steam from the reboiler may be
used to drive an evaporation system wherein pressure drops within the
evaporation
effects may require additional compression as described in FIG. 5. In some
embodiments, the evaporation and distillation may be driven from a common
compression system, passing steam to an evaporator operated at a common
pressure
with the distillation as described in FIG. 6. In some embodiments, the
distillation
compressor vapors pass to the reboiler as part of the evaporation, passing
steam back
to the distillation and the evaporation passing steam to the distillation as
in FIG. 7. In
some embodiments the distillation vapors are partially condensed in the
reboiler with
the remaining vapors compressed for vapor-phase dehydration with the anhydrous
vapor product of dehydration condensing in a reboiler with the generated steam
passed back to the distillery or bio-refinery. In some embodiments, two-phase
distillation compressor azeotrope vapors are balanced between two reboilers
with a
portion of the vapors condensing in one reboiler for water, which generates
steam for
driving the aqueous distillation tower, and the remaining compressed vapors
passing
to another reboiler for the organic alcohol to condense by producing organic
vapors
for driving the organic distillation tower as in FIG. 8.
[0053] In the
past, the high cost of driving the vapor compressor limited the
economic advantages that could be gained. More efficient motors with
integrated
heat recapture used for generating electricity to drive electric compressor
drive motors
or directly driving the compressor have become available, vastly improving
process
cost and efficiency. Using steam from an existing steam generation system to
supplant steam generated through vapor compression can allow the motors to
increase
their time operating at peak efficiency and provide motive vapors for driving
thermal
vapor compression. Electricity provided by excess generation not needed for
vapor
compression can replace electricity formerly supplied by a utility and motor
heat
recapture can provide additional process heat. Optimizing the efficiency of
the
motors and using system steam and utility electricity or power provided by any
other
means to trim output can achieve an optimized system configuration that
minimizes
total energy usage, cost, and carbon dioxide emissions. System reliability is
improved
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through retention of the existing steam generation and distillation system
that can be
operated during maintenance of the retrofit vapor compression system.
[0054] In a system utilizing mechanical vapor compression, the
mechanical
energy of the compression is typically equivalent to about 15% to 20% of the
thermal
energy required for the identical distillation process without compression.
The energy
advantage in mechanical vapor compression will be typically about 5:1, or in
various
embodiments, about 3:1, 4:1, 5:1, 6:1, 7:1 or higher. The market values of
thermal
energy and electricity vary by market with electrical power costs and natural
gas
thermal energy costs showing a historic cost relationship per unit of energy
of 3:1 to
8:1. The relative unit energy price relationship between thermal energy and
electrical
power determines the economic value of mechanical compression in distillation,
evaporation, dehydration, and drying. The investment costs of compression
equipment are an additional determinant of the economic advantage of
mechanical
vapor compression versus thermal vapor compression or standard distillation.
High
electrical costs for driving the mechanical compression system may outweigh
the
savings provided by reduced thermal energy demand. Lower capital costs and low
thermal energy costs may favor thermal vapor compression.
[0055] In a system utilizing thermal vapor compression, the thermal
energy of
the compression is typically equivalent to about 40% to 70% of the thermal
energy
required for the identical distillation process without vapor compression. The
energy
advantage in thermal vapor compression will be typically about 1.5:1, or in
various
embodiments, about 1.1:1, 1.2:1, 1.3:1, 1.4:1 or higher.
[0056] The typically high ratio of electrical power costs per unit
energy to
thermal natural gas costs per unit energy supports the use of high efficiency
combined
heat and power in bio-fermentation distillery processing. Electricity can
often be
generated at a lower cost than the price of power available from local utility
providers, and waste heat from the engine is easily directed into the many
processes
within the plant that require thermal energy not included in the distillation
stage.
Recently, advances in renewable power generation technologies have encouraged
the
use of solar and wind generated electricity, as well as waste to energy
technologies
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like gasification and anaerobic digestion, providing options for powering
vapor
compression systems that may have cost and environmental advantages relative
to
more traditional power generation technology.
[0057] In preferred embodiments, the invention integrates the
advantage
provided by reducing the cost of mechanical energy through use of the combined
heat
and power system with the reduced thermal energy required in the distillation
system
achieved by mechanical vapor compression. The design's optimization is
balanced
between current energy pricing and expected future trends in energy pricing
and
environmental regulation. The invention's focus on integration of mechanical
vapor
compression in distillation, evaporation, dehydration, and drying and combined
heat
and power provides multiple options for the design and sizing of the major
components and uses of the waste heat from the combined heat and power.
Several
examples are provided to demonstrate possible configurations of the integrated
system
utilizing mechanical vapor compression in distillation, evaporation,
dehydration, and
drying and combined heat and power.
[0058] Some variations of the present invention provide a method of
modifying a distillery or biorefinery, wherein the distillery or biorefinery
converts
biomass into a biofuel or biochemical, and wherein the biofuel or biochemical
is
purified by distillation, the method comprising:
(i) introducing a vapor compression unit comprising a mechanical vapor
recompression (MVR) unit and/or a thermal vapor recompression (TVR) unit to
recover latent heat and provide a reduction in process thermal energy usage in
the
distillery or biorefinery; and
(ii) optionally introducing a combined heat and power (CHP) system having a
CHP engine, to provide mechanical, electrical, and/or thermal energy for
driving the
vapor compression unit, wherein residual waste heat of the CHP engine offsets
the
process thermal energy usage in the distillery or biorefinery,
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wherein integration of the vapor compression unit with the optional CHP
system is balanced to optimize process energy requirements, process carbon
intensity,
and/or process energy costs.
[0059] Some variations of the present invention provide a method of
modifying a distillery or biorefinery, wherein the distillery or biorefinery
converts
biomass into a biofuel or biochemical, and wherein the biofuel or biochemical
is
purified by distillation, the method comprising:
(i) introducing a mechanical vapor recompression (MVR) unit to recover
latent heat and provide a reduction in process thermal energy usage in the
distillery or
biorefinery;
(ii) introducing a thermal vapor recompression (TVR) unit to further recover
latent heat and provide a further reduction in process thermal energy usage in
the
distillery or biorefinery; and
(ii) optionally introducing a combined heat and power (CHP) system having a
CHP engine, to provide mechanical and electrical energy for driving the MVR
unit
and thermal energy for driving the TVR unit, wherein residual waste heat of
the CHP
engine (when the CHP system is present) offsets the process thermal energy
usage in
the distillery or biorefinery,
wherein integration of the MVR and TVR units with the optional CHP system
is balanced to optimize process energy requirements, process carbon intensity,
and/or
process energy costs.
[0060] In some embodiments, the vapor compression unit comprises
multiple
mechanical or thermal vapor compressors, wherein cascaded heat from the
distillation
is integrated with multiple stillage evaporations, and wherein compressed
biofuel or
biochemical vapors and generated steam are returned to the distillation.
