CN209782699U - System for preventing dust deposition and contamination of rotary air preheater - Google Patents
System for preventing dust deposition and contamination of rotary air preheater Download PDFInfo
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- CN209782699U CN209782699U CN201920649222.4U CN201920649222U CN209782699U CN 209782699 U CN209782699 U CN 209782699U CN 201920649222 U CN201920649222 U CN 201920649222U CN 209782699 U CN209782699 U CN 209782699U
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- 230000008021 deposition Effects 0.000 title claims abstract description 39
- 239000000428 dust Substances 0.000 title claims description 37
- 238000011109 contamination Methods 0.000 title description 13
- 238000010438 heat treatment Methods 0.000 claims abstract description 88
- 239000003546 flue gas Substances 0.000 claims abstract description 50
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims abstract description 48
- 238000005192 partition Methods 0.000 claims abstract description 26
- 238000000605 extraction Methods 0.000 claims abstract description 13
- 230000001105 regulatory effect Effects 0.000 claims description 32
- 239000000779 smoke Substances 0.000 claims description 22
- 238000001514 detection method Methods 0.000 claims description 11
- 238000004891 communication Methods 0.000 claims description 9
- 238000005086 pumping Methods 0.000 claims description 8
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 7
- 229910052760 oxygen Inorganic materials 0.000 claims description 7
- 239000001301 oxygen Substances 0.000 claims description 7
- 238000000151 deposition Methods 0.000 description 36
- BIGPRXCJEDHCLP-UHFFFAOYSA-N ammonium bisulfate Chemical compound [NH4+].OS([O-])(=O)=O BIGPRXCJEDHCLP-UHFFFAOYSA-N 0.000 description 19
- 238000005338 heat storage Methods 0.000 description 15
- 238000002485 combustion reaction Methods 0.000 description 14
- 239000000446 fuel Substances 0.000 description 14
- 239000012530 fluid Substances 0.000 description 12
- 239000003245 coal Substances 0.000 description 11
- 230000000694 effects Effects 0.000 description 11
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 8
- 239000002956 ash Substances 0.000 description 8
- 238000013461 design Methods 0.000 description 8
- 238000005260 corrosion Methods 0.000 description 7
- 230000007797 corrosion Effects 0.000 description 7
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 6
- 238000009826 distribution Methods 0.000 description 6
- 238000001035 drying Methods 0.000 description 6
- 238000010298 pulverizing process Methods 0.000 description 6
- 238000007789 sealing Methods 0.000 description 6
- 238000012546 transfer Methods 0.000 description 6
- AKEJUJNQAAGONA-UHFFFAOYSA-N sulfur trioxide Chemical compound O=S(=O)=O AKEJUJNQAAGONA-UHFFFAOYSA-N 0.000 description 5
- 238000007664 blowing Methods 0.000 description 4
- 239000010881 fly ash Substances 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 229910021529 ammonia Inorganic materials 0.000 description 3
- 238000012544 monitoring process Methods 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 230000002265 prevention Effects 0.000 description 3
- 238000011084 recovery Methods 0.000 description 3
- 238000010186 staining Methods 0.000 description 3
- 229910052717 sulfur Inorganic materials 0.000 description 3
- 239000011593 sulfur Substances 0.000 description 3
- 239000002918 waste heat Substances 0.000 description 3
- 239000002253 acid Substances 0.000 description 2
- 239000003054 catalyst Substances 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 210000003298 dental enamel Anatomy 0.000 description 2
- 238000005485 electric heating Methods 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000002360 explosive Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000003801 milling Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 239000004071 soot Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000010977 unit operation Methods 0.000 description 2
- WWILHZQYNPQALT-UHFFFAOYSA-N 2-methyl-2-morpholin-4-ylpropanal Chemical compound O=CC(C)(C)N1CCOCC1 WWILHZQYNPQALT-UHFFFAOYSA-N 0.000 description 1
- 235000001674 Agaricus brunnescens Nutrition 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000002803 fossil fuel Substances 0.000 description 1
- 239000002737 fuel gas Substances 0.000 description 1
- 239000000295 fuel oil Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000002309 gasification Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000003077 lignite Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
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Classifications
-
- 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 utility model discloses a system for prevent rotary air heater deposition from staiing, be formed with the flue gas including inside and divide the air heater in storehouse, once wind branch storehouse and overgrate air branch storehouse, the flue gas divides and keeps apart through first baffle between storehouse and the once wind branch storehouse, the flue gas divides the storehouse and the overgrate air divides to keep apart through the second baffle between the storehouse, the overgrate air divides to separate out through the third baffle in the storehouse and adds hot air storehouse, its characterized in that: the first partition plate and/or the second partition plate positioned at the hot end of the air preheater are/is provided with air extraction holes communicated with a radial air leakage gap at the hot end of the air preheater, the air extraction holes are communicated with an air inlet duct of the heating air bin through an air leakage extraction pipeline, and an air outlet duct of the heating air bin is connected to a negative pressure fan; the heating air bin is arranged at the hot end of the air preheater, and the heating air bin is arranged at the cold end of the air preheater. The utility model discloses can solve traditional rotary air heater deposition and stain and leak the problem that wind can not make full use of.
