Note: Descriptions are shown in the official language in which they were submitted.
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18329 WO 91/112~0 PCT/~P9~/0~095
2 ~ 9 6
TRANSL~TION
"Process and A~aratus for Recovery of HYdrocarbons~from a Gas-Air
Mixture" ~
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The invention relates to a process for an apparatus for recovery of
hydrocarbons from a gas-air mixture resulting from the decanting-or
charging of carburetor or diesel fuels according to the preamble of .-
patent claim 1 or of patent claim 6.
From DE 36 09 292 C2 such a process is known in which the gas to be
cleaned is cleaned in two successive cleaning stages. After the
~irst cleaning stage, which is formed as a refrigeration unit, the .-
remaining impurities in the gas to be cleaned are burned in the
second cleaning stage. ~he energy thus liberated is used to drive ~ ;
the first cleaning stage. The first cleaning stage is so driven
that the amount o~ the impurities remaining thereafter in the gas is
~u~P~ nt to drive the first cleaning stage with the aid o~ ~he
energy liberated in the second cleaning stage.
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18329 W0 91/11240 2 ~ $ ~ PCT/EP9lfO0095
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With the known method or the known apparatus, the first cleaning :
stage which is formed as a refrigeration device is never utilized at ::
approximately its maximum capacity since the gas stream leaving it
must always entrain sufficient combustible hydrocarbons and impuri- .
ties to allow the second stage equipped with a combustion unit to
have sufficient capacity for driving the refrigeration unit.
Furthermore, in the case of the known process or the known apparatus :.
at start-up, there are problems in that the combustion apparatus .
initially must be charged with a completely uncleaned waste gas
before the refrigeration unit can basically be brought into
operation. This can be effected in such manner that contaminants
during start-up o~ the entire apparatus, which normally would be
condensed out in the refriyeration unit and which are combustible,
can be released substantially completely into the atmosphere with
the gas stream leaving the Gombustion unit. Besides, it is ad- :
vantageous to provide a separate fuel supply for the combustion
apparatus by means of which the combustion apparatus can be brought
into operatlon before the start-up o~ the entire apparatus itself.
The in~ention presents the ob~ect of providing a process or an
apparatus for the recovery of fuel from a gas or mixture in which .:
the cooling and condensation required for the cleaning is effected
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18329 ~0 ~1/11240 2~ PcT/~Pgl/0oo95
to the greatest possible degree and whereafter the hydrocarbons
which remain after cooling and condensation in the gas-air mixture ~ -
are usable.
This object is achie~ed according to the invention by the features
of the characterizing part of the parent claim 1 or the patent claim
6. According to the invention, the complete capacity of the
refrigeration apparatus is used for the condensation and cooling of
the gas-air mixture and thus for the separation of hydrocarbons and
impurities. Notwithstanding such fuel utilization, an optimum
operation of the fueled engine is ensured since this is supplied
with the fuel quantity required for its operation. Both the refrig-
eration unit and the fueled engine can be optimally utilized to
their capacities.
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According to the el~odiment of patent c].aim 2 or patent claim 7, the
energy generated in the combustion fuel engine is utilizable in an
especially simple way to drive refrigeratlon apparatus.
By maintaining the fuel quantity injected in accordance with patent
claim 3 or patent claim 8, no external energy 8upply is required for
operation of the cooling apparatus.
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18329 W0 91/11240 2~ g PCT~P91j~0095
By means of the specific gravity separation given in patent claims 4
or 9, the condensate deriving from the refrigeration unit is
separatable without high cost into its components, for example water
and liquid fuel.
In accordance with the process of patent claim S, in which the com-
bustible fuel engine is continuou51y operated to generate electrical
energy, the cooling or condensation stage is si~ultaneously included
as part of the supply unit for the combustible-fuel engine.
Fluctuations of the fuel quantity resulting from cooling and
condensation are compensated by storage of the fuel and matching
metering of further fuel. An advantageous power capacity for a
combustion engine operated in such manner can amount to about lO0
kW. With such continuous operation of the combustion engine, the
highly volatile hydrocarbons resulting from the cooling and
condensation can be utilized logically for energy generation before
they are transformed in a gaseous state and can pass into the
atmosphere.
