Anti-corrosion, anti-ash-blocking and anti-abrasion air pre-heater device

Abstract

The utility model relates to the field of air pre-heaters, in particular to an anti-corrosion, anti-ash-blocking and anti-abrasion air pre-heater device which comprises a box body, and the box body comprises a smoke inlet, a smoke outlet, an air inlet, an air outlet, a front tube plate, a middle tube plate, a rear tube plate and a plurality of air pre-heater tubes. The air pre-heater tube comprises a protection tube and a composite heat exchange tube; the protection pipe is arranged in the top area of the air pre-heater pipe; the composite heat exchange tube is arranged at the lower part of the protection tube; the composite heat exchange pipe comprises a cold end pipe section located in the front end area of the box body and a main body pipe section located at the rear end of the cold end pipe section, the main body pipe section comprises a second inner steel pipe and a second enamel layer arranged on the outer surface of the second inner steel pipe, and the cold end pipe section comprises a third inner steel pipe and an outer steel pipe arranged on the outer surface of the third inner steel pipe; a heat conduction layer is arranged between the inner steel pipe and the outer steel pipe. The tubular air preheater can effectively solve the problem that in the prior art, a tubular air preheater is prone to corrosion and ash blocking, and the heat exchange capacity of the air preheater is guaranteed.

Description

Technical Field

[0001] The utility model relates to the field of air preheaters, in particular to an air preheater device which is corrosion-resistant, dust-blocking-resistant and wear-resistant. Background Art

[0002] Air preheater is also called air preheater for short. It is a preheating device to improve the heat exchange performance of boiler and reduce heat loss. The function of air preheater is to use the heat of flue gas at the tail of boiler to heat the air required for fuel combustion to improve the thermal efficiency of boiler. Its working principle is: flue gas is heated by the heating surface to reduce the flue gas temperature.

[0003] In small units, tubular air preheaters are most commonly used. However, the enamel of the existing air preheater is easily damaged or has porosity problems during manufacturing, installation and maintenance, so that the carbon steel pipe of the air preheater at the damaged part is exposed in the flue gas. When the metal wall temperature is lower than the dew point of sulfuric acid vapor, sulfuric acid condenses on the metal surface of the heating surface and corrodes the metal of the heating surface. In addition, due to the high flue gas flow rate at the air preheater, a large amount of fly ash erodes and wears the enamel. The enamel of the parts that are frequently eroded or rubbed by fly ash for a long time is damaged and low-temperature corrosion occurs. In the denitrification process, ammonia reacts with nitrogen oxides in the flue gas and then reacts with sulfur trioxide in the flue gas to generate ammonium bisulfate. Ammonium bisulfate has a large viscosity and will be deposited in the middle temperature section or cold end of the air preheater, adsorbing particulate matter in the flue gas, causing a large amount of ash to adhere to the metal surface and interlayer of the heat exchanger, making the flue gas channel unsmooth or even blocking the tube bundle. Since the ash accumulation acts as an insulation between the flue gas and the tube wall, the wall temperature is reduced, and low-temperature dew point corrosion is easily formed under the ash accumulation.

[0004] Therefore, after long-term operation, the existing air preheater will have serious dust accumulation and even dust blockage. At the same time, the air leakage problem is also very serious, resulting in a serious lack of heat exchange capacity of the air preheater. Utility Model Content

[0005] Therefore, in view of the above problems, the utility model proposes an anti-corrosion, anti-dust blocking and anti-wear air preheater device to solve the problem that the tubular air preheater in the prior art is prone to corrosion and dust blocking.

[0006] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0007] An anti-corrosion, anti-dust and anti-wear air preheater device comprises a box body, characterized in that the box body comprises a flue gas inlet, a flue gas outlet, an air inlet, an air outlet, a front tube sheet, an intermediate tube sheet, a rear tube sheet and a plurality of air preheater tubes horizontally arranged in the front tube sheet, the intermediate tube sheet and the rear tube sheet; the air preheater tubes comprise a protective tube and a composite heat exchange tube.

