A device and control method for improving the dynamic adjustment range of the wall temperature of a rotary air preheater

Abstract

This invention discloses a device and control method for improving the dynamic adjustment range of the wall temperature of a rotary air preheater by dividing the rings into N rings. N ring-shaped air inlet pipes, corresponding to the N rings, are installed at the cold end of at least one cold medium compartment. Each ring-shaped air inlet pipe is equipped with a ring-shaped regulating valve. The invention also includes ring-shaped cold air ducts and ring-shaped cold air duct regulating valves, with N ring-shaped cold air ducts and regulating valves. The ring-shaped cold air ducts, regulating valves, and air ring inlet pipes are in one-to-one correspondence. The ring-shaped cold air duct regulating valves are installed on the corresponding ring-shaped cold air ducts. The upstream end of the ring-shaped cold air duct flows into the corresponding ring-shaped air inlet pipe from the downstream end of the corresponding ring-shaped cold air duct regulating valve, and the downstream end flows into the flue gas compartment outlet. This invention not only ensures the range of ring-shaped temperature rise, thus better ensuring the anti-clogging effect, but also reduces or avoids the impact of high flue gas temperature in a certain ring on downstream dust removal equipment.

Description

Technical Field

[0001] This invention relates to a device and control method for improving the dynamic adjustment range of the wall temperature of a rotary air preheater, belonging to the technical field of anti-clogging technology for rotary air preheaters in coal-fired power plants. Background Technology

[0002] Rotary air preheaters used in coal-fired power generation are generally three- or four-compartment structures, including an air compartment (containing primary and secondary air compartments) and a flue gas compartment. They utilize the heat from high-temperature flue gas to heat the air, thereby achieving energy recovery and utilization. However, as the flue gas temperature decreases, SO3 in the flue gas reacts with NH3 escaping from upstream denitrification to form ammonium bisulfate (NH4HSO4), which is liquid in the range of 146–207°C. This liquid, along with fly ash from coal combustion, adheres to the surface of the heat storage elements, causing ash blockage in the air preheater. When the temperature decreases further, SO3 also reacts with water vapor in the flue gas to form liquid sulfuric acid (H2SO4), resulting in low-temperature corrosion, further exacerbating the blockage and corrosion problems of the air preheater's heat storage elements.

[0003] Chinese patent 202122061569.7 discloses a rotary air preheater anti-clogging system based on ring-based circulating heating. The air preheater rotor is divided into multiple concentric rings, and the cold air volume of each ring can be independently adjusted via ring-based regulating valves. When the cold air volume of a particular ring is reduced, the flue gas temperature on the corresponding ring's flue gas side rises, and the wall temperature of the heat storage element in that ring increases. This effectively performs ring-based dynamic temperature adjustment of the air preheater wall, with each ring periodically vaporizing to form acidic liquid that blocks ash, periodically loosening the accumulated ash. However, in practical use, due to the existence of dynamic and static sealing gaps and the difficulty in achieving zero leakage when the ring-based regulating valves are closed, if the installation process is not up to standard, a small amount of cold air may still flow through the heat storage element of the corresponding ring even when the regulating valve of the heating ring is completely closed. The upper limit of the ring-based heating of the air preheater rotor may not reach 207°C, thus affecting the vaporization rate of ammonium bisulfate and the anti-clogging effect of the air preheater. Furthermore, during the dynamic adjustment of the air preheater wall temperature in different rings, the high exhaust temperature in one ring at the air preheater flue gas outlet prevents sufficient mixing with the lower-temperature exhaust gases from other rings. This can adversely affect downstream dust removal equipment, especially when a bag filter is directly installed downstream of the air preheater flue gas side. The target temperature for the air preheater rings is above 200℃, meaning there are localized areas at the air preheater flue gas outlet exceeding 200℃. However, the maximum allowable temperature for bag filters is generally no more than 170℃. Exceeding this temperature will cause the filter bags to erode and significantly reduce dust removal efficiency. Summary of the Invention

