CN109404958B - Energy-saving synergistic anti-blocking method and system based on bypass flue of air preheater - Google Patents

Energy-saving synergistic anti-blocking method and system based on bypass flue of air preheater Download PDF

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Publication number
CN109404958B
CN109404958B CN201811337021.7A CN201811337021A CN109404958B CN 109404958 B CN109404958 B CN 109404958B CN 201811337021 A CN201811337021 A CN 201811337021A CN 109404958 B CN109404958 B CN 109404958B
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bypass
air
flue
blocking
outlet
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CN109404958A (en
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韦红旗
石伟伟
申先念
王丽丽
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Nanjing Bowo Science & Technology Development Co ltd
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Nanjing Bowo Science & Technology Development Co ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
    • F23L15/00—Heating of air supplied for combustion
    • F23L15/02—Arrangements of regenerators
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J15/00—Arrangements of devices for treating smoke or fumes
    • F23J15/08—Arrangements of devices for treating smoke or fumes of heaters
    • 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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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Chimneys And Flues (AREA)
  • Air Supply (AREA)
  • Treating Waste Gases (AREA)

Abstract

The invention discloses an energy-saving synergistic anti-blocking method and system based on an air preheater bypass flue. The energy-saving synergistic anti-blocking method based on the bypass flue of the air preheater is characterized in that the bypass hot flue gas heats air to a temperature above the acid dew point temperature of the flue gas, and then the air is sent to the cold end of the air preheater and independently flows through the heat storage element to prevent the ash blocking of the heat storage element. The invention heats air by the bypass hot flue gas to prevent blockage, effectively overcomes the defects existing in the prior art of using hot air circulation to prevent blockage, has the remarkable advantages of reducing the exhaust gas temperature, reducing the power consumption of factories, reducing the maintenance workload and the like, further solves the problems of zero discharge of desulfurization wastewater and stack relief Bai Dengxiang, generates a synergistic effect, reduces the total investment cost, and improves the operation safety, environmental protection and economy of a boiler flue gas system; the energy-saving synergistic anti-blocking system based on the bypass flue of the air preheater has the advantages of low operation energy consumption, stable and reliable operation, small maintenance workload and good anti-blocking effect of the air preheater.

Description

Energy-saving synergistic anti-blocking method and system based on bypass flue of air preheater
Technical Field
The invention relates to an energy-saving synergistic anti-blocking method and system based on an air preheater bypass flue, and belongs to the technical field of comprehensive optimization of auxiliary systems of power station boilers.
Background
A rotary air preheater (abbreviated as "air preheater") is a heat exchange device for a large power station boiler, which heats air required for combustion by using heat of boiler flue gas, thereby improving efficiency of the boiler. After passing through the air preheater, the flue gas temperature is generally cooled from 300-400 ℃ to 100-150 ℃, and the corresponding air temperature is generally heated from 0-50 ℃ to 280-380 ℃.
The air preheater utilizes the rotor of loading the heat storage element to continuously rotate, realizes the continuous heat absorption of the air side and the continuous heat release of the flue gas side, and the air side sub-bin can be further divided into a primary air sub-bin and a secondary air sub-bin according to the requirements of a boiler fuel system, and correspondingly, the flue gas side is driven by a draught fan to flow, and the air side is driven by a primary fan and a blower to flow.
The focus of air preheater mainly includes ash blocking, high air leakage rate, low heat transfer efficiency and serious low temperature corrosion, excessive exhaust temperatures, etc., which have long affected the safe and economical operation of the air preheater and the entire boiler system.
The above problems have long been known and are mutually promoted and mutually influenced. In recent years, with the common operation of a denitration system, the operation environment of the air preheater is changed, and the problems of ash blocking and excessive exhaust temperature become particularly remarkable, so that the treatment is difficult and complicated.
The flue gas denitration facilities added in the coal-fired power plant mainly adopt a Selective Catalytic Reduction (SCR) technology. After SCR denitration technology is adopted, part of SO in the flue gas 2 Oxidation by denitration catalyst to SO 3 Increase SO in flue gas 3 Together with the unavoidable ammonia slip, resulting in ammonium bisulfate (NH) 4 HSO 4 ) And a large amount of byproducts are generated, the acid dew point temperature of the flue gas is increased, and the low-temperature corrosion is aggravated.