[0061] In some embodiments, the vapor compression unit comprises
multiple
mechanical or thermal vapor compressors, wherein cascaded heat from the
distillation
is integrated with multiple stillage evaporations including a first
evaporator, wherein
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compressed steam from the first evaporator is optionally split between the
distillation
and a part of the multiple stillage evaporations, and wherein the distillation
and at
least a portion of the multiple stillage evaporations are operated at equal or
near-equal
pressure, thereby allowing a compressor stage to cascade heat of evaporation
between
the distillation and the multiple stillage evaporations.
[0062] In some embodiments, the vapor compression unit comprises
multiple
mechanical or thermal vapor compressors and/or a TVR unit comprising multiple
vapor jets, wherein cascaded heat from multiple stillage evaporations to the
distillation is integrated with compression of steam from at least one
reboiler-
evaporator (e.g., from two or more reboiler-evaporators whose output is
combined) to
drive the distillation and partial evaporation, wherein the distillation and
the partial
evaporation are operated such that evaporation pressure is higher than
distillation
pressure, thereby allowing compressor stages to cascade the heat of
evaporation into
the distillation.
[0063] In some embodiments, the vapor compression unit comprises
multiple
mechanical or thermal vapor compressors, wherein cascaded heat from the
distillation
is partially recompressed to a reboiler where the condensed distillation top
product is
recovered for reflux and the remaining vapors are passed to the dehydration,
with the
pressure of the vapors being sufficient (optionally, additional compressors
are used) to
raise the pressure as needed to drive the dehydration.
[0064] The vapor compression unit may be sized or operated with a
standard
steam generator to reduce thermal energy required in the distillation, and
wherein the
standard steam generator is operated at a reduced rate as a result of
reduction in steam
energy demand due to energy recovered by the vapor compression unit.
[0065] The optional CHP engine may be sized or operated in concert
with (i)
mechanical demand of the MVR unit, if present; (ii) thermal demand of the TVR
unit,
if present; and (iii) thermal energy demand of the distillery or biorefinery.
When a
TVR unit is present, at least some of the thermal energy demand of the TVR
unit and
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distillery or biorefinery is optionally provided by waste heat recovered by
the CHP
system.
[0066] The integration of the vapor compression unit with the optional
CHP
system allows balancing of use in the distillery or biorefinery of process
fuel energy
and electrical energy unit price. For example, process energy costs may be
minimized
based on relative market pricing of the process fuel energy and the electrical
energy.
Optionally, total process energy is not minimized.
[0067] The integration of the vapor compression unit with the optional
CHP
system allows minimization of carbon intensity of the distillery or
biorefinery through
selective usage of electricity and thermal fuel to minimize total carbon
intensity of
process energy. In some embodiments, process energy costs are not minimized
based
on relative market pricing of the process fuel energy and the electrical
energy and the
individual carbon intensities allocated to thermal and electrical process
energy
lifecycles.
[0068] The present invention also provides a process comprising, or
adapted
for, any of the disclosed methods. The biofuel or biochemical may be selected
from
the group consisting of methanol, ethanol, 1-propanol, 2-propanol, n-butanol,
isobutanol, 2-butanol, tert-butanol, acetone, and combinations thereof The
biofuel or
biochemical may also be selected from organic acids, such as lactic acid,
higher
alcohols (e.g., C5+ alcohols), alkanes, etc. As used herein, "biofuel,"
"biochemical,"
biofuel/biochemical" and the like shall refer to one or more fermentation
products of
interest. Co-products include, but are not limited to, DDG, DDGS, sugars,
lignin, still
bottoms, and energy.
[0069] In addition, the present invention provides systems configured
to carry
out the disclosed methods. Some variations provide a distillery or biorefinery
comprising such a system. The system may be a retrofit to an existing plant.
In other
embodiments, the biorefinery is a greenfield plant.
[0070] In various embodiments, the biomass feedstock may be selected
from
agricultural crops and/or agricultural residues. In some embodiments,
agricultural
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crops are selected from starch-containing feedstocks, such as corn, wheat,
cassava,
rice, potato, millet, sorghum, or combinations thereof. In some embodiments,
agricultural crops are selected from sucrose-containing feedstocks, such as
sugarcane,
sugar beets, or combinations thereof.
[0071] Lignocellulose biomass may also be used as the biomass
feedstock.
Lignocellulose biomass includes, for example, plant and plant-derived
material,
vegetation, agricultural waste, forestry waste, wood waste, paper waste,
animal-
derived waste, poultry-derived waste, and municipal solid waste. In various
embodiments of the invention, the biomass feedstock may include one or more
materials selected from: timber harvesting residues, softwood chips, hardwood
chips,
tree branches, tree stumps, knots, leaves, bark, sawdust, off-spec paper pulp,
cellulose, corn, corn stover, wheat straw, rice straw, sugarcane bagasse,
switchgrass,
miscanthus, animal manure, municipal garbage, municipal sewage, commercial
waste,
grape pumice, almond shells, pecan shells, coconut shells, coffee grounds,
grass
pellets, hay pellets, wood pellets, cardboard, paper, carbohydrates, plastic,
and cloth.
Mixtures of starch-containing and/or sucrose-containing feedstocks with
cellulosic
feedstocks, for example, may be used.
[0072] Some variations provide an energy-efficient system configured
for a
distillery or biorefinery, wherein the distillery or biorefinery is capable of
converting
biomass into a biofuel or biochemical, and wherein the distillery or
biorefinery
includes distillation configured to purify the biofuel or biochemical, the
system
comprising:
(i) a vapor compression unit comprising a mechanical vapor recompression
(MVR) sub-system and/or a thermal vapor recompression (TVR) sub-system
configured to recover the latent heat in distillation, evaporation,
dehydration, and/or
drying and to provide a reduction in process thermal energy usage in the
distillery or
biorefinery; and
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(ii) optionally a combined heat and power (CHP) sub-system having a CHP
engine, configured to provide mechanical, electrical, and /or thermal energy
for
driving the vapor compression unit,
wherein the optional CHP sub-system and the vapor compression unit are
integrated and configured so that residual waste heat of the CHP engine
offsets
process thermal energy usage in the distillery or biorefinery.
[0073] Some variations provide an energy-efficient system configured
for a
distillery or biorefinery, wherein the distillery or biorefinery is capable of
converting
biomass into a biofuel or biochemical, and wherein the distillery or
biorefinery
includes distillation configured to purify the biofuel or biochemical, the
system
comprising:
(i) a mechanical vapor recompression (MVR) sub-system configured to
recover latent heat in distillation, evaporation, dehydration, and/or drying
and to
provide a reduction in process thermal energy usage in the distillery or
biorefinery;
(ii) a thermal vapor recompression (TVR) sub-system configured to recover
latent heat in distillation, evaporation, dehydration, and/or drying and to
provide a
further reduction in process thermal energy usage in the distillery or
biorefinery; and
(iii) optionally a combined heat and power (CHP) sub-system having a CHP
engine, configured to provide mechanical and electrical energy for driving the
MVR
unit and thermal energy for driving the TVR unit, wherein the optional CHP sub-
system with MVR and TVR units are integrated and configured so that residual
waste
heat of the CHP engine offsets process thermal energy usage in the distillery
or
biorefinery.