[0004] In order to broaden the adjustment range of the wall temperature split loop in the existing technology and solve the problem of local overheating during the adjustment of the wall temperature split loop, the present invention provides a device and control method for improving the dynamic adjustment range of the wall temperature split loop in the rotary air preheater.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A device for improving the dynamic adjustment range of the wall temperature of a rotary air preheater is disclosed. The cold end face of the air preheater rotor is divided into N rings, where N≥2. N ring inlet pipes corresponding to the N rings are set at the cold end of at least one cold medium compartment. Each ring inlet pipe is matched and connected to the bottom of each ring. Each ring inlet pipe is equipped with a ring regulating valve. The cold air volume of each ring inlet pipe is independently controlled by the corresponding ring regulating valve. The device also includes ring cold air ducts and ring duct regulating valves. There are N ring cold air ducts and ring duct regulating valves. The ring cold air ducts, ring duct regulating valves, and air ring inlet pipes are in one-to-one correspondence. The ring duct regulating valves are installed on the corresponding ring cold air ducts. One end of the ring cold air duct is the upstream end and the other end is the downstream end. The upstream end of the ring cold air duct enters the corresponding ring inlet pipe from the downstream end of the corresponding ring duct regulating valve, and the downstream end enters the flue gas compartment outlet.

[0007] The upstream to downstream direction of this application is consistent with the direction of airflow.

[0008] The above N rings correspond one-to-one with the N sub-ring air inlet pipes.

[0009] As is common knowledge, a rotary air preheater includes a cooling medium compartment (air compartment) and a flue gas compartment. Generally, the lower end of the cooling medium compartment is the inlet and the upper end is the outlet, while the upper end of the flue gas compartment is the inlet and the lower end is the outlet.

[0010] This application, while setting up separate rings and separate ring inlet ducts and separate ring regulating dampers, also sets up separate ring cold air ducts and separate ring duct regulating dampers. This not only ensures the range of temperature rise of the separate rings, thereby ensuring the anti-clogging effect, but also reduces or avoids the impact of high exhaust temperature of a certain ring on downstream dust removal and other equipment.

[0011] To facilitate control of the adjustment range of the regulating gate of the sub-loop cooling duct, each of the above-mentioned sub-loop cooling air ducts is equipped with a sub-loop cooling air temperature measuring point.

[0012] To minimize the risk of overheating in downstream equipment of the air preheater, preferably, the downstream end of the aforementioned ring-type cold air venting duct is located in the same ring as the upstream end, that is, the downstream end of the ring-type cold air venting duct is located below the heat storage element, which is located in the same ring as its upstream end (the upstream end of the ring-type cold air venting duct).

[0013] The downstream end and upstream end of the aforementioned ring-type cold air venting duct are located in the same ring, meaning that the downstream end and upstream end of the ring-type cold air venting duct are located within the vertical projection of the same ring on the cold end face of the air preheater rotor.

[0014] To further improve the mixing effect of cold air and flue gas, an annular cold air distribution device is provided at the downstream end of the split-ring cold air duct.

[0015] One specific implementation scheme includes an annular cold air distribution device comprising at least one arc-shaped pipe (arc-shaped along its length). All arc-shaped pipes are connected to the downstream end of the ring-shaped cold air duct. The arc-shaped pipes have downward-facing air outlets. Cold air from the ring-shaped cold air duct flows out through the air outlets and mixes with the flue gas. The aforementioned "downward-facing air outlets on the arc-shaped pipes" means that the air outlets are located on the lower side (backflow side) of the arc-shaped pipes, which effectively prevents or reduces dust accumulation and blockage.

[0016] As one specific implementation scheme, the above-mentioned ring-shaped air inlet pipe includes a fan-shaped cross-section segment, a transition segment and a rectangular cross-section segment connected sequentially from top to bottom, and the ring-shaped regulating door is located on the rectangular cross-section segment; the upper end face of the ring-shaped air inlet pipe is a fan-shaped air outlet and the lower end face is a rectangular air inlet, and the two arc-shaped sides of the fan-shaped air outlet are vertically opposite to the two arc-shaped sides of the corresponding ring.

