A hot end radial sealing device that adapts to thermal deformation of air preheater rotor

Abstract

The present invention discloses a hot end radial sealing device that is adaptive to the thermal deformation of the air preheater rotor. The device adopts two clamping plate sealing sheets fixed on the upper end of the radial partition plate, separated by a gasket in the middle, and a dynamic sealing sheet is arranged above the gasket between the two clamping plate sealing sheets. The inner end of the dynamic sealing sheet is connected to the clamping plate sealing sheet by a pin, and the outer end is connected to the compensator. When the air preheater is working in a hot state, the compensator provides a compensation amount that matches the rotor deformation amount well, so that the dynamic sealing sheet is close to the fan-shaped plate sealing surface and maintains a certain safety gap, thereby eliminating the hot end triangular air leakage area formed by the rotor deformation. The present invention divides the sealing sheet into a fixed part and a movable part with the rotor. During operation, the hot end fan-shaped plate does not need to be adjusted up and down, and the dynamic sealing sheet can always avoid contacting the fan-shaped plate, which greatly reduces the air leakage rate of the air preheater. The device has the advantages of simple structure, no operation wear, low investment, fast construction, less maintenance, and high reliability.

Description

Technical Field

[0001] The invention relates to a hot end radial sealing device for adaptively adapting to thermal deformation of an air preheater rotor, belonging to the field of rotary air preheaters in thermal power plant equipment. Background Art

[0002] The air preheater is an important component of the boiler system of a thermal power plant. It is used to absorb the waste heat of flue gas below 400°C in the boiler, which can improve the overall efficiency of the boiler by 12-15%. Large thermal power units are mostly equipped with compact large-diameter rotary air preheaters. When the equipment is running, the temperature of the hot end of the rotor (usually at the upper end) can be 200-300°C higher than that of the cold end (usually at the lower end), causing the air preheater rotor to change from a cold cylindrical shape to a mushroom shape with drooping outer peripheries at the upper and lower ends. The gap between the outer periphery of the hot end of the rotor and the hot end fan plate fixed on the sealing area of ​​the shell increases from nearly zero in the cold state to tens of millimeters in the hot state, causing the high-pressure air to flow through the approximately triangular gap formed between the fan plate and the rotor sealing sheet (see attached Figure 1 ) leaks into the flue gas with lower pressure, greatly increasing the radial air leakage at the hot end of the air preheater. Figure 1 As shown in the figure, the hot end radial seal of the traditional air preheater is composed of the following components: the hot end fan plate 1 is fixed under the hot end shell beam 2 of the air preheater through the inner hanger 3 and the outer hanger 4, and the hot end radial sealing sheet 5 is fixed on the rotor radial partition 7 through the fastener 6. During hot operation, a triangular air leakage area 8 appears between the fan plate and the rotor sealing sheet. According to the assessment, if the air leakage channel here is not treated, the air leakage of the air preheater generated here can reach half of the total air leakage or even more, and increases with the increase of the diameter of the air preheater. The leaking air flow is discharged without participating in the boiler combustion, which increases the air flow resistance in the air preheater and the conveying flow of the fan, increases the power consumption of the fan in the power plant, and reduces the economic efficiency of power generation. If this air leakage is not controlled, the annual power consumption of the induced draft fan and the induced draft fan will be converted into a loss of several million yuan.