[0074] In some embodiments, the vapor compression unit comprises
multiple
MVR and/or TVR compressors, wherein cascaded heat from the distillation is
integrated with multiple stillage evaporations, and wherein compressed biofuel
or
biochemical vapors and generated steam are returned to the distillation within
the
system.
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[0075] In certain embodiments, the vapor compression unit comprises
multiple MVR and/or TVR compressors , wherein cascaded heat from the
distillation
is integrated with multiple stillage evaporations including a first
evaporator, wherein
compressed steam from the first evaporator is optionally split between the
distillation
and a part of the multiple stillage evaporations, and wherein a compressor
stage is
configured to cascade heat of evaporation between the distillation and the
multiple
stillage evaporations.
[0076] In some embodiments, the vapor compression unit comprises
multiple
MVR and/or TVR, wherein cascaded heat from multiple stillage evaporations to
the
distillation is integrated with compression of steam from at least one
reboiler-
evaporator to drive the distillation and partial evaporation, and wherein
compressor
stages are configured to cascade the heat of evaporation into the
distillation.
[0077] An MVR unit may be configured with a standard steam generator
to
reduce thermal energy required in the distillation. The optional CHP engine
may be
sized in concert with (i) mechanical demand of the MVR unit and (ii) thermal
energy
demand of the distillery or biorefinery. The waste heat recovered by a CHP
system
optionally provides at least some of the thermal energy demand of the
distillery or
biorefinery, and may drive an optional TVR unit when present in conjunction
with the
MVR unit.
[0078] A TVR unit may be configured with a standard steam generator to
reduce thermal energy required in the distillation. The optional CHP engine
may be
sized in concert with (i) thermal demand of the TVR unit and (ii) thermal
energy
demand of the distillery or biorefinery. The waste heat recovered by a CHP
system
optionally provides at least some of the motive vapor to drive a TVR vapor jet
and/or
provide thermal energy demand of the distillery or biorefinery.
[0079] The terms "distillery," "distillery process," and "distillery
plant" herein
refer to a bio-fermentation plant or process in which raw biomass is processed
through stages leading to a fermentation stage and on to separation of the
fermentation products using distillation separation, evaporation, and
dehydration as at
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least one stage for product purification. The term "biorefinery" herein refers
to a
plant or process in which raw biomass is processed through stages leading to a
fermentation stage and on to separation of the fermentation products using
distillation
separation as at least one stage for product purification, wherein the
fermentation
product may be any biofuel or biochemical, and wherein the biomass feedstock
may
be lignocellulosic biomass. All instances of "distillery" in this
specification may be
replaced with "biorefinery," and vice-versa, in some embodiments.
[0080] The term "total process energy" herein refers to the thermal
energy
required to raise process steam by burning fuels, or direct heating of
processes by
burning fuels, plus the electrical energy required for mechanical power used
in
pumping, stirring, grinding, etc.
[0081] The terms "addition of mechanical vapor compression in
distillation,
evaporation, dehydration, and drying" and "addition of combined heat and
power"
herein refer to a retrofit or augmentation of a standard distillery or
biorefinery that
uses a standard thermally driven distillation process, to a distillery or
biorefinery
enhanced with the option of diverting vapors into a mechanical vapor
compression
system integrated into the distillery or biorefinery, including a combined
heat and
power system.
[0082] The terms "mechanical vapor compression in distillation,
evaporation,
dehydration, and drying", "thermal vapor compression in distillation,
evaporation,
dehydration, and drying" and "integrated combined heat and power" herein refer
to
the addition of mechanical vapor compression, vapor jet compression and
combined
heat and power, respectively, to provide the ability to operate with various
combinations of mechanical vapor compression and/or thermal vapor compression,
standard process steam generated by the original system, and combined heat and
power to receive the maximum advantage from each of the added processes (i.e.,
mechanical vapor compression and/or thermal vapor compression in distillation,
evaporation, dehydration, and drying, and combined heat and power).
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[0083] The terms "bio-fermentation distillery process stages," as
found in
each of the schematic flow diagrams (FIGS. 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10)
herein,
refer generally to stages 1 through 9 as follows:
[0084] Stage 1: A milling stage or device(s) which process biomass by
physically dividing the feedstock materials with a grinding or extrusion
process which
exposes the internal parts of the feedstock;
[0085] Stage 2: A cooking stage which uses various combinations of
controlled temperatures, pressures, stirring, and special chemical
conditioning with
acidic or basic chemicals, and/or enzymes (e.g., amylase or cellulase
enzymes), for
breaking polysaccharides into glucosides;
[0086] Stage 3: A heat exchanger stage which cools the cook solution
to
fermentation temperatures and conversely heats post-fermentation products up
to
distillation temperatures;
[0087] Stage 4: A fermentation stage wherein the cook solution has
biological
agents introduced to ferment the sugars to the desired biochemical product(s);
[0088] Stage 5: A distillation stage, after the fermented products
have been
pre-heated in the heat exchanger of stage 3, where the biochemical top
products are
separated from the fermentation waters;
[0089] Stage 6: A condensation stage where the vapors from the
distillation
stage 5 are passed on to a cooling system where the latent heat is discarded,
or where
the vapors are mechanically compressed to recover the latent heat and cascade
the
heat to, or from, stages 7 and stage 8 ;
[0090] Stage 7: A stillage handling stage for the bottom product of
the
distillation or aqueous distillation stage 5, for recovering wet co-products
of the
fermentation to be further processed with possible drying and, potentially,
evaporation
to concentrate thin stillage;
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[0091] Stage 8: An optional dehydration stage for the biochemical
products
from the distillation stage 5, if the distillation stage 5 does not
sufficiently separate the
biochemicals from the fermentation water to reach the desired purity; and
[0092] Stage 9: An optional storage stage where the high-grade
biochemical
goes to storage, if the biochemical product is not immediately shipped from
the plant
(e.g., if not directly pumped into tank trucks or rail cars).
[0093] Herein the "general distillery process" refers in total to mean
the many
stages which all require energy in the form of thermal/steam or
mechanical/electrical,
wherein the thermal and mechanical energy is in part or in full supplied by a
combined heat and power plant. The portion of the energy that is not provided
from
the combined heat and power plant is derived from purchased or self-generated
power
or fuel from a supplier as will be found in a plant without mechanical vapor
compression in distillation, evaporation, dehydration, and drying and/or
without
combined heat and power, or in the case where the vapor compression in
distillation,
evaporation, dehydration, and drying and/or combined heat and power are not
being
used.
[0094] The process energy distribution in the distillery depends on
the
aforementioned stages 1 through stage 9, with the exception of the
distillation as stage
5, wherein the use of the mechanical vapor compression reduces the thermal-
steam
energy for the distillation, evaporation, and optionally dehydration.
Distillation
normally represents the largest energy-consuming stage in the distillery and
therefore
provides the largest potential opportunity for reducing the total energy of
the process.
With the exception of the mechanical and thermal energy demand of the
distillation in
stage 5, the other stages require lesser amounts of mechanical energy and/or
thermal
energy which may be met by the combined heat and power system.
