Note: Descriptions are shown in the official language in which they were submitted.
1100(~68
` Background of the Invention
1. Field of the Invention
This invention relates to the field of coal
conversion to form hydrocarbon gases and liquids suitable for
conversion to fuels.
More particularly, this invention relates to reacting
carbonaceous material such as pulverized coal with heated
hydrogen to form hydrocarbon gases and liquids suitable for
conversion to fuels or for use as a chemical feedstock.
DescriPtion of the Prior Art
The problem is to react coal directly with hydrogen
in such a way as to maximize the yield of liquid products. A
number of researchers have shown that at the beginning of coal
pyrolysis a transient period exists for a few tenths of a second
where the coal is highly reactive toward hydrogen. If excess
hydrogen is not available during this period, some of the free-
radical pyrolytic fragments will strip molecular hydrogen from
the aromatic groups while other fragments will polymerize to
form unreactive char. The overall effect is a limited yield of
liquid and gaseous hydrocarbons, and a large yield of char. If
instead, excess hydrogen is present during the critical transient
period, many more hydrogenated fragments that are amenable to
still further hydrogenation are produced. The ove~all effect of
pyrolysis in hydrogen is a much larger yield of li~uids and
gases, and a lower char yield.
It is generally well known the conversion of coal to
liquid or gaseous fuels is achieved by the addition of hydrogen.
This may be accomplished by the direct contact of coal with
hydrogen as in the ~ureau of Mines Hydrane proces.s to produce
methane; by a cata~yzed liquid-phase reaction with hydrogen to
- 2 ~
1~0~
produce liquid products as in the Synthoil process; or in-
directly by reacting coal with steam. Many different processes
have been proposed and are under development. These schemes
vary in the method of contacting coal and hydrogen or steam,
and in the type of coal feed utilized. A solid such as coal
can be contacted with a gas in three basically different ways.
In the first, gas is forced through a fixed or slowly moving
bed of solid.
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11~68 76R18
Another method of contact is by use of a fluidized bed. With sufficiently
small solid particles and a sufficiently high gas velocity in vertical upward
flow the air dynamic drag forces on the individual particles begin to approach
the gravitational forces and the par~icles themselves begin to move about.
The bulk properties of the gas solid mixture then become those of a fluid.
Because of the improved heat and mass transfer characteristics in a fluidi2ed
bed as opposed to a fixed bed, most coal gasification processes now are the
fluidized bed variety. Yet another basic category of gas solid contacting is
entrained f1OW as in the Bigas process. In this regime gas velocities are
high enough and particle sizes low enough that the solid particles are carried
along with the gas stream. An advantage of the entrained flow processes is
the ability to utilize any grade or class of coal. Caking coals will agglo-
merate causing difficult problems when fed to fluidized or fixed bed systems.
Further advantages of entrained flow with respect togas production include
operation at high temperatures so that tar production is kept to a minimum,
adaptability to slagging conditions and high energy production per unit
volume. The present invention utilizes this type of entrained flow coal con-
version process. Heretofore no large scale attempt to use this approach for
direct hydrogenation of coal has been made.
A patent issued to W. C Schroeder, No. 3,030,297, describes a process
which comprises heating dry particles of coal entrained in a heated stream of
hydrogen at total pressure of about 500-6000 psig from a temperature below
about 300C to a reaction temperature in the range of from about 600C to
about 1000C. Two minutes are required to heat the coal particles to about
600C and then two to twenty seconds time at temperature for hydrogenation.
The slow heat-up results from the main hydrogen stream being utilized to
carry the coal into the reactor. The products of reaction are then cooled
below reaction temperature to provide a product comprised of light oil, pre-
dominantly aromatic in nature, and hydrocarbon gases, primarily methaneh,
ethane, and carbon monoxide.
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76R18
This process i5 disadvantaged in that the coal particles entrained in
the hydrogen are preheated prior to introduction into a heating chamber thus
the reaction process is started upstream of the reaction chamber which will
cause agglomeration and plugging within the conduit carrying the entrained
coal. The present invention overcomes this agglomeration problem by pro-
viding two sources of gas, one source of gas such as hydrogen brings entrained
coal into an injector at ambient temperature, and a separate source provides
heated hydrogen to an injector which contacts the entrained dense phase coal
downstream of an injector within a reaction zone thereby starting the hydro-
genation process within the reaction chamber and not upstream of the chamber.
