Dust remover inlet flue gas parameter leveling system based on combination of smoke cooler and air heater

Abstract

The application discloses a dust remover entrance flue gas parameter leveling system based on combination of a smoke cooler and a warm air heater, which branches the air preheater outlet flue into two or more than two dust remover entrance branch flues along the width direction; at least in the dust remover entrance branch flue with the highest temperature, a smoke cooler, a first flue gas temperature measuring point and a first flue gas flow measuring point are simultaneously installed, the first flue gas temperature measuring point is arranged downstream of the smoke cooler; in the rest of the dust remover entrance branch flues, a flue gas resistance balance adjusting door, a second flue gas temperature measuring point and a second flue gas flow measuring point are simultaneously installed; each dust remover entrance branch flue is connected to the dust remover entrance; based on the feedback values of the first flue gas flow measuring point and the second flue gas flow measuring point and the feedback values of the first flue gas temperature measuring point and the second flue gas temperature measuring point, the opening degree of each flue gas resistance balance door and the liquid water flow in the smoke cooler are adjusted, so that the flow and the temperature in each dust remover entrance branch flue are basically consistent. The application is simple and practical.

Description

Technical Field

[0001] This invention relates to a flue gas parameter leveling system for a dust collector inlet based on a combination of a flue gas cooler and a blower, belonging to the field of waste heat utilization technology for coal-fired power plant boilers. Background Technology

[0002] Nationwide, most coal-fired power units have undergone flue gas cooler retrofitting. Under the background of frequent deep peak shaving, many common problems have been exposed: ash accumulation, wear, leakage, corrosion, etc. Taking a large power generation group as an example, about 80% of the units have undergone flue gas cooler retrofitting, of which 87.4% of the low-temperature economizers have faults (Note: faults refer to obvious corrosion, wear, or ash accumulation problems in the unit).

[0003] Large coal-fired power plants are generally equipped with rotary air preheaters. Flue gas coolers are installed in the flue between the air preheater and the dust collector, covering the entire cross-section of the flue. The heat absorbed by the coolers is sent to the air-side heaters of the air preheater or the turbine-side regenerative system, resulting in a high overall cost. However, due to the rotational heat exchange characteristics of the air preheater rotor's heat storage elements, the flue gas temperature distribution in the air preheater outlet flue is not uniform. The air preheater outlet flue is generally rectangular, with a temperature difference of about 30°C between the two sides along its width. This characteristic causes uneven heat exchange in the uniformly distributed coolers within the flue. Areas with low flue gas temperatures not only have low heat exchange but are also prone to low-temperature corrosion. Localized corrosion and leakage can lead to localized blockages, further increasing the flue gas velocity in non-blocked areas and exacerbating wear. Ultimately, this results in low efficiency and poor operational reliability of traditional coolers. Especially during the low-load operation phase of coal-fired power units, the flue gas temperature at the air preheater outlet is relatively low, and the heat exchange of the flue gas cooler is relatively small. If there is also a blockage problem at this time, its resistance will be significantly higher, which may ultimately lead to negative benefits.

[0004] In addition, the above-mentioned problems also cause a great degree of unevenness in the flue gas flow rate and flue gas temperature at the dust collector inlet, which in turn leads to a decrease in the efficiency of the dust collector; if a bag dust collector is used, it may also easily cause problems such as a shortened life of the filter bags. Summary of the Invention

[0005] In order to reduce the cost of flue gas coolers in coal-fired power units, improve their operating efficiency and reliability, and enhance the uniformity of flue gas flow and temperature at the dust collector inlet, this invention provides a dust collector inlet flue gas parameter leveling system based on the combination of a flue gas cooler and a heater.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: Based on the dust collector inlet flue gas parameter leveling system that combines flue gas cooler and air heater, the air preheater outlet flue is branched into two or more dust collector inlet branch flues along the width direction. At least one flue gas cooler, a first flue gas temperature measuring point and a first flue gas flow measuring point shall be installed simultaneously in the inlet branch flue of the dust collector with the highest temperature. The first flue gas temperature measuring point in the same inlet branch flue of the dust collector shall be set downstream of the flue gas cooler. All other dust collector inlet branch flues are simultaneously equipped with flue gas resistance balancing regulating valves, second flue gas temperature measuring points, and second flue gas flow measuring points. Each dust collector inlet branch flue is connected to the dust collector inlet; Based on the feedback values ​​of the first and second flue gas flow measurement points, as well as the feedback values ​​of the first and second flue gas temperature measurement points, the opening degree of each flue gas resistance balancing valve and the flow rate of liquid water in the flue gas cooler are adjusted so that the flow deviation in each dust collector inlet branch flue is less than 10% of the average flow, and the flue gas temperature deviation in each dust collector inlet branch flue is less than 5℃.

