CN109323238B - Denitration method for supercritical direct current furnace during 8 hours of cold start - Google Patents
Denitration method for supercritical direct current furnace during 8 hours of cold start Download PDFInfo
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- CN109323238B CN109323238B CN201811076190.XA CN201811076190A CN109323238B CN 109323238 B CN109323238 B CN 109323238B CN 201811076190 A CN201811076190 A CN 201811076190A CN 109323238 B CN109323238 B CN 109323238B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B37/00—Component parts or details of steam boilers
- F22B37/008—Adaptations for flue gas purification in steam generators
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B35/00—Control systems for steam boilers
- F22B35/06—Control systems for steam boilers for steam boilers of forced-flow type
- F22B35/10—Control systems for steam boilers for steam boilers of forced-flow type of once-through type
- F22B35/12—Control systems for steam boilers for steam boilers of forced-flow type of once-through type operating at critical or supercritical pressure
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Abstract
The invention discloses a denitration method for a supercritical direct current furnace in 8 hours after cold start, which comprises the following four steps: s1: starting the supercritical direct current furnace in a cold state; s2: the flame height in the hearth of the coal-fired furnace is improved, so that the heat radiation of a flue at the tail of the hearth is enhanced, and the flue gas temperature at the tail of the hearth is quickly increased; s3: when the temperature of the flue gas at the tail of the hearth reaches 300-420 ℃, putting the denitration system into operation, and starting to grid the unit; s4: after the denitration system is put into operation, the water supply flow is determined according to the steam pressure, the temperature and the wall temperature of a water wall, the coal quantity is determined according to the water supply flow, and the visible water level of about 4.5m of the separator and the superheat degree of an outlet of the separator are guaranteed to fluctuate at about-1 ℃ and are not more than 0 ℃; the invention aims to provide a denitration method for a supercritical direct current furnace within 8 hours of cold start, which aims to solve the problem of high emission of nitrogen oxides of a coal-fired unit from the cold start of the unit to grid connection.
Description
Technical Field
The invention belongs to the field of denitration method, and particularly relates to a denitration method for a supercritical direct current furnace within 8 hours of cold start.
Background
The Selective Catalytic Reduction (SCR) technology is a denitration technology commonly adopted by coal-fired power plants at home and even in the world at present. At present, domestic units are suitable for putting the denitration system at any time and at any stage during the starting period of the units, the state does not set up a unified standard and a unified standard, and most power plants are determined according to the running conditions of the units and the requirements of the local environmental protection bureau. The denitration is put into the supercritical unit in 8 hours after cold start, the debugging period of the conventional power plant is always blank, and most of power plants have to put the denitration system into operation only when the flue gas temperature reaches 300-420 ℃ after the unit is connected to the power plant according to the conventional debugging experience. However, the time from the cold start of the unit to the grid connection is relatively long, and the discharge amount of nitrogen oxides is relatively high, which causes relatively serious pollution to the environment. The control method is mastered, and has important significance for reducing the emission of nitrogen oxides of the coal-fired unit.
Disclosure of Invention
The invention aims to provide a denitration method for a supercritical direct current furnace within 8 hours of cold start, so as to solve the problem that the emission of nitrogen oxides of a coal-fired unit is high from the cold start of the unit to grid connection.
The technical scheme provided by the invention is as follows: a denitration method for a supercritical direct current furnace in 8 hours after cold start comprises the following four steps:
s1: starting the supercritical direct current furnace in a cold state;
s2: the flame height in the hearth of the coal-fired furnace is improved, so that the heat radiation of a flue at the tail of the hearth is enhanced, and the temperature of flue gas at the tail of the hearth is quickly increased;
s3: when the temperature of the flue gas at the tail of the hearth reaches 300-420 ℃, putting the denitration system into operation, and starting to grid the unit;
s4: after the denitration system is put into operation, the water supply flow is determined according to the steam pressure, the temperature and the wall temperature of the water wall, the coal quantity is determined according to the water supply flow, and the visible water level of about 4.5m of the separator and the superheat degree of the outlet of the separator are guaranteed to fluctuate at about-1 ℃ and are not more than 0 ℃.
Preferably, the specific operation of step S2 is to adjust the opening of the movable blade of the primary air fan, so that the opening of the movable blade of the primary air fan is increased, and to finely adjust the cold and hot air adjusting doors at the coal mill inlet, so as to increase the primary air pressure at the coal mill inlet and increase the primary air speed at the coal mill inlet.
Preferably, the specific operation of step S2 is to adjust the direct-fired pulverizing system disposed at the inlet of the coal mill to reduce the hot primary air component and increase the cold primary air volume, thereby reducing the temperature of the air-powder mixture at the outlet of the coal mill.
Preferably, the specific operation of step S2 is to adjust the tilt angle of the burner, and tilt the tilt angle of the burner upward, so that the flow field of the hearth is integrally improved.
