CA1080974A - Gasification of hydrocarbon feedstocks - Google Patents

Abstract

GASIFICATION OF HYDROCARBON FEED STOCKS
Abstract of the Disclosure Hydrocarbon feedstock is first vaporized in the presence of hydrogen and then the vaporized hydrocarbon feedstock together with excess hydrogen, is gasified to form an effluent gas consist-ing essentially of methane and aromatic hydrocarbons together with hydrogen and minor amounts of hydrogen sulfide. The process is suitable for the production of a pipeline gas having a heating value of approximately 1,000 BTU/SCF by further processing the effluent, after separation of the aromatic fraction and hydrogen sulfide from the gasifier effluent; the effluent is subject to cryogenic separation of the hydrogen with the hydrogen being re-cycled to the gasification step and the methane being discharged into a product pipeline. The overall process contemplates re-vaporization of the aromatic fraction separated from the effluent and regasification to extinction of this fraction. Preferred feedstock are crude oil, bitumen produced from tar sands, shale oil,liquid volatiles resulting from coking of coal, liquiefied coal resulting from solvating coal with a solvent and hydrogen, aromatic hydrocarbons, naphtha, gas oils, crude oil distillates, and crude oil residues.
It is contemplated that the gasifier effluent could be used as a feedstream for the production of a hydrogen-carbon monoxide synthesis gas, hydrogen, carbon monoxide or as a source of fuel to be burned in place of oil or other liquid hydrocarbons.

Description

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This invention pertains to processes for gasifying hydrocarbon feedstocks to form -an effluent consisting essentially of methane, and an aromatic fraction which is substantially benzene and to the production of synthetic natural gas (methane) by the gasification of hydrocarbon feedstock. Hydrocarbon feedstocks are vaporized in the presence of hydrogen and then with an excess of hydrogen are reacted at high temperature to produce an effluent gas containing essentially methane, aromatics, acid gases such as hydrogen sulfide and excess hydrogen. In one aspect of the invention the effluent from the gasification step is then further processed by condensing and~or absorbing out the aromatic fraction, removing the acid gases and finally, separating the hydrogen from the methane to produce a synthetic natural gas (SNG) having a heating value of approximately 1,000 BTU/SCF. The resulting synthetic natural gas can be discharged into a storage receptacle or put into a pipeline for use by residential communities or industrial concerns.- The aromatics removed from the gasifier effluent are revaporiæed and recycled to the gasifier for reaction to extinction. The acid gases containing mainly hydrogen sulfide are reacted to produce -elemental sulfur.
The gasifier effluent, is suitable as a plant fuel or ~
feedstream for further processing into a hydrogen-carbon mono- ~ ;
xide synthesis gas or hydrogen gas.
Gasification of hydrocarbon feedstocks, mainly drude oil and crude oil fractions, to produce a synthetic pipeline gas either rich in hydrogen or rich in methane is shown by many processes in the prior art.
U.S. Patent 3,870,481 discloses and claims a process for producing synthetic natural gas from crude oil which encom-." ".

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passes vaporizing a substantial portion of the crude oil at a temperature of between 600 and 1,000F, thereafter introducing the vaporized crude oil and hydrogen gas into a gasification vessel maintained at a temperature in excess of l,000F wherein the Eeedstream is gasified producing an effluent consisting essentially of hydrogen, hydrogen sulfide, methane, ethane and residual aromatic hydrocarbons; thereafter cooling the effluent gas stream to ambient temperature and recovering the waste heat, drying the effluent and removing the hydrogen sulfide and resi-dual aromatics from the effluent, cryogenically separating themethane and the ethane from the hydrogen and thereafter reacting the ethane with steam to produce additional methane and carbon dioxide and removing the carbon dioxide from the steam. The two methane streams are combined and discharged into a product pipeline or storage vessel. -After developing the process embodied in U.S. Patent 3,870,481, new discoveries were made and the process of the ` ' present invention devised wherein excess hydrogen is used and the temperature of the gasifier is maintained at a temperature level in excess of 1500F, to gasify the aromatics in the feed-stocks and to suppress-the formation of ethane, thus increasing the methane content of the gasifier effluent. Thus a process had been developed wherein heavy crude oils and other hydro-carbon feedstocks could be successfully gasified and the gasifier effluent could be processed to produce a synthetic natural gas.
It was also discovered that if the aromatic removed from the ~`
gasifier effluent were revaporized and recycled to the gasifier, these aromatics could be gasified to methane and the net pro- `
duction of aromatics could be reduced or eliminated.

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One typical hydrocarbon feedstock for::the process .
could have the following characteristics: .. .
1. A gravity of 10 API. .

2. A metal content of 350 ppm of vanadium. .

3. A sulfur content of 3~.
It is contemplated that hydrocarbon feedstock for the . .
process of the present invention will come from heavy:crude oils which are now shut-in because of limited market demand due to ~.
their inherent characteristics, bitumen produced from tar sands, . .:.:
shale oil, liquids produced from coal using new lique~action ....
and hydrogenation technologies now under development, volatiles :-from the coking of coal, aromatic hydrocarbons, naphtha, ~as :.
oils, crude oil distillates and crude oil residues. In view of ;~
the current world situation involving natural gas shortag.es and the existence of large reserves of bitumen, the process of the present invention will, in the future, be of increasing import- ~. .
ance.
While the process of the present invention is suitable for gasifying conventional crude oils, it is primarily designed for those types of heavy hydrocarbon feedstocks which must be considered the source of future synthetic natural gas. Crude oils with high metal contents, particular-ly; vanadium, are ex-tremely detrimental to catalysts used in conventional oil refin- .
eries for manufaaturing gasoline. Heavy oils also generate large volumes of residues tbottoms) that become difficult to -utilize when a conventional process, depending upon catalytic : .
conversion, is used. Heavy hydrocarbon feedstocks processed by thermal rather than catalytic techniques provide overall process economies. ~:~
Crude oil is a heterogeneous mixture of hydrocarbon .
compounds... It was found that the ability to hydrogasify .`

