US2756192A

US2756192A - Reforming cycle gas by thermocompressor

Info

Publication number: US2756192A
Application number: US323817A
Authority: US
Inventors: Eric V Bergstrom
Original assignee: Socony Mobil Oil Co Inc
Current assignee: ExxonMobil Oil Corp
Priority date: 1952-12-03
Filing date: 1952-12-03
Publication date: 1956-07-24
Anticipated expiration: 1973-07-24

Description

i i i July 24, 1956 E. v. BERGSTROM 2,756,192

REFORMING CYCLE GAS BY THERMOCOMPREISSOR Filed Dec. 3, 1952 4 Sheets-Shem l INVENTOR.

4 Sheets-Sheet 2 INVENTOR.

E V BERGSTROM REFORMING CYCLE GAS BY THERMOCOMPRESSOR July 24, 1956 Flled Dec 3, 1952 AEENT MNN V R V F! B? Q I mm E v BERGSTROM REFORMING CYCLE GAS BY THERMOCOMPRESSOR a Qwm R? RQ July 24, 1956 Flled Dec 3, 1952 July 24, 1956 E. v. BERGSTROM REFORMING cycua GAS BY THERMOCOMPRESSOR 4 Sheets-Sheet 4 Filed Dec. 3; 1952 INVENTOR. fQ/C M fifieasmoM my AGENT i i i i United States Patent REFORMINGCYCLE GAS BY THERMO- COMPRESSOR Eric V. Bergstrom, Short Hi lls, N. .l., 'assig nor to Socoriy Mobil Oil Company, Inc., a corporation of New York Application December 3,1952, Serial No. 323,817 '6 Claims. (Ci- 196 52 The present invention relates to hydrocarbon conversions and, more particularly, to hydrocarbon conversions in which the pressure of a gaseous comp'oiient of the reaction mixture is raised to a reaction pressure by a ther mocompressor driven by a vaporized liquid reactant.

The ejector is designed to handle large quantities of gases, liquids or even solids against a pressure less than that of the driving fluid and has been used for several decades for well pumps, bilge pumps, ash ejectors andffor lifting muddy, acid, alkaline and other fluids. In 1925 U. S. Patent No. 1,533,839 was granted to Eg'eland for a process and apparatus for cracking hydrocarbons in which the crude oil to be treated is drawn into thesystein by the vapors from the distillation of the oil. In this process the oil drawn into the system is not compressed. in 1928, U. S. Patent No. 1,659,948 was granted to Fox for a process of transferring gases and vapors in w hich an ejector driven by gas un der a pressure of about 1000 p. s. i. is used to introduce low pressure vapors and liquids into a vaporizing drum. It will be noted that the driving fluid in this process is a gas under a high pressure produced substantially entirely by a compressor. For about years the application of theeje ct ortothe problems of the industry was ignored until in 1940, U. S Patent No. 2,209,973 was granted to Houdry et al. for a process and apparatus for treatment of fluids which steam or other inert fluid is passed through an orifice having a Venturi throat for the purpose of atomizir'i g the liquid charge stock. It will be observed that the driving fluid in this application "is steam and the purpose is atomization of the liquid charge stock. In 1941 U. S. Pat} ent No. 2,248,118 was granted to Pew for a process of cracking mineral oil in which an ejector-simulatingniixer is used. The mixer havingan orifice and venue like throat is driven superheated steam nethe inert gas such as carbon dioxide, flue gas or dry hydrocarbon. It is to be noted that in this use of a device having a Venturi throat as a mixer the pressure impressed upon the driving fluid is derived from a compressor and that the vapors pass through an expansion valve thereby lowering the pressure thereon before entering the mixer. Finally, in 1951, U. S. Patent No. 2,570,607 was granted to Smith for an improvement in the vacuum distillation of reduced crude in which a conventional steam driven jet and condenser of conventional type is used to create the reduced pressure under which the distillation takes place. It now has been discovered that the reaction pressures desirable for hydrocarbon conversions can be created by means of an ejector or thermocompressor utilizing as a driving fluid a heated liquid reactant to compress and heat a gaseous constituent of the reaction mixture and thus dispense with a compressor driven by power extraneous to the reaction or reduce the power requirements for compressing the gaseous constituent of the reaction mixture to the reaction pressure. Accordingly, it is an object of the present inventionto heat a liquid reactant of a hydrocarbon conversion to a reaction temperature at a pressure greater than a reaction pressure and com- 2,756,192 Patented July 24, 1956 ICC press a gaseous or vaporous constituent of a reaction mix+ ture to be formed therewith to a reaction pressure. It is another object of the present invention to' heat a liquid reactant of a hydrocarbon conversion to a reaction tem perature at a pressure greater than a reaction pressure, to compress and to heat a gaseous constituent of a reac-- tion mixture to be formed therewith and to heat the mix ture of vapors of the liquid hydrocarbon reactant and gaseous or vaporous constituent of the mixture to a reaction temperature at the reaction pressure. Other objec'ts and advantages ofthe present invention will become apparent to those skilled in the art from the present description thereof taken in conjunction with the drawings in which Figure 1 is a schematic flow sheet of a hydrocarbon conversion process illustrating the application of the principles of the present invention to aconversion in which a moving bed of particle-form solid contact material is introduced into a reaction zone through a pressuring leg and removed therefrom through a depressuring leg in which the recycle gas which is the gaseous constituent of the reaction mixture is compressed to a reaction pressure in accordance with the principles of the present invention.

