CN114791748A - Temperature control system of boiler - Google Patents
Temperature control system of boiler Download PDFInfo
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- CN114791748A CN114791748A CN202210558682.2A CN202210558682A CN114791748A CN 114791748 A CN114791748 A CN 114791748A CN 202210558682 A CN202210558682 A CN 202210558682A CN 114791748 A CN114791748 A CN 114791748A
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- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims abstract description 87
- 239000003546 flue gas Substances 0.000 claims abstract description 87
- 238000005338 heat storage Methods 0.000 claims abstract description 78
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 75
- 239000003245 coal Substances 0.000 claims abstract description 7
- 238000010438 heat treatment Methods 0.000 claims description 25
- 239000002918 waste heat Substances 0.000 claims description 11
- 239000000428 dust Substances 0.000 claims description 9
- 230000009467 reduction Effects 0.000 claims description 9
- 238000011084 recovery Methods 0.000 claims description 8
- 230000001172 regenerating effect Effects 0.000 claims description 6
- 238000001816 cooling Methods 0.000 claims description 3
- 230000006872 improvement Effects 0.000 description 8
- 238000006722 reduction reaction Methods 0.000 description 8
- 238000000034 method Methods 0.000 description 7
- 239000007789 gas Substances 0.000 description 6
- 230000008569 process Effects 0.000 description 5
- 239000000779 smoke Substances 0.000 description 5
- 230000008859 change Effects 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 238000010248 power generation Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000010531 catalytic reduction reaction Methods 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000003517 fume Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D23/00—Control of temperature
- G05D23/19—Control of temperature characterised by the use of electric means
- G05D23/20—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/34—Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery
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Abstract
The invention discloses a temperature control system of a boiler, wherein a flue bypass is communicated in a main flue of the boiler, an openable flue baffle is arranged between the main flue and the flue bypass, a coal economizer and a denitration device are respectively arranged in the main flue according to the flow direction of flue gas, a high-temperature flue gas heat exchanger is arranged in the flue bypass, the high-temperature flue gas heat exchanger is connected with a high-temperature heat storage unit, the coal economizer is connected with a feed water heater, and when a power station unit is in a load-up or high-load operation working condition, the flue baffle is opened, so that the flue gas flows through the high-temperature flue gas heat exchanger and stores redundant heat through the high-temperature heat storage unit to reduce the temperature of the flue gas in the main flue; when the load of the power station unit is reduced or the working condition of deep peak regulation is adopted, the flue baffle is closed, the heat stored by the high-temperature heat storage unit is released, the water temperature at the inlet of the economizer is increased through the feed water heater, and the flue gas temperature before denitration of the denitration device in the main flue is increased. When the load of the power station unit is changed, the temperature of the flue gas of the main flue is controlled within a reasonable range, the denitration efficiency of the flue gas of the main flue is improved, and the stable operation of the system is maintained.
Description
Technical Field
The invention belongs to the technical field of variable load regulation of a coal-fired power station boiler, and particularly relates to a temperature control system of a boiler.
Background
Under the strategic goal of 'double carbon', the renewable energy power generation scale of China is continuously enlarged, but coal still occupies the basic energy position in the primary energy composition of China. Coal will continuously play an important role in the aspects of guaranteeing energy safety, promoting new energy consumption and the like. The coal-fired power plant is one of the main sources of atmospheric pollutants, and in the coal-fired power generation process, flue gas treatment such as desulfurization, denitration, dust removal and the like is an essential process.
At present, a mainstream smoke denitration mode adopted by a power plant is selective catalytic reduction denitration (SCR), the mode has an optimal operation temperature interval which is about 320 plus 420 ℃, and due to the fact that renewable energy is accessed and a coal-fired unit participates in peak shaving, the frequent startup and shutdown and variable load conditions of power grid dispatching are more and more obvious. The flue gas temperature at the SCR inlet can change along with the variable load operation of a power plant, and the deviation from an optimal reaction temperature interval can reduce the removal efficiency. In addition, in the unit variable load or deep peak regulation process, the air temperature of the air inlet of the boiler and the temperature of the flue gas are controlled within a reasonable range, and the control method is also very important for stable operation of the unit.