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(gasify in the presence of hydrogen) a given oil fraction in a gasifier is affected by the nature of the hydrocarbon compound introduced into the gasifier. It has been discovered that when operating the gasifier at a temperature below 1500F, with a gasifier feedstream containing a fraction of heavy polycyclic hydrocarbons (characterized as having a high boiling point and as being highly aromatic), that these fractions tended to pass `
through the gasifier without substantial gasification (reaction).
Furthermore, it was found that the effluent from the gasifier contained these unreacted polycyclic oil compounds and that the ~-recovery of waste heat in a waste heat boiler from the effluent stream of the gasifier was impossible because these polycyclic compounds are tarry in nature and when condensed would foul the surface of the heat exchanger. Thus, quenching of the effluent -directly out of the gasifier was required resulting in a loss of overall thermal efficiency.
In order to overcome these problems and provide an improved process it was discovered that by increasing the temp-erature of the gasifier to a temperature above 1500F and pre-ferably about 1600F while maintaining a pressure of 600 psig, that these heavy polycyclic oil compounds could be gasified in the presence of hyrdrogen ~(hydrogasified). The gasifier - ~ -effluent is substantially methane with very little ethane ;
(gasification reaction below 1500F produces substantial ethane~
Furthermore, it was found that the aromatics in the effluent ;
were free of the heavy tarry polycyclic compounds and consisted of compounds which were mainly benzen~. The effluent from the hydrogasification reactor (hydrogasifier) was thus suitable for waste heat recovery since this could be accomplished without ~-fouling of the waste heat boiler surfaces.
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With the process of the present invention aromatic compounds in the gasifier effluent can be removed and recycled back to the gasifier as a vapor for conversion to methane or used in other process schemes as needed. By controlling the recycle stream, the process can be run with no net production of aromatic compounds.
The process of the invention yields an effluent with-out formation of substantial amounts of carbon in the process reactor by maintâining sufficiently high concentration of un~

reacted hydrogen in gasifier effluent. It was found necessary to maintain a minimum unreacted hydrogen content in the effluent gas at the desired operating conditions of about 65% by volume in order to prevent substant~al carbon formation in the gasifier.
The principal advantage of our discovery and process resides in the method of gasifying heavy hydrocarbon feedstocks containing heavy polycyclic oil compounds to produce essentially methane and light aromatics such as benzene and to recycle these aromatiCS to extinction to produce only methane, if desired.
This makes possible the use of hydrocarbon feedstocks which exist in large volumes in the world but which were not hereto-fore considered suitable for use in this manner.
Furthermore, there is shown a one-step method for pro-ducing substantially methane from a hydrocarbon feedstream wherein waste heat boilers can be used for heat recovery when heavy polycyclic compounds are contained in the feedstream.
Thus in accord with another aspect of the present invention, a process for producing synthetic natural gas having a heating value of approximately 1,000 BTU/SCF from hydrocarbon feedstocks can be achieved by vaporizing the hydrocarbon feed-stock in the presence of hydrogen and then injecting thevaporized hydrocarbon .' ~ .....

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feedstock together with excess hydrogen into a gas recycle hydro-generator (GRH) operated at a minimum pressure of 75 psig such as disclosed by the British Gas Corporation (formerly British Gas Council) in U.S. Patent 3,363,024. The GRH reactor is an adia-batic open vessel reactor with a concentric draft tube into which the hydrogen/oil vapor is injected. Gas recirculation within the reactor is caused by jetting the reactants into the draft tube, whereby the gases within the reactor are entrained with the newly injected reactants. Operating the reactor at a minimum pressure of 75 psig and at a temperature in excess of 1500 F.
in combination with the high recirculation rate ensures that the injector vapor is brought to reaction tempearture in a matter of -milliseconds. The hydrogen/oil vapor mixture reacts to produce a gasifier effluent consisting essentially of methane, aromatics and acid gases together with a large amount (approximately 65%) of free hydrogen. After removal from the reactor, the hot effl-uent can be cooled to ambient with heat recovery for use elsewhere in the process. Cooling of the effluent can be accomplished by any known methods 1ncluding a combination quench and cooling. ~;
During heat recovery the condensible aromatics are condensed and removed from the effluent stream. Subsequently, the acid gases and noncondensible aromatic fraction are removed from the effluent thus producing a product stream consisting essentially of methane and hydrogen. The methane is separated from the hydrogen by cryogenic techniques and is ready for use as a synthetic natural gas. The hydrogen is recycled to the gasified for use in gasify-ing the hydrocarbon feedstocks.
Another suitable reactor is the Fluidized Bed Hydro-generator (E'BH) developed by the British Gas Corporation and dis-closed in U.S. Patent 3,124,436. This reactor operates on a simi- ~ ~ -lar principle as the GRH except that hot carbon particles are recirculated with the gas. The hot recirculating carbon parti-cles would serve to supply heat to the feedstream which would -7f`~
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be introduced into the reac-tor, operated at a pressure in excess of 300 psig as specified by patentees and at a temperature in ex-cess of 15500F. in accord with our invention, as hydrocarbon-hydrogen vapor.
The aromatic condensate is composed primarily of ben-zene and naphthalene with small quantities of heavier compounds.
In one aspect of the invention the condensate is revaporized and returned to the reactor.
BRIEE' DESCRIPTION OF THE DRAWINGS
Fig. 1 is a block diagram illustrating the process of gasifying hydrocarbon feedstocks according to the present invention;
Fig. 2 is a block diagram illustrating an alternate pro-cess according to the invention utilizing liquefied coal, prepared as part of the process, as a feedstock;
Fig. 3 is a schematic flow diagram of a plant embodying the process of the invention for producing synthetic natural gas;
Fig. 4 is a plot of GRH Reactor Temperature against volume percent of ethane in the reactor effluent.
Referring to Figure 1, the overall process according to the invention, is shown in block form. In Figure 1, arrow 10 includes the hydrocarbon feedstock which is selected from those materials such as crude oil, bitumen produced from tar sands, shale oil, liquid volaties resulting from coking of coal, lique- ~ -fied coal resulting from solvating coal with a solvent and hyd-rogen, aromatic hydrocarbons, naphtha, gas oils, crude oil dis-tillates and crude oil residues. In the one stage gasification step 12 the hydrocarbon feedstock is preheated to about 700F.
and vaporized in the presence of hydrogen which is initially heated to a temperature in excess of 750F. in accord with the vaporization technique disclosed in U.S. Patent 3,870,481. Other vaporization methods can be used so long as such methods provide a vaporized hydrocarbon feed. The vaporized hydrocarbon and excess hydrogen feed are introduced into the single stage gasi-1,': ~ .