Schroeder is further disadvantaged in that he attempts to heat the en-
trained coal particles through a tube wall. At the mass throughputs specified
in the example, it is doubtful that enough heat could be transferred through
the tube wall in a reasonable length to sufficiently heat the coal and, at
the same time, use the tube wall to contain the system pressure. This type
of reactor does not scale to the necessary larger diameters for commercial
coal conversion reasonably because the heat transfer surface-to-volume ratio
decreases rapidly with an lncrease in size~
Schroeder is still further disadvantaged in that the mixing and the
heating takes place in minutes and seconds whereas the present invention ac-
complishes the hydrogenation of the entrained coal in milliseconds and if a
uniform flow pattern can be maintained (to avoid back mixing which will cause
longer residence time and gas production instead of liquids) and if the coal
can be dispersed uniformly even on a microscopic scale (to minimize gas dif-
fusion limitations), and if rapid and efficient quenching can be achieved
(Schroeder carries the hydrogenated products through a conduit towards a
separate quenching chamber whereas the present invention ~uenches the re-
AC ~
~ products immediately upon exiting the end of the reaction chamber),
llOQ~8
76R18
then it should be possible to hydrogenate d substantial fraction of the coal
to liquid products. The utilization of rocket engine type injector principles
in a coal liquefaction plant as described in the present invention is believed
to be unique and is one of the principal objects of the invention.
Another patent issued to Schroeder et al, 3,152,063, teaches a process
which comprises dispersing pulverized and catalyzed coal, in the absence of
a pasting oil, in hydrogen under a pressure of about 500 to 4000 psig, react-
ing the mixture of coal and hydrogen at a temperature in the range of about
450 to 600C, for a gas residence time of less than about 200 seconds, cool-
ing the reaction products and recovering liquid and gas hydrocarbon products
therefrom.
Schroeder teaches passing of catalyzed coal and hydrogen into a two-
stage reactor that consists of a multiplicity of parallel tubes axially
extending within the reactor. The tubes are heated by a source of hot gas
to start the reaction within the tubes. Vaporized oil and gas products are
drawn off as wel1 as unused hydrogen to a cooling device. The residual
heavier oil and tar products are collected in the bottom of the reactor and a
source of hydrogen may then be brought in to further hydrogenate these
heavier products.
This invention is disadvantaged in that the pulverized coal must be
passed through a catalyzing process, sent through a dryer and grinder and
finally separated into minute particles by passing the coal through a screen-
ing process. The present invention utilizes finely-divided pulverized coal
directly without the foregoing pre-treatment process.
Schroeder's invention is further disadvantaged in that it also utilizes
the carrier hydrogen in the coal passages as the main source of hydrogen.
The heat-up process then takes considerable time as compared to the present
invention in that the carrier gas cannot be pre-heated prior to entering into
a reaction charnber.
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76R18
Additionally, the invention is disadvantaged in that the coal particles
are heated through a tube or a series of tubes thereby seriously affecting
the ability to scale-up the process to commercial production proportions. A
comrnercial unit would necessarily have to process in the neighborhood of 1000
tons/hour. The Schroeder patents teach a mass throuyhput Ot approximately
145 lbs/hr ft.2, a very low process rate. For example, in a commercial re-
actor using the Schroeder process, each reactor being 15 feet in diameter, 82
reactors would be needed to process 1000 tons/hr of coal. In addition, be-
cause of the small surface-to-volume ratio the reactors would have to be on
the order of one hundred feet long to transfer sufficient heat through the
wall transporting the entrained coal particles. One of the most important
advantages of the high throughput of dense phase coal particles through the
reactor of the present invention (33,000 lbs/hr ft.2) is that it is scaleable
to a commercial size. Two reactors utilizing the principles set forth in the
following specificaticns, 6-feet in diameter would process 1000 tons/hr of
coal. The heat is supp1ied directly in the hydrogen so that vessel surface-
to-volume ratio is not a limiting factor.
