An off-line injection method for an electric-bag dust collector of a power plant boiler

Abstract

This invention discloses an offline pulse-jet cleaning method for an electrostatic precipitator (ESC) baghouse dust collector in a power plant boiler, comprising: preparing for offline pulse-jet cleaning operation; reducing the unit load of the thermal power generating unit; reducing the operating frequency of some induced draft fans in parallel operation and increasing the output of the remaining induced draft fans; closing the offline valves in the dust collector group by group while maintaining pulse-jet cleaning of the filter bags; judging whether the thermal power generating equipment is operating normally based on the operating parameters of the thermal power generating equipment during offline pulse-jet cleaning, and taking corresponding hazard control measures if the thermal power generating equipment is abnormal; opening the offline valves of the dust collector group by group after offline pulse-jet cleaning and coordinating the output balance of the two induced draft fans. This invention controls the upward trend of the differential pressure of the filter bags by adjusting the output of the parallel induced draft fans and closing the offline valves at the dust collector inlet on the side corresponding to the fan with reduced output group by group, continuously activating the filter bag pulse-jet cleaning system.

Description

Technical Field

[0001] This invention belongs to the field of dust collector technology, and particularly relates to an offline pulse-jet cleaning method for an electrostatic precipitator for a power plant boiler. Background Technology

[0002] Currently, the pressure difference between the filter bags in the baghouse dust collector of a power plant boiler tends to increase gradually with the increase of operating time. When the pressure difference is high, it will reduce the performance of the denitrification catalyst in the power plant boiler and reduce the efficiency of the air preheater, resulting in problems such as high exhaust gas temperature at the outlet of the air preheater. In order to suppress the upward trend of the pressure difference between the inlet and outlet of the filter bags in the baghouse dust collector of the power plant boiler, the existing solutions are to perform manual ash cleaning after the thermal power boiler is shut down, or to increase the frequency of bag blowing and increase the pressure of bag blowing during the operation of the thermal power boiler. However, these solutions are all constrained by the power generation task and the compressed air preload, and cannot meet the requirements of long-term, safe and economical operation of thermal power generating units. Summary of the Invention

[0003] To address the problem described in the background art of reducing the pressure difference between the inlet and outlet of the bag filter in a power plant boiler while meeting the requirements for long-term, safe, and economical operation of thermal power generating units, the present invention proposes the following technical solution:

[0004] An offline pulse-jet cleaning method for an electrostatic precipitator in a power plant boiler, the offline pulse-jet cleaning method comprising:

[0005] Prepare for offline blowing operation;

[0006] Reduce the unit load of thermal power generating units;

[0007] Reduce the operating frequency of some induced draft fans in parallel operation and increase the output of the remaining induced draft fans;

[0008] Close the offline valves in the dust collectors one by one, and continue to blow air onto the filter bags;

[0009] Determine whether the thermal power generation equipment is operating normally based on the operating parameters of the thermal power generation equipment during offline injection. If the thermal power generation equipment is abnormal, take corresponding hazard control measures.

[0010] After the offline pulse jetting is completed, the offline valves of the dust collectors are opened one by one, and the output balance of all induced draft fans is coordinated.

[0011] The offline blowing preparation operation includes:

[0012] Check the operating conditions of each jet-blowing unit and each induced draft fan;

[0013] Record the parameters of temperature measuring points, vibration measuring points, and frequency converter during the operation of the electrostatic precipitator in the power plant boiler.

[0014] Control the blowing pressure of the filter bag before offline blowing;

[0015] Maintain the gas pressure in the furnace during operation.

[0016] Furthermore, one of the induced draft fans is maintained at 25Hz-28Hz after the operating frequency is reduced.

[0017] Furthermore, the operating parameters of the thermal power generation equipment include: the temperature of the flue gas at the outlet of the air preheater; the gas pressure in the furnace; and the power generation of the thermal power generation unit.

[0018] Furthermore, the hazard control measures include:

[0019] Increase the output of the blower when the outlet flue gas temperature of the air preheater exceeds the limit;

[0020] In case of abnormal gas pressure in the furnace, increase the output of the booster fan in a timely manner;

[0021] When the equipment operating conditions of a thermal power generation unit are abnormal, offline pulse jetting should be interrupted in a timely manner to restore normal operation.