[0095] Examples of the different options available to supply the
thermal-
mechanical energy produced from the combined heat and power system to the
distillery and dryer are shown in the ten schematic drawings in FIGS. 1, 2, 3,
4, 5, 6,
7, 8, 9, and 10. The thermal and mechanical-electrical distribution of the
heat and
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power is proposed in varied uses for the distillery stages. In these drawings,
like
numerals refer to like apparatus, streams, or unit operations.
[0096] The invention in some embodiments is shown in FIGS. 1, 2, 3, 4,
5, 6,
7, 8, 9, and 10, having a common process path with the process effluent flow
beginning with the raw biomass being stored in a bin 1, which delivers the
biomass
substrate via delivery duct 2 to a milling/extrusion process 3, which renders
the
substrate to a biomass flour having a suitable size so that the internal
portions of the
raw biomass are exposed for chemical conversion and processing. The biomass
flour
passes by a duct 4 with additional chemicals, which may include for example
acids or
enzymatic agents, and ultimately to the cooking process in vessel 6.
[0097] The biomass flour passing from the duct 4 is mixed with process
water
by a process line 5, where the mixed flour and process water enters the
cooking vessel
6. Within the cooking vessel 6, the application of temperature/pressure is
delivered
by a process steam line 7, and chemicals in a cooking vessel 6, proceeding
with the
chemical conversion to fermentable saccharides with the assistance of a
stirring
system 8.
[0098] The product of chemically converted slurry from the cooking
vessel 6,
passes via process line 9, to a heat exchanger 10, where the heat invested
into the
cook process is removed prior to the fermentation, since the fermentation
typically
occurs at lower temperatures than cooking. The cook slurry, after being cooled
in the
heat exchanger 10, is transported by a process line 11 which is controlled via
a valve
system 12, where the cook slurry passes to a battery of fermenters 13, which
may be
configured as a batch or continuous fermentation system, with a stirring
system 14.
[0099] The finished fermentation product, that contains the desired
biochemical product as a watery solution with other side products, passes via
a valve
controlled line 15, to process line 16, where the biochemical product of the
fermentation is heated via heat exchanger 10, that passes heat from the high-
temperature cook slurry going into the fermentation system to the fermentation
product leaving the fermentation system passing via a process line 17, to the
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distillation system 18 (FIGS. 1 through 7) or 18a (aqueous distillation
system, FIG.
8). In FIG. 8, the distillation system 18(a,b) includes an aqueous
distillation system
18a and an organic distillation system 18b.
[00100] The distillation system 18 or 18(a,b) further processes the
watery
fermented solution to further separate desired biochemical products from the
water.
The distillation system 18 or 18(a,b) yields a top product which has a
biochemical
product composition that in some embodiments approaches an azeotrope with
water,
or which may be near purity with respect to the desired biochemical. The
azeotrope
or nearly pure biochemical product passes out of the distillation system as
vapors via
a vapor line(s) 19 or 19(a,b). The distillation vapor line(s) 19 or 19(a,b)
leads to two
different process paths. The existing process path is labeled "Section I." The
retrofit
or enhancement systems are labeled "Section II" and "Section III".
[00101] In Section I, the vapors pass to a standard distillation
condenser 20,
with the condensed distillation top product passing via liquid line 21 to a
holding
reflux tank 22 (reflux tank in FIG. 1 through FIG. 7 and FIG. 9, and phase-
separation
tank in FIG. 8).
[00102] The distillation condenser system 20 is cooled by a cooling
system 23,
(cooling tower). The cooling water from the cooling system 20 passes via a
pipe 24
to a circulation pump 25, which pumps the cooling water by a valve controlled
pipe
26, to the condenser 20, after which the cooling water is returned via a pipe
27 to the
cooling system 23.
[00103] The distillation top product leaving the condenser passes via
the liquid
line 29(a,b) to the reflux tank/buffer and then to the distillation system
18(a,b) as the
reflux. At least a portion of the top product, as a single-phase azeotrope (as
in FIGS.
1 through 7 and 9), passes back to the distillation 18. In some embodiments,
at least a
portion of a phase-separable azeotrope (as in FIG. 8) passes as the total top
product,
via two separate streams based on the phase separation, passing back to the
distillation
towers; the heavy aqueous phase passes to the aqueous distillation 18a via
liquid line
29a and the light organic phase passes to the organic distillation 18b via
liquid line
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29b. The single-phase examples in FIG. 1 through FIG. 7 and FIG. 9 have the
remainder of the condensed distillation top product from the distillation
system 18
which is not passed as reflux is the final product, pure or near-pure
biochemical or an
azeotrope with water that passes via a liquid line 30 to the dehydration
system 54.
[00104] The bottom product of the distillation system, 18 or 18(a),
which
contains the heavy components as stillage, passes via a liquid line 31, to a
pump 32,
where the liquid passes via a line 33, which leads to two potential paths
wherein it is
split between the final bottom product via a liquid line 33, or cycled through
a
reboiler-condenser(s) 43(a,b) via a liquid line(s) 48(a,b), with the
difference passing
away from the distillation system, 18 or 18(a), via a liquid line 34, wherein
the
stillage is optionally further processed to recover co-products having
commercial
value. Thin stillage is returned to the reboilers 43(a) and 43(b), resulting
in thin
stillage passing to lines 48(d) and 48(e), and the reboiler condensate from
the
generated steam passing as condensate to the cook stage via line 48(c).
[00105] The distillation system, 18 or 18(a,b), may in part be driven
thermally
by a steam generator 35, wherein the production steam passes via a steam line
36,
with a control valve 37, potentially serving other thermal demands in the
system such
as steam line 7 to the cook process. The steam generator 35 is fueled via fuel
line
200. The bidirectional steam line 38 forms a connection between the steam
generator
35 and the potential waste heat from the combined heat and power system 52 via
a
steam line 53. The steam line 39 is controlled by a valve 40 to deliver steam
to
potentially drive the distillation system, 18(a).
[00106] In Section II, the top product of the distillation system, 18
or 18(a,b),
passes via a vapor line(s), 19 or 19(a,b), which is potentially split with the
condenser
system 20, passing to an optional vapor line 41(a) for single-phase
distillation or 41a
and 41b for two-phase distillation system, then passing to a compressor 42(a)
for
single-phase distillation or 42a and 42b for two-phase distillation. The
compressor(s)
42(a,b) receives mechanical energy from an engine driver 50, receiving fuel
via line
201 that produces mechanical-electrical energy to meet the demand of the
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compressor(s) and/or the electrical demand in the plant's processes, or motive
vapor
energy via steam/vapor line 87.
[00107] In FIG. 5, the compressor 42(a) compresses the
biofuel/biochemical-
rich distillate vapors that pass through vapor line 42. The compressed vapors
pass to
a reboiler-condenser 43(a), where they condense at a higher temperature than
the
stillage bottom products of the distillation 18, pumped by pump 33 via a
liquid line
48(a) to the reboiler-condenser 43(a). The stillage bottom product boils in
the
reboiler-condenser 43(a), forming steam with the steam passing via a steam
line 49, to
drive and meet the thermal demand of the distillation system 18.