[0017] The cross-section of the aforementioned sector-shaped section is sector-shaped; the cross-section of the transition section is a transition shape from sector to rectangle; and the cross-section of the rectangular section is rectangular.

[0018] The term "fan" in this application refers to a shape formed by two arcs with the same curvature and two radial sides connecting the two ends of the arcs.

[0019] A control method for improving the dynamic adjustment range of the wall temperature of a rotary air preheater by loop adjustment involves first gradually closing the opening of the loop adjustment valve on the inlet duct of a certain loop while keeping the corresponding loop venting valve completely closed. The closing speed of the loop adjustment valve is based on the assumption that the temperature rise of the corresponding loop exhaust gas temperature or the wall temperature of the heat storage element does not exceed 2℃ / min. If, during the closing process of the loop adjustment valve, overheating of downstream equipment of the air preheater is detected, or if the corresponding loop heat storage element still needs further heating after the loop adjustment valve is completely closed, then the loop venting valve adjustment valve is gradually opened. The opening degree of the valve and the opening speed of the regulating valve of the sub-ring venting pipe are based on the fact that the temperature rise of the corresponding ring flue gas temperature or the wall temperature of the heat storage element does not exceed 2℃ / min. After the corresponding ring heat storage element has completed the temperature rise and clearing, the regulating valve of the corresponding ring sub-ring venting pipe is first gradually closed, and then the regulating valve of the corresponding ring sub-ring is gradually opened. The closing speed of the regulating valve of the sub-ring venting pipe and the opening speed of the regulating valve of the sub-ring are both based on the fact that the temperature drop of the corresponding ring flue gas temperature or the wall temperature of the heat storage element does not exceed 2℃ / min. The clearing and adjustment of each ring is completed in turn according to the above steps.

[0020] The "gradual" speeds mentioned in each step of this application are based on the premise that the change in the corresponding flue gas temperature or the wall temperature of the heat storage element does not exceed 2℃ / min. If it is a heating process, the heating rate should not exceed 2℃ / min; if it is after unblocking, the cooling rate should not exceed 2℃ / min. That is to say, the heating and cooling ranges should not be too large in each adjustment process, otherwise it may cause abnormal deformation of the air preheater rotor, which may lead to the air preheater seizing up.

[0021] Perform regular rotation operations on each ring following the steps described above.

[0022] To minimize heat loss during the dynamic adjustment of the air preheater wall temperature in each loop, preferably, each loop cooling air duct is equipped with a loop cooling air temperature measuring point. If the cooling air temperature measured by the loop cooling air temperature measuring point rises as the loop cooling air regulating gate gradually opens, the corresponding loop cooling air regulating gate will not be opened further, but will remain unchanged.

[0023] In order to ensure the anti-blocking effect while reducing or avoiding the impact of flue gas temperature rise on downstream equipment, the cold air in the sub-ring air inlet pipe is guided to the flue gas compartment outlet located in the same ring as the sub-ring air inlet pipe through the sub-ring cold air duct.

[0024] To improve the mixing effect of cold air and flue gas, an annular cold air distribution device at the downstream end of the ring-shaped cold air distribution duct ensures that the distributed cold air is fully mixed with the local high-temperature flue gas in the corresponding ring.

[0025] Any techniques not mentioned in this invention are based on existing technologies.

[0026] This invention relates to a device for improving the dynamic adjustment range of the wall temperature of a rotary air preheater by ring. In addition to the ring and the setting of the ring inlet pipe and the ring regulating valve, a ring cold air venting pipe and a ring venting pipe regulating valve are also set. This not only ensures the range of ring temperature increase, thus better ensuring the anti-clogging effect, but also reduces or avoids the impact of high exhaust temperature of a certain ring on downstream dust removal and other equipment. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the device for dynamically adjusting the wall temperature of the rotary air preheater in Embodiment 1 of the present invention.

