Air leakage reducing and blocking preventing self-adaptive cooperative system for rotary air pre-heater and plate-type air pre-heater

Abstract

Compared with the prior art, the air leakage reducing and blocking preventing self-adaptive cooperative system for the rotary air pre-heater and the plate type air pre-heater has the advantages that the air leakage rate of the air pre-heater is reduced by heating primary air from a bypass of the rotary air pre-heater, and the air leakage rate of the air pre-heater is increased by replacing a heat storage element at the low-temperature section of the rotary air pre-heater into a large-channel plate type heat storage element. According to the rotary air pre-heater, the blocking phenomenon of the rotary air pre-heater is reduced, the secondary air preheating plate type air pre-heater is installed on the lower portion of the rotary air pre-heater, fresh air is further preheated, the cold end of the rotary air pre-heater is kept at the high temperature, NH4HSO4 bonding is avoided, the operation stability and economical efficiency of a power plant are improved, and huge indirect economic benefits can be generated; when the primary air heating plate-type air pre-heater and the secondary air preheating plate-type air pre-heater are arranged, an existing boiler operation layer platform is fully considered, the transformation workload and the length of a smoke and air duct are reduced to the maximum extent, local resistance and on-way resistance of the smoke and air duct are reduced, and the purpose of the utility model is achieved.

Description

Technical Field

[0001] The utility model relates to an air preheater for a power plant boiler, in particular to an adaptive coordinated system for reducing air leakage and preventing blockage of a rotary air preheater and a plate air preheater. Background Art

[0002] An air preheater is a heat exchange device that uses the waste heat from boiler exhaust to heat the air required for combustion. Rotary air preheaters have the advantages of high heat transfer surface density, small size, flexible layout, and high heat transfer efficiency using countercurrent heat exchange. They are widely used in large generator sets above 600MW.

[0003] However, after long-term operation, the rotary air preheater has also exposed many problems. The rotary air preheater is arranged after the denitrification and before the dust collector. In addition to containing a large amount of dust in the flue gas, the SO2 produced by fuel combustion is converted into SO3 in large quantities under the action of the catalyst when passing through the denitrification device. It reacts with the ammonia that escapes during the denitrification process to form NH4HSO4. NH4HSO4 begins to turn into liquid at temperatures below 200°C and has high viscosity. After it adheres to the surface of the rotary air preheater heat storage element, it combines with the fly ash in the flue gas to cause flow channel blockage. The three-compartment rotary air preheater adopts a heat storage and heat exchange heat transfer method. The rotor rotates counterclockwise under the drive of the motor, passing through the flue gas, secondary air, and primary air areas in turn. The heat storage element absorbs heat in the flue gas flow area and releases heat in the primary and secondary air flow areas to achieve heat transfer. The rotation of the rotor will cause air leakage, and the pressure difference between the primary air, secondary air and flue gas will cause direct air leakage, especially when the primary air pressure is high and the leakage rate is large. When the rotary air preheater has been running for a long time, the leakage rate may even exceed 20%.

[0004] With the rapid development of photovoltaic and wind power, deep peak regulation has become the norm for thermal power units. During deep peak regulation, boiler load is maintained between 15% and 20% of the design load, resulting in lower exhaust gas temperatures and uneven flow distribution on the boiler's rear heating surface. This exacerbates air preheater blockage and air leakage. Blockage increases the air preheater pressure differential and insufficient fan output. Air leakage reduces the air preheater's heat transfer efficiency, increases ineffective heat transfer, lowers flue gas temperatures, and exacerbates NH4HSO4 precipitation. Blockage and air leakage seriously affect boiler thermal efficiency and safe unit operation.

[0005] Therefore, there is a particular need for an adaptive collaborative system for reducing air leakage and preventing blockage of a rotary air preheater and a plate air preheater to solve the above-mentioned existing problems. Utility Model Content

[0006] The purpose of the utility model is to provide a rotary air preheater and plate air preheater leakage reduction and anti-clogging adaptive collaborative system, in view of the deficiencies of the existing technology, overcome the shortcomings of the existing three-compartment rotary air preheater with high leakage rate and serious clogging, and will not cause NH4HSO4 adhesion, thereby improving the stability and economy of power plant operation.

