PLC-based air preheater soot blowing control system

Abstract

The utility model discloses a kind of PLC-based air preheater soot blowing control system, including temperature detection module, soot blowing module, cleaning medium conveying module and control system: wherein, the temperature detection module is arranged at the hot end of air preheater secondary air duct, temperature detection module includes multiple temperature detection units, multiple temperature detection units are arranged along the radial direction of the rotor of air preheater, and each temperature detection unit corresponds the compartment of rotor;By detecting the air temperature of the upper portion of rotor compartment (sector), the compartment (sector) of rotor that occurs blockage is judged, and then the walking mechanism of soot blowing module is driven by programmable controller (PLC) to control soot blower to operate to the blockage area of rotor, accurate cleaning is carried out to the rotor compartment (sector) that occurs blockage, the feedback of temperature detection module judges the blockage degree of rotor, and then by controlling the pressure and flow of cleaning medium, further improve cleaning efficiency.

Description

Technical Field

[0001] This utility model belongs to the field of soot blower technology, specifically a PLC-based soot blowing control system for air preheaters. Background Technology

[0002] An air preheater, also known simply as an air preheater, is a preheating device used to improve the heat exchange performance of a boiler and reduce heat loss. The function of an air preheater is to transfer the heat carried by the flue gas discharged from the boiler's tail flue to the air entering the boiler through heat exchange fins, preheating the air to a certain temperature. Air preheaters are mainly divided into two types: tube-and-box type and rotary type. The rotary type, due to its compact structure and higher efficiency, has become the standard configuration for modern large-scale power plant boilers and industrial boilers.

[0003] To prevent blockage of the rotor compartment in a rotary air preheater, a sootblower is typically required. A traveling mechanism drives the sootblower to reciprocate along the radial direction of the rotor to clean it. For example, Chinese utility model patent CN215598203U discloses an air preheater sootblower, which includes a sootblower body, a sootblower support, a main sootblowing pipe, a pair of first branch pipes, and a pair of second branch pipes. The sootblower body includes a sootblower beam, a trolley, a gun barrel, and a lifting valve. The trolley is mounted on the sootblower beam and moves back and forth along the bottom rack of the beam. The gun barrel is mounted on the trolley, and the lifting valve is installed at one end of the beam. The outlet of the lifting valve is connected to the inlet of the gun barrel. The valve is opened or closed by a valve opening device on the trolley. The nozzles on the first branch pipes perform initial purging, and the nozzles on the second branch pipes perform secondary purging, improving the purging effect.

[0004] Since the multiple compartments of the air preheater rotor do not usually become clogged at the same time, the existing soot blowing devices for rotary air preheaters (such as the aforementioned utility model patent) usually clean the soot blowing gun by driving the trolley of the traveling mechanism to reciprocate with the rotor radius as the stroke. However, they cannot selectively clean the clogged areas of the rotor, so the cleaning efficiency needs to be improved. Utility Model Content

[0005] This invention proposes a PLC-based air preheater soot blowing control system, which aims to solve the problem that existing air preheater soot blowing devices cannot selectively clean the blocked areas of the rotor.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A PLC-based air preheater soot blowing control system includes a temperature detection module, a soot blowing module, a cleaning medium conveying module, and a control system. The temperature detection module is located at the hot end of the secondary air duct of the air preheater. The temperature detection module includes multiple temperature detection units, which are arranged along the radial direction of the rotor of the air preheater. Each temperature detection unit corresponds to a compartment of the rotor. The soot blowing module includes a walking mechanism and a soot blower. The walking mechanism is fixedly installed on the outside of the air preheater housing. The actuator of the walking mechanism extends into the air preheater housing and is connected to the soot blower. A displacement sensor is installed on the walking mechanism. The cleaning medium conveying module includes a high-pressure water conveying component and a steam conveying component, which are connected to a soot blower. The control system includes a programmable controller. The signal input terminal of the programmable controller is connected to a temperature detection module and a displacement sensor. The output terminal of the programmable controller is connected to the drive motor of the walking mechanism through a first frequency converter.

