CN103846007A - Denitration control method of flue-gas selective catalytic reduction device - Google Patents
Denitration control method of flue-gas selective catalytic reduction device Download PDFInfo
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- CN103846007A CN103846007A CN201410096901.5A CN201410096901A CN103846007A CN 103846007 A CN103846007 A CN 103846007A CN 201410096901 A CN201410096901 A CN 201410096901A CN 103846007 A CN103846007 A CN 103846007A
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Abstract
The invention relates to a denitration control method of a flue-gas selective catalytic reduction device. The denitration control method is characterized in that by utilization of the property of in-series connection of a front heated surface and a rear heated surface of an SCR (Selective Catalytic Reduction) device, a bypass pipeline is connected beside a working medium for connecting a heated surface behind the SCR device and a heated surface before the SCR device; an inlet of the bypass pipeline is connected with a working-medium outlet pipeline of the heated surface behind the SCR device, and an outlet of the bypass pipeline is connected with a working-medium outlet pipeline of the heated surface before the SCR device, and a bypass adjusting valve is arranged on the bypass pipeline, so that the working medium at the outlet of the heated surface behind the SCR device is partially or wholly in direct short-circuit to the outlet pipeline of the heated surface before the SCR device. The denitration control method has the advantages that the heat absorbing amount of the heated surface before the SCR device is reduced, the temperature of flue gas before an inlet before the SCR device is increased and the problem that the temperature of the flue gas at the inlet when a boiler part operates with loads is solved.
Description
Technical field
The present invention relates to a kind of pulverized-coal fired boiler with flue gas selective catalytic reduction device (SCR), particularly relate to the denitration control method of flue gas selective catalytic reduction device in a kind of pulverized-coal fired boiler.
Background technology
In process of coal combustion in pulverized-coal fired boiler, can inevitably produce nitrogen oxide (NOx), level that sometimes can not meet the requirement of environmental protection, therefore needs to arrange flue gas selective catalytic reduction device (SCR).Current SCR matching requirements range of reaction temperature is narrow, generally within the scope of 320～400 DEG C, thereby SCR device need to be arranged between boiler heating surface in 320～400 DEG C of cigarette warm areas.
In the time moving under combustion apparatus sub-load, the flue-gas temperature of cigarette warm area will be lower than the temperature range requiring, and can cause like this denitration efficiency of SCR device sharply to reduce.For this reason, conventionally adopt the method for flue gas short circuit, before part high-temperature flue gas is directly passed into SCR device, control the ratio of normal flue gas flow and short circuit flue gas flow, to adjust the flue-gas temperature that enters SCR device.High-temperature flue gas can, to drawing between the heating surface of flow through shaft, also can be drawn from reversal chamber, but because the mechanical performance of gas baffle under high temperature is not good, adjusting function is very poor, easily malfunctioning after operation a period of time, therefore, the adjusting of high-temperature flue gas is more difficult.
For this reason, people have explored under combustion apparatus sub-load and have maintained the SCR device inlet temperature method within the scope of 320～400 DEG C substantially, are wherein to improve the SCR device inlet temperature of heating surface before compared with effective method.As in the time that the heating surface before of SCR device on large-sized boiler is economizer, by changing the method for therrmodynamic system operational factor, under underload, strengthen the heat that adds of high-pressure heater, improve the water temperature of economizer import, reduce heat transfer temperature difference, thereby effectively improved the temperature of SCR device import flue gas.The problem of this way is the operating condition that has changed steam turbine, has strengthened the high steam amount of drawing gas, and has reduced cycle efficieny.
Summary of the invention
The object of this invention is to provide a kind of denitration control method of flue gas selective catalytic reduction device, not affect under the prerequisite of unit efficiency, guarantee that under underrun, SCR device still reaches higher denitration efficiency.
The denitration control method of flue gas selective catalytic reduction device provided by the invention is by the working medium pipeline between heating surface and heating surface before SCR device, to be connected a bypass duct connecting after SCR device, the import of described bypass duct connects the SCR device sender property outlet pipeline of heating surface afterwards, outlet is connected with the sender property outlet pipeline of heating surface before SCR device, and bypass valve is set on bypass duct, with by part or all direct short-circuit of heating surface outlet working medium after SCR device to the sender property outlet pipeline of heating surface before SCR device.
