Study On The Influence Of Different Exhaust Gas Nozzle Arrangements To The Combustion Characteristics Of Coal-fired Boiler

In this paper,the influence of the location of the exhaust gas nozzle in the combustion process in the furnace is studied.This paper adopts the FLUENT software and carries out a numerical simulation of 3 alternative combustion systems in furnace combustion process of a supercritical front-rear wall opposed firing boiler 350 MW firing lean coal.?Boiler type: B&WB-1098/25.4-M?.Except the location of exhaust gas nozzles,the other conditions are all the same in these 3 alternatives.Regarding these 3 alternative combustion systems,the numerically simulation were carried out respectively to research the flow,combustion and the distributions of physical parameters under full load conditions?condition 1,condition 2 & condition 3?and under medium low load conditions?condition 4 and condition 5?.By comparing the calculated results,the optimal scheme is selected.It studiedThrough the comparisons of velocity fields,temperature fields and component fields?O₂,CO & CO₂?of these three full load conditions,we found that the physical quantities of condition 3 are optimal.At the same time,after comparing the 3 conditions stimulation results with the thermodynamic calculation value,we also found the temperature deviation of case 3 is the minimum.Therefore we can determine that case 3 is the best scheme and can be considered as the final solution for the boiler combustion system.Also according to the best scheme,we carried out the numerical simulation under medium condition and low load condition,after comparing the results with that under the full load,we found although there is a certain deviation of the velocity field,temperature field,O₂ and CO₂ concentration value between under the low load condition and under the full load condition,burning effect is worse than that under full load,the results can satisfy the parameters requirements under medium condition and low load condition,further prove the feasibility of the best scheme selected in this paper.The research results of this paper have been applied in the design of the boiler.At present,the design and manufacture of the boiler have been completed,and the installation is close to completion.In this paper,the simulation calculation simulates the real operating state in the furnace,and provides an important reference for the optimization design of the boiler combustion system.The data simulation work in this paper not only offers an important reference value to understand the optimal design of large boiler and the future economic safe operation,but also enriches the boiler research content at the same time.