Figure 2 is a schematic flow sheet, of a hydrocarbon conversion process illustrating the application of the principles of thepresent invention to a conversion in which a moving bed of particle-form solid contact material is introduced into a reaction zone and withdrawn therefrom through pressure lock systems in which the minor amount of recycle gas used for pressuring and depressuring is compressed by a mechanical compressor while the major amount of recycle gas used in the reaction mixture is compressed by a thermocornpressor;

Figure 3 is a schematic flow sheet of a hydrocarbon conversion process employing a fixed bed of particle form contact material in which the gaseous constituent of the reaction mixture iscompressed into a reaction pres;- sure by a thermocompress'or driven by the heated liquid reactant of the aforesaid reactionmixture; and

Figure is a vertical section of a multi-stage thermocornpressor. I

While the principlesof the present invention are applicable to any hydrocarbon conversion in which a liquid reactant is heated at elevated pressures greaterthan the reaction pressure of the order of about to about 500 p. s. i. to a reaction temperature and a constituent of the reaction mixture is a vaporo'us or gaseous material available at pressures below the reaction pressure,fthe appli cation of the principles of the present invention to the reforming of hydrocarbons has been chosen for the purpose of illustration. i r I I,

At the outset, it is to be understood that the reiriwirif orming includes thosemol'ecular changes individually designated as hydrogenation, dehydrogenation, isQmer'iZation, and dehydrocyclization whether the hydrocarbon uh"- dergo'es only one of the aforesaid molecular changes.

Reforming is achieved either in the absence or presenceof a catalyst. When achieved in the absence "of a catalyst it is known asthermal reforming, and when carried out inthe presence of a catalyst it is known as catalytic reforming.

There are many catalysts known variouslyas isomerization catalysts, dehydrogenation catalysts, hydrog'na tion catalysts 'or simply as reforming catalysts. Presently, it is ipre fe'rrred to employ a chromia-alumin'a reforming catalyst comprising at least 70 mol per cent alumina and about 18 to about 30 mol per cent chro'rnia.

The catalytic reforming reaction is carried out at ternpe'r'atures of about 850 to about 1080 F. preferably at about 960 toabout 1060 F. and at pressures of about 0 to about 600 p. s. i. a. In general, it is preferred to treat the hydrocarbon or hydrocarbons to be reformed in the presence of a gaseous heat carrier which is recycled andcontains up to about 85- per cent hydrogen, balance C1 to Ca hydrocarbons, including gases devoid of or subistantially devoid of hydrogen although it is preferred to employ gases comprising about 25 to about 85 per cent hydrogen, balance C1 to C5 hydrocarbons'and particularly gases comprising about 35 to about 60 per cent hydrogen, balance C1 to C6 hydrocarbons.

The reaction mixture for catalytic reforming comprises a hydrocarbon reactant such as a hydrocarbon, or a mixture of hydrocarbons at least some of which are capable of undergoing any or all of the molecular changes, isomerization, hydrogenation, dehydrogenation, and dehydrocyclization or dehydroaromatization, and a gaseous heat carrier preferably a hydrogen-containing gas comprising about 25 to about 85 per cent hydrogen and the balance C1 to Cs hydrocarbons and preferably comprising about 35 to about 60 per cent hydrogen and the balance C1 to C6 hydrocarbons. The reaction mixture or charge mixture comprises about 1 to about 15 preferably about 4 to about 10 mols of gas per mole of hydrocarbon reactant or about 1 to about 8, preferably about 2 to about 5 mols of hydrogen per mole of hydrocarbon reactant. When the hydrocarbon reactant is a mixture of hydrocarbons, the average molecular weight is determined in the usual manner from the A. S. T. M. distillation curve.

The space velocity, i. e volumes of liquid reactant, per hour, per volume of catalyst per hour is about 0.1 to about 6.0 and preferably about 0.5 to about 2.0.

, During the conversion, the catalyst becomes deactivated .by the deposition of a carbonaceouscontaminant usually and hereinafter, designated as coke. The catalyst isreactivated by burning the coke in a stream of combustionsupporting gas such as air at temperatures of about 600 to about 1400 F. and preferably about 700 to about 1100" F. at pressures of about to about 150 p. s. i. a. and preferably at about 15 to about 35p. s. i. a.

' In general, the present invention provides heating a hydrocarbon reactant as defined hereinbefore under pressure of about 500 to about 2500 p. s. i. and preferably about 750m about 1250 p. s. i. to a temperature such that ata reaction pressure of about 0 to about 600 preferably about 100 to about 300 p. s. i. the heated hydrocarbon reactant vapors then flow as the driving fluid successively through one or more single or multiple stage thermo-compressors to heat and pressurize the gaseous constituent of the reaction mixture such as a recycle gas described hereinbefore to a reaction pressure. The vaporous hydrocarbon reactant and the gaseous constituent of the reaction mixture then flow at a reaction pressure into a reaction zone, When the charge mixture, i. e., the mixture of hydrocarbon reactant and gaseous constituent of the reaction mixture although at a reaction pressure is not at a reactiontemperature, the charge mixtureflows from the thermo-compressor or compressors to a furnace in which the charge mixture is heated to a reaction temperature. Alternatively, when it is necessary to heat the charge mixture to a reaction temperature and more than one thermocompressor is used through which the charge mixture passes successively, the charge mixture can be heated to a reaction temperature intermediate any two thermocompressors. The heated charge mixture at a reaction. temperature and pressure flows into a reactor wherein it is subjected to reaction conditions of temperature, pressure and residence time and the vaporous contents of the reactor removed to be subjected to separation into reaction products, unreacted hydrocar bon reactant and gases Thereafter, the reaction products are subjected to such finishing treatment as is necessary or desirable and the unreacted hydrocarbon and gases recycled to the reaction zone in accordance with conventional practice.

The hydrocarbon conversion chosen for the purpose of illustrating the principles of the present invention is that of reforming. Figure 1 is a schematic flow sheet illustrative of the application of the principles of the present invention to a method of reforming in which a particle-form solid reforming catalyst flows through a reaction zone at a reaction pressure of about 0 to about 600 p. s. i. and preferably about 100 to about 300 p. s. i and at a reaction temperature of about 850 to about 1080 F. preferably about 960 to about 1060 F. The deactivated catalyst flows from the reaction zone or reactor to a kiln or regenerator wherein the coke deposited on the catalyst during passage through the reaction zone is burned off at a temperature of about 600 to about 1300 F., preferably about 800 to about 1100 F. at a pressure of about 0 to about 600 p. s. i. and preferably about 0 to about p. s. i. in a stream of combustion-supporting gas such as air.

