Modeling of Filtration Combustion of Carbon

The kinetics of the overall reactions of carbon gasification at temperatures up to 1600 K is studied. The kinetic characteristics of the reactions are taken into account in a distributed mathematical model of filtration combustion of carbon. By computational experiment at different values of process control parameters (the gas flow rate, the fraction of the oxidant in the gas, and the mass ratio of carbon to the inert material in the combustible mixture), it is found that, in the wave of filtration combustion of carbon under superadiabatic conditions, carbon gasification can predominately yield either CO₂ or CO.     

Model for filtration combustion of carbon: Approximation of a thermodynamically equilibrium composition of combustion products

A model for stationary filtration combustion of mixtures of carbon with a solid incombustible material in a counterflow a gas containing oxygen and a chemically inert gas is proposed. If the rates of chemical reactions in the combustion zone are sufficiently high, the ratio of carbon monoxide and dioxide in combustion products is assumed to be thermodynamically equilibrium at the combustion temperature. This assumption provides a closure for the balance equations for carbon, oxygen, and energy in the combustion front and gives explicit analytical expressions for the combustion temperature and composition of the products as functions of the composition of the carbon/inert mixture and of the gaseous oxidizer in stoichiometric regimes. Combustion modes are numerically calculated for a wide variation of the compositions. The upper limit of the reagent supply rate until which equilibrium relations can be used is found. A comparison of model predictions with experimental results shows their reasonable qualitative agreement.     

Stability of Calcium Chloride in the Air–Steam Gasification of Solid Fuel in Filtration Mode

The emission of HCl from calcium chloride during the air–steam gasification of solid fuel in the filtration combustion mode was studied. The limiting amounts of HCl released into the gas phase under real conditions of a shaft kiln gasifier were estimated. It was shown that the most important factors responsible for the stability of CaCl₂ are the humidity of an oxidant gas and the process temperature.     

HCl Neutralization by Alkaline Sorbents in the Gasification of Chloride-Containing Fuel in the Filtration Combustion Mode

In this paper, we have studied the patterns of the HCl absorption by calcium-containing sorbents under countercurrent gasification in the filtration combustion mode. Experiments have been performed in a vertical batch reactor at temperatures of up to 1200°C. The following sorbents have been employed: calcium oxide and calcium carbonate (in the form of chalk and marble). The efficiency of HCl absorption by sorbents has been estimated. The completeness of HCl uptake has been shown to be limited by partial hydrolysis of the calcium chloride formed in the high-temperature zone.     

Characteristics of the Air–Steam Gasification of Carbonaceous Fuels by Filtration Combustion at an Elevated Pressure

Theoretical Foundations of Chemical Engineering - Calculation results on the stationary mode of the filtration combustion of carbon mixtures with a solid incombustible material in a counterflow of...