The experimental research is performed to elucidate the influence of coal properties on the emission characteristics of NOx and the unburned carbon in fly ash from the pulverized coal combustion test facility (coal feed rate is 100kg/ hr). Under the constant experimental condition, the conversion of the fuel bond nitrogen to NOx is increased with the increase in the fuel ratio of the coal and with the decrease of the fuel bond nitrogen content in coal sample. The correlation to predict the NOx concentration from coal properties on pulverized coal combustion was presented and was found to be valid also for the combustion of blended coal. On the other hand, the unburned carbon fraction is increased with the increase of the fuel ratio of the coal. In the blended coal combustion, the unburned carbon fractions in each coal can be assumed to be the same as that of the single kind coal combustion.
The reaction rate constants of nitric oxide decomposition and nitric oxide formation over calcium oxide, calcium sulphate, silica sand and char were measured using a fixed bed reactor at a pressure of 788kPa and temperatures from 500 to 875°C . The reaction rate constant of nitric oxide decomposition over char at 860°C -788kPa was largest among the particles. It was 18.9 (s-1). Calcium oxide, which was produced by calcining limestone, promoted the oxidation of ammonia rather than the decomposition of nitric oxide. The reaction rate constants were 12.7 (s-1) and 1.3 (s-1) respectively. Calcium oxide promoted the oxidation of ammonia rather than calcium sulphate. The amount of calcium oxide must be reduced to decrease nitric oxide. The enhanced catalytic activities were due to active sites in the pores ranging from 400 to 1000A produced by calcination.
In the Brown Coal Liquefaction (BCL) process, a two-stage coal liquefaction process, the solvent de-ashing technique is adopted to remove ash and heavy preasphaltenes from the heavy organic fraction, CLB (Coal Liquid Bottom), of the primary hydrogenation products. In this report, the effects of properties of extraction solvents and production conditions of CLB on the properties of extracts and residues were examined using various solvents and CLBs. In the case of nonpolar solvents, extracts yields of CLB increased in the order of cyclohexane <toluene <tetralin with the increase of BI-PS concentration in the extracts. On the other hand, in the case of oxygen-containing polar solvents such as methanol and acetone, BI-PS concentrations in the extracts were relatively high in spite of low extract yields. Extract yields of CLBs produced under different temperature were predicted by the solvent extraction analysis for nonpolar solvents while not for oxygen-containing polar solvents. These results suggest that polar components of CLB play an important role in the extraction behavior of CLB, resulting in the difference of properties of extracts and residues, which affects their reactivity and the deactivation of catalysts in the secondary hydrogenation and also the handling of residues in the de-ashing process.