In detail the illustrative operation is as follows: Active catalyst in reactor feed bin 11 flows into pressuring leg 12. Pressuring leg 12 is designed to have a substantially continuously decreasing cross-section dependent upon the pressure difierential at any two points in the length of the leg as expressed by the equation,

1 ray? Af P where A1 and A2 are cross-sectional areas of the leg at selected levels 1 and 2 and P1 and P2 are the absolute gas pressures existing at levels 1 and 2 respectively, said P1 being greater than P2, and n is a constant having a value of minus about 0.15 to minus about 1 as more fully described in co-pending application for United States Letters Patent, Serial No. 108,828 filed in the names of Russell Lee and Robert H. Drew on August 5, 1949, now abandoned, and co-pending application for United States Patent, Serial No. 329,882, filed in the names of Robert H. Drew and Russell Lee on January 6, 1953. p

The active catalyst flows downwardly through feed leg 12.as a substantially compact column into reactor 13. The particle-form solid reforming catalyst flows as a substantially compact column downwardly through reactor 13 and flows out of reactor 13 through conduit 14 under control of catalyst flow control 15 which can be of any suitable type such as a throttle valve into seal chamber 16.. Sealing gas such as steam, flue gas, or preferably hydrocarbon recycle gas drawn from a source not shown through pipe 79 under control of valve 81 at a pressure at least 0.5 p. s. i. greater than the pressure in reactor 13 is introduced into sealing chamber 16. The deactivated catalyst flows from seal chamber 16 through depressuring leg 17 into gas disengagor 18.

Depressuring leg 17 is a conduit the cross-sectional area of which increases with decrease in pressure in accordance with the equation.

1 agaym wherein A1 and A2 are areas at selected points 1 and 2 in depressuring leg 17 and P1 and P2 are absolute gas pressures at points 1 and 2 respectively and n in a constant varying from minus about 0.15 to minus about 1.0 as more fully described in the co-pending application for United States Letters Patent, Serial No. 329,882, filed January 6, 1953, in the names of Robert H. Drew and Russell Lee.

In the gas disengagor 18 the entrained gas escapes through pipe under control of valve 82. The deactivated, depressurized, degassed particle-form solid reforming catalyst flows from gas disengagor 18 through catalyst fiow control means 19 which can be of any suitable type such as a throttle valve into conduit 20 and thence along chute 21 to any suitable catalyst transfer means 22 whereby the deactivated catalyst can be transferred to a kiln or regenerator 26. Catalyst transfer means 22 can be a gas lift and the like and elevator, etc.

The catalyst transfer means 22 delivers the deactivated 44. ,4 w V; U...

catalyst to chute 23 along which the deactivated catalyst flows to regenerator feed bin 24., The deactivated cata lyst flows from regenerator feed hopper 24 through conduit 25 to kiln or regenerator 26 which can be of any suitable type wherein the coke laid down on the catalyst during reforming is burned off in a combustion-supporting gas such as air. The temperature of the catalyst is kept be low catalyst damaging temperatures by means of cooling coils represented by coil 30 through which flows heat exchange medium, such as steam, molten salt, low melting allows, etc. As illustrated, steam from steam drum 33 flows through pipe 31, coil 30 and back through pipe 32 to. steam drum 33.

The de-coked or reactivated catalyst flows fromregenerator or kiln 26 through conduit 27 to chute 28 and thence to a catalyst transfer means 29 of any suitable type whereby the reactivated catalyst can be transferred toreactorfeed bin 11. Catalyst transfer means 29 can be gas-lift or the like, any elevator, etc.

The reactivated catalyst is transferred from chute 28 by means of catalyst transfer means 29 to chute 83 and thence to reactor feed bin 11 ready to begin another cycle through the reaction zone.

The hydrocarbon reactant capable of undergoing any or all of the molecular changes, isomerization, dehydrogenation, hydrogenation, and dehydrocyclization or. aromatization, for example-a naphtha flows fro-m a source not shown through line 50 into absorber 51 where preferably in counter-current flow, the naphtha contacts a portion of the gas from gas-liquid separator 43 flowing therefrom through pipes 63 and 64. The naphtha flows from absorber 51 through line 52 to heat exchanger 40 where it is in heat exchange with efiluent from reactor 13. The naphtha flows from heat exchanger 40'through line 52 to pump 53 wherein the pressure is raised to about 500 to about 2500 p. s. i. and preferably about 750 to about 1250 p. s. i. controlled by valve 56 at the aft end of furnace 55.

It is well known to those skilled in the art that when heating hydrocarbons to reaction temperatures appreciably above the boiling range of the hydrocarbons that greater thermal efliciency is achieved with less cracking the higher the pressure under which the vaporizable hydrocarbons are heated.

' The pressurized naphtha at a pressure of about 500 to about 2500 p. s. i. and preferably about 750'to about 1250 p. s. i. flows from pump 53 through line 54 to furnace 55 where in coil 59 the temperature of the naphtha is raised to about 700m about 1000 F. and preferably about 700 to about 850 F. The heated naphtha then flows through pressure control valve 56 to one or more thermocornpressors 57 at a temperature of about 700 to about 1000 F. preferably about 700 to about 850 F. and a pressure of about 500 to about 2500 p. s. i. preferably about 750 to about 1250 p. s. i. The heated naphtha flows through the thermocompressor(s) 57 as the driving fluid inducting and compressing the gaseous constituent of the reaction mixture, in the illustration, recycle gas flowing from gas-liquid separator 43 under control of valve 65 through

pipes

63, 62 and heat exchanger 38 to thermocompressor 57.

The charge mixture comprising naphtha and recycle gas in the mol ratio of about 1 to about mol, preferably about 4 to 10 mols recycle gas or about 1 to about 8 preferably about 2 to about 5 mols hydrogen per mol naphtha flows from thermocompr'essor(s) 57 at a pressure of about 25 to about 600 p. s. i. preferably at about 100 to about 300 p. s. i. When the temperature of the charge mixture is at least about 850 F. preferably about 960 F. the charge mixture flows from thermocompressor(s) 57 through line 5-8 and by-passes coil 60 of furnace 55 flowing through line 84 under control of valve 85 to line 61.

When the temperature of the charge mixture flowing from thermocompressor(s) 57 is less than about 850 F.

6 preferably about 960 F., all or a part of the charge mixture flows through coil 60 of furnace 55 and the balance through line 84 so that the charge mixture flowing through line 61 is at a temperature of about 850 F. to about 1080" F. preferably about 960 to about 1060 F.

