CA1067105A - Two-stage hydropyrolysis cracking process for producing ethylene - Google Patents
Two-stage hydropyrolysis cracking process for producing ethyleneInfo
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- CA1067105A CA1067105A CA228,935A CA228935A CA1067105A CA 1067105 A CA1067105 A CA 1067105A CA 228935 A CA228935 A CA 228935A CA 1067105 A CA1067105 A CA 1067105A
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- hydropyrolysis
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
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- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
Abstract of the Disclosure Ethylene along with methane may be produced by an integrated process involving a first stage hydro-pyrolysis of a hydrocarbon oil in the presence of hydrogen followed by cracking of the hydropyrolysis effluent, separating and recycling the hydrogen and ethane and recovering the methane and ethylene.
Description
:` :
10671Q5 ~
:
Thls inventlon relates to an lntegrated process -for produclng ethylene. More partlcularly, the lnventlon relates to an lntegrated two-stage hydropyrolysis-cracklng proce~s ~or produclng ethylene ~rom hlgher hydrocarbons.
Cracking of various petroleum fractlons to produce ethylene is well known ln the art. In general, rractlons ranglng ~rom ethane to heavy gas oll and even whole crude oil have been employed as feedstocks to these cracklng operatlons. The cracklng has been carrled out ln a varlety of equlpment lncludlng flred tubular heaters, pebble-bed heaters, rluldlzed-bed crackers, and the llke.
Many processlng schemeq have also been devlsed lncludlng recycle o~ various components to lncrease ethylene ylelds.
In accordance wlth thls lnventlon, there 18 provlded a novel lnteg~ated two-stage hydropyrolysls-cracklng process whereby hlgher hydrocarbons, lncludlng whole crude oll and hydrogenated coal llqulds, are pyro-lyzed to produce ethylene. The lntegrated process provldes not only for productlon Or ethylene but also methane whlch can be used ln synthetlc natural gas. Hydro-gen and all other hlgher organlcs may be recycled back into the process ~or eventual converslon to ethylene and methane although lt ls posslble to make further separatlons on the heavy organlc stream to recover aromatlcs whlch lnclude benzene, toluene, and xylenes. In the event aromatlcs are not separated ~rom the heavy organlc stream prior to recycle, lt is desirable to hydrogenate the stream to convert unsaturates to saturates.
The lntegrated process of the lnventlon 18 schematically lllustrated ln the accompanylng drawlng
10671Q5 ~
:
Thls inventlon relates to an lntegrated process -for produclng ethylene. More partlcularly, the lnventlon relates to an lntegrated two-stage hydropyrolysis-cracklng proce~s ~or produclng ethylene ~rom hlgher hydrocarbons.
Cracking of various petroleum fractlons to produce ethylene is well known ln the art. In general, rractlons ranglng ~rom ethane to heavy gas oll and even whole crude oil have been employed as feedstocks to these cracklng operatlons. The cracklng has been carrled out ln a varlety of equlpment lncludlng flred tubular heaters, pebble-bed heaters, rluldlzed-bed crackers, and the llke.
Many processlng schemeq have also been devlsed lncludlng recycle o~ various components to lncrease ethylene ylelds.
In accordance wlth thls lnventlon, there 18 provlded a novel lnteg~ated two-stage hydropyrolysls-cracklng process whereby hlgher hydrocarbons, lncludlng whole crude oll and hydrogenated coal llqulds, are pyro-lyzed to produce ethylene. The lntegrated process provldes not only for productlon Or ethylene but also methane whlch can be used ln synthetlc natural gas. Hydro-gen and all other hlgher organlcs may be recycled back into the process ~or eventual converslon to ethylene and methane although lt ls posslble to make further separatlons on the heavy organlc stream to recover aromatlcs whlch lnclude benzene, toluene, and xylenes. In the event aromatlcs are not separated ~rom the heavy organlc stream prior to recycle, lt is desirable to hydrogenate the stream to convert unsaturates to saturates.
The lntegrated process of the lnventlon 18 schematically lllustrated ln the accompanylng drawlng
- 2 -1(~67~05 together with certaln optional features deplcted by dotted line8.