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18329 ~O 91/11240 2 0 '~ ~ ~ 9 6 PCT/EP91/00095
In the embodiment of the refrigeration unit according to patent
claim 10, the refrigerant actually used in the evaporator stage of
the evaporator passes from a liquid into the vapor state and removes
from the contaminated gas or mixture the medium to be cooled -
utilizing the heat of evaporation required for the change of state
of the refrigerant. This evaporator stage is followed by an after-
-evaporator stage; in the latter the refrigerant actually used, now
in vapor form, is brought from its evaporation temperature which is
lower, by comparison to that of the refrigerant for which the
expansion or depressurization control valve is designed by heating
to a temperature corresponding to that of the tlatter3 re~rigerant
at the expansion valve after e~aporation and the usual superheating.
~his allows complete utilization of the enthalpy of the refrigerant
without necessitating the provision of a portion of the evaporator
state ag a superheating stretch re~ulting in a loss of power.
The after-evaporation stage, in which the vapor state refrigerant
actually used is heated to the temperature o~ the refriyerant for
which the expansion or depressurization valve is designed after the
required superheating of the latter refrigerant for this expansion
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18329 wo 91/11240 2 ~ 9 ~ PCT/EP91/00095
control valve, is utilizable as a cooling stage because of the
comparatively high temperature diEference between this latter
temperature and the evaporation temperature of the refrigerant
actually used for the capacity thereof.
By ~orresponding constructural configuration and assembly of the
evaporator stage and the after-evaporator stage, the medium to be ~ -
cooled initially is passed through the after-cooling stage and then
passed through the evaporator stage itself. The after-cooling stage
is thus effectively used as a precooler. The control of the
expansion-control valve is so effected that the refrigerant at the
outlet of the evaporator assumes a pressure and temperature for
which the expansion-control valve is set for control of the provided
parameters. The provision of the evaporator stage according to
patent claim 11 allows an especially exact control of the refrig-
erant volumetric flow from the superpressure reservoir into the
evaporator.
According to patent claim 12, the after-evaporator stage capacity is
dimensioned to be sufficient so that even with the precooling, the ~ -
temperature of the medium to be cooled is dropped significantly.
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18329 ~0 91/11240 PC~P91~00095
An especially advantageous operation of the refrigerating unit is
effected by the provision according to claim 13 of the expansion-
-control valve and evaporator in combination with the refrigerant
there givPn.
The invention is described in greater detail below with respect to
an embodiment thereof with referance to the drawings. They show:
Figure 1 a schematic illustration of an embodiment of the process
of the invention or the apparatus of the invention;
Figure 2 an embodiment oP the cascade cooling unit of Figure 1 and
Figure 3 an embodimen of the evaporator shown in Figure ~.
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An air-gas mixture A, which from decanting or filling contains
carburetor or diesel fuel, is fed to a refrigerating unit 15. The
refrigerating unit 15 is formed from a liquid cooler 17 and a
cascade cooling device 18 traversed in succession by the air-~as
mixture A. In the refrigerating unit 15, the air-ga~ mixture is
cooled and condensed. The condensate which separates out, which is
in the liquid form and contains impurities, water and hydrocarbons,
is supplied to a specific-gravity separator 22 in which the
different components are separated.
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18329 WO 91/11240 PCT~EP91/00095
The air-gas mixture B from the refrigerating unit 15, which contains
small quantities, still of some impurities of hydrocarbons, is
supplied to a combustion-power ~internal combustion] engine lG in
which the remaining combustible components are burned.
Between the refrigerating unit 15 and the internal combustion engine
16, a metering device 19 is arranged which injects additional fuel
into the air-gas mixtur~ B deriving from the refrigerating unit 15.
This additional fuel quantity can be so dimensioned that the energy
recovered from the internal combustion ensine 16 is sufficient to ~ ;
drive the refrigerating unit 15.
During the start-up of the entire system, the internal combustion
engine 16 can be initially driven exclu!3ively by the fuel quantity
injected. In the metering device 19, the injected quantity of fuel
can be matchad to the fuel content in the air-gas mixture B.