Denitration control method of the present invention has been utilized the character of SCR device front and back heating surface working medium series connection, by part or all direct short-circuit of heating surface outlet working medium after SCR device to the sender property outlet pipeline of heating surface before SCR device, make to enter less or do not enter into SCR device heating surface before by the working medium of heating surface after SCR device, reduce the SCR device caloric receptivity of heating surface before with this, improve SCR device import flue-gas temperature before, while having solved combustion apparatus operation at part load, the problem that its input gas temperature is on the low side.
Wherein, before and after described SCR device, the heating surface of series connection can be economizer, can be also air preheater, can also be heating surface individualism before SCR device, there is no heating surface after SCR device.
No matter before SCR device, heating surface is economizer or air preheater, even working medium flow is 0 in heating surface, directly dry combustion method under the flue-gas temperature below 400 DEG C of heating surface, also in the allowed band of carbon steel material.Therefore, can to regulate arbitrarily short circuit working medium flow in bypass duct be working medium flow 0 to 100%.
Due to the denitration control method of flue gas selective catalytic reduction device of the present invention regulate to as if cryogenic fluid, for the cycle efficieny of pulverized-coal fired boiler without any impact, simultaneously, use the inventive method to regulate and control to have and regulate advantage sensitive, reliable, easy to maintenance, and the security of heating surface is without any problem.
Brief description of the drawings
Fig. 1 be before and after the flue gas selective catalytic reduction device denitration control method flow chart of heating surface while being economizer.
Fig. 2 is the denitration control curve that economizer short circuit regulates flue gas selective catalytic reduction device.
Fig. 3 be before and after the flue gas selective catalytic reduction device denitration control method flow chart of heating surface while being air preheater.
Fig. 4 is the denitration control curve that air preheater short circuit regulates flue gas selective catalytic reduction device.
Flue gas selective catalytic reduction device denitration control method flow chart when Fig. 5 is single-stage heating surface.
Fig. 6 is the denitration control curve that the short circuit of single-stage heating surface regulates flue gas selective catalytic reduction device.
Detailed description of the invention
Below in conjunction with the drawings and specific embodiments, the present invention is conducted further description.
The structure of flue gas selective catalytic reduction device as shown in Figure 1, after being arranged on the reversal chamber 1 of pulverized-coal fired boiler, is furnished with high-temperature air preheater 13, high-temperature economizer 12, SCR device 3, low-level (stack-gas) economizer 4 and low-temperature air preheater 5 successively.High-temperature flue gas turns to descending through reversal chamber 1, pass through successively high-temperature air preheater 13 and high-temperature economizer 12, draw from the cigarette warm area of 320～400 DEG C of high-temperature economizer 12 belows, after uptake flue 2 is up, turn down again, enter in SCR device 3, in uptake flue 2, spray into the ammonia that denitration is used, up turning by flue gas, descending and current-sharing baffle plate is set realizes evenly and mixing, in SCR device 3, under the effect of catalyst, complete after denitration reaction, flue gas is discharged through low-level (stack-gas) economizer 4 and low-temperature air preheater 5.
The sender property outlet pipeline 7 of low-level (stack-gas) economizer 4 is communicated with the working medium inlet pipeline 8 of high-temperature economizer 12, and the sender property outlet pipeline 11 of high-temperature economizer 12 connects drum inlet tube 14.Feedwater is after low-level (stack-gas) economizer 4 working medium inlet pipelines 6 enter low-level (stack-gas) economizer 4 heating, the rear outflow of high-temperature economizer 12 of flowing through, and causes drum through drum inlet tube 14.Between low-level (stack-gas) economizer 4 sender property outlet pipelines 7 and high-temperature economizer 12 sender property outlet pipelines 11, bypass duct 9 is set, and on bypass duct 9, bypass valve 10 is installed.Regulate the aperture of bypass valve 10, the feedwater of part after low-level (stack-gas) economizer 4 heating do not entered in high-temperature economizer 12, directly introduce drum inlet tube 14.In the time entering the discharge reduction of high-temperature economizer, the water temperature of high-temperature economizer outlet improves, thereby has reduced the heat transfer temperature difference of high-temperature economizer, and high-temperature economizer heat output declines, flue gas reduces through the temperature drop of high-temperature economizer, and the flue-gas temperature that enters SCR device improves.Therefore,, by regulating the aperture of bypass valve 10, regulate the discharge that enters high-temperature economizer 12, to regulate the temperature that enters SCR device 3 flue gases.Its adjustment curve is shown in Fig. 2.