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fier. As set out above, the preferred gasification vessel is that disclosed in U.S. Patent 3,363,024 and commonly referred to as a -gas recycle hydrogenerator (GRH). ;
However, any gasification vessel is suitable so long as :~
the feedstream is heated rapidly (less than one second) to temp-erature and the feedstream is allowed to dwell at temperature for a long enough time period (greater than one second) so that the overall gasifier effluent consists essentially of methane, aromatic compounds (mostly benzene), unreacted hydrogen in the : : ......
amount of at least 40~ by volume of the effluent together with minor amounts of ethane, ethane compounds, ethylene, propane, propylene and hydrogen sulfide if sulphur is present in the feedstock.

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The hydrocarbon feedstock and hydrogen are injected into the gasifier, recirculated, and reacted to form an efflu-ent stream shown by arrow 14 consisting essentially of methane, aromatics, hydrogen sulfide and excess hydrogen. The effluent is cooled to ambient temperature in the purification section 16 thus condensing out the condensible aromatics which are primarily benzene and naphthalene. Removal of the residual aromatics and hydrogen sulfide is accomplished by a purification process such as disclosed in U.S. Patent 2,863,527. The process disclosed in this patent is known commercially as the Rectisol Process marketed by Lurgi Mineralol Technic GMbH, Frankfurt Am Main, West Germany.
After the gasifier effluent 14 passes through the purification section 16 a product stream designated by arrow 18 containing essentially hydrogen and methane, is subjected to a cryogenic separation designated by block 20. In the cryogenic separator the hydrogen is separated from the methane yielding a synthetic natural gas stream consisting essentially of methane (designated by arrow 22). While cryogenic separation of the hydrogen is preferred, other techniques for hydrogen removal can be used. Among these are pressure swing adsorption and gas diffusion through a membrane. The synthetic natural gas stream consists essentially of methane with minor amounts, e.g., less than 2~ of hydrogen and ethane.
The condensible aromatics consisting essentially of benzene and naphthalene (designated by arrow 24) are recycled to the vaporizer for revaporization and gasification. The condensible aromatics are continuously recycled in this manner until extinguished thereby eliminating the production of by-products which may be undesirable or uneconomical to produce. ;~

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The hydrogen sulfide separated out in the purification section and designated by arrow 26 is conducted to a sulfur plant which embodies the Claus Process as is well known in the art. The Claus Process is discussed in detail in an article by V. W. Gamson and R. H. Elkins entitled "Sulfur From Hydrogen Sulfide" which appeared in Chemic~al Engin~ë~e~ring Pro~gre~ss, Volume 49, Number 4, April, 1953 beginning at page 203. , Hydrogen represented by arrow 28 removed from the cryogenic separation unit is recycled to the gasification step 10 for use in the vaporization of the hydrocarbon feedstock and ' , as excess hydrogen to be added to the gasifier.
Included in the overall process scheme is an oxygen ' plant 30 which produces oxygen designated by arrow 32 for use in a hydrogen plant 34 to produce hydrogen 35 for use in the - ~ , vaporization and gasification of the hydrocarbon feedstock. , The hydrogen plant produces hydrogen by the well known partial oxidation process. The balance of the hydrogen plant 34 includes ,' waste heat recovery systems, water gas shift, acid gas removal ~ ' and methanation systems to produce high purity hydrogen by the ~' 20 reaction of CO and ste-am and subsequent removal of the hydrogen ' sulfide and Co2. CO2 from the hydrogen plant 34 is vented ,~
through a conduit 36 and the hydrogen 35 passed to the process ' stream. Hydrogen sulfide 38 produced in the hydrogen plant 34 is conducted to the sulfur plant where elemental sulfur ~ , -40 is produced.
Figure 2 is a schematic of the process of Figure 1 -`
wherein the process includes the additional steps of prepar,ation and grinding followed by solvating coal to produce a liquefied coal for introduction into the gasifier for gasifidation to produce a synthetic natural gas. In the process of Figure 2 . . : , ,, : :
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there is included a source of coal ~6 which is introduced to a preparation and grinding facility designated by block 48 wherein the coal is finely ground and given an initial separ-ation to remove unwanted gangue materials. The ground coal 50 is introduced to a coal soluation process 52 wherein the coal is liquefied by reacting with a solvent and hydrogen.
The solvation process can be chosen from any of those available or under development such as the P and M Process developed by Pittsburgh and Midway Coal Mining Company and the Consol CSF
Process developed by the Consolidation Coal Company. The liquefied coal 54 together with hydrogen and other gases 56 generated in the initial solvation step are introduced into the vaporizer and the process continues such as described in relation to Figure 1.
In the coal solvation process, nitrogen 58 from the -~ -o~ygen plant 30' can be used as an inerting atmosphere in preparing the coal for solvation.
In the process of Figure 2 it is contemplated that substantially all of the ash from the coal will be removed in the coal solvation step and will not affect the overall process.
Figure 3 is a schematic flow sheet of a plant which would be suitable for producing 150,000,000 standard cubic feet per day of synthetic natural gas from approximately 30,000 barrels per day of a heavy crude oil. The product of the plant described in Figure 3 is a synthetic natural gas containing essentially methane with minor amounts of hydrogen and ethane having a heating value of about 1,000 btu per standard cubic feet and is delivered at 1,000 psig pressure. The plant features ;
recovering sulfur as a by-product. Such a plant would have an expected thermal efficiency of about 78~ and includes six major processing section namely gasification, purification, (comprising '' . ' ' .