Disclosure of Invention
In order to solve at least one of the above technical problems, the present invention provides a temperature control system for a boiler.
The purpose of the invention is realized by the following technical scheme:
the invention provides a temperature control system of a boiler, wherein a flue bypass is communicated in a main flue of the boiler, a flue baffle which can be opened or closed is arranged between the main flue and the flue bypass, a coal economizer and a denitration device are respectively arranged in the main flue according to the flow direction of flue gas, a high-temperature flue gas heat exchanger is arranged in the flue bypass, the high-temperature flue gas heat exchanger is connected with a high-temperature heat storage unit, the coal economizer is connected with a water supply heater, the water supply heater is connected with the high-temperature heat storage unit, and when a power station unit is in load-up operation or high-load operation working condition, the flue baffle is opened, so that the flue gas flows through the high-temperature flue gas heat exchanger and stores redundant heat through the high-temperature heat storage unit to reduce the temperature of the flue gas in the main flue; when the power station unit is in load reduction operation or in deep peak regulation working condition, the flue baffle is closed, the heat stored by the high-temperature heat storage unit is released, the inlet water temperature of the economizer is increased through the feed water heater, and the flue gas temperature in the main flue is further increased.
As a further improvement, the high-temperature heat storage unit comprises a high-temperature heat storage hot tank and a high-temperature heat storage cold tank, a working medium side outlet of the high-temperature flue gas heat exchanger is connected with a working medium side inlet of the high-temperature heat storage hot tank through a heat exchange hot tank valve, a working medium side outlet of the high-temperature heat storage hot tank is connected with a working medium side inlet of the water supply heater through a hot tank heating valve, a working medium side outlet of the water supply heater is connected with a working medium side inlet of the high-temperature heat storage cold tank through a heating cold tank valve, and a working medium side outlet of the high-temperature heat storage cold tank is connected with a working medium side inlet of the high-temperature flue gas heat exchanger through a cold tank heat exchange valve.
The system is characterized by comprising a feedwater backheating unit used in variable load operation of a power station unit, wherein an outlet of the feedwater backheating unit is connected with a water side inlet of a feedwater heater, and a water side outlet of the feedwater heater is connected with a water side inlet of an economizer.
As a further improvement, the air heating unit used in the variable load operation of the power station unit is further included, the air heating unit comprises a fan heater and an air preheater, an air side inlet of the fan heater is connected with a cold air source, a primary air side outlet of the fan heater is connected with a primary air bin inlet of the air preheater, and a primary air bin outlet of the air preheater is connected with an air inlet of a boiler.
As a further improvement, the air heating unit further comprises a secondary air heater, a secondary air side outlet of the air heater is connected with a secondary air bin inlet of the air preheater, a secondary air bin outlet of the air preheater is connected with an air side inlet of the secondary air heater, and an air side outlet of the secondary air heater is connected with an air inlet of the boiler.
As a further improvement, a first working medium side outlet of the secondary air heater is connected with a working medium side inlet of the high-temperature heat storage and heat storage tank through a secondary air first inlet valve, and a second working medium side inlet of the secondary air heater is connected with a working medium side outlet of the high-temperature heat storage and heat storage tank through a secondary air second inlet valve.
As a further improvement, a third working medium side outlet of the secondary air heater is connected with a working medium side inlet of the high-temperature heat storage and cooling tank through a secondary air third inlet valve, and a fourth working medium side inlet of the secondary air heater is connected with a working medium side outlet of the high-temperature heat storage and heating tank through a secondary air fourth inlet valve.
As a further improvement, a dust removal device is arranged at a tail pipe of the main flue, and a flue gas waste heat recovery unit is arranged between the denitration device and the dust removal device.
As a further improvement, the flue gas waste heat recovery unit includes the low temperature gas heater who sets up in the flue stack and sets up the low temperature heat storage jar outside the flue stack, the water side export and the low temperature gas heater water side entry linkage of fan heater, fan heater water side entry and low temperature gas heater's water side exit linkage, the entry and the export of low temperature heat storage jar are respectively through the water side exit linkage of heat-retaining heat transfer valve and low temperature heat transfer valve with low temperature gas heater.