Description
Technical Field
The utility model belongs to the technical field of boiler air heater, especially, relate to a system for prevent that rotation air heater deposition from staiing.
Background
the rotary air preheater is widely applied to large power station boilers, heats air required by fuel combustion by using heat of boiler combustion smoke, and has the effects of improving combustion efficiency and recovering waste heat of the smoke. The rotary air preheater of the large power station boiler usually adopts a three-divided bin and four-divided bin structure design, namely, the through-flow section of a rotor is divided into a flue gas divided bin, a primary air divided bin and a secondary air divided bin, and sector plates with certain angles are respectively radially adopted at a hot end and a cold end to separate different fluid divided bins.
Air leakage is a significant problem in the operation of air preheaters, including direct air leakage and carryover air leakage. The air pressure in the air preheater is higher than the flue gas pressure, so that the air leaks to the flue gas side, namely direct air leakage; as the air preheater rotor rotates, air is carried to the flue gas side, referred to as carry over leakage. The direct air leakage rate is related to the sealing gap and the fluid pressure difference, and the larger the gap and the pressure difference are, the larger the direct air leakage rate is; the carrying air leakage rate is related to the volume and the rotating speed of the rotor, and after the structure of the air preheater is determined, the carrying air leakage rate is basically determined.
When the rotary air preheater operates, as the temperature of a hot end element is higher than that of a cold end element, the expansion amount of the rotor is large, the rotor is deformed like a mushroom, a triangular air leakage gap at the cold end of the rotor and an axial air leakage gap in the circumferential direction of the rotor are smaller than those in a cold state, and an air leakage gap at the hot end of the rotor is larger than those in the cold state. Therefore, the proportion of the hot end air leakage of the rotor is the largest in each air leakage. Under the rated load working condition of the unit, the deformation of the rotor reaches the maximum, and at the moment, more than 60 percent of air leakage quantity is leaked from the hot end radial air leakage gap.
The hot end air leakage is different from the cold end air leakage, and the leaked high-temperature air is preheated, and the part of air is mixed with the flue gas and then flows through the air preheater rotor again, so that the heat exchange efficiency of the air preheater is reduced, the smoke discharge loss of a boiler is increased, and the power consumption rate of a unit fan is increased. The effective control air preheater leaks out, especially hot junction leaks out, becomes the focus of each producer's research and improvement. The flexible sealing technology has the problems of structural member abrasion, low reliability and the like, and is not widely accepted in the industry all the time; an air Leakage Control System (LCS) is influenced by factors such as high temperature, dust and other severe working conditions, maintenance quality, management level and the like, and the operation failure rate is usually higher.
In the aspect of reducing the gasket both sides pressure differential, the current double containment, three sealed designs of generally adopting (that is the sector plate covers twice or three sealings at least, and its angle is rotor compartment angle or triple), the increase of sealing area angle, the branch storehouse angle of participating in the heat transfer reduces, under the prerequisite of guaranteeing heat transfer volume, heat exchange efficiency and circulation resistance, must increase air heater volume, leads to the equipment investment cost to increase.
Another significant problem in the operation of rotary air preheaters is the ash deposition and contamination of the internal heat storage elementsAnd (6) depositing. The combustion products of fossil fuels typically contain sulfur trioxide (SO)3) And water vapor (H)2O) both, SO3In combination with water vapor, when the flue gas is cooled to a sufficient degree inside the air preheater (when the temperature of the metal wall surface of the heat storage element filled inside the air preheater is lower than the dew point of the sulfuric acid vapor), the flue gas will be condensed into liquid sulfuric acid (H)2SO4) The strong corrosion to the metal heat storage element is formed, meanwhile, the fly ash particles in the flue gas are adhered to the surface of the heat storage element to cause scaling, and the sectional area of a gas flow channel is reduced to cause the reduction of the heat transfer efficiency of the air preheater, the increase of the flow resistance and the increase of the power consumption of a fan, thereby seriously influencing the safe and economic operation of the boiler.
The utility boiler adopting the SCR flue gas denitration technology has the advantages that on one hand, partial SO is removed under the action of the catalyst2Oxidation to SO3On the other hand, due to NH in the flue gas3The mole ratio of NO, the flow field of the flue gas and the like are affected by uneven distribution, and a small amount of unreacted reducing agent NH escaping from the flue gas at the downstream of the catalyst inevitably exists3And with SO in flue gas3、H2O and the like react to generate Ammonium Bisulfate (ABS), the substance begins to condense in the temperature range of about 150-200 ℃, and is generally positioned in the bottom and low temperature range of the medium temperature section of the air preheater of the traditional power station boiler, and the substance has strong viscosity, so that fly ash is adhered to cause blockage.
Studies have shown that the ash buildup from ABS is generally more pronounced where the thermal storage elements delaminate. Meanwhile, the cold-end heat storage element is of a closed plate type, and surface deposits can be effectively removed in a regular steam soot blowing mode generally; and the surface of the ceramic is treated by an enamel plating process, so that the ceramic has higher smoothness, and better corrosion resistance and dust deposition performance compared with elements at a hot end and a medium temperature section. In summary, the region of the air preheater heat storage element ABS that is most at risk of corrosion and ash deposition is present in the bottom region of the mid-temperature stage heat storage element.