[0007] The technical problem solved by the present invention can be achieved by adopting the following technical solutions:

[0008] A self-adaptive coordinated system for reducing air leakage and preventing blockage of rotary air preheater and plate air preheater comprises a rotary air preheater, a primary air heating plate air preheater and a secondary air preheating plate air preheater; the rotary air preheater and the secondary air preheating plate air preheater are arranged in series, and the rotary air preheater and the primary air heating plate air preheater are arranged in parallel; the primary air heating plate air preheater and the secondary air preheating plate air preheater are both provided with a heat recovery bypass and a high-temperature desalination bypass; the high-temperature flue gas enters the flue gas bin of the rotary air preheater from the main inlet flue, releases heat to the heat storage element and then enters the secondary air preheater. The secondary air preheats the plate air preheater, and the secondary air flows out from the main outlet flue after heat exchange. The secondary air enters the secondary air preheating plate air preheater through the inlet secondary air duct, and enters the secondary air bin of the rotary air preheater after preheating, and is discharged from the outlet secondary air duct after absorbing heat from the heat storage element. The primary air enters the primary air heating plate air preheater through the inlet primary air duct, and is discharged through the outlet primary air duct after heat exchange with the bypass flue gas. The bypass flue gas flows from top to bottom through the bypass inlet flue through the primary air heating plate air preheater, and enters the main outlet flue through the bypass outlet flue after heat exchange with the primary air.

[0009] In a preferred embodiment of the present invention, the rotary air preheater includes a flue gas bin and a secondary air bin, and the low-temperature section heat storage element of the rotary air preheater is a large channel plate type.

[0010] In a preferred embodiment of the present invention, the secondary air preheating plate air preheater is arranged with a heat recovery bypass and a high-temperature desalination bypass. By opening the heat recovery bypass, part of the heated secondary air is extracted and led to the blower, so that the temperature of the secondary air fresh air is raised to above 20°C, thereby avoiding the precipitation of NH4HSO4 on the secondary air preheating plate air preheater; if NH4HSO4 is precipitated on the secondary air preheating plate air preheater, by opening the high-temperature desalination bypass, part of the heated secondary air is extracted and introduced into the secondary air preheating plate air preheater inlet flue, and the precipitated NH4HSO4 is heated so that it is gasified and carried away by the flue gas.

[0011] In a preferred embodiment of the present invention, the primary air heating plate air preheater extracts part of the flue gas to heat the primary air, the bypass flue gas passes through the primary air heating plate air preheater from top to bottom, and the primary air passes through the primary air heating plate air preheater from left to right through the bypass primary air duct; the bypass flue gas returns to the main outlet flue through the bypass outlet flue, and the heated primary air returns to the main outlet primary air duct through the bypass outlet primary air duct.

[0012] In a preferred embodiment of the present invention, the primary air heating plate air preheater is arranged with a heat recovery bypass and a high-temperature desalination bypass. By opening the heat recovery bypass, part of the heated primary air is extracted and led to the primary fan, so that the temperature of the primary air is raised to above 20°C, thereby avoiding the precipitation of NH4HSO4 on the primary air heating plate air preheater; if NH4HSO4 is precipitated on the primary air heating plate air preheater, by opening the high-temperature desalination bypass, part of the heated primary air is extracted and introduced into the inlet flue of the primary air heating plate air preheater, and the precipitated NH4HSO4 is heated so that it is vaporized and carried away by the flue gas.

[0013] In a preferred embodiment of the present invention, the bypass air duct and flue of the primary air heating plate air preheater and the secondary air preheating plate air preheater are both provided with valves for adjusting the bypass air volume and the primary air temperature.

[0014] In a preferred embodiment of the present invention, the primary air heating plate air preheater and the secondary air preheating plate air preheater use fully welded corrugated plates as heat exchange plates; the flue gas side flow channel of the corrugated plate is a straight channel, and the air side channel of the corrugated plate is a periodic corrugated channel.

[0015] In a preferred embodiment of the present invention, the rotary low-temperature section large-channel heat storage element is constructed by stacking two straight corrugated plates.