As a further improvement, a water medium pump is arranged between the low-temperature flue gas heat exchanger and the air heater, an inlet of the water medium pump is connected with an outlet at the water side of the air heater, and an outlet of the water medium pump is connected with an inlet at the water side of the low-temperature flue gas heat exchanger.
According to the temperature control system of the boiler, a flue bypass is communicated in a main flue of the boiler, an openable or closable flue baffle is arranged between the main flue and the flue bypass, an economizer and a denitration device are respectively arranged in the main flue according to the flow direction of flue gas, a high-temperature flue gas heat exchanger is arranged in the flue bypass, the high-temperature flue gas heat exchanger is connected with a high-temperature heat storage unit, the economizer is connected with a water supply heater, the water supply heater is connected with the high-temperature heat storage unit, and when a power station unit is in load-up operation or high-load operation working condition, the flue baffle is opened, so that the flue gas flows through the high-temperature flue gas heat exchanger and stores redundant heat through the high-temperature heat storage unit to reduce the temperature of the flue gas in the main flue; when the power station unit is in load reduction operation or in deep peak regulation working condition, the flue baffle is closed, the heat stored by the high-temperature heat storage unit is released, the inlet water temperature of the economizer is improved through the feed water heater, and then the flue gas temperature before denitration of the denitration device in the main flue is improved.
The invention has the following beneficial effects:
1) in the process of variable load operation or deep peak regulation of the power station unit, the inlet flue gas temperature of the denitration device does not change along with the variable load operation of the power station unit, and the inlet flue gas temperature of the denitration device is adjusted to be controlled within an optimal operation temperature range of about 320-420 ℃ by opening or closing the flue baffle, so that the denitration efficiency of the flue gas is improved;
2) when the power station unit is operated under variable load, the temperature of the flue gas of the main flue is controlled within a reasonable range, and the stable operation load of deep peak shaving of the unit is favorably reduced.
Drawings
The invention is further illustrated by means of the attached drawings, but the embodiments in the drawings do not constitute any limitation to the invention, and for a person skilled in the art, without inventive effort, further drawings may be derived from the following figures.
FIG. 1 is a schematic structural diagram of the present invention.
Detailed Description
In order to make those skilled in the art better understand the technical solution of the present invention, the following detailed description of the present invention is provided with reference to the accompanying drawings and specific embodiments, and it is to be noted that the embodiments and features of the embodiments of the present application can be combined with each other without conflict.
Referring to fig. 1, an embodiment of the present invention provides a temperature control system for a boiler, where a flue bypass 19 is connected to a main flue 18 of the boiler 1, a flue damper 3 that can be opened or closed is disposed between the main flue 18 and the flue bypass 19, and the flue damper 3 can be set to a structure in which upper and lower ends can be opened or closed at the same time, so as to facilitate inflow and outflow of flue gas in the main flue 18. The main flue 18 is provided with an economizer 2 and a denitration device 16 respectively according to the flow direction of flue gas, and the denitration mode of the denitration device 16 includes but is not limited to: the denitration method adopted in the embodiment is SCR denitration, and the economizer 2 is disposed at the main flue 18 and the flue damper 3.