Ammonium hydrogen sulfate (ABS) and sulfuric acid vapor (H)2SO4) The corrosion deposits produced, their extent and degree, the concentration of the products of the gaseous constituents and the dew point temperature, and the direction of flow of the heat-accumulating elements along the gasThe temperature distribution in the direction of rotation of the rotor is related. The temperature distribution in the rotor is changed, the interval of the deposition product is limited in the range of the cold end element under the conditions of different environmental temperatures and unit load, the deposition product can be effectively removed by means of soot blowing and the like, and the influence of the deposition product on the unit operation is reduced to the minimum.
Ammonium Bisulfate (ABS) deposited on the surface of the heat storage element of the air preheater can generate phase change gasification above the dew point temperature, and the surface temperature of the heat storage element is periodically increased, so that the deposition products are decomposed and are stripped and carried by airflow, and the method is a 'hot cleaning' method, and is helpful for preventing the ash deposition trend from increasing.
201820677908.X discloses a rotary air preheater of a power station boiler for preventing deposition contamination, wherein a secondary air sub-bin is internally divided into a circulating heating sub-bin through a partition plate, and then through corresponding pipeline system design and arrangement, under the working condition that the deposition tendency of a rotor is low, the flow of primary air/secondary air of a partial boiler is divided, and the exhaust temperature is reduced by utilizing the countercurrent heat exchange of the secondary air/primary air of the partial boiler and flue gas; when the dust deposition tendency of the rotor is increased, the downstream flow of fluid and smoke in the circulating heating air bin is realized, heat is absorbed by the high-temperature section element, heat is released to the rotor element at the bottom of the middle-temperature section and the area where dust deposition at the low-temperature section is most difficult to remove, the temperature level is effectively improved, and then the deposition of dust deposition and contamination is greatly reduced.
SUMMERY OF THE UTILITY MODEL
The present application is directed to solving one of the technical problems in the prior art. Therefore, an object of the present invention is to provide a system for preventing deposition contamination of a rotary air preheater, so as to solve the problem that the deposition contamination and the leakage air of the conventional rotary air preheater cannot be fully utilized.
In order to solve the technical problem, the utility model adopts the following technical scheme:
A system for preventing dust deposition and contamination of a rotary air preheater comprises an air preheater, wherein a smoke sub-bin, a primary air sub-bin and a secondary air sub-bin are formed inside the air preheater, the smoke sub-bin and the primary air sub-bin are isolated by a first partition plate, the smoke sub-bin and the secondary air sub-bin are isolated by a second partition plate, a heating air bin is separated from the secondary air sub-bin by a third partition plate, an air pumping hole communicated with a radial air leakage gap at the hot end of the air preheater is formed in the first partition plate and/or the second partition plate at the hot end of the air preheater, the air pumping hole is communicated with an air inlet duct of the heating air bin through an air leakage pumping pipeline, and an air outlet duct of the heating air bin is connected to a negative pressure fan; the heating air bin is arranged at the hot end of the air preheater, and the heating air bin is arranged at the cold end of the air preheater.
Furthermore, the outlet end of the negative pressure fan is connected to the primary air sub-bin air outlet duct and the secondary air sub-bin air outlet duct through a first connecting pipeline and a second connecting pipeline respectively, a first adjusting valve and a second adjusting valve are arranged on the first connecting pipeline and the second connecting pipeline respectively, and a third adjusting valve is arranged on the air leakage pumping pipeline.
Furthermore, the first connecting pipeline and the second connecting pipeline are communicated with the negative pressure fan through a connecting main pipe with a first flow detection device and an air channel heater, and a second flow detection device is arranged on the air outlet channel of the heating air bin, close to the air outlet end of the heating air bin.
Furthermore, a communication main pipe between the first flow detection device and the air channel heater is communicated with the air inlet channel of the heating air bin through a fourth communication channel with a sixth regulating valve.
Furthermore, the second connecting pipeline is communicated with the air leakage extracting pipeline through a fourth connecting channel with a seventh regulating valve.
Furthermore, a dust removal device is further arranged on the air outlet duct of the heating air bin, and a fourth adjusting valve and a fifth adjusting valve are respectively arranged at the inlet end and the outlet end of the negative pressure fan.
furthermore, the system also comprises a pressure difference measuring instrument arranged between the air leakage extraction pipeline and the flue gas inlet flue of the smoke sub-bin.
Furthermore, the first partition plate, the second partition plate and the third partition plate are all fan-shaped plates, and the air pumping holes are uniformly distributed in rows along the radial direction of the fan-shaped plates.
Furthermore, the outlet end of the negative pressure fan is sequentially connected to the dust remover and the draught fan through a fifth connecting channel with an eighth adjusting valve, a smoke bin outlet flue is connected to the dust remover, an air outlet pipeline of the draught fan is communicated with an air outlet channel of the heating air bin through a sixth connecting channel with a ninth adjusting valve, and an oxygen concentration measuring point is arranged on the second connecting channel.
Furthermore, the air outlet duct of the heating air bin is communicated with the fifth connecting duct through a seventh connecting duct provided with a tenth adjusting valve, and the air inlet duct of the secondary air sub-bin is communicated with the air outlet duct of the heating air bin through an eighth connecting duct provided with an eleventh adjusting valve.