The heated charge mixture at a reaction pressure and temperature flows through line 61 to distributor 66 in reactor 13. Distributor 66 is of any suitable type whereby the charge mixture can be distributed across the cross-section of reactor 13. Distributor 66 can be located at the vertical mid-point of reactor 13 to provide two reforming zones having catalyst beds of equal depth or the distributor can be located to provide catalyst beds of different depths as disclosed in co-pending application for United States Letters Patent, Serial Nos. 285,481, now Patent No. 2,738,308, and 285,482, now Patent No. 2,742,404, both filed May l, 1952, in the name of Kenneth M. Elli- Ott.

The charge mixture flows partly upward counter-current to the downwardly flowing substantially compact column of particle-form reforming catalyst and partly downward concurrent with the downwardly flowing substantially compact column of catalyst. The distribution of charge mixture between the upper reforming zone and the lower reforming zone is regulated by the setting of valve 69 in reactor effluent line 67 to pass about 15 to about 85 per cent of the total entering volume of charge mixture and valve 70 in eflluent line 68 being set to pass the balance of the charge mixture.

The reformate from the upper reforming zone and the reformate from the lower reforming zone being of substantially the same octane rating are combined in line 86 and the combined efliuent flows through heat exchanger 38 where it is in heat exchange with the recycle gas, thence to heat exchanger 39 where the effluent is in heat exchange with steam flowing from steam drum 33 through pipes 34- and 36 and returned to drum 33 through pipe 37. The eflluent flows from heat exchanger 39 to heat exchanger 40 where it is in heat exchange with hydrocarbon reactant to be reformed. The efliuent flows from heat exchanger 40 to condenser 41 where most of the hydrocarbons are condensed. The condensed and uncondensed effluent flows from condenser 41 through line 42 to liquid gas separator 43.

In liquid gas separator 43 the uncondensed eflluent forms the upper vaporous phase and flows therefrom through pipe 63 to pipes 62 and 64 and thence as recycle to thermocompressor(s) 57 under control of valve 65 or to absorber 51. The condensed eflluent form the lower liquid phase in liquid-gas separator 43 from which the condensed effluent flows through line 44 to depropanizer 45.

In depronanizer 45 the propane and lighter of the condensed effiuent is taken as overhead'through pipe 71 to pipe 72 and thence to refinery fuel reservoir 73-. The bottoms fro-m depropanizer 41 flow through line 46 to primary re-run tower 47 where a high octane rating gasoline is taken as overhead through line 74 to-storage 76.

The bottoms from primary re-run tower 47 flow through line 48 to secondary re-run tower 49 where a high octane gasoline is taken overhead through line 75 to storage 76. The bottoms from secondary re-run tower 49 flow through line 77 to storage78.

In Figure 2 a method of reforming a hydrocarbon reactant such as naphtha in the presence of a moving bed of particle-form solid reforming catalyst is illustrated in a schematic manner. The primary difference betweenv the flow sheet Figure 1 and Figure 2 is the use of pressure locks in the latter to pressurize the catalyst and depressurize the catalyst instead of pressuring and depressuring legs as shown in Figure 1. Consequently, while in the method illustrated in Figure 1 substantially all of the recycle used in the process is compressed in the thermocompressor(s) in the method illustrated in Figure 2 a minor portion say about 1 to about 15 per cent of the recycle gas used to pressurize and depressurize the catalyst is compressed with a mechanical pump or compressor.

Active catalyst in reactor feed bin 111 is introduced into reactor 117 through areactor-sealing and catalyst transfer means of any suitable type such as the pressure lock comprising gas-

tight valves

112 and 114 and intermediate pressuring chamber 113. The pressuring lock operates as follows in a cyclic manner: With gas-tight valve 112 open and gas-tight valve 114 closed, particleform solid reforming catalyst flows into pressuring chamber 113 to fill said chamber to a pre-determined level. Gas-tight valve112 is closed and chamber 113 and the contents thereof purged with an inert and/or non-flammable gas such as flue gas flowing from a source not shown through pipe 187 under control of valve 188 with

valves

180 and 192 closed. The purge is vented through

pipes

193 and 194 with valve 196 open. After purging pressuring gas such as recycle gas drawn from pipe 177 by compressor or pump 203 flows under pressure about 0.5 p. s. i. greater than reactor pressure through pipe 179 under control of valve 180 into chamber 113 until the pressure in chamber 113 is at least 0.5 p. s. i. greater than the pressure in reactor 117. Gas-tight valve 114 is opened andthe catalyst flows into surge chamber 115. When chamber 113 is empty of catalyst gas-tight valve 114 is closed and chamber 113 purged with an inert and/or non-flammable gas such as flue gas in the manner described hereinbefore. This completes the cycle.

The pressurized catalyst in surge .chamber 115 flows into reactor 117 through conduit 116. The particleform solid reforming catalyst 'flows dovmwardly through reactor 117 as a substantially compact column of particleform solid reforming catalyst.

The deactivated catalyst contaminated with coke flows from reactor 117 through catalyst flow control means 118 of any suitable type such as a throttle valve into surge bin 119. The catalyst is removed :therefrom through a reactor-sealing and catalyst transfer means of any suitable type whereby particle-form solid contact material can be :transferred from a zone of given pressure to a zone of lower pressure. As illustrated, the reactor sealing and catalyst transfer means is a pressure lock comprising gas-

tight valves

120 and 122 and intermediate depressuring chamber 121. The depressuring lock operates in a cyclic manner asfollows: With

gastight valves

120 and 122 closed pressuring gas such as recycle gas drawn from pipe 177 by pump or compressor 203 flows through pipes 179 and 181 under control of valve 189 into pipe 190 and thence into depressuring chamber 121 with

valves

192, 201 and 202 closed. When the pressure in depressuring chamber 121 is approximately that of reactor 117 and surge bin 119 valve 189 is closed and gas-tight valve 120 is opened. Catalyst flows from surge bin 119 through valve 120 into depressuring chamber 121 until chamber 121 is filled to a predetermined level. Gas-tight valve 120 is closed and the gaseous contents of chamber 121 is vented through

pipes

198 and 200 under control of valve 202. When the pressure in chamber 121 is that of the kiln or regenerator 129, valve 202 is closed and chamber 121 and its contents purged with an inert and/or non-flammable gas such as flue gas flowing from a source not shown through pipe 191 under control of valve 192 and vented through

pipes

198 and 199 under control of valve 201. chamber 121 and its contents have been purged valve 192 is closed and gas-tight valve 122 is opened. The depressurized deactivated catalyst in chamber 121 flows into surge chamber 123 through gas-tight valve 122. When depressuring chamber 121 is empty of catalyst, gas-tight valve 122 is closed completing the cycle.

