Anti-ash-blocking control method for air preheater of thermal generator set

Abstract

A thermal generator set air preheater anti-ash-blocking control method comprises the steps that a temperature sensor is installed at the cold end of a rotor, and when a thermal generator set generates electricity according to rated power, a denitration system operates normally and the interior of the rotor is not blocked by accumulated ash, the pressure difference between the hot end and the cold end of the rotor is measured; the temperature sensor is electrically connected with the electrical control system to obtain and record the temperature of the surface of the heat transfer element in the cabin on the cold end side of the rotor when the thermal generator set generates electricity according to rated power, the denitration system operates normally and the interior of the rotor is not blocked by accumulated dust; the normal pressure difference between the rotor hot end and the rotor cold end; and the temperature of the surface of a heat transfer element in a cabin on one side of the rotor cold end. According to the ash blocking prevention control method for the air preheater of the thermal generator set, ash and scale can be reduced or avoided from being accumulated on the inner wall of a bin of the air preheater and the surface of a heat transfer element, and it is ensured that the air preheater of the thermal generator set always keeps efficient heat exchange.

Description

Technical Field

[0001] This invention relates to a method for preventing ash blockage in the air preheater of a thermal power generating unit. Background Technology

[0002] The formation and development of air preheater blockage is influenced by various factors such as boiler load, coal quality changes, ammonia injection rate in the denitrification system, and catalyst activity. Anti-clogging devices installed to address air preheater blockage and low-temperature corrosion can effectively solve this problem. However, during the operation of the anti-clogging device, when the main variable parameters affecting air preheater blockage change, it is necessary to adjust the operation mode of the anti-clogging device in a timely manner to better solve the air preheater blockage problem. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preventing ash blockage in the air preheater of a thermal power generator set, which can reduce or avoid the accumulation of ash and scale on the inner wall of the air preheater and the surface of the heat transfer elements, and ensure that the air preheater of the thermal power generator set always maintains high-efficiency heat exchange.

[0004] The present invention provides a method for preventing ash blockage in the air preheater of a thermal power generating unit, comprising a coal-fired boiler, a denitrification system, and a rotary air preheater. The rotary air preheater includes a rotor rotatably mounted on a frame. One end of the rotor is a hot end, and the other end is a cold end. The hot end of the rotor is provided with a flue gas inlet, a high-pressure primary air outlet, and a low-pressure secondary air outlet. The cold end of the rotor is provided with a flue gas outlet, a high-pressure primary air inlet, and a low-pressure secondary air inlet. The flue gas outlet and the flue gas inlet are connected by a flue gas passage passing through the rotor axially. The high-pressure primary air inlet and the high-pressure primary air outlet are connected by a high-pressure primary air passage passing through the rotor axially. The low-pressure secondary air inlet and the low-pressure secondary air outlet are connected by a low-pressure secondary air passage passing through the rotor axially.

[0005] A flue gas secondary air hot end fan-shaped plate is provided between the flue gas secondary air inlet and the low-pressure secondary air outlet of the rotor, and a flue gas secondary air cold end fan-shaped plate is provided between the flue gas secondary air outlet and the low-pressure secondary air inlet of the rotor.

[0006] A flue gas primary air inter-hot end fan-shaped plate is provided between the flue gas primary air inlet and the high-pressure primary air outlet of the rotor, and a flue gas primary air inter-cold end fan-shaped plate is provided between the flue gas primary air outlet and the high-pressure primary air inlet of the rotor.

[0007] A fan-shaped plate is provided between the low-pressure secondary air outlet and the high-pressure primary air outlet at the hot end of the rotor, and a fan-shaped plate is provided between the low-pressure secondary air inlet and the high-pressure primary air inlet at the cold end of the rotor.

[0008] The rotor is provided with a hot return air duct on its outer side. A circulating hot air fan with adjustable air volume is connected in series on the hot return air duct. The air inlet of the hot return air duct is connected to the high-pressure primary air outlet. The air outlet of the hot return air duct is connected to the cold end of the rotor. The air outlet of the hot return air duct is located between the high-pressure primary air inlet and the cold end fan-shaped plate of the flue gas primary air. The air outlet of the hot return air duct is connected to the high-pressure primary air outlet guide duct through the hot return air channel passing through the rotor along the axial direction.

[0009] The method for preventing ash blockage in the air preheater of a thermal power generating unit includes the following steps:

[0010] A. Install a temperature sensor at the cold end of the rotor. When the thermal power generator set generates electricity at its rated power, the denitrification system operates normally, and the rotor is not blocked by ash accumulation, measure the pressure difference between the hot and cold ends of the rotor, and simultaneously measure the surface temperature of the heat transfer element in the compartment on one side of the cold end of the rotor. The temperature sensor is electrically connected to the electrical control system. Obtain and record the normal pressure difference between the hot and cold ends of the rotor and the surface temperature of the heat transfer element in the compartment on one side of the cold end of the rotor when the thermal power generator set generates electricity at its rated power, the denitrification system operates normally, and the rotor is not blocked by ash accumulation.

