Alkali removal at about 1400 °C for the pressurized pulverized coal combustion combined cycle.: 2.: Sorbents and sorption mechanisms

The limitation of fossil fuel resources and the necessity of reducing CO2 emission requires an increase in the efficiency of power plants by using combined cycle power systems. Pressurized pulverized coal combustion (PPCC) is a potential method to realize these objectives. The direct use of hot flue gas for driving a gas turbine requires a hot gas cleanup to prevent corrosion of the turbine blading. One of the main problems is the alkali release during the coal combustion process. This investigation was conducted to find suitable sorbent materials for alkali removal at 1400 degrees C under PPCC conditions sufficient to fulfill the demands of the gas turbine manufacturers. An alkali chloride-laden gas stream was passed through a bed of aluminosilicate sorbents using a flow channel reactor. Qualitative and quantitative analysis of the hot gas downstream of the sorbent bed was carried out using high-pressure mass spectrometry (HPMS). The results were used to estimate, by means of thermodynamic calculations, the risk of hot corrosion in a gas turbine. The mechanism of the sorption process has been investigated.