[0007] Preferably, the high-pressure water delivery assembly includes a water pump, the outlet of which is connected to a high-pressure switching valve. The outlet of the high-pressure switching valve is connected to a soot blower via a first pressure regulating valve. A first pressure transmitter is provided between the first pressure regulating valve and the soot blower. The signal output of the first pressure transmitter is connected to the input of a programmable controller, and the output of the programmable controller is electrically connected to the first pressure regulating valve.

[0008] Preferably, the output terminal of the programmable controller is connected to a second frequency converter, and the output terminal of the second frequency converter is connected to the drive motor of the water pump.

[0009] Preferably, the steam delivery assembly includes a steam pipe connected to the soot blower, a second pressure regulating valve is provided on the steam pipe, a second pressure transmitter is provided on the steam pipe between the outlet end of the second pressure regulating valve and the soot blower, the signal output end of the second pressure transmitter is connected to the input end of the programmable controller, and the output end of the programmable controller is electrically connected to the second pressure regulating valve.

[0010] Preferably, the temperature detection unit includes a set of thermocouple temperature sensors and a set of infrared temperature sensors. The thermocouple temperature sensors are used to measure the temperature of the secondary airflow, and the infrared temperature sensors are used to measure the surface temperature of the air preheater rotor.

[0011] Preferably, it also includes a DCS control system, wherein the programmable controller is connected via fieldbus or industrial Ethernet.

[0012] Preferably, the soot blowing module is located at the hot end of the secondary air duct of the air preheater, and the soot blowers of the two air preheater soot blowing modules are connected to a water pump.

[0013] Preferably, the soot blowing module is located at the cold end and the hot end of the secondary air duct of the air preheater. The soot blowers located at the cold ends of the two air preheaters are connected to a water pump, and the soot blowers located at the hot ends of the two air preheaters are connected to another water pump.

[0014] Beneficial effects: Compared with the prior art, the present invention can achieve at least the following technical effects: 1. The temperature detection module of this utility model has multiple temperature detection units distributed in the areas corresponding to multiple compartments (sectors) of the rotor. By detecting the air outlet temperature at the top of the rotor compartment (sector), the compartment (sector) of the rotor that is blocked is determined. Then, the programmable controller (PLC) controls the walking mechanism of the soot blowing module to drive the soot blower to the blocked area of ​​the rotor, and performs precise cleaning on the blocked rotor compartment (sector), thereby improving cleaning efficiency and saving cleaning media.

[0015] 2. The control system of this utility model can use the feedback from the temperature detection module to determine the degree of blockage of the air preheater rotor, and then control the pressure and flow rate of the cleaning medium by controlling the opening of the pressure regulating valve or the output power of the water pump, thereby further improving the cleaning efficiency. Attached Figure Description

[0016] Figure 1 This is a schematic diagram showing the connection relationship between the modules of this utility model.

[0017] Figure 2 This is a schematic diagram of the single-system cleaning structure of two air preheaters in an embodiment of this utility model.

[0018] Figure 3 This is a schematic diagram of the dual-system cleaning structure of two air preheaters in an embodiment of this utility model.

[0019] In the diagram: 1. Rotor; 2. Compartment; 3. Traveling mechanism; 4. First frequency converter; 5. Second frequency converter; 6. Water pump; 7. High-pressure switching valve; 8. First pressure regulating valve; 9. Second pressure regulating valve; 10. First pressure transmitter; 11. Second pressure transmitter; 12. Programmable controller; 13. DCS control system; 14. Temperature detection module; 141. Temperature detection unit; 15. Soot blower; 16. Speed ​​sensor; 17. Displacement sensor. Detailed Implementation

[0020] The present invention will be further explained below with reference to specific implementation examples.