Compared with the prior art, the beneficial effects of the utility model reside in that:
1. In the utility model, the top of the sector plate between the primary air bin and the secondary air bin at the hot end of the air preheater and the flue gas sub-bin is provided with a hole which is connected with an air leakage suction pipeline; an independent heating air bin is arranged in a secondary air bin, a negative pressure fan and a corresponding connecting air channel are added, hot end air leakage is extracted from an opening at the top of a sector plate by driving of a pressure head at a negative pressure fan or an air side and a smoke side, and flows through an air leakage suction pipeline and enters the heating air bin from the hot end to form forward flow with smoke from the hot end to the cold end, after a medium absorbs heat storage of a hot end element, the temperature of a fluid rises, heat is released to a middle-temperature section and a cold-end heat storage element by convection heat exchange, the temperature of the element in an area (the bottom of the middle-temperature section) which is most difficult to remove accumulated dust of an air preheater is effectively increased to be higher than the dew point temperature of condensable products in smoke such as Ammonium Bisulfate (ABS), sulfuric acid vapor and the like, and the effect of preventing the. The medium after heat release flows out from the cold end of the heating air bin, fly ash particles carried in the medium are removed through the dust removal device, the pressure head is lifted by the negative pressure fan, and then the medium enters the flue at the inlet of the dust remover through a connecting pipeline according to the requirements of application occasions and system working conditions, or enters the air outlet duct of the primary air bin of the outlet of the air preheater, or enters the air outlet duct of the secondary air bin of the air preheater, or is partially recycled to the inlet of the heating air bin, so that open-type flow or closed-type circulation flow is.
2. The top of the sector plate between the hot end primary air and secondary air sub-bins and the flue gas sub-bins is provided with holes, the number of the holes is equal to the number of the element frames in the radial direction, the area and the type of the holes are determined by the intensity check of an air preheater manufacturer, hot end air leakage is led out from a suction pipeline at the positions of the holes of the sector plate, and each air leakage suction branch pipe and the main pipe are provided with flow regulating valves.
3. The single countercurrent heat exchange type of the smoke and the air of the rotary air preheater in the traditional design is changed, the fan-shaped plate is used for sealing and isolating the independent rotor heating air bin in the original air sub-bin, and the fluid in the air bin can realize the switch of the cocurrent/countercurrent with the flow direction of the smoke.
4. Through the design and arrangement of a corresponding pipeline system, a main pipe after a hot end air leakage suction pipeline is converged is connected with a hot end inlet of a heating air bin, a cold end outlet of the heating air bin is connected with an inlet of a negative pressure fan, hot end air leakage enters the heating air bin from the upper part under the suction or pressure difference between fluids of the negative pressure fan, and flows from the hot end to the cold end in the same direction as flue gas, and compared with the scheme that the hot end air leakage flows from the cold end to the hot end, the scheme can achieve the effect of heating the area with the maximum corrosion and dust deposition risk at the bottom of the medium temperature end to a larger extent, simultaneously ensure that the temperature of a cold end element is higher than the acid dew point, and the temperature of a bottom element at the medium temperature end is higher than the dew point temperature of Ammonium Bisulfate (ABS), so that the ABS is completely deposited on a large channel, a closed plate type and a.
5. The outlet of the negative pressure fan is hot air, and different recovery ways can be selected according to different unit operation conditions, coal quality for combustion and reconstruction investment: firstly, a dust remover is introduced, and because the inlet of the dust remover is negative pressure, the total pressure rise and the power of a negative pressure fan are lower; introducing an air outlet pipeline of a hot secondary air bin at the outlet of the air preheater as a part of fuel combustion air; or an air outlet pipeline of a primary air bin of the air preheater is introduced to be used as a medium for drying and conveying fuel of the pulverizing system. At the moment, air at the outlet of the negative pressure fan enters a boiler furnace to participate in combustion for utilization, so that the air flow passing through the primary air sub-bin and the secondary air sub-bin of the air preheater is reduced, the air/flue gas heat capacity ratio is reduced, and the temperature level of the rotor is further improved.
6. In order to reduce the influence of the arrangement of the heating air bin on the increase of the resistance of an original primary air/secondary air system and ensure the sufficient rotor temperature lifting effect, the nominal angle of the heating air bin is required to be as small as possible, and the flow velocity and the inlet fluid temperature of the fluid in the air bin are required to be ensured to be above a certain threshold value so as to ensure the necessary heat transfer coefficient and heat exchange effect, a medium flow velocity/flow measurement device is arranged on an air outlet duct at the cold end of the heating air bin and is used for monitoring and adjusting the flow velocity of the fluid medium in the heating air bin; on the hot end air inlet duct of the heating air bin, a temperature measuring device such as a thermal resistor/thermocouple is configured for monitoring and adjusting the temperature of the fluid entering the heating air bin.