Although the chemistry of coal pyrolysis and hydrogenation has been ap-
parent for some time, no well-developed reactor exists which efficiently
utilizes the rapid-reaction regime. Some of the basic reasons for this appear
to be a lack of adequate gas/solid injection and mixing technology, difficulty
in meeting chemistry and residence time requirements, and agglomeration and
plugging of the reactor. Hydrogenation of raw bituminous coal usually re-
sults in agglomeration, so that typical fluidized bed or moving bed reactors
cannot be used as heretofore described. In addition, the requirement of
short residence time (less than 1 sec) necessarily restricts the reactor to
an entrained flow type. By maintaining rapid mixing, heat-up, and reaction
of the coal near the point of injection and hot reactor walls, the agglomera-
tion problem can be avoided. The uniform and precise mixing of extremely
l~O~Q68
76R18
large feed streams in time of a few milliseconds is the special accomplish-
ment of large rocket engine injectors and one of the principal objects of the
present invention.
Summary of the Invention
It is an object of this invention to convert coal particles entrained
in a gas in a dense phase to hydrocarbon liquids and gases by hydrogenating
the coal particles.
More particularly, it is an object of this invention to utilize rocket
engine injection and mixing techniques in an entrained flow reactor to rapidly
mix and react a separate stream of heated hydrogen with a dense phase stream
of pulverized coal at ambient temperature to produce liquid and gaseous hydro-
carbons.
It is yet another object of this invention to build and operate a high-
temperature, coal liquefaction reactor which minimizes secondary oil and tar
decomposition reactions by optimum control of gas-phase residence time, and
prevents reactor plugging from coal agglomeration by very rapid dispersion
and reaction of the coal while maintalning the internal reactor wall at high
temperature.
A coal liquefaction method and apparatus to produce hydrocarbon liquids
and gases by hydrogenating pulverized coal with hydrogen by flowing pulverized
coal particles entrained in a gas such as hydrogen in a dense phase in a coal
flow conduit at ambient temperature toward an injector adjacent to a reaction
chamber and a heating means is provided for heating a separate source of
hydrogen. The dense phase pulverized coal is injected through the injector
into the reaction chamber followed by injecting the heated separate source of
hydrygen gas through the injector into the reaction chamber and means to
separate the ambient temperature dense phase coal particles and the heated
hydrogen prior to injection of the dense phase coal and the heated hydrogen
llOQ~68
76R18
into the reaction chamber to prevent premature hydrogenation of the pulverized
coal. A quenching means is provided adjacent the reaction chamber to rapidly
arrest the hydrogenation process at a predetermined ti~e period when the re-
action products exit the reaction chamber, and a collecting means is provided
for collecting the reaction products.
The coal is fed to the reactor at nearly its bulk density so that the
quantity of entrained gas is minimized, and the heated hydrogen brought in
separately provides the heat source needed to raise the coal rapidly to re-
action temperatures.
An entrained flow reactor using rocket engine injection and mixing tech-
niques to react a stream of hot hydrogen with a stream of pulverized coal was
designed, built, and operated. As an example only, typical reactor operating
conditions were 1000 psig, 1100F, ~150 milliseconds residence time, and
0.36 lb H2/lb coal. Approximately 19% of the coal carbon was converted to a
synthetic crude oil having a boiling range of 200-350C and a heating value
of 15,800 8TU/lb, 9% to gas containing methane, ethane, and carbon oxides,
and 3~,' to organic compounds in the quench water. The coal throughput rate
WdS approximately 33,000 lbs/hr ft2 reactor cross section or 11,000 lbs/hr
ft3 reactor volume. The products of reaction were rapidly quenched to 220F
in a distance of 1 ft using large flowrates of water through spray nozzles.
Thus, an advantage over the prior art is the use of rocket engine in-
jection and mixing techniques to rapidly mix and react a stream of entrained
coal with hot hydrogen to produce liquid and gaseous hydrocarbons.
Another advantage of the present invention over the prior art is the
minimization of secondary oil and tar decomposition reaction by aptimum con-
trol of gas-phase residence time by very rapid coal partic1e dispersion and
reaction of the coal while maintaining the internal reactor wall at high
temperature.
00~68
76Rl8
Yet another advantage over the prior art is the prevention of coal ag-
glomeration upstream of the reaction chamber by transporting the entrained
dense phase coal in a gas at ambient temperature.