The depressurized, deactivated catalyst flows from surge bin .123 through conduit 124 to chute 125 to catalyst transfer means whereby the catalyst is transferred to a kiln or regenerator of any suitable type such When , 8 as that illustrated in Figure 1. Suitable catalyst transfer means are gas-lift and the like, elevators, etc.

The hydrocarbon reactant capable of undergoing at least one of the molecular changes, isomerization, hydrogenation, dehydrogenation and dehydrocyclization or aromatization drawn from a source not shown flows through line 166 to absorber 163 Where, in counter-current manner, the hydrocarbon reactant contacts the uncondensed portion of the reactor eifiuent flowing from liquid-gas separator 152 through

pipes

161 and 162. The hydrocarbon reactant flows from absorber 163 through line 167 to heat exchanger 148 where it is in heat exchange relation with the reactor efilueut and thence through line 167 to pump 168. Pump 168 raises the pressure on the liquid hydrocarbon reactant to about 500 to about 2500 p. s. i. and preferably to about 750 to about 1250 p. s. i. preparatory to heating the liquid hydrocarbon reactant. The liquid hydrocarbon reactant is pumped through line 169 to coil 171 in furnace 170 where the liquid hydrocarbon reactant is heated to a temperature of about 850 to about 1080 F., preferably about 960 to about 1060 F. The heated hydrocarbon reactant flows from coil 171 through back-pressure valve 172 to thermocompressor(s) 173 where recycle gas drawn from liquid-gas separator 152 through

pipes

161, 177 and 178 under control of valve 215 and heat exchanger 144 is inducted and compressed to form a charge mixture comprising the hydrocarbon reactant and recycle gas in the ratio of about 1 to about 15, preferably about 4 to about 10 mols recycle gas or about 1 to about 8, preferably about 2 to about 5 mols hydrogen per mol of hydrocarbon reactant.

The charge mixture flows from the thermocompressor(s) 173 at a pressure of about 0 to about 600 and preferably about to about 300 p. s. i. when the temperature of the charge mixture is at least about 850 and preferably at least about 960 F., i. e., the minimum reaction temperature the charge mixture by-passes coil 175 in furnace and flows through line 216 under control of valve 217 to line 176. When the temperature of the charge mixture in line 174 is below about 850, preferably about 960 F. at least a part thereof flows through coil 175 of furnace 170 where it is heated without substantial thermal reforming to a temperature such that the charge mixture in line 176 will have a temperature of about 850 to about 1080 F. and preferably about 960 to about 1060 F.

The heated charge mixture at a temperature of about 850 to about 1080 F, preferably about 960 to about 1060 F. and at a pressure of about 0 to about 600 p. s. i. and preferably about 100 to about 300 p. s. i. flows through line 176 to distributor 177.

In the event that gaseous constituent of the reaction mixture in addition to that combined with the hydrocarbon reactant is required such additional recycle gas, for example, can be drawn from pipe 177 by pump 203 and pumped through pipes 181 and 183 under control of valve 182 through furnace 184 and thence through pipe 185 into line 176. The additional gaseous constituent of the reaction mixture is heated in furnace 184 to a temperature such that when mixed with the charge mixture in line 176 the mixture has a reaction temperature, for example, of about 85 9 to about 1080 F. preferably about 960 to about 1060 F.

The charge mixture flows from distributor 216 partly upwardly and partly downwardly in accordance with the settings of throttle valves 141 and 142 in

reactor eflluent lines

139 and 140 respectively as described hereinbefore. That portion of the charge mixture which flows upwardly from distributor 216 flows counter-current to the downwardly flowing substantially compact column of particleform solid reforming catalyst. The effiuent from the upper portion of reactor 117 flows from the reactor through line 139 under control of valve 141 to line 143. That portion of the charge mixture which flows downwardly from distributor 216 flows concurrently with the downwardly flowing substantially compact column of particle-form solid reforming catalyst. The reformate thus produced together with the other gaseousv contents of the lower reforming zone flow from reactor 117 through line 140 under control of valve 142 to effluent line 143. v

v The effluent flows through heat exchanger 144. where it is in heat exchange relation with recycle, gas, thence through line 145 to heat exchanger 146 where it is in heat exchange relation with steam flowing from steam drum 134 through pipes 145 and 213 and returned to steam drum 134 through pipe 214. From heat exchanger 146, the reactor efliuent flows through line 147 to heat exchanger 148 Where it is in heat exchange relation with hydrocarbon reactant to be reformed and thence through line 149 to condenser 150.

The condensed and uncondensed effluent flows from condenser 150 through line 151 to liquid-gas separator 152 where the uncondensed efliuent is taken through line 161 to lines 162 where a portion flows to absorber 163 and the balance under control of valve 215 flows to pipe 177. After flowing through absorber 163 counter-current to hydrocarbon reactant to be reformed, the uncondensed effluent is stripped of light hydrocarbons. The stripped uncondensed eflluent flows from absorber 163 through line 164 to refinery fuel reservoir 165.

The condensed portion of the effluent flows from liquid- 'gas separator 152 through line 153 to depropanizer 154 Where a light fraction is taken overhead through pipe 204 to pipe 164 and the refinery fuel reservoir.

The bottoms from depropanizer 154 flow through line 155 to primary re-run tower 156 where high octane gasoline is taken as overhead through line 205 to storage 206 and the bottoms flow through line 157 to secondary rerun tower 158.

In secondary re-run tower 158 a high octane gasoline is taken overhead through line 207 to storage 206 and the bottoms flow through line 159 to storage 160.