The by-product ammonium bisulfate (NH) 4 HSO 4 ) In the temperature range of 146-207 ℃, the heat storage element is in a molten state and can be firmly adhered to the surface of the heat storage element of the air preheater, so that the heat storage element is corroded and deposited with ash, and finally, the ash blocking is easy to cause, thereby causing great hidden trouble for the safe operation of a unit. Some of the domestic power plants cannot solve or alleviate the problem, so that the load of the machine set is limited, and even the machine set is forced to be stopped.
When the exhaust temperature is lower than the acid dew point, the sulfuric acid vapor is condensed, sulfuric acid drops are attached to the cold end heat storage element, and the heat storage element is corroded. Acid dew point of flue gas with SO 3 The concentration is increased by increasing, generally 130 to 160 ℃. Due to the addition of SO by the denitration system 2 To SO 3 Conversion rate of SO in flue gas is improved 3 In order to control the power generation cost, the sulfur content of the actual coal is generally higher than that of the designed coal, so that the acid dew point of the current power plant is higher than the exhaust gas temperature, thereby causing the aggravation of low-temperature corrosion (acid dew point corrosion) and quite remarkable ash blocking problem.
In order to solve the ash blocking problem of the air preheater, a new technology for heating the cold end heat storage element by using hot air circulation and establishing local high flow rate anti-blocking is raised in the technical field in recent years, as disclosed in patent number 201721510369.2. The technology can effectively solve the ash blocking problem of the air preheater, but the newly added heat circulation fan has higher power consumption, and the maintenance workload is relatively larger because of being in a high-temperature and dust environment for a long time, and simultaneously, the exhaust gas temperature of the boiler is increased because of the effect of hot air circulation (compared with the condition that the air preheater is not blocked with ash, the exhaust gas temperature is increased, and if compared with the condition that the air preheater is blocked with serious ash, the exhaust gas temperature is reduced).
In addition, along with the gradual improvement of environmental protection requirements, the negative effect brought by deep removal of NOx on the air preheater is larger and larger, and the deep consideration of industry policies such as zero emission of desulfurization wastewater of a coal-fired unit, and whitening of a chimney is combined, so that a flue gas system of a coal-fired boiler of a future power station is more and more complex, and the reasonable utilization of tail flue gas heat becomes a focus of attention of the industry.
For example, in the zero-emission process of desulfurization waste water, the concentrated waste water is generally evaporated by utilizing the heat of boiler flue gas, and the desulfurization waste water is sprayed into an air preheater main flue or into an air preheater bypass flue which is independently arranged; because the serious flue corrosion risk is possibly brought by spraying the flue gas into the main flue, the new bypass flue is generally selected to evaporate desulfurization waste water, and because the high-temperature flue gas of the air preheater is directly used, the high-grade heat loss is larger, the flue gas outlet temperature of the air preheater also becomes lower, the ash blocking problem of the corresponding air preheater becomes more prominent, and the defects are more.
In summary, the ash blocking problem of the current air preheater is outstanding, and a plurality of derivative problems brought by the improvement of the environmental protection requirement are needed to be solved by a new technology.
Disclosure of Invention
The invention provides an energy-saving synergistic anti-blocking method and system based on an air preheater bypass flue, which aims to solve a series of problems existing in the prior boiler flue system with improved environmental protection requirements.
In order to solve the technical problems, the invention adopts the following technical scheme:
the energy-saving synergistic anti-blocking method based on the bypass flue of the air preheater is characterized in that the bypass hot flue gas heats air to a temperature above the acid dew point temperature of the flue gas, and then the air is sent to the cold end of the air preheater and independently flows through the heat storage element to prevent ash blocking of the heat storage element.
The bypass hot flue gas is led out through the bypass. As a general knowledge, one axial end of the air preheater is a hot end, and the other axial end is a cold end.
The air is heated by the bypass hot flue gas to prevent blockage, so that the defect of blockage prevention by using hot air circulation in the prior art is effectively overcome, and the device has the remarkable advantages of reducing the exhaust gas temperature, reducing the power consumption of factories, reducing the maintenance workload and the like.
