Boiler induced draft fan control system and boiler system

Abstract

The application discloses a boiler induced draft fan control system and a boiler system, which comprises a high-voltage frequency converter, an induced draft fan assembly and a distributed control system. A power input end of the high-voltage frequency converter is used for being connected with an external power supply, and an output end of the high-voltage frequency converter is connected with a power input end of the induced draft fan assembly through a power cable. An air outlet of the induced draft fan assembly is used for being connected to a boiler flue. The distributed control system is respectively connected with a control end of the high-voltage frequency converter and a communication connection through a control circuit. The distributed control system is connected with a monitoring instrument of the boiler in communication, and the monitoring instrument is used for acquiring real-time operation parameters of the boiler. The boiler induced draft fan control system and the boiler system realize the matching of the induced draft system and the boiler load. Compared with the existing single manual control mode, the system can improve the energy utilization efficiency of the induced draft fan assembly, that is, reduce the power consumption of the induced draft fan motor and the overall operation cost.

Description

Technical Field

[0001] This utility model belongs to the technical field of boiler equipment, specifically relating to a boiler induced draft fan control system and a boiler system. Background Technology

[0002] In the operation of boilers in industries such as thermal power generation and heating, the induced draft system is one of the boiler equipment. Its function is to continuously discharge the flue gas generated by boiler combustion from the furnace and maintain a stable negative pressure environment. The operating status of the induced draft fan will affect the boiler's combustion efficiency, safety and energy consumption level.

[0003] Traditional boiler induced draft control methods are usually quite simple. On the one hand, the constant power operation of the induced draft fan will result in significant energy waste, and the direct start-up of the induced draft fan will have a large impact on the power grid and increase maintenance costs. On the other hand, it is difficult for operators to manually adjust the operating power of the induced draft fan according to changes in multiple parameters such as boiler load, temperature, and coal quantity. Utility Model Content

[0004] This application proposes a boiler induced draft fan control system and a boiler system, which can adapt and adjust the operating status of the boiler induced draft fan, thereby reducing the energy consumption and operating cost of the boiler fan.

[0005] To achieve the above objectives, this utility model provides the following technical solution: A boiler induced draft fan control system includes: a high-voltage frequency converter, an induced draft fan assembly, and a distributed control system; The power input terminal of the high-voltage frequency converter is used to connect to an external power source, and the output terminal of the high-voltage frequency converter is connected to the power input terminal of the induced draft fan assembly via a power cable. The air outlet of the induced draft fan assembly is used to connect to the boiler flue; The distributed control system is connected to the control terminal of the high-voltage frequency converter and communicates with it via a control circuit. The distributed control system is also connected to the boiler's monitoring instruments, which are used to acquire the boiler's real-time operating parameters.

[0006] In one embodiment of this application, the real-time operating parameters of the boiler include at least one of the following: boiler furnace negative pressure, flue gas oxygen content, main steam pressure, total boiler air volume, and coal feed rate.

[0007] In one embodiment of this application, the induced draft fan assembly includes an induced draft fan motor and an induced draft fan body, wherein the output shaft of the induced draft fan motor is connected to the induced draft fan body in a transmission manner.

[0008] In one embodiment of this application, the moving blades of the induced draft fan body are connected to the moving blade adjustment actuator, and the moving blade adjustment actuator is communicatively connected to the distributed control system.

[0009] In one embodiment of this application, the moving blade adjusting actuator is an electric actuator or a hydraulic actuator.

[0010] In one embodiment of this application, the distributed control system is a DCS system or a PLC control system.

[0011] A boiler system includes a boiler body and a boiler induced draft fan control system, wherein the outlet of the induced draft fan assembly of the boiler induced draft fan control system is connected to the flue of the boiler body.

[0012] In summary, the technical solution proposed in this application has the following beneficial technical effects: This application integrates the boiler's operating parameters through a distributed control system, and coordinates the control of the high-voltage frequency converter, motor speed, and the opening of the induced draft fan's outlet blades, thereby achieving the matching of the induced draft system with the boiler load. Compared with the existing single manual control method, this system can improve the energy utilization efficiency of the induced draft fan components, that is, reduce the power consumption of the induced draft fan motor and the overall operating cost. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of the structure of a boiler induced draft fan control system provided in an embodiment of this application; Figure 2 This is a schematic diagram of the structure of a boiler induced draft fan control system provided in an embodiment of this application; Figure 3 A schematic diagram of the moving blade structure of the induced draft fan body in a boiler induced draft fan control system provided in an embodiment of this application; Figure 4 A schematic diagram of the working process of a boiler induced draft fan control system provided in an embodiment of this application.