The application of the principles of the present invention to a catalytic hydrocarbon conversion in which an in-place bed of catalyst is employed is illustrated by the schematic flow sheet, Figure 3.

Three

reactors

300, 400 and 500 provided with

catalyst inlets

301, 401 and 501 respectively and

catalyst outlets

302, 402 and 502 respectively are shown. Each reactor is provided with an inlet for

purge gas

304, 404 and 504 respectively under control of valves 306, 406 and 506 respectively. Each reactor is provided with an inlet for combustion-supporting gas such as

air

351, 451 and 551 respectively under control of

valves

352, 452 and 552 respectively and an outlet for purge gas and

flue gas pipes

311 and 307, 411 and 407 and 511 and 507 respectively'under control of valves 309, 409 and 509 respectively.

Each reactor is provided with an inlet for pressuring gas such as recycle gas such as

pipes

305, 405 and 505 respectively under control of

valves

307, 407 and 507 respectively.

The in situ catalyst bed reactors are operated in the usual manner. Thus, for example, reactor 300 is on stream while the catalyst in reactor 400 is being regenerated the reactor purged and pressured and the catalyst in reactor 500 is likewise being regenerated, the reactor purged and pressurized.

With reactor 300 ready to be put on stream a hydrocarbon reactant flows through line 312 to absorber 313 and flows downwardly in absorber 313 counter-current to upwardly flowing uncondensed efliuent from liquidgas separator 337 flowing through

pipes

322 and 353 under control of valve 354. Theuncondensed eflluent in passing through absorber 313 is stripped of light hydrocarbons and the stripped gas flows through pipe 349 to refinery fuel reservoir 350. The balance of the gas flows through pipe 322 to thermocompressor(s) 321.

The hydrocarbon reactant flows from absorber 313 through line 314 to pump 315. Pump 315 discharges into line 316 against the back-pressure of valve 319 which is set to ensure that the, hydrocarbon reactant is heated to a temperature of about 850 to about 1080 F., preferably about 960 to about 1060 F. at a pressure of about 0 to about 600 p. s. i. and preferably about 100 to about 300 p. s. i. As stated hereinbefore, greater thermal efliciency and less thermal cracking and reforming occurs when a hydrocarbon reactant such as naphtha is heated to a reaction temperature under pressures such as set forth hereinbefore.

The hydrocarbon reactant flows from pump 315 through line 316 to and through coil 318 of furnace 317 and is heated to about 700 to about 1000 F., preferably to about 700 to about 850 F. The heated oil flows from coil 318 under control of back-pressure valve 319 at a temperature of about 700 to about 1000 F. preferably about 700 to about 850 F. and at a pressure of about 500 to about 2500 p. s. i., preferably about 750 to about 1250 p. s. i.

The heated hydrocarbon reactant flows through one or more thermocompressors 321 whereby recycle gas is educted from pipe 322, compressed and heated to form a charge mixture comprising recycle gas and hydrocarbon reactant in the ratio of about 1 to about 15 mols, preferably about 4 to about 10 mols of recycle gas per mol of hydrocarbon reactant or about 1 to about 8 mols, preferably about 2 to about 5 mols hydrogen per mol of naphtha. The recycle gas containing 0 to 25% hydrogen or containing about 25 to about preferably about 35 to about 60% hydrogen and the balance C1 to Ca hydrocarbons.

The charge mixture flows from thermocompressor(s) 321 through line 355, at a pressure of about 0 to about 600 p. s. i., preferably about to about 300 p. s. i.

When the temperature of the charge mixture is at least about 850 and preferably at least about 960 F. the charge mixture flows from line 355 through line 356 to line 358. When the temperature of the charge mixture is less than about 850 to about 960 F. at least a portion flows through line 323 under control of valve 357 to and through coil 324 of furnace 317 wherein the charge mixture or a portion thereof is heated to a temperature such that the temperature of the charge mixture in pipe 358 is about 850 to about 1080" F., preferably about 960 to about 1060 F.

Since reactor 300 is ready to go on stream while reactor 400 is being purged and the catalyst in reactor 500 is being regenerated, the charge mixture in line 358 at a temperature of about 850 to about 1080 F., and at a pressure of about 100 to about 300 p. s. i. flowsthrough line 358 to line 326 with

valves

527 and 329 closed and valve 327 open to distributor 330 in reactor 300. Distributor 330 is of any suitable type whereby the charge mixture is distributed across the cross-section of reactor 300. The charge mixture vapors flow downwardly through the reactor in contact with the in situ bed of catalyst and leave reactor 300 through collector 331 of any suitable-type and line 332 under control of valve 333. With valves 533 and 433 closed the efiiuent from reactor 300 flows through line 334 to condenser 335; thence through line 336 to liquid-gas separator 337.

In liquid-gas separator 337, the uncondensed effluent flows upwardly through pipe 322 from which a portion usually equivalent to the net gas make is diverted through pipe 353 under control of valve 354 to absorber 313. After passing through absorber 313 counter-current to the downwardly flowing fresh hydrocarbon reactant, the uncondensed efl'luent stripped of light hydrocarbons flows through pipe 349 to fuel sphere 350.

The condensed effluent flows from liquid-gas separator 337 through line 338 to depropanizer 339. In depropanizer 339 an overhead is taken which flows through pipe- 345 to pipe 349 and thence to fuel sphere 350.

The bottoms from depropanizer 339 flow through line .340to primary re-run tower 341 where a gasoline fraction "of high octane rating is taken overhead through line 346 to storage 348.

The bottoms from primary re-run tower 341 flow through line 342 to secondary re-runtower 343 where a gasoline fraction of high octane rating is taken overhead throug'hline 347 to gasoline storage 343.

' The bottoms from secondary're-run tower 343 flow through line-344 to storage.