[0007] The direction of this application from upstream to downstream is consistent with the direction of flue gas flow.

[0008] The above-mentioned flue gas cooler is cooled by water, and the water after absorbing heat can be used to heat the cold air in the air preheater, realizing the recycling of heat.

[0009] The aforementioned "other dust collector inlet branch flues" refer to dust collector inlet branch flues that do not have flue gas coolers installed. That is, at least one dust collector inlet branch flue with the highest temperature in this application is equipped with a flue gas cooler, a first flue gas temperature measuring point, and a first flue gas flow measuring point; while the other dust collector inlet branch flues are equipped with a flue gas resistance balancing regulating damper, a second flue gas temperature measuring point, and a second flue gas flow measuring point.

[0010] The aforementioned dust collector inlet flue gas parameter balancing system, based on the combination of a flue gas cooler and a heater, branches the air preheater outlet flue along its width. At least in the flue branch inlet of the dust collector with the highest temperature, a flue gas cooler, a first flue gas temperature measuring point, and a first flue gas flow measuring point are simultaneously installed. In the remaining flue branches inlet of the dust collector, flue gas resistance balancing dampers, second flue gas temperature measuring points, and second flue gas flow measuring points are simultaneously installed. By adjusting the opening of each flue gas resistance balancing damper and the liquid water flow rate in the flue gas cooler, balanced control of the inlet flue gas flow and temperature is achieved. This system avoids localized corrosion of the flue gas cooler due to low local flue gas temperature, as well as a series of problems such as low efficiency and poor reliability of the flue gas cooler caused by localized corrosion. It is simple and practical.

[0011] To address the blockage issue, the aforementioned system also includes an air preheater bypass flue, with its inlet connected to the air preheater inlet flue; the outlet of the air preheater bypass flue connects to the dust collector inlet branch flue equipped with a flue cooler, and the interface (the connection between the air preheater bypass flue outlet and the dust collector inlet branch flue) is located upstream of the flue cooler on the dust collector inlet branch flue, or the air preheater bypass flue outlet connects to the high-temperature side of the air preheater outlet flue (in the width direction of the air preheater outlet flue, one side has a higher temperature and the other side has a lower temperature; the side with the higher temperature is defined as the high-temperature side); a flue gas bypass regulating damper is installed on the air preheater bypass flue.

[0012] To meet the needs of general production and facilitate modification and control, as one preferred implementation scheme, the air preheater outlet flue is branched into two dust collector inlet branch flues along the width direction, namely a high-temperature flue and a low-temperature flue. That is, the dust collector inlet branch flue with a higher temperature is defined as the high-temperature flue, and the dust collector inlet branch flue with a lower temperature is defined as the low-temperature flue. A flue gas cooler, a first flue gas temperature measuring point, and a first flue gas flow measuring point are installed simultaneously in a high-temperature flue. The first flue gas temperature measuring point is located downstream of the flue gas cooler. A flue gas resistance balance regulating valve, a second flue gas temperature measuring point, and a second flue gas flow measuring point are simultaneously installed in a low-temperature flue. Adjust the opening of each flue gas resistance balancing valve based on the feedback values ​​from the first and second flue gas flow measurement points, so that the flow deviation in each dust collector inlet branch flue is less than 10% of the average flow. Adjust the flow rate of liquid water in the flue gas cooler based on the feedback values ​​of the first and second flue gas temperature measuring points, so that the flue gas temperature deviation in the inlet branch flue of each dust collector is less than 5℃.

