Experimental Research On Concretion Characteristics Of High Temperature Syngas In Integrated Gasification Combined Cycle System

Integrated gasification combined cycle is one of the trends of clean coal power generation technology. However, alkali vapors easily deposit on heat exchanger surfaces and will lead to slagging. Furthermore, it will also cause high-temperature corrosion of gas turbine blades. Although tolerance limit of alkali vapors in the flue gas is usually given under 0.024 ppm by weight at the inlet of gas turbines, it is actually one or more orders of magnitude than that of the limit. Research on the concretion characteristics of alkali metal, will play an important role in the development of integrated gasification combined cycle.In this paper, an experimental facility was built to study the concretion characteristics of high temperature syngas in the integrated gasification combined cycle. A separable tubular exchanger was designed and built at the outlet of the simulating syngas producing stove to collect the concreted alkali metal, where the simulating syngas is the mixture of CO, CO2, N2 and H2O. By adjusting the contents of the main syngas components, the effects of syngas and alkali metal components on the concretion process were obtained. The concreted components and the concreting state were further analyzed using XRD and SEM. The concretion mechanism on the alkali metal was discussed finally.By analysis, the following conclusions were discovered: the concreted temperature of alkali metal is between 620-655℃in the reducing atmosphere; the steam has no effect on this concreted temperature; the lower the concentration of CO in the syngas, the higher the concreted temperature; if the concentration of CO and the proportion of Na+ and K+ keep invariable, the concreted temperature when both Cl- and SO42- exist is lower than the case when only Cl- exists; the temperature will become higher if the proportion of Na+ become higher when the alkali metal contains both Cl- and SO42- in the same concentration of CO; the result of SEM analysis shows the coagulation surface is complicated, which contains both crystal and non-crystal; the result of XRD analysis shows most of the crystal is NaCl in the coagulation; 600℃maybe the suitable temperature for the syngas come into the convective syngas cooler.