Reactor 400 after regeneration of the catalyst by combustion of; the coke laid down on the catalyst during the on-stream period is purged by passing an inert and/or nomfiammable gas such as 'flue gas drawn from a source not shown through pipe 451 under control of valve 452 through pipe 403 into reactor 400. The purge is vented through pipes 411 and 407 with valve 410 ciosed and valve 409 open. After purging valve 409 is closed. Valve 327 is closed thereby taking reactor 300 off stream and valve 329 is opened to permit the heated charge mixture in line 358. to flow through line 328 to distributor 430 of any suitable type. The charge mixture vapors flow downward through reactor 400 in contact with the in .situ bed of catalyst and thence through collector 431 of any suitable typeto line 432 under control of valve 433. From line 432 the efiluent from reactor 400 flows to line 334 and thence through condenser 335 and the after treatment as described hereinbefore.

Whilereactor 400 is being purged, the catalyst in reactor 500 is being regenerated. That is to say, a combustionsupporting gas such as air flows from a source not shown through pipe 504- under control of valve 506 (valve 552 closed) to pipe 503 and thence (valve 507 closed) to reactor 500. The combustion-supporting gas rises through reactor 500 and escapes therefrom through pipes 511 and 508 under control of valve 510 (valve 509 closed). When the catalyst isregenerated an inert and/ or non-flammable gas such as flue gas flows from a source not shown through pipes 551 and 503 (valve 552 open,

valves

506 and 507 closed) to reactor 500. The purge is vented through pipes 511 and 508. After purging reactor 500 is pressurized to a reaction pressure of about to about 600 p. s. i., preferably about 100 to about 300 p. s. i. with recycle gas flowing from a source not shown through pipes 505 and 503 under control of valve 507. Reactor 500 is then ready to be put on stream.

Reactor 500 is put on stream by closing

valves

327 and 329 and opening valve 527. The charge mixture at a temperature of about 850 to about lO80 F. and at a pressure of about 100 to about 300 p. s. i. in line 35; flows through line 526 to distributor 530 of any suitable type. The vapors of the charge mixture flow downwardly through reactor 500 in contact with the in situ bed of catalyst and leave reactor 500 through collector 531. The effluent flows through line 532 under control of valve 533 to line 334 and thence to condenser 335 and after treatment as described hereinbefore.

The catalyst in reactor 300, and in a similar manner the catalyst in

reactors

400 and 500 is purged after being taken off stream by passing an inert and/or non-flammable gas such as flue gas, drawn from a source not shown, through pipes 351 and 303 (451 and 403; 551 and 503 respectively) under control of valve 352 (452; 552) to reactor 300 (400; 500). The purge gas flows upwardly and is vented through pipes 311 and 307 (-411 and 407; 511 and 507) under control of valve 309 (409; 509). After purging the catalyst is regenerated by burning-01f the carb0- naceous contaminant (coke). in a stream of combustionsupporting gas such as air introduced from a source not shown through pipes 304 and 303 (404 and 403; 504 and 503) under control of valve 306 (406; 506). The com bustion-supporting gas flows upwardly and together with products of combustion escapes through pipes 311 and 307 (411 and 407; 511 and 507). After regeneration at temperatures of about 600 to about .1400" F., preferably about700 to a bout l100 R, the reactor is purged with an inert'and/or non-flammable gas such as flue gas as described hereinbeforc. After purging, reactor 3 00 (400; 500) is pressurized with a recycle gas to a react1on pressure by passing recycle gas under at least reaction pressure from a source not shown through pipes 305 and 303 (405 and 4015;505 and 503) under control of valve 30"] (407; 507) until the purge gas is displaced through pipes 311 and 308 (411 and 408; 511 and 503) under control of valve 310 (410; 510). Thereafter valve 310 (410; 510) is closed and the reactor pressurized to a reaction pressure of about 0 to about 600 p. s. i., preferably about 100 to about 300 p. s. i. When the reactor is at reaction pressure, valve 305 (405; 505) is closed and the reactor is ready to be put on stream by flowing heated charge mixture at a reaction pressure from line 358 to the reactor.

The specific design of the thermocompressor or compressors is not the subject of the present invention. Many types of thermocompressors which conform to the general design are available. Some are single-stage and others are multi-stage thermocompressors; either type can be used in the hydrocarbon conversions to which the principles of the present invention are applicable. For the sole purpose of illustration, a multi-stage thermocompressor is represented in Figure 4.

The thermocompressor comprises a shell 450 of cylindrical shape provided with a driving fluid inlet 451, an inlet for gas to be compressed and heated 452, one or more driving fluid nozzles 453, 454, 455, 456, 457 a throat 458 and discharge 459. The driving fiuid in this instance, the vapors of the hydrocarbon reactant at a temperature of about 700 to about 1000" F. preferably about 700 to about 850F. and at a pressure of about 500 to about 2500 p. s. i., preferably about 750 to about 1250 p. s. i., flows through line 460 and driving fluid inlet 451 successively through

nozzles

453, 454, 455, 456 and 457 inducting the gaseous constituent of the reaction mixture into the stream of vapors of hydrocarbon reactant from the annular space 461 through the entries 462, 463, 464 and 465. The charge mixture produced by induction of the gaseous constituent of the reaction mixture into the stream of vapors of hydrocarbon reactant is discharged through throat 458 and discharge 459 of the thermocompressor at a temperature of about 600 toabout 1000 F. and a pressure of about 0 to about 600 p. s. i. and preferably about 100 to about 300 p. s. i.

It is manifest that the foregoing description is of a method of hydrocarbon conversion at pressures in excess of atmospheric in which the hydrocarbon reactant is heated to at least the reaction temperature under a pressure in substantial excess of the reaction pressure, passed as the driving fluid through a thermocompressor or compressors into which the gaseous constituent of the reaction mixture is inducted, compressed and heated to form a charge mixture comprising the hydrocarbon rcactant and the gaseous constituent. That when the charge is discharged from the thermocompressor or compressors it is at an elevated reaction pressure and at an elevated temperature. That when the elevated temperature of the charge mixture is below the reaction temperature all or part thereof can be reheated to a temperature such thatthe charge mixture entering a reaction zone is at a reaction temperature and reaction pressure.