[0013] To reduce or avoid blockage, when the system has a two-branch structure, it also includes an air preheater bypass flue. The air preheater bypass flue inlet connects to the air preheater inlet flue; the air preheater bypass flue outlet connects to the high-temperature flue, and the interface (the connection between the air preheater bypass flue outlet and the high-temperature flue) is located upstream of the flue gas cooler, or the air preheater bypass flue outlet connects to the high-temperature side of the air preheater outlet flue. A flue gas bypass regulating damper is installed on the air preheater bypass flue. While the opening of the flue gas bypass regulating damper is not conducive to energy saving, it significantly increases the flue gas cooler wall temperature, which helps prevent blockage in the flue gas cooler, and also increases the air preheater secondary air temperature, which helps prevent blockage in the air preheater.

[0014] The side with the higher temperature in the width direction of the air preheater outlet flue is defined as the high-temperature side. For ease of control, the branching points of the slightly higher temperature flue and the slightly lower temperature flue are located at 1 / 3 to 2 / 3 of the width of the air preheater outlet flue from the high-temperature side. More preferably, the branching points of the slightly higher temperature flue and the slightly lower temperature flue are located at 1 / 2 of the width of the air preheater outlet flue from the high-temperature side.

[0015] This application's dust collector inlet flue gas parameter leveling system, based on the combination of a flue gas cooler and a warm air heater, is applicable to various air preheaters. More preferably, it is applicable to rotary three-compartment air preheaters (air heaters).

[0016] To achieve energy recycling, a heater is installed in the air preheater's secondary air inlet duct; a circulating pump drives liquid water to absorb heat from the flue gas cooler and then release heat in the heater, forming a cycle.

[0017] To improve the accuracy and stability of the measurements, within the same dust collector inlet branch flue, the first flue gas flow measurement point is located downstream of the flue gas cooler, and the distance between the first flue gas temperature measurement point and the first flue gas flow measurement point and the flue gas cooler is not less than 20 cm. More preferably, the flue gas cooler, the first flue gas temperature measurement point, and the first flue gas flow measurement point are installed sequentially from upstream to downstream.

[0018] To improve the accuracy and stability of measurements and reduce the impact of the balancing damper's operation on flow and temperature measurements, within the same dust collector inlet branch flue, the second flue gas temperature measuring point and the second flue gas flow measuring point are both installed upstream of the balancing damper in the same dust collector inlet branch flue; the distance between the second flue gas temperature measuring point, the second flue gas flow measuring point, and the balancing damper is not less than 100 cm. More preferably, the second flue gas temperature measuring point, the second flue gas flow measuring point, and the balancing damper are installed sequentially from upstream to downstream.

[0019] To adapt to low-load operation of coal-fired units (referring to operation below rated load, where the flue gas volume is small and the overall flue gas temperature is low, which can easily cause ash accumulation in the flue or flue cooler), the above-mentioned flue gas resistance balance regulating valve can be completely closed during the low-load operation phase of the coal-fired unit, allowing all the flue gas to pass through the flue cooler, increasing the flue gas velocity, and alleviating the problem of ash accumulation in the flue or flue cooler.

[0020] Unless otherwise specified in this invention, all techniques are based on existing technologies.

[0021] This invention relates to a dust collector inlet flue gas parameter balancing system based on a combined flue gas cooler and air heater. It avoids or effectively alleviates the problem of localized corrosion of the flue gas cooler caused by low local flue gas temperature, and the resulting low efficiency and poor reliability of the flue gas cooler, thus improving the economic efficiency of the flue gas cooler operation. Simultaneously, it achieves balanced control of the flue gas flow rate and temperature at the dust collector inlet, avoiding or effectively alleviating the decrease in dust removal efficiency caused by uneven flue gas flow rate and temperature at the dust collector inlet, thereby improving dust removal efficiency and extending the service life of the dust collector. It is simple, practical, and easy to promote. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the dust collector inlet flue gas parameter leveling system based on the combination of a flue gas cooler and a heat exchanger, as described in this invention. Figure 1 .

[0023] Figure 2 yes Figure 1 AA view.

[0024] Figure 3 This is a schematic diagram of the structure of the dust collector inlet flue gas parameter leveling system based on the combination of a flue gas cooler and a heat exchanger, as described in this invention. Figure 2 .

