The first example of coal gasification in a slag bath is discussed by Rummel in the 1959; recently the technique has been applied to other processes such as hot metal smelting reduction in which coal is gasified under slag for performing the iron oxide reduction. Of major concern for the plant operations and lifetime are:
Of particular concern for the environment are the gaseous polluting emissions containing:
The fundamental idea is gasifying coal under slight reducing conditions (slight excess of carbon to oxygen), in order to provide the best conditions for fixing sulphur in slag. The advantages expected by this method are:
It is expected that in the application, the basic technology would require specific adaptation for the use of different coals, and for this it is important to clearly identify the range of coals to be subject to experimentation. This technique should, in principle be able to avoid, or reduce, a series of drawbacks arising in coal gasification in power plants and in coal gasifiers. The paper contains the first results of: basic laboratory work, mathematical modelling of the gasification reactor, and the description and setting up of pilot plant. The basic experimental work consists of:
The developed model assumes that overall gasification can be decomposed into three distinct processes: volatile release and combustion (gas-phase combustion), coal-char combustion (solid phase combustion) and coal-char gasification. The polluting elements, i.e. S and N, present in raw coals, are also included in the reaction scheme. The reaction of S with species contained in the molten slag (mainly in the form of CaO), and the water gas-shift reaction were also considered. Thus, eleven (11) major reactions were chosen to represent the essential features of the gasification process. The Fluent CFD code was used to solve the model equations. A description and the setting up of the pilot plant are also showed in the present paper.