The flue bypass 19 is internally provided with a high-temperature flue gas heat exchanger 4, and the high-temperature flue gas heat exchanger 4 is connected with a high-temperature heat storage unit. The economizer 2 is connected with a feed water heater 7, the feed water heater 7 is connected with a high-temperature heat storage unit, an outlet at the water side of the feed water heater 7 is connected with an inlet at the water side of the economizer 2, the feed water heater 7 belongs to a liquid-liquid heat exchanger, and high-temperature fluid is used for heating low-temperature fluid. Specifically, the high-temperature heat storage unit comprises a high-temperature heat storage hot tank 5 and a high-temperature heat storage cold tank 6, and media in the high-temperature heat storage hot tank 5 and the high-temperature heat storage cold tank 6 are molten salts. The working medium side outlet of the high-temperature flue gas heat exchanger 4 is connected with the working medium side inlet of the high-temperature heat storage hot tank 5 through a heat exchange hot tank valve 141, the working medium side outlet of the high-temperature heat storage hot tank 5 is connected with the working medium side inlet of the water supply heater 7 through a hot tank heating valve 146, the working medium side outlet of the water supply heater 7 is connected with the working medium side inlet of the high-temperature heat storage cold tank 6 through a heating cold tank valve 144, and the working medium side outlet of the high-temperature heat storage cold tank 6 is connected with the working medium side inlet of the high-temperature flue gas heat exchanger 4 through a cold tank heat exchange valve 142. To facilitate automated production, a controller may be used, which is connected to the heat exchange hot tank valve 141, the hot tank heating valve 146, the heating cold tank valve 144, and the cold tank heat exchange valve 142, respectively, to control the opening or closing of the valves, each valve defaulting to a closed state.
When the power station unit is in load-up operation or high-load operation working condition, the controller controls the flue baffle 3 and the heat exchange hot tank valve 141 to be opened, and controls the hot tank heating valve 146 to be closed, so that the flue gas in the main flue 18 flows through the high-temperature flue gas heat exchanger 4, and the heat is stored in the high-temperature heat storage hot tank 5 to store the redundant heat, and the temperature of the flue gas in the main flue 18 is reduced. In order to further improve the cooling efficiency, the controller controls the cold tank heat exchange valve 142 to be opened, and the cold in the high-temperature heat storage cold tank 6 is discharged to the main flue 18 from the flue bypass 19 through the cold tank heat exchange valve 142 and the high-temperature flue gas heat exchanger 4.
When the load reduction operation or the deep peak regulation working condition of the power station unit is carried out, the controller controls the flue baffle 3 to be closed, controls the hot tank heating valve 146 to be opened, controls the heating cold tank valve 144 to be closed, releases heat stored in the high-temperature heat storage hot tank 5 in the high-temperature heat storage unit, and improves the inlet water temperature of the economizer 2 through the feed water heater 7, so that the flue gas temperature before denitration of the denitration device 16 in the main flue 18 is improved.
The temperature control system is a variable load temperature control regulation and control system for coupling heat storage, the inlet flue gas temperature of the denitration device 16 does not change along with the variable load operation of the power station unit in the variable load operation or deep peak regulation process of the power station unit, and the inlet flue gas temperature of the denitration device 16 is regulated to be controlled in an optimal operation temperature range of about 320-420 ℃ by opening or closing the flue baffle 3, so that the denitration efficiency of the flue gas in the main flue 18 is improved; the temperature of the flue gas in the main flue 18 is controlled in a reasonable range, which is beneficial to reducing the stable operation load of deep peak shaving of the unit.
As a further preferred embodiment, the regenerative feedwater unit 13 is included, and the regenerative feedwater unit 13 is used in variable load operation of the power plant unit, and the regenerative feedwater unit 13 is connected to the feedwater heater 7, specifically, the regenerative feedwater unit 13 includes a condenser, a low-temperature heater connected to the condenser, a steam generator connected to the low-temperature heater, and a high-temperature heater connected to the steam generator, and an outlet of the high-temperature heater is connected to a water-side inlet of the feedwater heater 7. When the power station unit is in load reduction operation or in a deep peak regulation working condition, the water supply backheating unit 13 supplies heat to the water supply heater 7 to improve the inlet water temperature of the economizer 2, so that the flue gas temperature in the main flue 18 is improved.
As a further preferred embodiment, the system further comprises an air heating unit used in variable load operation of the power station unit, when the load reduction operation or the deep peak regulation working condition of the power station unit is performed, the air heating unit comprises an air heater 10 and an air preheater 8, an air side inlet of the air heater 10 is connected with a cold air source, a primary air side outlet of the air heater 10 is connected with a primary air bin inlet of the air preheater 8, and a primary air bin outlet of the air preheater 8 is connected with an air inlet of the boiler 1. Under the load reduction operation or the deep peak regulation working condition of the unit, the air heater 10 and the air preheater 8 are used for improving the temperature of an air inlet of the boiler 1, further improving the inlet flue gas temperature of a denitration device in the main flue 18 and the primary air temperature of the boiler 1, and reducing the stable operation load of the deep peak regulation of the unit of the power station.
