Separation of catalyst from slurry bubble column wax and catalyst recycle
AssigneeMobil Oil Corporation
InventorsJames A. Brennan, Arthur W. Chester, Yung-Feng Chu
Life of this patent
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Abstract
A process for removing catalyst fines from the wax product produced in a slurry Fischer-Tropsch reactor comprises removing the wax product from the reactor and separating the catalyst fines by passing the wax product through a high gradient magnetic field, whereby the catalyst fines are held by a magnetized filter element and the wax product passes through unhindered to form a purified wax product which is ready for upgrading. The separated catalyst fines are returned to the reactor by backwashing the filter element.
Claims33
In an improved process for converting synthesis gas comprising hydrogen and carbon monoxide to hydrocarbons by means of a slurry Fischer-Tropsch synthesis wherein a catalyst having activity for reducing carbon monoxide is dispersed in a liquid to form a slurry in a reaction zone and a wax product is produced by said synthesis in said reaction zone, said wax product having magnetic catalyst fines contained therein, the improvement comprising:
- removing said wax product from said slurry and passing said removed wax product through high magnetic field gradients, said high magnetic field gradients being produced by a magnetic filter element placed between the poles of a magnet, said wax product being passed through said filter element, whereby said catalyst fines are held by said magnetic field gradients and separated from said wax product to yield a purified wax product and separated catalyst fines, turning off said magnetic field, and backwashing said filter element with a portion of said purified wax product to return said catalyst fines to said slurry in said reaction zone, whereby the ratio of catalyst-to-slurry is maintained substantially constant.
In a processing combination comprising the steps of coal gasification to produce H.sub.2 and CO, Fischer-Tropsch hydrocarbon synthesis from said H.sub.2 and CO and upgrading the product of Fischer-Tropsch synthesis to produce more desirable gaseous hydrocarbon products, gasoline and distillate material wherein said coal gasification is carried out in a gasifier characterized by:
- (1) being capable of producing syngas with less than 30 lbs. of steam per MSCF of syngas,
- (2) producing a low ratio syngas with a H.sub.2 /CO ratio of 0.4 to 1, and
- (3) a gasifier exit gas temperature of less than 2000.degree. F.,
- and said low ratio H.sub.2 /CO syngas is fed to a Fischer-Tropsch Syngas conversion zone comprising a catalyst providing water gas shift and CO-reducing characteristics in a single or a combination of catalyst particles in direct contact with a suspending liquid medium providing temperature control of the exothermic syngas conversion reaction about the particle of catalyst,
- recovering heat from said Fischer-Tropsch syngas conversion zone in the form of medium pressure steam and utilizing said steam in said coal gasifier or its associated oxygen generation plant;
- recovering a product of said Fischer-Tropsch syngas conversion comprising a hydrocarbon in a range of C.sub.1 -C.sub.80 hydrocarbons and oxygenates, and
- converting at least a portion of the hydrocarbons and oxygenates recovered from said Fischer-Tropsch operation with a special crystalline zeolite catalyst of the ZSM-5 type to premium products comprising gaseous LPG products, gasoline and distillate material;
- the improvement which comprises:
- continuously removing a wax product stream in the range of C.sub.10 -C.sub.80, which has accumulated in the conversion zone, said wax product having magnetic catalyst fines contained therein and continuously passing said removed wax product stream through at least one of two high magnetic field gradients, each of said high magnetic field gradients being produced by a magnetic filter element placed between the poles of a magnet, said filter elements being arranged in parallel, said wax product stream continuously being passed alternately through at least one of said parallel filter elements, while the other is being backwashed with purified wax product.
Dependencies are inferred from the claim text.