No abstract

The gasification in air and in steam of a bituminous coal from Belmcz (Cordoba, Spain) (SAO) and of sampk.~ resulting either from acid treatment (HC1, SAH; HNO 3 SAN and H F, SAF) or from thermal treatment (SAOC) has been studied under dynamic conditions.For gasitication in air, the sequence of variation of the reactivity is SAN > SAF > SAlt > SAO at lower gasification temperatures, and SAF>SAII>SAN>SAO at higher treatment temperatures. In steam, however, the sequence is SAF > S,('O, SAH > SAN in the whole interval of gasification temperatures. SAOC shows a reactivity much lower than SAO in both reactant gases. The results are explained by considering the feasible effects of the treatments on the textural characteristics and on the chemical surface of the coal.Increasing interest in coal gasification processes has led to a need for the investigation of the behaviour of local coal sources in these processes. It is not possible to predict with confidence the gasification behaviour of one coal on the basis of data obtained for another [ 1], because the reactivity depends not only on the coal quality [2], but also on other factors, such as the presence of catalytic inorganic impurities [3]. A high mineral matter content is a characteristic of Spanish coals, which have me,an ash contents in the range 30-45% [4]. It cannot be assumed that the properties of these coals are the same as of coals of similar quality. It might be expected that devolatilization, demineralization and catalytic effects upon reactivity will be modified by the presence of large proportions of mineral matter [5].The behaviour of Spanish coals in gasification reactions has not been studied sufficiently. The carbon-oxygen [air] reaction is important in the overall gasification scheme because the reaction is rapid and exothermic. Moreover, some chars are reacted with air to produce the heat and temperature required to drive the carbonwater reaction for the production of CO and hydrogen.