[0028] Figure 2 This is a top view of the cold end of the rotary air preheater in Embodiment 1 of the present invention;

[0029] Figure 3 This is a schematic diagram of the device for increasing the dynamic adjustment range of the rotary air preheater wall temperature distribution ring in Embodiment 4 of the present invention;

[0030] Figure 4This is a top view of the cold end of the rotary air preheater in Embodiment 4 of the present invention;

[0031] In the diagram, 1 is the ring-shaped air inlet pipe, 2 is the ring-shaped regulating valve, 3 is the ring-shaped cold air duct, 4 is the ring-shaped cold air duct regulating valve, 5 is the ring-shaped cold air temperature measuring point, 6 is the ring-shaped cold air distribution device, 7 is the circumferential baffle, and 8 is the air preheater rotor. The arrows in the diagram indicate the airflow direction. Detailed Implementation

[0032] 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.

[0033] Examples 1 and 2 are two instances in which the cold end face of the air preheater rotor is divided into 2 rings and 3 rings, respectively; Examples 3-6 are further improvements based on Examples 1 and 2, and each of Examples 3 / 4 / 5 / 6 includes two instances of 2 rings and 3 rings.

[0034] Example 1

[0035] like Figure 1-2 As shown, a device for dynamically adjusting the wall temperature of a rotary air preheater (a three-compartment structure including a primary air compartment, a secondary air compartment, and a flue gas compartment) is disclosed. The cold end face of the air preheater rotor is divided into two concentric rings of equal area by a circumferential partition. Two sub-ring air inlet pipes corresponding to the two concentric rings are installed at the cold end of the secondary air compartment. Each sub-ring air inlet pipe is connected to the lower part of its respective ring. Each sub-ring air inlet pipe is equipped with a sub-ring regulating damper, and the cold air volume of each sub-ring air inlet pipe is independently controlled through the corresponding sub-ring regulating damper. The system also includes two separate ring cold air ducts and two separate ring cold air duct regulating valves. The separate ring cold air ducts, the separate ring cold air duct regulating valves, and the air ring inlet pipes correspond one-to-one. The separate ring cold air duct regulating valves are installed on the corresponding separate ring cold air ducts. One end of the separate ring cold air duct is the upstream end, and the other end is the downstream end. The upstream end of the separate ring cold air duct enters the corresponding separate ring inlet pipe from the downstream end of the corresponding separate ring cold air duct regulating valve, and the downstream end enters the flue gas compartment outlet.

[0036] The control method using the above-mentioned device involves first gradually closing the opening of the regulating damper on a specific loop inlet duct while keeping the corresponding loop venting damper completely closed. The closing speed of the loop regulating damper is based on the assumption that the temperature rise of the corresponding loop exhaust gas temperature or the wall temperature of the heat storage element does not exceed 2°C / min. If, during the closing process of the loop regulating damper, overheating of the downstream equipment of the air preheater is detected, or if the corresponding loop heat storage element still requires further heating after the loop regulating damper is completely closed, then the opening of the loop venting damper is gradually opened. The opening speed of the loop venting damper is based on the... The temperature rise of the corresponding ring's exhaust gas temperature or the wall temperature of the heat storage element should not exceed 2℃ / min. After the corresponding ring's heat storage element has completed its temperature rise and clearing process, first gradually close the corresponding ring's sub-ring venting valve, ensuring the closing speed of the sub-ring venting valve is such that the temperature drop of the corresponding ring's exhaust gas temperature or the wall temperature of the heat storage element does not exceed 2℃ / min. Then gradually open the corresponding ring's sub-ring venting valve, ensuring the opening speed of the sub-ring venting valve is such that the temperature drop of the corresponding ring's exhaust gas temperature or the wall temperature of the heat storage element does not exceed 2℃ / min. Repeat the aforementioned steps to complete the clearing and adjustment of each ring. Perform the aforementioned steps periodically for each ring.