[0003] At present, there are two main means to reduce the size of the hot end triangular air leakage area caused by the deformation of the air preheater rotor: one is to set up an automatic adjustment device for the hot end fan plate, and the sealing sheet is pre-installed in a concave shape to offset the influence of the rotor deformation, and the rotor becomes a straight line after deformation; the sensor measures the rotor position after the air preheater deformation, and the control system manipulates the lifting mechanism of the hot end fan plate, and lowers the fan plate to the position close to the rotor sealing sheet to eliminate the triangular air leakage area. This method is widely used in large air preheaters, which can ensure that the fan plate and the sealing sheet do not contact, and there is no operation wear, which can greatly reduce the air leakage. However, the mechanism system is complex, the mechanism for lifting the fan plate works in a high temperature environment, the electrical system is complex, the temperature measurement, contact control components and sensors have a high damage rate, and the failure rate is high. Once the fan plate is damaged and cannot be lifted normally, there is a risk of jamming the air preheater. When the equipment cannot work normally, the fan plate is pulled up, and the hot end radial air leakage rate generated is greater than that of the air preheater without this device, and the operation and maintenance workload is also large. The other method is to set a movable sealing sheet, and use springs and other parts to bounce the sealing sheet to contact the fan plate, thereby reducing the air leakage gap. However, this method has operational wear. The contact pressure between the spring and the fan plate is large at low loads, and there is impact when the sealing sheet passes through the fan plate, causing the fan plate to wear through, the spring to fall off, and the radial partition to tear, resulting in low equipment reliability. The spring used quickly softens and fails at high temperatures, has a short life, a large maintenance workload, and high repair and maintenance costs. Summary of the invention

[0004] The technical problem to be solved by the present invention is that the existing hot end radial seal structure of the air preheater rotor is complicated due to thermal deformation, and the contact pressure between the sealing sheet and the hot end sector plate is large, resulting in poor sealing effect and high maintenance cost.

[0005] In order to solve the above problems, the technical solution of the present invention is to provide a hot end radial sealing device for adaptive air preheater rotor thermal deformation, characterized in that: it includes a fixed sealing structure and a dynamic sealing structure arranged on the rotor radial partition, the fixed sealing structure is a sealing groove, the sealing groove is arranged along the rotor radial direction and is connected and fixed with the rotor radial partition, and the notch direction of the sealing groove is toward the hot end sector plate above the rotor radial partition; the dynamic sealing structure includes a dynamic sealing plate and a compensator, the dynamic sealing plate is arranged in the sealing groove, one end of the dynamic sealing plate close to the rotor center is movably connected to the sealing groove, and the other end is connected to the compensator, and the compensator is connected and fixed to the rotor radial partition; the compensator adopts a telescopic compensation structure, the telescopic compensation direction is opposite to the drooping direction of the rotor periphery, the telescopic compensation amount is consistent with the drooping amount of the rotor periphery, the telescopic compensator drives the dynamic sealing plate to move up and down in the sealing groove to form a dynamic seal between the hot end sector plate, and the fixed sealing structure and the dynamic sealing structure work together to achieve the blocking of the triangular air leakage area.

[0006] Preferably, the compensator is a closed telescopic structure, including a bellows, a base plate and a cover plate, the base plate and the cover plate are respectively arranged at the two ends of the bellows, the three form a closed cavity, the cavity is filled with gas, the gas volume changes with temperature, and the cover plate of the compensator expands and contracts accordingly, the base plate is connected and fixed to the radial partition of the rotor, the outer side of the cover plate is connected and fixed to the dynamic sealing plate, and the inner side of the cover plate is connected to the guide device, the guide device is arranged in the bellows to form a telescopic guide axis to prevent the bellows from tilting after the compensator is loaded.

[0007] Preferably, the guide device comprises a guide cylinder, a mandrel and a mandrel, one end of the mandrel is connected and fixed to the bottom plate, and the other end is connected and fixed to the mandrel, the mandrel is cylindrical, the guide cylinder is sleeved on the mandrel, one end of the guide cylinder is connected to the cover plate, and the mandrel and the inner wall of the guide cylinder form a guide axis. .A hot end radial sealing device for adaptive thermal deformation of air preheater rotor according to claim, characterized in that: the other end of the guide cylinder protrudes toward the inner side of the guide cylinder to form a limit ring for limiting the maximum telescopic compensation amount of the compensator.

[0008] Preferably, the fixed sealing structure comprises a clamping plate sealing sheet and a gasket, and the gasket is arranged between two clamping plate sealing sheets to form a sealing groove.

