Economizer improving SCR commissioning rate under low load working condition

Abstract

The invention discloses an economizer improving the SCR commissioning rate under the low load working condition. A water supply pipeline of an inlet of the economizer is provided with a by-pass. A by-pass pipeline is connected with a middle header of the economizer. The by-pass is sequentially provided with a one-way valve, a throttling valve and a flow adjusting valve in the medium flowing direction. According to the economizer, the opening degree of a by-pass valve is adjusted under the low load condition so as to reduce medium flow between an inlet header and the middle header of the economizer in a boiler, the heat output of the smoke side of the economizer can be reduced, the smoke temperature of an outlet of the economizer rises, and the commissioning rate of a power plant SCR under the low load condition can be effectively improved; the catalyst activity of the SCR is promoted due to rising of the temperature of an SCR system, the SCR system obtains the higher denitration capacity, and therefore a power plant can meet the environmental protection index requirement better over a much longer time period.

Description

technical field [0001] The invention relates to the field of flue gas denitrification of power station boilers, in particular to an economizer which improves the commissioning rate of SCR under low-load working conditions. Background technique [0002] Selective catalytic reduction (SCR) is currently the most mature denitrification technology in industry. This technology is mainly used in thermal power plants, motor vehicles, ships and other fields. Its main function is to remove nitrogen oxides produced by boiler or engine combustion. NO accounts for about 95% of nitrogen oxides, NO 2 It accounts for about 5%, and also contains a small amount of N 2 O, these gases are discharged into the atmosphere, causing acid rain, photochemical smog, ozone layer depletion and other hazards. my country's main energy source comes from coal combustion. According to statistics, 67% of my country's nitrogen oxide emissions come from coal combustion, and thermal power plants account for 50...

AI Technical Summary

Problems solved by technology

However, power plant boilers cannot operate at high load for a long time. During the off-peak period of electricity consumption, the power grid’s demand for power generation load of the power plant is low, and the power plant boiler operates under low load. At this time, the reaction temperature of the flue gas in the SCR system is low. The activity decreases with the decrease of temperature, so the denitrification efficiency is also low

In addition, when the flue gas temperature at the inlet of the denitrification device does not reach the lower limit of the operating temperature of the denitrification system, the denitrification system will stop operating, and the emission of nitrogen oxides will increase, making it difficult for the power station to meet the environmental protection indicators stipulated by the state.

On the other hand, although the catalyst stops working, it is still being washed by the flue gas, and the wear of the catalyst by the fly ash does not decrease, resulting in a reduction in the service life of the catalyst

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