[0011] B. The temperature sensor continuously monitors the temperature change of the heat transfer element surface in the compartment on the cold end side of the rotor, and at the same time continuously monitors the pressure difference between the hot end and the cold end of the rotor. When the temperature sensor detects that the lowest temperature of the heat transfer element surface in the compartment on the cold end side of the rotor is lower than 110°C, the temperature sensor sends an electrical signal to the electrical control system, and the electrical control system increases the speed of the circulating hot air fan until the lowest temperature of the cold end of the rotor exceeds 110°C, and then maintains the speed of the circulating hot air fan.

[0012] C. When the pressure difference between the hot and cold ends of the rotor is measured to be greater than the normal pressure difference, the speed of the circulating hot air fan is increased through the electrical control system until the pressure difference between the hot and cold ends of the rotor returns to the normal pressure difference, and then the speed of the circulating hot air fan is reduced back to the original value.

[0013] D. When the temperature sensor detects that the surface temperature of the heat transfer element in the cold end compartment of the rotor is higher than 130°C for 2 consecutive minutes, the temperature sensor sends an electrical signal to the electrical control system to reduce the speed of the circulating hot air fan until the surface temperature of the heat transfer element in the cold end compartment of the rotor drops below 130°C once within 2 consecutive minutes, and then the speed of the circulating hot air fan is maintained.

[0014] The present invention relates to a method for preventing ash blockage in the air preheater of a thermal power generating unit, wherein the thermal power generating unit is a 250MW thermal power generating unit, the rated wind speed at the outlet of the circulating hot air fan is 30m / s, and when the temperature of the outside air is greater than 15℃ and the output power of the thermal power generating unit is equal to or greater than 250MW, the wind speed at the outlet of the circulating hot air fan is controlled within the range of 15-20m / s.

[0015] The present invention relates to a method for preventing ash blockage in the air preheater of a thermal power generator set, wherein the thermal power generator set is a 250MW thermal power generator set, the rated wind speed at the outlet of the circulating hot air fan is 30m / s, and when the temperature of the outside air is greater than 15℃, and the output power of the thermal power generator set is less than 250MW, the wind speed at the outlet of the circulating hot air fan is controlled within the range of 20-25m / s.

[0016] The present invention relates to a method for preventing ash blockage in the air preheater of a thermal power generating unit, wherein the thermal power generating unit is a 250MW thermal power generating unit, the rated wind speed at the outlet of the circulating hot air fan is 30m / s, when the outside air temperature is less than or equal to 15℃ and the output power of the thermal power generating unit is equal to or greater than 250MW, the wind speed at the outlet of the circulating hot air fan is controlled within the range of 20-25m / s; when the output power of the thermal power generating unit is less than 250MW, the wind speed at the outlet of the circulating hot air fan is controlled within the range of 25-30m / s.

[0017] The present invention relates to a method for preventing ash blockage in the air preheater of a thermal power generating unit, wherein when the 250MW thermal power generating unit generates electricity at its rated power, and the ammonia escape from the denitrification system is greater than 10ppm, the wind speed at the outlet of the hot air blower of the hot circulation system is controlled within the range of 25-30m / s.

[0018] The present invention provides a method for preventing ash blockage in the air preheater of a thermal power generating unit. When the 250MW thermal power generating unit generates electricity at its rated power, and the ammonia injection rate of the denitrification system is greater than the normal level and exceeds 20%, the wind speed at the outlet of the hot air blower of the hot circulation system is controlled within the range of 25-30m / s.

[0019] The present invention relates to a method for preventing ash blockage in the air preheater of a thermal power generating unit, wherein a hot return air guide cover is provided at the air outlet of the hot return air duct.

[0020] The present invention relates to a method for preventing ash blockage in the air preheater of a thermal power generator set, wherein the rotor axis is located in the vertical direction, the flue gas outlet is located below the flue gas inlet, the high-pressure primary air inlet is located below the high-pressure primary air outlet, and the low-pressure secondary air inlet is located below the low-pressure secondary air outlet.

[0021] The present invention relates to a method for preventing ash blockage in the air preheater of a thermal power generating unit, wherein a smoke inlet guide hood is provided at the smoke inlet, a high-pressure primary air outlet guide hood is provided at the high-pressure primary air outlet, a low-pressure secondary air outlet guide hood is provided at the low-pressure secondary air outlet, a smoke outlet guide hood is provided at the smoke outlet, a high-pressure primary air inlet guide hood is provided at the high-pressure primary air inlet, a low-pressure secondary air inlet guide hood is provided at the low-pressure secondary air inlet, and the air inlet of the hot return air duct is connected to the high-pressure primary air outlet through a high-pressure primary air outlet guide hood or a high-pressure primary air outlet guide duct.

[0022] The present invention relates to a method for preventing ash blockage in the air preheater of a thermal power generating unit, wherein the flue gas inlet, the high-pressure primary air outlet, the low-pressure secondary air outlet, the flue gas outlet, the high-pressure primary air inlet, and the low-pressure secondary air inlet are all fan-shaped.

[0023] The present invention relates to a method for preventing ash blockage in the air preheater of a thermal power generating unit, wherein a fan-shaped plate for the hot return air channel is provided between the air inlet of the hot return air channel and the high-pressure primary air inlet, and the air inlet of the hot return air channel is fan-shaped.

