Summary of the invention
The object of the invention is for the problems referred to above, provide a kind of coal-fired boiler in thermal power plant smoke discharging residual heat to reclaim and reduce discharging comprehensive application system.
Object of the present invention realizes by following technical proposals:
A kind of coal-fired boiler in thermal power plant smoke discharging residual heat reclaims and reduces discharging comprehensive application system, the flow direction along flue gas, on pipeline between from boiler to chimney, be disposed with air preheater, the first low-level (stack-gas) economizer, low cold precipitator, air-introduced machine, the second low-level (stack-gas) economizer, desulfurization island, flue gas is after described the first low-level (stack-gas) economizer cooling, described low cold precipitator entrance flue gas temperature is lower than flue gas dew point temperature, described air preheater import respectively with a cold wind pipeline, cold Secondary Air pipeline is connected, described cold Secondary Air pipeline is provided with Secondary Air steam air heater, described Secondary Air steam air heater is communicated with the second low-level (stack-gas) economizer by hydrophily pipeline, described hydrophily pipeline is provided with expansion tank, water pump.
As optimal way, a described cold wind pipeline is provided with wind steam air heater one time, and a described wind steam air heater and described Secondary Air steam air heater share identical hydrophily pipeline.
As optimal way, a described cold wind pipeline is provided with wind steam air heater one time, and a described wind steam air heater is connected with the low-pressure heater from heat regenerative system by condensing water conduit, and described condensing water conduit is provided with booster.
Workflow of the present invention: flue gas from air preheater out, through the first low-level (stack-gas) economizer, cigarette temperature drop to 90 ℃-100 ℃ of left and right, low-temperature flue gas enters deduster dedusting, then after boosting, air-introduced machine enters the second low-level (stack-gas) economizer, cigarette temperature drop allows inlet temperature to desulfurization, and flue gas enters atmosphere finally by desulfurization island, chimney.The first low-level (stack-gas) economizer is used for heat-setting water, and the second low-level (stack-gas) economizer is by the be situated between cold Secondary Air of heating air preheater import of the hydrophily on hydrophily pipeline.Different according to a cold wind mode of heating of air preheater import, comprise three schemes:
1. the cold wind of air preheater import does not heat,
2. the cold elegance of the air preheater import heating source identical with cold Secondary Air;
3. independent condensate water heating for the cold elegance of air preheater import, this condensate water is from heat regenerative system certain one-level low-pressure heater wherein, with the condensate water in the first low-level (stack-gas) economizer be not from same one-level low-pressure heater.
The effect of (1) first low-level (stack-gas) economizer is as follows:
The first low-level (stack-gas) economizer utilizes fume afterheat heat-setting water, can reduce unit hear rate, reduces the coal consumption of unit generation mark.On the other hand, flue gas is after the first low-level (stack-gas) economizer, and cigarette temperature significantly reduces, and the flue gas volume flow in deduster and downstream greatly reduces, this not only can reduce deduster, air-introduced machine, flue equal-specification capacity, and is conducive to reduce the energy consumption of deduster, air-introduced machine; Meanwhile, cigarette temperature drop is low, can change exhaust gas dust characteristic, electric cleaner is gathered dust favourable.
The first low-level (stack-gas) economizer is arranged in before deduster, and in high ash-laden gas environment, exit gas temperature approaches flue gas dew point temperature, therefore, should take measures to prevent the first low-level (stack-gas) economizer dust stratification, corrosion and wearing and tearing from aspects such as material, technique, designs.
The effect of (2) second low-level (stack-gas) economizers is as follows:
The many synchronized desulfurings of domestic large-scale unit, denitration at present, part arranges low-level (stack-gas) economizer, makes axes of blower power large, and flue gas temperature rise after air-introduced machine is higher.For 1000MW level unit exhaust gas volumn, when air-introduced machine voltage rise reaches about 8500Pa, cigarette temperature will raise approximately 10 ℃.In order effectively to utilize air-introduced machine temperature rise heat, the second low-level (stack-gas) economizer is set.
