Thermodynamic Properties and Phase Relations for Refractory-Slag Reactions in Slagging Coal Gasifiers

摘要

The objective of the present research was to provide the data-base and understanding of the chemical parameters needed for prediction and evaluation of the performance of refractory materials under the conditions prevailing in slagging gasifiers. Testing of refractories under atmospheric conditions closely resembling those of slagging coal gasifiers has established that chromium oxide-containing refractories show particular promise in high-temperature gasification because of their high resistance to slagging attack. Consequently, the high-temperature behavior of chromium in crystalline and liquid oxide/silicate systems has been a main focus of this research project. In addition, studies of other high-temperature materials, mainly ZrO sub 2 in various combinations with other oxide components (e.g., CaO, MgO, Al sub 2 O sub 3 , Cr sub 2 O sub 3 , TiO sub 2 ), have been carried out in order to ascertain the potential and chemical constraints of such materials. The main emphasis in this research has been on equilibrium aspects of high-temperature reactions, supplemented with a relatively small amount of work on kinetic aspects of such reactions. The equilibrium studies may be conveniently divided into two groups, viz., investigations of phase relations in multicomponent refractory-slag model systems, and investigations of thermodynamic properties (activity-composition relations) of individual phases. The main focus of the thermodynamic studies was the determination and interpretation of activity-composition relations of chromium oxide and Al sub 2 O sub 3 in silicate melts of interest in slagging coal gasifiers. This was accomplished mainly by studying the equilibrium between chromium oxide in silicate melts and chromium metal in Pt-Cr alloys in a gas phase of known oxygen pressure. 15 refs., 52 figs. (ERA citation 13:017596)