[0008] The protection tubes are evenly arranged side by side in the top area of ​​the air preheater tube; the protection tubes include a first inner steel tube and a first enamel layer arranged on the surface of the first inner steel tube, the front and rear ends of the protection tubes are closed structures, and the front and rear ends of the protection tubes are respectively welded to the front tube sheet and the rear tube sheet.

[0009] The composite heat exchange tubes are distributed in a matrix at the lower part of the protective tube; the composite heat exchange tubes include a cold end tube section located in the front end area of ​​the box body and a main tube section located at the rear end of the cold end tube section, the main tube section includes a second inner steel tube and a second enamel layer arranged on the outer surface of the second inner steel tube, the cold end tube section includes a third inner steel tube and an outer steel tube arranged on the outer surface of the third inner steel tube, and a heat conductive layer is arranged between the inner steel tube and the outer steel tube; the second inner steel tube and the third inner steel tube are connected as one piece.

[0010] The front end of the composite heat exchange tube is slidably connected to the front tube sheet, and the rear end of the composite heat exchange tube is welded to the rear tube sheet.

[0011] Furthermore, the number of the intermediate tube sheets is 2.

[0012] Furthermore, the wall thickness of the first inner steel tube is greater than the wall thickness of the second inner steel tube.

[0013] Furthermore, the thickness of the first enamel layer and the second enamel layer is 0.4 mm-0.5 mm.

[0014] Furthermore, the material of the first inner steel pipe, the second inner steel pipe and the third inner steel pipe is ND steel, and the material of the outer steel pipe is 2205 stainless steel.

[0015] Furthermore, the length of the cold end pipe section is 600 mm.

[0016] Furthermore, the composite heat exchange tube and the front tube plate are sealed and connected by a graphite gasket.

[0017] Furthermore, a temperature-resistant gasket is provided between the air preheater tube and the intermediate tube plate, and the temperature-resistant gasket is a fluororubber gasket.

[0018] Furthermore, a monitoring mechanism is included, which includes a first temperature sensor, a second temperature sensor, a third temperature sensor, a PLC controller and an audible and visual alarm; the first temperature sensor is arranged at the smoke inlet; the second temperature sensor is arranged at the smoke outlet, and the third temperature sensor is arranged at the air outlet; the first temperature sensor, the second temperature sensor, the third temperature sensor and the audible and visual alarm are all electrically connected to the PLC controller.

[0019] By adopting the above technical solution, the beneficial effects of the utility model are:

[0020] 1. By arranging an enamel layer on the outer surface of the main pipe section of the composite heat exchange tube, the enamel layer has a small friction coefficient and a smooth surface, and is not easy to adhere to dust and other substances, which can ensure the anti-dust accumulation performance of the equipment; by arranging an outer steel pipe outside the third inner steel pipe of the cold end pipe section, the heat transfer resistance can be increased, the heat transfer of the cold end pipe section can be reduced, and the dust accumulation corrosion of the cold end pipe section due to low temperature can be effectively avoided; the outer steel pipe is made of 2205 stainless steel. Both 2205 stainless steel and enamel do not react with acids and alkalis, and are not easy to corrode, which effectively improves the anti-corrosion performance of the equipment, ensures the long-term safe and stable operation of the equipment, and indirectly produces energy-saving effects and improves economic benefits.

[0021] 2. By setting a row of protective tubes above the composite heat exchange tubes, due to the high flue gas flow rate of the air preheater, the topmost air preheater tube will be directly eroded by the flue gas. The setting of the protective tubes can effectively prevent the air preheater tubes from low-temperature corrosion due to fly ash erosion and wear, thereby ensuring the service life of the air preheater.

[0022] 3. By installing a temperature-resistant gasket between the air preheater tube and the intermediate tube sheet, the enamel layer can be effectively prevented from being damaged by high temperature during welding, and the weld can be prevented from being corroded and broken; at the same time, the air preheater tube and the intermediate tube sheet can be prevented from being damaged by collision, and a certain expansion space for the air preheater tube can be guaranteed to prevent the enamel from being damaged due to large thermal deviation.