[00108] In FIG. 9, the compressor 42a compresses a portion of the
biofuel/biochemical-rich distillate vapors that pass to a reboiler-condenser
43a, where
they condense at a higher temperature than the stillage bottom products of the
distillation 18 with the remaining biofuel/biochemical-rich distillate vapors
passing to
an optional compressor 42b and then passing to the dehydration vapor line 61
to
vapor-phase dehydration.
[00109] The reboiler-condenser(s) 43 or 43(a) condensate for single-
phase
distillation in FIGS. 1 through 7 and 9, and reboiler-condenser(s) 43a and 43c
condensate for phase-separated distillation in FIG. 8, as near-pure
biochemical or
azeotrope, passes via liquid line 44 to a compression-side reflux tank 45 in
FIG. 1
through FIG. 7 and FIG. 9 or phase-separation tank 45 in FIG. 8. The condensed
pure
or azeotrope biochemical product passes via liquid line 46 to the distillation
system 18
as reflux, with the remainder being final top product for single-phase
distillation in
FIG. 1 through FIG. 7 and FIG. 9 or reflux to 18b in two-phase distillation in
FIG. 8
via line 46. The condensate of the two-phase azeotropes separate with the
light liquid
via line 46 to organic distillation tower 18b, and the heavy aqueous mixture
to the
aqueous distillation tower 18a via liquid line 30.
[00110] The single-phase distillation in FIG. 1 through FIG. 7 and FIG.
9
having the compressor side reflux tank 45 passes the residual condensate as
final
distillation top product via liquid line 47, to the dehydration system 54
where FIG. 9
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may pass all final biofuel or biochemical to the dehydration as compressed
vapors via
42b to vapor line 61.
[00111] The two-phase distillation system example in FIG. 8 passes the
final
biochemical bottom product from the organic distillation tower 18b, via liquid
line 47,
passing to reboiler 43c (reboiler/organic vaporizer) and via liquid line 54,
passing to
reboiler 55. The organic vapors generated in the reboiler 43c, pass to the
organic
distillation tower 18b via the vapor line 46, and from reboiler 55, the vapors
are
passed to organic distillation tower 18b the vapor line 61. The remaining
final
biochemical product not passing to the reboilers, 42c and 55, passes via the
liquid line
73, to the biochemical storage tank 74.
[00112] The engine driving the combined heat and power system 50
generates
mechanical power for the compressor(s) and/or thermal energy for the motive
vapors
for the vapor jet via line 91, 42(a,b,c), and electrical power for the
distillery system
via electrical generator 102. The waste heat from the engine provides a source
of
thermal energy to drive the distillery, via a heat duct 51.
[00113] The vapor generator 90 produces vapors, passing via line 91,
for
driving the thermal vapor compressor 42. The waste heat from the engine
provides a
source for thermal energy to drive the thermal vapor compressor 42 via line
92, and
thermal source to drive the distillery, via line 51.
[00114] The waste heat from the combined heat and power system 50
passes
via a piping/duct system 51, to a point where the heat is used directly or it
passes to a
heat exchanger 52. The heat exchanger 52 may generate steam from a heat
recovery
steam generator (HRSG), wherein recovered heat as steam passes via steam line
51,
and wherein the produced steam goes to meet steam demands throughout the
distillery
via the steam line 53. Steam line 53 connects to steam line 39 going to the
distillation
system, 18(a).
[00115] Steam line 38 connects to steam line 7 that drives the cook
tank 6 and
connects to steam line 56 that drives the azeotrope dehydration vaporizer 55.
Thereby, the waste heat from the combined heat and power system 50 provides
the
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thermal energy required in the cook process, the distillation process, and/or
the
dehydration system.
[00116] The single-phase distillation top product, for FIG. 1 through
FIG. 7,
passes via liquid lines 30 and 47¨when an azeotrope requires further removal
of
water to reach the desired biochemical product quality¨to a pressure-swing
vapor-
phase molecular sieve dehydration or other final dehydration system. This
system
receives the azeotrope product via line 54. The liquid or vapor azeotrope
product
moving to the dehydration system from the distillation should be vaporized or
superheated vapors at an increased pressure, which occurs in the heat
exchanger 55
(steam-driven organic vaporizer). The steam via line 56 condenses as the
azeotrope
vaporizes or superheats via line 54, wherein the azeotrope vapors pass via
vapor line
61 to the dehydration system. The process steam which drives the vaporizer
heat
exchanger 55 condenses and the liquid condensate is recycled to the steam
generator
35, and/or to the waste heat¨driven steam generator (HRSG) 53 via condensate
line
57 passing to recycle pump 58. The recycle condensate passes to the steam
generator
35 via condensate line 59 and/or moves via condensate line 60 to the waste
heat¨
driven HRSG 52.
[00117] The two-phase distillation, as for FIG. 8, passes the final
organic
product from the organic distillation tower 18(b) via liquid line 47. The
final product
passes to reboiler 43c (reboiler/organic vaporizer) wherein vapors are
produced to
drive the organic distillation tower 18b via the vapor line 46c, with the
remainder of
the organic product passes to the liquid line 54. The final organic liquid
product
moving via line 54 passes to a reboiler 55 (steam-driven organic vaporizer)
which
generates vapors that pass via vapor line 46b, which passes vapors to vapor
line 46c,
which passes the vapors to the organic distillation tower 18b. The process
steam
which drives the vaporizer heat exchanger 55 condenses and the liquid
condensate is
recycled to the steam generator 35, and/or to the waste heat¨driven steam
generator
(HRSG) 53, via condensate line 57 passing to recycle pump 58. The recycle
condensate passes to the steam generator 35, via condensate line 59 and/or
moves via
condensate line 60 to the waste heat¨driven HRSG 52.
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[00118] In the FIG. 1 through FIG. 7 and FIG. 9 single-phase
distillation
systems, which produce azeotropes with excessive water, the pressurized
azeotrope
distillation top product is passed to the vapor-phase dehydration system. The
dehydration system is depicted as a three-bottle system, although the number
of
bottles may be two or greater. The described dehydration system passes the
pressurized vapors via a three-valve system wherein one of the bottles is in
dehydration mode while the two alternative bottles are being regenerated under
low
pressure. The three bottles are cycled in a round-robin style with each bottle
being
used for a period based on the capacity of the dehydration medium, while the
alternative bottles are regenerating through application of a vacuum to
recover the
captured water. A portion of the dehydrated product is used to backflush the
regenerated bottles, so the regenerated bottle can be placed back in service
when the
captured water is removed.
[00119] The dehydration system, in FIG. 1 through FIG. 7 and FIG. 9,
passes
the pressurized vapors via vapor line 61 to a system of control valves,
62a/62b/62c,
wherein an open valve passes the pressurized vapors to the appropriate vapor
line,
63a/63b/63c, which passes the product to the dehydrating bottle, 64a/64b/64c,
that is
in service during that period of operation. The dehydrated product passes
through the
dehydrating bottle via the exiting control valves, 65a/65b/65c, to vapor line
66 as the
anhydrous biochemical product.