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aromatic separation, acid gas, removal, shift and carbon dioxide removal? cryogenic separation, oxygen supply, hydrogen supply and sulfur recovery. Such a plant is designated to be self- , sufficient by incorporating a combined cycle power generation system and all required off-site areas.
When in operation, a hydrocarbon feedstock such as , heavy crude oil, hydrogen and recycled aromatic condensate are fed to the gasification section to produce a 600 psig gasifier ' effluent (containing aromatic liquid condensate) and a residual ~, oil fraction. ''''~
In the schematic diagram of Figure 3 the process flows throughout the system are designated by the arrows shown. , . . ~ .
The hydrocarbon feed 60 is introduced to the vapor- ~ ' izer 62 through suitable intermediate conduits by means of ' pump 64 and oil preheater 66 wherein the oil is raised to a , temperature of about 700~F. Hydrogen and recycled aromatics (arrow 73) are introduced to the vaporiæer 62 through hydrogen preheater 68 and waste heat recovery boiler 70 wherein the temperature of the hydrogen is raised to a level in excess of 750~F. In one type of vaporizer hot hydrogen is sparged into the hydrocarbon feedstock beneath the liquid level in the vaporizer. The vaporized hydrocarbon feedstock and excess hydrogen then flows as indicated by arrow 70' to the gas recycle hydrogenator (GRH~ 72 wherein the gasification of the hydrocarbon feedstock takes place. Hydrogen and recycled aromatics introduced through a conduit 74 are used to control temperature in the GRH 72, ~s described previously, the GRH
reactor 72 is an adiabatic open vessel reacotr with a concent-ric draft tube into which the hydrogen/hydrocarbon vapor is injected. Gas recirculation within the reactor is caused by ' jetting the re,actants into the draft tube whereby the gases '' " ~:

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within the reactor are entrained in the reactant stream. Re-circulation rates within the reactor of approximately 10 ~o 20 times the injected vapor volume may be obtained using this device. The high recirculation rate of hot gases, combined with the temperature of greater than 1500~F in the G~I assures that the injected vapor is brought to reaction temperatures in a matter of milli-seconds. The hydrogen-feedstock vapor mixture reacts to produce primarily methane, aromatics and hydrogen ~ ;
sulfide. With the hydrogen/oil vapor inlet temperature fixed, the temperature within the GRH is controlled by a gas recycle stream consisting of hydrogen and/or recycle aromatics which prevents overheating of the GRH reactor due to the exothermic hydrogenation reactions. Approximately 65~ of the effluent from the GRH reactor remains as free hydrogen and this hydrogen is recovered subsequentlv and recirculated back to the vaporizer.
The average residence time for the feedstock in the GRH reactor is 5 to 15 seconds. The hot effluent gases 76 from the GR~I
reactor are cooled to ambient by passing through a waste heat recovery boiler 70 oil preheater 66 and conduit 78 to the pur-ification unit where the condensed aromatic fraction is recover-ed in the aromatic separator 80. The condensed aromatics are removed from separator 80 by conduit 82 mixed with hydrogen from preheater 68 further preheated by passing through waste heat recovery boiler 70 and introduced to the GRH 72 and/or vaporizer 62 by means of conduit 84 The gasifier effluent after removal of the condensible aromatics is compressed to about 750 psig in recycle compressor 86 to permit further processing and recycling of the hydrogen. The effluent from recycle compressor 86 consists primarily of hydrogen, methaner ethane and hydrogen sulfide saturated with benzene. The ~' i ': ': . :

