US3477942A

US3477942A - Hydrocarbon fuels from coal or any carbonaceous material

Info

Publication number: US3477942A
Application number: US656954A
Authority: US
Inventors: Neal P Cochran
Original assignee: US Department of the Interior
Current assignee: US Department of the Interior
Priority date: 1967-07-28
Filing date: 1967-07-28
Publication date: 1969-11-11
Anticipated expiration: 1986-11-11

Description

Nov. 11, 1969 N. P. COCHRAN HYDROCARBON FUELS FROM COAL 0R ANY CARBONACEOUS MATERIAL Filed July 28, 1967 5 Sheets-Sheet l u wn:

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man WH on. mzmmuom ...o uw. IIILIIII n 3G mm n kwh United States Patent O 3,477,942 HYDROCARBON FUELS FROM COAL OR ANY CARBONACEOUS MATERIAL Neal P. Cochran, Frederick, Md., assigner to the United States of America as represented by the Secretary of the Interior Filed July 28, 1967, Ser. No. 656,954 Int. Cl. Cg 1/06; C103 3/18; H01m 27/30 U.S. Cl. 208-10 6 Claims ABSTRACT OF THE DISCLOSURE In the pyrolysis or hydrogasification of coal wherein the coal is converted to fluid products and hot solid char the improvement comprising passing a first portion of char to a fuel cell or magneto-hydrodynamic device to produce D.C. current and passing a second portion of char to an internal resistant reactor wherein the char isreaeted with steam to form a producer gas containing hydrogen using a portion of the D.C. current produced to control the heat input to the reactor.

This invention resulted-from work done by the Office of `Coal Research of the Department of the Interior, and the domestic titleto the invention is in the Government.

BACKGROUND OF INVENTION Field of invention This invention relates to the treatment of coal `for the recovery of valuable hydrocarbon materials. More particularly, the invention concerns an arrangement whereby the hot char from a coal pyrolysis or hydrogasication is used-to produce, in combination, electricity and producer gas containing hydrogen.

Description of the prior art The present invention comprises a new and improved process for the conversion of coal into valuable volatlle hydrocarbon fluids wherein said coal is treated to produce fluid' hydrocarbons and hot char and which a first portion of hot char is converted into electricity and a second portion is contacted with steam in an electrogasication reactor. Alternately, all the hot char may be contacted with steam in the electrogasification reactor With a portion q of the gas being converted to electricity.

This process results in a uniquely efficient system requiring only coal, Water and air as inputs and which is susceptible to modifications whereby a wide variety of valuable hydrocarbons may be produced.

Accordingly, the objects of this invention are:

t To provide a new and improved process for the treatment of coal.

To provide a method for producing valuable hydrocarbons from coal which requires inputs of only coal, air and water.

:To provide a method for efliciently using the char from a coal pyrolysis or gasification process, and to provide an improved coal conversion process which produces valuable volatile hydrocarbon fluids and excess electricity.

ICC

Other features and advantages of the present invention will become clear on reading the following description wherein reference is made to the accompanying drawings in which:

FIG. 1 represents a schematic flow diagram of a combined pyrolysis, power recovery, gasification and hydrogenation treatment of coal designed to recover a variety of valuable hydrocarbon fluids.

FIG. 2 schematically represents an internal flow diagram for a high temperature fuel cell such as shown in FIG. l.

FIG. 3 schematically represents a combined hydrogasifcation, electrothermal gasification and power recovery process utilizing a high temperature fuel cell, whereby coal is converted to valuable pipeline gas.

FIG. 4 schematically represents a process similar t0 that shown in FIG. 3 -but using a lower temperature fuel cell.

FIG. 5 is a schematic flow diagram of a process similar to that shown in FIG. 1 except that the` power recovery portion of the process includes a magneto-hydrodynamic system.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to FIG. 1T there is shown a process for the production of a variety of valuable fuels from coal. In that figure, reference numeral 1 is a pulverized or finely divided coal feed which if necessary is heated in a fluid bed at from about 60G-750 F. to prevent subsequent agglomeration. The size of the coal should permit fluidization in bed 2 where the coal is treated at from about 800950 F. for a residence time of about 10 t0 60 minutes with a gas stream 3 consisting predominately of nitrogen. This treatment results in a dried and preheated lcoal stream 6 and an overhead l4 which may be either vented, or collected and condensed, or recycled as S to bed 2.