[0023] 4. By setting a graphite gasket between the composite heat exchange tube and the front tube sheet, a good sealing effect can be achieved, effectively preventing air leakage, ensuring the heat exchange efficiency of the air preheater, and saving energy.

[0024] 5. By setting up a monitoring mechanism, the temperatures of the inlet flue gas, outlet flue gas and outlet air are monitored in real time, and the temperature difference between the actual temperature value and the design temperature value of the inlet flue gas, outlet flue gas and outlet air is calculated by the PLC controller. If the temperature difference among the three is not much, it means that the equipment is operating normally. If the temperature difference among the three exceeds the set threshold range, it indicates that the equipment may have problems such as dust blockage, corrosion, and wear. At this time, the PLC controller controls the sound and light alarm to send an alarm signal to remind the staff to inspect the equipment to avoid large losses. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a main structural schematic diagram of the utility model;

[0026] Figure 2 It is a right view structural schematic diagram of the utility model;

[0027] Figure 3 It is a schematic diagram of the structure of the protection tube;

[0028] Figure 4 It is a structural schematic diagram of a composite heat exchange tube;

[0029] Figure 5 It is a circuit connection diagram of the monitoring organization. DETAILED DESCRIPTION

[0030] The utility model is now further described in conjunction with the accompanying drawings and specific implementation methods.

[0031] refer to Figures 1 to 5 This embodiment provides an anti-corrosion, anti-blocking, anti-ash and anti-wear air preheater device, comprising a box body 1, characterized in that the box body 1 comprises a flue gas inlet 11, a flue gas outlet 12, an air inlet 13, an air outlet 14, a front tube sheet 2, an intermediate tube sheet 3, a rear tube sheet 4 and a plurality of air preheater tubes horizontally arranged in the front tube sheet 2, the intermediate tube sheet 3 and the rear tube sheet 4; the air preheater tube comprises a protective tube 5 and a composite heat exchange tube 6. Flue gas enters from the flue gas inlet 11 at the top of the box body 1 and is discharged from the flue gas outlet 12 at the bottom of the box body 1, and air enters from the air inlet 13 on the front side of the box body 1 and is discharged from the air outlet 14 on the rear side of the box body 1, thereby heating the air.

[0032] The protection tubes 5 are evenly arranged side by side in the top area of ​​the air preheater tubes; the protection tubes 5 include a first inner steel tube 51 and a first enamel layer 52 arranged on the surface of the first inner steel tube 51. The front and rear ends of the protection tubes 5 are closed structures, and the front and rear ends of the protection tubes 5 are respectively welded to the front tube sheet 2 and the rear tube sheet 4. Since the flue gas flow rate of the air preheater is relatively high, the topmost air preheater tube will be directly scoured by the flue gas. The provision of the protection tubes 5 can effectively prevent the air preheater tubes from low-temperature corrosion due to fly ash scouring and wear, thereby ensuring the service life of the air preheater.

[0033] The composite heat exchange tubes 6 are distributed in a matrix at the lower part of the protection tube 5; the composite heat exchange tubes 6 include a cold end tube section located in the front end area of ​​the box body 1 and a main tube section located at the rear end of the cold end tube section, the main tube section includes a second inner steel tube 61 and a second enamel layer 62 arranged on the outer surface of the second inner steel tube 61, the cold end tube section includes a third inner steel tube 63 and an outer steel tube 64 arranged on the outer surface of the third inner steel tube 63, and a heat conductive layer 65 is arranged between the inner steel tube and the outer steel tube 64; the second inner steel tube 61 and the third inner steel tube 63 are connected as a whole. The enamel layer has a small friction coefficient and a smooth surface, and is not easy to adhere to dust and other substances, which can ensure the anti-dust accumulation performance of the equipment; by arranging an outer steel pipe 64 at the cold end pipe section, the heat transfer thermal resistance can be increased, the heat transfer of the cold end pipe section can be reduced, and the dust accumulation and corrosion of the cold end pipe section due to low temperature can be effectively avoided; the outer steel pipe 64 and enamel do not react with acids and alkalis, and are not easy to corrode, which effectively improves the anti-corrosion performance of the equipment, ensures the long-term safe and stable operation of the equipment, indirectly produces energy-saving effects, and improves economic benefits.