Preferably, the specific operation of step S2 is to adjust the rotary separator and reduce the frequency conversion of the rotary separator, so that the rotation speed of the coal mill rotary separator is reduced.
Preferably, in the step S2, the specific operation is to adjust the opening of the secondary air damper, and increase the opening of the secondary air damper at the bottommost layer of the burner to increase the bottom-dragging air of the furnace; meanwhile, the opening degree of the movable blades of the air feeder is increased to improve the total air quantity of the boiler, and the opening degree of the movable blades of the induced draft fan is properly increased to improve the negative pressure of a hearth under the condition that the opening degrees of the movable blades of the air feeder and the movable blades of the primary air fan are basically unchanged.
Preferably, in step S2, any one of the above specific operations is performed alone or in combination of any more specific operations.
Has the advantages that:
(1) according to the invention, the flame center in the hearth is moved upwards, so that the flame center of the hearth is improved, and the heat radiation of the tail flue of the hearth is enhanced, so that the temperature rise rate of the tail flue of the hearth is improved, the operation of a denitration system is accelerated, the excessive discharge amount of nitrogen oxides is further reduced, and the consumption of the water supply amount and the coal amount of a unit is obviously reduced.
(2) The primary air pressure at the inlet of the coal mill and the primary air speed at the inlet of the coal mill are increased by adjusting the opening of a movable blade of a primary fan, so that pulverized coal is concentrated on the upper part of a hearth for combustion, and the flame center moves upwards.
(3) The temperature of the air-powder mixture at the grinding outlet is reduced by reducing the component of hot primary air and increasing the air quantity of cold primary air, and the air-powder mixture is reduced in temperature because the pulverized coal needs a certain ignition point during combustion, so that the ignition point of the pulverized coal is delayed, the pulverized coal is not sufficiently combusted at the lower part of the hearth, the pulverized coal can be intensively combusted at the upper part of the hearth, and the flame moves upwards in the center.
(4) The swinging angle of the burner swings upwards, so that the flow field of the hearth is integrally improved, and the center of the flame is easy to move upwards.
(5) The frequency conversion of the rotary separator is reduced to reduce the rotating speed, the rotating speed of the separator plays a key role in the fineness of the pulverized coal, the pulverized coal is coarse, the pulverized coal is long in combustion time, the pulverized coal is easy to concentrate on the upper part of a hearth to be combusted, and the flame center moves upwards.
(6) Through increasing the bottom air dragged by the hearth and increasing the air supply quantity and the hearth negative pressure, the air quantity and the hearth negative pressure are increased, so that the air-powder mixture flows to the upper part of the hearth easily, and the flame center of the hearth is moved upwards easily.
(7) Step 2, any one operation or any multiple operation of the five methods for improving the central height of the flame is adopted, so that the effect of improving the height of the flame in the hearth of the coal-fired furnace is better.
Detailed Description
Examples of the present invention are further illustrated below.
In this embodiment, the method for denitration by adding into the supercritical dc furnace within 8 hours of cold start includes the following four steps:
s1: starting the supercritical direct current furnace in a cold state;
s2: the flame height in the hearth of the coal-fired furnace is improved, so that the heat radiation of a flue at the tail of the hearth is enhanced, and the temperature of flue gas at the tail of the hearth is quickly increased;
s3: when the temperature of the flue gas at the tail of the hearth reaches 300-420 ℃, putting the denitration system into operation, and starting to grid the unit;
s4: after the denitration system is put into operation, the water supply flow is determined according to the steam pressure, the temperature and the wall temperature of the water wall, the coal quantity is determined according to the water supply flow, and the visible water level of about 4.5m of the separator and the superheat degree of the outlet of the separator are guaranteed to fluctuate at about-1 ℃ and are not more than 0 ℃.
In this embodiment, the specific operation of step S2 is to adjust the movable blade opening of the primary air fan, so that the movable blade opening of the primary air fan is increased, and to finely adjust the cold and hot air adjusting doors at the coal mill inlet, so as to increase the primary air pressure at the coal mill inlet and increase the primary air speed at the coal mill inlet.
The specific operation of step S2 is to adjust the direct-fired pulverizing system installed at the coal mill inlet to reduce the hot primary air component and increase the cold primary air volume, thereby reducing the temperature of the pulverized coal mixture at the mill outlet.
The specific operation of the step S2 is to adjust the pivot angle of the burner, and pivot the pivot angle of the burner upward, so that the flow field of the hearth is integrally improved.
The specific operation of the step S2 is to adjust the rotating separator and reduce the frequency conversion of the rotating separator, so as to reduce the rotation speed of the coal mill rotating separator.