7. In order to ensure the necessary medium flow velocity in the heating air bin, a recirculation connecting pipeline and a corresponding flow adjusting device which are connected to an air inlet channel of the heating air bin are arranged at the outlet of the negative pressure fan, so that the flow velocity of the fluid in the heating air bin is ensured to be above a threshold value under different working conditions; in order to meet the requirement of preventing dust deposition and contamination of an air preheater under different coal qualities and load conditions, a heater adopting steam heating/electric heating is arranged on an outlet of a negative pressure fan so as to ensure the temperature level of the recirculated hot air of a heating air bin and improve the temperature to the air temperature of a hot secondary air box under the working conditions of low-load operation of a unit and low-volatile-component burning of inferior coal; when high-moisture coal types such as brown coal are combusted by the unit, the air temperature of the hot primary air main pipe at the outlet of the air preheater is increased so as to ensure the necessary drying output of the pulverizing system.
8. Under the conditions of high-load operation of a unit, low-sulfur coal burning, low ammonia escape rate of an SCR denitration system and the like, the ash deposition tendency of a rotor is low, and the system can be switched to an energy-saving mode to operate: firstly, by arranging a connecting pipeline and an adjusting valve from an outlet of a cold end of a heating air bin to a dust remover, under the condition of slight dust deposition tendency of an air preheater, a negative pressure fan is not started, air leakage at the hot end of a rotor enters from the hot end of the heating air bin under the drive of pressure difference, flows towards the cold end direction, and enters an inlet flue of the dust remover through the connecting pipeline, so that the influence of the power consumption of the negative pressure fan on the energy consumption of a unit is reduced on the basis of ensuring the dust deposition prevention and contamination effect; and secondly, by arranging a connecting air duct of hot end and cold end air supply air ducts (secondary air ducts) and hot end and cold end connecting air ducts of the heating air bins, the circulating heating air bins can realize the circulation of partial boiler air supply (secondary air) and the countercurrent heat exchange of the secondary air and the flow direction of flue gas under the working condition that the air preheater has no dust deposition tendency, thereby reducing the temperature of the flue gas at the outlet of the air preheater and improving the recovery rate of the waste heat of the boiler and the unit efficiency.
9. When the unit burns fuel with high explosive index such as high volatile coal, the oxygen content of the medium at the inlet of the pulverizing system is lower than a certain threshold value, therefore, the system designs a connecting pipeline from the outlet flue of the induced draft fan to the inlet pipeline of the negative pressure fan and corresponding flow regulating devices such as a valve/a baffle plate, and a medium oxygen concentration measuring point is arranged on the pipeline from the outlet pipeline of the negative pressure fan to the primary air outlet of the air preheater and used as a basis for regulating the flow of the medium of low-temperature smoke at the outlet of the circulating induced draft fan.
10. In order to accurately control the hot end air leakage and extraction amount at the opening of the hot end fan-shaped plate, the actual flow rate of primary air and secondary air is prevented from being increased due to overlarge negative pressure suction force, the heat transfer effect of the air side is enhanced, the temperature level of a rotor is reduced, and the power consumption of a primary fan and a blower is increased; and the negative pressure is lower than the smoke pressure, smoke media are sucked into the heating air bin, the removal effect of contaminated products is influenced, and the problem of impeller corrosion of a negative pressure fan is caused.
The device and the system are mutually coupled and combined in a plurality of adjusting modes to form a solution of the comprehensive dust deposition and contamination prevention system of the rotary air preheater.
Drawings
FIG. 1 is a schematic structural diagram of the present invention;
FIG. 2 is a graph comparing the temperature distribution of the heat storage elements on the flue gas side of the air preheater.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.
Referring to fig. 1, a system for preventing rotary air preheater deposition from staining comprises a three-compartment rotary air preheater, the circulation cross section of which is divided into a secondary air compartment 1, a primary air compartment 3 and a flue gas compartment 4, the primary air compartment 3 and the flue gas compartment 4 are separated by a first partition plate 8, the secondary air compartment 1 and the flue gas compartment 4 are separated by a second partition plate 5, and the secondary air compartment 1 and the primary air compartment 3 are separated by a fourth partition plate 7. Flue gas generated by boiler combustion flows in from a flue gas inlet 19 of a flue gas sub-bin, primary air flows in from an air inlet duct 17 of a primary air sub-bin at a cold end, and secondary air flows in from an air inlet duct 15 of a secondary air sub-bin at the cold end; after heat exchange is carried out on each fluid in the air preheater, the flue gas flows out from the flue gas outlet flue 20 of the cold end flue gas branch bin, the primary air flows out from the primary air outlet air flue 18 of the hot end flue gas branch bin, and the secondary air flows out from the secondary air outlet air flue 16 of the hot end flue gas branch bin.
For the three-bin air preheater with the arrangement type, the independent heating air bin 2 is separated from the original secondary air bin by the third partition plate 6 in the rotor air side bin, the upper part of the independent heating air bin is connected with the heating air bin air inlet duct 11, and the lower part of the independent heating air bin is connected with the heating air bin air outlet duct 12. And a suction hole is formed in the top of the second partition plate 5 between the hot end secondary air sub-bin and the flue gas sub-bin and the top of the first partition plate 8 between the hot end primary air sub-bin and the flue gas sub-bin, the suction hole is communicated with the hot end radial air leakage gap of the air preheater so as to lead out hot end air leakage from the suction pipelines 9 and 10, third adjusting valves 37 and 38 are arranged on the air leakage suction pipeline on each side, and the air flow in the air leakage suction pipeline is adjusted through the third adjusting valves 37 and 38. The suction branch pipes on the two sides converge and then enter the heating air inlet duct 11 on the upper part of the heating air bin.
