Method and system capable of improving coal fired boiler low load SCR inlet smoke temperature

Abstract

The invention discloses a method and system capable of improving coal fired boiler low load SCR inlet smoke temperature. The adopted method comprises the steps that fire coal of a tangential firing oropposed firing boiler is sprayed into a hearth to be combusted with a layer as a unit, the laminated coal amount of each combustor is gradually increased from low to high in the hearth height direction, and a positive V distribution is formed; secondary air amount of each combustor is gradually reduced from low to high in the hearth height direction, and inverted V distribution is formed; meanwhile, the adjustable shrinkage opening degree of a pulverized coal pipe, and the secondary air valve opening degrees or secondary air blade angles of the combustors are controlled, and the coal amount and the secondary air amount put into the combustors on a combustor layer can meet the target coal amount and the target secondary air amount. Through adjusting the coal amount and the secondary air amount distribution put into the combustors of the combustor layer, on the premise of reducing the hearth outlet NOX content and baring powder coal burn-out rate influences, the low-load SCR inlet smoketemperature is effectively improved.

Description

technical field [0001] The invention belongs to the technical field of power plant boilers, in particular to a method and system for increasing the smoke temperature at the inlet of a low-load SCR of a coal-fired boiler. Background technique [0002] With the acceleration of my country's energy structure adjustment, clean energy has entered a new stage of large-scale development. Large-scale grid integration of renewable energy such as hydropower, wind power, and photovoltaics has increased the peak-to-valley difference in the power grid system. Under the condition of relatively insufficient peak resources, it is inevitable for coal-fired thermal power units to perform deep low-load peak-shaving operation and have as fast as possible load regulation performance. [0003] Coal-fired thermal power units’ deep peak-shaving and low-load operation capabilities are limited by many aspects. The stable operation capability of the Selective Catalytic Reduction (SCR) system is one of t...

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Problems solved by technology

[0003] Coal-fired thermal power units’ deep peak-shaving and low-load operation capabilities are limited by many aspects. The stable operation capability of the Selective Catalytic Reduction (SCR) system is one of the important indicators to consider whether the unit has deep peak-shaving capabilities. The existing technology is When the coal-fired thermal power unit is in low-load operation, each burner layer in operation often adopts the combustion method of equal coal and air distribution. Due to the structure of the secondary air box of the counter-fired boiler, there is an air volume distribution of each burner in the burner layer in operation. The problem of unevenness, when the load is low, the flue gas temperature at the SCR inlet is low and the flue gas temperature deviation is large, which affects the stable operation of the SCR system, which undoubtedly limits the deep peak-shaving and low-load operation capacity of coal-fired thermal power units

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