[0015] In the diagram: 1. High-voltage frequency converter; 2. Exhaust fan assembly; 21. Exhaust fan motor; 22. Exhaust fan body; 3. Distributed control system; 4. Monitoring instrument; 5. Moving blade adjustment actuator; 51. Moving blade. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are also within the scope of protection of this application.

[0017] It should be noted that in the description of this application, the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" 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 application 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 application.

[0018] In this application, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art will understand the specific meaning of these terms in this application based on the specific circumstances.

[0019] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0020] This embodiment provides a boiler induced draft fan control system, see reference. Figures 1-4 As shown, it includes: a high-voltage frequency converter 1, an induced draft fan assembly 2, and a distributed control system 3; The power input terminal of the high-voltage frequency converter 1 is used to connect to an external power source, and the output terminal of the high-voltage frequency converter 1 is connected to the power input terminal of the induced draft fan assembly 2 via a power cable. The air outlet of the induced draft fan assembly 2 is used to connect to the boiler flue; In the above embodiment, the distributed control system 3 is communicatively connected to the control terminal of the high-voltage frequency converter 1 through the control circuit. The distributed control system 3 is communicatively connected to the boiler monitoring instrument 4. The monitoring instrument 4 is used to obtain the real-time operating parameters of the boiler. In addition, the high-voltage frequency converter 1 has a soft start function, for example, the starting current can be controlled within 1.2 times the rated current, which reduces the impact on the power grid and mechanical transmission system, extends the service life of the equipment, and reduces maintenance costs.

[0021] In one embodiment of this application, the real-time operating parameters of the boiler include at least one of the following: boiler furnace negative pressure, flue gas oxygen content, main steam pressure, total boiler air volume, and coal feed rate.

[0022] In one embodiment of this application, see [reference] Figure 2 As shown, the induced draft fan assembly 2 includes an induced draft fan motor 21 and an induced draft fan body 22, and the output shaft of the induced draft fan motor 21 is connected to the induced draft fan body 22 in a transmission connection.

[0023] In the above embodiments, the induced draft fan motor 21 and the induced draft fan body 22 are connected by a coupling, which has a clear structure, direct transmission, and facilitates equipment installation and maintenance.

[0024] In one embodiment of this application, see [reference] Figure 2 As shown, the moving blades of the induced draft fan body 22 are connected to the moving blade adjustment actuator 5 via a transmission, and the moving blade adjustment actuator 5 is connected to the distributed control system via a communication connection.

[0025] In the above embodiment, the distributed control system 3 is used to generate a coordinated control command based on the real-time boiler operating parameters obtained from the monitoring instrument 4, and synchronously send it to the blade adjustment actuator 5 to coordinately adjust the speed of the induced draft fan motor 21 and the deflection degree of the blades of the induced draft fan body 22. The two work together to obtain a larger air volume adjustment range and a faster response speed. That is, the blade adjustment actuator 5 controls the deflection of the blades to adjust the cross-sectional area of ​​the fan blades of the fan body 22, thereby adjusting the airflow generated by the fan blade rotation. The distributed control system adjusts the input voltage power of the induced draft fan motor 21 through the high-voltage frequency converter 1, for example, by reducing the input voltage power to control the operating power of the induced draft fan motor 21 to decrease, thereby reducing the output speed of the induced draft fan motor 21.

[0026] In one embodiment of this application, the moving blade adjusting actuator 5 is an electric actuator or a hydraulic actuator.

[0027] In the above embodiments, electric actuators (such as Siemens SIPOS) are easy to install and wire, and have high control precision; hydraulic actuators have large output torque, are suitable for large fans, have fast response speed, and can be selected according to actual needs.

[0028] In one embodiment of this application, the distributed control system 3 is a DCS system or a PLC control system.

[0029] A boiler system includes a boiler body and a boiler induced draft fan control system of this application. The air outlet of the induced draft fan component 2 of the boiler induced draft fan control system is connected to the flue of the boiler body to achieve energy-saving optimization control of the entire boiler system.