In order to realize comprehensive utilization of heat of the bypass hot flue gas, the air is heated to 220-250 ℃ by the bypass hot flue gas, and the bypass hot flue gas is cooled to 220-150 ℃ by the air. Thus, after the bypass hot flue gas is cooled by air, the desulfurization waste water, the heating medium water and the like can be better evaporated.
Preferably, the desulfurization waste water is atomized and then sprayed into bypass hot flue gas after heating air for evaporation. Thus, not only the energy of the bypass hot flue gas is more fully utilized, but also the problem of ash blockage aggravation caused by evaporation of desulfurization waste water in the prior art is solved; in addition, the flow of bypass hot flue gas is relatively large, and the problem of corrosion of the wall surface adhered with the crystalline salt of the desulfurization wastewater is not easy to occur.
In order to further utilize the heat of the bypass hot flue gas, the bypass hot flue gas after heating air is used for heating medium water, and the heated medium water is circulated to a chimney inlet for heating the flue gas, so that the whitening of the chimney is realized.
The bypass hot flue gas is led out from the inlet main flue of the air preheater.
An energy-saving synergistic anti-blocking system based on a bypass flue of an air preheater comprises the air preheater, an inlet main flue, an outlet main flue and an anti-blocking ash bin which are arranged on the air preheater, and also comprises a bypass anti-blocking ash fan, a bypass heat exchanger, a bypass inlet flue, a bypass outlet flue, a bypass inlet flue and a bypass outlet flue;
the bypass heat exchanger comprises a heater air side channel and a heater flue gas side channel; the inlet main flue, the bypass inlet flue, the heater flue gas side channel, the bypass outlet flue and the outlet main flue are sequentially communicated; the bypass anti-blocking ash blower outlet, the bypass inlet air channel, the heater air side channel and the bypass outlet air channel are sequentially communicated, one end of the bypass outlet air channel is communicated with the heater air side channel, and the other end of the bypass outlet air channel is communicated with the anti-blocking ash bin inlet; an outlet of the anti-blocking ash bin is communicated with the outlet main air duct; the inlet of the bypass anti-blocking ash fan is communicated with the atmosphere or the inlet main air duct.
The bypass heat exchanger is preferably a dividing wall type heater for saving investment and reducing maintenance workload; to save space in the field, the bypass heat exchanger is preferably a storage heater.
The bypass inlet flue is led out from the inlet main flue of the air preheater, is sequentially connected with the heater flue gas side channel and the bypass outlet flue, and is led to the outlet main flue.
The applicant finds that by adopting the technical scheme, compared with the method for realizing the anti-ash blocking of the air preheater by adopting a hot air circulation technology, the method has no adverse effect on heat exchange caused by hot air recirculation, and the working medium of the anti-ash blocking fan is normal-temperature air, so that the method has the remarkable advantages of reducing the exhaust gas temperature, reducing the power consumption of factories, reducing the maintenance workload and the like.
In order to further utilize the heat of the flue gas flowing through the bypass outlet flue, preferably, the desulfurization waste water is atomized and then sprayed into the bypass outlet flue for evaporation.
In order to further utilize the heat of the flue gas flowing through the bypass outlet flue, as another preferable mode, a gas-water heat exchanger is added in the bypass outlet flue, and after the medium water absorbs the waste heat of the flue gas, the flue gas is sent to a chimney inlet to heat the flue gas under the driving action of a hot water circulating pump, so that the whitening of the chimney is realized.
The applicant finds that the bypass flue established for realizing the anti-blocking of the air preheater has wider potential application value, and the ratio adjustment of the bypass flue gas to air is not limited by the combustion of the boiler, so that the flue gas with proper temperature and proper flow rate is easy to obtain, thereby meeting the actual application requirements such as zero discharge of desulfurization waste water or whitening of a chimney; meanwhile, the bypass exhaust gas temperature is adjustable, and the adverse effects of the problems of ash blocking and corrosion of the bypass can be greatly relieved and even eliminated by periodically and rapidly improving the bypass exhaust gas temperature, so that the guarantee is provided for the heat utilization value of the deeply excavated bypass exhaust gas. In a word, the flexible use of the bypass flue and the integrated application of the bypass flue and various technologies have remarkable energy-saving and efficiency-improving advantages.