[0024] The present invention relates to a method for preventing ash blockage in the air preheater of a thermal power generating unit, wherein a valve for adjusting the air volume is connected in series on the hot return air duct.

[0025] The method for preventing ash blockage in the air preheater of a thermal power generating unit according to the present invention includes the following steps:

[0026] A. Install a temperature sensor at the cold end of the rotor. When the thermal power generator set generates electricity at its rated power, and the denitrification system 21 is operating normally, and the rotor is not blocked by ash accumulation, measure the pressure difference between the hot end and the cold end of the rotor, and simultaneously measure the surface temperature of the heat transfer element in the compartment on one side of the cold end of the rotor. The temperature sensor is electrically connected to the electrical control system. Obtain and record the normal pressure difference between the hot end and the cold end of the rotor and the surface temperature of the heat transfer element in the compartment on one side of the cold end of the rotor when the thermal power generator set generates electricity at its rated power, the denitrification system is operating normally, and the rotor is not blocked by ash accumulation.

[0027] B. The temperature sensor continuously monitors the temperature change of the heat transfer element surface in the cold end compartment of the rotor, while simultaneously monitoring the pressure difference between the hot and cold ends of the rotor. When the temperature sensor detects that the minimum temperature of the heat transfer element surface in the cold end compartment is below 110°C, it sends an electrical signal to the electrical control system. The electrical control system then increases the speed of the circulating hot air fan until the minimum temperature of the cold end of the rotor exceeds 110°C, and then maintains the speed of the circulating hot air fan. This ensures that the temperature of the cold end of the rotor is always maintained above 110°C. When the rotor enters the flue gas passage, because the temperature of the cold end of the rotor is always maintained above 110°C, condensable substances in the flue gas cannot condense on the inner wall of the compartment and on the heat transfer elements located in the compartment, preventing dust and scale from accumulating on their surfaces.

[0028] C. When the pressure difference between the hot and cold ends of the rotor is measured to be greater than the normal pressure difference, the speed of the circulating hot air fan is increased through the electrical control system until the pressure difference between the hot and cold ends of the rotor returns to the normal pressure difference, and then the speed of the circulating hot air fan is reduced back to the original value.

[0029] D. When the temperature sensor detects that the surface temperature of the heat transfer element in the cold end compartment of the rotor is higher than 130°C for 2 consecutive minutes, the temperature sensor sends an electrical signal to the electrical control system to reduce the speed of the circulating hot air fan until the surface temperature of the heat transfer element in the cold end compartment of the rotor drops below 130°C once within 2 consecutive minutes, and then the speed of the circulating hot air fan is maintained.

[0030] Therefore, the anti-fouling control method for air preheaters of thermal power generator sets of the present invention can reduce or avoid the accumulation of ash and scale on the inner wall of the air preheater and the surface of the heat transfer elements, ensuring that the air preheater of the thermal power generator set always maintains high-efficiency heat exchange, improving the heat exchange efficiency and service life of the equipment, avoiding energy waste, and reducing the number of manual cleanings and reducing the labor intensity of workers.

[0031] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of a thermal power generator set for which the anti-ash blockage control method for the air preheater of the thermal power generator set of the present invention can be used;

[0033] Figure 2 This is a perspective view from bottom to top of the method for preventing ash blockage in the air preheater of a thermal power generating unit according to the present invention.

[0034] Figure 3 The above is a perspective view from bottom to top of the method for preventing ash blockage in the air preheater of a thermal power generator set, which removes the hot return air guide cover.

[0035] Figure 4 This is a top-down perspective view of the method for preventing ash blockage in the air preheater of a thermal power generating unit according to the present invention. Detailed Implementation

[0036] like Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, the method for preventing ash blockage in the air preheater of a thermal power generating unit according to the present invention includes a coal-fired boiler 20, a denitrification system 21, and a rotary air preheater 22. The rotary air preheater 21 includes a rotor 1, which is rotatably mounted on a frame. One end of the rotor 1 is a hot end and the other end is a cold end. The hot end of the rotor 1 is provided with a flue gas inlet 3, a high-pressure primary air outlet 4, and a low-pressure secondary air outlet 5. The cold end of the rotor 1 is provided with a flue gas outlet 6, a high-pressure primary air inlet 7, and a low-pressure secondary air inlet 8. The flue gas outlet 6 is connected to the flue gas inlet 3 through a flue gas passage passing through the rotor 1 axially. The high-pressure primary air inlet 7 is connected to the high-pressure primary air outlet 4 through a high-pressure primary air passage passing through the rotor 1 axially. The low-pressure secondary air inlet 8 is connected to the low-pressure secondary air outlet 5 through a low-pressure secondary air passage passing through the rotor 1 axially.

[0037] A flue gas secondary air hot end fan-shaped plate 9 is provided between the flue gas secondary air hot end fan-shaped plate 9 and the low pressure secondary air outlet 5 at the hot end of the rotor 1, and a flue gas secondary air cold end fan-shaped plate 10 is provided between the flue gas secondary air cold end fan-shaped plate 10 and the flue gas secondary air cold end fan-shaped plate 10 at the cold end of the rotor 1.