[0025] Figure 4 yes Figure 3 AA view.

[0026] In the diagram, 1 is the air preheater, 2 is the dust collector, 3 is the high-temperature flue, 4 is the low-temperature flue, 5 is the cold secondary air duct, 6 is the cold secondary air heater, 7 is the flue gas cooler, 8 is the flue gas resistance balance regulating valve, 9 is the first flue gas temperature measuring point, 10 is the second flue gas temperature measuring point, 11 is the first flue gas flow measuring point, 12 is the second flue gas flow measuring point, 13 is the circulating pump, 14 is the air preheater inlet flue, 15 is the air preheater bypass flue, and 16 is the flue gas bypass regulating valve. Detailed Implementation

[0027] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0028] Example 1

[0029] like Figure 1-2 As shown, based on the dust collector inlet flue gas parameter leveling system that combines a flue gas cooler and a warm air heater, the air preheater outlet flue is branched into two or more dust collector inlet branch flues along the width direction. At least one flue gas cooler, a first flue gas temperature measuring point and a first flue gas flow measuring point shall be installed simultaneously in the inlet branch flue of the dust collector with the highest temperature. The first flue gas temperature measuring point in the same inlet branch flue of the dust collector shall be set downstream of the flue gas cooler. All other dust collector inlet branch flues are simultaneously equipped with flue gas resistance balancing regulating valves, second flue gas temperature measuring points, and second flue gas flow measuring points. Each dust collector inlet branch flue is connected to the dust collector inlet; Based on the feedback values ​​of the first and second flue gas flow measurement points, as well as the feedback values ​​of the first and second flue gas temperature measurement points, the opening degree of each flue gas resistance balancing valve and the flow rate of liquid water in the flue gas cooler are adjusted so that the flow deviation in each dust collector inlet branch flue is less than 10% of the average flow, and the flue gas temperature deviation in each dust collector inlet branch flue is less than 5℃.

[0030] The aforementioned dust collector inlet flue gas parameter balancing system, based on the combination of a flue gas cooler and a heater, branches the air preheater outlet flue along its width. At least in the flue branch inlet of the dust collector with the highest temperature, a flue gas cooler, a first flue gas temperature measuring point, and a first flue gas flow measuring point are simultaneously installed. In the remaining flue branches inlet of the dust collector, flue gas resistance balancing dampers, second flue gas temperature measuring points, and second flue gas flow measuring points are simultaneously installed. By adjusting the opening of each flue gas resistance balancing damper and the liquid water flow rate in the flue gas cooler, balanced control of the inlet flue gas flow and temperature is achieved. This system avoids localized corrosion of the flue gas cooler due to low local flue gas temperature, as well as a series of problems such as low efficiency and poor reliability of the flue gas cooler caused by localized corrosion. It is simple and practical.

[0031] Example 2

[0032] Unlike Example 1, as follows: Figure 2 As shown, in this example, the air preheater outlet flue is branched along its width into two dust collector inlet branch flues, namely a high-temperature flue and a low-temperature flue. A flue gas cooler, a first flue gas temperature measuring point, and a first flue gas flow measuring point are simultaneously installed in the high-temperature flue, with the first flue gas temperature measuring point located downstream of the cooler. A flue gas resistance balancing damper, a second flue gas temperature measuring point, and a second flue gas flow measuring point are simultaneously installed in the low-temperature flue. The opening of each flue gas resistance balancing damper is adjusted based on the feedback values ​​from the first and second flue gas flow measuring points, ensuring that the flow deviation in each dust collector inlet branch flue is less than 10% of the average flow. The flow rate of liquid water in the cooler is adjusted based on the feedback values ​​from the first and second flue gas temperature measuring points, ensuring that the flue gas temperature deviation in each dust collector inlet branch flue is less than 5°C.

[0033] Example 3

[0034] Based on Example 2, the following improvements were made: the side with higher temperature in the width direction of the air preheater outlet flue was defined as the high-temperature side. For ease of control, the branch positions of the high-temperature flue and the low-temperature flue were located at 1 / 2 of the width of the air preheater outlet flue from the high-temperature side.