For the convenience of on-site arrangement, the inlet of the bypass anti-blocking ash fan is preferably communicated with the atmosphere.
In order to save the electricity consumption of the anti-ash blocking fan, preferably, the inlet of the bypass anti-ash blocking fan is communicated with the inlet main air duct through the bypass connecting air duct.
Preferably, the inlet main air duct comprises a cold primary air duct and a cold secondary air duct, the outlet main air duct comprises a hot primary air duct and a hot secondary air duct, and the air preheater comprises a primary air sub-bin and a secondary air sub-bin; the cold primary air duct, the primary air sub-bin and the hot primary air duct are sequentially communicated, and the cold secondary air duct, the secondary air sub-bin and the hot secondary air duct are sequentially communicated; the anti-blocking ash bin is positioned between the primary air bin and the secondary air bin, and an outlet of the anti-blocking ash bin is communicated with the hot primary air duct or the hot secondary air duct.
When the primary air allowance required by the boiler is less than 10%, preferably, the anti-blocking ash bin outlet is communicated with the hot primary air duct; when the required overgrate air allowance of the boiler is less than 10%, the anti-blocking ash bin outlet is preferably communicated with the hot overgrate air channel.
In order to reduce the risk of ash blocking of the bypass heat exchanger, preferably, the bypass heat exchanger is of a vertical pipe structure, flue gas is introduced into the pipe, and air is introduced into the pipe.
In order to adjust the air output of the anti-ash blocking fan in a more economical way, the bypass anti-ash blocking fan is preferably driven by a motor and controlled in a variable frequency manner.
In order to adjust the flow of the bypass flue gas, preferably, a bypass flue gas baffle door is arranged on the bypass inlet flue and/or the bypass outlet flue, and the opening of the bypass flue gas baffle door is adjusted to change the flow of the bypass flue gas.
For convenient isolation and overhaul of the bypass heat exchanger, preferably, the bypass inlet flue and the bypass outlet flue are respectively provided with a bypass flue gas baffle door or a bypass flue gas isolation door, and the bypass outlet flue is provided with a bypass air isolation door. The isolation door has only an opening and closing function, and the opening of the baffle door can be adjusted, so that the flue gas flow is adjusted.
In order to improve the cost performance of the integrated application of the anti-blocking and desulfurization wastewater zero-emission or chimney whitening technology of the air preheater, the method comprises the steps of optimizing initial investment and operation cost, heating the bypass air to 220-250 ℃ after passing through a bypass heat exchanger, and cooling the bypass flue gas to 220-150 ℃.
The bypass air is air introduced by the bypass anti-blocking ash blower, and the bypass flue gas is flue gas entering the flue gas side channel of the heater.
The structural features of the anti-blocking ash bin are not repeated, and are repeatedly explained in patent documents related to anti-blocking ash of the air preheater disclosed before the applicant, such as patents or patent applications with application numbers 201510369487.5, 201710698879.5, 201721019416.3, 201721321397.X, 201711234268.1, 201721510369.2 and the like.
The technology not mentioned in the present invention refers to the prior art.
The energy-saving synergistic anti-blocking method based on the bypass flue of the air preheater, disclosed by the invention, has the advantages of effectively overcoming the defects of the existing anti-blocking method by utilizing hot air circulation by heating air by the bypass hot flue gas, reducing the exhaust gas temperature, reducing the power consumption of factories, reducing the maintenance workload and the like, and further solves the problems of zero emission of desulfurization wastewater and stack removal Bai Dengxiang; the energy-saving synergistic anti-blocking system based on the bypass flue of the air preheater has the advantages of small operation energy consumption, stable and reliable operation, small maintenance workload and good anti-blocking effect of the air preheater, and further, the bypass flue is convenient to use and integrate technologies such as zero discharge of desulfurization wastewater, whitening of a chimney and the like, a synergistic effect is generated, the total investment cost is reduced, and the operation safety, environmental protection and economy of the boiler air-smoke system are improved.
Drawings
FIG. 1 is a schematic diagram of a system according to embodiment 1 of the present invention.