[0016] The utility model discloses a self-adaptive coordinated system for reducing air leakage and preventing blockage of a rotary air preheater and a plate air preheater. Compared with the prior art, the air leakage rate of the air preheater is reduced by bypassing the primary air from the rotary air preheater for heating. The blockage of the rotary air preheater is reduced by replacing the heat storage element of the low-temperature section of the rotary air preheater with a large-channel plate type. The fresh air is further preheated by installing a secondary air preheating plate air preheater at the bottom of the rotary air preheater, so that the cold end of the rotary air preheater is kept at a high temperature, NH4HSO4 adhesion will not occur, the stability and economy of the power plant operation are improved, and huge indirect economic benefits can be generated. When arranging the primary air heating plate air preheater and the secondary air preheating plate air preheater, full consideration is given to utilizing the existing boiler operating layer platform, so as to minimize the workload of transformation and the length of the smoke and air duct, reduce the local resistance and the resistance along the smoke and air duct, and achieve the purpose of the utility model.

[0017] The features of the present invention can be clearly understood by referring to the drawings and the following detailed description of preferred embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a flow chart of the adaptive collaborative system for reducing air leakage and preventing blockage of a rotary air preheater and a plate air preheater according to the present invention;

[0019] Figure 2 This is a schematic structural diagram of a plate-type air preheater of the present utility model;

[0020] Figure 3 This is a schematic structural diagram of the large-channel heat storage element of the present invention.

[0021] Explanation of the accompanying figures: 1-rotary air preheater, 2-primary air heating plate air preheater, 3-secondary air preheating plate air preheater, 4A-main inlet flue, 4B-main outlet flue, 5A-bypass inlet flue, 5B-bypass outlet flue, 6A-inlet primary air duct, 6B-outlet primary air duct, 6C-heat recovery primary air duct, 6D-high-temperature desalination primary air duct, 6E-heat recovery primary air duct valve, 6F-high-temperature desalination primary air duct valve, 7A-inlet secondary air duct, 7B-outlet secondary air duct, 7C-heat recovery secondary air duct, 7D-high-temperature desalination secondary air duct, 7E-heat recovery secondary air duct valve, 7F-high-temperature desalination secondary air duct valve. DETAILED DESCRIPTION

[0022] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below with reference to specific illustrations.

[0023] Example

[0024] like Figures 1 to 3 As shown, the utility model is a rotary air preheater and plate air preheater leakage reduction and anti-clogging adaptive collaborative system, comprising a rotary air preheater 1, a primary air heating plate air preheater 2 and a secondary air preheating plate air preheater 3; the rotary air preheater 1 and the secondary air preheating plate air preheater 3 are arranged in series, and the rotary air preheater 1 and the primary air heating plate air preheater 2 are arranged in parallel, and the primary air heating plate air preheater 2 and the secondary air preheating plate air preheater 3 are both arranged with a heat recovery bypass and a high-temperature desalination bypass.

[0025] The rotary air preheater 1 is an existing heat exchange equipment and pipeline. The original rotary air preheater includes a flue gas bin, a primary air bin and a secondary air bin. The primary air is taken out of the rotary air preheater, and the original primary air bin is also changed to a secondary air bin to increase the circulation area of the secondary air. At the same time, the low-temperature section heat storage element of the rotary air preheater 1 is changed to a large channel plate type to reduce the possibility of dust accumulation in the heat storage element. A secondary air preheating plate air preheater 3 is installed at the lower part of the rotary air preheater 1 to further increase the temperature of the cold end of the rotary air preheater 1 and reduce the possibility of NH4HSO4 precipitation in the low-temperature section of the rotary air preheater.

[0026] The secondary air preheating plate air preheater 3 is arranged with a heat recovery bypass and a high-temperature desalination bypass. Under winter operating conditions, the secondary air fresh air drops below -20°C. By opening the heat recovery bypass, part of the heated secondary air is extracted and led to the front of the blower, so that the temperature of the secondary air fresh air is raised to above 20°C, thereby preventing NH4HSO4 from precipitating on the secondary air preheating plate air preheater 3; if NH4HSO4 is precipitated on the secondary air preheating plate air preheater 3, by opening the high-temperature desalination bypass, part of the heated secondary air is extracted and introduced into the inlet flue of the secondary air preheating plate air preheater 3, and the precipitated NH4HSO4 is heated so that it is vaporized and carried away by the flue gas.

[0027] The primary air heating plate air preheater 2 extracts part of the flue gas to heat the primary air. The bypass flue gas passes through the primary air heating plate air preheater 2 from top to bottom, and the primary air passes through the primary air heating plate air preheater 2 from left to right through the bypass primary air duct; the bypass flue gas returns to the main outlet flue duct 4B through the bypass outlet flue 5B, and the heated primary air returns to the main outlet primary air duct through the bypass outlet primary air duct.