The specific operation of the step S2 is that the opening degree of the secondary small air door is adjusted, and the opening degree of the secondary small air door at the bottommost layer of the combustor is increased to increase bottom-dragging air of the hearth; meanwhile, the opening degree of the movable blades of the air feeder is increased to improve the total air volume of the boiler, and the opening degree of the movable blades of the induced draft fan is properly increased to improve the negative pressure of the hearth under the condition that the opening degrees of the movable blades of the air feeder and the movable blades of the primary air fan are basically unchanged.
In the step S2, the specific operation of any one of the foregoing S2 is performed alone or in a common combination of any plural specific operations.
By adopting the denitration method, the denitration system is put into the supercritical direct current boiler within 8 hours after the supercritical direct current boiler is started in a cold state, so that the discharge amount of nitrogen oxides can be reduced, and the loss of coal quantity, water supply flow and power consumption is obviously reduced. The method reduces the cost investment for power plants, saves resources for the country, reduces the expense investment required by the country for controlling the environment, and has good economic benefit.
The present invention is not limited to the above-described embodiments, and various modifications may be made by those skilled in the art, and any changes equivalent or similar to the present invention are intended to be included within the scope of the claims.
Claims (6)
1. A denitration method for a supercritical direct current furnace in 8 hours after cold start is characterized by comprising the following four steps:
s1: starting the supercritical direct current furnace in a cold state;
s2: the flame height in the hearth of the coal-fired furnace is improved, so that the heat radiation of a flue at the tail of the hearth is enhanced, and the flue gas temperature at the tail of the hearth is quickly increased; the specific operation of the step S2 is to adjust the rotating separator and reduce the frequency conversion of the rotating separator, so that the rotating speed of the coal mill rotating separator is reduced;
s3: when the temperature of the flue gas at the tail of the hearth reaches 300-420 ℃, putting the denitration system into operation, and starting to grid the unit;
s4: after the denitration system is put into operation, the water supply flow is determined according to the steam pressure, the temperature and the wall temperature of the water wall, the coal quantity is determined according to the water supply flow, and the visible water level of about 4.5m of the separator and the superheat degree of the outlet of the separator are guaranteed to fluctuate at about-1 ℃ and are not more than 0 ℃.
2. The denitration method of the supercritical DC furnace, which is put into the supercritical DC furnace within 8 hours after cold start, is characterized in that:
the specific operation of the step S2 is to adjust the opening of the movable blade of the primary air fan, increase the opening of the movable blade of the primary air fan, and fine-tune the cold and hot air regulating valve at the inlet of the coal pulverizer, thereby improving the primary air pressure at the inlet of the coal pulverizer and increasing the primary air speed at the inlet of the coal pulverizer.
3. The denitration method of the supercritical DC furnace, which is put into the supercritical DC furnace within 8 hours after cold start, is characterized in that:
the specific operation of step S2 is to adjust the direct-fired pulverizing system installed at the coal mill inlet, reduce the hot primary air component, and increase the cold primary air volume, thereby reducing the temperature of the pulverized coal mixture at the mill outlet.
4. The denitration method of the supercritical DC furnace, which is put into the supercritical DC furnace within 8 hours after cold start, is characterized in that:
the specific operation of the step S2 is to adjust the pivot angle of the burner, and pivot the pivot angle of the burner upward, so that the flow field of the hearth is integrally improved.
5. The denitration method of the supercritical DC furnace, which is put into the supercritical DC furnace within 8 hours after cold start, is characterized in that:
the specific operation of the step S2 is that the opening degree of the secondary small air door is adjusted, and the opening degree of the secondary small air door at the bottommost layer of the combustor is increased to increase bottom dragging air of the hearth; meanwhile, the opening degree of the movable blades of the air feeder is increased to improve the total air quantity of the boiler, and the opening degree of the movable blades of the induced draft fan is increased to improve the negative pressure of the hearth under the condition that the opening degrees of the movable blades of the air feeder and the primary air fan are basically unchanged.
6. The denitration method of the supercritical DC furnace, which is put into the supercritical DC furnace within 8 hours after cold start, is characterized in that:
in the step S2, the specific operations in any one of claims 2 to 5 are adopted to be performed alone or in a common combination of any more specific operations.
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| JPS609201B2 (en) * | 1975-09-29 | 1985-03-08 | 株式会社日立製作所 | Exhaust heat recovery boiler equipment |
| JP2000065313A (en) * | 1998-08-21 | 2000-03-03 | Babcock Hitachi Kk | Boiler apparatus and boiler starting operation method |
| CN101658757B (en) * | 2008-08-26 | 2012-09-19 | 祁伟 | High-efficiency environmental-friendly coal-saving sulphur-fixing antismoke agent and production technology thereof |
| CN107270274B (en) * | 2017-07-10 | 2021-12-14 | 江苏大唐国际吕四港发电有限责任公司 | Novel starting mode of ultra-supercritical coal-fired unit realizes unit full-load denitration input |
| CN108087904B (en) * | 2017-12-01 | 2024-04-19 | 重庆富燃科技股份有限公司 | Method for denitration of boiler in whole course |
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