[0037] The aforementioned device, while separating the rings and setting up the ring inlet pipes and ring regulating valves, also sets up ring cold air ducts and ring duct regulating valves. This not only ensures the range of ring temperature rise, thereby ensuring the anti-clogging effect, but also reduces or avoids the impact of high exhaust temperature in a certain ring on downstream dust removal and other equipment.

[0038] Example 2

[0039] like Figure 3-4 As shown, a device for dynamically adjusting the wall temperature of a rotary air preheater (a three-compartment structure including a primary air compartment, a secondary air compartment, and a flue gas compartment) is disclosed. The cold end face of the air preheater rotor is divided into three concentric rings of equal area by a circumferential partition. Three sub-ring air inlet pipes corresponding to the three concentric rings are installed at the cold end of the secondary air compartment. Each sub-ring air inlet pipe is connected to the lower part of its respective ring. Each sub-ring air inlet pipe is equipped with a sub-ring regulating damper, and the cold air volume of each sub-ring air inlet pipe is independently controlled through the corresponding sub-ring regulating damper. The system also includes three separate ring cold air ducts and three separate ring cold air duct regulating valves. The three separate ring cold air ducts, the separate ring cold air duct regulating valves, and the air ring inlet pipes correspond one-to-one. The separate ring cold air duct regulating valves are installed on the corresponding separate ring cold air ducts. One end of the separate ring cold air duct is the upstream end and the other end is the downstream end. The upstream end of the separate ring cold air duct enters the corresponding separate ring inlet pipe from the downstream end of the corresponding separate ring cold air duct regulating valve, and the downstream end enters the flue gas compartment outlet.

[0040] The control method using the above-mentioned device involves first gradually closing the opening of the regulating damper on a specific loop inlet duct while keeping the corresponding loop venting damper completely closed. The closing speed of the loop regulating damper is based on the assumption that the temperature rise of the corresponding loop exhaust gas temperature or the wall temperature of the heat storage element does not exceed 2°C / min. If, during the closing process of the loop regulating damper, overheating of the downstream equipment of the air preheater is detected, or if the corresponding loop heat storage element still requires further heating after the loop regulating damper is completely closed, then the opening of the loop venting damper is gradually opened. The opening speed of the loop venting damper is based on the... The temperature rise of the corresponding ring's exhaust gas temperature or the wall temperature of the heat storage element should not exceed 2℃ / min. After the corresponding ring's heat storage element has completed its temperature rise and clearing process, first gradually close the corresponding ring's sub-ring venting valve, ensuring the closing speed of the sub-ring venting valve is such that the temperature drop of the corresponding ring's exhaust gas temperature or the wall temperature of the heat storage element does not exceed 2℃ / min. Then gradually open the corresponding ring's sub-ring venting valve, ensuring the opening speed of the sub-ring venting valve is such that the temperature drop of the corresponding ring's exhaust gas temperature or the wall temperature of the heat storage element does not exceed 2℃ / min. Repeat the aforementioned steps to complete the clearing and adjustment of each ring. Perform the aforementioned steps periodically for each ring.

[0041] The aforementioned device, while separating the rings and setting up the ring inlet pipes and ring regulating valves, also sets up ring cold air ducts and ring duct regulating valves. This not only ensures the range of ring temperature rise, thereby ensuring the anti-clogging effect, but also reduces or avoids the impact of high exhaust temperature in a certain ring on downstream dust removal and other equipment.

[0042] Example 3

[0043] Based on Examples 1 and 2, the following improvements were further made: Figure 1 and Figure 3 As shown, in order to minimize heat loss during the dynamic adjustment of the air preheater wall temperature in each loop, each of the above-mentioned loop cold air venting pipes is equipped with a loop venting cold air temperature measuring point. When the loop venting regulating gate is gradually opened, if the venting cold air temperature measured by the loop venting cold air temperature measuring point rises, the corresponding loop venting regulating gate will no longer be opened further, but the opening degree of the corresponding loop venting regulating gate will remain unchanged.

