CN114791748B - Temperature control system of boiler - Google Patents
Temperature control system of boiler Download PDFInfo
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- CN114791748B CN114791748B CN202210558682.2A CN202210558682A CN114791748B CN 114791748 B CN114791748 B CN 114791748B CN 202210558682 A CN202210558682 A CN 202210558682A CN 114791748 B CN114791748 B CN 114791748B
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- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims abstract description 93
- 239000003546 flue gas Substances 0.000 claims abstract description 93
- 238000005338 heat storage Methods 0.000 claims abstract description 80
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 70
- 230000009467 reduction Effects 0.000 claims abstract description 8
- 238000010438 heat treatment Methods 0.000 claims description 24
- 239000002918 waste heat Substances 0.000 claims description 11
- 239000000428 dust Substances 0.000 claims description 9
- 238000011084 recovery Methods 0.000 claims description 9
- 239000000779 smoke Substances 0.000 description 9
- 230000006872 improvement Effects 0.000 description 8
- 238000000034 method Methods 0.000 description 6
- 238000006722 reduction reaction Methods 0.000 description 6
- 230000008569 process Effects 0.000 description 5
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 238000010531 catalytic reduction reaction Methods 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000001816 cooling 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
- 238000007599 discharging 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
- 239000007789 gas 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
- 231100000719 pollutant Toxicity 0.000 description 1
- 238000010248 power generation Methods 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
Classifications
-
- 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
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- 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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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Automation & Control Theory (AREA)
- Air Supply (AREA)
Abstract
The invention discloses a temperature control system of a boiler, 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, an economizer and a denitration device are respectively arranged in the main flue according to the flue gas flow direction, 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 feed water heater, and when a power station unit is in a load lifting or high-load operation condition, the flue baffle is opened to enable flue gas to flow through the high-temperature flue gas heat exchanger and store surplus heat through the high-temperature heat storage unit so as to reduce the flue gas temperature in the main flue; and when the power station unit is in a load reduction or deep peak regulation working condition, 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 then the flue gas temperature before denitration of the main flue internal denitration device is increased. When the power station unit changes load, the temperature of the main flue gas is controlled within a reasonable range, the denitration efficiency of the main flue gas 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 plant boiler, and particularly relates to a temperature control system of the boiler.
Background
Coal-fired power plants are one of the main sources of atmospheric pollutants, and in the coal-fired power generation process, flue gas treatment such as desulfurization, denitrification and dust removal is an indispensable process.
At present, a main stream flue gas denitration mode adopted by a power plant is selective catalytic reduction denitration (SCR), an optimal operation temperature interval exists in the mode, the temperature is about 320-420 ℃, and the frequent start-up and shutdown and load changing conditions of power grid dispatching are more and more obvious due to renewable energy source access and coal-fired units participating in peak shaving. The temperature of the flue gas at the SCR inlet can change along with the variable load operation of the power plant, and the removal efficiency can be reduced when the temperature deviates from the optimal reaction temperature interval. In addition, in the process of variable load or deep peak regulation of the unit, the air temperature and the flue gas temperature of the air inlet of the boiler are controlled in a reasonable range, and the stable operation of the unit is also very important.
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 aim of the invention is achieved by the following technical scheme:
the invention provides a temperature control system of a 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 flue gas flow direction, 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 feed water heater, the feed water heater is connected with the high-temperature heat storage unit, and when the power station unit operates under the load-lifting or high-load operation condition, the flue baffle is opened to enable flue gas to flow through the high-temperature flue gas heat exchanger and store surplus heat through the high-temperature heat storage unit to reduce the temperature of the flue gas in the main flue; and when the power station unit is in load reduction operation or 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, the working medium side outlet of the high-temperature flue gas heat exchanger is connected with the working medium side inlet of the high-temperature heat storage hot tank through a heat exchange hot tank valve, the working medium side outlet of the high-temperature heat storage hot tank is connected with the working medium side inlet of the feedwater heater through a hot tank heating valve, the working medium side outlet of the feedwater heater is connected with the working medium side inlet of the high-temperature heat storage cold tank through a heating cold tank valve, and the working medium side outlet of the high-temperature heat storage cold tank is connected with the working medium side inlet of the high-temperature flue gas heat exchanger through a cold tank heat exchange valve.