Fig. 2 is a schematic diagram of a system according to embodiment 2 of the present invention.
Fig. 3 is a schematic diagram of a system according to embodiment 3 of the present invention.
Fig. 4 is a schematic diagram of a system in embodiment 4 of the present invention.
FIG. 5 is an embodiment of the present invention example 5 schematic system diagram.
In the figure: 1 is an inlet main flue, 2 is an outlet main flue, 3 is an inlet main flue, 4 is an outlet main flue, 5 is a bypass anti-blocking ash blower, 6 is a bypass heat exchanger, 7 is a bypass inlet flue, 8 is a bypass outlet flue, 9 is a bypass inlet flue, 10 is a bypass outlet flue, 11 is an anti-blocking ash bin, and 12 is a bypass connecting flue; 20 is a bypass smoke baffle door, 21 is a bypass smoke isolation door, and 22 is a bypass air isolation door; 30 is desulfurization wastewater, 31 is a gas-water heat exchanger, 32 is a hot water circulating pump, and 33 is a chimney; 100 is an air preheater heat storage element, 101 is an air preheater flue gas side flow direction, 102 is an air preheater air side flow direction, 103 is a bypass flue gas flow direction, and 104 is a bypass air flow direction.
Detailed Description
For a better understanding of the present invention, the following examples are further illustrated, but are not limited to the following examples.
Example 1
The energy-saving synergistic anti-blocking method based on the bypass flue of the air preheater is characterized in that the bypass hot flue gas heats air to a temperature above the acid dew point temperature of the flue gas, and then the air is sent to the cold end of the air preheater and independently flows through the heat storage element to prevent ash blocking of the heat storage element.
The air is heated by the bypass hot flue gas to prevent blockage, so that the defect of blockage prevention by using hot air circulation in the prior art is effectively overcome, and the device has the remarkable advantages of reducing the exhaust gas temperature, reducing the power consumption of factories, reducing the maintenance workload and the like.
As shown in fig. 1, the energy-saving synergistic anti-blocking system based on the bypass flue of the air preheater for realizing the method comprises the air preheater, an inlet main flue, an outlet main flue and an anti-blocking ash bin which are arranged on the air preheater, and further comprises a bypass anti-blocking ash fan, a bypass heat exchanger, a bypass inlet flue, a bypass outlet flue, a bypass inlet flue and a bypass outlet flue;
the bypass heat exchanger is a partition wall type heater and comprises a heater air side channel and a heater flue gas side channel; the inlet main flue, the bypass inlet flue, the heater flue gas side channel, the bypass outlet flue and the outlet main flue are sequentially communicated; the bypass anti-blocking ash blower outlet, the bypass inlet air channel, the heater air side channel and the bypass outlet air channel are sequentially communicated, one end of the bypass outlet air channel is communicated with the heater air side channel, and the other end of the bypass outlet air channel is communicated with the anti-blocking ash bin inlet; an outlet of the anti-blocking ash bin is communicated with the outlet main air duct; the inlet of the bypass anti-blocking ash blower is communicated with the atmosphere, so that the on-site arrangement is convenient.
The bypass inlet flue is led out from the inlet main flue of the air preheater, is sequentially connected with the heater flue gas side channel and the bypass outlet flue, and is led to the outlet main flue.
The applicant finds that by adopting the technical scheme, compared with the method for realizing the anti-ash blocking of the air preheater by adopting a hot air circulation technology, the method has no adverse effect on heat exchange caused by hot air recirculation, and the working medium of the anti-ash blocking fan is normal-temperature air, so that the method has the remarkable advantages of reducing the exhaust gas temperature, reducing the power consumption of factories, reducing the maintenance workload and the like.
In the embodiment, the energy-saving synergistic anti-blocking system based on the bypass flue of the air preheater is put into operation, the exhaust gas temperature is reduced by about 5 ℃, the air supply of the bypass anti-blocking ash blower is heated to about 280 ℃ by the bypass heat exchanger and then is sent into the anti-blocking ash separation bin, and the resistance of the air preheater is always kept not to rise.