[0021] Please see Figure 1-3 This utility model proposes a PLC-based air preheater soot blowing control system, including a temperature detection module 14, a soot blowing module, a cleaning medium conveying module, and a control system. The temperature detection module 14 is located at the hot end of the secondary air duct of the air preheater. The temperature detection module 14 includes multiple temperature detection units 141, which are arranged along the radial direction of the rotor 1 of the air preheater. Each temperature detection unit 141 corresponds to a compartment 2 of the rotor 1. It is used to detect the outlet air temperature above the corresponding compartment 2 on the rotor 1. The soot blowing module includes a walking mechanism 3 and a soot blower 15. The walking mechanism 3 is fixedly installed on the outside of the air preheater housing. The actuator end of the walking mechanism 3 extends into the air preheater housing and is connected to the soot blower 15. A displacement sensor 17 is provided on the walking mechanism 3. The walking mechanism 3 is used to drive the soot blower 15 to the compartment where the rotor 1 is blocked (or multiple adjacent compartments 2 of the rotor 1 can be defined as a sector, and each sector corresponds to a set of temperature detection units). The soot blower 15 sprays cleaning medium to clean the area where the rotor 1 is blocked.

[0022] The cleaning medium conveying module includes a high-pressure water conveying component and a steam conveying component, which are connected to the soot blower 15. The high-pressure water conveying component and the steam conveying component convey high-pressure steam and high-pressure water to the soot blower, wherein the high-pressure steam can be derived from the boiler's induced steam. The control system includes a programmable controller 12. The signal input terminal of the programmable controller 12 is connected to the temperature detection module 14 and the displacement sensor 17. The output terminal of the programmable controller 12 is connected to the drive motor of the walking mechanism 3 through the first frequency converter 4.

[0023] like Figure 1 As shown, the temperature detection unit 141 transmits the secondary air outlet temperature of the corresponding compartment 2 (or sector) of rotor 1 to the programmable controller 12. When the compartment 2 of rotor 1 is blocked, the outlet air temperature of its corresponding area will decrease. The programmable controller 12 determines the compartment 2 of rotor 1 that is blocked based on the feedback from the temperature detection unit 141 and sends a control command to the first frequency converter 4. The first frequency converter 4 sends a speed or torque command to the drive motor of the walking mechanism 3 according to the command of the programmable controller 12, thereby driving the soot blower 15 to run to the designated area. The displacement sensor 17 feeds back the position information of the soot blower 15 to the programmable controller 12 in real time. The programmable controller 12 reads the actual position signal fed back by the displacement sensor 17 and executes PID control.

[0024] In this embodiment, the high-pressure water delivery assembly includes a water pump 6, the outlet of which is connected to a high-pressure switching valve 7. The outlet of the high-pressure switching valve 7 is connected to a soot blower 15 via a first pressure regulating valve 8. A first pressure transmitter 10 is provided between the first pressure regulating valve 8 and the soot blower 15. The signal output terminal of the first pressure transmitter 10 is connected to the input terminal of a programmable controller 12, and the output terminal of the programmable controller 12 is electrically connected to the first pressure regulating valve 8.

[0025] The water pump 6 is a high-pressure water pump, such as the high-pressure water pump disclosed in Chinese Utility Model Patent CN204148200U. The high-pressure switching valve 7 is used to switch the output pressure and flow rate of the high-pressure water. The programmable controller 12 adjusts the high-pressure water pressure input to the soot blower 15 by adjusting the opening of the first pressure regulating valve 8 according to the feedback from the temperature detection module 14. The first pressure transmitter 10 feeds back the water pressure signal input to the soot blower 15 to the programmable controller 12, and the programmable controller 12 performs closed-loop regulation according to the feedback from the first pressure transmitter 10.

[0026] In this embodiment, the output terminal of the programmable controller 12 is connected to a second frequency converter 5, and the output terminal of the second frequency converter 5 is connected to the drive motor of the water pump 6.