[0035] Example 4

[0036] Based on Example 3, the following improvements were made: A rotary three-compartment structure was adopted in this example. A heater was installed in the air preheater's cold secondary air inlet duct; liquid water was driven by a circulating pump to absorb heat from the flue gas cooler and then release heat in the heater, forming a circulation.

[0037] Example 5

[0038] Based on Example 4, the following improvements were made: To improve the accuracy and stability of the measurements, the flue gas cooler, the first flue gas temperature measuring point, and the first flue gas flow measuring point in the high-temperature flue were installed sequentially from upstream to downstream. The distance between the first flue gas temperature measuring point and the flue gas cooler was 30cm (experimentally, it could also be 40cm, 50cm, etc.), and the distance between the first flue gas temperature measuring point and the first flue gas flow measuring point was 15cm (experimentally, it could also be 5cm, 20cm, etc.). In the low-temperature flue, the second flue gas temperature measuring point, the second flue gas flow measuring point, and the balance regulating valve were installed sequentially from upstream to downstream. The distance between the second flue gas temperature measuring point and the balance regulating valve was 120cm (experimentally, it could also be 150cm, 160cm, etc.), and the distance between the second flue gas temperature measuring point and the second flue gas flow measuring point was 40cm (experimentally, it could also be 30cm, 60cm, etc.).

[0039] Example 6

[0040] Based on Example 5, the following improvements were further made: Figure 3-4 As shown, the dust collector inlet flue gas parameter leveling system based on the combined flue gas cooler and air heater also includes an air preheater bypass flue. The air preheater bypass flue inlet is connected to the air preheater inlet flue; the air preheater bypass flue outlet is connected to a slightly higher temperature flue, and the interface (the connection between the air preheater bypass flue outlet and the slightly higher temperature flue) is located upstream of the flue gas cooler, or the air preheater bypass flue outlet is connected to the high-temperature side of the air preheater outlet flue. A flue gas bypass regulating damper is installed on the air preheater bypass flue. When the flue gas cooler or air preheater becomes blocked, the flue gas bypass regulating damper is opened; after the blockage is resolved or alleviated, the flue gas bypass regulating damper is closed.

[0041] When the coal-fired unit is operating at low load, the flue gas resistance balance regulating valve can be completely closed to allow all the flue gas to pass through the flue gas cooler, thereby increasing the flue gas flow rate and alleviating the problem of ash accumulation in the flue or flue gas cooler.

[0042] The above examples, based on a dust collector inlet flue gas parameter balancing system combining a flue gas cooler and a warm air heater, avoid or effectively alleviate the problem of localized corrosion of the flue gas cooler caused by low local flue gas temperature, as well as a series of problems such as low efficiency and poor reliability of the flue gas cooler caused by localized corrosion, thus improving the economic benefits of flue gas cooler operation. At the same time, it achieves balanced control of flue gas flow and temperature at the dust collector inlet, avoiding or effectively alleviating the decrease in dust removal efficiency caused by uneven flue gas flow and temperature at the dust collector inlet, thereby improving dust removal efficiency and extending the service life of the dust collector. It is simple, practical, and easy to promote.

Claims

1. A dust collector inlet flue gas parameter leveling system based on a combination of a flue gas cooler and a warm air heater, characterized in that: The air preheater outlet flue is branched into two or more dust collector inlet branch flues along the width direction; At least one flue gas cooler, a first flue gas temperature measuring point and a first flue gas flow measuring point shall be installed simultaneously in the inlet branch flue of the dust collector with the highest temperature. The first flue gas temperature measuring point in the same inlet branch flue of the dust collector shall be set downstream of the flue gas cooler. All other dust collector inlet branch flues are simultaneously equipped with flue gas resistance balancing regulating valves, second flue gas temperature measuring points, and second flue gas flow measuring points. Each dust collector inlet branch flue is connected to the dust collector inlet; Based on the feedback values ​​of the first flue gas flow measurement point and the second flue gas flow measurement point, as well as the feedback values ​​of the first flue gas temperature measurement point and the second flue gas temperature measurement point, the opening of each flue gas resistance balance valve and the liquid water flow rate in the flue cooler are adjusted so that the flow deviation in each dust collector inlet branch flue is less than 10% of the average flow, and the flue gas temperature deviation in each dust collector inlet branch flue is less than 5℃. It also includes the air preheater bypass flue, the air preheater bypass flue inlet is connected to the air preheater inlet flue; The outlet of the air preheater bypass flue is connected to the inlet branch flue of the dust collector equipped with a flue cooler, and the interface is located upstream of the flue cooler on the inlet branch flue of the dust collector, or the outlet of the air preheater bypass flue is connected to the high-temperature side of the air preheater outlet flue; a flue gas bypass regulating damper is installed on the air preheater bypass flue.