Still another advantage over the prior art is the ability to use a
carrier gas other than hydrogen for transporting the coal partic1es in a dense
phase to the injector thus minimizing explosion hazards in the coal feed sys-
tem due to hydrogcn leakage to the atmosphere from moving mechanical parts
such as valves buildup of explosive mixtures of hydrogen and air in the coal
containing vessels and loss of hydrogen through venting when lock hoppers
are used.
A still further advantage over the prior art is the immediate quenching
of the hydrogenated coal particles as they exit the end of the reaction cham-
ber thereby maximizing the product yield of liquid and gaseous hydrocarbons
Another advantage over the prior art is the direct hydrogenation of coal
particles in a reacticn chamber as opposed to heating the exterior wall of a
tube surrounding the hydrogen and coal particles contained within the tube.
The above-noted objects and advantages of the present invention will be
more fully understood upon the study of the following description in con-
junction with the detailed drawings.
Brief Description of the Drawing
FIG. 1 is a fl~lsheet schematic of the coal liquefaction apparatus;
FIG. 2 is a detailed cross-section of the principal elements of the in-
vention;
FIG. 3 is an enlarged partially cross-sectioned view of the hot hydrogen
and t~e coal flo~ coupling upstream ~ the injector;
FIG. 4 is an enlarged cross-section of the concentric injector;
FIG. 5 is a view of the heater coil element and electrical coupling ad-
jacent the reaction chamber and coal flow tubes;
FIG. 6 is an alternative view of the reaction chamber illustrating di-
~be
verging walls from the injector fdce to the exit plane of the reactor~;
l~OOQ68
FIG. 7 is an alternative view of an injector illustrating
a four-on-one injection pattern; and
FIG. 8 is a view taken along lines 8-8 of FIG. 7.
Description of the Preferred Embodiments
Referring now FIG. 1, a coal liquefaction unit generally
designated as 10 consists of a nitrogen supply system generally
designated as 12 that serves as a purge supply source as well as
a pressurizing source for a quench water tank system generally
designated as 14.
A high pressure coal feeder generally designated as 16
comprises a cylindrical vessel 18 suspended from a load cell 20.
The coal feeder 16 is charged by flowing coal from a low pressure
conical tank 22 through a tube 24. To charge the high pressure
coal feeder 16, the conical tan~ 22 is pressurized to about
55 psig with nitrogen from supply system 12, a ball valve 26 at
the conical tank bottom is quickly opened wide, and the coal
flows in a dense phase through the tu~e 24 to the coal feeder 16.
The excess nitrogen vents out of the coal feeder through a dust
filter 28. After the coal feeder 16 is charged, the tu~e 24
is disconnected and capped as shown at 27, and the dust filter
28 is disconnected and the pressure relief line 32 connected
in its place as shown in FIG. 1. A hopper hydrogen feed line
30 from a hydrogen source 48 or inert gas from an inert gas
source 50 is opened for subsequent operation. Load cell 20
readings before and after charging indicate the quantity of
coal in the feeder. The bottom 19 of the coal feeder 16 is
conically shaped with a 30 included angle to provide smooth
discharging of coal. Coal is fed to the reactor assembly by
opening a ball valve 34 and flowing in a dense phase through a
feed line 36. The hydrogen or inert gas pressure in the coal
feeder is maintained, for example, about 60 to 70 psi higher
than in the reactor assembly generally designated as 38 so
as to provide the driving force for feeding the coal to the
-- 10 --
llOOQ6~ '
reactor assembly 38. The weight of hydrogen carried in the
coal as a percent of the coal flowrate is about 0.5% when the
reaction chamber pressure is 1000 psig. In the case of inert
transport gas, the weight percent transport gas will vary
according to gas density. The flowrate of coal is about .15
pound per second and the flowrate of hydrogen is about .0075
pound per second where hydrogen is used as the carrier gas.