[0009] Preferably, the dynamic sealing sheet is formed by stacking 1 to 5 thin plates.

[0010] Preferably, a guide fold is provided at one end of the dynamic sealing sheet close to the hot end sector plate.

[0011] Preferably, a sheath is provided on the outer side of the bellows to prevent wear.

[0012] Preferably, a connecting rod is provided on the cover plate, and the cover plate and the dynamic sealing plate are connected and fixed by the connecting rod.

[0013] Preferably, the base plate is connected and fixed to the rotor radial partition plate via a connecting plate.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The present invention divides the sealing plate into a part fixed to the rotor and a movable part. The compensator provides a compensation amount that matches the rotor deformation well, so that the dynamic sealing plate is close to the sealing surface of the fan plate and maintains a certain safety gap. During operation, the hot end fan plate does not need to be adjusted up and down, and the dynamic sealing plate can always stay out of contact with the fan plate. It can automatically adapt to the rotor deformation under different loads, thereby eliminating the hot end triangular air leakage area formed by the rotor deformation and greatly reducing the air preheater leakage rate.

[0016] The height of the compensator can be controlled to be smaller than the distance between the hot end fan plate and the heat transfer element, which can conveniently realize the update and upgrade of the hot end radial seal of the existing air preheater. The existing fan plate can be used without raising the height position of the fan plate. It can completely replace the hot end radial sealing structure such as the hot end fan plate automatic adjustment system and spring seal and overcome their disadvantages.

[0017] All parts are easy to dismantle. The connections between the splint seal, compensator and rotor radial partition are bolted. They can be easily removed when installing or removing the heat transfer element package, and are also easy to restore quickly. It has the advantages of simple structure, no operating wear, low investment, fast construction, less maintenance and high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the hot end triangular air leakage area generated after the rotor is thermally deformed;

[0019] Figure 2 It is a schematic structural diagram of the hot end radial sealing device of the present invention which is adaptive to thermal deformation of the air preheater rotor in a cold state;

[0020] Figure 3 It is a schematic structural diagram of the hot end radial sealing device of the present invention which is adaptive to thermal deformation of the air preheater rotor in a hot state;

[0021] Figure 4 for Figure 3 Section view along AA direction;

[0022] Figure 5 This is the basic internal structure diagram of the compensator.

[0023] Figure 6 This is the relationship diagram between the rotor peripheral sag deformation and compensation amount. DETAILED DESCRIPTION

[0024] In order to make the present invention more clearly understood, preferred embodiments are described in detail below with reference to the accompanying drawings.

[0025] like Figure 4 As shown, the hot end radial sealing device of the adaptive air preheater rotor thermal deformation of the present invention divides the sealing sheet into a fixed part and a movable part with the rotor, including a fixed sealing structure and a dynamic sealing structure, the fixed sealing structure includes a clamping plate sealing sheet 9 and a pad 10, the clamping plate sealing sheet 9 is provided with two layers, and a pad 10 is padded between the two layers of clamping plate sealing sheets 9, the pad 10 is lower than the height of the clamping plate sealing sheet 9 and forms a sealing groove with the clamping plate sealing sheet 9, the clamping plate sealing sheet 9 and the pad 10 are fixed to the near upper end position of the radial partition 7 by fasteners 11, and the notch direction of the sealing groove faces the hot end sector plate 1 above the rotor radial partition 7. A gap equal to the thickness of the pad 10 is reserved at the upper part between the two clamping plate sealing sheets 9 for inserting and installing the dynamic sealing sheet 12.