Example 2
As shown in fig. 2, substantially the same as in example 1, except that: for the convenience keep apart and overhaul bypass heat exchanger, adjust the flow of bypass flue gas simultaneously, be equipped with bypass flue gas baffle door on the bypass entry flue, be equipped with bypass flue gas isolation door on the bypass exit flue, bypass exit wind channel sets up bypass air isolation door.
Example 3
As shown in fig. 3, substantially the same as in example 1 except that: in order to save the electricity consumption of the anti-blocking ash blower, the inlet of the bypass anti-blocking ash blower is communicated with the inlet main air duct through the bypass connecting air duct.
Example 4
As shown in fig. 4, basically the same as in example 1, except that: in order to realize the comprehensive utilization of the heat of the bypass hot flue gas, the bypass air temperature is heated to 220-250 ℃ after passing through a bypass heat exchanger, and the bypass flue gas temperature is cooled to 220-150 ℃; and atomizing the desulfurization wastewater, and spraying the atomized desulfurization wastewater into bypass hot flue gas after heating air for evaporation. Thus, not only the energy of the bypass hot flue gas is more fully utilized, but also the problem of ash blockage aggravation caused by evaporation of desulfurization waste water in the prior art is solved; in addition, the flow of bypass hot flue gas is relatively large, and the problem of corrosion of the wall surface adhered with the crystalline salt of the desulfurization wastewater is not easy to occur.
Example 5
As shown in fig. 5, basically the same as in example 1, except that: in order to further utilize the heat of the flue gas flowing through the bypass outlet flue, the energy-saving synergistic anti-blocking system based on the bypass flue of the air preheater further comprises a gas-water heat exchanger and a hot water circulating pump, and the medium water absorbs heat in the bypass outlet flue and releases heat in the chimney inlet flue through the gas-water heat exchanger under the driving action of the hot water circulating pump, so that the whitening of the chimney is realized.
Example 6
Substantially the same as in example 1, except that: the inlet main air duct comprises a cold primary air duct and a cold secondary air duct, the outlet main air duct comprises a hot primary air duct and a hot secondary air duct, and the air preheater comprises a primary air sub-bin and a secondary air sub-bin; the cold primary air duct, the primary air sub-bin and the hot primary air duct are sequentially communicated, and the cold secondary air duct, the secondary air sub-bin and the hot secondary air duct are sequentially communicated; the anti-blocking ash separation bin is positioned between the primary air separation bin and the secondary air separation bin, the outlet of the anti-blocking ash bin is communicated with the hot primary air duct or the hot secondary air duct. When the primary air allowance required by the boiler is less than 10%, the outlet of the anti-blocking ash bin is communicated with the hot primary air duct; when the allowance of the secondary air required by the boiler is less than 10%, the outlet of the anti-blocking ash bin is communicated with the hot secondary air channel.
In order to reduce the ash blocking risk of the bypass heat exchanger, the bypass heat exchanger is of a vertical pipe structure, flue gas is communicated in the pipe, and air is communicated outside the pipe. In order to regulate the air output of the anti-ash blocking blower in a more economical way, the bypass anti-ash blocking blower is driven by a motor and controlled in a variable frequency manner.
Example 7
Substantially the same as in example 1, except that: for the air preheater with three or four sub-bins, in order to save the power consumption of the anti-blocking ash blower and improve the allowance of secondary air, the inlet of the bypass anti-blocking ash blower is communicated with the cold secondary air channel through the bypass connecting air channel, and the outlet of the corresponding anti-blocking ash bin is communicated with the hot secondary air channel.
Example 8
Substantially the same as in example 1, except that: for the air preheater with three or four sub-bins, in order to save the power consumption of the ash blocking prevention fan and improve the primary air margin, the inlet of the bypass ash blocking prevention fan is communicated with the cold secondary air channel through the bypass connecting air channel, and the outlet of the corresponding ash blocking prevention bin is communicated with the hot primary air channel.
Example 9
Substantially the same as in example 1, except that: for the air preheater with three or four sub-bins, in order to save the power consumption of the ash blocking prevention fan and improve the primary air margin, the inlet of the bypass ash blocking prevention fan is communicated with the cold primary air channel through the bypass connecting air channel, and the outlet of the corresponding ash blocking prevention bin is communicated with the hot primary air channel.