Load cell readings are printed during a test so that the coal
feed rate can be continuously monitored (not shown). When the
10feeder ball valve 34 is in a closed position, nitrogen from
nitrogen supply system 12 flowing through a line 4~ is purged
through the feed line 36 to keep it clear and to prevent the
coal side of the injector ~FIG. 4) from overheating. The
portion of the coal feed line passing through a top flange 37
and making up part of an injector assembly 92 ~FIG. 3) is
typically fabricated from stainless steel. Details of the r
injector assembly 92 are shown in FIGS. 3 and 4.
Pressurized water for a quench system generally designated
as 42 is supplied by, for example, a 150 gallon pressurized
20quench water tank system 14. The flow of water can ~e accurately
measured continuously during tests and is varied by changing
the pressure on the water tank from nitrogen supply system 12.
AccuratP flow control is possible because the pressure drop
across spray nozzles 106 CFIG. 2) is normally a~out 180 psi. In
addition, there is about another 130 psi in pressure drop ahead
of the spray nozzles.
It would be obvious to use fluid other than water to quench
the hydro-genated products as they exit the reaction chamber
such as steam, oil or cold gas ~hydrogen).
There are three gas supply systems, one for nitrogen, one
for hydrogen and one for an inert gas The nitrogen supply
system 12 supplies the nitrogen bleed to a preheater assembly
39 through a conduit 31 and reactor pressure shells 53, and for
-- 11 --
13`00Q68
purging the coal feed line through line 40. The flows are
controlled by using sonic nozzles (not shown) and varying the
pressure upstream of the nozzles to obtain various flowrates.
The hydrogen source 48 supplies the high pressure coal feeder
16 and the preheater assembly 39. The hydrogen flow to the
coal feeder 16 is on demand and is only measured with an
orifice (now shown). The gas supplied to the coal feeder 16
need not be hydrogen from hydrogen source 48 but may be an
inert gas such as nitrogen, carbon dioxide or mixture thereof
from inert gas source 50. The hydrogen flow to the preheater
assembly 39 is controlled by a sonic nozzle an-d upstream
pressure regulator (not shown). The hydrogen system may be
set up so that nitrogen can be used in place of hydrogen for
purging and leak checks(not shown).
Product gas from a spherical catch tank 52 flows through
a conduit 54 to a liquid separator tank 56 and then through a
back pressure regulator system. After the product gas is let
down in pressure, the flowrate is measured using an orifice
and then the gas goes to a burn~tack 58 through a tu~e 60. A
gas sample bottle system generally designated as 62 is connected
to the high pressure side through a line 64 of the gas sample
bottle system 62 and is vented back into the system t~rough a
line 66 to burnstack 58. The sample ~ottle valves 68 are
automated to open in sequence a~out every 30 to 60 seconds
during a test.
The liquia product letdown is controlled by a tank liquid
level control system generally designated as 70 that actuates
an on-o~f valve 72. The flow out of catch tank 52 is regulated
~y a linear plug valve 74. The linear plug valve 74 is
basically a variable orifice that is used to prevent the liquid
from surging out of catch tank 52 so fast that pressure control
in the reactor assembly 38 is upset. A header of three valves
76 is used to select which of drums 78 is to receive the liquid
- 12 -
product.
A more detailed drawing of the hydrogen preheater assembly
generally designated as 39 is presented in FIGS. 2 and 5 and
of the reactor assembly generally designated as 38 is presented
in FIG. 2. The hydrogen preheater assembly is contained within
a pressure shell 41 and the preheater coil 43 is a stainless
steel tube through which an electric current is passed as
hydrogen passes through it. The preheater coil 43 is thin
walled and small in diameter at end 45 and heavy walled and
larger in diameter at end 47. As the hydrogen enters end 45
it is relatively cool and as it progresses down through
helical-shaped preheater coil 43 it heats up and expands. The
variable I.D. and wall thickness of the coil compensates for
this expansion of hydrogen. Seven motor-generator sets [not
shown) supply about 600-800 amps to copper stud conductors 77
and 79 connected to plate 80 through the wall 49 with a power
input up to 150 Kw. The heat transfer from the resistively-
heated wall 49 to the pressurized hydrogen entering end 45
o preheater coil 43 through hydrogen feed line 30 is excellent
and has demonstrated efficiencies of about 99%. Since the tube
wall strength is very low at the heater operating temperatures
(the wall is about 200~F hotter than the hydrogen at the exit
47 of the tube 43), the preheater coil 43 is contained in a
pressure shell 41 made from, for example, carbon-steel pipe and
600 lb flanges 82 and 84. The void space 86 in the pressure
shell 41 is stuffed with, for example, a very low thermal
conductivity insulation 87 such as ~ibrefrax, a product of
Carborundum Corporation, Refractories and Insulation Division,
Fibrefrax Branch,Niagara Falls, New York, and is purged
continuously with about 5 SCFM of nitrogen at about 1000 psig.
