System and method for low-load denitration of boiler

Abstract

The invention discloses a system and method for a low-load denitration of a boiler. The system comprises a hearth outlet flue, a low-temperature superheater flue, a low-temperature reheater flue, a bypass flue, an economizer flue and a denitration flue. The bypass flue is a bypass of a low-temperature reheater, a low-temperature superheater and an economizer. According to the method, mainly, whenthe smoke temperature of a denitration inlet is too low, some smoke enters the denitration inlet through the bypass flue, thus the smoke temperature of the denitration inlet rises, and thus the denitration system can achieve normal investment under the low-load circumstance of the boiler. The system and the method have environment-friendly and energy-saving effects, adjusting flexibility of a unitcan be improved, the utilization rate of the unit is increased, and economic benefits of the unit are increased.

Description

technical field [0001] The invention belongs to the technical field of thermal power, and in particular relates to a system and method for low-load denitrification of boilers. Background technique [0002] As the whole society pays more and more attention to environmental protection issues, the investment requirements for denitrification system of power plant boilers are also becoming more and more stringent. The boiler denitrification system has a minimum requirement for the inlet flue gas temperature. Below this temperature, on the one hand, the denitrification effect is poor, and on the other hand, the denitrification system is easily blocked, making the boiler unable to operate normally. The currently designed boiler denitrification system has the following problems: [0003] (1) In the case of low boiler load, the flue gas temperature at the denitrification inlet is low, and the denitrification system cannot be put into operation; [0004] (2) At present, thermal powe...

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Problems solved by technology

[0003] (1) In the case of low boiler load, the flue gas temperature at the denitrification inlet is low, and the denitrification system cannot be put into operation;

[0004] (2) At present, thermal power units require deep peak regulation. During the low power consumption period, the load of thermal power units is very low, and the flue gas temperature at the denitrification inlet of many units is lower than the normal input requirements for denitrification;

[0005] (3) The denitrification system is not put into operation, the boiler cannot discharge up to the standard, and the thermal power unit cannot be put into operation, which reduces the annual utilization hours of the unit and directly affects the economic benefits of the power plant;

[0006] (4) In the case of low load, due to the low temperature of the primary air and secondary air, the efficiency of the boiler is low, the combustion is unstable, and oil is needed to support the combustion, which increases the operating cost of the power plant;

[0007] (5) In the case of low load, the steam temperature is too high, which is not conducive to the operation of the steam turbine according to its design curve

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