The structure of flue gas selective catalytic reduction device is identical with embodiment 1, as shown in Figure 2, after being arranged on the reversal chamber 1 of pulverized-coal fired boiler, be furnished with successively high-temperature air preheater 13, high-temperature economizer 12, SCR device 3, low-level (stack-gas) economizer 4 and low-temperature air preheater 5.High-temperature flue gas turns to descending through reversal chamber 1, pass through successively high-temperature air preheater 13 and high-temperature economizer 12, draw from the cigarette warm area of 320～400 DEG C of high-temperature economizer 12 belows, after uptake flue 2 is up, turn down again, enter in SCR device 3, in uptake flue 2, spray into the ammonia that denitration is used, up turning by flue gas, descending and current-sharing baffle plate is set realizes evenly and mixing, in SCR device 3, under the effect of catalyst, complete after denitration reaction, flue gas is discharged through low-level (stack-gas) economizer 4 and low-temperature air preheater 5.
The sender property outlet pipeline 7 of low-temperature air preheater 5 is communicated with the working medium inlet pipeline 8 of high-temperature air preheater 13, and the sender property outlet pipeline 11 of high-temperature air preheater 13 connects hot air duct 15., after low-temperature air preheater 5 working medium inlet pipelines 6 enter low-temperature air preheater 5 heating, introduce high-temperature air preheater 13, then send into hot air duct 15 from the air of blower fan.Between low-temperature air preheater 5 sender property outlet pipelines 7 and high-temperature air preheater 13 sender property outlet pipelines 11, bypass duct 9 is set, and on bypass duct 9, bypass valve 10 is installed.Regulate the aperture of bypass valve 10, the hot-air of part after low-temperature air preheater 5 heating do not entered in high-temperature air preheater 13, direct short-circuit is to hot air duct 15.In the time entering the air mass flow reduction of high-temperature air preheater, the temperature of high-temperature air preheater outlet improves, thereby reduce the heat transfer temperature difference of high-temperature air preheater, high-temperature air preheater heat output declines, flue gas reduces through the temperature drop of high-temperature air preheater, and the flue-gas temperature that enters SCR device improves.Therefore,, by regulating the aperture of bypass valve 10, regulate the air mass flow that enters high-temperature air preheater 13, to regulate the temperature that enters SCR device 3 flue gases.Its adjustment curve is shown in Fig. 4.
The structure of flue gas selective catalytic reduction device as shown in Figure 5, after being arranged on the reversal chamber 1 of pulverized-coal fired boiler, is furnished with high-temperature air preheater 13, high-temperature economizer 12, SCR device 3 and low-temperature air preheater 5 successively.High-temperature flue gas turns to descending through reversal chamber 1, pass through successively high-temperature air preheater 13 and high-temperature economizer 12, draw from the cigarette warm area of 320～400 DEG C of high-temperature economizer 12 belows, after uptake flue 2 is up, turn down again, enter in SCR device 3, in uptake flue 2, spray into the ammonia that denitration is used, up turning by flue gas, descending and current-sharing baffle plate is set realizes evenly and mixing, in SCR device 3, under the effect of catalyst, complete after denitration reaction, flue gas is discharged through low-temperature air preheater 5.