The second low-level (stack-gas) economizer utilizes fume afterheat, by the hydrophily on hydrophily pipeline, is situated between and is heated cold Secondary Air and/or a cold wind of air preheater import, improves air preheater EAT.On hydrophily pipeline, expansion tank is set and booster provides hydrophily.For wet desulphurization, flue gas enters desulfurization island after the second low-level (stack-gas) economizer, considers water balance in desulfurization island, and after the second low-level (stack-gas) economizer, flue-gas temperature is taken as desulfurization and allows inlet temperature.For wet desulphurization, main water consumption is that will to spray moisture evaporation used up owing to entering the hot flue gas of desulfurization island, arranges after the second low-level (stack-gas) economizer, and desulfurization island inlet flue gas temperature reduces, and can save desulphurization system water consumption.
(3) effect of low cold precipitator is as follows:
Flue gas is after the first low-level (stack-gas) economizer cooling, and electric cleaner entrance flue gas temperature is lower, is near or below flue gas dew point temperature, and performance of precipitator improves, and this electric cleaner is called low cold precipitator.
The electric cleaner inlet flue gas temperature of the current extensive use of China is many 120 ℃ of left and right, and low cold precipitator inlet flue gas temperature is 90-100 ℃ of left and right, and cigarette temperature declines more.Compare with conventional electric cleaner, adopt low cold precipitator to mainly contain following benefit;
1) cigarette temperature drop is low, and flue gas volume flow reduces, and the flow velocity of flue gas is corresponding reducing also, and in deduster, the time of staying will increase, and electric dust collector can effectively be caught flue dust.10 ℃ of the every reductions of flue-gas temperature, exhaust gas volumn will reduce approximately 6%.
2) the low dust specific resistance that can reduce of cigarette temperature drop is to the optimum efficiency interval of electric precipitation.Rule of thumb, when cigarette temperature drops to 90 ℃ of left and right from 130 ℃ of left and right, dust specific resistance can reduce an order of magnitude.In high specific resistance region, lower than resistance, efficiency of dust collection is higher.
3) cigarette temperature drop is low, and deduster electric field breakdown voltage is improved, and this is favourable to improving efficiency of dust collection.Approximately 10 ℃ of the every reductions of cigarette temperature, electric field breakdown voltage raises approximately 3%.
4) can remove most SO
3, reduce tail flue gas cold end corrosion.Because flue-gas temperature has dropped to below dew-point temperature, dust contained flue gas concentration is higher, and total surface area is very large, for condensing of sulfuric acid mist adhered to the condition that provides good.Generally, grey sulphur ratio is greater than at 100 o'clock, the SO in flue gas
3clearance can reach more than 95%, and this contributes to reduce the cold end corrosion of deduster rear pass, blower fan.
5) efficiency of dust collection is high, and dust emission concentration can reach 20-30mg/Nm
3or lower.When deduster inlet flue gas temperature is 99 ℃, during the two low cold precipitator of chamber four electric field of configuration biserial, dust concentration will be on average lower than 20mg/Nm
3; When deduster inlet temperature is 93 ℃, during the two low cold precipitator of chamber four electric field of configuration biserial, smoke dust discharge concentration minimum is only 7 mg/Nm
3.
As can be seen here, low cold precipitator can improve efficiency of dust collection, can adopt in design less deduster specification, less service area, less number of power sources, lower power consumption, less occupation area of equipment etc.
(4) effect of steam air heater is as follows
For preventing air preheater cold-end air cold end corrosion and stifled ash, and adopt steam air heater or flue gas recirculation, steam air heater generally adopts Steam Heating.
In the application, Secondary Air steam air heater adopts hydrophily Jie to absorb the second low-level (stack-gas) economizer off-gas recovery heat, improves air preheater inlet temperature.It is estimated, when the second low-level (stack-gas) economizer flue gas temperature drop is 18 ℃, second wind cooling air temperature can be improved to approximately 30 ℃.Wind steam air heater adopt the thermal source identical with Secondary Air steam air heater or adopt independent condensate water heat (with the condensate water in the first low-level (stack-gas) economizer be not from same one-level low-pressure heater, need be according to heating-up temperature requirement, select suitable condensate water to pick out a little and backwater point), condensate line need arrange booster for boosting.
