Development and Investigation of the Advanced Oxy-Fuel Power Plants Equipment Preliminary Design

Reducing emissions of harmful substances in the production of electricity at thermal power plants is an intensive task, which can be solved by switching to semiclosed cycles with oxygen combination of fuel and carbon dioxide working fluid. The main advantage of the promising technology, which is the absence of the danger of the formation of toxic substances and the ease of separation of excess carbon dioxide, is provided by burning hydrocarbons in high purity oxygen. This paper presents the results of developing the new power equipment preliminary design: an oxy-fuel combustion chamber, a cooled carbon dioxide turbine, and a high-temperature regenerator. The results of mathematical simulation of physical processes that occurred in the main power equipment are presented. Special attention is paid to calculations of methane--oxygen mixture combustion kinetics in excess carbon dioxide medium and numerical analysis of the processes in the oxy-fuel combustion chamber with taking into account the need to cool the flame tube. The optimal mass ratio of carbon dioxide in the mixture of solvent with oxygen equal to 0.872 is determined, at which the minimal incomplete combustion of fuel can be achieved. The temperature state of the carbon dioxide turbine first-stage nozzle vane was mathematically simulated. The simulation results confirmed the possibility to ensure a sufficient uniformity degree of the temperature field due to making a number of small-radius cooled channels near the airfoil outer surface. A few configurations of heat transfer surfaces for the plate regenerator of the oxy-fuel power unit are proposed. Flow turbulizers with a cylindrical shape and with a fin-type airfoil, and also both of their design versions with ribs were used. The obtained mathematical simulation results have shown that of all channels considered, at the Reynolds number values up to 78 000, the ones having turbulizers with ribs show the best thermal-hydraulic efficiency, whereas at higher Re number values, channels having turbulizers without ribs show the best performance.