I claim:

1. .In the method for hydrocarbon conversion wherein a liquid hydrocarbon reactant is compressed to a conversion pressure, wherein a gaseous reaction component is compressed to said conversion pressure, wherein said compressed liquid hydrocarbon and said compressed gaseousreaction component are heated to a conversion temperature, wherein said heated compressed hydrocarbon reactant and said heated compressed gaseous reaction component are introduced into a conversion zone contacted with particle form solid catalytic material,

wherein vaporous conversion products are withdrawn from said conversion zone, wherein gaseous reaction component is separated from said withdrawn conversion products, and wherein said gaseous reaction component is compressed to a conversion pressure and heated to a conversion temperature and returned to said conversion zone, the improvement which comprises heating a liquid hydrocarbon reactant to said conversion temperature at an elevated pressure substantially in excess of said conversion pressure, passing said heated hydrocarbon reactant at said pressure in excess of said conversion pressure as a stream of driving fluid through at least one thermocompressor, entraining gaseous reaction component having a pressure less than said conversion pressure in said stream of heated hydrocarbon reactant driving fluid at said pressure in excess of said conversion pressure thereby compressing said gaseous reaction component to a conversion pressure and forming a conversion charge mixture having at least said conversion pressure, and contacting said particle form solid catalytic material in said conversion zone with said charge mixture at conversion temperature and pressure.

2. The improvement in the method of hydrocarbon conversion set forth and described in claim 1 wherein at least a part of the charge mixture is reheated at said conversion pressure to said conversion temperature.

3. In the method for reforming a hydrocarbon reactant in the presence of a particle form solid reforming catalyst which comprises compressing a liquid hydrocarbon reactant to a reforming pressure, compressing a recycle gas to a reforming pressure, heating said compressed hydrocarbon reactant and said compressed recycle gas to a reforming temperature, mixing said heated compressed hydrocarbon reactant and said heated compressed recycle gas to form a charge mixture at a reforming temperature and pressure, and contacting a particle form solid reforming catalyst with said heated compressed charge mixture at a reforming temperature and pressure, the improvement which comprises heating said liquid hydrocarbon reactant to a reforming temperature at an elevated pressure in substantial excess of the reforming pressure, passing said heated hydrocarbon reactant at said substantial excess pressure as a stream of driving fluid through at least one compressor, entraining recycle gas having a pressure less than said reforming pressure in said stream of hydrocarbon reactant driving fluid thereby compressing said recycle gas to a reforming pressure and forming a charge mixture having a reforming pressure, and contacting a particle form solid reforming catalyst with said charge mixture at a reforming temperature and pressure.

4. The improvement in the method of reforming a hydrocarbon reactant as set forth and described in claim 3 wherein the temperature of the recycle gas is less than said reforming temperature and said recycle gas is heated to said reforming temperature while being compressed to said reforming pressure.

5. The improvement in the method of reforming a hydrocarbon reactant as set forth and described in claim 3 wherein at least a portion of the charge mixture is heated to said reforming temperature after passage through said thermocompressor and before contact with said particle form reforming catalyst material.

6. The improvement in the method of reforming a hydrocarbon reactant as set forth and described in claim 3 wherein the liquid hydrocarbon reactant is heated to a temperature of about 700 to about 850 F. at a pressure of about 750 to 1250 p. s. i., and the charge mixture after passage from said thermocompressor has a pressure of about to about 300 p. s. i.

References Cited in the file of this patent UNITED STATES PATENTS 1,821,333 Tolman Sept. 1, 1931 2,376,833 Teter May 22, 1945 2,446,678 Voorhees Aug. 10, 1948 2,498,559 Laying et a1. Feb. 21, 1950

Claims

1. IN THE METHOD OF HYDROCARBON CONVERSION WHEREIN A LIQUID HYDROCARBON REACTANT IS COMPRESSED TO A CONVERSION PRESSURE, WHEREIN A GASEOUS REACTION COMPONENT IS COMPRESSED TO SAID CONVERSION PRESSURE, WHEREIN SAID COMPRESSED LIQUID HYDROCARBON AND SAID COMPRESSED GASEOUS REACTION COMPONENT ARE HEATED TO A CONVERSION TEMPERATURE, WHEREIN SAID HEATED COMPRESSED HYDROCARBON REACTANT AND SAID HEATED COMPRESSED GASEOUS REACTION COMPONENT ARE INTRODUCED INTO A CONVERSION ZONE AT SAID CONVERSION TEMPERATURE AND PRESSURE AND THEREIN CONTACTED WITH PARTICLE FORM SOLID CATALYST MATERIAL, WHEREIN VAPOROUS CONVERSION PRODUCTS ARE WITHDRAWN FROM SAID CONVERSION ZONE, WHEREIN GASEOUS REACTION COMPONENT IS SEPARATED FROM SAID WITHDRAWN CONVERSION PRODUCTS, AND WHEREIN SAID GASEOUS REACTION COMPONENT IS COMPRESSED TO A CONVERSION PRESSURE AND HEATED TO A CONVERSION TEMPERATURE AND RETURNED TO SAID CONVERSION ZONE, THE IMPROVEMENT WHICH COMPRISES HEATING A LIQUID HYDROCARBON REACTANT TO SAID CONVERSION TEMPERATURE AT AN ELEVATED PRESSURE SUBSTANTIALLY IN EXCESS OF SAID CONVERSION PRESSURE, PASSING SAID HEATED HYDROCARBON REACTANT AT SAID PRESSURE IN EXCESS OF SAID CONVERSION PRESSURE AS A STREAM OF DRIVING FLUID THROUGH AT LEAST ONE THERMOCOMPRESSOR, ENTRAINING GASEOUS REACTION COMPONENT HAVING A PRESSURE LESS THAN SAID CONVERSION PRESSURE IN SAID STREAM OF HEATED HYDROCARBON REACTANT DRIVING FLUID AT SAID PRESSURE IN EXCESS OF SAID CONVERSION PRESSURE THEREBY COMPRESSING SAID GASEOUS REACTION COMPONENT TO A CONVERSION PRESSURE AND FORMING A CONVERSION CHARGE MIXTURE HAVING AT LEAST SAID CONVERSION PRESSURE, AND CONTACTING SAID PARTICLE FORM SOLID CATALYTIC MATERIAL IN SAID CONVERSION ZONE WITH SAID CHARGE MIXTURE AT CONVERSION TEMPERATURE AND PRESSURE.