Conversion processes liquefaction

Imperial Chemical Industries (ICI) operated a coal hydrogenation plant at a pressure of 20 MPa (2900 psi) and a temperature of 400—500°C to produce Hquid hydrocarbon fuel from 1935 to the outbreak of World War II. As many as 12 such plants operated in Germany during World War II to make the country less dependent on petroleum from natural sources but the process was discontinued when hostihties ceased (see Coal conversion PROCESSES,liquefaction). Currentiy the Fisher-Tropsch process is being used at the Sasol plants in South Africa to convert synthesis gas into largely ahphatic hydrocarbons at 10—20 MPa and about 400°C to supply 70% of the fuel needed for transportation. 

C. D. Kalfadelis and E. M. Magee, Evaluation of Pollution Control in Fossil Fuel Conversion Processes, Liquefaction, Section 1, COED Process, EPA-650/2-74-009e, Environmental Protection Agency, Washington, D.C., 1975. 

Coal Liquefaction, Steam is used to produce hydrogen for the liquefaction of coal. In the liquefaction process, coal is crushed, dried, pulverized, and then added to a solvent to produce a slurry. The slurry is heated, usually in the presence of hydrogen to dissolve the coal. The extract is cooled to remove hydrogen, hydrocarbon gases, and hydrogen sulfide. The liquid is then flashed at low pressure to separate condensable vapors from the extract. Mineral matter and organic soHds are separated and used to produce hydrogen for the process. The extract may be desulfurized. The solvent is separated from the products. There are at least six different liquefaction processes (see Coal conversion process, liquefaction Fuels, synthetic-liquid fuels). 

Thermochemical conversion processes use heat in an oxygen controlled environment that produce chemical changes in the biomass. The process can produce electricity, gas, methanol and other products. Gasification, pyrolysis, and liquefaction are thermochemical methods for converting biomass into energy. 

If the mobile phase is present in a significant concentration, as suggested by the results of solvent extraction studies (1,8), the practical meaning of the mobile phase to coal conversion processes may be profound. In coal liquefaction, two stage processes emphasizing the mobile phase and the macromolecular structure separately could well be most economical. In devolatilization kinetics, at least two sets of kinetic parameters are necessary to model the devolatilization phenomena associated with the mobile phase and the macromolecular structure respectively since the mobile phase components devolatilize at much lower temperatures than the macromolecular structure components 0. In addition, the mobile phase appears to have a significant influence on the thermoplastic properties of coal (0 and thereby on coke quality. 

This paper touches on the chemistry of coal gasification and liquefaction comments on the current status of conversion processes and the influence of coal properties on coal performance in such processes and examines the contributions which coal conversion could make towards attainment of Canadian energy self-sufficiency. Particular attention is directed to a possible role for the medium-btu gas in long-term supply of fuel gas to residential and industrial consumers to linkages between partial conversion and thermal generation of electric energy and to coproduction of certain petrochemicals, fuel gas and liquid hydrocarbons by carbon monoxide hydrogenation. 

Hydrogen sulfide is a by-product of many industrial operations, eg, coking and the hydrodesulfurization of crude oil and of coal. Hydrodesulfurization is increasing in importance as the use of high sulfur crude oil becomes increasingly necessary (see Petroleum, refinery processes). A large future source of hydrogen sulfide may result if coal liquefaction attains commercial importance (see Coal CONVERSION processes). 

Energy demand, the implementation of sulfur oxide pollution controls, and the future commercialization of coal gasification and liquefaction have increased the potential for the development of considerable supplies of sulfur and sulfuric acid as a result of abatement, desulfurization and conversion processes. Lesser potential sources include shale oil, domestic tar sands and heavy oil, and unconventional sources of natural gas. Current supply sources of saleable sulfur values include refineries, sour natural gas processing and smelting operations. To this, Frasch sulfur production must be added. 

When coal, oil shale, or tar sands are pyrolyzed, hydrogen-rich volatile matter is distilled and a carbon-rich solid residue is left behind. The carbon and mineral matter remaining behind is the residual char. Pyrolysis is one method to produce liquid fuels from coal, and it is the principal method used to convert oil shale and tar sands to liquid fuels. Moreover, as gasification and liquefaction are carried out at elevated temperatures, pyrolysis may be considered the first stage in any conversion process. 

Nishida, N. and Ishida, M., "Evaluation of Coal Conversion Processes from an Energy Efficient Use Viewpoint (IV) Energy and Exergy Analysis of Liquefaction Process,"... 

The 1973 petroleum crisis intensified research on coal liquefaction and conversion processes. The technology developed in this field was later harnessed in chemical recycling of plastics. Mastral et al. [32], for example, employed two different batch reaction systems (tubing bomb reactors and magnetically stirred autoclave) and a continuous reactor (swept fixed bed reactor). Chemical recycling techniques such as pyrolysis [28, 33-38] or coliquefaction with coal [39, 40] convert plastic wastes into hydrocarbons that are valuable industrial raw materials. 

For shorter distances of transport, e.g., from central stores to filling stations, all the forms of transport can in principle be contemplated. The conversion or liquefaction/deliquefaction processes may carry too high energy losses and costs, so that despite the bulkiness of compressed hydrogen it may be a more acceptable solution. 

Biomass pyrolysis though is one of the fint process man developed, is being studied extensively since the last two decades to obtain liquid, gaseous and solid fuels and chemicals. It is well recognised that pyrolysis plays a key role in any of the thermochemical conversion process be it combustion, gasification, liquefaction, production of char or active carbon. In this context, selection of feedstock and optimal utilisation of the products can play a vital role [1], This paper suggests a criteria to select an appropriate biomass or find its relative suitability to the conversion processes. 

Pyrolysis results are very important for coal characterization, as all conversion processes of coal such as combustion, liquefaction, and gasification start with a pyrolytic step. For this reason, pyrolysis was frequently used for the analysis of coals [17,18). Pyrolysis data were correlated with coal composition, coal characterization and ranking [18a], prediction of coal reactivity as well as of other properties related to coal utilization. Techniques such as Py-MS, Py-GC/MS with different ionization modes, Py-FTIR, or evolved gas analysis (EGA) [19] were described for coal analysis. Programmed temperature pyrolysis is another technique that has been proposed [17] for a complete evaluation of the two types of molecules present in coal. 

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