As a further preferred embodiment, the air heating unit further includes a secondary air heater 15, in this case, the air heater 10 is a secondary air heater, a secondary air outlet of the air heater 10 is connected to a secondary air inlet of the air preheater 8, a secondary air outlet of the air preheater 8 is connected to an air inlet of the secondary air heater 15, and an air outlet of the secondary air heater 15 is connected to an air inlet of the boiler 1. Under the load reduction operation or the deep peak regulation working condition of the unit, the temperature of an air inlet of the boiler 1 is improved through the air heater 10, the air preheater 8 and the secondary air heater 15, the inlet flue gas temperature of the denitration device in the main flue 18 and the secondary air temperature of the boiler 1 are further improved, and the stable operation load of the deep peak regulation of the power station unit is reduced.
In a further preferred embodiment, the first working medium side outlet 51 of the secondary air heater 15 is connected to the working medium side inlet of the high temperature heat storage and heat storage tank 5 through the secondary air first inlet valve 140, and the second working medium side inlet 52 of the secondary air heater 15 is connected to the working medium side outlet of the high temperature heat storage and heat storage tank 6 through the secondary air second inlet valve 143. A controller may be used that is connected to the overfire air first inlet valve 140 and the overfire air second inlet valve 143, respectively, to control the opening or closing of the valves, with the valves defaulting to a closed state. Under the working condition of load-rising operation or high-load operation of a power station unit, if the temperature of secondary air entering a boiler 1 is too high, on the basis of opening a flue baffle 3 and opening a heat exchange hot tank valve 141 and a cold tank heat exchange valve 142, a secondary air second inlet valve 143 and a secondary air first inlet valve 140 are opened, the excessive heat of a part of secondary air heaters 15 is recovered to a high-temperature heat storage hot tank 5 through the secondary air first inlet valve 140, the cold of a high-temperature heat storage cold tank 6 enters the secondary air heaters 15 through the secondary air second inlet valve 143, and the temperature of the secondary air of the boiler 1 is maintained at a reasonable level.
In a further preferred embodiment, the third working medium side outlet 53 of the secondary air heater 15 is connected to the working medium side inlet of the high temperature heat and cold storage tank 6 through a secondary air third inlet valve 145, and the fourth working medium side inlet 54 of the secondary air heater 15 is connected to the working medium side outlet of the high temperature heat and cold storage tank 5 through a secondary air fourth inlet valve 147. A controller may be used that is connected to the third inlet valve 145 for overfire air and the fourth inlet valve 147 for overfire air, respectively, and controls the opening or closing of the valves, with the valves defaulting to a closed state. Under the load reduction operation or the deep peak regulation working condition of the power station unit, the flue baffle 3 is closed, the third inlet valve 145 of the secondary air and the fourth inlet valve 147 of the secondary air are opened, the cold energy of the secondary air heater 15 is stored to the high-temperature heat storage cold tank 6 through the third inlet valve 145, the medium in the high-temperature heat storage hot tank 5 is released to the secondary air heater 15 through the fourth inlet valve 147 of the secondary air to improve the temperature of the secondary air of the boiler 1, meanwhile, the heating valve 146 of the hot tank is opened, and the medium flows through the feed water heater 7 to improve the inlet temperature of the economizer 2, so that the inlet flue gas temperature of the denitration device is improved, and the stable operation load of the deep peak regulation of the unit is reduced.
As a further preferred embodiment, a dust removing device 17 is provided at a tail pipe of the main flue 18, and the dust removing device 17 includes, but is not limited to: the ceramic filter device or the metal fiber filter device aims at filtering and removing toxic and harmful smoke dust in smoke, and a smoke waste heat recovery unit is arranged between the denitration device 16 and the dust removal device 17 and used for recovering waste heat of the smoke in the main flue 18.