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effluent 88 is scrubbed with a non-volatile oil to remove residual benzene in oil absorber ~9 and then scrubbed with a 22% diethanolamine solution in a packed tower 92. The die-thanolamine (DEA) is regenerated in the acid gas removal system of the hydrogen supply section. The gasifier effluent thus treated leaves the DEA column at about 120F and is cooled to approximately 40F in precooler 94 The oil used to remove benzene is stripped of the benzene with a portion of recycled `
hydrogen, as will subsequently be discussed, at about 175 and 700 psig in oil stripper 96. The oil is then cooled to about 100F and recirculated by means of pump 98 to the oil scrub column 90. The gasifier effluent precoo~led to about 40F in precooler 94 and containing essentially hydrogen and methane is passed through a dryer 100 to remove water and prevent freeze-out in the cryogenic separation unit 102. In the cryo-genic separation unit 102 the hydrogen is separated from the synthetic natural gas by cooling the effluent to a temperature of about -237F to condense the SNG. Refrigeration is supplied by flashing the product to relatively low pressures and rewarm~

ing the recycle and product streams against the feed. The SNG
product is recompressed in product compressor 104 to the desired product pressure and conducted to the point of use, e.g., ~ ~
pipéline or storage. ~ -The separated hydrogen 106 is conducted through pre-cooler 94 back to the gasification section of the process. ~-The recycled hydrogen is conducted back to the gasif-ication unit through conduits 106, 108, 110 to the hydrogen preheater. Portions of the recycled hydrogen can be withdrawn for e~ample by a conduit designate~d as arrow 112 and used to ~ -remove the benzene from the oil in oil stripper 96. The re-covered benæene and hydrogen from oil stripper 96 is returned to the recycle ;

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stream by a conduit 114. ~ -In addition to the gasification unit, the necessary sup- -port systems are also shown in Figure 3. The first of such systems is an air separation unit generally encompassing an air plant 116 wherein air is liquefied and separated into nitrogen and oxygen. A portion of the oxygen product is liquefied and taken by a suitable conduit to a storage vessel 120. Gaseous oxygen is recovered from the air plant 116 and introduced through suit-able conduits designated 122, 124 to the hydrogen plant. Gaseous oxygen can be stored in a suitable vessel 126 and additional oxygen added from the liquefied storage vessel 120 through suitable heaters and pumps such as 128. Gaseous oxygen is then fed through conduit 124 to a plurality of reactors 130 wherein the oxygen and residual oil from vaporizer 62 are reacted with steam at about 800 psig and 2,600F. to produce a crude synthe-sis gas. Each reactor, commonly referred to as a partial oxi-:. . .
dation or POX reactor produces a crude synthesis gas. The re- -actor effluent is cooled in an adjacent waste heat boiler (not shown) producing 1,300 psig. steam. Entrained soot produced in reactors 130 which is about 3 weight percent of the feed oil is removed by water scrubbing in scrubbers 132 and will be re- -cycled to the process. Carbon recycle will take place in a re-cycle reactor generally designated 134 which is offered commer-cially by the Shell Oil Company. The water slurry is contacted with vigorous agitation with naphtha in reactor 134 thus extract-ing the soot from the water phase by retaining the soot in the hydrocarbon phase. The naphtha is then mixed with the feed to ~-the reactors 130 and after stripping the naphtha for recycling the carbon remains as a slurry in the feed oil.
The product of the hydrogen plant 136 is a mixture of carbon monoxide and hydrogen with about 6% CO2 and about 1% ~

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and H2S are scrubbed from the gas by a carbonate solution cir-culating continuously between absorber and regenerator towers.
The solution at the bottom of the absorber 138 after reduction of pressure from 690 psia to about 8 psig is conducted by a conduit 140 to a carbonate stripper 142 where steam stripping is carried out at about 240F thus liberating the acid gas contained in the solution. The hot solution is conducted from the carbonate stripper 142 via pump 144 back to the carbonate absorber 138 to complete the circulating solution circuit. The effluent from the carbonate absorber 138 containing about 0.5~
C2 and 0.2% H2S together with the carbon monoxide and hydrogen is air cooled (not shown) and conducted by conduit 145 for further scrubbing by a DEA solution circulating continuously between a DEA absorber 147 and a DEA stripper 146. The bottoms from the stripper 146 are pumped through a heat exchanger (not shown) for cooling to 120~F and returned to absorber 147 to ~--''' : .
complete the circuit. The DEA regeneratore acid off-gas passes ;

through the carbonate regenerator via conduit 150 and the com-b~ned acid gas stream is cooled, compressed and transferred to a reaction furnace 152 and converter 154 for conversion to elemental sulfur which is withdrawn at 156. The reaction fur-nace and converter 152~ 154 respectively are part of a con-ventional Claus plant.
The purified hydrogen/CO gas from the acid gas removal unit is conducted to a shift unit via suitable conduits 158. A .
portion of the hydrogen/CO synthesis gas mixture can be with-drawn to use as fuel for running the plant as designated by arrow 160. The hydrogen/CO mixture introduced to the shift unit is conducted through a conventional shift converter wherein the CO is con-verted to hydrogen by the conventional shift reaction. Initially, the H2/CO syn gas mixture is passed through a gas saturator wherein the necessary water vapor is added to the gas. The pH of the water is automatically controlled in the range of 7.5-8.5 to neutralize the effect of corrosion from the carbon dioxide water mixture. The saturator effluent 162 has steam added to it through a conduit 164 as needed to adjust the N2O/CO ratio for shift. The syn gas is conducted to a high temperature shift converter 166 containing a conventional iron-chrome base material which has been known for many years. From the high temperature shift converter 166, the gases are conducted to a zinc oxide desulfurizer 168 which is used to prevent any traces of sulfur from penetrating to the low temperature shift converter 170 next to the stream. The low temperature shift converter 170 con-tains a copper based catalyst that will reduce the carbon mono-xide level to about 1%. Such catalysts have been known in the art for more than 10 years.
The effluent from the low temperature shift converter is cooled through a suitable cooler 172 and then passes through a carbon dioxide removal unit similar to those previously des- -cribed in conjunction with the purification and acid gas removal units. The final purification unit consists generally of the same hot carbonate process used in the first acid gas removal unit except there is included, in addition to the carbonate ~
absorber 174 carbonate stripper 176 and pump 178, a methanator ;~ -180. The primary process differences are removal of CO2 only, rather than the combination of CO2 and hydrogen sulfide, and addition of a methanator for reduction of carbon oxides to the desired levels in the hydrogen product from the total facility~
The CO2 removal unit receives crude hydrogen from the shift unit.

