CN110220212B - Method for improving thermal efficiency of boiler - Google Patents
Method for improving thermal efficiency of boiler Download PDFInfo
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- CN110220212B CN110220212B CN201910520865.3A CN201910520865A CN110220212B CN 110220212 B CN110220212 B CN 110220212B CN 201910520865 A CN201910520865 A CN 201910520865A CN 110220212 B CN110220212 B CN 110220212B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N5/00—Systems for controlling combustion
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2239/00—Fuels
- F23N2239/02—Solid fuels
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2241/00—Applications
- F23N2241/10—Generating vapour
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- Combustion & Propulsion (AREA)
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- Regulation And Control Of Combustion (AREA)
Abstract
The invention relates to a method for improving the thermal efficiency of a boiler, which comprises the following steps of adjusting the height of a refractory zone in a dense-phase area of the boiler according to the hardness of coal; adding coal into a boiler combustion chamber for combustion; detecting the temperature of a boiler furnace and the material conveying speed of feeding materials, and keeping the temperature of the boiler furnace and the material conveying speed of the feeding materials constant; detecting the amount of the coal fed into the boiler in unit time and the evaporation amount of steam generated in unit time, and calculating whether the percentage value of the evaporation amount divided by the amount of the material is greater than a preset value; if the percentage value of the evaporation amount divided by the material amount is less than the preset value, the upper part of the dense-phase area of the boiler is supplemented with the air volume for complete combustion, otherwise, the combustion is normal. Different from the prior art, the invention can change the heating area of the boiler according to the hardness of coal and reduce the temperature of a dense phase region. And supplementing the air quantity after burning according to the requirement, and performing tertiary supplementary combustion on the upper part of the dense-phase zone.
Description
Technical Field
The invention relates to the technical field of papermaking, in particular to a method for improving the thermal efficiency of a boiler.
Background
In the prior art, because the anthracite produced by Fujian is adopted, the anthracite produced by the Fujian has the characteristics of high density and small volatilization. According to the original design requirement and the original coal types, the coal sulfur content is higher, the boiler combustion efficiency is lower, according to the combustion characteristic of the circulating fluidized bed boiler, the temperature of a dense-phase area of the boiler is higher, and NO is generated by combustion2Is higher than 260mg/m3And the production cost is high in order to realize qualified emission denitration.
In recent years, the yield of anthracite produced by Fujian is too low, so that the existing boiler adopts the bituminous coal produced in Shanxi province, and the bituminous coal produced in Shanxi province has the characteristics of low density and high volatilization. Because the design of the original boiler is adopted, the boiler has poor heat efficiency and large heat loss of exhaust smoke.
Disclosure of Invention
Therefore, it is required to provide a method for improving the thermal efficiency of a boiler, which solves the technical problems of the prior art.
To achieve the above objects, the present inventors provide a method for improving thermal efficiency of a boiler, comprising the steps of:
detecting the hardness of coal to be added into the boiler;
if the hardness of the coal exceeds a preset value, increasing the height of a refractory zone in a dense-phase area of the boiler;
if the hardness of the coal is lower than a preset value, reducing the height of a refractory zone in a dense-phase area of the boiler;
after the height of the combustion control zone in the dense-phase area of the boiler is adjusted, adding coal into a boiler combustion chamber for combustion;
detecting the temperature of a boiler furnace and the material conveying speed of feeding materials, and keeping the temperature of the boiler furnace and the material conveying speed of the feeding materials constant;
detecting the amount of the coal fed into the boiler in unit time and the evaporation amount of steam generated in unit time, and calculating whether the percentage value of the evaporation amount divided by the amount of the material is greater than a preset value;
if the percentage value of the evaporation amount divided by the material amount is less than the preset value, the upper part of the dense-phase area of the boiler is supplemented with the air volume for complete combustion, otherwise, the combustion is normal.
As a preferred structure of the invention, the height of the boiler dense-phase zone combustion guard is 15m-20 m.
As a preferable structure of the invention, a circle of over-fire air ports are added at the position of 20m-24m of the central height of a boiler hearth.
In a preferred configuration of the present invention, the combustion air supply of the boiler includes a primary air, a secondary air, and a tertiary air, the primary air is located at the bottom of the combustion chamber, the secondary air is located at the side of the combustion chamber, and the tertiary air is located at the side of the combustion chamber and above the secondary air.
