Sulfur char containing

The char contains no organic sulfur compounds, although some inorganic sulfur (probably FeS2) is present. 

In general, utilization of high-sulfur char as a boiler fuel does not appear to be economically attractive. Char may be utilized as a gasifier feedstock this possibility is particularly attractive when the char contains gasification catalyst used as a coal pretreatment prior to hydrocarbonization. Finally, as noted above, it is possible to optimize hydrocarbonization processes for the production of no net char. 

Modeling of Fluidized Bed Combustion of Coal Char Containing Sulfur... 

It (1 ) deals with the derivation of relations giving the particle size distribution in the bed, overflow, and carryover streams and their respective weights. This theory will be extended to include the effects of particle growth or shrinkage (Z>1 or Z<1). For typical combustion of char containing sulfur followed by sulfur dioxide absorption by limestone, relations will be derived to determine the extent of sulfur retention. The reaction, carryover, and overflow rates will be evaluated with particular attention to their dependence on Z. 

Rehmat, A. Saxena, S. C. Land, R. H. Application of Non-catalytic Gas-Solid Reactoins for a Single Pellet of Changing Size to the Modeling of Fluidized-Bed Combustion of Coal Char Containing Sulfur Argonne National Laboratory Report, ANL/ CEN/FE-80-13, September 1980, 86 pp. 

An empirical approach that included a mathematical model was beneficial in predicting the sulfur content of chars produced from coal over a specified range of operation conditions. The technique was useful for predicting the conditions required for a specified product. For instance, the model for total sulfur indicates that a char containing less than 0.7% sulfur could probably be produced at temperatures and pressures higher than those investigated in this experiment. 

As discussed above, the composition of the solvent used in short contact time conversions can be important. The concentration of H-donors is one factor to be considered. It is known that in long contact time conversions, solvents having high H-donor contents have a better ability to prevent char formation as sulfur is removed from the SRC. Thus, higher yields of upgraded liquids are observed when solvents containing high concentrations of H-donors are used. 

Synthesis of polyethylene terephthalate esters containing up to 4.6 mol% sulfurized terephthalate derivatives as a method of increasing char formation. 

Figure 2 shows the results of the pyrolysis experiments conducted with the Spanish lignite at 750-960°C at residence times of 0.52-0.72 sec. It is seen that under the pyrolysis conditions used, 60 - 70% of the sulfur in this coal appears in the gaseous products as H2S, COS, and CS2. As in the previous sulfur study (1), the principal sulfur gaseous product at all temperatures is H2S, with some CS2 formed at T >840°C. The CS2 is apparently formed at the expense of the H2S, by any of several reactions H2S may react with the carbon of the coal and/or the methane evolved in the pyrolysis of the coal to form CS2- A small amount of COS is detected at all temperatures trace amounts of SO2 are also detected. Moreover, the total sulfur yield appears to reach a maximum about 900°C. The decrease in sulfur volatilization as pyrolysis temperature is increased above 900°C is attributed to sulfur retention in the char due to the reaction of H2S with coke or char to form more stable thiophenic structures (2). GC/MS analysis of the tars (diluted to 10 ml) from the pyrolysis at 750 and 850°C did not reveal any sulfur-containing structures. Tars from the pyrolysis at 900 and 950°C, however, contain dibenzothiophene. 

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