[0038] A flue gas primary air hot end fan-shaped plate 11 is provided between the flue gas primary air hot end fan-shaped plate 3 at the hot end of rotor 1 and the high pressure primary air outlet 4, and a flue gas primary air cold end fan-shaped plate 12 is provided between the flue gas primary air cold end fan-shaped plate 12 at the cold end fan-shaped plate 6 at the cold end of rotor 1 and the high pressure primary air inlet 7.

[0039] A fan-shaped plate 15 for hot end of low-pressure secondary air outlet 5 and high-pressure primary air outlet 4 is provided between the low-pressure secondary air outlet 5 and the high-pressure primary air outlet 4 of rotor 1, and a fan-shaped plate 16 for cold end of low-pressure secondary air inlet 8 and high-pressure primary air inlet 7 of rotor 1 is provided between the low-pressure secondary air inlet 8 and the high-pressure primary air inlet 7 of rotor 1.

[0040] The rotor 1 is provided with a hot return air duct 14 on its outer side. A circulating hot air fan 13 with adjustable air volume is connected in series on the hot return air duct 14. The air inlet of the hot return air duct 14 is connected to the high-pressure primary air outlet 4. The air outlet of the hot return air duct 14 is connected to the cold end of the rotor 1. The air outlet of the hot return air duct 14 is located between the high-pressure primary air inlet 7 and the cold end fan-shaped plate 12 of the flue gas primary air. The air outlet of the hot return air duct 14 is connected to the high-pressure primary air outlet guide pipe through the hot return air channel 18 that passes through the rotor 1 axially.

[0041] The method for preventing ash blockage in the air preheater of a thermal power generating unit includes the following steps:

[0042] A. Install a temperature sensor at the cold end of rotor 1. When the thermal power generator set generates electricity at the rated power, the denitrification system 21 operates normally, and the rotor 1 is not blocked by ash accumulation, measure the pressure difference between the hot end and the cold end of rotor 1, and measure the surface temperature of the heat transfer element in the compartment on the cold end side of rotor 1. The temperature sensor is electrically connected to the electrical control system. Obtain and record the normal pressure difference between the hot end and the cold end of rotor 1 and the surface temperature of the heat transfer element in the compartment on the cold end side of rotor 1 when the thermal power generator set generates electricity at the rated power, the denitrification system operates normally, and the rotor 1 is not blocked by ash accumulation.

[0043] B. The temperature sensor continuously monitors the temperature change of the heat transfer element surface in the cold end compartment of the rotor, and simultaneously monitors the pressure difference between the hot and cold ends of rotor 1. When the temperature sensor detects that the minimum temperature of the heat transfer element surface in the cold end compartment of the rotor is below 110°C, the temperature sensor sends an electrical signal to the electrical control system. The electrical control system then increases the speed of the circulating hot air fan 13 until the minimum temperature of the rotor cold end exceeds 110°C, and then maintains the speed of the circulating hot air fan 13. This ensures that the temperature of the rotor cold end is always maintained above 110°C. When the rotor enters the flue gas passage, because the temperature of the rotor cold end is always maintained above 110°C, condensable substances in the flue gas cannot condense on the inner wall of the compartment and on the heat transfer elements located in the compartment, preventing dust and scale from accumulating on their surfaces.

[0044] C. When the pressure difference between the hot end and the cold end of rotor 1 is measured to be greater than the normal pressure difference, the speed of the circulating hot air fan 13 is increased through the electrical control system until the pressure difference between the hot end and the cold end of rotor 1 returns to the normal pressure difference, and then the speed of the circulating hot air fan 13 is reduced to the original value.

[0045] D. When the temperature sensor detects that the surface temperature of the heat transfer element in the cold end compartment of the rotor is higher than 130°C for two consecutive minutes, the temperature sensor sends an electrical signal to the electrical control system to reduce the speed of the circulating hot air fan 13 until the surface temperature of the heat transfer element in the cold end compartment of the rotor drops below 130°C once within two consecutive minutes, and then maintains the same speed of the circulating hot air fan 13. This ensures that the temperature of the rotor's cold end is always kept below 130°C. Because the temperature of the rotor's cold end is always kept below 130°C, the rotor's heat can be utilized efficiently.

[0046] As a further improvement of the present invention, the thermal power generator set is a 250MW thermal power generator set, and the rated wind speed at the outlet of the circulating hot air fan 13 is 30m / s. When the temperature of the outside air is greater than 15℃ and the output power of the thermal power generator set is equal to or greater than 250MW, it is necessary to adjust the wind speed at the outlet of the circulating hot air fan 13 in a timely manner to prevent ammonium bisulfate and dilute sulfuric acid from condensing in the rotary air preheater 22. In this case, the wind speed at the outlet of the circulating hot air fan 13 can be controlled within the range of 15-20m / s.

[0047] As a further improvement of the present invention, the thermal power generator set is a 250MW thermal power generator set, and the rated wind speed at the outlet of the circulating hot air fan 13 is 30m / s. When the temperature of the outside air is greater than 15℃, and the output power of the thermal power generator set is less than 250MW, it is necessary to adjust the wind speed at the outlet of the circulating hot air fan 13 in time to prevent ammonium bisulfate and dilute sulfuric acid from condensing in the rotary air preheater 22. In this case, the wind speed at the outlet of the circulating hot air fan 13 can be controlled within the range of 20-25m / s.