The hydrocarbon oils suitable for use ln the process o~ thls lnventlon may be de~lned as those havlng a denslty Or less than about 0.99, preferably less than about 0.95, and a Conradson carbon content of less than about 20 welght percent, preferably less than about 2 welght percent. ~oth non-dlstillate and dlstlllate hydro-carbon 0118 are sultable such as respectlvely descrlbed ln U.S. RE 27599 and U.S. 3,363,024. For example, crude petroleum or other olls havlng slmllar denslty and vola-tlllty characterlstlcs may be used as well as 0118 derlved from coal such as hydrogenated coal oll. Dlstlllate 0118 boillng ln the range Or 30C to 360C may be used. Slml-larly, coal tar dlstlllates contalnlng unsubstltuted or hydroxy-substltuted hydrocarbons can be used. Gases con-sistlng prlmarlly of butane and propane are satlsfactory feedstocks. All Or the above are lntended to be lncluded wlthln the expresslon "hydrocarbon 0118."
The hydrocarbon 0118 as descrlbed above are lntroduced to a ~lrst-stage hydropyrolysls zone along wlth hydrogen. In the hydropyrolysls zone, the hydrocarbon olls are pyrolytlcally cracked ln the presence of hydrogen to lower hydrocarbons. From an equlpment standpoint, a suitable reactor for conductlng the hydropyrolysls 18 descrlbed ln U.S. 3,363,024, supra. Another sultable devlce ls a conventlonal tubular furnace used in the uRual cracklng operatlons.
The hydropyrolysls ls conducted with a mol ratio of hydrogen to hydrocarbon 0118 of at least 1/l, - 1~)671~)5 preferably at least 3/l. The more hydrogen present the less the tendency to form carbon in the zone, other rele-vant factors remainlng constant such as temperature, pressure, etc. Another factor to be consldered ln deter-mlnlng the amount of hydrogen to employ ln a partlcular operatlon ls that lncreased hydrogen favors ethane pro-duction over ethylene. Thls factor has slgnlficance ln connectlon with the second-stage cracking ln that ethane ls dehydrogenated to ethylene ln that stage. A futher con-slderatlon 18 wlth the amount of excess hydrogen that must be processed an~ recycled through the lntegrated process.
All factors con~ldered, lt ls preferable to operate with hydrogen to hydrocarbon oll mol ratlos in the range of about 3/1 to 30~1.
The hydrogen for the hydropyrolysls stage ls provlded by recycllng the hydrogen separated ln the sub-sequent separatlon stage to be descrlbed more~fully hereln-after, and addltlonally from any sultable outslde source.
The hydrogen and hydrocarbon oll feed may be separately lntroduced to the hydropyrolysls stage or they may be combined and lntroduced as a mixture. The hydro-carbon may be lntroduced through an atomlzing nozzle uslng hydrogen as the atomlzlng gas. Preferably, the hydrocarbon oll is preheated to a temperature approachlng the operating temperature of the hydropyrolysls zone; e.g., 300C to as hlgh as 550C.
The hydropyrolysis ls carried out at temperatures in the range of 600C to 900C, preferably 700C to 850C.
Higher temperatures favor ethylene over ethane. Pressures la67l0s of at least 5 atmospheres gauge are employed, usually in the range o~ 5 to lO0 atmospheres gauge and preferably in the range o~ 15 to 30 atmospheres gauge. Lower pressures ~avor ethylene to ethane. Resldence tlmes ln the range of 0.1 second to 60 seconds, pre~erably 0.5 to 20 seconds, are employed. Shorter residence times ~avor ethylene over ethane.
Carbon deposltion arising ~rom side reactions in the hydropyrolysis zone can be inhibited by provlding a small concentration of æulfur compounds ln the hydrocarbon oil ~eed ir not already present; e.g., lO ppm. This is well known ln the art and ls generally rererred to as pas-si~lcatlon. Usually the addltlon o~ sulfur compounds 18 done on a contlnuous basls.
An alternatlve to the use o~ sul~ur compounds 18 water or steam although for a glven degree Or e~ec-tiveness in inhlbitlng carbonlzation, greater quantlties o~ water are required compared to sulfur compounds.
Usually, up to about 3 mol of water per mol Or hydrocarbon oll wlll be e~fectlve although greater quantltles can be employed. Water not only lnhlblts carbonlzatlon but lt has also been found that water af~ect~ hydropyrolysis by tending to favor ethylene over ethane.