[00120] The dehydration bottles being regenerated pass a fraction of
the
dehydrated vapors from the one active bottle to backflush the regenerating
bottles.
The low-pressure bottle is controlled by control valves, 67a/67b/67c, with the
regeneration vapors containing a mixture of the regenerated water vapors and
the
backflush anhydrous product passing via the vapor line 68. The regeneration is
driven
by a vacuum pump system 69, wherein the vapors are pumped via line 70. The
dehydration regeneration product is returned to the distillation system 18 via
line 71
for re-distillation of the regeneration product containing the backflush
product.
[00121] The final anhydrous biochemical product from the dehydration
passes
as a vapor to an anhydrous condenser reboiler 72, wherein the final product is
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condensed and passed via liquid line 73 to storage tank 74 (e.g., anhydrous
biochemical tank). The anhydrous condenser is cooled by the condenser water
via
condensate water line 75, wherein the heated water is vaporized to steam in
the
reboiler 72, with the steam passed via line steam line 75, and wherein the
steam may
be used to drive the thermal demands of the distillery.
[00122] The process steam boiler 35 has makeup water added into the
condensate return line 60 and/or 75, via the water lines 300 and/or 301.
[00123] In section III, the dryer drum 80 receives drying heat via
heated
exhaust from combustion burners or a heated drum. The water vapor-laden dryer
exhaust gases pass through line 81, connected to reboiler-evaporator 82 feed
makeup
water from line 302, that recaptures waste heat from the exhaust gases, with
partial
condensation where the condensate passes via line 83 as process water. The
makeup
water in reboiler-evaporator 82 boils, forming low-pressure steam which passes
via
line 84 to compressor 85, as depicted in FIG. 1, FIG. 2, FIG. 3, FIG. 4, FIG.
5, FIG. 6,
FIG. 7, FIG. 8, FIG. 9 and FIG. 10, or vapor jet 85 driven by motive steam
generated
from steam generator 35 via line 87, which raises the pressure and/or
temperature of
the steam passing to process steam line 76 via line 86 for use in meeting
plant process
requirements.
[00124] Purchased or self-generated electrical power 100 is used to
meet the
process electrical demand for the milling/extrusion, cook stirring,
fermentation
stirring, and pumping, 101. The combined heat and power system 50, which
consumes fuel via line 201, generates electrical power 102, which offsets
other
electrical power requirements 100. The thermal energy captured from the
combined
heat and power system 50 generates steam via the HRSG 52, which offsets the
fuel
consumed in the steam generator 35 provided fuel via line 200. The portion of
recovered waste heat from the combined heat and power via line 201 reduces the
fuel
200 required in the steam generator 35.
[00125] The combined heat and power system provides local
mechanical/electrical energy 201, and recovered waste thermal energy 52,
wherein the
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mechanical/electrical demands of the distillery can be met through the use of
local
energy production via power line 102. The mechanical energy consumed in the
mechanical vapor compression compressor 42 reduces the thermal energy demand
of
the distillery by reducing the steam demand in steam line 40 to the
distillation 18,
and/or thermal vapor compression by vapor jet 42 reduces the thermal energy
demand
of the distillery in line 40 to distillation 18. When Compound MVR-CHP Section
II
is operated, a large portion of the steam formerly or otherwise produced by
consuming the fuel 200, in the steam generator 35, is provided by steam
generated
from heat recaptured in reboiler(s) 43(a,b) that would otherwise be lost to
cooling
tower 23 in Standard Distillery Section I standard operations. Operating
Section II
provides a net reduction in both fuel required 200 and electrical power 100.
Fuel
consumed in the engine/CHP drives the compressor(s) 42(a,b), and generates
excess
electrical power 102 to meet plant needs, offsetting electrical power 100
previously or
otherwise purchased to meet plant demand¨yielding a reduction in energy demand
for both fuel and electrical power.
[00126] The
example of FIG. 1 preferably sizes the combined heat and power
system to produce mechanical and electrical energy to drive the mechanical
vapor
compression in stage 5, referring to the above-describes stages 1 through 9.
The
thermal energy of the distillation is greatly reduced, and the electrical
energy beyond
the amount required to drive the compressor of the vapor compression system,
is used
to generate electrical power. This electrical power serves the electrical
demand of the
other stages which require mechanical energy such as pumping, stirring as in
the
cooking in stage 2, and fermentation in stage 4. FIG. 1 shows heat from the
combined
heat and power system used to generate steam by heat recovery with steam
generation, in which the steam is passed on to potentially all other thermally
intensive
stages such as the cook in stage 2, the distillation in stage 5 and in stage 7
for co-
product drying (for any steam not offset by the mechanical vapor compression),
and/or the dehydration in stage 8. Through this approach, the combined heat
and
power may be sized to provide mechanical energy as needed in the vapor
compression
with the residual power offsetting the otherwise more expensive electrical
costs of the
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distillery stages. The resulting waste heat meets, but does not exceed, the
other
thermal-steam demands of heat-intensive stages.
[00127] The example of FIG. 2, like FIG. 1, shows the distribution of
heat from
the optional combined heat and power system used to produce mechanical and
electrical energy to drive the mechanical vapor compression in stage 5,
wherein the
thermal energy of the distillation is greatly reduced, and the electrical
energy beyond
the demand to drive the compressor of the vapor compression is used to
generate
electrical power which goes to serve the electrical demand of the other stages
which
require mechanical energy such as pumping, stirring (as in the cooking in
stage 2) and
fermentation in stage 4. FIG. 2 shows a split of the heat from the combined
heat and
power system used to generate steam by heat recovery with steam generation,
wherein
the steam is passed on to potentially all other thermally intensive stages,
such as the
cook in stage 2, the distillation in stage 5 (for any steam not offset by the
mechanical
vapor compression), and/or the dehydration in stage 8. Part of the waste heat
of the
combined heat and power system may be passed on to directly dry co-products of
the
distillery stillage in stage 7, and generate steam from the recovered heat
from exhaust
gases through vapor compression.
[00128] The example of FIG. 3 like FIG. 1 and FIG. 2 shows the
distribution of
the heat from the optional combined heat and power system used to produce
mechanical and electrical energy to drive the mechanical vapor compression in
stage
5, wherein the thermal energy of the distillation is greatly reduced, and the
electrical
energy beyond the amount needed to drive the compressor of the vapor
compression
serves the electrical demand of the other stages which require mechanical
energy such
as pumping, stirring as in the cooking in stage 2, and fermentation in stage
4. FIG. 3
shows the heat from the combined heat and power system used to directly
preheat
process water by using the heated cooling water from the power system, or by
preheating the process water with a combination of direct and out-of-contact
heat
exchange, wherein the cook in stage 2 has reduced thermal demand and/or using
the
power system waste heat to directly dry co-products of the distillery stillage
in stage
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7, and generate steam from the recovered heat from exhaust gases through vapor
compression.