The copper stud conductors 77 and 7g, plate 80, and inlet end
45 of the preheater coil 43 are electrically isolated from the
pressure shell 41 and serve as the positive connection to the motor
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1100(~68
generator sets, The ground connection is made to another end
51 of the pressure shell 41 through the blind stainless steel
flange 88 that is sandwiched between the two carbon steel,
weld-neck flanges 84 and 85. A thermocouple 90 is immersed
in the gas exiting the preheater assembly 39, and a pressure
transducer (not shown) is connected to a similar port in the
flange.
In a similar fashion, referring to FIG. 2, the reactor
tube 98 and injector assembly generally designated as 92 are
enclosed in a pressure shell 53 so that the hot reactor tube
walls 94 experience very little stress while at high temperature.
The reactor tube is supported by the insulation 87 and slip
fits through a hole in the insulation support plate 96 so that
thermal elongation of the reactor tube 98 is allowed. The
preheater assembly 39 is connected to the in~ector assembly 92
via a stainless steel coiled tube 100. This tube is coiled
so that it can thermally elongate without applying a force
against the injector assembly 92, possibly bowing the reactor
tube 98. The reactor tube 98 and injector assem~ly 92 can
easily be removed from the pressure shell 53 by removing the
top flange 37 and a small amount of insulation 87. Several
bosse~ 102 along the side of the pressure shell 53 permit
thermocouple measurements along the reactor outside wall, and
one directly inside the bottom of the reactor tube 98 near exit
plane 99.
The quench zone lQ4 consists, for example, o~ 3 rows of 4
full-cone spray nozzIes lQ6 that screw into the quench zone
pipe wall 108 from the outside. As the reaction products exit
the reactor tube 98, they are quenched immediately with water
sprays supplying water at about 3 to 6 gpm. Enough spray
water is used to reduce the product temperature to about 200 ~F.
The li~uid, gas, and solids are forced down into spherical
catch tank 52 (FIG. 1~ where the gas separates and exits. The
- 14 -
iioo~68
liquid level control system 70 (FIG. 1) is used to maintain a
liquid level in the spherical catch tank 52 and to let down
the slurry product into drums 78 ~FIG. 1). Vent line 71
connects to the liquid level control system 70.
FIGS. 3 and 4 illustrate in more detail the injector
assembly 92 and reactor tube 98 combination wherein a stream
of hot (1500-2000F) hydrogen is reacted with a stream of
pulverized coal. The injector assembly generally designated
as 92, for example, consists of a housing body 110 that is
separable from a coal feed line assembly 112 and the reactor
tube 98 by a pair of, for example, AN type nuts 114 and 116.
The coal feed line assembly 112 consists of 3 tubes, an outer
shell tube 130, an insulation tube 118, and a post tube 120.
The post tube 120 is 3/8 inch O.D. (Dimension "D" FIG. 4) x
0.083 inch wall, 321 stainless steel. A 0.55 inch length of
end 121 of the post tube 120 is machined to form end 121 to
0.254 inch O.D. (Dimension "I" FIG. 4) x 0.020 inch wall. The
entire injector assembly 92 is contained within the pre~sure
shell 53 (FIG. 2). The pos* tube 120 extends through top
flange 37 via a packing gland fitting such as a 3/8 inch Conax
fitting 105 made by Conax Corporation of Buffalo, New York, and
is coupled with coal feed line 36 outside of the pressure shell
53. End 121 of the post tube 120 extends concentrically within
a separate cone 122 that is connected to housing body 110 by
AN nut 116. An annulus 124 (FIG 4) is defined between inner
wall 123 of cone 122 and outer surface 125 of end 121 of post
tube 120. Annulus 124 is 0.350 inch O.D. with a gap of 0.048
inches (Dimension "G" FIG. 4) to the outer surface 125 of end
121 of the post tube 120. End 121 is recessed 0.212 inch
(Dimension "F"). Three wire spacers 117 are brazed to end 121
to center the post tube 120 and end 121 in the annulus 124.
