A kind of SCR denitration device inlet flue gas temperature adjustment system and adjustment method

Abstract

The invention discloses a flue gas temperature adjustment system and adjustment method at the inlet of an SCR denitration device. The system includes: a venturi mixer, the inlet of which is connected to a primary hot air duct or / and a secondary hot air duct, and an injection port of which is connected to a boiler in a boiler. The flue gas outlet of the superheater and / or reheater is connected; its outlet is connected to the inlet of the SCR denitration device; the connecting pipe between the Venturi mixer and the superheater and / or reheater is provided with a valve; the tail of the boiler It is connected to the inlet of the SCR denitration device through the flue. The system uses high-temperature flue gas, which can significantly and effectively increase the inlet flue temperature of the SCR denitrification device in the low-load stage, and even achieve full-load denitrification; and can meet the requirements of reducing the SCR inlet when the flue gas temperature exceeds the upper limit in the ultra-high load stage. flue gas temperature, so as to ensure that the unit's denitration device can work normally in each load section.

Description

technical field [0001] The invention belongs to the technical field of power station boilers, and relates to a flue gas temperature regulation system and regulation method at the inlet of an SCR denitration device. Background technique [0002] The disclosure of information in this Background section is only for enhancement of understanding of the general background of the invention and should not necessarily be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person of ordinary skill in the art. [0003] With the rapid development of my country's national economy and the improvement of people's living standards, while the capacity of major power grids continues to expand, the power consumption structure is also constantly changing. The peak-to-valley difference is increasing day by day, so the problem of peak regulation of the power grid is becoming more and more prominent. At the same time, the power generat...

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Problems solved by technology

[0004] However, deep peak shaving is an unconventional operating condition of the unit. Not only is the economy poor, but the safety is also relatively fragile. The most direct problem is that as the load decreases, the combustion intensity of the boiler decreases, and the flue gas temperature decreases accordingly.

At present, power plant boilers basically use SCR denitrification devices to reduce nitrogen oxides. The catalyst requires the flue gas temperature to be 320-420°C. During the deep peak shaving period, the flue gas temperature drops a lot. Ammonia plant exits, nitrogen oxide emissions exceed standard

In order to solve this problem, the methods currently used are: (1) economizer flue gas bypass technology, this technology has a small investment, but has many disadvantages, such as reducing boiler efficiency, limited improvement, and low failure rate of flue gas baffles. (2) The graded economizer technology has the advantages of better economy and does not reduce the boiler efficiency, but it has a large investment, high space requirements, and old units cannot be changed; (3) The economizer water supply bypass, which This technology generally requires less investment, simple construction, and a small amount of work, but the smoke temperature raising capacity is small, and the economizer has the risk of boiling, which reduces the thermal efficiency of the boiler; (4) Economizer hot water recirculation, this technical system is simple, The temperature increase range is large, but it is only suitable for subcritical forced circulation units. It is necessary to add a high-temperature and high-pressure furnace water circulation pump to reduce the reliability of the boiler and reduce the thermal efficiency of the boiler; Power safety, large investment, the disadvantage is that the range of smoke temperature increase is limited, the steam turbine unit is added with an air extraction port, the transformation is difficult, and the thermal efficiency of the boiler is reduced

From the above analysis, it can be seen that the existing problems in the technical transformation to solve the low flue gas temperature at the inlet of the SCR denitrification device are: technical measures with simple technology and small investment, low reliability of equipment, limited range of raising flue gas temperature, and sacrifice Boiler economy; on the other hand, without sacrificing boiler economy, the obvious technical measures to increase the flue gas temperature require large investment, and the system and equipment are more complicated

[0005] In addition, conventional methods have their own advantages and disadvantages in terms of investment, construction, and effect in terms of adjusting and increasing the smoke temperature at the SCR inlet. Among them, one of the common disadvantages of these existing methods is that the smoke temperature at the SCR inlet needs to be adjusted artificially. , it is necessary to greatly increase the labor intensity of the operating personnel. At the same time, if the operating personnel have many operating tasks and neglect the adjustment and over-adjustment of the SCR inlet smoke temperature, it will cause the SCR ammonia injection device to trip, and the environmental protection indicators will exceed the standard, etc. question

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