[0034] The front end of the composite heat exchange tube 6 is slidably connected to the front tube sheet 2, and the rear end of the composite heat exchange tube 6 is welded to the rear tube sheet 4; the composite heat exchange tube 6 is sealed and connected to the front tube sheet 2 by a graphite gasket (not shown in the figure). The graphite gasket can achieve a good sealing effect, effectively prevent air leakage, and ensure the heat exchange efficiency of the air preheater.

[0035] A heat-resistant gasket (not shown in the figure) is arranged between the air preheater tube and the intermediate tube sheet 3. The heat-resistant gasket is a fluororubber gasket. The heat-resistant gasket can effectively prevent the high temperature during welding from damaging the enamel layer, and avoid corrosion and fracture of the weld; at the same time, it can prevent the air preheater tube from colliding with the intermediate tube sheet 3 and ensure a certain expansion space for the air preheater tube, and prevent the enamel from being damaged due to large thermal deviation of the tube.

[0036] In this specific embodiment, the number of the intermediate tube sheets 3 is 2. The provision of the intermediate tube sheets 3 is beneficial to enhancing the overall structural strength of the box body 1.

[0037] In this specific embodiment, the wall thickness of the first inner steel tube 51 is greater than the wall thickness of the second inner steel tube 61. The wall thickness of the first inner steel tube 51 is limited in order to ensure the strength of the protection tube 5 and achieve a more stable protection effect.

[0038] In this specific embodiment, the thickness of the first enamel layer 52 and the second enamel layer 62 is 0.4 mm-0.5 mm.

[0039] In this specific embodiment, the material of the first inner steel tube 51, the second inner steel tube 61 and the third inner steel tube 63 is ND steel, and the material of the outer steel tube 64 is 2205 stainless steel.

[0040] In this specific embodiment, the length of the cold end pipe section is 600 mm.

[0041] In this specific embodiment, a monitoring mechanism is also included, which includes a first temperature sensor 71, a second temperature sensor 72, a third temperature sensor 73, a PLC controller 74 and an audible and visual alarm 75; the first temperature sensor 71 is arranged at the smoke inlet 11; the second temperature sensor 72 is arranged at the smoke outlet 12, and the third temperature sensor 73 is arranged at the air outlet 14; the first temperature sensor 71, the second temperature sensor 72, the third temperature sensor 73, and the audible and visual alarm are all electrically connected to the PLC controller 74. Under normal circumstances, when the temperature of the inlet flue gas of the same air preheater increases, the temperature of the outlet air and the temperature of the outlet flue gas should also increase accordingly, and the temperature difference remains basically unchanged. The monitoring mechanism measures the temperature of the inlet flue gas, outlet flue gas and outlet air in real time through the first temperature sensor 71, the second temperature sensor 72 and the third temperature sensor 73, and calculates the temperature difference between the actual temperature value and the design temperature value of the inlet flue gas, outlet flue gas and outlet air through the PLC controller 74. If the temperature difference of the three is not much different, it means that the equipment is operating normally. If the temperature difference of the three exceeds the set threshold range, it indicates that the equipment may have problems such as ash blockage, corrosion, and wear. At this time, the PLC controller 74 controls the sound and light alarm 75 to send an alarm signal to remind the staff to inspect the equipment to avoid large losses. The above-mentioned first temperature sensor 71, the second temperature sensor 72, the third temperature sensor 73, the PLC controller 74 and the sound and light alarm 75 are all existing equipment and will not be described in detail here.