Feedwater is communicated with the working medium inlet pipeline 8 of high-temperature economizer 12, the sender property outlet pipeline 11 of high-temperature economizer 12 connects drum inlet tube 14, between feedwater and high-temperature economizer 12 sender property outlet pipelines 11, bypass duct 9 is set simultaneously, and on bypass duct 9, bypass valve 10 is installed.Feedwater flow flows out after high-temperature economizer 12, causes drum through drum inlet tube 14.Regulate the aperture of bypass valve 10, part feedwater is not entered in high-temperature economizer 12, directly introduce drum inlet tube 14.In the time entering the discharge reduction of high-temperature economizer, the water temperature of high-temperature economizer outlet improves, thereby has reduced the heat transfer temperature difference of high-temperature economizer, and high-temperature economizer heat output declines, flue gas reduces through the temperature drop of high-temperature economizer, and the flue-gas temperature that enters SCR device improves.Therefore,, by regulating the aperture of bypass valve 10, regulate the discharge that enters high-temperature economizer 12, to regulate the temperature that enters SCR device 3 flue gases.Its adjustment curve is shown in Fig. 6.
Claims (4)
1. the denitration control method of a flue gas selective catalytic reduction device, by the working medium pipeline between heating surface and heating surface before SCR device, to be connected a bypass duct connecting after SCR device, the import of described bypass duct connects the SCR device sender property outlet pipeline of heating surface afterwards, outlet is connected with the sender property outlet pipeline of heating surface before SCR device, and bypass valve is set on bypass duct, with by part or all direct short-circuit of heating surface outlet working medium after SCR device to the sender property outlet pipeline of heating surface before SCR device.
2. the denitration control method of flue gas selective catalytic reduction device according to claim 1, is characterized in that the heating surface of connecting before and after described SCR device is economizer or air preheater.
3. the denitration control method of flue gas selective catalytic reduction device according to claim 1 and 2, is characterized in that heating surface individualism before described SCR device, this kind heating surface not after SCR device.
4. the denitration control method of flue gas selective catalytic reduction device according to claim 1 and 2, it is characterized in that short circuit working medium flow in described bypass duct is working medium flow 0 to 100%.
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| CN201410096901.5A CN103846007A (en) | 2014-03-17 | 2014-03-17 | Denitration control method of flue-gas selective catalytic reduction device |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106178950A (en) * | 2016-08-25 | 2016-12-07 | 华电电力科学研究院 | A kind of low SO2/ SO3the SCR denitration system of conversion ratio |
| CN107152673A (en) * | 2017-06-06 | 2017-09-12 | 大唐贵州发耳发电有限公司 | A kind of device for improving coal-fired electric generation furnace denitration inlet flue gas temperature |
| CN109442375A (en) * | 2018-10-09 | 2019-03-08 | 中国神华能源股份有限公司 | Boiler system |
| CN110145732A (en) * | 2019-05-13 | 2019-08-20 | 哈尔滨锅炉厂有限责任公司 | Large coal powder boiler ultra-low load economizer switches bypath system |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102937296A (en) * | 2012-11-20 | 2013-02-20 | 上海锅炉厂有限公司 | Boiler suitable for denitration device negative whole process load operation |
| CN203170222U (en) * | 2013-01-18 | 2013-09-04 | 广东电网公司电力科学研究院 | System for improving running capability of SCR (selective catalytic reduction) denitrating device in power plant |
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2014
- 2014-03-17 CN CN201410096901.5A patent/CN103846007A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102937296A (en) * | 2012-11-20 | 2013-02-20 | 上海锅炉厂有限公司 | Boiler suitable for denitration device negative whole process load operation |
| CN203170222U (en) * | 2013-01-18 | 2013-09-04 | 广东电网公司电力科学研究院 | System for improving running capability of SCR (selective catalytic reduction) denitrating device in power plant |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106178950A (en) * | 2016-08-25 | 2016-12-07 | 华电电力科学研究院 | A kind of low SO2/ SO3the SCR denitration system of conversion ratio |
| CN107152673A (en) * | 2017-06-06 | 2017-09-12 | 大唐贵州发耳发电有限公司 | A kind of device for improving coal-fired electric generation furnace denitration inlet flue gas temperature |
| CN109442375A (en) * | 2018-10-09 | 2019-03-08 | 中国神华能源股份有限公司 | Boiler system |
| CN110145732A (en) * | 2019-05-13 | 2019-08-20 | 哈尔滨锅炉厂有限责任公司 | Large coal powder boiler ultra-low load economizer switches bypath system |
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Application publication date: 20140611 |
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