Example 10
Substantially the same as in example 1, except that: for a large-scale coal-fired unit, in order to save the field arrangement space, the bypass heat exchanger is a heat accumulating heat exchanger, in particular to a bypass two-bin rotary structure, and heat of bypass hot flue gas is conducted to bypass air through rotation.
The applicant finds that the bypass flue established for realizing the anti-blocking of the air preheater has wider potential application value, and the ratio adjustment of the bypass flue gas to air is not limited by the combustion of the boiler, so that the flue gas with proper temperature and proper flow rate is easy to obtain, thereby meeting the actual application requirements such as zero discharge of desulfurization waste water or whitening of a chimney; meanwhile, the bypass exhaust gas temperature is adjustable, and the adverse effects of the problems of ash blocking and corrosion of the bypass can be greatly relieved and even eliminated by periodically and rapidly improving the bypass exhaust gas temperature, so that the guarantee is provided for the heat utilization value of the deeply excavated bypass exhaust gas. In a word, the flexible use of the bypass flue and the integrated application of the bypass flue and various technologies have remarkable energy-saving and efficiency-improving advantages.

Claims (5)

1. The utility model provides an energy-conserving efficiency-increasing anti-blocking system based on air heater bypass flue, includes air heater and establishes entry main flue, export main flue, entry main flue, export main flue and anti-blocking ash bin on air heater, its characterized in that: the device also comprises a bypass anti-blocking ash fan, a bypass heat exchanger, a bypass inlet flue, a bypass outlet flue, a bypass inlet air flue and a bypass outlet air flue;
the bypass heat exchanger comprises a heater air side channel and a heater flue gas side channel; the inlet main flue, the bypass inlet flue, the heater flue gas side channel, the bypass outlet flue and the outlet main flue are sequentially communicated; the bypass anti-blocking ash blower outlet, the bypass inlet air channel, the heater air side channel and the bypass outlet air channel are sequentially communicated, one end of the bypass outlet air channel is communicated with the heater air side channel, and the other end of the bypass outlet air channel is communicated with the anti-blocking ash bin inlet; an outlet of the anti-blocking ash bin is communicated with the outlet main air duct; the inlet of the bypass anti-blocking ash fan is communicated with the atmosphere or an inlet main air duct;
the inlet of the bypass anti-blocking ash fan is communicated with the inlet main air duct through the bypass connecting air duct;
the bypass heat exchanger is of a vertical pipe structure, smoke is introduced into the pipe, and air is introduced into the pipe.
2. The energy-saving and efficiency-increasing anti-blocking system based on the bypass flue of the air preheater as set forth in claim 1, wherein: and spraying the atomized desulfurization wastewater into a bypass outlet flue for evaporation.
3. The energy-saving and efficiency-increasing anti-blocking system based on the bypass flue of the air preheater as set forth in claim 1, wherein: and a gas-water heat exchanger is added in the bypass outlet flue, and after the medium water absorbs the waste heat of the flue gas, the flue gas is sent to a chimney inlet to heat the flue gas under the driving action of a hot water circulating pump, so that the whitening of the chimney is realized.
4. The energy-saving and efficiency-increasing anti-blocking system based on the bypass flue of the air preheater as set forth in any one of claims 1-3, wherein: the inlet main air duct comprises a cold primary air duct and a cold secondary air duct, the outlet main air duct comprises a hot primary air duct and a hot secondary air duct, and the air preheater comprises a primary air sub-bin and a secondary air sub-bin; the cold primary air duct, the primary air sub-bin and the hot primary air duct are sequentially communicated, and the cold secondary air duct, the secondary air sub-bin and the hot secondary air duct are sequentially communicated; the anti-blocking ash bin is positioned between the primary air bin and the secondary air bin, and an outlet of the anti-blocking ash bin is communicated with the hot primary air duct or the hot secondary air duct.
5. The energy-saving and efficiency-increasing anti-blocking system based on the bypass flue of the air preheater as set forth in any one of claims 1-3, wherein: the bypass inlet flue and the bypass outlet flue are respectively provided with a bypass flue gas baffle door or a bypass flue gas isolation door, and the bypass outlet flue is provided with a bypass air isolation door.
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