As a further improvement, the device comprises a feedwater backheating unit used in the variable load operation of the power station unit, wherein an outlet of the feedwater backheating unit is connected with a water side inlet of the feedwater heater, and a water side outlet of the feedwater heater is connected with a water side inlet of the economizer.
The utility model provides a power station unit, including the utility model, the utility model is characterized by also including the air heating unit that uses when power station unit becomes the load operation, the air heating unit includes warm braw ware and air heater, the cold wind source is connected to the air side entry of warm braw ware, the primary air storehouse entry linkage of air heater of primary air side exit linkage air heater, air heater's primary air storehouse export and boiler's air intake connection.
As a further improvement, the air heating unit further comprises a secondary air heater, a secondary air side outlet of the 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, the first working medium side outlet of the secondary air heater is connected with the working medium side inlet of the high-temperature heat storage and heat tank through a secondary air first inlet valve, and the second working medium side inlet of the secondary air heater is connected with the working medium side outlet of the high-temperature heat storage and heat storage cold tank through a secondary air second inlet valve.
As a further improvement, the third working medium side outlet of the secondary air heater is connected with the working medium side inlet of the high-temperature heat storage cold tank through a secondary air third inlet valve, and the fourth working medium side inlet of the secondary air heater is connected with the working medium side outlet of the high-temperature heat storage hot tank through a secondary air fourth inlet valve.
As a further improvement, a dust removing device is arranged at the tail pipe of the main flue, and a flue gas waste heat recovery unit is arranged between the denitration device and the dust removing device.
As a further improvement, the flue gas waste heat recovery unit comprises a low-temperature flue gas heat exchanger arranged in the main flue and a low-temperature heat storage tank arranged outside the main flue, a water side outlet of the heater is connected with a water side inlet of the low-temperature flue gas heat exchanger, a water side inlet of the heater is connected with a water side outlet of the low-temperature flue gas heat exchanger, and an inlet and an outlet of the low-temperature heat storage tank are connected with a water side outlet of the low-temperature flue gas heat exchanger through a heat storage heat exchange valve and a low-temperature heat exchange valve respectively.
As a further improvement, a water medium pump is arranged between the low-temperature flue gas heat exchanger and the air heater, the inlet of the water medium pump is connected with the water side outlet of the air heater, and the outlet of the water medium pump is connected with the water side inlet 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 flue gas flow direction, 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 feed water heater, the feed water heater is connected with the high-temperature heat storage unit, and when the power station unit operates under the load-lifting or high-load operation condition, the flue baffle is opened to enable flue gas to flow through the high-temperature flue gas heat exchanger and store surplus heat through the high-temperature heat storage unit so as to reduce the temperature of the flue gas in the main flue; and when the power station unit is in load reduction operation or deep peak regulation working condition, the flue baffle is closed, and the heat stored by the high-temperature heat storage unit is released to improve the inlet water temperature of the economizer through the feed water heater, so that the flue gas temperature before denitration of the main flue internal denitration device is improved.
The beneficial effects of the invention are as follows:
1) In the variable load operation or the deep peak regulation process of the power station unit, the inlet flue gas temperature of the denitration device cannot change along with the variable load operation of the power station unit, and the flue gas temperature of the denitration device is regulated to be controlled in an optimal operation temperature range between about 320 ℃ and 420 ℃ by opening or closing the flue baffle, so that the flue gas denitration efficiency is improved;
2) When the power station unit is in variable load operation, the temperature of the main flue gas is controlled within a reasonable range, and the method is beneficial to reducing the steady operation load of deep peak shaving of the unit.
Drawings
The invention will be further described with reference to the accompanying drawings, in which embodiments do not constitute any limitation of the invention, and other drawings can be obtained by one of ordinary skill in the art without inventive effort from the following drawings.
Fig. 1 is a schematic structural view of the present invention.
Detailed Description
In order to better understand the technical solutions of the present invention, the following description will be made in detail with reference to the accompanying drawings and specific embodiments, and it should be noted that, without conflict, the embodiments of the present application and features in the embodiments may be combined with each other.