The efrluent from the first--stage hydropyrolysls zone i8 then lntroduced to the second-stage cracking zone.
In the second-stage cracking zone, the ef~luent is sub-~ected to low pressure cracking. Temperatures ln the lQ6~1~S
range o~ 750 to 900C, pre~erably 800-850C, are employed.
Pressures usually not above about 2 atmosphere~ gauge, and preferably not above 1 atmosphere gauge, are used.
The resldence tlme may be ln the range o~ about 0.01 second to 10 seconds wlth 0.1 second to 1 second being pre~erred.
Slnce the condltlons in the second-stage cracklng zone are also ldeal ~or dehydrogenatlng ethane to ethylene, ethane ~rom the separatlon zone 18 recycled to the second-stage cracklng zone. Thus, the second-stage zone not only serves to crack higher hydrocarbons ln the e~luent ~rom the ~irst stage hydropyrolysis zone but also serves to dehydrogenate ethane whlch 18 produced both in the ~lrst and second stages as well as that recycled.
The efrluent product mlxture ~rom the second stage cracklng zone ls then processed for recovery of methane and ethylene ln the separatlon zone. Conventional technlques ~or separatlng hydrogen, methane, ethylene, ethane and hi~her hydrocarbons may be employed. A con-venlent separation and recovery system lnvolves rapldly coollng or quenchlng the product mlxture lmmedlately on exltlng from the second-stage cracklng zone and then processlng the cooled mlxture through a serles of low-temperature ~ractional dlstlllatlon columns as are known ln the art. Hydrogen ls ~lrst separated and recycled to the flrst-stage hydropyrolysls zone as earller dlscussed.
Methane ls then separated and recovered and may be con-veniently utillzed as a synthetic natural gas component.
Ethylene ls next to be separated and may be sent to 3o storage or transport as an ltem of commerce. Ethane ls ~ 6 --1~67105 next separated and recycled to the second-stage cracking zone as earller described. The remalnlng hlgher hydro-carbons are then hydro~enated ln a conventlonal manner to remove any unsaturatlon and recycled to the flrst-stage hydropyrolysls zone to again be processed and con- `
verted to lower hydrocarbons and eventually to ethylene and methane.
Whlle the above technlque for separation ls essentlally a selectlve step-wlse dlstlllation, it should also be mentloned that the reverse may also be employed, that ls, a ~elec~lve step-wise condensatlon.
Slnce the hlgher hydrocarbons wlll contaln ~`
varylng amounts Or aromatics, principally benzene, toluene, and xylenes, a ~urther separatlon step may be performed prlor to hydrogenatlon and recycle. Such separatlon may be accompllshed in any known manner to separate essentlally -all aromatics or only those components deQired. If essen-tlally all aromatlcs are separated, the remainlng higher hydrocarbon stream may be recycled as is to the first-stage hydropyrolJsis zone without hydrogenatlon. It ls preferred, however, to hydrogenate the higher hydrocarbon stream prior to recycle even though the aromatics or some of the aromatics have been removed.
The followlng examples wlll æerve to further lllustrate the lnventlon.
Example l A mlxture of 2.3 llquld vol/min kerosene (bolllng polnt range of 190C to 270C and a specifJc gravlty of 0.82), 2.65 liquid vol/mln water and 161 gas vol/min hydrogen (mol ratio of H2 to hydrocarbon ls about lQ671~5 18.0) are lntroduced to the ~irst-stage hydropyrolysls zone of a type descrlbed in U.S. 3,363~024. Recycle hydrogen and recycle hlgher hydrocarbon inlets are also provided. The hydropyrolysls ls conducted at temperatures ranging from 750-800C, a pressure of 20.4 atmospheres gauge and a residence tlme of 7-lO seconds.
The effluent from the first-stage hydropyrolysis zone is then depressured lnto the second-stage cracking zone of a tubular furnace type. An ethane recycle lnlet ls also provlded to this zone. The second-stage cracking iB carried out at temperatures of 850-900C, pressures of 0.7-1.7 atmospheres gauge and a residence tlme ranglng from 0.1-0.5 second.
The product mlxture from the second-stage hydro-pyrolysls zone ls rapldly cooled or quenched and conducted lnto a ~erles Or fractlonal dlstillatlon columns. Hydro-gen is separated and recycled to the flrst-stage hydro-pyrolysis zone. Methane i8 separated and sent to storage.