The predried coal stream 6 is led to a second fluidized bed 7, operating in a range of from about 1l00-1200 F. There it is held for a residence time of from l0 to 60 minutes so that pyrolysis occurs and volatiles 9 are driven off as the predried feed 6 is contacted. with a hot gas stream 8.

A partially pyrolized eoal stream 10 is fed from uidized bed 7 to fluidized `bed 11 where it is contacted with a high temperature hydrogen stream 12 at about 1500 F. to 1600 F. again for a residence time of from l0 to 60 minutes. The volatiles driven off in this bed form stream 8 which is sent back to bed 7.

A portion 14 of the char product from bed 11 is fed into uidized reactor 1S where it is in contact with a steam input 16 at about 2500 F. to produce a gas stream 17 comprising carbon monoxide and hydrogen. Reactor 15 is of the internal resistance type, that is, the reactor is equipped with electrodes across which an electrical potential is maintained. When the reactor is fluidized with conductive char particles electric energy is supe plied and the temperature of the bed can be raised to a reactive level and a high degree of temperature control can be maintained. Reactors of this type are described in U.S. Patents 1,857,799; 2,921,840; 2,968,683 and 2,978,315. Exiting reactor 15. stream 17 is sent to a treatment at 18 where it is cleaned in a conventional manner such as by `condensing and separating to remove impurities, shifted with steam to carbon dioxide and hydrogen and then passed through a conventional carbon dioxide ab sorber resulting in a stream 19 consisting of carbon monoxide and of hydrogen. A portion of 19 is sent back as stream 12 to bed 11.

The remaining portion 20 of the char product from bed 11 serves as the input to a high temperature fuel cell 21 which operates in the range of from about 1000 C. to

3 1100 C. In this cell, which is described in Office of Coal Research Report No. 17 entitled, Review and Evaluation of Project Fuel Cell, char 20 and air 21a are in the inputs and a nitrogen containing gas 22, power 23, spent gas 24 and ash 25 are the outputs, Clean gas 26 is recycled as well as a partially spent gas 27.

The operation of this high temperature cell will be more fully understood as reference is made to FIG. 2.

There, char 20 is fed to reactor 28 where it is contacted with a gas Amixture 27 com-prising carbon monoxide, hydrogen, carbon dioxide and water vapor such that the concentrations of carbon monoxide and hydrogen are about equal to the concentrations of carbon dioxide and water vapor respectively.

The reaction of gas 27 with the char reduces the concentration of CO2 and H2O and increases the concentration of CO and H2 forming a clean gas stream 26. Ash 25 resulting from this reaction may be discarded or sent to a mineral recovery (not shown). Stream 26 is fed to the fuel electrode 29 of a first cell bank 30. In this cell, oxygen from air stream 21a takes on two electrons and enters the electrolyte as an ion leaving a deficiency of electrons on the air electrode 31 giving that electrode a positive charge. The oxygen ions then pass through the electrolyte and combine with the incoming CO to form CO2 and the incoming H2 to form H2O there'by depositing two electrons on the fuel electrode 29, When connected, in circuit, electrons iiow from the fuel electrode 29 to the air electrode 31 giving a power output at 23. An oxygen depleted air stream 22 consisting predominantly of nitrogen is withdrawn from the air side, and a partially spent fuel stream 27 is withdrawn from the fuel electrode side of the cell. A rst -portion of the latter is recycled to the reactor where the CO and H2 content is increased and a second portion forms the feed to the fuel electrode 32 of a second cell bank 33. As with the first cell bank, air 21 is fed to the air electrode 34 causing current to flow from electrode 32 to electrode 34. Nitrogen 22 is withdrawn from the air side and a spent gas 35 rich in CO2 and H2O is withdrawn from the fuel side.