[0044] Example 4

[0045] Based on Example 3, the following improvements were made: Figure 1 and Figure 3 As shown, to minimize the risk of overheating in downstream equipment of the air preheater, the downstream end of the ring-type cold air venting duct leads to the flue gas compartment outlet, and its upstream end (the upstream end of the ring-type cold air venting duct) is located below the heat storage element in the same ring. In other words, the upstream and downstream ends of the ring-type cold air venting duct are located in the same ring, thus guiding the cold air from the ring-type inlet duct to the flue gas compartment outlet, and below the heat storage element located in the same ring as the ring-type inlet duct.

[0046] Example 5

[0047] Based on Example 4, the following improvements were further made: Figure 2 and Figure 4 As shown, to improve the mixing effect of cold air and flue gas, an annular cold air distribution device is provided at the downstream end of the ring-shaped cold air duct, so that the vented cold air is fully mixed with the local high-temperature flue gas of the corresponding ring. In this example, the annular cold air distribution device includes an arc-shaped pipe, which is parallel to the adjacent circumferential baffle. The downstream end of the ring-shaped cold air duct is connected to the arc-shaped pipe. Downward-opening air outlets are distributed along the length of the arc-shaped pipe, with a diameter of 2.5 cm and a spacing of 5 cm. Of course, depending on the actual working conditions, two or more arc-shaped pipes can be installed, with spacing and diameters that meet the uniformity requirements. The cold air in the ring-shaped cold air duct flows out from the air outlets and mixes with the flue gas.

[0048] Example 6

[0049] Based on Example 5, the following improvements were made: the ring-shaped air inlet pipe includes a fan-shaped cross-section, a transition section and a rectangular cross-section connected sequentially from top to bottom, and the ring-shaped regulating door is located on the rectangular cross-section; the upper end face of the ring-shaped air inlet pipe is a fan-shaped air outlet and the lower end face is a rectangular air inlet, and the two arc-shaped sides of the fan-shaped air outlet are vertically opposite to the two arc-shaped sides of the corresponding ring.

[0050] The devices described above for dynamically adjusting the wall temperature of rotary air preheaters by ring are equipped with ring-type cold air ducts and regulating valves, as well as ring-type cold air ducts and regulating valves. Practical verification, after 18 months of continuous operation, not only ensures the ring-type temperature rise (all can rise to over 210℃), thus better ensuring the anti-clogging effect, but also prevents downstream dust removal equipment from being affected by high exhaust temperatures in any ring (dust collector inlet temperature rise never exceeds 20℃, and temperature never exceeds 160℃). Furthermore, the operation is stable and safe, without any air preheater jamming or other problems.

Claims

1. A device for improving the dynamic adjustment range of the wall temperature of a rotary air preheater, wherein the cold end face of the air preheater rotor is divided into N rings, N≥2, and N ring inlet pipes (1) corresponding to the N rings are provided at the cold end of at least one cold medium compartment, each ring inlet pipe (1) is matched and connected to the bottom of each ring, and each ring inlet pipe (1) is provided with a ring regulating valve (2), and the cold air volume of each ring inlet pipe (1) is independently controlled by the corresponding ring regulating valve (2), characterized in that: It also includes a ring-type cold air duct (3) and a ring-type cold air duct regulating valve (4). The number of ring-type cold air ducts (3) and ring-type cold air duct regulating valves (4) is N. The ring-type cold air ducts (3), ring-type cold air duct regulating valves (4) and ring-type air inlet pipes (1) correspond one-to-one. The ring-type cold air duct regulating valves (4) are installed on the corresponding ring-type cold air ducts (3). One end of the ring-type cold air duct (3) is the upstream end and the other end is the downstream end. The upstream end of the ring-type cold air duct (3) is connected to the corresponding ring-type air inlet pipe (1) from the downstream of the corresponding ring-type cold air duct regulating valve (4), and the downstream end is connected to the flue gas compartment outlet. The downstream end of the ring-shaped cold air duct (3) is provided with a ring-shaped cold air distribution device (6). The annular cold air distribution device (6) includes at least one arc-shaped pipe. All the arc-shaped pipes are connected to the downstream end of the ring-shaped cold air distribution pipe. The arc-shaped pipes are distributed with downward-facing air outlets. The ring-shaped air inlet pipe (1) includes a fan-shaped section, a transition section and a rectangular section connected from top to bottom. The ring-shaped regulating door (2) is located on the rectangular section. The upper end face of the ring-shaped air inlet pipe (1) is a fan-shaped air outlet and the lower end face is a rectangular air inlet. The two arc-shaped sides of the fan-shaped air outlet are vertically opposite to the two arc-shaped sides of the corresponding ring.