Ethylene 18 separated and sent to storage. Ethane is separated and recycled to the second-stage cracking zone.
The remainlng hlgher hydrocarbon stream is hydrogenated and recycled to the flrst-stage hydropyrolysls zone.
Example 2 A llght naphtha (BP 85-150C) at a rate of 0.034 ml/min and hydrogen at a rate Or 100 cc/mln (mol ratio of hydrogen to hydrocarbon o~ about 16.2) were lntroduced to a hydropyrolysis zone formed by a 3/8-lnch stalnless steel tubular reactor one foot ln length Or which a volume of about 16 cc in the central area constituted the hot zone. The hydropyrolysis was carried out at a ; - 8 -~,Q67105 - `
temperature Or 750C (hot polnt), a pressure of 6.8 atmos-pheres gauge and an average resldence tlme o~ 2.5 sec.
The efrluent from the hydropyrolysis zone was analyzed by GLC as 12.4 weight percent H2, 36.3 welght percent methane, 1.1 weight percent ethylene, 41.4 weight : .
percent ethane, and 9.0 welght percent higher hydrocarbons.
The e~luent rrom the hydropyrolysls is then introduced to second-stage cracklng operated under atmos- -pherlc pressure and 800-850C. Calculatlons based on thermodynamlc equlllbrlum at 850C lndlcate a product ~
contalnlng a hydrocarbon distrlbution as rOllOws: :
41 welght percent methane, 23.4 welght percent ethylene, 26.6 weight percent ethane, 4.9 welght percent benzene, and 4.1 welght percent higher hydrocarbons.
~he methane, ethylene, and benzene are recovered, ~.
the hydrogen and hlgher hydrocarbons are re¢ycled to the hydropyrolysls zone and the ethane ls recycled to the second-stage cracklng zone.
: Thus, havlng descrlbed the lnventlon ln detall, lt wlll be understood by those s~llled in the art that certaln varlatlons and modlrlcatlons may be made wlthout departlng rrom the splrit and scope Or the lnventlon as descrlbed hereln and derlned ln the appended claims.
. ......................... .
The hydrocarbon oils suitable for use ln the process o~ thls lnventlon may be de~lned as those havlng a denslty Or less than about 0.99, preferably less than about 0.95, and a Conradson carbon content of less than about 20 welght percent, preferably less than about 2 welght percent. ~oth non-dlstillate and dlstlllate hydro-carbon 0118 are sultable such as respectlvely descrlbed ln U.S. RE 27599 and U.S. 3,363,024. For example, crude petroleum or other olls havlng slmllar denslty and vola-tlllty characterlstlcs may be used as well as 0118 derlved from coal such as hydrogenated coal oll. Dlstlllate 0118 boillng ln the range Or 30C to 360C may be used. Slml-larly, coal tar dlstlllates contalnlng unsubstltuted or hydroxy-substltuted hydrocarbons can be used. Gases con-sistlng prlmarlly of butane and propane are satlsfactory feedstocks. All Or the above are lntended to be lncluded wlthln the expresslon "hydrocarbon 0118."
The hydrocarbon 0118 as descrlbed above are lntroduced to a ~lrst-stage hydropyrolysls zone along wlth hydrogen. In the hydropyrolysls zone, the hydrocarbon olls are pyrolytlcally cracked ln the presence of hydrogen to lower hydrocarbons. From an equlpment standpoint, a suitable reactor for conductlng the hydropyrolysls 18 descrlbed ln U.S. 3,363,024, supra. Another sultable devlce ls a conventlonal tubular furnace used in the uRual cracklng operatlons.
The hydropyrolysls ls conducted with a mol ratio of hydrogen to hydrocarbon 0118 of at least 1/l, - 1~)671~)5 preferably at least 3/l. The more hydrogen present the less the tendency to form carbon in the zone, other rele-vant factors remainlng constant such as temperature, pressure, etc. Another factor to be consldered ln deter-mlnlng the amount of hydrogen to employ ln a partlcular operatlon ls that lncreased hydrogen favors ethane pro-duction over ethylene. Thls factor has slgnlficance ln connectlon with the second-stage cracking ln that ethane ls dehydrogenated to ethylene ln that stage. A futher con-slderatlon 18 wlth the amount of excess hydrogen that must be processed an~ recycled through the lntegrated process.