[0048] As a further improvement of the present invention, the thermal power generator set is a 250MW thermal power generator set, and the rated wind speed at the outlet of the circulating hot air fan 13 is 30m / s. When the temperature of the outside air is less than or equal to 15℃ and the output power of the thermal power generator set is equal to or greater than 250MW, it is necessary to adjust the wind speed at the outlet of the circulating hot air fan 13 in a timely manner to prevent ammonium bisulfate and dilute sulfuric acid from condensing in the rotary air preheater 22. In this case, the wind speed at the outlet of the circulating hot air fan 13 can be controlled within the range of 20-25m / s. When the output power of the thermal power generator set is less than 250MW, the wind speed at the outlet of the circulating hot air fan 13 is controlled within the range of 25-30m / s.

[0049] As a further improvement of the present invention, when the 250MW thermal power generating unit generates electricity at the rated power, and the ammonia escape from the denitrification system 21 is greater than 10ppm, it is necessary to adjust the wind speed at the outlet of the hot air blower 13 in a timely manner to prevent ammonium bisulfate and dilute sulfuric acid from condensing in the rotary air preheater 22. In this case, the wind speed at the outlet of the hot air blower 13 can be controlled within the range of 25-30m / s.

[0050] As a further improvement of the present invention, when the 250MW thermal power generating unit generates electricity at the rated power, and at the same time the ammonia injection of the denitrification system is greater than the normal level and the amount of the excess exceeds 20%, it is necessary to increase the wind speed at the outlet of the hot air blower 13 in a timely manner to prevent ammonium bisulfate and dilute sulfuric acid from condensing in the rotary air preheater 22. In this case, the wind speed at the outlet of the hot air blower 13 can be controlled within the range of 25-30m / s.

[0051] During the operation of the coal-fired boiler 20, the denitrification system 21 is located at the front end. The denitrification system 21 injects ammonia into the flue gas, where, under the action of a catalyst, the ammonia reacts with the nitrogen oxides in the flue gas to ensure compliance with the flue gas pollutant emission standards. However, when the flue gas flows through the denitrification system 21, the concentrations of SO3 and NH3 in the flue gas increase. The ammonium bisulfate and dilute sulfuric acid produced by the reaction condense into highly viscous substances in the rotary air preheater 22, causing blockage of the heat storage components of the rotary air preheater 22. This increases the differential pressure of the rotary air preheater 22, affecting the high-efficiency operation of the generator set. In this case, it is necessary to promptly increase the wind speed at the outlet of the hot air blower 13 of the hot air circulation system to prevent the condensation of ammonium bisulfate and dilute sulfuric acid in the rotary air preheater 22.

[0052] As a further improvement of the present invention, a hot return air guide cover 17 is provided at the air outlet of the hot return air duct 14.

[0053] As a further improvement of the present invention, the axis of the rotor 1 is located in the vertical direction, the smoke outlet 6 is located below the smoke inlet 3, the high-pressure primary air inlet 7 is located below the high-pressure primary air outlet 4, and the low-pressure secondary air inlet 8 is located below the low-pressure secondary air outlet 5.

[0054] As a further improvement of the present invention, a smoke inlet guide hood is provided at the smoke inlet 3, a high-pressure primary air outlet guide hood is provided at the high-pressure primary air outlet 4, a low-pressure secondary air outlet guide hood is provided at the low-pressure secondary air outlet 5, a smoke outlet guide hood is provided at the smoke outlet 6, a high-pressure primary air inlet guide hood is provided at the high-pressure primary air inlet 7, a low-pressure secondary air inlet guide hood is provided at the low-pressure secondary air inlet 8, and the air inlet of the hot return air duct 14 is connected to the high-pressure primary air outlet 4 through the high-pressure primary air outlet guide hood or the high-pressure primary air outlet guide duct.

[0055] As a further improvement of the present invention, the above-mentioned smoke inlet 3, high-pressure primary air outlet 4, low-pressure secondary air outlet 5, smoke outlet 6, high-pressure primary air inlet 7, and low-pressure secondary air inlet 8 are all fan-shaped.

[0056] As a further improvement of the present invention, a fan-shaped heat return air duct 18 is provided between the air inlet (i.e., the air outlet of the heat return air duct 14) and the high-pressure primary air inlet 7, wherein the air inlet of the heat return air duct 18 is fan-shaped. The fan-shaped heat return air duct 18 is mounted and connected to the frame (not shown in the figure).

[0057] As a further improvement of the present invention, a valve (not shown in the figure) for adjusting the air volume is connected in series on the hot return air duct 14.

[0058] The fact that the air inlet of the hot return air duct 14 is connected to the high-pressure primary air outlet 4 means that the hot air coming out of the high-pressure primary air outlet 4 can flow into the hot return air duct 14 under the suction action of the circulating hot air fan 13. This includes the hot air inlet of the hot return air duct 14 being near the high-pressure primary air outlet 4, directly drawing away the hot air discharged from the high-pressure primary air outlet 4 from outside the high-pressure primary air outlet 4, and also includes not drawing away the air directly from the high-pressure primary air outlet 4, but drawing away the hot air coming out of the high-pressure primary air outlet 4 from the high-pressure primary air outlet guide duct that guides the hot air into the boiler.