Adopt the condensate water in the application to compare with conventional steam steam air heater with hydrophily Jie (from the fume afterheat of the second low-level (stack-gas) economizer) steam air heater, pipe specification can reduce, and high-quality steam can be used for generating electricity, and improves unit hear rate, reduces unit net coal consumption rate.Compare with flue gas recirculation, can reduce pressure fan volume flow, reduce pressure fan energy consumption.
Steam air heater is set, improve as far as possible air preheater entrance wind-warm syndrome, not only can reduce air preheater cold-end air corrosion, the more important thing is, air preheater entrance wind-warm syndrome raises, boiler air preheater outlet exhaust gas temperature can raise, and is that the more fume afterheats of the first low-level (stack-gas) economizer recovery have been created condition.According to estimating boiler factory, when air preheater entrance wind-warm syndrome raises 10 ℃, the flue gas exhaust gas temperature about 6-7 ℃ that can raise.
A cold elegance on air preheater is during with the heating of independent condensate water, and this condensate water is from heat regenerative system one-level low-pressure heater, with the condensate water in the first low-level (stack-gas) economizer be not from same one-level low-pressure heater.
Beneficial effect of the present invention: the application is by low-level (stack-gas) economizer subsection setup, and one section is arranged between air preheater and deduster, is used for heat-setting water; One section is arranged between air-introduced machine and desulfurization island, by hydrophily, be situated between and heat the cold Secondary Air of air preheater import, according to the difference of the cold wind mode of heating of air preheater import, there are three kinds of embodiments, because deduster inlet flue gas temperature is lower, can reduce flue gas volume, reduce dust specific resistance, thereby performance of precipitator is improved, dust emission concentration can be reduced to 20~30mg/Nm
3, the cold Secondary Air of air preheater import utilizes fume afterheat heating, and a cold wind of air preheater import heats by condensate water; The application's maximizing utilizes fume afterheat, not only can reduce unit hear rate, reduces unit net coal consumption rate, also can reduce the equipment energy consumptions such as deduster, air-introduced machine, pressure fan, reduce station service power consumption rate, improve the economy of power plant, save more efficiently energy consumption, be conducive to the construction of low-carbon (LC) society.
The specific embodiment
Below in conjunction with specific embodiments and the drawings, the present invention is further illustrated.
According to a cold wind of air preheater import, whether heat and mode of heating difference, be divided into following three embodiment.
Embodiment 1
As shown in Figure 2, a kind of coal-fired boiler in thermal power plant smoke discharging residual heat reclaims and reduces discharging comprehensive application system, the flow direction along flue gas, on the pipeline between 7 from boiler to chimney, be disposed with air preheater 1, the first low-level (stack-gas) economizer 2, low cold precipitator 3, air-introduced machine 4, the second low-level (stack-gas) economizer 5, desulfurization island 6, described air preheater 1 import respectively with a cold wind pipeline 15, cold Secondary Air pipeline 16 is connected, described cold Secondary Air pipeline 16 is provided with Secondary Air steam air heater 9, described Secondary Air steam air heater 9 is communicated with the second low-level (stack-gas) economizer 5 by hydrophily pipeline 10, described hydrophily pipeline 10 is provided with expansion tank 11, water pump 12.On a described cold wind pipeline 15 without heater.
The workflow of the present embodiment: flue gas C from air preheater out, through the first low-level (stack-gas) economizer, cigarette temperature drop to 90 ℃-100 ℃ of left and right, low-temperature flue gas enters deduster dedusting, then after boosting, air-introduced machine enters the second low-level (stack-gas) economizer, cigarette temperature drop allows inlet temperature to desulfurization, and flue gas enters atmosphere finally by desulfurization island, chimney.The first low-level (stack-gas) economizer is used for heat-setting water, and the second low-level (stack-gas) economizer is by the be situated between cold Secondary Air B of heating air preheater import of the hydrophily on hydrophily pipeline.
