SYMPOSIUM ON RODUCTION OF SYNTHESIS GAS I’rwwnled behre t h e Ibiviai-n
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G u s aiod Fuel 4:heniistry a i l I t
3 1 e l i n g of ihn Aniericiin (:iieniicuI Seviely, New York.
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Introductory remarks A. R. POWELL, Koppem Company, Inc., Pittsburgh, Pa. 3‘
ITH thepresentdemdforhquidfuelafarexceedingthat of the yeam immediately preceding the recent war and with +bll founded indications that this demand will further inmesse, it ahodd cause little wonder that the search.for substitute .liquid fuels, including development of synthetic pmesses, is today being pushed aggrea9ively. This search for substitutes end the Rsearch and development neoesssry for future produc;tib of synthetic liquid fuels are being accelerated very rapidly, &d it now appears likely that the synthesis of liquid fuels will prove to be one of the major technical developments in this country during the next decade or two. T h e history of tbese developments, particularly in Germany,,is now well known. Much valuable research along these linea has been oarried out by the Germans and, more important stiil, these research findings were incorporated into huge operating plants that provided the Nazi war machine with 29% of its liquid-fuel requirements a t the peak of the war. This sounds .very impressive until it is Ralised that this 29% of the German liquid-fuel requirement waa equivalent to leas than 2% of American wartime crudeoil production. In other words, if we in America ever have to produce synthetic liquid fuel in a volume e q u i d e n t t o our recent wartime production of crude oil, we shall require a capacity over 6fty times that of this relatively huge industry of the Germans. Thia situation poses problems of incredible magnitude. All who went to Germany t o investigate this industry before the war and-who later examined it in more detail aa members of government miasions during the latter stages of the war believe that the future will show that the German developments, impressive an t b are, represent o d y the brave begbinga of an industrystillinitsinfancy. Theprohlemsaheadare largely of an engineering or economic nature, hut chemistry is alw certain to play FA major role in the m y technical and economic improvemente that are to come. From the long-range standpoint, at least, the pro$luction of low++ synthesis gas is prohahly the most difficult and also the moet important problem connected with the liquid-fuels propam
that must be solved. Synthesis gas is the mixture of hydrogen and carbon monoxide that serves aa the Bingle major raw material for the Fischer-Tropach type of synthetic liquidfuel process, snd this mixture may also serve 88 the source of hydrogen t o hydrogenate coal t o liquid fuel in the Bergins type of process. Therefore, irmpective of the type of proceim used, synthesis gas is essential and it must be produced cheaply in order t o make liquid fuels at a cost not too far in exof present costs of ma!&g gasoline and fuel oils from natural petroleum. One fact that is often overlooked in discueaions of this subject is that synthesis gas, for purposes other than liquid-fuel synthesis, Is being and has been manufactured in ow country for a great many years in a volume that appears impreesive at firat sight. It has usually been known as blue water gss, hut, just the same, it is a mixture of hydrogen and carbon monoxide that can be used for Fischer-Tropach synthesis with paeaihly proper adjustment of the ratio of hydrogen t o carbon monoxide. As a matter of fact, German Fischer-Tropsch operations were almost entirely carried on through the uee of blue water gas made from coke’in the usual equipment. Why is it, then, that the orthodox blue water gas process with coke as the fuel, now so widely used in the manufactured-gas industry and in the chemieal industry for the manufacture of synthetic ammonia, methanol, etc., cannot be adapted to this future synthetic liquid-fuel busineas in this country? The answer t o this question is almost entirely one of economics. If thecost of syntheticoilisnot tobetoomuchgeaterthanpreaent prices of crude petroleum, it is essential that the cost of synthesis gas be considerably lower than the p m n t cost of blue water gas. The factors that will bring these lower costs to realieation are: 1. Use of natural gas as the raw material from which the synthesis gas is made. Today natural gas at the well is the cheapest fuel in this country. At least two h g e projected plank using the Fischer-Tmpsch principle will use natural gas aa the raw material for nynthesia-pas production.
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INDUSTRIAL AND ENGINEERING CHEMISTRY
April 1948
2. Use of the cheaper grades of coal with the plants located close to the mine mouth. Even underground gasification of coal, whereby the coal is gasified just as it lies in the seam, has been proposed for production of synthesis gas and this scheme should be studied further, particularly from the standpoint of economics. 3. Erection of very large plants, thereby ensuring the lowest unit investment cost and the greatest operating economies. In this connection, the potentially enormous size of this synthesisgas production must be emphasized. If the equivalent of all our crude-oil production were replaced by plants operating on the Fischer-Tropsch principle, over 50 trillion cubic feet of synthesis gas would be required annually. This is over 100 times the volume of manufactured gas now distributed in our country. From this it appears that the synthesis-gas plants will just naturally be large anyway and that greater economy will follow as a result. 4. Most important of all in securing lower costs will be the research and development efforts that are even ngw well under way and that will swell t o a crescendo within the next few years.