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In this unit the carbon dioxide will be removed and remaining traces of CO2 and CO will be-methanated.
The effluent from methanator 180 is conducted into the recycle conduit 110 as shown by arrow 182. The foregoing describes a process that will produce a synthetic natural gas having heating value of approximately 1,000 btu per standard cubic foot in quantities of approximately 150,000,000 standard cubic feed per day.
Several tests were run to verify the expected results of a process built in accordance with the foregoing description.
One method of running tests was in accord with the system described in Figure 3 of the U.S. Patent No. 3,870,481 An identical test set up was used and the results from running Kuwait Topped crude oil and benzene in such a test setup are set forth in Table 1. Kuwait Topped crude oil as received had the minus 360F fraction removed prior to running the test.

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From the foregoi~g it is o~vious that the gasifier operating at a temperature in excess of lSQ0 and with excess hydrogen is effective to suppress~ethane formation and to provide an effluent that is substantially-methane and hydrogen.
The benzene runs were accomplished with total vapor- -~
ization of the benzene hydrocarbon feedstock in the vaporizer before it was injected into the gasifier. The extent of vaporization of the hydrocarbon feedstock will depend upon its composition, For example with the Topper Kuwait crude oil used in the tests the operation was optimized when approximately 75% of the topped crude oil was vaporized, Lighter feedstocks such as naphtha would completely vaporize while the heavy crude oils and heavy crude-like materials such as bitumen produced from tar sands, shale oils, and solvated coal would only be partially vaporized at these process conditions. -Parallel tests~:,were run in a pilot plant operated by the British Gas Council at Solihull, England with the GRH
operating at elevated temperature and with excess hydrogen using Topped Kuwait crude oil as set forth in Table II, and a Monagas crude oil as set forth in Table III. Monagas crude oil is a Venezuelan bitumen believed to be suitable as an ~-alternative feedstock.
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D ~ E~ . X X X m ~ x ~ ~.2 --From the foregoing Tables II and III, it is obvious that the elevated temperature operation of the gas recycle ..... ..
hydrogenerator combined with the use of excess hydrogen produces a gasifier effluent that is substantially methane. The forma-tion of ethane is effectively suppressed and carbon formation is also minimized.
Table IV sets forth the data from three experimental runs conducted to show that when the gasifier temperature is ~ -maintained above 1550F, the ethane content in the effluent is less than 5 mole percent. The comparative runs set out in Table IV show that for a given feedstock, e.g. No. 2 fuel oil, when the GRH temperature dropped from 1555 F. (Run F2G-08) to 1400 F. (Runs F2G-09 and F2G-10) the ethane content of the effl-uent went from 4.6? by volume (mole percent) to over 15% by . . . . .
volume (mole percent). ~;
TABLE IV
-- . , .: .
VAPOR~ZER - GR~I Tests G~H ~ erating Temperature i400-1555 F.
Test Data No. 2 Fuel Oil Feedstock 350-600 Vaporizing 2 Pressure, PSIG Conden-Productsate Vap. GRH Composition TW % of Run Run Time Temp. F. GRH Temp. Press. Volume % GRH
No. Hrs. (Mean Wall) F. (Effluent H2 O1l;Feed F2G-08 11 730 1555 600 36.3 4.6 56.4 21.4 F2G-09 11 680 1400 350 25.1 15.6 54.8 27.0 F2G-10 11 695 1400 400 26.5 15.9 52.5 26.8 ~ - - ' ~ ' The data from TabIes I-IV, along with data reported in U.S. Patent 3,363,024, 3,591,356 and 3,870,481, together with test .. : .
data reported by the British Gas Council (now British Gas Corp-oration) in a document entitled "The Hydrogenation of Oils to -.
Gaseous Hydrocarbons" identified as Research Communication GC122 ~-of the Gas Council, November 1965 is shown in the graph of ~'ig-ure 4 of the drawing wherein reactor temperature is plotted against the volume percent of ethane in the reactor ef~luent.
Figure 4 also shows tne temperature limits of various prior art , -23-.

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_ patents drawn to gasification of hydrocarbon feedstocks. Thus it is readily apparent from the data of Table IV and the plot of Figure 4 that when the gasifier (reactor) is operated at temp-eratures in excess of 1550F., the ethane content of the efflu-ent is below 5 volume percent (mole percent).
Several tests have been run using liquids derived from coal with similar results.
Lighter oils have also been run successfully however if lighter oils were available, the process could include a topp-ing tower and a Catalytic Rich Gas unit to process the lighterfractions such as disclosed in U.S. Patent 3,870,481. This would reduce the investment in the hydrogen producing area because of the reduced size of the partial oxidation system and oxygen plants.
The process of this invention can be used for the pro-duction of hydrogen, carbon monoxide, or hydrogen and carbon mon- ~
oxide rather than for the production of SNG. Currently the major ~ -portion of the hydrogen, carbon monoxide, or hydrogen and carbon ~-monoxide produced together is by the catalytic steam reforming of ;;-natural gas. These products can also be produced by partial oxidation of heavier hydrocarbon feedstocks with oxygen and steam in a partial oxidation gasifier. Where natural gas is in short supply, heavier hydrocarbon feedstocks will have to be utilized ~-for producing hydrogen or hydrogen and carbon monoxide. Partial oxidation of heavier feedstocks is substantially more expensive than steam reforming natural gas. The present invention can be adapted to produce hydrogen, carbon monoxide, or hydrogen and carbon monoxide from heavier hydrocarbon feedstocks without the use of a partial oxidation gasifier. The method of the present invention for producing hydrogen from a heavy hydrocarbon feed -~

stock is utilized by gasifying the feedstock in the one stage gasification reactor to produce an effluent which is purified to give a product stream of gases that are essentially methane and hydrogen. This product stream is then mixed with steam and :Y . .