Returning now to FIG. 1 the refining of hydrocarbons takes places as volatiles 9 from hed 7 are sent to an oil recovery 36 where they undergo condensation and separation by a water quench. Depending upon the condition of the stream at that point, it may also be subjected to an acid treatment, an alkali treatment, or both. Following such treatments the petroleum extract may be sent via 47 to a refining stage or via 37 to a hydrocracking unit 38 where it is contacted with hydrogen containing stream 39. Depending upon the extent of cracking and the use of other conversion processes such as reforming, hydrogenation, isomerization, etc., a variety of products can be recovered. Gaseous products exit via 44 and are sent to a gas recovery unit 45 where they undergo clean-up condensation and if necessary separation into propane and butane fractions by distillation. Other recoverable products include number 6 oil, 40, number 2, oil, 41, JP-S fuel, 42, and gasoline, 43.

Alternatively, hydrogen and carbon monoxide from stream 19 may be diverted to form methane or methanol. To produce methane at 50, the carbon monoxide and hydrogen in stream 48 are. contacted at elevated temperatures over a methanation catalyst such as Raney nickel in a tube wall reactor 49 causing the following reaction If a methanol product 52 is desired, the gases in line 48 are passed over a conventional hydrogenation catalyst in a reactor 51 causing the following reaction to occur:

CO-l-ZHW CH3OH Of course, the concentrations of carbon monoxide and hydrogen in stream 48 should be adjusted to provide optimum proportions for the methanation or hydrogenation processes.

When large amounts of methane or methanol are desired, the product from oil recovery 36 will generally be sent to a refinery as crude via 47 unless some alternative source of hydrogen is available for refining purposes.

A hydrogasification process according to the present invention is described in FIG.'3- There, coal 100 which if necessary has undergone a heating treatment to reduce caking and prevent agglomeration, is introduced into a hydrogasification unit 101 of the type described in Ofiice of Coal Research Report entitled Process Designand Cost Estimate for Production of 265 Million s.c.f./ day of Pipeline Gas by the Hydrogasification of Biturninous Coa This unit is countercurrent, solids-downow reactor having an upper free-fall devolatization zone 102 operating at from about 900-1300 F. at about 1000 to 2000 p.s.i.a. and a lower moving tbed Zone 103 where the char from the upper zone is contacted with upwardly directed'streams of hydrogen 104 and steam 105 at a'reaction temperature of about 1700 F. The hydrogen reacts with the carbon to form methane, and the steam reacts with carbon and carbon monoxide to form hydrogen and carbon oxides. The ratio of moles HZ/moles steam shoul be approximately 1. i

^ The volatile products exit via 106 and any entrained fines are separated in a cyclone 107 and returned through 108 to section 103. J

The volatiles pass through cyclone 107 and line 109 to a cleanup and methanation process 110 of the type previously described. This process results in a discard stream 111 of carbon dioxide, hydrogen sulfide and water vapor and a product pipeline gas 112 having an energy value of about 940 B.t.u./s.c.f. The char produced in the hydrogasifier is split into two

streams

113 and 114. The former is introduced in an internal resistance reactor 115 where it is contacted with steam 116 to form a mixture of carbon oxides, hydrogen, water vapor and some hydrogen sulfide. This mixture is led via 117 to a conventional clean-up at 118 where carbon dioxide, water vaporl and hydrogen sulfide are removed and vented through line 119. The cleaned portion 120 consisting essentially of hydrogen goes to a water gas shift reactor 121 where it is contacted with steam 122. The product of that reaction 123 comprises a mixture of hydrogen, water vapor and carbon dioxide which is passed to a further clean-up at 124 where the carbon dioxide and water vapor 125 are removed leaving a gas consisting essentially of hydrogen. A portion of this hydrogen 104 furnishes the feed to hydrogasier 101. Excess hydrogen 126 and the remaining portion of char 114 from the hydrogasier comprise the fuel feeds to a high temperature fuel cell unit 127 of the type previously described with reference to FIG. 2. The reaction of these fuels with air 128 produces an intermediate recycle stream 129 comprising hydrogen, carlbon monoxide, carbon dioxide and water vapor; ash 130; an oxygen depleted gas consisting primarily of nitrogen 131, power 132, and an off-gas 133 consisting mainly of water vapor and carbon dioxide .but containing some carbon monoxide and hydrogen. v