Embodiment 2
As shown in Figure 3, a kind of coal-fired boiler in thermal power plant smoke discharging residual heat reclaims and reduces discharging comprehensive application system, the flow direction along flue gas, on the pipeline between 7 from boiler to chimney, be disposed with air preheater 1, the first low-level (stack-gas) economizer 2, low cold precipitator 3, air-introduced machine 4, the second low-level (stack-gas) economizer 5, desulfurization island 6, described air preheater 1 import respectively with a cold wind pipeline 15, cold Secondary Air pipeline 16 is connected, described cold Secondary Air pipeline 16 is provided with Secondary Air steam air heater 9, described Secondary Air steam air heater 9 is communicated with the second low-level (stack-gas) economizer 5 by hydrophily pipeline 10, described hydrophily pipeline 10 is provided with expansion tank 11, water pump 12.A described cold wind pipeline 15 is provided with wind steam air heater 8 one time, and a described wind steam air heater 8 and described Secondary Air steam air heater 9 share identical hydrophily pipeline 10.
The workflow of the present embodiment: flue gas C from air preheater out, through the first low-level (stack-gas) economizer, cigarette temperature drop to 90 ℃-100 ℃ of left and right, low-temperature flue gas enters deduster dedusting, then after boosting, air-introduced machine enters the second low-level (stack-gas) economizer, cigarette temperature drop allows inlet temperature to desulfurization, and flue gas enters atmosphere finally by desulfurization island, chimney.
In the present embodiment, the cold wind A of air preheater import adopts the heating source identical with cold Secondary Air B, wind steam air heater 8 and Secondary Air steam air heater 9 are communicated with common hydrophily pipeline 10, the hydrophily being provided by water pump 12 and expansion tank 11 on hydrophily pipeline 10 is situated between, utilization is from the fume afterheat of the second low-level (stack-gas) economizer, cold Secondary Air and a cold wind of the import of heating air preheater, improve air preheater EAT.
Embodiment 3
As shown in Figure 4, a kind of coal-fired boiler in thermal power plant smoke discharging residual heat reclaims and reduces discharging comprehensive application system, the flow direction along flue gas, on the pipeline between 7 from boiler to chimney, be disposed with air preheater 1, the first low-level (stack-gas) economizer 2, low cold precipitator 3, air-introduced machine 4, the second low-level (stack-gas) economizer 5, desulfurization island 6, described air preheater 1 import respectively with a cold wind pipeline 15, cold Secondary Air pipeline 16 is connected, described cold Secondary Air pipeline 16 is provided with Secondary Air steam air heater 9, described Secondary Air steam air heater 9 is communicated with the second low-level (stack-gas) economizer 5 by hydrophily pipeline 10, described hydrophily pipeline 10 is provided with expansion tank 11, water pump 12.
A described cold wind pipeline 15 is provided with wind steam air heater 8 one time, and a described wind steam air heater 8 is connected with the low-pressure heater from heat regenerative system by condensing water conduit 13, and described condensing water conduit 13 is provided with booster 14.
Workflow of the present invention: flue gas C from air preheater out, through the first low-level (stack-gas) economizer, cigarette temperature drop to 90 ℃-100 ℃ of left and right, low-temperature flue gas enters deduster dedusting, then after boosting, air-introduced machine enters the second low-level (stack-gas) economizer, cigarette temperature drop allows inlet temperature to desulfurization, and flue gas enters atmosphere finally by desulfurization island, chimney.The first low-level (stack-gas) economizer is used for heat-setting water, and the second low-level (stack-gas) economizer is by the be situated between cold Secondary Air B of heating air preheater import of the hydrophily on hydrophily pipeline.The cold wind A of air preheater import adopts independent condensate water G heating, this condensate water is from heat regenerative system certain one-level low-pressure heater wherein, with the condensate water F in the first low-level (stack-gas) economizer be not from same one-level low-pressure heater, need be according to heating-up temperature requirement, select suitable condensate water to pick out a little and backwater point, condensate line need arrange booster for boosting.
The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, all any modifications of doing within the spirit and principles in the present invention, be equal to and replace and improvement etc., within all should being included in protection scope of the present invention.