[00129] The example of FIG. 4 like FIG. 1 and FIG. 2 shows the
distribution of
the heat from the optional combined heat and power system used to produce
mechanical and electrical energy to drive the mechanical vapor compression in
stage
5, wherein the thermal energy of the distillation is greatly reduced and the
electrical
energy may be less than or equal to the amount needed to drive the compressor
of the
vapor compression system, leaving little or no residual electrical to serve
the electrical
demand of the other stages which require mechanical energy such as pumping,
stirring as in the cooking in stage 2, and fermentation in stage 4. FIG. 4
shows the
heat from the combined heat and power system used to generate steam by heat
recovery with steam generation, wherein the steam is then passed through a
steam
turbine which generates electricity with the low pressure stage of the turbine
passing
the exhaust steam on to potentially all other thermally intensive stages, such
as the
cook in stage 2, the distillation in stage 5 (for any steam not offset by the
mechanical
vapor compression), and the dehydration in stage 8, and the steam turbine
electrical
power is used to meet the electrical power demand of the other stages which
require
mechanical energy such as pumping, stirring as in the cooking in stage 2, and
fermentation in stage 4.
[00130] The examples of FIG. 5 and FIG. 6, like FIGS. 1, 2, 3, and 4,
show the
distribution of the heat from the optional combined heat and power system used
to
produce mechanical and electrical energy to drive the mechanical vapor
compression
in stage 5 and stage 7, wherein the thermal energy of distillation and
evaporation are
greatly reduced and the electrical energy generated may be less than or equal
to the
amount needed to drive the compressor of the vapor compression system, leaving
little or no residual electrical to serve the electrical demand of the other
stages which
require mechanical energy such as pumping, stirring as in the cooking in stage
2, and
fermentation in stage 4. FIG. 5 shows the distillation in stage 5 by
compression
passes the latent heat on to a multi-effect evaporation in stage 7 for the
concentration
of the thin stillage bottoms from stage 5, and the cascaded steam from the
final
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evaporation effect is part of the mechanical vapor compression that recycles
the steam
back to distillation stage 5. The waste heat from the combined heat and power
is
distributed to meet the thermal demands of a cook process stage 2,
distillation stage 5,
drying stage 7 by generated steam from the recovered heat of exhaust gases
through
vapor compression, and dehydration stage 8.
[00131] The example of FIG. 7, like FIGS. 1, 2, 3 and 4, shows the
distribution
of the heat from the optional combined heat and power system used to produce
mechanical and electrical energy to drive the mechanical vapor compression in
stage
and stage 7, wherein the thermal energy of distillation and evaporation is
greatly
reduced and the electrical energy generated may be less than or equal to the
amount
needed to drive the compressor of the vapor compression system, leaving little
or no
residual electrical energy to serve the electrical demand of the other stages
which
require mechanical energy such as pumping, stirring as in the cooking in stage
2, and
fermentation in stage 4. FIG. 7 shows the distillation in stage 5 by
compression
passes the latent heat on to a multi-effect evaporation in stage 7 for the
concentration
of the thin stillage bottoms from stage 5, and the cascaded steam from
reboiler-
evaporator together with the final evaporation effect is part of the
mechanical vapor
compression that recycles the steam back to drive the distillation stage 5.
The waste
heat from the optional combined heat and power is distributed to meet the
thermal
demands of a cook process stage 2, distillation stage 5, drying stage 7 with
generated
steam from the recovered heat from exhaust gases through vapor compression,
and
dehydration stage 8.
[00132] The example of FIG. 8, like FIGS. 1, 2, 3, and 4 shows the
distribution
of the heat from the optional combined heat and power system used to produce
mechanical and electrical energy to drive the mechanical vapor compression in
stage
5 and stage 7, wherein the thermal energy of distillation and evaporation is
greatly
reduced and the electrical energy generated may be less than or equal to the
amount
needed to drive the compressor of the vapor compression system, leaving little
or no
residual electrical energy to serve the electrical demand of the other stages
which
require mechanical energy such as pumping, stirring as in the cooking in stage
2, and
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fermentation in stage 4. FIG. 8 shows the distillation in stage 5 by
compression
passes the latent heat on to a multi-effect evaporation in stage 7 which is
comprised of
two separate reboilers, with the concentration of the thin stillage bottoms
from the
aqueous distillation tower of stage 5, and the cascaded steam from reboiler-
evaporator
together with the final evaporation effect is part of the mechanical vapor
compression
that recycles the steam back to drive the aqueous distillation tower of stage
5 and
biochemical bottom product cascaded vapors from the organic reboiler to the
organic
distillation tower. The waste heat from the combined heat and power is
distributed to
meet the thermal demands of a cook process stage 2, and distillation stage 5.
[00133] The example of FIG. 9, like FIGS. 1, 2, 3, and 4 shows the
distribution
of the heat from the optional combined heat and power system used to produce
mechanical and electrical energy to drive the mechanical vapor compression in
stage
5, stage 7 and stage 8, wherein the thermal energy of distillation,
evaporation, and
dehydration is greatly reduced and the electrical energy generated may be less
than or
equal to the amount needed to drive the compressor of the vapor compression
system,
leaving little or no residual electrical energy to serve the electrical demand
of the
other stages which require mechanical energy such as pumping, stirring as in
the
cooking in stage 2, and fermentation in stage 4. The waste heat from the
combined
heat and power is distributed to meet the thermal demands of a cook process
stage 2,
distillation stage 5, and dehydration stage 8.
[00134] The example of FIG. 10, like FIG. 1, 2, 3, 4, 5, 6, 7, 8, and
9, shows
the capture of low-grade dryer exhaust heat from the stage 7 stillage handling
and
processing by passing it into a reboiler-evaporator where process water is
boiled at
low temperature. This low-pressure steam is raised in pressure and/or
temperature,
via mechanical vapor compression and/or thermal vapor compression, with the
compressed steam being passed into the distillery as process steam. The dryer
exhaust heat capture and conversion to compressed steam may be applied to any
of
the configurations of distillery or bio-refineries processes such as those
shown in FIG.
1, 2, 3, 4, 5, 6, 7, 8, 9 and 10.
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[00135] In should be noted that regarding FIGS. 1 to 10, specific unit
operations may be omitted in some embodiments, and in these or other
embodiments,
other unit operations not explicitly shown may be included. Additionally,
multiple
pieces of equipment, either in series or in parallel, may be utilized for any
unit
operations, pumps, etc. Also, solid, liquid, and gas streams produced or
existing
within the process may be independently recycled, passed to subsequent steps,
or
removed/purged from the process at any point.
[00136] As will be appreciated by a person of ordinary skill in the
art, the
principles of this disclosure may be applied to many biorefinery
configurations
beyond those explicitly disclosed or described in the drawings hereto. Various
combinations are possible, and selected embodiments from some variations may
be
utilized or adapted to arrive at additional variations that do not necessarily
include all
features disclosed herein. In particular, while some embodiments are directed
to
ethanol as the primary biofuel/biochemical, the present invention is by no
means
limited to ethanol.