As a preferred structure of the invention, NO is detected in the coal combustion process2If NO is produced2If the generated quantity exceeds the preset value, the height of the combustion control zone in the dense-phase area of the boiler is reduced, otherwise, the boiler is normally combusted.
Different from the prior art, the technical scheme adjusts the height of the refractory belt in the dense-phase area of the boiler by detecting the hardness of coal needing to be added into the boiler; calculating whether the percentage value of the evaporation amount divided by the material amount is greater than a preset value or not by detecting the material amount of coal fed into the boiler in unit time and the evaporation amount of steam generated in unit time; if the percentage value of the evaporation amount divided by the material amount is larger than the preset value, the upper part of the dense-phase area of the boiler is supplemented with the air volume after burning out. Therefore, the heating area of the boiler can be changed according to the hardness of coal, and the temperature of the dense-phase area is reduced. The air quantity is supplemented according to the requirement, the upper part of the dense-phase area is subjected to three times of supplementary combustion, the evaporation capacity of the boiler is increased by 4.87%, the problem of oxygen deficiency in the dense-phase area is solved, and the thermal efficiency of the boiler is improved. The temperature of the flue gas at the outlet of the hearth is reduced by 3-5 ℃, the high-temperature corrosion is reduced, the heat loss of the exhaust smoke is reduced, and the thermal efficiency of the boiler is improved.
Drawings
FIG. 1 is a system diagram of a boiler configuration according to an embodiment;
FIG. 2 is a schematic flow diagram of a method for increasing thermal efficiency of a boiler according to an embodiment.
Description of reference numerals:
10. the temperature of the boiler is controlled by the temperature control device,
11. the dense-phase region guard burning zone is provided with a guard burning zone,
12. an over-fire tuyere.
Detailed Description
To explain technical contents, structural features, and objects and effects of the technical solutions in detail, the following detailed description is given with reference to the accompanying drawings in conjunction with the embodiments.
Referring to fig. 1 and 2, the present embodiment relates to a paper mill boiler 10, wherein a left side furnace is a combustion chamber, a right side furnace is a cyclone separator, the cyclone separator is connected to the combustion chamber through a material returning device, and a material returning fan is disposed below the material returning device. The combustion chamber is divided into a dilute phase zone at the upper part of the hearth, a dense phase zone at the lower part of the hearth and a transition zone arranged between the dilute phase zone and the dense phase zone.
A dilute phase zone at the upper part of the hearth: the particle density is small, the average particle size of the particles is small, and the gas content is high. In all conditions, the air required for combustion passes through the upper region of the furnace where the coke and a portion of the volatiles that are delivered to the upper region are combusted in an oxygen-rich state. Most of the combustion occurs in this region, generally speaking, the upper region is much higher than the lower region. The gas-solid flow characteristics of the upper dilute phase zone are very different from the flow characteristics of the dense phase zone. Therefore, the heat transfer law or mechanism is also greatly different.
Dense-phase zone at the lower part of the hearth: the particles have high density, large average particle size and much higher solid particle concentration than the upper region, so that the region is filled with the hot material, is a stable ignition heat source and is a heat storage for storing heat. The dense phase zone fluidizes the bed material and the added coal particles with primary air. The added fuel and unburned coke collected from the high temperature separator are fed into this zone. Fuel evaporation and partial combustion also occur in this region. When the load of the boiler 10 is increased, the ratio of the primary air to the secondary air is increased, so that a large amount of high-temperature material can be conveyed to the upper area of the furnace to be combusted and participate in heat and mass exchange. The overfire air may also be stopped when the boiler 10 is low on load and staged combustion is not desired.
The water-cooled walls around the combustion chamber are covered with refractory material, and the covered structure is called a refractory guard band. The refractory belt has the effects of preventing the boiler 10 from being worn and insulating heat, the height of the cast refractory belt is increased, and although the worn part can be effectively covered, the height of the refractory belt has certain influence on the evaporation capacity of the boiler 10.
Optionally, the boiler 10 has a dense phase combustion zone 11 with a height of 15m-20 m.
Optionally, in this embodiment, the combustion air supply of the boiler 10 includes primary air, secondary air and tertiary air, the primary air is located at the bottom of the combustion chamber, the secondary air is located at the side of the combustion chamber, and the tertiary air is located at the side of the combustion chamber and above the secondary air.