Referring to fig. 1, an embodiment of the present invention provides a temperature control system for a boiler, a flue bypass 19 is connected in a main flue 18 of the boiler 1, a flue baffle 3 capable of being opened or closed is disposed between the main flue 18 and the flue bypass 19, and the flue baffle 3 can be configured to have a structure with upper and lower ends capable of being opened or closed simultaneously, so that flue gas in the main flue 18 can flow in and out conveniently. The main flue 18 is provided with the economizer 2 and the denitration device 16 according to the flue gas flow direction, and the denitration modes of the denitration device 16 include, but are not limited to: SCR denitration, SNCR denitration, PNCR denitration or SNCR+PNCR combined denitration and the like are adopted, the denitration mode adopted in the embodiment is SCR denitration, and the economizer 2 is arranged at the positions of the main flue 18 and the flue baffle 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, a water side outlet of the feed water heater 7 is connected with a water side inlet 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 the medium in the high-temperature heat storage hot tank 5 and the medium in the high-temperature heat storage cold tank 6 are molten salt. 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 heat tank 5 through a heat exchange heat tank valve 141, the working medium side outlet of the high-temperature heat storage heat tank 5 is connected with the working medium side inlet of the feedwater heater 7 through a heat tank heating valve 146, the working medium side outlet of the feedwater 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. For convenience of automatic production, a controller may be used, where the controller is respectively 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 to control opening or closing of each valve, and each valve defaults to a closed state.
When the power station unit operates under the load-lifting operation or the high-load operation condition, the controller controls the flue baffle 3 and the heat exchange heat tank valve 141 to be opened, and simultaneously controls the heat 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 stores heat into the high-temperature heat storage heat tank 5 to store redundant heat so as to reduce the temperature of the flue gas in the main flue 18. To further increase the cooling efficiency, the controller controls the cold tank heat exchange valve 142 to open, and the cold in the high temperature heat storage cold tank 6 is discharged from the flue bypass 19 to the main flue 18 via the cold tank heat exchange valve 142 and the high temperature flue gas heat exchanger 4.
When the power station unit is in load reduction operation or deep peak regulation working condition, the controller controls the flue baffle plate 3 to be closed, simultaneously controls the heating valve 146 of the hot tank to be opened, simultaneously controls the valve 144 of the heating cold tank 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 feedwater 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 system for coupling heat storage, the temperature of the inlet flue gas of the denitration device 16 cannot be changed along with the variable load operation of the power station unit in the variable load operation or the deep peak regulation process of the power station unit, and the temperature of the inlet flue gas of the denitration device 16 is regulated to be controlled in an optimal operation temperature range between about 320 ℃ and 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 within a reasonable range, which is helpful for reducing the steady operation load of the deep peak shaving of the unit.
As a further preferred embodiment, the power station unit comprises a feedwater backheating unit 13 used in variable load operation of the power station unit, the feedwater heater 7 is connected with the feedwater backheating unit 13, and specifically, the feedwater backheating unit 13 comprises a condenser, a low-temperature heater connected with the condenser, a steam generator connected with the low-temperature heater and a high-temperature heater connected with the steam generator, and an outlet of the high-temperature heater is connected with a water side inlet of the feedwater heater 7. In the load-reducing operation or the deep peak-shaving working condition of the power station unit, the water inlet temperature of the economizer 2 is increased by providing heat through the water feed heater 7 by the water feed heat recovery unit 13, and the flue gas temperature in the main flue 18 is further increased.
As a further preferable embodiment, the utility model also comprises an air heating unit used during the variable load operation of the utility model, when the utility model is in the load reducing operation or the deep peak regulation working condition, the air heating unit comprises a heater 10 and an air preheater 8, the air side inlet of the heater 10 is connected with a cold air source, the primary air side outlet of the heater 10 is connected with the primary air bin inlet of the air preheater 8, and the primary air bin outlet of the air preheater 8 is connected with the air inlet of the boiler 1. Under the working condition of load reduction operation or deep peak regulation of the unit, the temperature of the air inlet of the boiler 1 is increased through the air heater 10 and the air preheater 8, so that the temperature of inlet flue gas of the denitration device in the main flue 18 and the temperature of primary air of the boiler 1 are increased, and the stable operation load of deep peak regulation of the power station unit is reduced.
