Chemistry: fischer-tropsch processes; or purification or recover – Liquid phase fischer-tropsch reaction
Reexamination Certificate
2000-03-27
2001-07-24
Richter, Johann (Department: 1621)
Chemistry: fischer-tropsch processes; or purification or recover
Liquid phase fischer-tropsch reaction
C518S706000, C518S728000
Reexamination Certificate
active
06265452
ABSTRACT:
THIS INVENTION relates to a process for producing liquid and, optionally, gaseous products from gaseous reactants. It relates also to an installation for producing liquid and, optionally, gaseous products from gaseous reactants.
According to a first aspect of the invention, there is provided a process for producing liquid and, optionally, gaseous products from gaseous reactants, which process comprises
feeding, at a low level, gaseous reactants into a slurry bed of solid particles suspended in a suspension liquid;
allowing the gaseous reactants to react as they pass upwardly through the slurry bed, thereby to form liquid and, optionally, gaseous products, with the gaseous reactants and any gaseous product assisting in maintaining the solid particles in suspension in the suspension liquid, and with the liquid product forming, together with the suspension liquid, a liquid phase of the slurry bed;
withdrawing liquid phase from the slurry bed, to maintain the slurry bed at a desired level;
allowing any gaseous product and unreacted gaseous reactants to disengage from the slurry bed and to pass upwardly, together with any entrained solid particles and liquid phase, as a gas phase into a head space above the slurry bed;
treating the gas phase by subjecting it to distillation and, optionally, washing in the head space, thereby to separate any entrained solid particles and liquid phase from the gas phase;
returning any separated entrained solid particles and, optionally, liquid phase to the slurry bed; and
withdrawing the treated gas phase from the head space.
While it is believed that the process can, at least in principle, have broader application, it is envisaged that the solid particles will normally be catalyst particles for catalyzing the reaction of the gaseous reactants into the liquid product, and, when applicable, the gaseous product; the suspension liquid will normally, but not necessarily always, be the liquid product; and that the slurry bed and the head space will normally be provided in a slurry reactor or bubble column.
The slurry bed is thus contained or provided in a reaction zone of the slurry reactor or bubble column, with the distillation being effected in a distillation zone thereof spaced from the slurry bed by a freeboard zone. In other words, the headspace comprises the freeboard zone immediately above the reaction zone, and the distillation zone above the freeboard zone.
The slurry reactor or bubble column thus uses a three phase system, ie solid catalyst particles; liquid product; and gaseous reactants and, optionally, gaseous product.
Furthermore, while it is also believed that, in principle, the process can have broader application, it is envisaged that it will have particular application in hydrocarbon synthesis where the gaseous reactants are capable of reacting catalytically in the slurry bed to form liquid hydrocarbon product(s) and, optionally, gaseous hydrocarbon product(s). In particular, the hydrocarbon synthesis may be Fischer-Tropsch synthesis, with the gaseous reactants being in the form of a synthesis gas stream comprising mainly carbon monoxide and hydrogen, and with both liquid and gaseous hydrocarbon products being produced.
The catalyst of the catalyst particles can be any desired Fischer-Tropsch catalyst, such as an iron-based catalyst, a cobalt-based catalyst, or any other Fischer-Tropsch catalyst. The catalyst particles may have a desired particle size range, eg no particles greater than 300 microns and less than 5% by mass of the particles being smaller than 22 microns.
The slurry reactor or bubble column will thus be maintained at normal elevated pressure and temperature conditions associated with Fischer-Tropsch synthesis reactions, eg a predetermined operating pressure in the range 10 to 50 bar, and a predetermined temperature in the range 160° C. and 280° C., or even higher for the production of lower boiling point product.
The catalyst particles in the slurry bed are thus maintained in suspension by the turbulence created by the synthesis gas stream and any gaseous hydrocarbon products that are formed, passing through the slurry bed, ie bubbling through the slurry bed. optionally, the slurry bed may also be mixed, eg by using mixing devices such as draft tubes or downcomers, to assist in maintaining the catalyst particles in suspension. The gas velocity through the slurry bed is thus sufficiently high to maintain the slurry bedin a state of turbulence or suspension. Draft tubes or downcomers can be used to ensure a more uniform suspension of solids throughout the slurry bed.
The gas phase entering the head space will normally comprise or consist of non-condensible unreacted gaseous reactants, a non-condensible gaseous hydrocarbon fraction, entrained solid catalyst particles, entrained liquid hydrocarbon product, a vapourized liquid hydrocarbon fraction, a condensible gaseous hydrocarbon fraction, and water vapour. The entrained solid catalyst particles will normally be associated with the entrained liquid product in the form of slurry droplets. The treated gas phase which is withdrawn from the distillation zone will normally comprise or consist of the non-condensible unreacted gaseous reactants, the non-condensible gaseous hydrocarbon fraction, the condensible gaseous hydrocarbon fraction, and the water vapour.
The gaseous hydrocarbon products thus comprise the non-condensible gaseous hydrocarbon fraction, the vapourized liquid hydrocarbon fraction, the condensible gaseous hydrocarbon fraction and the water vapour.
The process may then include, in a cooling stage, cooling the treated gas or vapour phase after it has left the distillation zone, thereby to condense at least some of the condensible gaseous hydrocarbon fraction, and returning at least some of this condensed hydrocarbon product to the distillation zone as reflux for the distillation. Thus, the treated gas or vapour phase may typically be cooled to between 30° C. and 50° C., typically to about 40° C., at a pressure as close as practical to the reactor pressure.
By ‘non-condensible gaseous hydrocarbon fraction’ is meant hydrocarbon product that is in gas or vapour form at the prevailing temperature and pressure conditions in the reactor and which does not condense at the prevailing temperature and pressure conditions in the cooling stage.
On the other hand, by ‘condensible gaseous hydrocarbon fraction’ is meant hydrocarbon product that is in gaseous or vapour form at the prevailing temperature and pressure conditions in the reactor and which condenses at the prevailing temperature and pressure conditions in the cooling stage, to form the condensed hydrocarbon product of which at least part is returned to the distillation zone as ref lux. By ‘vapourized liquid hydrocarbon fraction’ is meant hydrocarbon product which is in vapour form at the prevailing temperature and pressure conditions in the reaction zone o f the reactor, and w hich is in liquid form at the prevailing temperature and pressure conditions at the gas phase exit from the distillation zone. The vapourized liquid hydrocarbon fraction is thus heavier, as regards its molecular mass, than the condensible gaseous hydrocarbon fraction. Since the vapourized liquid hydroarbon fraction is in liquid or condensed form at the exit conditions of the distillation zone, it constitutes a portion of the reflux in the distillation zone. The condensed vapourized liquid hydrocarbon fraction which exits the bottom of the distillation zone is also referred to as ‘the liquid hydrocarbon fraction’.
By ‘liquid hydrocarbon product’ is meant product which is in liquid form at the prevailing temperature and pressure conditions in the reactor, and which is in solid or gelled format atmospheric pressure and at a temperature close to ambient temperature. Thus, typically, the liquid hydrocarbon product comprises hydrocarbon molecules containing 20 or more carbon atoms, and thus includes wax.
The distillation may be effected by passing the gas phase upwardly across at least one d installation stage in the distillation zone of the slurry rea
Jones David H.
Silverman Roy W.
Steynberg André Peter
(Sasol Technology (Proprietary) Limited)
Ladas & Parry
Parsa J.
Richter Johann
LandOfFree
Process for producing liquid and, optionally, gaseous... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for producing liquid and, optionally, gaseous..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for producing liquid and, optionally, gaseous... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2554343