As a further preferred embodiment, the flue gas waste heat recovery unit includes the low temperature flue gas heat exchanger 9 that sets up in the main flue 18 and the low temperature heat storage tank 12 that sets up outside the main flue 18, and the medium in the low temperature heat storage tank 12 is pressurized water, the water side export of air heater 10 is connected with the water side entry of low temperature flue gas heat exchanger 9, the water side entry of air heater 10 is connected with the water side exit linkage of low temperature flue gas heat exchanger 9, the entry and the export of low temperature heat storage tank 12 are respectively through the water side exit linkage of heat-retaining heat transfer valve 148 and low temperature heat transfer valve 149 with low temperature flue gas heat exchanger 9. When the exhaust gas temperature of the main flue 18 is high, the heat storage heat exchange valve 148 is opened, the low-temperature heat exchange valve 149 is closed, the heat of the exhaust gas of the main flue 18 is absorbed through the water medium, part of the heat is stored in the low-temperature heat storage tank 12, and part of the heat flows into the water side inlet of the air heater 10; when the temperature of the exhaust fume of the main flue 18 is low, the heat storage heat exchange valve 148 is closed, the low-temperature heat exchange valve 149 is opened, and the hot water medium stored in the low-temperature heat storage tank 12 is released to supplement the heat required by the air heater 10.
As a further preferred embodiment, a water medium pump 11 is arranged between the low-temperature flue gas heat exchanger 9 and the air heater 10, an inlet of the water medium pump 11 is connected with an outlet at the water side of the air heater 10, an outlet of the water medium pump 11 is connected with an inlet at the water side of the low-temperature flue gas heat exchanger 9, if the exhaust temperature of the main flue 18 is too high, the water medium flow of the flue gas waste heat recovery system is increased, meanwhile, the heat storage and exchange valve 148 is opened, and water which absorbs flue gas waste heat through the warm flue gas heat exchanger 9 is stored in the low-temperature heat storage tank 12, so that the exhaust temperature of the main flue 18 is reduced.
According to the invention, through the air heating unit and the flue gas waste heat recovery unit, when the load of the power station unit is changed, the flue gas temperature of the main flue 18, the secondary air temperature at the boiler inlet and the flue gas temperature can be controlled within a reasonable range, the denitration efficiency of the flue gas in the main flue 18 is improved, the stable operation of the system is maintained, and the flue gas waste heat is efficiently recovered.
In the description above, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described herein, and therefore should not be construed as limiting the scope of the present invention.
In conclusion, although the present invention has been described with reference to the preferred embodiments, it should be noted that various changes and modifications can be made by those skilled in the art, and they should be included in the scope of the present invention unless they depart from the scope of the present invention.
Claims (10)
1. A temperature control system of a boiler is characterized in that a flue bypass (19) is communicated in a main flue (18) of the boiler (1), a flue baffle (3) which can be opened or closed is arranged between the main flue (18) and the flue bypass (19), the main flue (18) is internally provided with a coal economizer (2) and a denitration device (16) respectively according to the flow direction of flue gas, a high-temperature flue gas heat exchanger (4) is arranged in the flue bypass (19), the high-temperature flue gas heat exchanger (4) is connected with a high-temperature heat storage unit, the economizer (2) is connected with a feed water heater (7), the feed water heater (7) is connected with a high-temperature heat storage unit, when the power station unit is in load-up operation or high-load operation working condition, the flue baffle (3) is opened, so that the flue gas in the main flue (18) flows through the high-temperature flue gas heat exchanger (4) and the temperature of the flue gas in the main flue (18) is reduced by storing redundant heat through the high-temperature heat storage unit; when the power station unit is in load reduction operation or in a deep peak regulation working condition, the flue baffle (3) is closed, heat stored by the high-temperature heat storage unit is released, the inlet water temperature of the economizer (2) is increased through the feed water heater (7), and the flue gas temperature before denitration of the denitration device (16) in the main flue (18) is further increased.