Optionally, a circle of over-fire air ports 12 are added at the position of 20m-24m of the central height of the hearth of the boiler 10. The boiler 10 is designed to have a dense-phase zone burning protection zone 11 with a height of 17M, and a layer of over-fire air is added at a position 22.2M higher than the center of a hearth to supplement the combustion oxygen amount according to the combustion characteristics of the circulating fluidized bed boiler 10 and the type of the bituminous coal used.
The height of the combustion belt is designed to be 17 meters, and the heating surface of the boiler 10 is increased by 44.5m2The evaporation capacity of the boiler 10 is increased by 20T/H, the temperature of a dense phase zone is reduced, and NO is reduced in the combustion process2GeneratingControlling NO2 at 160mg/m3In the following, the denitration system is not put into the system, and the environmental protection emission requirement can be met.
Designed at the position 22.2m higher than the center of the hearth, 8 burnout air ports 12 are respectively added in the front and the back, and the supplementary burnout air quantity is 20000m3And h, the upper part of the dense-phase area is subjected to three times of supplementary combustion, the evaporation capacity of the boiler 10 is increased by 4.87 percent, the problem of oxygen deficiency in the dense-phase area is solved, and the efficiency is improved.
The upper part of the burning guarding belt is made of an anti-abrasion refractory material, so that the pipe explosion caused by the abrasion of the heating surface is prevented.
On the basis, the temperature of the flue gas at the outlet of the hearth is reduced by 3-5 ℃, the high-temperature corrosion is reduced, the heat loss of the exhaust gas is reduced, and the heat efficiency of the boiler 10 is improved.
In the present embodiment, the method for improving the thermal efficiency of the boiler 10 comprises the following steps:
s101, detecting the hardness of coal needing to be added into the boiler 10;
judging that the hardness of the coal exceeds a preset value;
s1011, if the hardness of the coal exceeds a preset value, increasing the height of a refractory belt 11 in a dense-phase area of the boiler 10;
s1012, if the hardness of the coal is lower than a preset value, reducing the height of a refractory belt 11 in a dense-phase area of the boiler 10;
s102, adding the coal into a combustion chamber of the boiler 10 for combustion;
s103, detecting the temperature of the hearth of the boiler 10 and the feeding material conveying speed, and keeping the temperature of the hearth of the boiler 10 and the feeding material conveying speed constant;
s104, detecting the material quantity of coal fed into the boiler 10 in unit time and the evaporation quantity of steam generated in unit time;
judging whether the percentage value of the evaporation amount divided by the material amount is greater than a preset value or not;
s105, if the percentage value of the evaporation amount divided by the material amount is smaller than a preset value, supplementing the burnout air quantity at the upper part of the dense-phase area of the boiler 10;
and S106, otherwise, normally burning.
As a preferred process of the invention, during the coal combustion process, the generation amount of NO2 is detected, if the generation amount of NO2 exceeds a preset value, the height of the combustion guard belt 11 in the dense-phase area of the boiler 10 is reduced, otherwise, the combustion is normal.
Different from the prior art, the embodiment can adjust the height of the refractory belt 11 in the dense-phase area of the boiler 10 by detecting the hardness of coal to be added into the boiler 10; calculating whether the percentage value of the evaporation amount divided by the material amount is greater than a preset value by detecting the material amount of coal fed into the boiler 10 in unit time and the evaporation amount of steam generated in unit time; if the percentage value of the evaporation amount divided by the material amount is larger than the preset value, the upper part of the dense-phase area of the boiler 10 is supplemented with the burn-out air volume. Thus, the temperature of the dense phase zone can be reduced by changing the heating area of the boiler 10 according to the hardness of the coal. And supplementing the air quantity after burning according to the requirement, and performing tertiary supplementary combustion on the upper part of the dense-phase zone.
It should be noted that, although the above embodiments have been described herein, the invention is not limited thereto. Therefore, based on the innovative concepts of the present invention, the technical solutions of the present invention can be directly or indirectly applied to other related technical fields by making changes and modifications to the embodiments described herein, or by using equivalent structures or equivalent processes performed in the content of the present specification and the attached drawings, which are included in the scope of the present invention.
