Abstract:
In a coal liquefaction process including recycle to the liquefaction zone of a product slurry containing mineral residue, the minimum slurry recycle rate is determined by a pumpability constraint on the solids level of the slurry contained in the feed coal mixing vessel. If the solids level in the feed coal mixing vessel rises above the constraint level, the slurry recycle rate must increase. For coals which generate a high mineral residue content, adequate dilution of the slurry in the feed coal mixing vessel requires the slurry recycle rate to rise to an economically impracticable level. To avoid a high recycle rate the catalytic advantage of recycle solids is increased by reducing the median diameter of the particles in the recycle slurry stream by passing a portion of the product slurry through a hydroclone to produce a second recycle slurry comprising hydroclone overflow. The process employs a plurality of feed coals, one of which upon dissolution generates smaller and more catalytically active particles of mineral residue than the other. The hydroclone overflow stream selectively concentrates in the recycle slurry the smaller mineral residue particles generated from said feed coal.
Abstract:
In a coal liquefaction process which includes a recycle of a product slurry which contain recycle mineral residue and recycle of extraneous catalytic material to said liquefication zone, hydrocracking of the hydrocarbonaceous material from the mineral residue occurs and a mixture of hydrocarbon gases, dissolved liquid, normally solid dissolved coal, suspended mineral residue and suspended extraneous catalytic mineral results. A first portion of said residue slurry is recycled to the liquefication zone, a second portion is passed to separation means and the third portion goes to a hydroclone. Overflow from the hydroclone goes to the liquefaction zone to reduce the median diameter of the particles recycled.
Abstract:
A process for liquefying coal involving heating only a portion of a the total process hydrogen stream to increase its temperature to a relatively high level and admixing said heated hydrogen with only a portion of the total coal slurry in the upstream region of a dissolver zone. The hydrogen stream has a relatively low specific heat and the addition thereto of a relatively small amount of heat increases its temperature to a level which is sufficiently high to initiate hydrocracking reactions when the hot hydrogen stream is intermixed with only a portion of the dissolver feed slurry, provided that the dissolver feed slurry contains recycle mineral residue in an amount adequate to catalyze hydrocracking reactions. Because the recycle mineral residue catalyzes the exothermic hydrocracking reactions, sufficient process heat is generated to permit addition to the dissolver zone in a downstream region thereof the remainder of dissolver feed slurry and process hydrogen in a relatively cool condition.
Abstract:
Conversion of raw coal to distillate liquid and gaseous hydrocarbon products by solvent liquefaction in the presence of molecular hydrogen employing recycle of mineral residue is commonly performed at a higher thermal efficiency than conversion of coal to pipeline gas in a gasification process employing partial oxidation and methanation reactions. The prior art has disclosed a combination coal liquefaction-gasification process employing recycle of mineral residue to the liquefaction zone wherein all the normally solid dissolved coal produced in the liquefaction zone is passed to a gasification zone for conversion to hydrogen, where the amount of normally solid dissolved coal passed to the gasification zone is just sufficient to enable the gasification zone to produce the process hydrogen requirement. An unexpected improvement in the thermal efficiency of the combination process is achieved by increasing the amount of normally solid dissolved coal prepared in the liquefaction zone and passed to the gasification zone to enable the gasification zone to generate not only all of the hydrogen required by the liquefaction zone but also to produce excess synthesis gas for use as process fuel. The gasification zone operates with steam and oxygen injection rates resulting in elevated temperatures in the range 2,200.degree. to 2,600.degree. F. which enhance thermal efficiency by accomplishing nearly complete oxidation of carbonaceous feed. These high temperatures produce a synthesis gas relatively richer in CO than H.sub.2. Because the synthesis gas is utilized as fuel, hydrogen can be recovered from the synthesis gas without degrading the value of the remaining CO-concentrated stream, since the combustion heating value of a concentrated CO stream is about the same as that of an H.sub.2 -rich synthesis gas.