[0059] The outlet of the aforementioned hot return air duct 14 is connected to the high-pressure primary air outlet guide duct located outside the high-pressure primary air outlet 4 via the hot return air channel 18 that passes through the rotor 1 axially. This means that the air coming out of the outlet of the hot return air duct 14 can flow into the high-pressure primary air outlet guide duct of the boiler through the hot return air channel 18 under the exhaust action of the circulating hot air fan 13. This includes the outlet of the hot return air duct 14 being directly connected to the cavity near the high-pressure primary air outlet 4 through the hot return air channel 18, allowing the air coming out of the outlet of the hot return air duct 14 and the hot return air channel 18 to enter the high-pressure primary air outlet guide duct of the boiler from the vicinity of the high-pressure primary air outlet 4. It also includes the air coming out of the outlet of the hot return air duct 14 not coming out of the high-pressure primary air outlet 4, but directly entering the high-pressure primary air outlet guide duct of the boiler, and the air coming out of the outlet of the hot return air duct 14 and the hot return air channel 18 being drawn away from the high-pressure primary air outlet guide duct.

[0060] In the operation of the air preheater anti-ash blockage control method of the thermal power generator set of the present invention, the rotor 1 rotates under the drive of the motor. The flue gas with a large amount of heat enters the flue gas channel through the flue gas inlet 3 at the hot end of the rotor 1, heating the heat transfer elements rotating through each compartment in the flue gas channel 3, causing the temperature of the heat transfer elements to rise rapidly. Then the flue gas leaves the flue gas channel through the flue gas outlet 6 at the cold end of the rotor 1. When the heated heat transfer elements rotate into the low-pressure secondary air channel 4 and the high-pressure primary air channel 5, the air entering the low-pressure secondary air channel through the low-pressure secondary air inlet 8 at the cold end of the rotor 1 and the air entering the high-pressure primary air channel through the high-pressure primary air inlet 7 at the cold end of the rotor 1 will be heated by the heat transfer elements, thereby transferring the heat in the flue gas to the air passing through the low-pressure secondary air channel and the high-pressure primary air channel.

[0061] A small portion of the hot air exiting the high-pressure primary air duct is drawn into the inlet of the hot return air duct 14 by the circulating hot air fan 13, and then enters the hot return air channel 18 through the outlet of the hot return air duct 14. During this process—when the hot air in the hot return air duct 14 is transported into the hot return air channel 18 by the circulating hot air fan 13—the hot air enters the hot return air channel 18 through the hot return air duct 14, heating each compartment on the rotating rotor 1 that passes through the hot return air channel 18. The heat transfer elements located in the chamber allow the temperature of the cold end of the rotor 1, which is about to rotate into the flue gas passage, to rise in advance. When the rotor 1 enters the flue gas passage, the high temperature of the cold end of the rotor 1 prevents condensable substances in the flue gas from condensing on the inner wall of the chamber and the heat transfer elements located in the chamber. In addition, the circulating hot airflow passing through the hot return air passage 18 at high speed blows away any dust and dirt that may be present on the inner wall of the chamber and the heat transfer elements located in the chamber, preventing dust and dirt from accumulating on their surfaces.

[0062] The method for preventing ash blockage in the air preheater of a thermal power generating unit includes the following steps:

[0063] A. Install a temperature sensor at the cold end of the rotor (1). When the thermal power generator set generates electricity at the rated power, and the denitrification system 21 is operating normally, and the rotor (1) is not blocked by ash, measure the pressure difference between the hot end and the cold end of the rotor (1), and measure the temperature of the heat transfer element surface in the compartment on the cold end side of the rotor (1). The temperature sensor is electrically connected to the electrical control system to obtain and record the normal pressure difference between the hot end and the cold end of the rotor (1) and the temperature of the heat transfer element surface in the compartment on the cold end side of the rotor (1) when the thermal power generator set generates electricity at the rated power, the denitrification system is operating normally, and the rotor (1) is not blocked by ash.

[0064] B. Allow the temperature sensor to continuously monitor the temperature change of the heat transfer element surface in the compartment on the cold end side of the rotor, and at the same time continuously monitor the pressure difference between the hot end and the cold end of the rotor (1). When the temperature sensor detects that the lowest temperature of the heat transfer element surface in the compartment on the cold end side of the rotor is lower than 110°C, allow the temperature sensor to send an electrical signal to the electrical control system, and increase the speed of the circulating hot air fan (13) through the electrical control system until the lowest temperature of the cold end of the rotor exceeds 110°C, and then maintain the speed of the circulating hot air fan (13).

[0065] C. When the pressure difference between the hot end and the cold end of the rotor (1) is measured to be greater than the normal pressure difference, the speed of the circulating hot air blower (13) is increased through the electrical control system until the pressure difference between the hot end and the cold end of the rotor (1) returns to the normal pressure difference, and then the speed of the circulating hot air blower (13) is reduced to the original value.