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catalytically reformed to carbon monoxide and hydrogen in a steam reformer using this well known technology. A relatively pure stream of hydrogen can be produced by further reacting the ,~
carbon monoxide with steam over a bed of shift catalysts while maintaining different operating conditions and then purging this stream of the carbon dioxide formed. Part of this hydrogen pro-duce can be recycled back to the one stage gasification reactor, thus avoiding the use of partial oxidation while gasifying a heavy hydrocarbon feedstock.
If carbon monoxide is desired, the gas from the re-former is not shifted but is separated by well known technology into its components and a portion of the hydrogen is recycled.
It is within the scope of the invention to utilize -mixed feedstocks such as mixtures of different crude oil fractions, ~-.: .
crude oil and coal derived liquids and the like. ;

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Claims (18)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method of producing an effluent stream consisting essentially of methane and an aromatic fraction consisting essent-ially of benzene from a hydrocarbon feedstock selected from the group consisting of crude oil, crude oil fractions, bitumen from tar sands, shale oil, liquids resulting from the pyrolysis of coal, liquified coal produced from solvating coal with a solvent and hydrogen, and mixtures thereof comprising the steps of:
vaporizing the feedstock by heating the feedstock in the present of hydrogen at a temperature below 1000°F
and at a pressure greater than 75 psig; and rapidly heating the feedstock vapors and hydrogen to a temperature in excess of 1550°F. and at a pressure greater than 75 psig and maintaining said feedstock at a temperature and pressure for a time sufficient to cause said feedstock vapors to react with said hydrogen to form an effluent consisting essentially of methane, an aromatic fraction containing primarily benzene, unreacted hydrogen, together with less than 5 mole percent ethane and minor amounts of ethylene, propane, propylene and hydrogen sulfide.

2. A method according to claim 1, wherein said efflu-ent is cooled to recover heat thus condensing a major portion of the aromatic fraction; and said condensed aromatics are removed from said effluent.

3. A method according to claim 2, wherein the uncon-densed aromatic fraction together with the hydrogen sulfide is removed in a purification zone.

4. A method according to claim 3, wherein said hydro-gen is separated from said effluent and recycled for use in said vaporization or said heating steps.

5. A method according to claim 3, wherein the sep-arated aromatic fractions are returned to the vaporization step for addition to the feedstock and hydrogen fed to the heating step.

6. A method according to claim 1, wherein said eff-luent is cooled to recover heat thus condensing a portion of the aromatic fraction; and said effluent is further processed by:
removing said condensed aromatic portion from said effluent;
passing said effluent through a purification zone to remove said hydrogen sulfide and residual uncondensed aromatic fractions thus producing a product stream consisting essentially of methane and hydrogen; and introducing said product stream to a stream reformer wherein said methane is catalytically reformed in the presence of steam thus producing a product gas con-sisting essentially of hydrogen, carbon monoxide and carbon dioxide.

7. A method according to claim 6, wherein said pro-duce gas is introduced into a shift reactor for conversion of the carbon monoxide to hydrogen and carbon dioxide; and said carbon dioxide is removed from said product gas to produce an end product consisting of substantially pure hydrogen.

8. A method according to claim 1, of producing sub-stantially pure hydrogen from a hydrocarbon feedstock selected from the group consisting of crude oil, crude oil fractions, bit- ;-

Claim 8 - continued umen from tar sands, shale oil, liquids resulting from the pyro-lysis of coal, liquefied coal produced from solvating coal with a solvent and hydrogen and mixtures thereof comprising the steps of:
vaporizing the feedstock by heating the feedstock in the presence of hydrogen at a temperature below 1000°F.
and at a pressure greater than 75 psig;
rapidly heating the feedstock vapors and hydrogen to a temperature in excess of 1550°F. and at a pressure greater than 75 psig and maintaining said feedstock vapors at temperature and pressure for a time suffic-ient to cause said feedstock vapors to react with said hydrogen to form an effluent consisting essentially of methane, an aromatic fraction containing primarily benzene, unreacted hydrogen together with less than 5 mole percent ethane and minor amounts of ethylene, propane, propylene and hydrogen sulfide;
cooling said effluent to recover heat thus condensing and removing a major portion of the aromatic fraction from said effluent;
passing said effluent through a purification zone to remove said hydrogen sulfide and residual uncondensed aromatic fractions thus producing a product stream con-sisting effentially of methane and hydrogen;
introducing said methane and hydrogen product stream into a steam reformer wherein said methane is catalyt-ically reformed in the presence of steam to produce a gas consisting essentially of hydrogen, carbon monoxide and carbon dioxide;
passing said gas through a shift reactor to convert the carbon monoxide to carbon dioxide and hydrogen;
removing said carbon dioxide from said gas thus pro-ducing a gas as an end product which is substantially pure hydrogen.

