Coal liquid fuel reduction

Given that biomass can be converted to a liquid product that is primarily phenolic, then oxygen removal and molecular weight reduction are necessary to produce usable hydrocarbon fuels. Upgrading biomass-derived oils differs from processing petroleum fractions or coal liquids because of the importance of deoxygenation. This topic has received only limited attention in the literature (6-11). 

Indeed, since the passage of the original Clean Air Act of 1970, subsequently amended in November 1990, coal preparation efforts in the United States have emphasized development of technology for the reduction of sulfur. One approach to reducing sulfur emissions is accomplished by coal conversion, the direct thermal and/or chemical treatment of coal to produce virtually sulfur-free liquid fuels (Chapters 18 and 19) or gaseous fuels (Chapters 20 and 21) the sulfur can be recovered as a by-product of the conversion process (Chapter 23). 

Combustion of oil produces CO, a contributor to global wanning, and while oil combustion is more efficient than combustion of coal, it is less efficient than natural gas. Oil is unique as a liquid fuel and thus is used predominantly in the transportation sector, making reduction of emissions more challenging. Oil extraction can be damaging to the environment, and more frequently, offshore sources are being... 

There is a large class of industrially important heterogeneous reactions in which a gas or a liquid is brought into contact with a solid and reacts with the solid transforming it into a product. Among the most important are the reduction of iron oxide to metallic iron in a blast furnace the combustion of coal particles in a pulverised fuel boiler and the incineration of solid wastes. These examples also happen to be some of the most complex chemically. Further simple examples are the roasting of sulphide ores such as zinc blende ... 

This was anticipated since the relative nitrogen content of the coal derived liquids 1s higher than either baseline fuel (0.44% versus 0.29% typically). However, the combination of burners out of service and low excess air reduced N0X emissions from the coal derived liquid as much as 50% in some cases (Figures 4 and 5). Table II lists some typical N0X reduction results for the Intensive test matrix. 

Most of the processes discussed either have been or are being used to supply synthetic fuels on a commercial basis. There is, therefore, little question as to the feasibility of these processes. In most cases, however, these ventures have proved and continue to prove economically unattractive in the face of abundant supplies of cheap natural gas and oil. When supplies dwindle and prices escalate, as is likely to happen eventually, specific processes can be expected to become marginally attractive. In the United States, probably the most competitive of the synthetic fuels are shale oil and low-CV and medium-CV gas. The more complex routes to liquid transportation fuels from coal can be expected to be more costly. In all cases a reduction in costs will occur as experience is gained from initial plants. Coal and, eventually, oil shale reserves will, however, also become depleted. Because biomass can probably make only a limited contribution to the total energy demand, other sources of energy will have to be harnessed. The development of synthetic fuels will probably be necessary to obtain the time needed for the evolution of such alternative energy sources. 

Since the late 1940s Royal Dutch/Shell companies have been carrying out research and development work on hydrocarbon synthesis for the conversion of various raw materials, such as coal and natural gas, into liquid transportation fuels. When crude from the Middle East became increasingly available, some reduction in this work occurred, but interest revived in the early 1970s. 

The presence of water in the fuel reduces harmful emissions into the atmosphere and makes the coal explosion-proof. By converting the coal into a liquid form, delivery and dispensing of the fuel can be simplified. One side effect of the CWF production process is the separation of non-carbon material mixed in with the coal before treatment. This results in a reduction of ash yield or the treated fuel, making it a viable alternative to diesel fuel 2 for use in large stationary engines or diesel-electric locomotives. 

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