Herein is yet another Coal liquefaction process developed by Mobil, prior to their merger with Exxon.
The Coal conversion technology described herein is a sophisticated, integrated process designed to take advantage of the full product "slate" generated by the Fischer-Tropsch indirect process of converting Coal, through the initial production of synthesis gas, into various, and more versatile, hydrocarbons.
That product slate includes the heat energy arising from the controlled oxidation of Coal during syngas production, which Mobil intends using to generate Steam for the purpose of needed hydrogenation.
And, rather than uneconomically "forcing" the conversion of Coal into a narrow product range, through additional reaction and processing steps, Mobil suggests, simply, that we take fullest advantage of the things that are produced.
Some advance excerpts might help to clarify:
"The processing combination of this invention more particularly defined below provides high selectivity for high grade fuel comprising methane, LPG, gasoline and distillate and the amount of high grade fuel produced per pound of coal is high due to the high thermal efficiency of the combination operation."
And:
"The process of the invention is particularly concerned with processing low ratio H2 /CO gases obtained from a coal gasification system of low cost and high fuel efficiency in a particular Fischer-Tropsch syngas conversion operation and catalytic upgrading of synthesis product to produce premium fuels."
In other words, if we don't focus solely on Gasoline production, and thus try to force everything to that end, we can, coincidentally, also co-produce synthetic Methane and LPG, and the profits from those help to reduce the effective production cost of the Gasoline.
There might be other benefits, as well, as we point out following excerpts from:
"United States Patent 4,252,736 - Conversion of Synthesis Gas to Hydrocarbon Mixtures
Date: February, 1981
Inventor: Werner Haag, et. al., NY and NJ
Assignee: Mobil Oil Corporation, VA
Abstract: In the conversion of coal to gaseous and liquid products, the heat value of the coal is more completely retained by the products through the selective high efficiency conversion of coal to a low ratio syngas utilizing a portion of the Fischer-Tropsch generated heat recovered as steam, conversion of the low ratio syngas with a water gas shift F-T catalyst to a product comprising C1 to C50 hydrocarbons and oxygenates, converting the F-T product to premium gas and increased liquid fuels comprising gasoline and distillate with a special zeolite catalyst and recovering the SNG and LPG products of the selective steps to provide an improved product slate. A portion of the produced fuel gas is used in lieu of coal to provide some of the heat energy requirements of the combination process.
Claims: In a processing combination comprising the steps of coal gasification to produce H2 and CO, F-T (Fischer-Tropsch) hydrocarbon synthesis from said H2 and CO and upgrading the product of F-T synthesis to produce more desirable gaseous hydrocarbon products, gasoline and distillate material ... .
Background: This invention is concerned with a combination process for converting synthesis gas, i.e. mixtures of gaseous carbon oxides with hydrogen or hydrogen donors, to hydrocarbon mixtures. In one aspect, the invention is concerned with a sequence of process steps for providing low ratio synthesis gas of less than 1 H2 /CO ratio and conversion thereof to premium hydrocarbon fuels including distillates and gasoline boiling range hydrocarbons. The process of the invention is particularly concerned with processing low ratio H2 /CO gases obtained from a coal gasification system of low cost and high fuel efficiency in a particular Fischer-Tropsch syngas conversion operation and catalytic upgrading of synthesis product to produce premium fuels.
Summary: This invention is concerned with an improved combination process for obtaining premium fuels comprising gases, gasoline and higher boiling hydrocarbon distillates from coal. More particularly, the present invention is concerned with a combination process which more efficiently converts coal to premium gas and liquid products.
It has been found that a coal, coke or coal char gasifier with a low steam to oxygen ratio as well as low steam to coal ratio, such as provided by the British Gas Corporation-Lurgi slagging gasifier, has significant advantages in terms of thermal efficiency and cost and can lead to a reduction of up to 20-40% in syngas production costs.
It has been found that a coal, coke or coal char gasifier with a low steam to oxygen ratio as well as low steam to coal ratio, such as provided by the British Gas Corporation-Lurgi slagging gasifier, has significant advantages in terms of thermal efficiency and cost and can lead to a reduction of up to 20-40% in syngas production costs.
The processing combination of this invention ... provides high selectivity for high grade fuel comprising methane, LPG, gasoline and distillate and the amount of high grade fuel produced per pound of coal is high due to the high thermal efficiency of the combination operation. "
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As we understand the full and lengthy Disclosure, a simpler Coal gasifier of lower initial capital cost can be utilized if, instead of trying to force production of synthesis gas having a specific composition from Coal, we take the "low ratio H2 /CO gases obtained" and process them so that we get a range of products, which include "methane, LPG" and "gasoline", and use a "portion of the produced fuel gas ... in lieu of coal to provide some of the heat energy requirements of the combination process".
Moreover, and, again, as our limitations allow us to understand it, some of the heat generated by the partial oxidation of Coal, during syngas production, is used to generate Steam for further, down stream, hydrogenation reactions that serve to produce the hydrocarbon gasses and liquids.
Finally, note that Methane is one of the specified products arising from this process of Coal conversion, and remember that Methane can be reacted, "bi-reformed" and "tri-reformed", with reclaimed Carbon Dioxide, as per Penn State University, and others, as in other of our reports, thus recycling that accused greenhouse pollutant in the synthesis of higher hydrocarbons, which can include, we believe, the valuable liquid fuel, and plastics manufacturing raw material, Methanol.