9. A method according to claim 1, of producing a pipeline gas having a heating value of about 1,000 BTU/SCF from a hydrocarbon feedstock selected from the group consisting of crude oil, bitumen from tar sands, shale oil, liquid volatiles resulting from coking of coal, liquefied coal resulting from solvating coal with a solvent and hydrogen, aromatic hydrocarbons, naphtha, gas oils, crude oil distillates, and crude oil residues and mixtures thereof comprising the steps of:
vaporizing the hydrocarbon feedstock preheated to about 700°F. in the presence of hydrogen at a temp-erature in excess of 750°F. to produce a feedstream of hydrogen feedstock vapors and excess hydrogen;
injecting said feedstream into an adiabatic gasifica-tion vessel maintained at a pressure in excess of 75 psig and a temperature in excess of 1,550°F. where-in the hydrocarbon feedstock vapors are gasified to form essentially methane and aromatic compounds, together with less than 5 mole percent ethane and with minor amounts of ethylene, propane, propylene and hydrogen sulfide in an effluent containing excess hydrogen;
cooling the effluent to recover waste heat and conden-sing a major portion of the aromatic fraction of said gasifier effluent;
separating out said condensed aromatic fraction from said effluent;
removing non-condensible residual aromatics and hydro-gen sulfide from said effluent in a purification zone;
separating the hydrogen from the methane and other light hydrocarbons in the effluent to produce a prod-uct gas consisting essentially of methane;
returning the hydrogen separated from the effluent to the vaporization and gasification units of the process; and discharging said product gas into a product receiving device.

10. A method according to claim 9, wherein the aro-matics separated from said gasifier effluent are returned and injected into said gasifier and said vaporizer.

11. A method according to claim 9, wherein said hy-drogen sulfide is treated to produce elemental sulfur.

12. A method according to claim 9, wherein said hy-drocarbon feedstock is partially vaporized in a vaporization ves-sel which contains a pool of the residual hydrocarbon feedstock from which said residual feedstock is withdrawn and used to pro-duce hydrogen for injection into said vaporizer.

13. A method according to claim 9 wherein said hydro-carbon feedstock is selected from the group consisting of crude oil and crude oil fractions.

14. A method according to claim 9, wherein said hydro-carbon feedstock is liquefied coal resulting from solvating coal with solvent and hydrogen.

15. A method according to claim 9, wherein said hydro-carbon feedstock is bitumen from tar sands.

16. A method according to claim 9, wherein said hydro-carbon feedstock is shale oil.

17. A method according to claim 1 of producing a pipeline gas having a heating value of about 1,000 BTU/SCF from a hydrocarbon feedstock selected from the group consisting of crude oil, bitumen from tar sands shale oil, liquid volatiles

Claim 17 - continued resulting from coking of coal, liquefied coal resulting from solvating coal with a solvent and hydrogen, aromatic hydro-carbons, naphtha, gas oils, crude oil distillates, crude oil residues and mixtures thereof comprising the steps of:
vaporizing the hydrocarbon feedstock preheated to about 700°F. in the presence of hydrogen at a temp-erature in excess of 750°F. to produce a feedstream of hydrocarbon feedstock vapors and excess hydrogen;
injecting said feedstream into an adiabatic gasifica-tion vessel maintained at a pressure in excess of 75 psig and a temperature in excess of 1550°F. wherein the hydrocarbon feedstock vapors are gasified to form essentially methane and aromatic compounds together with less than 5 mole percent ethane and with minor amounts of ethylene, propane, propylene and hydrogen sulfide in an effluent containing excess hydrogen;
cooling the effluent to recover waste heat and conden-sing a major portion of the aromatic fraction of said gasifier effluent;
separating out said condensed aromatic fraction from said effluent;
removing residual aromatics and hydrogen sulfide from said effluent in a purification zone;
revaporizing and recycling said residual aromatics and condensed aromatic fraction to said gasifier and said vaporizer;
separating the hydrogen from the methane and other light hydrocarbons in the effluent to produce a pro-duct gas consisting essentially of methane;
returning the hydrogen separated from the effluent to the vaporization and gasification units of the process;
and discharging said product gas into a product receiving device.

18. A method according to claim 1, of producing a pipeline gas having a heating value of about 1,000 BTU/SCF from a hydrocarbon feedstock selected from the group consisting of crude oil, bitumen from tar sands, shale oil, liquid volatiles resulting from coking of coal, liquefied coal resulting from solv-ating coal with a solvent and hydrogen, aromatic hydrocarbons, naphtha, gas oils, crude oil distillates, crude oil residues and mixtures thereof comprising the steps of:
vaporizing the hydrocarbon feedstock preheated to about 700°F. in the presence of hydrogen at a temperature in excess of 750°F. in a vaporization vessel which contains a pool of the residual hydrocarbon feedstock to produce a feedstream of hydrocarbon feedstock vapors and excess hydrogen;
withdrawing residual feedstock from the vaporization vessel pool and using said residual feedstock to produce process hydrogen by the partial oxidation process;
injecting said feedstream into an adiabatic gasification vessel maintained at a pressure in excess of 75 psig and a temperature in excess of 1550°F. wherein the hydrocarbon feedstock vapors are gasified to form es-sentially methane and aromatic compounds together with less than 5 mole percent ethane and with minor amounts of ethylene, propane, propylene and hydrogen sulfide in an effluent containing excess hydrogen;
cooling the effluent to recover waste heat and conden-sing a major portion of the aromatic fraction of said gasifier effluent, separating out said condensed aromatic fraction from said effluent and revaporizing and recycling said aro-matic fraction to said gasifier and said vaporizer;
removing residual aromatics and hydrogen sulfide from said effluent in a purification zone;
separating the hydrogen from the methane and other light

Claim 18 - continued hydrocarbons in the effluent to produce a product gas consisting essentially of methane;
returning the hydrogen separated from the effluent to the vaporization and gasification units of the process; and discharging said product gas into a product receiving device.