As a further preferred embodiment, the air heating unit further comprises a secondary air heater 15, the heater 10 is a secondary air heater, the secondary air outlet of the heater 10 is connected with the secondary air chamber inlet of the air preheater 8, the secondary air chamber outlet of the air preheater 8 is connected with the air inlet of the secondary air heater 15, and the air outlet of the secondary air heater 15 is connected with the air inlet of the boiler 1. Under the working conditions of load reduction operation or deep peak regulation of the unit, the temperature of the air inlet of the boiler 1 is increased through the air heater 10, the air preheater 8 and the secondary air heater 15, so that the temperature of flue gas at the inlet of the denitration device in the main flue 18 and the temperature of secondary air of the boiler 1 are increased, and the stable operation load of deep peak regulation of the power station unit is reduced.
As 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 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 to the working medium side outlet of the high-temperature heat storage and heat storage cold tank 6 through a secondary air second inlet valve 143. A controller may be used that is connected to the overgrate air first inlet valve 140 and the overgrate air second inlet valve 143, respectively, to control the opening or closing of each valve, which defaults to a closed state. Under the working condition of load-increasing operation or high-load operation of the power station unit, if the secondary air temperature of the inlet boiler 1 is too high, on the basis of opening the flue baffle 3 and the heat exchange heat tank valve 141 and the cold tank heat exchange valve 142, the secondary air second inlet valve 143 and the secondary air first inlet valve 140 are opened, part of the surplus heat of the secondary air heater 15 is recycled to the high-temperature heat storage heat tank 5 through the secondary air first inlet valve 140, and the cold quantity of the high-temperature heat storage cold tank 6 enters the secondary air heater 15 through the secondary air second inlet valve 143, so that the secondary air temperature of the boiler 1 is maintained at a reasonable level.
As 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-storage cold 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-storage hot tank 5 through a secondary air fourth inlet valve 147. A controller may be used, which is connected to the secondary air third inlet valve 145 and the secondary air fourth inlet valve 147, respectively, to control the opening or closing of each valve, and each valve defaults to a closed state. Under the working condition of load reduction operation or deep peak regulation 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 into 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 secondary air temperature of the boiler 1, meanwhile, the heating valve 146 of the hot tank is opened, and the inlet temperature of the economizer 2 is improved through the feedwater heater 7 to improve the inlet flue gas temperature of the denitration device, and the steady operation load of the deep peak regulation of the unit is reduced.
As a further preferred embodiment, a dust removing device 17 is disposed at the 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 the 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 the waste heat of the smoke in the main flue 18.
As a further preferred embodiment, 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, the medium in the low-temperature heat storage tank 12 is pressurized water, the water side outlet of the heater 10 is connected with the water side inlet of the low-temperature flue gas heat exchanger 9, the water side inlet of the heater 10 is connected with the water side outlet of the low-temperature flue gas heat exchanger 9, and the inlet and the outlet of the low-temperature heat storage tank 12 are respectively connected with the water side outlet of the low-temperature flue gas heat exchanger 9 through a heat storage heat exchange valve 148 and a low-temperature heat exchange valve 149. When the smoke discharging temperature of the main flue 18 is high, the heat storage and heat exchange valve 148 is opened, the low-temperature heat exchange valve 149 is closed, the smoke heat of the main flue 18 is absorbed through water medium, part of the smoke heat is stored in the low-temperature heat storage tank 12, and the part of the smoke heat flows into the water side inlet of the heater 10; when the temperature of the discharged smoke of the main flue 18 is low, the heat storage and 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 heater 10.
As a further preferred embodiment, a water medium pump 11 is disposed between the low-temperature flue gas heat exchanger 9 and the heater 10, an inlet of the water medium pump 11 is connected to a water side outlet of the heater 10, an outlet of the water medium pump 11 is connected to a water side inlet of the low-temperature flue gas heat exchanger 9, if the flue gas temperature of the main flue 18 is too high, the water medium flow of the flue gas waste heat recovery system is increased, and meanwhile, the heat storage and exchange valve 148 is opened to store the water absorbed by the flue gas waste heat through the temperature flue gas heat exchanger 9 into the low-temperature heat storage tank 12, so as to reduce the flue gas temperature of the main flue 18.