[0042] The utility model effectively solves the problems of corrosion and ash blocking of air preheater, and the device has simple process, low operation difficulty, low investment cost and remarkable economic and social benefits.

[0043] Although the present invention has been specifically demonstrated and described in conjunction with the preferred embodiments, those skilled in the art should understand that various changes may be made to the present invention in form and detail without departing from the spirit and scope of the present invention as defined in the appended claims, all of which are within the scope of protection of the present invention.

Claims

1. An anti-corrosion, anti-blocking, anti-wear air preheater device, comprising a box, characterized in that: The box body includes a smoke inlet, a smoke outlet, an air inlet, an air outlet, a front tube sheet, an intermediate tube sheet, a rear tube sheet, and a plurality of air preheater tubes horizontally arranged in the front tube sheet, the intermediate tube sheet, and the rear tube sheet; the air preheater tubes include a protective tube and a composite heat exchange tube; The protection tubes are evenly arranged side by side in the top area of ​​the air preheater tube; the protection tubes include a first inner steel tube and a first enamel layer arranged on the surface of the first inner steel tube, the front and rear ends of the protection tubes are closed structures, and the front and rear ends of the protection tubes are respectively welded to the front tube sheet and the rear tube sheet; The composite heat exchange tubes are distributed in a matrix at the lower part of the protection tube; the composite heat exchange tubes include a cold end tube section located in the front end area of ​​the box body and a main body tube section located at the rear end of the cold end tube section, the main body tube section includes a second inner steel tube and a second enamel layer arranged on the outer surface of the second inner steel tube, the cold end tube section includes a third inner steel tube and an outer steel tube arranged on the outer surface of the third inner steel tube, and a heat conductive layer is arranged between the inner steel tube and the outer steel tube; the second inner steel tube and the third inner steel tube are connected as one piece; The front end of the composite heat exchange tube is slidably connected to the front tube sheet, and the rear end of the composite heat exchange tube is welded to the rear tube sheet.

2. The anti-corrosion, anti-ash blocking and anti-wear air preheater device according to claim 1 is characterized in that: The number of the intermediate tube sheets is 2.

3. The anti-corrosion, anti-ash blocking and anti-wear air preheater device according to claim 1 is characterized in that: The wall thickness of the first inner steel tube is greater than the wall thickness of the second inner steel tube.

4. The anti-corrosion, anti-ash blocking and anti-wear air preheater device according to claim 1 is characterized in that: The first inner steel pipe, the second inner steel pipe and the third inner steel pipe are made of ND steel, and the outer steel pipe is made of 2205 stainless steel.

5. The anti-corrosion, anti-ash blocking and anti-wear air preheater device according to claim 1 is characterized in that: The thickness of the first enamel layer and the second enamel layer is 0.4 mm-0.5 mm.

6. The anti-corrosion, anti-clogging, anti-wear air preheater device according to claim 1, characterized in that: The length of the cold end pipe section is 600 mm.

7. The anti-corrosion, anti-ash blocking and anti-wear air preheater device according to claim 1 is characterized in that: The composite heat exchange tube and the front tube plate are sealed and connected by a graphite gasket.

8. The anti-corrosion, anti-ash blocking and anti-wear air preheater device according to claim 1 is characterized in that: A heat-resistant gasket is arranged between the air preheater tube and the intermediate tube plate, and the heat-resistant gasket is a fluororubber gasket.

9. The anti-corrosion, anti-ash blocking and anti-wear air preheater device according to claim 1, characterized in that: It also includes a monitoring mechanism, which includes a first temperature sensor, a second temperature sensor, a third temperature sensor, a PLC controller and an audible and visual alarm; the first temperature sensor is arranged at the smoke inlet; the second temperature sensor is arranged at the smoke outlet, and the third temperature sensor is arranged at the air outlet; the first temperature sensor, the second temperature sensor, the third temperature sensor and the audible and visual alarm are all electrically connected to the PLC controller.

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