From internal combustion engine 16, an exhau6t gas stream C emerges
which sati~fles appliaable legal requirements or i~ slgniflcantly
therebelow. -
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18329 ~0 91~112~0 2~ ~99 9 6 PCT/EP91jO0095
The mechanical energy recovered by the internal combustion engine 16
is applied t~ a generator 10 in which it is transformed into
electrical energy. This electrical energy is used for supply of the
refrigerating unit 15. It is, however, also possible to feed this
energy into the network 21.
In the cascade cooling unit 18, shown in Figure 2, the refrigerant
utilized is conducted from a superpressure reservoir 1 via an :~:
expansion or depressurization control valve 2 into an evaporator 3.
The evaporator 3 has an evaporator stage 4 in which the refrigerant
passes form the liquid state into the vapor state. Durlng thls
transformation process, the medium to be cooled flowing past the
evaporator stage 4, namely in the impure gas-air mixture, has the
requisite heat quantity abstracted for evaporation of the refrig-
erant. Downstream of the evaporator stage 4 is an after~evaporator
stage 5 in which the vapor-form refrige;rant is heated to a tempera-
ture detected by a measuring device 6 designed to control the
expansion-control valve 2.
This ~fter-evaporation stage is, by corresponding structuring and
arrangement of the individual parts of the evaporator with respect
to the volumetric flow o~ the medium to be cooled, here the gas-air
mixture to be cleaned, usable as a precooler.
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18329 WO 91/11240 2 ~ ~ ~ 9 ~ ~ PCT/EP91jO0095
Downstream of the evaporator 3, the refrigerant in a conventional
manner is conducted through a compressor 9 provided with an inlet .
valve 7 and an outlet valve 8, and a condenser or heat exchanger 10
back to the superpressure reservoir 1.
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The refrigerant utilized for the cooliny process has at a pressure
of 1 bar, an evaporation temperature of minus 88 degrees C and is
injected via a depressurization-control valve or expansion valve 2 ~ :
having at a pressure of 1 bar, an evaporation temperature of minus
45 degrees C. As a result, the following is the effect:
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The expansion valve 2 opens at a pressure in the evaporator 3 of 3.2 :.
bar. For the refrigerant which at a pressure of 1 bar would have an ~ :
evaporation temperature of minus 45 degrees C, this would give an .:
evaporation temperature of minus 17 deg:rees C. With the refrigerant
actually used, however, which has an evaporation temperature at 1
bar of minus 88 degrees C, at this pres!sure o~ 3.2 bar, the evapora- :
tion temperature is minus 65 degrees C. With a properly constructed
and set evaporator 3, the expansiGn valve 2 receive~ from the
pressure equalization line 11 and the ~easurin~ device 6 forming the ..
thermosensor, which is disposed downstream of the after-evaporator
stage 5, the following signals: : :
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1832~ ~0 91/112~0 PCT/~P91jO0095
2 ~ 6
Temperature minus 7 degrees C;
Pressure 3.2 bar.
For the expansion valve 2, with respect to refri~erant ~or which it
is normally designed and which at a pressure of 3.2 bar would have
an evaporation temperature of minus 17 degrees C, this would mean a
superheating of 10 K. The depressurization control or expansion - -
valve 2 is thus in the correct operating range. However, operating
with the refrigerant utilized in the present case, there is an
advantage that it manifests a temperature of minus 65 degrees C at
the evaporator stage 4 of the evaporator 3 and a total temperature
difference betwePn this temperature and the minus 7 degrees C in the
after-evaporator stage u~ed for precool.Lng.
In Figure 3, an embodiment of the evaporator 3 is illustrated in
which the evaporator stage 4 and the after-evaporator stage 5 are
very compact and with respect to the cooling medium flow D is so
arranged that the latter initially traverses the after-evaporator
stage 5 serving as precooler. To this is conneated a fir6t sec$ion
of the evaporator stage 4 directly traversed by the medium flow
following the after-evaporator stage 5, before it is reversed and
flows over a second section of the evaporator stage 4 after which it
leaves the evaporator 3 a~ the ~ubstantially clean gas-~ir ~ixture
E.