All factors con~ldered, lt ls preferable to operate with hydrogen to hydrocarbon oll mol ratlos in the range of about 3/1 to 30~1.
The hydrogen for the hydropyrolysls stage ls provlded by recycllng the hydrogen separated ln the sub-sequent separatlon stage to be descrlbed more~fully hereln-after, and addltlonally from any sultable outslde source.
The hydrogen and hydrocarbon oll feed may be separately lntroduced to the hydropyrolysls stage or they may be combined and lntroduced as a mixture. The hydro-carbon may be lntroduced through an atomlzing nozzle uslng hydrogen as the atomlzlng gas. Preferably, the hydrocarbon oll is preheated to a temperature approachlng the operating temperature of the hydropyrolysls zone; e.g., 300C to as hlgh as 550C.
The hydropyrolysis ls carried out at temperatures in the range of 600C to 900C, preferably 700C to 850C.
Higher temperatures favor ethylene over ethane. Pressures la67l0s of at least 5 atmospheres gauge are employed, usually in the range o~ 5 to lO0 atmospheres gauge and preferably in the range o~ 15 to 30 atmospheres gauge. Lower pressures ~avor ethylene to ethane. Resldence tlmes ln the range of 0.1 second to 60 seconds, pre~erably 0.5 to 20 seconds, are employed. Shorter residence times ~avor ethylene over ethane.
Carbon deposltion arising ~rom side reactions in the hydropyrolysis zone can be inhibited by provlding a small concentration of æulfur compounds ln the hydrocarbon oil ~eed ir not already present; e.g., lO ppm. This is well known ln the art and ls generally rererred to as pas-si~lcatlon. Usually the addltlon o~ sulfur compounds 18 done on a contlnuous basls.
An alternatlve to the use o~ sul~ur compounds 18 water or steam although for a glven degree Or e~ec-tiveness in inhlbitlng carbonlzation, greater quantlties o~ water are required compared to sulfur compounds.
Usually, up to about 3 mol of water per mol Or hydrocarbon oll wlll be e~fectlve although greater quantltles can be employed. Water not only lnhlblts carbonlzatlon but lt has also been found that water af~ect~ hydropyrolysis by tending to favor ethylene over ethane.
The efrluent from the first--stage hydropyrolysls zone i8 then lntroduced to the second-stage cracking zone.
In the second-stage cracking zone, the ef~luent is sub-~ected to low pressure cracking. Temperatures ln the lQ6~1~S
range o~ 750 to 900C, pre~erably 800-850C, are employed.
Pressures usually not above about 2 atmosphere~ gauge, and preferably not above 1 atmosphere gauge, are used.
The resldence tlme may be ln the range o~ about 0.01 second to 10 seconds wlth 0.1 second to 1 second being pre~erred.
Slnce the condltlons in the second-stage cracklng zone are also ldeal ~or dehydrogenatlng ethane to ethylene, ethane ~rom the separatlon zone 18 recycled to the second-stage cracklng zone. Thus, the second-stage zone not only serves to crack higher hydrocarbons ln the e~luent ~rom the ~irst stage hydropyrolysis zone but also serves to dehydrogenate ethane whlch 18 produced both in the ~lrst and second stages as well as that recycled.
The efrluent product mlxture ~rom the second stage cracklng zone ls then processed for recovery of methane and ethylene ln the separatlon zone. Conventional technlques ~or separatlng hydrogen, methane, ethylene, ethane and hi~her hydrocarbons may be employed. A con-venlent separation and recovery system lnvolves rapldly coollng or quenchlng the product mlxture lmmedlately on exltlng from the second-stage cracklng zone and then processlng the cooled mlxture through a serles of low-temperature ~ractional dlstlllatlon columns as are known ln the art. Hydrogen ls ~lrst separated and recycled to the flrst-stage hydropyrolysls zone as earller dlscussed.
Methane ls then separated and recovered and may be con-veniently utillzed as a synthetic natural gas component.
Ethylene ls next to be separated and may be sent to 3o storage or transport as an ltem of commerce. Ethane ls ~ 6 --1~67105 next separated and recycled to the second-stage cracking zone as earller described. The remalnlng hlgher hydro-carbons are then hydro~enated ln a conventlonal manner to remove any unsaturatlon and recycled to the flrst-stage hydropyrolysls zone to again be processed and con- `
verted to lower hydrocarbons and eventually to ethylene and methane.
