Thermodynamic analysis of 12H18N10T steel interaction with coal-air products in coal plasma ignition system

The article considers steel interaction of various steel grades, in particular alloy steels, with atmosphere of solid fuels combustion at thermal power plants. The results of thermodynamic analysis are presented, modeling the interaction of austenitic steel 12X18H10T with carbon and coal in air atmosphere under equilibrium conditions. Thermodynamic calculations for the interaction of alloy steels were modeled using the ASTRA4/PC software package. Calculations were carried out in temperature range from 273 to 1823 K with pressure varying from 1 to 10 atm. By varying the thermodynamic parameters (temperature, pressure), changes in chemical equilibria occurring both in the gas phase and in the condensed state were studied. Thermodynamic modeling showed that the interaction of 12X18N10T steel with coal combustion products, even without taking into account ash content, should cause intense corrosion of fuel thermochemical preparation chamber, the products of which may be oxides, carbides, nitrides and sulfides of alloying elements. Xray phase analysis of the coalair mixture combustion products in the plasma coal ignition system showed the presence of Fe3O4 and Cr2O3 oxides in all the studied samples. Microscopic analysis established that the formation of chromium carbides occurs along grain boundaries and leads to avalanchelike destruction of the walls of fuel thermochemical preparation chamber.