This olf-gas may be recycled to clean-up 118 to conserve the hydrogen and carbon vmonoxide content, whereas the D.C. power 132 supplies'the electrical energy requirements of reactor 115. Any excess power 133 may be used to supply in-plant needs. l

-A similar system designed to produce pipeline gas is shown in FIG. 4. There, coal 200 which may be pretreated to prevent agglomeration is reacted in a hydrogasifier 201 of the type previously described, with incoming streams of hydrogen 202 and steam 203. The volatile products exit the hydrogasifier through 204 and pass through'cyclone 205 where lines are removed and sent back to the hydrogasifier via 205a. The volatiles are then processed at 206 for clean-up and lmethanation as described with reference to FIG. 3 to produce an off-gas 207 containing carbon dioxide, water vapor and hydrogen sulfide and a pipeline gas 208. l

The char produced in hydrogasier 201 is sent via line 209 to an internal resistance reactor 210 where it comes into contact with steam 211 resulting in the formation of ash 212 and a high temperature hydrogen and carbon monoxide containing gas 213. Heat may be recovered from this gas for internal process use. For example, FIG. 3 shows that it may be used to heat stea'm 203 in exchanger 214. Following this heat removal step, the gas is purified at 215 by conventional means to remove hydrogen sulfide, water vapor and carbon dioxide. The resultant stream 2 16 is divided such that a portion 217 flows through a turbine power generator unit `218 and then into a fuel cell 219. This type of cell has in the past been called a high temperature cell but, for the purposes of this disclosure it will be termed a low temperature cell as its operating range 60G-700 C. is much lower than the solid electrolyte type fuel cell describe'd with reference to FIG. 2.

Fuel cell 219 is of the molten carbonate type familiar to the art. Cells of this type are fully described in Hydrocarbon Fuel Cell Technology edited by B. S. Baker, Academic-Press, 1965. A detailed flow plan of a molten carbonate fuel cell using a mixture of hydrogen and carbon monoxide as a source of fuel, air as anoxidizer and water as a coolant is shown on page 275 of that publication. A simplified flow plan is described in FIG. 4. Air 220 is fed to cell to react with the hydrogen and carbon monoxide feed 217. A portion of the fuel is oxidized to water vapor and carbon dioxide 222 which are removed from effluent 221 in a conventional purification stage 223. The remaining unoxidized fuel is recycled to the cell via 224. Spent air is vented at 225 and the power 232 produced in the cell furnishes the energy requirements for internal resistance reactor 210. Water 227 is used as a coolant for the cell and is thereby converted to high pressure steam 226. A portion 211 of this steam is supplied to reactor 210 for reaction with char 209. A second portion 226a may be recycled either to stream 203 or may be used as the input to a water shift reactor.

A reactor of that type is shown as 228. A portion 229 of the hydrogen and carbon monoxide of stream 216 is used as a feed to the water shift reactor along with steam 230. The product of the reaction is a stream 231 consisting essentially of hydrogen which is purified at 232 to remove most of the water vapor and carbon dioxide which may be present thus forming a product of substantially pure hydrogen 202 which is used as the input to a hydrogasier 201.

Referring now to FIG. S there is shown a process similar to that described with reference to FIG. 1 but wherein there is employed a MHD device for converting char from the coal pyrolysis into electrical energy for internal process use.

In this process coal 300, treated if necessary to prevent agglomeration, is fed as in FIG. l to a three stage pyrolysis. In the rst stage 301 coal 300 is contacted with a continuously recycled gas stream 302 for about to 60 minutes at a temperature in the range of about 60G-750 F. The heated coal 303 then enters the second stage 304 where it is brought into contact at 1100- 1200 F. for a residence time of from about 10 to 60 minutes with a hot gas stream 305. This contact results in the liberation of volatiles 306 which are processed as in FIG. l at an oil recovery 307, a hydrocracking unit 308 and a gas recovery and processing unit 309 to recover methane 350 and liquid products 360. The hot solids 310 from stage 304 pass to the third stage 311 where they are reacted with hydrogen at 1500-1600 F. from about 10 to 60 minutes. The gases 305- resulting from this contact provide the input to the second reactor 304 while the hot solid char is divided into

streams

312 and 313. Portion 312 enters internal resistance reactor 314 wherein it is brought into contact with high pressure steam 315 to form hydrogen containing gas 316. This gas is shifted to form additional hydrogen and cleaned up to remove 46 carbon dioxide, hydrogen sulfide and water vapor at 317. The resultant hydrogen stream 318 is divided into two

streams

319 and 320. The former comprises the gas feed for the third stage 311 of the pyrolysis stages whereas the latter is directed to unit 308.