[0027] In addition, the rotational speed of rotor 1 can be detected by rotational speed sensor 16, and the input pressure and flow rate of cleaning medium can be controlled according to the rotational speed of rotor 1.

[0028] The programmable controller 12 can also change the output power of the water pump 6 through the second frequency converter 5, thereby adjusting the high-pressure water pressure input to the soot blower 15. For example, when one water pump 6 is connected to two soot blowers 15, if the pressure required for cleaning is still not met when the opening of the first pressure regulating valve reaches its maximum, the programmable controller 12 will send speed or torque commands to the motor of the water pump 6 through the second frequency converter 5 to increase the output power of the water pump 6.

[0029] In this embodiment, the steam delivery assembly includes a steam pipe connected to the soot blower 15. A second pressure regulating valve 9 is provided on the steam pipe. A second pressure transmitter 11 is provided on the steam pipe between the outlet end of the second pressure regulating valve 9 and the soot blower 15. The signal output end of the second pressure transmitter 11 is connected to the input end of the programmable controller 12. The output end of the programmable controller 12 is electrically connected to the second pressure regulating valve 9.

[0030] In this embodiment, the programmable controller 12 can also adjust the steam pressure input to the soot blower 15 by adjusting the opening of the second pressure regulating valve 11 based on the feedback from the temperature detection module 14. The second pressure transmitter 11 is used to feed back the steam pressure signal to the programmable controller 12 to realize closed-loop regulation.

[0031] In this embodiment, the temperature detection unit 141 is further configured to include a set of thermocouple temperature sensors and a set of infrared temperature sensors. The thermocouple temperature sensors are used to measure the temperature of the secondary airflow, and the infrared temperature sensors are used to measure the surface temperature of the air preheater rotor.

[0032] Among them, the thermocouple temperature sensor is used to detect the outlet air temperature, and the infrared temperature sensor is used to detect the rotor surface temperature. The cooperation of the two sets of sensors further improves the detection temperature. For example, when rotor 1 is blocked, the outlet air temperature will decrease, while the surface temperature of rotor 1 will increase. The difference between the temperatures of the two sets of sensors is used to determine whether rotor 1 is blocked, which is more accurate.

[0033] This embodiment is further configured to include a DCS control system 13, wherein the programmable controller 12 is connected via a fieldbus or industrial Ethernet.

[0034] Through the DCS control system 13, the entire power plant's massive control system can be divided into multiple relatively independent sub-control systems. Operators can monitor, operate, handle alarms, and optimize the operation status of each subsystem in the central control room. This achieves unified management and scheduling of information across the entire plant. Specifically, in this embodiment, the programmable logic controller 12 (PLC) can connect to the DCS control system via fieldbus protocols (such as Modbus RTU / ASCII or Profibus-DP). A single bus cable can transmit hundreds or thousands of data points, saving significant costs on cables and I / O modules. The programmable controller 12 and the DCS control system can also be connected via industrial Ethernet (such as Modbus TCP / IP protocol), which offers higher speed and openness.

[0035] In this embodiment, the soot blowing module is located at the hot end of the secondary air duct of the air preheater, and the soot blowers 15 of the two air preheater soot blowing modules are connected to a water pump 6.

[0036] Figure 2 Two single-system cleaning structures for air preheaters are shown. The single-system cleaning only cleans the hot end of rotor 1, and the structure is relatively simple.

[0037] In this embodiment, the soot blowing module is set at the cold end and the hot end of the secondary air duct of the air preheater. The soot blowers 15 located at the cold ends of the two air preheaters are connected to a water pump 6, and the soot blowers 15 located at the hot ends of the two air preheaters are connected to another water pump 6.

[0038] Figure 3 The dual-system cleaning structure of two air preheaters is shown. Both the cold and hot ends of rotor 1 are equipped with soot blowing modules. The soot blower 15 at the hot end cleans downwards, while the soot blower at the cold end cleans upwards, further improving cleaning efficiency.

