Patent EA-003480-B1 (EA)
Title: Process for converting synthesis gas into higher hydrocarbons
Inventor: KETLEY GRAHAM WALTER
IPC: B01J8/22
Filed: 2000-11-22
Abstract: 1. A process for the conversion of synthesis gas to liquid hydrocarbon products by contacting the synthesis gas at an elevated temperature and pressure with a suspension comprising catalyst suspended in a liquid medium, in a system comprising a tank reactor which is provided at or near the top thereof with at least one injector-mixing nozzle wherein the process comprises the steps of: a) passing the suspension comprising catalyst suspended in the liquid medium through the injector-mixing nozzle where synthesis gas is mixed with the suspension; b) discharging a mixture comprising synthesis gas and suspension from the injector-mixing nozzle in a downwards direction into the tank reactor; c) converting at least a portion of the synthesis gas to liquid hydrocarbon products in the tank reactor to form a product suspension comprising catalyst suspended in the liquid medium and the liquid hydrocarbon products; d) separating a gaseous stream comprising unconverted synthesis gas from the product suspension; e) recycling the separated gaseous stream to the injector-mixing nozzle; and f) recycling at least a portion of the product suspension to the injector-mixing nozzle. 2. A process according to claim 1 wherein the injector-mixing nozzle is executed as a venturi nozzle or a gas blast nozzle. 3. A process according to claim 1 or 2 wherein the synthesis gas is broken down in the injector-mixing nozzle into gas bubbles having diameters in the range 30[mu] to 10 mm. 4. A process according to claim 3 wherein the synthesis gas is broken down in the injector-mixing nozzle into gas bubbles having diameters in the range of from 30[mu] to 3000 [mu]. 5. A process according to any one of claims 1 to 5 wherein the gaseous recycle stream is cooled before being recycled to the injector-mixing nozzle. 6. A process according to claim 5 wherein vaporized low boiling liquid hydrocarbon products and vaporized water by-product condense out of the gaseous recycle stream and are removed therefrom. 7. A process according to any one of claims 1 to 6 wherein the product suspension is cooled before being recycled to the injector-mixing nozzle. 8. A process according to claim 7 wherein additional cooling is provided by means of a heat exchanger positioned within the suspension in the tank reactor. 9. A process according to any one of claims 1 to 8 wherein the tank reactor contains a gas cap and the injector-mixing nozzle discharges either above or below the level of suspension in the tank reactor. 10. A process according to claim 9 wherein the gaseous recycle stream is withdrawn from the gas cap and is recycled to the injector-mixing nozzle. 11. A process according any one of claims 1 to 10 wherein product suspension is withdrawn from at or near the bottom of the tank reactor. 12. A process according to any one of claims 1 to 11 wherein the suspension is at least in part recycled to the injector-mixing nozzle via a slurry recycle line and a slurry pump. 13. A process according to claim 12 wherein the slurry recycle line is provided with a heat exchanger. 14. A process according to any one of claims 1 to 13 wherein the synthesis gas is fed to the injector-mixing nozzle at a pressure of at least 30 bar. 15. A process according to any one of claims 1 to 14 wherein the pressure drop over the injector-mixing nozzle is in the range of from 1 to 6 bar. 16. A process according to any one of claims 1 to 15 wherein a stream comprising low boiling hydrocarbon(s) is introduced into the injector-mixing nozzle and/or the tank reactor. 17. A process according to any one of claims 1 to 16 wherein the system comprises a plurality of injector-mixing nozzles which discharge into a single tank reactor. 18. A process as claimed in claim 17 wherein up to 150 injector-mixing nozzles discharge into a single tank reactor. 19. A process according to any one of claims 1 to 18 wherein the liquid hydrocarbon products comprise a mixture of hydrocarbons having chain lengths of from 5 to about 90 carbon atoms. 20. A process according to any one of claims 1 to 19 wherein the catalyst is iron, cobalt or ruthenium supported on silica, alumina, silica-alumina, titania or zinc oxide. 21. A process according to any one of claims 1 to 20 wherein the catalyst has a particle size of less than 50 microns. 22. A process according to any one of claims 1 to 21 wherein the catalyst has a particle size in the range 5 to 30 microns. 23. A process according to any one of claims 1 to 22 wherein the suspension discharged into the tank reactor comprises 10 to 30% wt of catalyst particles. 24. A process according to any one of claims 1 to 23 in which the tank reactor is maintained at a temperature of 180-280 degree C. and a pressure of 5-50 bar. 25. An apparatus which comprises a plurality of injector-mixing nozzles, a tank reactor, a gas recycle line having a first end and a second end and a slurry recycle line having a first end and a second end wherein: a) the plurality of injector-mixing nozzles are arranged at or near the top of the tank reactor; b) each injector mixing nozzle has a first inlet for a suspension of a catalyst in a liquid medium, at least one second inlet for synthesis gas and an outlet which is positioned within the tank reactor for discharging a mixture of synthesis gas and the suspension from the injector-mixing nozzles in a downwards direction into the tank reactor, c) the tank reactor has a first outlet for discharging a product suspension at or near the bottom thereof and a second outlet for a gaseous recycle stream at or near the top thereof; d) the first end of the slurry recycle line is in communication with the first outlet of the tank reactor and the second end of the slurry recycle loop is in communication with the first inlet of the injector-mixing nozzles; and e) the first end of the gas recycle line is in communication with the second outlet of the tank reactor and the second end of the gas recycle line is in communication with the second inlet(s) of the injector-mixing nozzles. 26. An apparatus according to claim 25 wherein the slurry recycle line is provided with a slurry pump and a heat exchanger. 27. An apparatus according to claim 25 or 26 wherein the gas recycle line is provided with a heat exchanger. 28. An apparatus according to claims 25 to 27 wherein the apparatus has up to 150 injector-mixing nozzles. 29. An apparatus according to any one of claims 25 to 28 wherein the tank reactor has a heat exchanger positioned therein.