Coal conversion capacity

A new countercurrent continuous centrifugal extractor developed in the former USSR (214) has the feature that mechanical seals are replaced by Hquid seals with the result that operation and maintenance are simplified the mechanical seals are an operating weak point in most centrifugal extractors. The operating units range between 400 and 1200 mm in diameter, and a capacity of 70 m /h has been reported in service. The extractors have been appHed in coke-oven refining (see Coal conversion processes), erythromycin production, lube oil refining, etc. 

Sasol Fischer-Tropsch Process. 1-Propanol is one of the products from Sasol s Fischer-Tropsch process (7). Coal (qv) is gasified ia Lurgi reactors to produce synthesis gas (H2/CO). After separation from gas Hquids and purification, the synthesis gas is fed iato the Sasol Synthol plant where it is entrained with a powdered iron-based catalyst within the fluid-bed reactors. The exothermic Fischer-Tropsch reaction produces a mixture of hydrocarbons (qv) and oxygenates. The condensation products from the process consist of hydrocarbon Hquids and an aqueous stream that contains a mixture of ketones (qv) and alcohols. The ketones and alcohols are recovered and most of the alcohols are used for the blending of high octane gasoline. Some of the alcohol streams are further purified by distillation to yield pure 1-propanol and ethanol ia a multiunit plant, which has a total capacity of 25,000-30,000 t/yr (see Coal conversion processes, gasification). 

A bypass type Claus plant, with fired preheating of acid gas and air, has been advocated by some for use in coal conversion plants, for acid gases containing 20 percent H2S or less. The authors think this an unwise choice for synfuels plants, even though it can be a good choice for other purposes. Several preheat-bypass Claus plants (of nominal capacity about 1,000 tons... 

Taken alone, the conversion profile from the protio work is consistent with the view that the conversion of coal is limited by its structure. Thus if the organic portion of coal contained a limited network of breakable links, the scission of which would liberate about 50% of the material to TS product, then runs with increasing conversion capacity would show increased conversion, leveling off at about 50% TS yield. 

Solids. Only very rough approximations of solid heat capacities can be made. Kopp s rule (1864) should only be used as a last resort when experimental data cannot be located or new experiments carried out. Kopp s rule states that at room temperature the sum of the heat capacities of the individual elements is approximately equal to the heat capacity of a solid compound. For elements below potassium, numbers have been assigned from experimental data for the heat capacity for each element as shown in Table 4.2. For liquids Kopp s rule can be applied with a modified series of values for the various elements, as shown also in Table 4.2. For example, the heat capacity at room temperature of Na2S04 lOHaO would be 2(6,2) + 1(5.4) + 14(4.0) + 20(2.3) = 119.8 cal/(g mol)( C). The heat capacity of coal can be estimated from equations in the Coal Conversion Systems Technical Data Book cited in the supplementary references. Consult Reid or Perry s Handbook fpr tables of heat capacity data for solids. 

With the conversion to a mechanical feed system, they expect to double their tdf feed capacity and run 4 tons per hour. This should result in a considerable fuel cost savings, because they can obtain tdf for about 1 per million Btu, whereas they would otherwise be burning more coal which costs about 2 per million Btu. With the new configuration they could obtain 10 percent of their heating value from tdf, 10 percent from natural gas, and 80 percent from coal. Both their old and new configurations utilize 2-inch by 2-inch pieces of tdf. With the new capacity Arizona Portland could increase its capacity to over 3 million scrap tires per year. In 1990, Arizona Portland utilized approximately 1 million scrap tires (54). 

CO/Water Conversions. In contrast to the raore-or-less fixed reducing capacity available in conventional donor systems, the CO/water system offered considerable latitude. We had earlier demonstrated that changes in the initial pH of the system brought about wide variation in the TS yields for Illinois No. 6 coal (6). 

In summary, we find that conversion is not limited by coal structure, but rather by the kinetics of the reducing step(s). Systems with even greater reducing capacity, and where the water gas shift reaction can be suppressed, should provide even higher conversions to toluene-soluble products. The products in turn should be no less rich in hydrogen than those from lower conversion runs. 

Methanol production today is not a sustainable process but is part of a petrochemical route for conversion of fossil carbon into chemicals and fuels (see Section 5.3.3). It has to be emphasized that a one-to-one upscaling of existing industrial methanol synthesis capacities for fuel production is not useful. This is mainly because the current industrial process has not been developed and optimized under the boundary conditions of conversion of anthropogenic C02, but rather for synthesis gas feeds derived from fossil sources such as natural gas or coal. The switch to an efficient large-scale methanol synthesis with a neutral C02 footprint is still a major scientific and engineering challenge, and further research and catalyst and process optimization is urgently needed to realize the idea of a sustainable methanol economy. ... 

Among the different possibilities for conversion of coal to liquid hydrocarbons, at present only the Fischcr-Tropsch synthesis is performed on a commercial scale. Approximately 2000000 t/a of liquid hydrocarbons are produced at Sasol. Republic of South Africa, and a further increase of production capacity is planned. Due to the present situation in South Africa, which... 

NCREASING USE OF FOSSIL FUELS (petroleum, coal, and gas) will continue to load the atmosphere with carbon dioxide beyond the apparent capacity of the plant and oceanic sinks to absorb the gas. There has been an estimated 15% increase in atmospheric carbon dioxide since the turn of the century (/). An active response to this worldwide problem is to capture and chemically convert the carbon dioxide at its source of production. Ironically, these conversion processes must be powered by nonfossil fuel sources (solar or nuclear) to achieve a net reduction in atmospheric carbon dioxide. 

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