[0026] The dynamic sealing structure includes a dynamic sealing plate 12 and a compensator 14. The dynamic sealing plate 12 is made of 1 to 5 thin sheets stacked together. In this embodiment, two sheets are used. The total thickness of the dynamic sealing plate 12 is less than that of the gasket 10. The dynamic sealing plate 12 is processed with a guide fold on one side of the sealing surface of the hot end sector plate 1 (processing the guide fold is not a necessary requirement). The dynamic sealing plate 12 and the clamping plate sealing plate 9 are connected by a pin 13 at the inner end near the center of the rotor. The dynamic sealing plate 12 can rotate around the pin 13; the outer end of the dynamic sealing plate 12 is connected to the compensator 14, and the compensator 14 is fixed to the rotor radial partition 7 near the upper end with bolts 15. When the air preheater is in a hot working state, the outer end of the dynamic sealing plate 12 is driven by the expansion and contraction of the compensator 14 to rotate around the inner end pin 13, and slides between the dynamic sealing plate 12 and the sealing groove. The relative positions of the two are determined by Figure 2 becomes Figure 3 As shown, at this time, the dynamic sealing sheet 12 and the clamping plate sealing sheet 9 work together to seal the triangular air leakage area 8 generated by the deformation of the rotor.

[0027] like Figure 5 As shown, the compensator 14 is a closed and retractable structure, which is welded into a closed cavity by a bellows 14-1, a base plate 14-2, and a cover plate 14-3. The cavity is filled with gas, and the volume of the gas changes with the temperature. The compensator 14 expands and contracts accordingly, and the expansion and contraction amount is nearly proportional to the ambient temperature (i.e., the hot end temperature of the air preheater). Since the droop amount of the rotor periphery and the hot end temperature of the air preheater are also basically proportional, by controlling the compensation amount of the compensator 14 with temperature, the outer end of the dynamic sealing plate 12 can always be kept in a position close to the sealing surface of the hot end fan plate 1 and a small gap is maintained, so that it does not contact the hot end fan plate 1 to cause wear, and can automatically adapt to the start and stop process of the air preheater and the change of operating load.

[0028] A sheath 14-4 is provided outside the corrugated section of the bellows 14-1 to prevent the bellows 14-1 from being worn. One side of the bottom plate 14-2 is welded to the connecting plate 14-5. The connecting plate 14-5 is connected to the rotor radial partition plate 7 by bolts 15 to fix the compensator 14 on the rotor. The lower part of the cover plate 14-3 is connected (welded) to the guide cylinder 14-6. A mandrel 14-7 and a mandrel 14-8 are installed in the guide cylinder 14-6. One end of the mandrel 14-8 is connected and fixed to the bottom plate 14-2, and the other end is connected and fixed to the mandrel 14-7. The mandrel 14-7 is cylindrical. The guide cylinder 14-6 is sleeved on the mandrel 14-7. One end of the guide cylinder 14-6 is connected to the cover plate 14-3, and the other end protrudes to the inner side of the guide cylinder 14-6 to form a limit ring 14-10 for limiting the maximum telescopic compensation amount of the compensator 14. The top head 14-7 and the inner wall of the guide cylinder 14-6 form a guide axis to prevent the bellows 14-1 from tilting after the compensator 14 is loaded. A connecting rod 14-9 is provided above the compensator 14 to connect with the dynamic sealing plate 12. In the cold state, the cover plate 14-3 and the top head 14-7 are in contact. When a certain working temperature is reached, the cover plate 14-3 and the top head 14-7 are separated, and the compensator 14 extends upward, driving the outer end of the dynamic sealing plate 12 to move.

[0029] like Figure 4 As shown, the compensator 14 can be arranged on one side of the rotor radial partition 7, or one can be arranged on both sides of the rotor radial partition 7, so that the size of a single compensator 14 can be reduced. When the dynamic sealing plate 12 is too long, a compensator 14 with a compensation amount matching the rotor droop deformation amount at that location can be added at an appropriate position between the inner and outer ends thereof to increase the stability of the dynamic sealing plate 12.