Specifically, the first partition plate 8, the second partition plate 5, the third partition plate 6 and the third partition plate 7 are all sector plates, and the air exhaust holes are uniformly distributed in rows along the radial direction of the sector plates.
Hot junction leaks out and gets into heating wind storehouse 2 by heating wind storehouse air inlet duct 11 on heating wind storehouse upper portion, form from the hot junction to the cold junction with flue gas forward flow, absorb heat from the hot junction component, heat release to moderate temperature section and cold junction component, than the scheme that flows from the cold junction to the hot junction, can realize the heating effect of the biggest region of middle temperature end bottom corrosion deposition risk by a wide margin, guarantee simultaneously that cold junction component temperature is higher than the acid dew point, and moderate temperature end bottom component temperature is higher than Ammonium Bisulfate (ABS) dew point temperature, thereby make ABS all deposit in the big passageway, enclosed plate type and surface plate enamel cold junction component layer, can carry out effective control to staining the product deposition rate through modes such as blowing the ash. The heating medium flows out from the heating air outlet duct 12 at the lower part of the heating air bin, passes through the dust removing device 51, removes fly ash particles carried in the medium, flows into the negative pressure fan 14 from the inlet end 13 of the negative pressure fan, and flows out from the outlet end 26 of the negative pressure fan after the pressure head is lifted. The inlet end and the outlet end of the negative pressure fan 14 are respectively provided with a fourth regulating valve 40 and a fifth regulating valve 41, and the change of the medium flow and the pressure head can be realized by regulating the opening degrees of the fourth regulating valve 40 and the fifth regulating valve 41.
Referring to fig. 1, in an embodiment, the outlet end of the negative pressure air blower 14 is connected to the secondary air outlet duct 16 and the primary air outlet duct 18 through a first connecting duct 28 and a second connecting duct 29, and a first adjusting valve 43 and a second adjusting valve 44 are respectively disposed on the first connecting duct 28 and the second connecting duct 29.
Specifically, the first connecting pipeline 28 and the second connecting pipeline 29 are communicated with the negative pressure fan 14 through a connecting main pipe with a first flow detecting device 46 and a duct heater 50, and a second flow detecting device 45 is arranged on the heating air outlet duct 12 near the heating air outlet end of the heating air bin. The communication manifold between the first flow detection device 46 and the duct heater 50 communicates with the heating air inlet duct 11 via a third communication duct 48 with a sixth control valve 47.
In the system, when the unit operates under a low load condition or the air preheater has a good sealing condition, the air leakage rate at the hot end of the air preheater is reduced, and when the medium flow rate at the outlet of the heating air bin 2, which is measured by the second flow rate detection device 45, is lower than the threshold flow rate under the condition, the sixth regulating valve 47 is opened to enable part of the hot air medium to flow back to the heating air bin, so that the medium flow rate in the air bin is not lower than the threshold flow rate under the condition.
Under the conditions that the unit combusts high-sulfur coal, the ammonia escape rate of an SCR denitration device is high and the like, the deposition temperature of ammonium bisulfate is increased, and the temperature increase amplitude of a bottom element at a middle temperature section is required to be increased; and during the low load period of the unit, when the difficult-to-catch fire inferior coal is burnt, the temperature requirement of the hot secondary air is higher so as to meet the stable combustion requirement of the boiler; when the powder process system grinds the fuel with low volatile component and high moisture, the temperature of the hot primary air is correspondingly increased to meet the drying requirement of the fuel. In summary, the air duct heater 50 is disposed in the communication main pipe, and various types such as electric heating, steam heating, or fuel oil and gas combustion heating can be adopted.
Referring to fig. 1, in one embodiment, the first communication duct 28 communicates with the blow-by extraction ducts 8, 10 through a fourth communication channel 33 with a seventh regulating valve 39.
To meet the explosion-proof safety requirement of a pulverizing system and reduce NO of fuel combustionxthe discharge concentration, the negative pressure air blower 14 exit end is connected to dust remover 22 and draught fan 24 through the fifth contact passageway 27 that is equipped with eighth adjusting valve 42, and the flue gas divides storehouse export flue 20 to be connected to dust remover 22, and dust remover 22 is connected to draught fan 24 through dust remover export flue 23, and the air-out pipeline 25 of draught fan 24 communicates with heating wind storehouse air outlet channel 12 through the sixth contact passageway 31 that is equipped with ninth adjusting valve 34. The heating air bin air outlet duct 12 is communicated with the fifth communicating duct 27 through a seventh communicating duct 32 provided with a tenth adjusting valve 36, and the secondary air bin air inlet duct 15 is communicated with the heating air bin air outlet duct 12 through an eighth communicating duct 30 provided with an eleventh adjusting valve 35.
The system is provided with a sixth connecting pipeline 31 from an outlet flue 25 of the induced draft fan to an air outlet duct 12 of the heating air bin and a corresponding ninth regulating valve 34; an oxygen concentration measurement point is provided on the second connecting line 29. When the milling system mills fuel with higher explosive index, or seeks to reduce NO by reducing the oxygen concentration of the drying medium of the milling systemxWhen the concentration is discharged, the eleventh regulating valve 35, the ninth regulating valve 34 and the third regulating valves 37 and 38 are regulated to control the temperature of the medium at the inlet of the negative pressure fan 14 and the oxygen concentration at proper levels, and then the medium enters the primary air branch bin air inlet duct 17 through the second connecting pipeline 29 and enters the pulverizing system to play the roles of drying and fuel conveying.