Char 313 is combusted with air 321 and an ionization promoter 338 such as sodium, potassium or cessium in burner 322 and ash 323 is withdrawn.. The remaining products of combustion 324 pass through a magnetohydrodynamic device 325 where power 326 is produced. Devices of this type which operate either as a Faraday generator oraccording to the Hall effect are known in the art. The MHD unit used in the present invention may, for example, be of the type described by Rosa in U.S. Patent 3,182,213, designed to produce D.C. power. Other types may however be used as, for example, that disclosed by Brill in U.S. Patent 3,189,768 designed to produce A.C. power.

The hot gases 327 from the MHD device pass through

heat exchangers

328 and 329 where they are exchanged with a compressed air stream 330 in the rst instance to form heated air 321 for burner 322 and water 331 in the second instance to form high pressure steam 332. A portion 315 of steam 332 may provide the feed to reactor 314 while the remainder is fed to a turbine 333 driving a compressor 334 which compresses an air stream 335. The condensate 336 from turbine 333 can be recycled to provide water for heat exchanger 329.

After gases 327 have been cooled in

heat exchangers

328 and 329, they are fed to a clean-up and recovery unit 337 in which the promoter 338 is recovered and recycled to burner 322 and a cooled ue gas 339 is vented.

A portion 340 of the power 326 produced in the MHD device is provided to reactor 314 to satisfy the energy requirements of the steam-carbon reaction, while the remaining portion 341 is applied to either for in-plant or commercial use.

Thus while preferred embodiments of the invention have been described, it is to be understood that various other embodiments wherein various known processes may be applied to the hydrocarbons recovered to form other valuable products are also contemplated.

What is claimed is:

1. In a process wherein coal is contacted with a hydrogen containing gas at high temperatures whereby said coal is converted into valuable hydrocarbon fluids and solid char the improvement comprising (a) passing a rst portion of said char to an internal resistance reactor zone;

(b) contacting said first portion of char in said internal resistance reactor zone with steam;

(c) passing a second portion of said char to a second reactor zone;

(d) oxidizing said second portion of char in said second reactor zone to form gaseous combustion products;

(e) passing said gaseous combustion products through a zone wherein electrical energy is produced directly from said gaseous combustion products; and

(f) passing a portion of said electrical energy produced in step (e) to said internal resistance reactor zone of step (a).

2. The process of claim 1 wherein a hydrogen containing gas is recovered from said internal resistance reactor zone and a portion of said hydrogen containin gas is brought into contact with said coal.

3. The process of claim 2 wherein a portion of said hydrogen containing gas is brought into contact with a portion of said valuable hydrocarbon uids. l

4. The process of claim 1 wherein said electrical energy is produced in a high temperature fuel cell zone.

5. The process of claim 1 wherein said electrical energy is produced in a magneto-hydrodynamic zone.

7 y 6. 'In a process wherein coal is contacted with a hydrogen containing gas whereby said coal is converted into valuable hydrocarbon uids and solid char the improvement comprising (a) passing said solid char to an internal resistance reactor-,zone wherein it is treated with steam to form a hydrogen containing gas;

(b) contacting said coal with a rst portion of said hydrogen containing gas;

(c) passing a second portion of said hydrogen containing gas to a low temperature fuel cell zone wherein it is oxidized thereby producing electrical energy; and

(d) passing a portion of said electrical energy produced in step (c) to said internal resistance reactor zone of step (a).

8 References Cited UNITED STATES PATENTS OTHER REFERENCES B. S. Baker, Editor, Hydrocarbon Fuel Cell Technology, Academic Press, 1965, p. 275.

DELBERT E. GANTZ, Primary Examiner V. OKEEFE, Assistant Examiner U.S. Cl. X.R. 13 6-86