Syngas cooling in IGCC systems

This chapter is dedicated to the systems adopted for cooling the raw syngas, coming from the gasifier, to the temperature level required for an effective removal of various contaminants (ash, sulphur, etc.). A significant fraction of the input heat (feedstock heating value) is handled in the cooling process (15-20%): its proper utilization for power production is a key factor affecting the overall plant efficiency. In addition, relevant equipment such as high-temperature heat exchangers (syngas coolers) are used, greatly influencing the investment cost and the plant availability. The discussion about the impact of the cooling process on the IGCC performance is developed here with reference to three widely different systems for the high-temperature portion of cooling: radiant-convective, gas quench-convective, and water quench. Low-temperature heat recovery and clean syngas heating/dilution are addressed as well.