[0066] D. When the temperature sensor detects that the temperature of the heat transfer element surface in the cold end chamber of the rotor is higher than 130°C for 2 consecutive minutes, the temperature sensor sends an electrical signal to the electrical control system to reduce the speed of the circulating hot air fan (13) until the temperature of the heat transfer element surface in the cold end chamber of the rotor drops below 130°C once in 2 consecutive minutes, and then maintains the speed of the circulating hot air fan (13).

[0067] Therefore, the anti-fouling control method for air preheaters of thermal power generator sets of the present invention can reduce or avoid the accumulation of ash and scale on the inner wall of the air preheater and the surface of the heat transfer elements, ensuring that the air preheater of the thermal power generator set always maintains high-efficiency heat exchange, improving the heat exchange efficiency and service life of the equipment, avoiding energy waste, and reducing the number of manual cleanings and reducing the labor intensity of workers.

[0068] The use of this invention is related to the rotation direction of rotor 1. This invention requires that the heat transfer element on rotor 1 preferably enters the flue gas passage directly after leaving the hot return air passage 18, rather than the heat transfer element on rotor 1 entering the low-pressure secondary air passage after leaving the hot return air passage 18.

[0069] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preventing ash blockage in the air preheater of a thermal power generating unit, characterized in that: The system includes a coal-fired boiler, a denitrification system and a rotary air preheater. The rotary air preheater includes a rotor (1), which is rotatably mounted on a frame. One end of the rotor (1) is a hot end and the other end is a cold end. The hot end of the rotor (1) is provided with a flue gas inlet (3), a high-pressure primary air outlet (4) and a low-pressure secondary air outlet (5). The cold end of the rotor (1) is provided with a flue gas outlet (6), a high-pressure primary air inlet (7) and a low-pressure secondary air inlet (8). The flue gas outlet (6) and the flue gas inlet (3) are connected through a flue gas passage that passes through the rotor (1) axially. The high-pressure primary air inlet (7) and the high-pressure primary air outlet (4) are connected through a high-pressure primary air passage that passes through the rotor (1) axially. The low-pressure secondary air inlet (8) and the low-pressure secondary air outlet (5) are connected through a low-pressure secondary air passage that passes through the rotor (1) axially. A flue gas secondary air hot end fan-shaped plate (9) is provided between the flue gas secondary air hot end inlet (3) and the low-pressure secondary air outlet (5) of the rotor (1), and a flue gas secondary air cold end fan-shaped plate (10) is provided between the flue gas secondary air cold end inlet (6) and the low-pressure secondary air inlet (8) of the rotor (1). A flue gas primary air hot end fan-shaped plate (11) is provided between the flue gas primary air hot end inlet (3) and the high pressure primary air outlet (4) of the rotor (1), and a flue gas primary air cold end fan-shaped plate (12) is provided between the flue gas primary air cold end inlet (6) and the high pressure primary air inlet (7) of the rotor (1). A fan-shaped plate (15) is provided between the low-pressure secondary air outlet (5) and the high-pressure primary air outlet (4) at the hot end of the rotor (1), and a fan-shaped plate (16) is provided between the low-pressure secondary air inlet (8) and the high-pressure primary air inlet (7) at the cold end of the rotor (1). The rotor (1) is provided with a hot return air duct (14) on the outside. A circulating hot air fan (13) with adjustable air volume is connected in series on the hot return air duct (14). The air inlet of the hot return air duct (14) is connected to the high pressure primary air outlet (4). The air outlet of the hot return air duct (14) is connected to the cold end of the rotor (1). The air outlet of the hot return air duct (14) is located between the high pressure primary air inlet (7) and the cold end fan-shaped plate (12) of the flue gas primary air. The air outlet of the hot return air duct (14) is connected to the high pressure primary air outlet guide pipe through the hot return air channel (18) that passes through the rotor (1) axially. The method for preventing ash blockage in the air preheater of a thermal power generating unit includes the following steps: A. Install a temperature sensor at the cold end of the rotor (1). When the thermal power generator set generates electricity at the rated power, and the denitrification system is operating normally, and the rotor (1) is not blocked by ash, measure the pressure difference between the hot end and the cold end of the rotor (1), and measure the temperature of the heat transfer element surface in the compartment on the cold end side of the rotor (1). The temperature sensor is electrically connected to the electrical control system to obtain and record the normal pressure difference between the hot end and the cold end of the rotor (1) and the temperature of the heat transfer element surface in the compartment on the cold end side of the rotor (1) when the thermal power generator set generates electricity at the rated power, the denitrification system is operating normally, and the rotor (1) is not blocked by ash. B. Allow the temperature sensor to continuously monitor the temperature change of the heat transfer element surface in the compartment on the cold end side of the rotor, and at the same time continuously monitor the pressure difference between the hot end and the cold end of the rotor (1). When the temperature sensor detects that the lowest temperature of the heat transfer element surface in the compartment on the cold end side of the rotor is lower than 110°C, allow the temperature sensor to send an electrical signal to the electrical control system, and increase the speed of the circulating hot air fan (13) through the electrical control system until the lowest temperature of the cold end of the rotor exceeds 110°C, and then maintain the speed of the circulating hot air fan (13). C. When the pressure difference between the hot end and the cold end of the rotor (1) is measured to be greater than the normal pressure difference, the speed of the circulating hot air blower (13) is increased through the electrical control system until the pressure difference between the hot end and the cold end of the rotor (1) returns to the normal pressure difference, and then the speed of the circulating hot air blower (13) is reduced to the original value. D. When the temperature sensor detects that the temperature of the heat transfer element surface in the cold end chamber of the rotor is higher than 130°C for 2 consecutive minutes, the temperature sensor sends an electrical signal to the electrical control system to reduce the speed of the circulating hot air fan (13) until the temperature of the heat transfer element surface in the cold end chamber of the rotor drops below 130°C once in 2 consecutive minutes, and then maintains the speed of the circulating hot air fan (13).