[0022] Furthermore, the hazard control measures also include immediately manually blowing the corresponding filter bags when the induced draft fan experiences a sudden draft.

[0023] Furthermore, during offline blowing, it is necessary to maintain the pressure difference between the inlet and outlet flue gas of the filter bag at less than 1500 Pa.

[0024] Furthermore, if the outlet flue gas temperature of the air preheater cannot be reduced below the limit value after increasing the output of the blower, the output of the pulverizing system should be reduced at the same time.

[0025] Beneficial effects: This invention controls the rising trend of differential pressure in the filter bags by adjusting the output of parallel induced draft fans and closing the offline valves at the dust collector inlet on the side of the induced draft fan with reduced output one by one, and continuously activating the filter bag blowing system. Attached Figure Description

[0026] Figure 1 A flowchart illustrating an offline pulse-jet cleaning method for an electrostatic precipitator for a power plant boiler, provided according to an embodiment of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this application clearer, the present invention will be described in further detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention.

[0028] It should be understood that the terms “center,” “upper,” “lower,” “front,” “back,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” and “outer,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this patent and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this patent.

[0029] The existing working principle of the electrostatic precipitator (ESP) bag filter for power plant boilers is as follows: When dust-laden flue gas enters the ash hoppers of each compartment within the ESP bag filter, large dust particles are separated and fall directly into the ash hopper under the guidance of the ash hopper guiding system. The remaining dust particles are carried by the airflow into the middle chamber filtration zone, where they are trapped on the outer surface of the filter bags. The purified gas enters the upper inlet chamber through the venturi tubes inside the bags and is then discharged through the lifting valves and exhaust pipes. When the dust accumulation on the filter bag surface reaches a certain amount, the pulse jet cleaning system in the ESP bag filter closes the lifting valves one by one, and sequentially blows the electromagnetic pulse valves in the corresponding chambers of the closed lifting valves. Compressed air rushes into the filter bags through the nozzles, causing the bags to deform radially and shake off the dust, which falls into the ash hopper and is discharged by the ash unloading system. To address the issue mentioned in the background art of reducing the pressure difference between the inlet and outlet of the filter bags in the ESP bag filter for power plant boilers while meeting the requirements of long-term, safe, and economical operation of thermal power generating units, this invention proposes the following technical solution:

[0030] Figure 1 This is a flowchart of an offline pulse-jet cleaning method for an electrostatic precipitator for a power plant boiler, provided according to an embodiment of the present invention.

[0031] Reference Figure 1 An offline pulse-jet cleaning method for a power plant boiler electrostatic precipitator according to an embodiment of the present invention includes the following steps:

[0032] S010, Prepare for offline blowing operation.

[0033] Specifically, preparatory work is required before offline pulse-jet cleaning. This includes checking the operating conditions of each pulse-jet cleaning unit and each induced draft fan; recording the parameters of temperature measuring points, vibration measuring points, and frequency converters to ensure they are within normal ranges while the electrostatic precipitator for the power plant boiler is running; controlling the pulse-jet pressure on the filter bags before offline pulse-jet cleaning; and maintaining the gas pressure in the furnace (the combustion center within the power plant boiler) during operation. In this embodiment, the number of pulse-jet cleaning units is the same as the number of filter bags, and the number of induced draft fans is two.

[0034] S020, Reduce the unit load of thermal power generating units.

[0035] Specifically, after completing the preparations for offline injection, the operator needs to reduce the unit load of the thermal power generating unit to stabilize the boiler combustion. In this embodiment, the unit load of the thermal power generating unit needs to be reduced to 150MW.

[0036] S030, reduce the operating frequency of some induced draft fans in parallel operation and increase the output of the remaining induced draft fans.

[0037] Specifically, taking two induced draft fans as an example, during offline jet cleaning, it is necessary to gradually reduce the operating frequency of one of the two induced draft fans operating in parallel and correspondingly increase the output of the other fan. In this embodiment, the operating frequency of the induced draft fan stabilizes between 25Hz and 28Hz after being reduced.

[0038] S040. Close the offline valves in the dust collectors one by one, and continue to blow air onto the filter bags.