The post tube 120 is supported as it passes through a plate 115
by a 3/8 inch Conax fitting 135 that is screwed into plate 115.
- 15 -
110~6~ '
The insulation tube 118 is 1 inch O.D. x .049 inch wall, 321
stainless steel and terminates at end 119 in a cone that
diverges toward but is not affixed to the outer wall of the
post tube 120 near end 121. End 113 of tube 118 is affixed to
plate 115. An annulus 126 is defined by an outer surface 127
of tube 120 and an inner surface 128 of tube 118. The annulus
126 is filled with insulation material 87. The outer shell
tube 130 is a structural member that houses concentric tubes
118 and 120 and connects at a first end 132 to plate 115 and
at the other end 134 to housing body 110 by nut 114. Tube 130
is 1.5 inch O.D. x .049 inch wall, 321 stainless steel. An
annulus 136 is defined by an outer surface 138 of tube 118 and
an inner surface 140 of housing body 110. The annulus 136
serves to direct a hot hydrogen exterior port 111 toward
annulus 124 and out injector assembly 92 (FIG. 4). An annulus
131 is defined by outer surface 138 of tube 118 and inner
surface 129 of tube 130 and is filled with insulation 87 that
is kept from falling in annulus 136 by a sleeve 133. The
reactor tube 98 (FIG. 3) is 1.5 inch O.D. x .049 inch wall
(Dlmension "B'~, 321 stainless steel tube, is 3 feet long
(,Dimension "A"), and i$ connected to the housing body 110 by
nut 116. The overall injector assembly 92 is about 1 ft long
(Dimension "C").
In operation, the coal liquefaction plant functions in the
following manner: A pulverized bituminous coal such as Kentucky
hvAb may be utilized. Other types of pulverized coal such as
lignite and sub-bituminous may also be used. The coal is
typically 70% less than 74 microns in size ~200 mesh coal) and
is fed into high pressure coal feeder 16. The average coal
particle size is 40 to 50 microns. A quarter inch line approxi-
mately 20 feet long directs dense phase coal from valve 34 into
post tube 120 outside of top flange 37 towards the injector
assembly 92. The pressure shells 41 and 53 are pressurized
- 16 -
1~0~68
with nitrogen to approximately 1000 psig from nitrogen supply
system 12. Typically, a 70 psi differential between coal
feeder 16 and the pressure shells 41 and 53 is maintained to
encourage coal flow in a dense phase through feed line 36 into
the injector assembly 92. In other words, the pressure within
the coal feeder is approximately 1070 psig during operation.
In this specific example hydrogen from hydrogen source 48 is
directed towards the coal feeder 16 through hydrogen feed line
30 and the ratio of hydrogen to coal is about 0.005 lbs of
hydrogen per pound of coal. Obviously, an inert gas may be
utilized in place of the hydrogen with the pulverized coal
from inert gas source 50 to the coal feeder 16. Hydrogen is
additionally fed from hydrogen source 48 through a conduit 29
into the hydrogen preheater assembly 39. The hydrogen is
directed into a 321 stainless steel preheater coil 43 at end
45. The coil 43 at end 45 is 1/4 inch O.D. x .035 inch wall
and as the helix progresses down the coil 43 it transitions
into a 5/16 inch O.D. x .049 inch wall coil and from there into
a 3/8 inch O.D. x .083 inch wall coil. The hydrogen exits coil
43 at end 47 towards coiled tube 100 which directs hot hydrogen
into the injector assembly 92. The hydrogen flowrate is 10 to
50 percent of the flowrate of dense phase coal. The coil is
about 260 inches long in this example. The hydrogen is typically
fed into coil 43 at the rate of .025 lbs per second. At startup
the dense phase coal is flowed through feed line 36 into the
post tube 120 outside top flange 37 and into the injector
assembly 92 followed by introduction of hot hydrogen through
the preheater coil 43. The hydrogen exits the heated coil in
a temperature range between 150Q and 2000F (a typical tempera-
ture is 1~50F~ adjacent the injector assembly 92. Typically,
in the foregoing example the reaction temperature within the
chamber by reactor tube 98 is found to be about 1100F with a
residence time of the pulverized coal within the reactor tube 98
~1001~68
of about 150 milliseconds when the hot hydrogen flowrate is
0.36 lbs of hydrogen per pound of coal. The reaction time in
reactor tube 98 may be between 10 and 500 milliseconds for the
hydrogenation process. As can be seen from the above, with a
typical reaction temperature of about 1100F and a hydrogen
temperature range of 1500-2000F, the hydrogen temperature is
from 400 to 900F in excess of the typical reaction temperature.