In this embodiment, under the circumstances such as the unit high load operation, the low sulfur coal of burning, SCR deNOx systems ammonia escape rate is lower, air heater deposition tendency is less, and this system can switch to energy-conserving mode operation: (1) a seventh connecting channel 32 from the air outlet channel 12 of the heating air bin to the fifth connecting channel 27 is arranged, a corresponding tenth adjusting valve 36 is arranged, the negative pressure fan 14 is not started, the fourth adjusting valve 40 and the fifth adjusting valve 41 are closed, air leakage at the hot end of the rotor enters from the hot end of the heating air bin 2 under the drive of pressure difference, flows towards the cold end direction and enters the inlet flue 21 of the dust remover through the seventh connecting channel 32, and on the basis of ensuring the dust deposition and contamination prevention effect, the influence of the power consumption of the negative pressure fan on the increase of the energy consumption of the unit is reduced; (2) under the working condition that the air preheater has no dust deposition tendency, the related pipeline valves of the hot-end air leakage suction and medium circulation system are closed, and the pipeline valves comprise third regulating valves 37 and 38 on a hot-end air leakage suction pipeline, a fourth regulating valve 40 and a fifth regulating valve 41 on two sides of a negative pressure fan, a first regulating valve 43, a second regulating valve 44, a tenth regulating valve 36 and the like, wherein an eleventh regulating valve 35 and a seventh regulating valve 39 are opened, so that part of boiler air (cold secondary air) enters a heating air bin through an eighth connecting channel 30, and enters a secondary air bin air outlet channel 16 through a fourth connecting channel 33 after being subjected to countercurrent heat exchange with smoke and absorbing heat, thereby improving the heat transfer efficiency of the air preheater, reducing the temperature of the smoke at the outlet of the air preheater, and improving the waste heat recovery utilization rate and the unit efficiency.
The outlet of the negative pressure fan is hot air, and different recycling ways can be selected according to the operation condition of the unit, the coal quality for combustion and the equipment investment, so that different system functions are realized: (1) the outlet hot air is introduced to the inlet flue 21 of the dust remover through the third connecting pipeline 27, and because the inlet flue of the dust remover is negative pressure, the full pressure rise and the power of the negative pressure fan are lower, but the air leakage of the air preheater flowing through the heating air bin 2 is not effectively recycled, so that the air leakage rate level of the air preheater cannot be effectively reduced; (2) the outlet hot air is introduced into the secondary air bin outlet air duct 16 of the air preheater through a first connecting pipeline 28 and is used as part of fuel combustion air; (3) the outlet hot air is introduced into the air outlet duct 18 of the primary air sub-bin of the air preheater through the second connecting pipeline 29 and is used as a medium for drying and conveying fuel of the pulverizing system. On the first connecting pipeline 28 and the second connecting pipeline 29, a first regulating valve 43 and a second regulating valve 44 are respectively arranged to regulate the flow ratio of the medium entering the primary air outlet duct 18 and the secondary air outlet duct 16. When the water content of the fuel entering the furnace is higher or the fuel belongs to the coal type difficult to catch fire, the temperature of the primary air entering the powder making system is higher, and at the moment, the second regulating valve 44 is closed or closed, so that more hot air media enter the secondary air sub-bin air outlet duct 16; the first connecting pipeline 28 and the second connecting pipeline 29 are communicated with an air outlet duct of the heating air bin through a connecting main pipe with a first flow detection device 46 and an air duct heater 50, a second flow detection device 45 is arranged on the air outlet duct of the heating air bin close to the air outlet end of the heating air bin, and the total flow of hot air media entering a primary air duct and a secondary air duct of an outlet of the air preheater can be obtained by the first flow detection device 46 so as to be convenient for monitoring and adjustment of operating personnel. At the moment, the hot end air leakage of the air preheater is sucked into the air channel by the negative pressure fan 14 to participate in fuel combustion, and on the premise that the excess air coefficient is not changed, the air flow passing through the primary air and the secondary air of the air preheater in the separate bins is reduced, the air/flue gas heat capacity ratio is reduced, and the temperature level of the rotor is further improved.
In order to accurately control the extraction amount of hot end air leakage, the actual air leakage flow of primary air and secondary air is prevented from increasing due to overlarge negative pressure suction force, the cooling of the air side is enhanced, the temperature level of a rotor is reduced, and the power consumption of a primary fan and an air feeder is increased; and the negative pressure is lower than the flue gas pressure, the flue gas medium is sucked into the rotor heating air bin, the removal effect of contamination products is influenced, and the impeller of the negative pressure fan is corroded, and the pressure difference measuring instrument 49 between the air leakage extraction pipeline and the flue gas sub-bin inlet flue is used for adjusting the pressure of the air leakage extraction pipelines 9 and 10 to be consistent with the pressure of the flue gas sub-bin inlet flue of the air preheater, so that the flow of primary air and secondary air cannot be increased, and the flue gas is prevented from being sucked into the rotor heating air bin.