[0039] Specifically, during offline pulse-jet cleaning, the offline valves of the dust collectors on each side need to be closed sequentially while maintaining pulse-jet cleaning of the filter bags, thus keeping the entire thermal power unit operating at a low load. After closing the offline valves of the dust collectors on each side, the gas pressure inside the furnace also needs to be adjusted to maintain a stable negative pressure during offline pulse-jet cleaning, until all offline valves of the dust collectors on each side are completely closed. This prevents high-temperature flue gas from escaping into the external environment, thereby avoiding safety hazards such as pollution, burns to equipment, and injuries to personnel. In this embodiment, after closing the offline valves of the dust collectors on each side sequentially, the pulse-jet pressure of the filter bags is always maintained above 500 Pa, and during offline pulse-jet cleaning, the pressure difference between the inlet and outlet flue gas of the filter bags needs to be maintained below 1500 Pa.

[0040] S050. Determine whether the thermal power generation equipment is operating normally based on the operating parameters of the thermal power generation equipment during offline injection. If the thermal power generation equipment is abnormal, take corresponding hazard control measures.

[0041] Specifically, during offline injection, it is also necessary to monitor operating parameters such as the temperature of the flue gas at the outlet of the air preheater, the gas pressure in the furnace, and the power generation of the thermal power unit to determine whether the thermal power equipment is operating normally. When operating parameters are abnormal, corresponding hazard control measures are taken to stabilize the offline injection process.

[0042] During offline pulse-jet cleaning, the increased flue gas intake of the operating air preheater leads to a rise in its outlet flue gas temperature. Since the exhaust gas from the air preheater enters the filter bags of the electrostatic precipitator in the power plant boiler, excessively high outlet flue gas temperatures can cause direct damage to the filter bags, thus affecting dust removal operations. When the outlet flue gas temperature exceeds a certain limit, the output of the single-sided blower needs to be increased to reduce the heating time of the flue gas within the air preheater, thereby lowering the outlet flue gas temperature. In this embodiment, the outlet flue gas temperature limit is 160°C. If increasing the blower output still fails to lower the air preheater's outlet temperature, the output of the pulverizing system needs to be reduced, provided boiler combustion is stable, to further reduce the outlet flue gas temperature within the air preheater.

[0043] The high-temperature flue gas flow path within the power plant boiler is as follows: tail heating surface, denitrification equipment, air preheater, electrostatic precipitator, induced draft fan, booster fan, desulfurization equipment, and chimney. The entire flue gas system within the power plant boiler maintains negative pressure operation through both induced draft fans and booster fans. If the furnace within the power plant boiler cannot maintain negative pressure, the mill is shut down, the pulverized coal pipes are thoroughly purged, the auxiliary air main valve for the shut-down mill is closed, and the sealing air cooling pulverized coal pipes are appropriately opened. Then, the output of the booster fan is increased to maintain the pressure at the booster fan inlet at -800 Pa.

[0044] If, during offline pulse-jet cleaning, the power generation of the thermal power generation units in the power plant boiler is abnormal, this abnormality is due to severely deteriorated boiler combustion or even flameout (combustion conditions of pulverized coal in the furnace), auxiliary equipment tripping, etc. In this case, offline pulse-jet cleaning needs to be immediately interrupted to restore normal operation. In this embodiment, if, during offline pulse-jet cleaning, a higher pulse-jet pressure needs to be maintained, the pulse-jet frequency of other filter bags will decrease, potentially causing an increase in the pressure difference of other filter bags. This can lead to abnormal noises and vibrations from the induced draft fan and flue, resulting in a "stealing air" phenomenon that can damage equipment. This is because when the two induced draft fans are operating in parallel, the operating conditions are unstable, with large fluctuations in parameters such as air pressure and flow rate. The dampers of the two induced draft fans may be significantly closed or opened, disrupting the balance of the parallel operation. In this case, manual pulse-jet cleaning of the corresponding filter bags is necessary to alleviate the damage caused by the induced draft fan stealing air.

[0045] S060. After the offline pulse jetting ends, open the offline valves of the dust collectors one by one and coordinate the output balance of all induced draft fans.

[0046] Specifically, after the offline pulse-jet cleaning is completed, the normal operation of the power plant boiler electrostatic precipitator needs to be restored by opening the closed offline valves of the dust collector group by group. Each time a group of offline valves is opened, the negative pressure in the furnace needs to be readjusted to the normal value before opening the next group, until all the solenoid valves that were closed during the offline pulse-jet cleaning process are opened, and then the balance between the output of all induced draft fans is coordinated, thus completing the entire offline pulse-jet cleaning operation.

