Improve the structure of coal-burning boiler tail flue gas denitration devoting rate
Technical field
The relevant energy-saving and emission-reduction of the utility model field, particularly a kind of structure that there is important function to improving coal-fired unit SCR denitrogenation devoting rate.
Background technology
China's energy resource structure be take coal as main, and in Technology of Electrical Power Generation, coal-fired unit occupies main share.At present, China's coal burning machine kludge has approached 80%, surpasses nearly 40 percentage points of world average level.In the coal resources upstream, because Coal Quality can not get paying attention to, downstream often occurs that coal quality changes greatly, causes boiler coke, undercapacity, even pollutant emission exceeds standard.Especially aspect pollutant emission, under the appearance of a series of policies and regulations of country (especially " fossil-fuel power plant atmospheric pollutant emission standard 2011 "), electricity power enterprise continues to increase under pressure, even the environmental protection equipment design is qualified, but under the condition of extraneous ature of coal fluctuation, the pollutant removing condition can not meet, and causes pollutant to exceed standard.
For NOx removes, at coal type change, particularly, in the performing low-load running of machine set situation, SCR reactor inlet flue-gas temperature is on the low side, has a strong impact on the denitration devoting rate.The cardinal principle of SCR denitride technology is, ammonia is reacted with nitrogen oxide, generates nitrogen and water, and precondition is to have catalyst (as vanadic anhydride) and rational reaction temperature (300 ℃~420 ℃).But due to the ature of coal reason, often occur the too low situation of temperature in the SCR reactor, and some unit, for a long time in the underrun state, causes and can't normally spray ammonia at present, has a strong impact on denitration efficiency.Part electricity power enterprise, for improving denitration efficiency, adopts the method that strengthens the ammonia amount, has not only increased the denitrogenation cost, and may cause ammonia leakage, causes secondary pollution.
The utility model content
The technical problem that the utility model solves is providing a kind of structure that can improve the SCR reactor inlet temperature, practical operation situation according to unit, reasonable approach is for improving the SCR reactor inlet temperature the most, the raising of flue-gas temperature also is conducive to the operation of downstream air preheater, to improving first and second air temperature, prevent that the air preheater cold end corrosion from having played certain effect.
The technological means that the utility model adopts is: a kind of structure that improves coal-burning boiler tail flue gas denitration devoting rate, it comprises SCR reactor and SCR upstream heat exchanger, be provided with by-pass flue between second gas approach of in the first gas approach and the heat exchange of SCR upstream of SCR reactor, answering device, this by-pass flue is provided with controllable register.
The beneficial effect that the utility model produces is as follows: the present invention introduces the SCR reactor inlet by the high temperature position flue gas, can effectively improve SCR inside reactor temperature, can effectively guarantee that SCR reactor inlet flue-gas temperature is within best reduction temperature scope, thereby improve the denitrogenation devoting rate.The utility model is simple in structure, cheap, can in numerous coal fired power plants, promoted.
In addition, the present invention also possesses following advantage.
(1) the present invention only need be installed by-pass flue additional at SCR entrance pipeline section place and its heat transmission equipment entrance pipeline section place, upstream, and remodeling method is simple, and with low cost.
(2) the present invention is in actual moving process, and the valve that only needs to regulate on by-pass flue can conveniently be controlled the SCR inlet temperature, simple and easy to do.
(3) the present invention also is conducive to optimization downstream, downstream air preheater operating condition, and then improves whole boiler efficiency.
(4) the present invention has certain coordinative role to the heat distribution of boiler part heat transmission equipment.
The accompanying drawing explanation
Fig. 1 is structural representation of the present utility model.
The specific embodiment
As shown in Figure 1, a kind of structure that improves coal-burning boiler tail flue gas denitration devoting rate, it comprises SCR reactor 4 and SCR upstream heat exchanger 3, be provided with by-pass flue 1 between second gas approach 31 of in the first gas approach 41 and the heat exchange of SCR upstream of SCR reactor 4, answering device 3, this by-pass flue 1 is provided with controllable register 2.
In the situation that in the first gas approach 41 of SCR reactor 4, flue-gas temperature is on the low side, by regulating the controllable register 2 on by-pass flue 1, the flue gas of the second gas approach 31 positions of upstream heat exchanger 3 can be imported, rationally to control the high-temperature flue gas flow, improve the catalytic reduction reaction temperature, and then improve the denitrogenation devoting rate.Wherein, this upstream heat exchanger 3 can be generally low-level (stack-gas) economizer, superheater or reheater etc.