Abstract.

Gasification is a well developed route to convert a variety of hydrocarbon feedstocks like coal, lignite, oil distillates, residues and petroleum coke and natural gas into synthesis gas ("syngas'). Syngas is, after gastreating, essentially a mixture of carbon monoxide and hydrogen and can be converted into products like ammonia, urea, methanol, 0x0-alcohols, synthetic distillate fuels and hydrogen in subsequent process units. The common characteristic of these applications is the utilisation of syngas for its chemical composition. Syngas use in integrated gasification combined cycle (IGCC) is a relatively new application and is using the clean syngas for its combustion value. IGCC is characterised by a high efficiency to electric power and superior environmental performance in terms of SO, NO, and particulates emissions and in terms of utilisation of by-products (Elemental Sulphur and slag). It is therefore an excellent way to utilise refinery residues and waste products, coal and other solid feedstocks in a flexible and environmentally friendly manner.

INTRODUCTION

Gasification is a well proven technology for the conversion of a great variety of hydrocarbon feedstocks like coal, lignite, oil distillates, residues and gas into synthesis gasrsyngas '). This syngas, mainly of a mixture of carbon monoxide and hydrogen, can be converted in subsequent process units into products like ammonia, urea, methanol, 0x0-chemicals, town gas and hydrogen. These applications are found on a world-wide scale. The common characteristic of above applications, except for towngas, is the utilisation of syngas for its chemical composition.

Towngas from coal and syngas in integrated gasification combined cycle is utilising the clean syngas for its combustion value. Today biomass gasification in several IGCC units in the 30-50 MWe size is being developed and projects are initiated to use gasification for waste disposal. The most sizeable application of gasification is the Sasol coal gasification unit in South Africa producing liquid transportation fuels, towngas and chemicals. A recent project using low priced natural gas is the Shell Middle Distillate Synthesis plant in Malaysia which converts the syngas after gasification into kerosene, gasoil and wax via Fischer Tropsch synthesis.

The use of (gas fired) gas turbine combined cycle systems for power generation has grown rapidly in industry due to its low cost, high efficiency and demonstrated availability. Acceptance of combined cycle technology together with fuel diversification, longer term supply consideration, increasing costs of conventional clean fuels like oil and gas and high (indigenous) coal reserves stimulated the development of coal gasification in Integrated Coal Gasification Combined

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