Chemistry: fischer-tropsch processes; or purification or recover – Group viii metal containing catalyst utilized for the...
Reexamination Certificate
1999-12-07
2001-03-13
Richter, Johanh (Department: 1621)
Chemistry: fischer-tropsch processes; or purification or recover
Group viii metal containing catalyst utilized for the...
C518S700000
Reexamination Certificate
active
06201031
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;
allowing any gaseous product and unreacted gaseous reactants to disengage from the slurry bed into a head space above the slurry bed;
allowing slurry to pass downwardly from a high level in the slurry bed to a lower level thereof, through at least one dowrcomer located in a first downcomer region of the slurry bed, as well as through at least one further downcomer located in a second downcomer region of the slurry bed, with the second downcomer region being spaced vertically with respect to the first downcomer region, thereby to redistribute solid particles within the slurry bed;
withdrawing any gaseous product and unreacted gaseous reactants from the head space; and
withdrawing liquid phase from the slurry bed, to maintain the slurry bed at a desired level.
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; and the suspension liquid will normally, but not necessarily always, be the liquid product.
The slurry bed may thus be contained or provided in a reaction zone of a slurry reactor or bubble column. By passing or recirculating some of the slurry through the downcomers, more uniform redistribution of the catalyst in the slurry bed than would be the case without such downcomers, is achieved. The slurry reactor or bubble column thus uses a three phase system, ie solid catalyst particles, liquid product, and gaseous reactants and, optionally, 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 and, optionally, gaseous hydrocarbon product. 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 Fischer-Tropsch synthesis reaction is highly exothermic, and the Applicant has surprisingly found that a more uniform distribution of heat is achieved by recirculating some of the slurry through the downcomers in the first and second vertically spaced downcomer regions, in accordance with the invention.
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 catalyst particles greater than 300 microns and less than 5% by mass of the catalyst 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 passing through the slurry bed, ie bubbling through the slurry bed. The gas velocity through the slurry bed is thus sufficiently high to maintain the slurry bed in a state of turbulence or suspension.
According to a second aspect of the invention, there is provided an installation for producing liquid and, optionally, gaseous products from gaseous reactants, the installation comprising
a reactor vessel having a slurry bed zone which, in use, will contain a slurry bed of solid particles suspended in a suspension liquid;
a gas inlet in the vessel at a low level within the slurry bed zone, for introducing gaseous reactants into the vessel;
a gas outlet in the vessel above the slurry bed zone, for withdrawing unreacted gaseous reactants and, when present, gaseous product from the vessel;
at least one downcomer located in a first downcomer region in the slurry bed zone and through which, in use, slurry can pass downwardly;
at least one further downcomer located in a second downcomer region in the slurry bed zone, with the second downcomer region being spaced vertically relative to the first downcomer region, with slurry, in use, also passing downwardly through this downcomer; and
a liquid outlet in the vessel within the slurry bed zone, for withdrawing liquid product from the vessel.
The downcomers or draft tubes are thus located at different levels or vertical elevations within the slurry bed or the slurry bed zone. The second downcomer region may be located at a higher level than the first downcomer region, and, if desired, further downcomer regions, each containing at least one downcomer or draft tube may be provided above the second downcomer region, with a third and any subsequent downcomer regions also being spaced vertically from one another.
In one embodiment of the invention, the second downcomer region may overlap the first downcomer region. In other words, the lower end(s) of the downcomer(s) in the second downcomer region may overlap the uppper end(s) of the downcomer(s) in the first downcomer region. In another embodiment of the invention, however, the second downcomer region may be located in non-overlapping relationship with respect to the first downcomer region. In other words, the lower end(s) of the downcomer(s) in the second downcomer region may be spaced with vertical clearance from the upper end(s) of the downcomer(s) in the first downcomer region.
The downcomer(s) in the second downcomer region may be staggered with respect to that(those) in the first downcomer region, when the reactor or vessel is seen in plan view. In other wards, the lower end(s) of the downcomer(s) in the second downcomer region preferably does(do) not discharge slurry directly above the upper end(s) of the downcomer(s) in the first downcomer region.
Each downcomer may comprise a lower transport section and an upper disengagement or degassing section of greater cross-sectional area than the transport section. The sections are preferably circular in cross-section, is of cylindrical form, with an outwardly upwardly flaring connecting component connecting the disengagement section to the transport section. However, the disengagement section can, if desired, be in another suitable form, eg in the form of a rectangular or triangular section channel, as determined by the space available inside the reactor vessel.
The process may include operating the slurry reactor such that the slurry bed is in a heterogeneous or churn-turbulent flow regime and comprises a dilute phase consisting of fast-rising large bubbles of gaseous reactants, and, possibly gaseous product, which traverse the reaction zone or slurry bed virtually in a plug flow manner, and a dense phase comprising liquid phase, ie liquid product, solid catalyst particles, and entrained smaller bubbles of gaseous re
Nel Herman Gerhardus
Silverman Roy W.
Steynberg Andr{acute over (e )} Peter
(Sasol Technology (Proprietary) Limited)
Ladas and Parry
Parsa J.
Richter Johanh
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-2525637