Abstract:
Conversion of raw coal to distillate liquid and gaseous hydrocarbon products by solvent liquefaction in the presence of molecular hydrogen employing recycle of mineral residue is commonly performed at a higher thermal efficiency than conversion of coal to pipeline gas in a gasification process employing partial oxidation and methanation reactions. The prior art has disclosed a combination coal liquefaction-gasification process employing recycle of mineral residue in the liquefaction zone wherein all the normally solid dissolved coal produced in the liquefaction zone is passed to a gasification zone for conversion to hydrogen, where the amount of normally solid dissolved coal prepared and passed to the gasification zone is just sufficient to enable the gasification zone to produce the exact hydrogen requirement of the process. The present invention provides an unexpected improvement in the thermal efficiency of the combination process by utilizing formulas based on feed coal characteristics to calculate an amount of normally solid dissolved coal to be prepared in the liquefaction zone and passed to the gasification zone to enable the gasification zone to generate not only all of the hydrogen required by the liquefaction zone but also to produce synthesis gas for use as fuel in the liquefaction zone. It would have been expected that shifting some of the processing load from the ordinarily more efficient liquefaction zone to the ordinarily less efficient gasification zone would decrease process efficiency, but the present combination process unexpectedly achieves an overall efficiency increase by said shift.
Abstract:
A process for converting coal to liquid hydrocarbonaceous products involving a liquefaction reaction in the presence of a coal derived recycle slurry and a non-coal derived solvent comprising a hydrocarbonaceous oil or distillation bottom residue thereof intrinsically contaminated with greater than 300 ppm total of vanadium and nickel. The liquefaction reaction is performed under hydrogen pressure (approximately 500-4000 psi) and under elevated temperature (approximately 300.degree.-500.degree. C.) using a weight ratio of non-coal derived solvent to coal of about 1/1 or less. The conversion of coal to liquids is greatly enhanced by the use of such a non-coal derived solvent under these conditions.
Abstract:
An integrated coal liquefaction-gasification-naphtha reforming process wherein the slurry containing substantially the entire yield of normally solid dissolved coal produced in the liquefaction zone constitutes the only hydrocarbonaceous feed for the gasification zone and wherein substantially all of the naphtha fraction produced in the liquefaction zone is passed through the reforming zone for conversion to gasoline. The cost in terms of thermal efficiency for performing the reforming step is very low when the amount of syngas produced in the gasification zone is adequate to provide upon direct combustion a considerable proportion of the fuel requirements of both the liquefaction and reformer zones.
Abstract:
This invention relates to a combination coal liquefaction-gasification process wherein hydrocarbonaceous mineral residue-containing slurry from the liquefaction zone is recycled to the liquefaction zone and all non-recycled hydrocarbonaceous mineral residue-containing slurry is passed to a gasification zone for conversion to synthesis gas to supply hydrogen for the liquefaction zone. It has now been discovered that in this process a surprisingly high reaction selectivity in favor of the desired distillate oil product is achieved by combining low liquefaction zone residence times and relatively high rates of recycle of mineral residue-containing slurry compared to feed coal rate. Under these conditions the yield of the desired distillate oil product can be increased to an unexpectedly high level while the yields of both higher and lower boiling products are each being decreased and while hydrogen consumption is being reduced.
Abstract:
Pyrite addition to a coal liquefaction process (22, 26) is controlled (118) in inverse proportion to the calcium content of the feed coal to maximize the C.sub.5 --900.degree. F. (482.degree. C.) liquid yield per unit weight of pyrite added (110). The pyrite addition is controlled in this manner so as to minimize the amount of pyrite used and thus reduce pyrite contribution to the slurry pumping load and disposal problems connected with pyrite produced slag.
Abstract:
Conversion of raw coal to distillate liquid and gaseous hydrocarbon products by solvent liquefaction in the presence of molecular hydrogen employing recycle of mineral residue is commonly performed at a higher thermal efficiency than conversion of coal to pipeline gas in a gasification process employing partial oxidation and methanation reactions. The prior art has disclosed a combination coal liquefaction-gasification process employing recycle of mineral residue to the liquefaction zone wherein all the normally solid dissolved coal not converted to liquid or gaseous products in the liquefaction zone is passed to a gasification zone for conversion to hydrogen, where the amount of normally solid dissolved coal passed to the gasification zone is just sufficient to enable the gasification zone to produce the process hydrogen requirement. The process of the present invention provides an unexpected improvement in the thermal efficiency of the combination process by increasing the amount of normally solid dissolved coal prepared in the liquefaction zone and passed to the gasification zone to enable the gasification zone to generate not only all of the hydrogen required by the liquefaction zone but also to produce synthesis gas in an amount adequate to supply all or a significant amount of the fuel requirements of the process. It would have been expected that shifting some of the processing load from the ordinarily more efficient liquefaction zone to the ordinarily less efficient gasification zone would decrease process efficiency, but the present combination process unexpectedly achieves an overall efficiency increase by said shift.