Whlle the above technlque for separation ls essentlally a selectlve step-wlse dlstlllation, it should also be mentloned that the reverse may also be employed, that ls, a ~elec~lve step-wise condensatlon.
Slnce the hlgher hydrocarbons wlll contaln ~`
varylng amounts Or aromatics, principally benzene, toluene, and xylenes, a ~urther separatlon step may be performed prlor to hydrogenatlon and recycle. Such separatlon may be accompllshed in any known manner to separate essentlally -all aromatics or only those components deQired. If essen-tlally all aromatlcs are separated, the remainlng higher hydrocarbon stream may be recycled as is to the first-stage hydropyrolJsis zone without hydrogenatlon. It ls preferred, however, to hydrogenate the higher hydrocarbon stream prior to recycle even though the aromatics or some of the aromatics have been removed.
The followlng examples wlll æerve to further lllustrate the lnventlon.
Example l A mlxture of 2.3 llquld vol/min kerosene (bolllng polnt range of 190C to 270C and a specifJc gravlty of 0.82), 2.65 liquid vol/mln water and 161 gas vol/min hydrogen (mol ratio of H2 to hydrocarbon ls about lQ671~5 18.0) are lntroduced to the ~irst-stage hydropyrolysls zone of a type descrlbed in U.S. 3,363~024. Recycle hydrogen and recycle hlgher hydrocarbon inlets are also provided. The hydropyrolysls ls conducted at temperatures ranging from 750-800C, a pressure of 20.4 atmospheres gauge and a residence tlme of 7-lO seconds.
The effluent from the first-stage hydropyrolysis zone is then depressured lnto the second-stage cracking zone of a tubular furnace type. An ethane recycle lnlet ls also provlded to this zone. The second-stage cracking iB carried out at temperatures of 850-900C, pressures of 0.7-1.7 atmospheres gauge and a residence tlme ranglng from 0.1-0.5 second.
The product mlxture from the second-stage hydro-pyrolysls zone ls rapldly cooled or quenched and conducted lnto a ~erles Or fractlonal dlstillatlon columns. Hydro-gen is separated and recycled to the flrst-stage hydro-pyrolysis zone. Methane i8 separated and sent to storage.
Ethylene 18 separated and sent to storage. Ethane is separated and recycled to the second-stage cracking zone.
The remainlng hlgher hydrocarbon stream is hydrogenated and recycled to the flrst-stage hydropyrolysls zone.
Example 2 A llght naphtha (BP 85-150C) at a rate of 0.034 ml/min and hydrogen at a rate Or 100 cc/mln (mol ratio of hydrogen to hydrocarbon o~ about 16.2) were lntroduced to a hydropyrolysis zone formed by a 3/8-lnch stalnless steel tubular reactor one foot ln length Or which a volume of about 16 cc in the central area constituted the hot zone. The hydropyrolysis was carried out at a ; - 8 -~,Q67105 - `
temperature Or 750C (hot polnt), a pressure of 6.8 atmos-pheres gauge and an average resldence tlme o~ 2.5 sec.
The efrluent from the hydropyrolysis zone was analyzed by GLC as 12.4 weight percent H2, 36.3 welght percent methane, 1.1 weight percent ethylene, 41.4 weight : .
percent ethane, and 9.0 welght percent higher hydrocarbons.
The e~luent rrom the hydropyrolysls is then introduced to second-stage cracklng operated under atmos- -pherlc pressure and 800-850C. Calculatlons based on thermodynamlc equlllbrlum at 850C lndlcate a product ~
contalnlng a hydrocarbon distrlbution as rOllOws: :
41 welght percent methane, 23.4 welght percent ethylene, 26.6 weight percent ethane, 4.9 welght percent benzene, and 4.1 welght percent higher hydrocarbons.
~he methane, ethylene, and benzene are recovered, ~.
the hydrogen and hlgher hydrocarbons are re¢ycled to the hydropyrolysls zone and the ethane ls recycled to the second-stage cracklng zone.