2. The temperature control system of a boiler according to claim 1, wherein the high temperature heat storage unit comprises a high temperature heat storage hot tank (5) and a high temperature heat storage cold tank (6), the working medium side outlet of the high temperature flue gas heat exchanger (4) is connected with the working medium side inlet of the high temperature heat storage hot tank (5) through a heat exchange hot tank valve (141), the working medium side outlet of the high temperature heat storage hot tank (5) is connected with the working medium side inlet of the water supply heater (7) through a hot tank heating valve (146), the working medium side outlet of the water supply heater (7) is connected with the working medium side inlet of the high temperature heat storage cold tank (6) through a heating cold tank valve (144), and the working medium side outlet of the high temperature heat storage cold tank (6) is connected with the working medium side inlet of the high temperature flue gas heat exchanger (4) through a cold tank heat exchange valve (142).
3. A temperature control system of a boiler according to claim 1, characterized by comprising a regenerative feedwater unit (13) for use in variable load operation of the power plant, the outlet of said regenerative feedwater unit (13) being connected to the inlet of the feedwater heater (7) on the water side, and the outlet of the feedwater heater (7) on the water side being connected to the inlet of the economizer (2) on the water side.
4. A temperature control system of a boiler according to claim 1, characterized by comprising an air heating unit used in variable load operation of a power plant unit, wherein the air heating unit comprises a wind heater (10) and an air preheater (8), an air side inlet of the wind heater (10) is connected with a cold wind source, a primary wind side outlet of the wind heater (10) is connected with a primary wind bin inlet of the air preheater (8), and a primary wind bin outlet of the air preheater (8) is connected with an air inlet of the boiler (1).
5. A temperature control system of a boiler according to claim 4, characterized in that the air heating unit further comprises a secondary air heater (15), the secondary air side outlet of the air heater (10) is connected with the secondary air inlet of the air preheater (8), the secondary air outlet of the air preheater (8) is connected with the air side inlet of the secondary air heater (15), and the air side outlet of the secondary air heater (15) is connected with the air inlet of the boiler (1).
6. The temperature control system of a boiler according to claim 5, characterized in that the first working medium side outlet (51) of the secondary air heater (15) is connected with the working medium side inlet of the high temperature heat storage and heat storage tank (5) through a secondary air first inlet valve (140), and the second working medium side inlet (52) of the secondary air heater (15) is connected with the working medium side outlet of the high temperature heat storage and cold storage tank (6) through a secondary air second inlet valve (143).
7. The temperature control system of a boiler according to claim 5, wherein the third working medium side outlet (53) of the secondary air heater (15) is connected with the working medium side inlet of the high temperature heat-storage cooling tank (6) through a secondary air third inlet valve (145), and the fourth working medium side inlet (54) of the secondary air heater (15) is connected with the working medium side outlet of the high temperature heat-storage heating tank (5) through a secondary air fourth inlet valve (147).
8. The temperature control system of a boiler according to claim 4, wherein a dust removing device (17) is arranged at a tail pipe of the main flue (18), and a flue gas waste heat recovery unit is arranged between the denitration device (16) and the dust removing device (17).
9. The temperature control system of a boiler according to claim 8, wherein the flue gas waste heat recovery unit comprises a low-temperature flue gas heat exchanger (9) arranged in the main flue (18) and a low-temperature heat storage tank (12) arranged outside the main flue (18), a water side outlet of the air heater (10) is connected with a water side inlet of the low-temperature flue gas heat exchanger (9), a water side inlet of the air heater (10) is connected with a water side outlet of the low-temperature flue gas heat exchanger (9), and an inlet and an outlet of the low-temperature heat storage tank (12) are respectively connected with a water side outlet of the low-temperature flue gas heat exchanger (9) through a heat storage and exchange valve (148) and a low-temperature heat exchange valve (149).
10. A temperature control system for a boiler according to claim 9, characterized in that a water medium pump (11) is provided between the low temperature flue gas heat exchanger (9) and the air heater (10), the inlet of the water medium pump (11) is connected with the outlet of the water side of the air heater (10), and the outlet of the water medium pump (11) is connected with the inlet of the water side of the low temperature flue gas heat exchanger (9).
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