[0047] In summary, this invention controls the upward trend of the differential pressure of the filter bags by adjusting the output of the parallel induced draft fans and closing the offline valves at the dust collector inlet on the side corresponding to the reduced output induced draft fans one by one, and continuously activating the dust collector bag cleaning system.

[0048] The foregoing has described specific embodiments of the invention. Other embodiments are within the scope of the appended claims.

[0049] The terms “exemplary,” “example,” etc., used throughout this specification mean “serving as an example, instance, or illustration” and do not imply “preferred” or “advantageous” than other embodiments. Detailed descriptions are included for the purpose of providing an understanding of the described techniques. However, these techniques can be practiced without these detailed descriptions. In some instances, well-known structures and apparatuses are shown in block diagram form to avoid obscuring the concepts of the described embodiments.

[0050] The optional embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details in the above embodiments. Within the scope of the technical concept of the embodiments of the present invention, various simple modifications can be made to the technical solutions of the embodiments of the present invention, and these simple modifications all fall within the protection scope of the embodiments of the present invention.

[0051] The foregoing description of this specification is provided to enable any person skilled in the art to implement or use the content of this specification. Various modifications to the content of this specification will be apparent to those skilled in the art, and the general principles defined herein can be applied to other variations without departing from the scope of protection of this specification. Therefore, this specification is not limited to the examples and designs described herein, but is consistent with the widest scope of the principles and novel features disclosed herein.

Claims

1. An off-line injection method for an electric station boiler electric bag precipitator, characterized by, The off-line injection method comprises: preparing off-line injection operation; reducing the unit load of the thermal power generating unit; reducing the working frequency of part of the induced draft fans in parallel operation and increasing the output of the remaining induced draft fans; closing the off-line valves in the dust collector in groups and maintaining injection on the cloth bag; judging whether the thermal power generating equipment is normally operated according to the operating parameters of the thermal power generating equipment during off-line injection, and if the thermal power generating equipment is abnormal, taking corresponding dangerous control measures; opening the off-line valves of the dust collector in groups after the off-line injection is completed and coordinating the output balance of all induced draft fans.

2. The off-line injection method of an electric station boiler electric bag precipitator according to claim 1, characterized in that, The preparing off-line injection operation comprises: checking the operating conditions of each injection unit and each induced draft fan; recording the parameters of temperature measuring points, vibration measuring points and frequency converters when the power station boiler electric bag dust collector is operated; controlling the injection pressure of the cloth bag before off-line injection; maintaining the air pressure when the furnace is operated.

3. The off-line injection method of an electric station boiler electric bag precipitator according to claim 2, characterized in that, The one of the induced draft fans is maintained at 25-28 Hz after reducing the working frequency.

4. The off-line injection method of an electric station boiler electric bag precipitator according to claim 1, characterized in that, The operating parameters of the thermal power generating equipment include the temperature of the outlet flue gas of the air preheater, the air pressure of the furnace and the power generation of the thermal power generating unit.

5. The off-line injection method of an electric station boiler electric bag precipitator according to claim 4, characterized in that, The dangerous control measures comprise: increasing the output of the forced draft fan when the outlet flue gas temperature of the air preheater exceeds the limited value; timely increasing the output of the booster fan in the abnormal state of the air pressure of the furnace; timely interrupting the off-line injection and restoring the normal operation mode when the operating conditions of the equipment of the thermal power generating unit are abnormal.

6. The off-line injection method of an electric station boiler electric bag precipitator according to claim 5, characterized in that, The dangerous control measures further comprise manually injecting the corresponding cloth bag immediately when the induced draft fan occurs wind stealing.

7. The off-line injection method of an electric station boiler electric bag precipitator according to claim 1, characterized in that, During the off-line injection, the pressure difference of the inlet and outlet flue gas of the cloth bag needs to be maintained less than 1500 Pa.

8. The off-line injection method of an electric station boiler electric bag precipitator according to claim 5, characterized by, If the outlet flue gas temperature of the air preheater cannot be reduced below the limited value after increasing the output of the forced draft fan, the output of the pulverizing system is simultaneously reduced.

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