[0028] The primary air heating plate air preheater 2 is arranged with a heat recovery bypass and a high-temperature desalination bypass. Under winter operating conditions, the fresh primary air drops below -20°C. By opening the heat recovery bypass, part of the heated primary air is extracted and led to the front of the primary fan, so that the temperature of the fresh primary air is raised to above 20°C, avoiding the precipitation of NH4HSO4 on the primary air heating plate air preheater 2; if NH4HSO4 is precipitated on the primary air heating plate air preheater 2, by opening the high-temperature desalination bypass, part of the heated primary air is extracted and introduced into the inlet flue of the primary air heating plate air preheater 2, and the precipitated NH4HSO4 is heated so that it is vaporized and carried away by the flue gas.

[0029] The specific working process of the adaptive collaborative system for reducing air leakage and preventing blockage of rotary air preheater and plate air preheater of the utility model is as follows:

[0030] refer to Figure 1The high-temperature flue gas enters the flue gas bin of the rotary air preheater 1 from the main inlet flue 4A, releases heat to the heat storage element, and then enters the secondary air preheating plate air preheater 3. After exchanging heat with the secondary air, it flows out from the main outlet flue 4B. The original primary air bin of the rotary air preheater is also changed into a secondary air bin. The secondary air enters the secondary air preheating plate air preheater 3 through the inlet secondary air duct 7A, and after preheating, it enters the secondary air bin of the rotary air preheater 1, absorbs heat from the heat storage element, and is discharged from the outlet secondary air duct 7B. The primary air enters the primary air heating plate air preheater 2 through the inlet primary air duct 6A, and is discharged through the outlet primary air duct 6B after heat exchange with the bypass flue gas. The bypass flue gas flows from top to bottom through the bypass inlet flue 5A through the primary air heating plate air preheater 2, and enters the main outlet flue 4B through the bypass outlet flue 5B after heat exchange with the primary air.

[0031] Under winter operating conditions, the fresh air of the primary air drops below -20°C. By opening the heat recovery primary air duct valve 6E, part of the heated primary air is extracted and led to the primary fan through the heat recovery primary air duct 6C, so that the temperature of the fresh air of the primary air is raised to above 20°C, avoiding the precipitation of NH4HSO4 on the primary air heating plate air preheater 2; if NH4HSO4 is really precipitated on the primary air heating plate air preheater 2, by opening the high-temperature desalination primary air duct valve 6F, part of the heated primary air is extracted and introduced into the flue gas side of the primary air heating plate air preheater 2 through the high-temperature desalination primary air duct 6D, and the precipitated NH4HSO4 is heated so that it is vaporized and carried away by the flue gas.

[0032] Under winter operating conditions, the temperature of the secondary air and fresh air drops below -20°C. By opening the reheating secondary air duct valve 7E, part of the heated secondary air is extracted and led to the front of the blower through the reheating secondary air duct 7C, so that the temperature of the secondary air and fresh air is raised to above 20°C, thereby preventing NH4HSO4 from precipitating on the secondary air preheating plate air preheater 3; if NH4HSO4 is really precipitated on the secondary air preheating plate air preheater 3, by opening the high-temperature desalination secondary air duct valve 7F, part of the heated secondary air is extracted and introduced into the flue gas side of the secondary air preheating plate air preheater 3 through the high-temperature desalination secondary air duct 7D, and the precipitated NH4HSO4 is heated so that it is vaporized and carried away by the flue gas.

[0033] The utility model's adaptive collaborative system for reducing air leakage and preventing blockage of rotary air preheaters and plate air preheaters has the following beneficial effects:

[0034] The primary air is bypassed from the rotary air preheater and enters the primary air heating plate air preheater for heating. The primary air heating plate air preheater adopts a fully welded sealing method to achieve zero primary air leakage rate. At the same time, the secondary air pressure of the rotary air preheater is relatively low, and the air leakage rate is also greatly reduced. The original primary air silo of the rotary air preheater is also changed to a secondary air silo, increasing the flow area of the secondary air and reducing the flow resistance. At the same time, the low-temperature section heat storage element of the rotary air preheater is changed to a large channel plate type, reducing the possibility of dust accumulation on the heat storage element. A secondary air preheating plate air preheater is installed at the bottom of the rotary air preheater to further increase the temperature of the cold end of the rotary air preheater and reduce the possibility of NH4HSO4 precipitation in the low-temperature section of the rotary air preheater. The primary air heating plate air preheater and the secondary air preheating plate air preheater use special straight corrugated channels that are less prone to clogging. The presence of a heat recovery bypass allows them to operate normally even in winter conditions. If NH4HSO4 precipitation and adhesion do occur in the plate air preheater, it can be removed through the high-temperature desalination bypass. The rotary air preheater has a lower air leakage rate, which reduces the drop in flue gas temperature caused by air leakage and mixing, reduces NH4HSO4 precipitation, reduces clogging, and reduces equipment costs and maintenance personnel costs caused by air preheater maintenance. This improves the stability of power plant operations and can generate huge indirect economic benefits. When arranging the primary air heating plate air preheater and the secondary air preheating plate air preheater, full consideration is given to utilizing the existing boiler operating floor platform to minimize the renovation workload and the length of the smoke and air duct, and reduce the local resistance and along-the-flow resistance of the smoke and air duct.

[0035] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for illustrative purposes. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and improvements shall fall within the scope of the present invention as claimed, and the scope of protection claimed by the present invention shall be defined by the appended claims and their equivalents.

Claims

1. An adaptive collaborative system for reducing air leakage and preventing blockage of rotary air preheater and plate air preheater, characterized in that: It includes rotary air preheater, primary air heating plate air preheater and secondary air preheating plate air preheater; the rotary air preheater and secondary air preheating plate air preheater are arranged in series, and the rotary air preheater and primary air heating plate air preheater are arranged in parallel. Both the primary air heating plate air preheater and the secondary air preheating plate air preheater are provided with heat recovery bypass and high temperature desalination bypass; the high temperature flue gas enters the flue gas bin of the rotary air preheater from the main inlet flue, releases heat to the heat storage element and then enters the secondary air preheating plate air preheater, and the secondary air exchange After being heated, it flows out from the main outlet flue, and the secondary air enters the secondary air preheating plate air preheater through the inlet secondary air duct. After preheating, it enters the secondary air bin of the rotary air preheater, and is discharged from the outlet secondary air duct after absorbing heat from the heat storage element. The primary air enters the primary air heating plate air preheater through the inlet primary air duct, and is discharged through the outlet primary air duct after heat exchange with the bypass flue gas. The bypass flue gas flows from top to bottom through the bypass inlet flue through the primary air heating plate air preheater, and enters the main outlet flue through the bypass outlet flue after heat exchange with the primary air.

2. The adaptive coordinated system for reducing air leakage and preventing blockage of a rotary air preheater and a plate air preheater according to claim 1 is characterized in that: The rotary air preheater includes a flue gas bin and a secondary air bin, and the low-temperature section heat storage element of the rotary air preheater is a large channel plate type.

3. The adaptive coordinated system for reducing air leakage and preventing blockage of a rotary air preheater and a plate air preheater according to claim 1 is characterized in that: The primary air heating plate air preheater extracts part of the flue gas to heat the primary air, the bypass flue gas passes through the primary air heating plate air preheater from top to bottom, and the primary air passes through the primary air heating plate air preheater from left to right through the bypass primary air duct; the bypass flue gas returns to the main outlet flue through the bypass outlet flue, and the heated primary air returns to the main outlet primary air duct through the bypass outlet primary air duct.

4. The adaptive coordinated system for reducing air leakage and preventing blockage of a rotary air preheater and a plate air preheater according to claim 1 is characterized in that: The bypass air duct and flue of the primary air heating plate type air preheater and the secondary air preheating plate type air preheater are both provided with valves for adjusting the bypass air volume and the primary air temperature.

5. The adaptive coordinated system for reducing air leakage and preventing blockage of a rotary air preheater and a plate air preheater according to claim 1 is characterized in that: The primary air heating plate type air preheater and the secondary air preheating plate type air preheater use fully welded corrugated plates as heat exchange plates; the flue gas side flow channel of the fully welded corrugated plates is a straight channel, and the air side channel of the fully welded corrugated plates is a periodic corrugated channel.

6. The adaptive coordinated system for reducing air leakage and preventing blockage of a rotary air preheater and a plate air preheater according to claim 1 is characterized in that: The large channel heat storage element of the low temperature section of the rotary air preheater is constructed by stacking two straight corrugated plates.

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