Denitrifying low-NOx circulating fluidized bed boiler and denitrifying low-NOx emission control process

Abstract

The invention relates to denitrifying low-NOx emission control process for a circulating fluidized bed boiler. The denitrifying low-NOx emission control process comprises the following steps that thearea of the evaporating heating surface in the boiler is increased, and the heat absorption capacity of the evaporating heating surface of a boiler furnace is changed; the size of hood small holes ofa wind-distribution plate is adjusted, and the size of slag discharging holes of the wind-distribution plate and the size of hood openings in the surrounding wall surfaces are increased; the inlet velocity and incident angle of an inlet flue of a cyclone separator are adjusted, the circulation area of a riser is adjusted according to the amount of fired coal of the boiler and the efficiency of thecyclone separator, the circulation area and the air volume of material-returning air of a material returning valve are adjusted, the flow rate of materials on the interface of a material returning system is controlled at 90-150kg/s through adjustment, the material circulation of the boiler is increased, and the burning temperature is reduced; and an appropriate amount of low-oxygen flue gas is extracted between a dust remover of the boiler and a draft fan and sent to a primary air inlet or a hot primary air outlet of an air pre-heater, the initial oxygen content of coal combustion is reduced,then the low-oxygen flue gas is fed into a primary air chamber at the bottom of the boiler, and the excess air coefficient of the primary air chamber at the bottom of the boiler is adjusted to be 0.4-0.8.

Description

Technical field [0001] The invention belongs to the technical field of circulating fluidized bed environmental protection transformation, and specifically relates to a denitration low NOx circulating fluidized bed boiler and a denitrification low NOx emission control process. Background technique [0002] China is in a period of industrialization, and energy demand is large. China's resource endowment conditions determine that coal is still the main energy source of China's power industry, and high-sulfur coal with high ash and sulfur content greater than 1% accounts for a larger proportion of coal resources, of which coal with ash content greater than 20% accounts for more than 50%. The coal washing process produces a large amount of gangue, burning during washing, and coal slime needs to be used. Circulating fluidized bed combustion has the advantages of a wide range of fuel applications, low-cost dry combustion desulfurization, and low nitrogen oxide emissions. It is a large-s...

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Problems solved by technology

[0003] At present, the ultra-low NOx denitrification environmental protection transformation of circulating fluidized bed boilers is generally based on SNCR+SCR combined denitrification. Many circulating fluidized bed boilers do not have enough space at the end of the SCR denitrification device catalyst. If the SCR denitrification transformation is carried out, it will cause The input cost is relatively high, and at the same time, the catalytic converter of the SCR denitrification device will be regularly repaired and replaced, which will have a certain impact on the economy of the boiler, and the catalyst using the SCR denitrification device will also produce some heavy metal pollution, which is difficult to deal with

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