[0030] The material of the compensator 14 must be made of an anti-oxidation material that can withstand working temperatures above 400°C, and the gas filled inside must ensure that it has no corrosive effect on the material of the bellows 14-1. The maximum possible internal pressure of the compensator 14 must be calculated, and the pressure resistance and air tightness tests must be performed at the working temperature.

[0031] The relationship between the compensation amount of the compensator 14 and the droop deformation of the outer circumference of the air preheater rotor is as follows: Figure 6 As shown in the figure (this figure is a typical data of an air preheater with a diameter of 10 meters), under all air preheater operating loads, the compensator 14 can effectively eliminate the droop deformation of the rotor periphery and leave a certain safe operating gap. Since the compensation amount of the compensator 14 depends entirely on the operating temperature, no external intervention is required and basically no maintenance requirements are required.

[0032] The compensator 14 uses a closed gas as the working medium, which is sensitive to temperature. The change in gas volume and temperature are nearly linear. At 350°C, the expansion amplitude of the compensator 14 shell is two orders of magnitude smaller than that of the internal gas, and the expansion of the shell itself has little effect. The internal volume of the compensator 14 is very small, and the metal shell has good heat exchange, so the internal and external temperatures approach each other quickly, and the compensator 14 has sufficient sensitivity to the working temperature. The compensator 14 can achieve the required compensation value by adjusting the axial stiffness (adjusting the thickness) and internal volume of the bellows 14-1. The compensator 14 has a small volume and a small area ratio of shielding the heat transfer element (for a rotor with a diameter of about 10 meters, when all 48 hot end radial partitions are installed, the shielding area of ​​the compensator 14 is less than 1.8% of the heat transfer element installation area, which is only 1 / 5 of the shielding area of ​​the spring seal on the heat transfer element), and the effect on the heat exchange of the air preheater can be ignored. When the compensation amount is large and the size of the compensator 14 is large, several small-diameter compensators 14 can be placed in parallel to reduce the shielding area of ​​the compensator 14 on the heat transfer element.

[0033] Although there is a gap between the dynamic sealing sheet 12 and the plywood sealing sheet 9, the two form a labyrinth seal, and the smoke and air pressure difference when passing through the sealing area makes the dynamic sealing sheet 12 close to the plywood sealing sheet 9 on the low-pressure airflow side, which greatly reduces the amount of air leakage that may pass through this gap. Therefore, the sealing structure of the present invention will not produce excessive additional air leakage.

[0034] The dynamic sealing sheet 12 is generally made of several thin sealing sheets stacked together to ensure sufficient rigidity. When the dynamic sealing sheet 12 is relatively long, some loose connection points can be set between the clamping plate sealing sheet 9 and the dynamic sealing sheet 12 to prevent some foreign objects accidentally brought in by the flue gas from being pulled out when the dynamic sealing sheet 12 is working.

[0035] The total height of the compensator 14 can be controlled to be smaller than the distance between the hot end sector plate 1 and the heat transfer element. Therefore, the present invention can conveniently update and transform the existing hot end radial seal of the air preheater, and can use the existing hot end sector plate 1 without adjusting the height position of the hot end sector plate 1, thereby replacing the traditional sealing structures such as the automatic adjustment system of the hot end sector plate 1 and the spring-type sealing sheet, eliminating their disadvantages. It has the advantages of simple structure, no operation wear, low investment, fast construction, less maintenance and high reliability.