A certain 600MW coal-fired power generating unit boiler is provided with 2 three-compartment rotary air preheaters with the models of LAP13494/2550, heat storage elements are arranged in three layers of a heat distribution end, a middle temperature section and a cold end, the heights of the heat storage elements are respectively 800mm, 800mm and 950mm, and under the original design scheme and the scheme of the patent, the temperature distribution of the heat storage elements on the smoke side of the air preheater is opposite to that shown in figure 2. It can be seen that, in the original design scheme, in the range of the height of the element at the bottom part of the medium-temperature section (as shown by the shaded area in the figure), ammonium bisulfate deposits and stains exist in the rotation period of the rotor, which may cause ash deposition and blockage; after adopting this patent scheme, middle temperature section and cold junction component temperature effectively promote to the upper limit (about 200 ℃) of the conventional deposit temperature interval of ammonium bisulfate is the benchmark, and middle temperature section component temperature all is higher than this temperature threshold value in whole revolution period, then the ammonium bisulfate deposit interval is all located the cold junction component within range, can effectively get rid of through modes such as blowing the ash to effectively prevent rotary air preheater heat accumulation component's deposition from staining.
The above examples are merely illustrative of the present invention clearly and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. Nor is it intended to be exhaustive of all embodiments. And obvious changes and modifications may be made without departing from the scope of the present invention.
Claims (10)
1. The utility model provides a prevent system that rotary air heater deposition stains, includes that inside is formed with the flue gas divides the air heater in storehouse, the branch storehouse of wind and overgrate air branch storehouse, the flue gas divides the storehouse and the wind divides and keeps apart through first baffle between the storehouse, the flue gas divides the storehouse and the overgrate air divides to keep apart through the second baffle between the storehouse, the overgrate air divides to separate out through the third baffle in the storehouse and adds the hot air storehouse, its characterized in that: the first partition plate and/or the second partition plate positioned at the hot end of the air preheater are/is provided with air extraction holes communicated with a radial air leakage gap at the hot end of the air preheater, the air extraction holes are communicated with an air inlet duct of the heating air bin through an air leakage extraction pipeline, and an air outlet duct of the heating air bin is connected to a negative pressure fan; the heating air bin is arranged at the hot end of the air preheater, and the heating air bin is arranged at the cold end of the air preheater.
2. The system of claim 1, wherein: the negative pressure fan is characterized in that the outlet end of the negative pressure fan is connected to a primary air sub-bin air outlet air duct and a secondary air sub-bin air outlet air duct through a first connecting pipeline and a second connecting pipeline respectively, a first adjusting valve and a second adjusting valve are arranged on the first connecting pipeline and the second connecting pipeline respectively, and a third adjusting valve is arranged on the air leakage pumping pipeline.
3. The system of claim 2, wherein: the first connecting pipeline and the second connecting pipeline are communicated with the negative pressure fan through a connecting main pipe with a first flow detection device and an air channel heater, and a second flow detection device is arranged on the air outlet channel of the heating air bin, close to the air outlet end of the heating air bin.
4. The system of claim 3, wherein: and a communication main pipe between the first flow detection device and the air channel heater is communicated with the air inlet channel of the heating air bin through a third communication channel with a sixth regulating valve.
5. The system of claim 4, wherein: and the second connecting pipeline is communicated with the air leakage pumping pipeline through a fourth connecting channel with a seventh regulating valve.
6. The system of claim 2, wherein: and the air outlet duct of the heating air bin is also provided with a dust removal device, and the inlet end and the outlet end of the negative pressure fan are respectively provided with a fourth regulating valve and a fifth regulating valve.
7. The system of claim 1, wherein: the system also comprises a pressure difference measuring instrument arranged between the air leakage extraction pipeline and the flue gas inlet flue of the smoke sub-bin.
8. The system of claim 1, wherein: the first partition plate, the second partition plate and the third partition plate are all sector plates, and the air pumping holes are uniformly distributed in rows along the radial direction of the sector plates.
9. The system according to any one of claims 1-8, wherein: the outlet end of the negative pressure fan is sequentially connected to the dust remover and the draught fan through a fifth connecting channel with an eighth adjusting valve, a smoke bin outlet flue is connected to the dust remover, an air outlet pipeline of the draught fan is communicated with an air outlet air channel of the heating air bin through a sixth connecting channel with a ninth adjusting valve, and an oxygen concentration measuring point is arranged on a second connecting pipeline.
10. The system of claim 9, wherein: and the secondary air sub-bin air inlet channel is communicated with the heating air bin air outlet channel through an eighth connecting channel with an eleventh adjusting valve.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110030573A (en) * | 2019-05-08 | 2019-07-19 | 国网湖南省电力有限公司 | A kind of system for preventing rotary regenerative air preheater dust stratification from staiing |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110030573A (en) * | 2019-05-08 | 2019-07-19 | 国网湖南省电力有限公司 | A kind of system for preventing rotary regenerative air preheater dust stratification from staiing |
| CN110030573B (en) * | 2019-05-08 | 2024-06-25 | 国网湖南省电力有限公司 | System for preventing dust accumulation and contamination of rotary air preheater |
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