[00137] For example, the invention may be applied to ABE fermentation,
producing a mixture of acetone, n-butanol, and ethanol. One or more additional
distillation or other separation units may be included, to separate components
of a
fermentation mixture. Also, in some embodiments, the primary product is less
volatile than water (at atmospheric pressure), rather than more volatile, as
is the case
with ethanol. An example of a biofuel/biochemical less volatile than water is
isobutanol.
[00138] The present invention also provides a biofuel or biochemical
product
produced by a process comprising a method of modifying a distillery or
biorefinery,
wherein the distillery or biorefinery converts biomass into the biofuel or
biochemical,
and wherein the biofuel or biochemical is purified by distillation, the method
comprising:
(i) introducing a vapor compression unit comprising a mechanical vapor
recompression (MVR) unit and/or thermal vapor recompression (TVR) unit to
recover
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latent heat, evaporation, drying, and/or dehydration processes, and provide a
reduction
in process thermal energy usage in the distillery or biorefinery; and
(ii) optionally introducing a combined heat and power (CHP) system having a
CHP engine, to provide mechanical, electrical, and/or thermal energy for
driving the
vapor compression unit, wherein residual waste heat of the CHP engine offsets
the
process thermal energy usage in the distillery or biorefinery, in conjunction
with the
vapor compression unit; and wherein integration of the vapor compression unit
with
the optional CHP system is preferably balanced to optimize process energy
requirements, process carbon intensity, and/or process energy costs.
[00139] These and other combinations of heat and power optimization are
available by the mixed combination of mechanical vapor compression integrated
together with combined heat and power. The integration of these two
complementary
technologies, wherein the vapor compression in distillation, evaporation,
drying, and
optionally dehydration reduces the total thermal energy demand of the
distillery, and a
portion of the saved thermal energy fuel is then dedicated to combined heat
and power
to offset process electrical energy, allows for a simultaneous reduction in
the thermal
energy demand and electrical energy demand, together with a reduction in
process
energy costs and reduced carbon intensity for the plant.
[00140] Some variations of the invention provide a method for
optimizing
energy usage, production economics, and environmental performance in modifying
existing distillation systems. The operational capabilities of a distillation
system are
maintained while a more energy-efficient process is added that diverts some
portion
of the distilled vapors, which would otherwise be condensed, and compresses
them,
heating them and raising their boiling point. The compressed vapors are
condensed in
a reboiler, capturing the energy released that would otherwise be lost to
cooling water
flowing through a condenser. The method used to drive the compressor, the
design of
the reboiler, and generation of additional usable energy are balanced to
provide fully
redundant capabilities with respect to the existing system and the desired
optimization.
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[00141] In one aspect, a method is provided for the modification and
augmentation of a distillery wherein the addition of the disclosed
distillation methods
for heat management by mechanical vapor compression which recovers the latent
heat, provides a reduction in process thermal energy together with combined
heat and
power for the addition of mechanical and electrical energy for driving the
compression, wherein the residual waste heat of the engine offsets thermal
energy
required in the distillery in conjunction with the vapor compression in
distillation,
evaporation, drying, and/or dehydration. The integration of the vapor
compression
with combined heat and power is balanced to optimize the reduction in process
energy
requirements, process carbon intensity and/or process energy costs.
[00142] In some embodiments, the vapor compression is sized or operated
to
reduce the thermal energy required in distillation, evaporation, drying,
and/or
dehydration in concert with the standard steam generator that is operated at a
reduced
rate as a result of the reduction in steam energy demand due to energy
recovered by
the mechanical vapor compression in distillation, evaporation, drying, and/or
dehydration. In these or other embodiments, the optional combined heat and
power
system is sized or operated in concert with the mechanical or thermal demand
of the
vapor compression and the thermal energy demand of the distillery wherein part
of,
some of, or all of the thermal energy is provided by the waste heat recovered
by the
combined heat and power system.
[00143] The combination of mechanical vapor compression in
distillation,
evaporation, drying, and/or dehydration and combined heat and power allows
balancing of use in the distillery based on the market price of process fuel
energy and
electrical energy unit price, wherein the total process energy is not
minimized, though
the process energy costs are minimized based on the relative pricing of the
two energy
sources.
[00144] Also, the combination of vapor compression in distillation,
evaporation, drying, and/or dehydration and combined heat and power allows
minimization of the carbon intensity of the process through selective usage of
electricity and thermal fuel in a manner that minimizes the total carbon
intensity of
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the process energy, though the process energy costs are not minimized because
of the
relative pricing of the two energy sources and the individual carbon
intensities
allocated to the thermal and electrical process energy lifecycles.
[00145] By recapturing and recycling process heat, the disclosed
technology
provides an option for expanding biofuels/biochemical production that:
(a) reduces or eliminates the need for additional steam-generating capacity;
(b) reduces or eliminates the need for additional cooling capacity; and
(c) reduces or eliminates seasonal production restrictions due to cooling
system capacity limitations during high ambient temperatures and humidity.
In addition, the disclosed technology can permit production increases without
exceeding allowable air emissions and water usage and discharge restrictions
under
existing environmental permits.
[00146] Some embodiments of the invention provide a system or sub-
system
comprising or consisting of the process or apparatus configuration depicted in
any one
of FIGS. 1 to 10, or portions thereof, or any other disclosure set forth
herein. Some
embodiments of the invention provide instructions to retrofit an existing
distillery or
biorefinery with the process or apparatus configuration depicted in any one of
FIGS. 1
to 10, or portions thereof, or any other disclosure set forth herein.
[00147] The throughput, or process capacity, may vary widely from small
laboratory-scale units to full commercial-scale biorefineries, including any
pilot,
demonstration, or semi-commercial scale. In various embodiments, the process
capacity is at least about 1 kg/day, 10 kg/day, 100 kg/day, 1 ton/day (all
tons are
metric tons), 10 tons/day, 100 tons/day, 500 tons/day, 1000 tons/day, 2000
tons/day,
3000 tons/day, 4000 tons/day, or higher.
[00148] All publications, patents, and patent applications cited in
this
specification are incorporated herein by reference in their entirety as if
each
publication, patent, or patent application was specifically and individually
put forth
herein.
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[00149] In this detailed description, reference has been made to
multiple
embodiments of the invention and non-limiting examples and drawings relating
to
how the invention can be understood and practiced. Other embodiments that do
not
provide all of the features and advantages set forth herein may be utilized,
without
departing from the spirit and scope of the present invention. This invention
incorporates routine experimentation and optimization of the methods and
systems
described herein. Such modifications and variations are considered to be
within the
scope of the invention defined by the claims.
[00150] Where methods and steps described above indicate certain events
occurring in certain order, those of ordinary skill in the art will recognize
that the
ordering of certain steps may be modified and that such modifications are in
accordance with the variations of the invention. Additionally, certain of the
steps may
be performed concurrently in a parallel process when possible, as well as
performed
sequentially.
[00151] Therefore, to the extent that there are variations of the
invention, which
are within the spirit of the disclosure or equivalent to the inventions found
in the
appended claims, it is the intent that this patent will cover those variations
as well.
The present invention shall only be limited by what is claimed.
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