Claims (4)
1. A method of increasing the thermal efficiency of a boiler, comprising the steps of:
detecting the hardness of coal to be added into the boiler;
if the hardness of the coal exceeds a preset value, increasing the height of a refractory zone in a dense-phase area of the boiler;
if the hardness of the coal is lower than a preset value, reducing the height of a refractory zone in a dense-phase area of the boiler;
after the height of the combustion control zone in the dense-phase area of the boiler is adjusted, adding coal into a boiler combustion chamber for combustion;
detecting the temperature of a boiler furnace and the material conveying speed of feeding materials, and keeping the temperature of the boiler furnace and the material conveying speed of the feeding materials constant;
detecting the amount of the coal fed into the boiler in unit time and the evaporation amount of steam generated in unit time, and calculating whether the percentage value of the evaporation amount divided by the amount of the material is greater than a preset value;
if the percentage value of the evaporation amount divided by the material amount is smaller than the preset value, supplementing the burnout air quantity at the upper part of the dense-phase area of the boiler, and if not, normally burning;
and in the coal combustion process, detecting the generation amount of NO2, and if the generation amount of NO2 exceeds a preset value, reducing the height of a combustion zone in a dense-phase area of the boiler, otherwise, normally combusting.
2. The method for improving the thermal efficiency of a boiler according to claim 1, wherein: the height of the combustion guard zone in the dense-phase area of the boiler is 15m-20 m.
3. The method for improving the thermal efficiency of a boiler according to claim 2, wherein: and a circle of over-fire air ports are added at the position of 20-24 m of the central height of the boiler hearth.
4. The method for improving the thermal efficiency of a boiler according to claim 1, wherein: the combustion air supply of boiler includes once-wind, overgrate air and tertiary air, once the wind is located the bottom of combustion chamber, the overgrate air is located the side of combustion chamber, the tertiary air is located the side of combustion chamber, and is located the top of overgrate air.
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| CN201910520865.3A CN110220212B (en) | 2019-06-17 | 2019-06-17 | Method for improving thermal efficiency of boiler |
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| CN201910520865.3A CN110220212B (en) | 2019-06-17 | 2019-06-17 | Method for improving thermal efficiency of boiler |
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| CN110220212B true CN110220212B (en) | 2020-10-30 |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU802401A1 (en) * | 1979-02-21 | 1981-02-07 | Иркутский Филиал Всесоюзного Научно- Исследовательского И Проектногоинститута Алюминиевой, Магниевой Иэлектродной Промышленности | Cathode device of electrolyzer |
| CN1189591A (en) * | 1997-01-29 | 1998-08-05 | 长沙电力学院 | Rotary plate type adjustable burning guarding belt |
| CN201281346Y (en) * | 2008-09-28 | 2009-07-29 | 北京中科通用能源环保有限责任公司 | CFB incineration boiler for sludge and garbage multifuel combustion |
| CN105003901A (en) * | 2015-07-01 | 2015-10-28 | 赵丽颖 | Boiler thermodynamic system for conducting automatic control based on steam fuel consumption |
| CN206803212U (en) * | 2017-05-04 | 2017-12-26 | 云南电力试验研究院(集团)有限公司 | A kind of venetian blind type adjustable burning guarding belt device |
-
2019
- 2019-06-17 CN CN201910520865.3A patent/CN110220212B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU802401A1 (en) * | 1979-02-21 | 1981-02-07 | Иркутский Филиал Всесоюзного Научно- Исследовательского И Проектногоинститута Алюминиевой, Магниевой Иэлектродной Промышленности | Cathode device of electrolyzer |
| CN1189591A (en) * | 1997-01-29 | 1998-08-05 | 长沙电力学院 | Rotary plate type adjustable burning guarding belt |
| CN201281346Y (en) * | 2008-09-28 | 2009-07-29 | 北京中科通用能源环保有限责任公司 | CFB incineration boiler for sludge and garbage multifuel combustion |
| CN105003901A (en) * | 2015-07-01 | 2015-10-28 | 赵丽颖 | Boiler thermodynamic system for conducting automatic control based on steam fuel consumption |
| CN206803212U (en) * | 2017-05-04 | 2017-12-26 | 云南电力试验研究院(集团)有限公司 | A kind of venetian blind type adjustable burning guarding belt device |
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