[0039] In the description of this utility model, the term "multiple" refers to two or more. Unless otherwise explicitly defined, the terms "upper," "lower," "left," "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this utility model 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 utility model. The terms "connection," "installation," "fixing," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.

[0040] In the description of this utility model, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this utility model. In this utility model, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0041] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A PLC-based air preheater soot blowing control system, characterized in that, Includes a temperature detection module (14), a soot blowing module, a cleaning medium conveying module, and a control system: The temperature detection module (14) is located at the hot end of the secondary air duct of the air preheater. The temperature detection module (14) includes multiple temperature detection units (141). The multiple temperature detection units (141) are arranged along the radial direction of the rotor (1) of the air preheater. Each temperature detection unit (141) corresponds to a compartment (2) of the rotor (1). The soot blowing module includes a walking mechanism (3) and a soot blower (15). The walking mechanism (3) is fixedly installed on the outside of the air preheater housing. The execution end of the walking mechanism (3) extends into the air preheater housing and is connected to the soot blower (15). A displacement sensor (17) is provided on the walking mechanism (3). The cleaning medium conveying module includes a high-pressure water conveying component and a steam conveying component, which are connected to the soot blower (15). The control system includes a programmable controller (12), the signal input terminal of which is connected to a temperature detection module (14) and a displacement sensor (17), and the output terminal of the programmable controller (12) is connected to the drive motor of the walking mechanism (3) through a first frequency converter (4).

2. The PLC-based air preheater soot blowing control system according to claim 1, characterized in that, The high-pressure water delivery assembly includes a water pump (6), the outlet of which is connected to a high-pressure switching valve (7). The outlet of the high-pressure switching valve (7) is connected to a soot blower (15) via a first pressure regulating valve (8). A first pressure transmitter (10) is provided between the first pressure regulating valve (8) and the soot blower (15). The signal output of the first pressure transmitter (10) is connected to the input of a programmable controller (12). The output of the programmable controller (12) is electrically connected to the first pressure regulating valve (8).

3. The PLC-based air preheater soot blowing control system according to claim 2, characterized in that, The output of the programmable controller (12) is connected to a second frequency converter (5), and the output of the second frequency converter (5) is connected to the drive motor of the water pump (6).

4. The PLC-based air preheater soot blowing control system according to claim 1, characterized in that, The steam delivery assembly includes a steam pipe connected to the soot blower (15), a second pressure regulating valve (9) is provided on the steam pipe, a second pressure transmitter (11) is provided on the steam pipe between the outlet end of the second pressure regulating valve (9) and the soot blower (15), the signal output end of the second pressure transmitter (11) is connected to the input end of the programmable controller (12), and the output end of the programmable controller (12) is electrically connected to the second pressure regulating valve (9).

5. The PLC-based air preheater soot blowing control system according to claim 1, characterized in that, The temperature detection unit (141) includes a set of thermocouple temperature sensors and a set of infrared temperature sensors. The thermocouple temperature sensors are used to measure the temperature of the secondary airflow, and the infrared temperature sensors are used to measure the surface temperature of the air preheater rotor.

6. The PLC-based air preheater soot blowing control system according to claim 1, characterized in that, It also includes a DCS control system (13), the programmable controller (12) being connected via fieldbus or industrial Ethernet.

7. The PLC-based air preheater soot blowing control system according to claim 3, characterized in that, The soot blowing module is located at the hot end of the secondary air duct of the air preheater, and the soot blowers (15) of the two air preheaters are connected to a water pump (6).

8. The PLC-based air preheater soot blowing control system according to claim 3, characterized in that, The soot blowing module is located at the cold end and the hot end of the secondary air duct of the air preheater. The soot blowers (15) located at the cold end of the two air preheaters are connected to a water pump (6), and the soot blowers (15) located at the hot end of the two air preheaters are connected to another water pump (6).

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