2. The dust collector inlet flue gas parameter leveling system based on the combination of a flue gas cooler and a warm air heater as described in claim 1, characterized in that: The air preheater outlet flue is branched into two dust collector inlet branch flues along the width direction, namely a high-temperature flue and a low-temperature flue. A flue gas cooler, a first flue gas temperature measuring point, and a first flue gas flow measuring point are installed simultaneously in a high-temperature flue. The first flue gas temperature measuring point is located downstream of the flue gas cooler. A flue gas resistance balance regulating valve, a second flue gas temperature measuring point, and a second flue gas flow measuring point are simultaneously installed in a low-temperature flue. Adjust the opening of each flue gas resistance balancing valve based on the feedback values ​​of the first and second flue gas flow measurement points, so that the flow deviation in each dust collector inlet branch flue is less than 10% of the average flow. Adjust the flow rate of liquid water in the flue gas cooler based on the feedback values ​​of the first and second flue gas temperature measuring points, so that the flue gas temperature deviation in the inlet branch flue of each dust collector is less than 5℃.

3. The dust collector inlet flue gas parameter leveling system based on the combination of a flue gas cooler and a warm air heater as described in claim 2, characterized in that: The side with higher temperature in the width direction of the air preheater outlet flue is defined as the high-temperature side. The branch positions of the slightly high-temperature flue and the slightly low-temperature flue are located at 1 / 3 to 2 / 3 of the width of the air preheater outlet flue from the high-temperature side.

4. The dust collector inlet flue gas parameter leveling system based on the combination of a flue gas cooler and a warm air heater as described in claim 3, characterized in that: The branching points of the high-temperature flue and the low-temperature flue are located at 1 / 2 of the width of the air preheater outlet flue from the high-temperature side.

5. The dust collector inlet flue gas parameter leveling system based on the combination of a flue gas cooler and a warm air heater according to any one of claims 1-4, characterized in that: The air preheater is a rotary three-compartment structure.

6. The dust collector inlet flue gas parameter leveling system based on the combination of a flue gas cooler and a warm air heater as described in claim 5, characterized in that: A heater is installed in the air inlet duct of the air preheater for cold secondary air; liquid water is driven by a circulating pump to absorb heat from the flue gas cooler and then release heat in the heater, forming a cycle.

7. The dust collector inlet flue gas parameter leveling system based on the combination of a flue gas cooler and a warm air heater according to any one of claims 1-4, characterized in that: Within the same dust collector inlet branch flue, the first flue gas flow measurement point is located downstream of the flue gas cooler, and the distance between the first flue gas temperature measurement point and the first flue gas flow measurement point and the flue gas cooler is not less than 20cm.

8. The dust collector inlet flue gas parameter leveling system based on the combination of a flue gas cooler and a warm air heater according to any one of claims 1-4, characterized in that: Within the same dust collector inlet branch flue, the second flue gas temperature measuring point and the second flue gas flow measuring point are both installed upstream of the balance regulating valve in the inlet branch flue of the dust collector; the distance between the second flue gas temperature measuring point, the second flue gas flow measuring point and the balance regulating valve is not less than 100cm.

9. The dust collector inlet flue gas parameter leveling system based on the combination of a flue gas cooler and a warm air heater according to any one of claims 1-4, characterized in that: During the low-load operation phase of a coal-fired unit, the flue gas resistance balance regulating valve is completely closed, allowing all the flue gas to pass through the flue gas cooler, thereby increasing the flue gas flow rate and alleviating the problem of ash accumulation in the flue or flue gas cooler.

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