According to the invention, through the air heating unit and the flue gas waste heat recovery unit, when the power station unit changes load, the flue gas temperature of the main flue 18, the secondary air temperature of the boiler inlet and the exhaust gas temperature are controlled within a reasonable range, so that the denitration efficiency of 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 described herein, and therefore should not be construed as limiting the scope of the present invention.
In summary, while the above-described preferred embodiments have been described, it should be noted that although various changes and modifications can be made by those skilled in the art, it is intended that such changes and modifications be included within the scope of the present invention unless they depart from the scope of the present invention.
Claims (3)
1. The temperature control system of the boiler is characterized in that a flue bypass (19) is connected in a main flue (18) of the boiler (1), an openable or closable flue baffle (3) is arranged between the main flue (18) and the flue bypass (19), an economizer (2) and a denitration device (16) are respectively arranged in the main flue (18) according to the flue gas flow direction, 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 the high-temperature heat storage unit, and when a power station unit is operated under a load-lifting operation or a high-load operation condition, the flue baffle (3) is opened to enable flue gas in the main flue (18) to flow through the high-temperature flue gas heat exchanger (4) and store surplus heat to reduce the flue gas temperature in the main flue (18) through the high-temperature heat storage unit; when the power station unit is in load reduction operation or deep peak regulation working condition, the flue baffle (3) is closed, heat stored in the high-temperature heat storage unit is released, and the inlet water temperature of the economizer (2) is increased 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 increased;
the variable load type air heating device comprises a power station unit, and is characterized by further comprising an air heating unit used during variable load operation of the power station unit, wherein the air heating unit comprises a heater (10) and an air preheater (8), an air side inlet of the heater (10) is connected with a cold air source, a primary air side outlet of the 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 a boiler (1);
the air heating unit further comprises a secondary air heater (15), a secondary air side outlet of the warm air heater (10) is connected with a secondary air bin inlet of the air preheater (8), a secondary air bin outlet of the air preheater (8) is connected with an air side inlet of the secondary air heater (15), and an air side outlet of the secondary air heater (15) is connected with an air inlet of the boiler (1); a dust removing device (17) is arranged at the 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);
the high-temperature heat storage unit comprises a high-temperature heat storage hot tank (5) and a high-temperature heat storage cold tank (6), a working medium side outlet of the high-temperature flue gas heat exchanger (4) is connected with a working medium side inlet of the high-temperature heat storage hot tank (5) through a heat exchange hot tank valve (141), a working medium side outlet of the high-temperature heat storage hot tank (5) is connected with a working medium side inlet of the feed water heater (7) through a hot tank heating valve (146), a working medium side outlet of the feed water heater (7) is connected with a working medium side inlet of the high-temperature heat storage cold tank (6) through a heating cold tank valve (144), and a working medium side outlet of the high-temperature heat storage cold tank (6) is connected with a working medium side inlet of the high-temperature flue gas heat exchanger (4) through a cold tank heat exchange valve (142); 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 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 heat storage cold tank (6) through a secondary air second inlet valve (143); a third working medium side outlet (53) of the secondary air heater (15) is connected with a working medium side inlet of the high-temperature heat storage cold tank (6) through a secondary air third inlet valve (145), and a fourth working medium side inlet (54) of the secondary air heater (15) is connected with a working medium side outlet of the high-temperature heat storage hot tank (5) through a secondary air fourth inlet valve (147);
the flue gas waste heat recovery unit comprises a low-temperature flue gas heat exchanger (9) arranged in a 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 connected with a water side outlet of the low-temperature flue gas heat exchanger (9) through a heat storage heat exchange valve (148) and a low-temperature heat exchange valve (149) respectively.
2. A temperature control system of a boiler according to claim 1, characterized by comprising a feedwater backheating unit (13) for use in variable load operation of a power plant, wherein the outlet of the feedwater backheating unit (13) is connected to the water side inlet of a feedwater heater (7), and wherein the water side outlet of the feedwater heater (7) is connected to the water side inlet of an economizer (2).
3. A temperature control system of a boiler according to claim 1, characterized in that 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 a water side outlet of the air heater (10), and an outlet of the water medium pump (11) is connected with a water side inlet of the low temperature flue gas heat exchanger (9).
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