: Thus, havlng descrlbed the lnventlon ln detall, lt wlll be understood by those s~llled in the art that certaln varlatlons and modlrlcatlons may be made wlthout departlng rrom the splrit and scope Or the lnventlon as descrlbed hereln and derlned ln the appended claims.
. ......................... .
Claims (9)
1. A process for producing ethylene from higher hydrocarbons comprising (a) introducing a hydrocarbon oil and hydro-gen to a first-stage hydropyrolysis zone, the mol ratio of hydrogen to hydrocarbon oil being at least 1/1;
(b) hydropyrolyzing the hydrocarbon oil in the presence of the hydrogen in said zone under conditions of temperatures in the range of about 600°C to 900°C, pressures of at least about 5 atmospheres gauge and resi-dence times in the range of about 0.1 to 60 seconds, to produce a hydropyrolysis effluent;
(c) introducing the hydropyrolysis effluent to a second-stage cracking zone and subjecting said effluent to cracking conditions of temperatures in the range of about 750°C to 900°C, pressures not in excess of about 2 atmospheres gauge and residence times in the range of about 0.01 to 10 seconds, to produce a cracking zone effluent;
(d) separating said cracking zone effluent into a hydrogen stream, a methane stream, an ethylene stream, an ethane stream, and a higher hydrocarbon stream;
(e) recycling the hydrogen stream to the first stage hydropyrolysis zone and recycling the ethane stream to the second-stage cracking zone;
(f) and recovering the methane stream and ethylene stream.
(b) hydropyrolyzing the hydrocarbon oil in the presence of the hydrogen in said zone under conditions of temperatures in the range of about 600°C to 900°C, pressures of at least about 5 atmospheres gauge and resi-dence times in the range of about 0.1 to 60 seconds, to produce a hydropyrolysis effluent;
(c) introducing the hydropyrolysis effluent to a second-stage cracking zone and subjecting said effluent to cracking conditions of temperatures in the range of about 750°C to 900°C, pressures not in excess of about 2 atmospheres gauge and residence times in the range of about 0.01 to 10 seconds, to produce a cracking zone effluent;
(d) separating said cracking zone effluent into a hydrogen stream, a methane stream, an ethylene stream, an ethane stream, and a higher hydrocarbon stream;
(e) recycling the hydrogen stream to the first stage hydropyrolysis zone and recycling the ethane stream to the second-stage cracking zone;
(f) and recovering the methane stream and ethylene stream.
2. A process according to Claim 1 wherein the hydrocarbon oil has a density of less than about 0.99 and a Conradson carbon content of less than about 20 weight percent.
3. A process according to Claim 1 wherein the conditions of hydropyrolysis are temperatures in the range of about 700°C to 850°C, pressures in the range of about 5 to 100 atmospheres gauge and residence times in the range of 0.5 to 20 seconds.
4. A process according to Claim 3 wherein the hydrogen to hydrocarbon oil mol ratio is in the range of about 3/1 to 30\1.
5. A process according to Claim 3 wherein water is also introduced to the first-stage hydropyrolysis zone.
6. A process according to Claim 3 wherein the second-stage cracking zone conditions are temperatures in the range of about 800°C to 850°C, pressures not in excess of about 1 atmosphere gauge and residence times in the range of 0.1 to 1 second.
7. A process according to Claim 1 wherein the higher hydrocarbon stream is hydrogenated and recycled to the first-stage hydropyrolysis zone.
8. A process according to Claim 1 wherein the higher hydrocarbon stream is separated into an aromatics stream and a remaining stream, recovering the aromatics stream and recycling the remaining stream to the first-stage hydropyrolysis zone.
9. A process according to Claim 8 wherein the remaining stream is hydrogenated prior to recycling.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA228,935A CA1067105A (en) | 1975-06-10 | 1975-06-10 | Two-stage hydropyrolysis cracking process for producing ethylene |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA228,935A CA1067105A (en) | 1975-06-10 | 1975-06-10 | Two-stage hydropyrolysis cracking process for producing ethylene |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1067105A true CA1067105A (en) | 1979-11-27 |
Family
ID=4103292
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA228,935A Expired CA1067105A (en) | 1975-06-10 | 1975-06-10 | Two-stage hydropyrolysis cracking process for producing ethylene |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1067105A (en) |
-
1975
- 1975-06-10 CA CA228,935A patent/CA1067105A/en not_active Expired
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