Claims

1. A hot end radial sealing device that is adaptive to thermal deformation of an air preheater rotor, characterized in that: The invention comprises a fixed sealing structure and a dynamic sealing structure arranged on a rotor radial partition (7), wherein the fixed sealing structure is a sealing groove, which is arranged along the rotor radial direction and is connected and fixed to the rotor radial partition (7), and the groove direction of the sealing groove faces the hot end sector plate (1) above the rotor radial partition (7); the dynamic sealing structure comprises a dynamic sealing plate (12) and a compensator (14), wherein the dynamic sealing plate (12) is arranged in the sealing groove, and one end of the dynamic sealing plate (12) close to the rotor center is movably connected to the sealing groove, and the other end is connected to the compensator (14), and the compensator (14) is connected and fixed to the rotor radial partition (7); the compensator (14) adopts a telescopic compensation structure, wherein the telescopic compensation direction is opposite to the rotor outer periphery sagging direction, and the telescopic compensation amount is consistent with the rotor outer periphery sagging amount, and the compensator (14) telescopes to drive the dynamic sealing plate (12) to move up and down in the sealing groove to form a dynamic seal between the hot end sector plate (1), and the fixed sealing structure and the dynamic sealing structure work together to achieve the blocking of the triangular air leakage area (8); The compensator (14) is a closed telescopic structure, comprising a bellows (14-1), a bottom plate (14-2) and a cover plate (14-3). The bottom plate (14-2) and the cover plate (14-3) are respectively arranged at two ends of the bellows (14-1). The three form a closed cavity. The cavity is filled with gas. The volume of the gas changes with temperature, and the cover plate (14-3) of the compensator (14) expands and contracts accordingly. The bottom plate (14-2) is connected and fixed to the rotor radial partition (7). The outer side of the cover plate (14-3) is connected and fixed to the dynamic sealing plate (12). The inner side of the cover plate (14-3) is connected to a guide device. The guide device is arranged in the bellows (14-1) to form a telescopic guide axis to prevent the bellows (14-1) from tilting after the compensator (14) is loaded. The fixed sealing structure comprises a clamping plate sealing sheet (9) and a backing plate (10), wherein the backing plate (10) is arranged between two clamping plate sealing sheets (9) to form a sealing groove; By controlling the compensation amount of the compensator (14) according to the temperature, the outer end of the dynamic sealing plate (12) is always kept close to the sealing surface of the hot end sector plate (1) with a gap and does not contact the hot end sector plate (1).

2. The hot end radial sealing device for adaptive air preheater rotor thermal deformation according to claim 1, characterized in that: The guide device comprises a guide cylinder (14-6), a mandrel (14-7) and a mandrel (14-8); one end of the mandrel (14-8) is connected and fixed to the bottom plate (14-2), and the other end of the mandrel (14-7) is connected and fixed to the mandrel (14-7); the mandrel (14-7) is cylindrical; the guide cylinder (14-6) is sleeved on the mandrel (14-7); one end of the guide cylinder (14-6) is connected to the cover plate (14-3); and the mandrel (14-7) and the inner wall of the guide cylinder (14-6) form a guide axis.

3. The hot end radial sealing device for adaptive air preheater rotor thermal deformation according to claim 2, characterized in that: The other end of the guide cylinder (14-6) protrudes toward the inside of the guide cylinder (14-6) to form a limit ring (14-10) for limiting the maximum telescopic compensation amount of the compensator (14).

4. The hot end radial sealing device for adaptive air preheater rotor thermal deformation according to claim 1, characterized in that: The dynamic sealing sheet (12) is formed by stacking 1 to 5 thin plates.

5. The hot end radial sealing device for adaptive air preheater rotor thermal deformation according to claim 1, characterized in that: The dynamic sealing sheet (12) is provided with a guide folded edge at one end close to the hot end sector plate (1).

6. The hot end radial sealing device for adaptive air preheater rotor thermal deformation according to claim 1, characterized in that: A protective sheath (14-4) is provided on the outer side of the corrugated tube (14-1) to prevent wear.

7. The hot end radial sealing device for adaptive air preheater rotor thermal deformation according to claim 1, characterized in that: A connecting rod (14-9) is provided on the cover plate (14-3), and the cover plate (14-3) and the dynamic sealing plate (12) are connected and fixed via the connecting rod (14-9).

8. The hot end radial sealing device for adaptive air preheater rotor thermal deformation according to claim 1, characterized in that: The bottom plate (14-2) is connected and fixed to the rotor radial partition plate (7) via a connecting plate (14-5).

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