2. The device for dynamically adjusting the wall temperature of a rotary air preheater as described in claim 1, characterized in that: Each ring-type cold air duct (3) is equipped with a ring-type cold air temperature measuring point (5).

3. The device for dynamically adjusting the wall temperature of a rotary air preheater as described in claim 1 or 2, characterized in that: The downstream end and the upstream end of the ring-type cold air venting duct (3) are located in the same ring.

4. A control method for increasing the dynamic adjustment amplitude of the rotary air preheater wall temperature through a separate loop, comprising using the device for increasing the dynamic adjustment amplitude of the rotary air preheater wall temperature through a separate loop as described in any one of claims 1-3, characterized in that: First, gradually reduce the opening of the ring regulating valve (2) on a certain ring inlet pipe (1) while keeping the corresponding ring venting regulating valve (4) completely closed. The closing speed of the ring regulating valve (2) is based on the fact that the temperature rise of the corresponding ring exhaust gas temperature or the wall temperature of the heat storage element does not exceed 2℃ / min. When it is detected that the downstream equipment of the air preheater is operating at an overheating rate or the corresponding ring heat storage element still needs to be further heated after the ring regulating valve (2) is completely closed, then gradually open the opening of the ring venting regulating valve (4) to ventilate the ring. The opening speed of the pipe regulating valve (4) is based on the fact that the corresponding ring exhaust temperature or the wall temperature of the heat storage element does not exceed 2℃ / min. After the corresponding ring heat storage element has completed the temperature rise and blockage clearing, the corresponding ring sub-ring dredging pipe regulating valve (4) is closed first, and then the corresponding ring sub-ring regulating valve (2) is opened gradually. The closing speed of the sub-ring dredging pipe regulating valve (4) and the opening speed of the sub-ring regulating valve (2) are both based on the fact that the corresponding ring exhaust temperature or the wall temperature of the heat storage element does not exceed 2℃ / min. The blockage clearing and regulation of each ring is completed in turn according to the above steps.

5. The control method for increasing the dynamic adjustment amplitude of the wall temperature of a rotary air preheater as described in claim 4, characterized in that: If the temperature of the cold air measured at the temperature measuring point (5) of the cold air in the ring dredging duct rises during the gradual opening of the regulating gate, the corresponding regulating gate of the ring dredging duct will no longer be opened further, but the opening degree of the corresponding regulating gate of the ring dredging duct will remain unchanged.

6. The control method for the dynamic adjustment amplitude of the wall temperature of a rotary air preheater as described in claim 4 or 5, characterized in that: The cold air in the ring-shaped air inlet pipe (1) is guided to the flue gas compartment outlet located in the same ring as the ring-shaped air inlet pipe (1) through the ring-shaped cold air duct (3).

7. The control method for dynamically adjusting the wall temperature of a rotary air preheater as described in claim 6, characterized in that: The annular cold air distribution device (6) at the downstream end of the ring-shaped cold air duct (3) ensures that the vented cold air is fully mixed with the local high-temperature flue gas of the corresponding ring.

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