Gasification techniques

While the evaluations of cost and plant size discussed in the preceding paragraphs have been devoted to fixed bed,systems, the conclusions are valid for all coal gasification techniques. Estimates of fluid bed gasifiers have also been prepared. (2) Unfortunately, insufficient data are available to substantiate the operability and actual productivity which must form the basis for any cost estimate. Using these tentative costs, we find that costs for LBG or MBG might be below 3.00/million Btu. For entrained flow systems, still under development, costs in the below 3.00/million Btu range are estimated. However, actual implementation of these advanced systems or even state-of-the-art... 

A steam gasification technique, with oxygen addition, has been described to convert PVC into hydrogen chloride, hydrogen, carbon monoxide and dioxide etc. (187). 

The conversion efficiency of the synthesis gas-to-methanol step is about 85%, and it is usually assumed that improved catalytic gasification techniques are required to raise the overall conversion efficiency above the 51% mentioned above (Faaij and Hamelinck, 2002). The total efficiency will become lower if all life-cycle contributions involving energy inputs, e.g. for collecting and transporting biomass, are included (EC, 1994). 

Note 1 The projected cost of producing hydrogen from coal by proven gasification techniques has been estimated to be competitive with gasoline. 

The gasification techniques can be distinguished related to different criteria such as reactor type (fixed bed or fluidized bed), gasifying agent (air, oxygen, or steam), heat supply into the reactor (directly or indirectly heated) and reactor... 

Analyzes the development and current status of combustion and gasification techniques... 

Physico/chemical processes occuring at high temperatures.The techniques are based on a strong control of all material streams. The processes work relatively independent of the chemical composition of the resource.The chemical composition of the material streams are complex due to the different gasification techniques, many toxic compounds are produced. 

Combustor. In the majority of MHD plant designs the MHD combustor bums coal directly. Because MHD power generation is able to utilize pulverized coal in an environmentally acceptable fashion, there is usually no need to make cleaner fuels from coal, eg, by gasification or by beneficiation. A discussion of combustion techniques for MHD plants is available (70). 

As an example of this technique, the estimated equipment costs for a large coal gasification project have been correlated and programmed for a computer. Thus, it is vei7 easy to get the cost of any one piece, or of many pieces of equipment, for a coal gasification or hydrocarbon processing project once the specification sheets are completed. 

The recycling of PVC by hydrothermal techniques is described, in which PVC is thermally converted in a steam atmosphere into hydrogen chloride, hydrogen, carbon dioxide, carbon monoxide and some gaseous and liquid hydrocarbons. Whilst gasification with only steam is an endothermic reaction, partial combustion of PVC by the addition of small amounts of air, enables autothermic operation of the process to take place. This work deals... 

Techniques for the chemical recycling of plastics into monomers and petrochemical feedstocks are described, including chemical and thermal depolymerisation, pyrolytic liquefaction, pyrolytic gasification and partial oxidation. BRITISH PETROLEUM CO.PLC... 

The addition of steam to the CH4/C02 feedstock to avoid excessive carbon formation is a widely used technique in practical systems [3]. The resulting C02-steam gasification of methane process can be described by the following chemical equation ... 

Pyrolysis experiments were performed using a heated wire grid technique. Reactor details have been reported previously [7, 8]. The technique has been successfully applied in both pyrolysis and gasification studies [8, 10, 11]. In brief, the mesh or grid is housed in a stainless steel chamber known as the grid reactor (Fig. 8.1). The reactor is 227 mm long and has an inner diameter of 15 mm. The grid (9x4 mm) is constructed of interwoven wires (platinum/rhodium 10%)... 

N. Berkowitz (Alberta Research Council) provided a stimulating account of the potential of coal in Canada s energy future. Coal can be used directly as an industrial fuel or be converted to other combustible hydrocarbons. Berkowitz described the three different conversion techniques gasification, liquefaction, and partial conversion techniques to produce gases, oils, and solid fuels. 

M. Greenfeld described unique laboratory experiments designed to stimulate and understand the complex chemistry of in-situ coal gasification. Developed at the Alberta Research Council, the gasification simulator was heavily instrumented with calorimeters and gas chromatographs to determine the enthalpy, composition, and kinetics of formation of the product gases. Computer techniques were used to calculate mass and heat balances and to test kinetic models. 

In chemical terms, the simplest conversion technique is the transformation of coal into a combustible gas by gasification. In its earliest form - introduced in Britain ca. i860 by Sir William Siemens - this involved generation of a producer gas, mainly a mixture of CO, CO2 and nitrogen, by incomplete combustion of coal in air, i.e., by... 

The chemistry of a third group of conversion techniques -i.e., partial conversion methods which skim hydrocarbon gases and/or liquids from the coal and leave a char suitable for use as a boiler fuel or gasification feedstock - is. If anything, even more speculative than the chemistry of liquefaction. 

The first major attempt at precombustion desulphurisation was in the coal gas industry and a number of efficient and effective techniques for removal of H2S, COS, CS2, mercaptans and other volatile sulphur containing products of the gasification process were developed. Many of these techniques found application in the subsequent development of sour natural gas processing where large volumes of hydrogen sulphide had to be removed from the hydrocarbon component. 

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