Low-Load Stable Combustion Technology of 600 MW Supercritical Low-Calorific Value Lignite Octagonal Tangentially Fired Boiler

ObjectivesWith the high proportion of new energy generation units connected to the power grid, higher requirements are put forward for the deep peak shaving capacity of traditional thermal power units. However, low-calorific value lignite boilers are difficult to burn stably under low-load conditions, so they need to be optimized and adjusted according to the actual situation.MethodsBy changing the combustion organization to compress the height of the flame center and improve the flame filling degree, combined with optimized operating parameters, stable combustion of the boiler under low-load conditions can be achieved. To predict the stable combustion effect, a comprehensive model of flow, heat transfer, mass transfer and combustion is established to study the combustion characteristics of a 600 MW supercritical low-calorific value lignite octagonal tangentially fired boiler at different loads (from 100% to 35%).ResultsThrough local centralized coal feeding and operating No. 1, 3, 4, 5 and 7 coal mills, the minimum stable combustion load of a 600 MW supercritical octagonal tangentially fired boiler with a moisture content of 50% and a calorific value of 8.85 MJ/kg can reach 35%, and the NOx concentration at the furnace outlet does not change significantly under various loads.ConclusionsOptimizing local centralized coal feeding and coal mill operation modes can solve the problem of difficult stable combustion of low-calorific value lignite boilers under low-load conditions, and improve the deep peak shaving capacity of power plants.