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Chemists and engineers with a background of experience in petroleum technology and those with a background in coal and manufactured-gas technology are today tackling this problem. The coal industry and the petroleum industry fmd here, certainly, a common meeting ground, and some of the present programs are being, and surely more of the future research programs on synthesis gas will be, carried out cooperatively by the two groups. The present symposium was arranged as a means of reporting progress that has been made in the search for new methods of making and purifying synthesis gas. These nine papers therefore contribute t o the last-named factor-namely, research and development-in working out more economical methods. Admittedly, these papers do not provide the final answers. It is hoped, however, that the papers and the ensuing discussion will stimulate the thinking of those who are interested in and those who are working on this important and interesting problem. A technology that is so closely knit to our future national economy and security as is this one will surely move forward very rapidly.
Oxygen in the production of hydrogen or synthesis gas L. L. NEWMAN,
Bureau of Mines, Washington, D. C .
PROCESSES for the large-scale production of hydrogen and synthesis gas are basically identical. The ratio of hydrogen to carbon monoxide in the synthesis gas may vary from 1 to 2. A plant producing 25,000 barrels of primary liquid fuel per day requires from 700,000,000 to 800,000,000 cubic feet of synthesis gas per day. Low-cost synthesis gas requires the use of lower priced generator fuels, which can best be gasified in continuous internally heated processes using .oxygen. Part, if not all, of the energy requirements for oxygen production may be obtained from the heat evolved in the synthesis reactors. The principal
processes include: Winkler, gasifying fines in a k e d fluidized bed; Koppers, gasifying pulverized coal in suspension; Lurgi, gasifying fines in a fixed bed under pressure; Thyssen-Galocsy and Leuna, gasifying lump fuel and disposing of the ash as a molten slag. Other processes are briefly discussed in relation to the foregoing. I t is concluded that American requirements may best be satisified by gasification processes using pulverized fuel in suspension. These will permit the use of higher rank caking or noncaking coals, as well as the lower rank subbituminous coals or lignite.
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American conditions makes the fourth method questionable because the hydrogen produced has only a small portion of the thermal value of the coal used for coking. The fifth, re-forming of hydrocarbons, is of interest because of the quantity of noncondensable hydrocarbons made available by the hydrogenation process itself. The amount of such hydrocarbons obtained in the liquid-phase coal-hydrogenation process is, however, inadequate to supply the required amount of hydrogen through re-forming. Although the volume of gaseous hydrocarbons from liquid-phase and vapor-phase coal-hydrogenation operations may suffice t o supply the required hydrogen by re-forming methods, they are more valuable for the production of iso-octane by polymerization methods (14). The sixth-catalytic conversion of carbon monoxide in water gas-has been used most widely in the production of hydrogen in the large volumes required for liquid-fuel production and is discussed in another paper in this symposium (66). In general, any process yielding a low-cost water gas would yield, by catalytic conversion of the carbon monoxide, low-cost hydrogen for hydrogenation purposes and low-cost synthesis gas for the Fischer-Tropsch process.
0 OBTAIN engineering and cost data for synthetic liquidfuel processes, the Bureau of Mines has proposed to build demonstration plants for the production of oil by the hydrogenation of coal and the carbon monoxide-hydrogen synthesis. The cost of hydrogen for hydrogenation has been estimated to be one third to one half of the cost of the product, while the cost of synthesis gas consisting of carbon monoxide and hydrogen is the major item of expense in the production of liquid fuel by the Fischer-Tropsch process or some variation of it. There are many methods of producing hydrogen. These include the electrolytic dissociation of water, the reduction of steam by iron at elevated temperatures, the reaction of water and acids with certain metals, the fractional distillation of liquefied gases containing hydrogen-such as coke-oven gas, the re-forming of natural or other hydrocarbon gases, and the catalytic conversion of carbon monoxide in water gas into carbon dioxide and hydrogen \ through the action of steam. Except in unusually well-favored locations, the first three methods have been found generally unsuitable or costly for large scale operations. The remaining three have been in use, to a considerable extent, in European plants. Close scrutiny of
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