2. The method for preventing ash blockage in the air preheater of a thermal power generating unit according to claim 1, characterized in that: The thermal power generator set is a 250MW thermal power generator set. The rated wind speed at the outlet of the circulating hot air fan (13) is 30m / s. When the temperature of the outside air is greater than 15℃ and the output power of the thermal power generator set is equal to or greater than 250MW, the wind speed at the outlet of the circulating hot air fan (13) is controlled within the range of 15-20m / s.

3. The method for preventing ash blockage in the air preheater of a thermal power generating unit according to claim 1, characterized in that: The thermal power generator set is a 250MW thermal power generator set. The rated wind speed at the outlet of the circulating hot air fan (13) is 30m / s. When the temperature of the outside air is greater than 15℃, and when the output power of the thermal power generator set is less than 250MW, the wind speed at the outlet of the circulating hot air fan (13) is controlled within the range of 20-25m / s.

4. The method for preventing ash blockage in the air preheater of a thermal power generating unit according to claim 1, characterized in that: The thermal power generator set is a 250MW thermal power generator set. The rated wind speed at the outlet of the circulating hot air fan (13) is 30m / s. When the temperature of the outside air is less than or equal to 15℃ and the output power of the thermal power generator set is equal to or greater than 250MW, the wind speed at the outlet of the circulating hot air fan (13) is controlled within the range of 20-25m / s. When the output power of the thermal power generator set is less than 250MW, the wind speed at the outlet of the circulating hot air fan (13) is controlled within the range of 25-30m / s.

5. The method for preventing ash blockage in the air preheater of a thermal power generating unit according to claim 2, characterized in that: When the 250MW thermal power generating unit generates electricity at its rated power, and the ammonia escape from the denitrification system is greater than 10ppm, the wind speed at the outlet of the hot air blower (13) of the hot air circulation system is controlled within the range of 25-30m / s.

6. The method for preventing ash blockage in the air preheater of a thermal power generating unit according to claim 2, characterized in that: When the 250MW thermal power generating unit generates electricity at its rated power, and the ammonia injection rate of the denitrification system is greater than the normal level and exceeds 20%, the wind speed at the outlet of the hot air blower (13) of the hot air circulation system is controlled within the range of 25-30m / s.

7. The method for preventing ash blockage in the air preheater of a thermal power generating unit according to any one of claims 1 to 6, characterized in that: The hot return air duct (14) is provided with a hot return air guide cover (17) at the air outlet.

8. The method for preventing ash blockage in the air preheater of a thermal power generating unit according to claim 7, characterized in that: The axis of the rotor (1) is in the vertical direction, the smoke outlet (6) is below the smoke inlet (3), the high-pressure primary air inlet (7) is below the high-pressure primary air outlet (4), and the low-pressure secondary air inlet (8) is below the low-pressure secondary air outlet (5).

9. The method for preventing ash blockage in the air preheater of a thermal power generating unit according to claim 8, characterized in that: The smoke inlet (3) is provided with a smoke inlet guide hood, the high-pressure primary air outlet (4) is provided with a high-pressure primary air outlet guide hood, the low-pressure secondary air outlet (5) is provided with a low-pressure secondary air outlet guide hood, the smoke outlet (6) is provided with a smoke outlet guide hood, the high-pressure primary air inlet (7) is provided with a high-pressure primary air inlet guide hood, and the low-pressure secondary air inlet (8) is provided with a low-pressure secondary air inlet guide hood. The air inlet of the hot return air duct (14) is connected to the high-pressure primary air outlet (4) through the high-pressure primary air outlet guide hood or the high-pressure primary air outlet guide duct.

10. The method for preventing ash blockage in the air preheater of a thermal power generating unit according to claim 9, characterized in that: The smoke inlet (3), high-pressure primary air outlet (4), low-pressure secondary air outlet (5), smoke outlet (6), high-pressure primary air inlet (7), and low-pressure secondary air inlet (8) are all fan-shaped.

11. The method for preventing ash blockage in the air preheater of a thermal power generating unit according to claim 10, characterized in that: A fan-shaped plate (2) is provided between the air inlet of the hot return air channel (18) and the high-pressure primary air inlet (7), and the air inlet of the hot return air channel (18) is fan-shaped.

12. The method for preventing ash blockage in the air preheater of a thermal power generating unit according to claim 11, characterized in that: A valve for adjusting the air volume is connected in series on the hot return air duct (14).

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