It i9 desirable to promote better mixing to assure that hot
hydrogen moves past the coal particles within the reactor tube
98. For example, the hot hydrogen velocity exiting the injector
assembly 92 is approximately 1000 ft/ second while the velocity
of the dense phase entrained coal exiting the injector is about
7 ft~second. Within these parameters approximately 19 to 20
of the coal carbon is converted into a synthetic crude oil
having a boiling range of about 200-350C and a heating value
of 15,800 BTU per lb, 9% to gas containing methane, ethane,
and carbon oxides, and about 3% to organic compounds in the
quench water. The coal throughput rate is approximately 33,000
lbs per hour ft reactor cross-section or 11, ooa lbs per hour
ft3 reactor volume. The products of reaction are rapidly
quenched to about 225F downstream of exit plane 99 of reactor
tube 98 in a distance of about 1 ft, the reaction products
passing by water spray nozzles 106 in the quench zone below the
reaction chamber defined by reactor tube 98. The water flowrate
through the multiplicity of water spray nozzles is from 2 to 6
gallons per minute. The products are then moved into the catch
tank 52 and from there to the various drums 78 where the solids
are collected the ga~ and by-products being directed into
separator tank 56 and the by-products being directed through
burnstack 58.
It would be obvious to use other means to heat the hydrogen
being separately directed to the injector assembly 92 other than
use of high electrical current to heat up a coil which is trans-
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68
porting the hydrogen. For example, a conventional fuel fired
furnace or heater could be utilized to heat up a coil tube
containing hot hydrogen. Many other methods to heat hot
hydrogen are within the state of the art.
Turning now to FIG. 6 an alternative reactor tube 141 is
illustrated wherein one end of the reaction chamber connected
to the injector assembly 92 at end 142 begins a diverging wall
section which diverges towards end 144 adjacent plate 146.
The diverging walls defining a reaction chamber 150 tend to
discourage sticking of the partially hydrogenated products
passing through the reactor tube 141, thus minimizing any
tendency to plug.
FIGS. 7 and 8 disclose a different type of injector commonly
known in the rocket engine field as a four-on-one injector. The
injector consists of a center post 154 which transports dense
phase coal particles and is supported within an upper plate
156 and a bottom injector plate 160. The inner face 157 of
plate 156 and the inner face 158 of injector plate 160 define
an annular chamber 162 which directs hot hydrogen entering a
conduit 164 from the preheater assembly into the chamber. A
thermal insulator 159 is provided around the post center 154
so that coal particle~ transported within center post 154 are
not prematurely heated. The injector plate 160 has drilled
therein a series of four orificés 166 equidistantl~ spaced
around the injector ~FIG. 8) each of the orifices having an
impingement angle with respect to the center line of the center
post 154 of approximatély 30 which facilitates greater mixing
of the minute coal particles exiting center post 154 with the
- impinging hot hydrogen downstream of the injector face. FIG. 8
better depicts the xelationship of the orifices with respect to
the center post 154.
It would be obvious to configure any num~er of gas streams
on the central coal stream with different impingement angles,
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1100068
all of which are well within the state-of-the-art particularly
in the rocket engine field.
It will, of course, be realized that various modifications
can be made in the design and operation of the present
invention without departing from the spirit thereof. Thus,
while the principal preferred construction and mode of operation
of the invention have been explained and what is now considered
. to represent its best embodiment has been illustrated and
described, it should be understood that within the scope of
the appended claims, the invention may be practiced otherwise
than as specifically illustrated and described.
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