[0030] In the actual operation of this application: the system mainly includes a high-voltage frequency converter 1, an induced draft fan motor 21, an induced draft fan body 22, a blade adjustment actuator 5, and a distributed control system 3. The power input terminal of the high-voltage frequency converter 1 is connected to the plant power supply through a high-voltage cable to obtain working power. The power output terminal of the high-voltage frequency converter 1 is connected to the input terminal of the induced draft fan motor 21 through a power cable to provide the motor with a power supply with variable frequency and voltage, thereby adjusting the speed of the motor.

[0031] The output shaft of the induced draft fan motor 21 is connected to the rotor of the induced draft fan body 22 to provide rotational power for the fan blades of the induced draft fan body 22. The air outlet of the induced draft fan body 22 is connected to the flue inlet of the boiler to extract the flue gas generated by the boiler combustion and maintain the negative pressure in the furnace.

[0032] The blade adjustment actuator 5 is installed at the air outlet of the induced draft fan body 22, and its output rod is mechanically connected to the blade 51 of the induced draft fan body 22. Upon receiving a control signal, the blade adjustment actuator 5 can drive the blade plate 51 to change the blade deflection angle, thereby adjusting the induced draft airflow of the induced draft fan body 22. Figure 3 For example, by controlling the rotation of the moving blade 51 to change the cross-sectional area of ​​the fan blade in the air duct, the size of the air outlet of the air duct can be controlled, thereby controlling the air volume. The mechanical control structure for the rotation of the moving blade 51 is existing technology. For details, please refer to the publicly available information "Principle of Moving Blade Adjustment of Axial Flow Fan", which will not be elaborated here.

[0033] The distributed control system 3 (DCS system) serves as the control core, establishing communication connections with the control terminals of the high-voltage frequency converter 1 and the blade regulating actuator 5 via control circuits. Simultaneously, the DCS system also communicates with various monitoring instruments 4 installed on the boiler via a data bus to collect boiler operating data in real time.

[0034] Based on the workflow shown in the attached diagram, the working principle of this system is as follows: After the system starts up, the distributed control system 3 continuously acquires the boiler's real-time operating parameters from the monitoring instruments 4. These parameters typically include, but are not limited to: furnace negative pressure reflecting the furnace ventilation status, flue gas oxygen content reflecting the degree of combustion completeness, main steam pressure characterizing the boiler load, total air volume, and coal feed rate.

[0035] The furnace negative pressure reflects the balance between induced draft and forced draft, ensuring the safe operation of the boiler and preventing positive pressure flameout or excessive negative pressure. Monitoring instrument 4 is a pressure transmitter or differential pressure transmitter, installed at the upper part of the boiler furnace, used to convert the pressure difference between the furnace interior and atmospheric pressure into a standard electrical signal.

[0036] The oxygen content in the flue gas is measured by using a zirconia sensor located in the tail flue of the boiler. The sensor utilizes the potential generated at high temperatures to measure the oxygen partial pressure in the flue gas.

[0037] Main steam pressure characterizes the balance between the boiler's steam production capacity and external load demand. It is a parameter for judging the boiler load. It is measured by a pressure transmitter installed on the boiler's main steam pipeline. The steam pressure is converted into an electrical signal through an isolation diaphragm and a silicon piezoresistive sensor.

[0038] Total air volume reflects the total amount of air entering the boiler for combustion. It is measured by a flow measurement device at the outlet duct of the blower or the inlet of the air preheater.

[0039] The coal feed rate is measured by a weighing sensor.

[0040] The DCS system has a pre-set algorithm that takes the above-mentioned multiple parameters as input, performs logical judgments, and generates a collaborative control strategy.

[0041] The DCS system sends speed control commands to the control terminal of the high-voltage frequency converter 1 via the control circuit. The frequency converter adjusts the frequency of the output power supply accordingly, thereby precisely controlling the speed of the induced draft fan motor 21. In addition, the DCS system sends opening control commands to the blade adjustment actuator 5, driving the blade 51 at the air outlet of the induced draft fan body 22 to move to the target angle.

[0042] For example, the DCS system is set to a flue gas oxygen content of 3.5% (a preset value, indicating optimal air-to-coal ratio, complete combustion, and minimal flue gas heat loss). When the flue gas oxygen content rises above 3.5%, it indicates that the amount of air entering the furnace (total air volume) is "excessive" relative to the current amount of coal. This leads to increased flue gas heat loss and decreased boiler efficiency. The DCS system generates a command to adjust the high-voltage frequency converter 1, reducing the speed of the induced draft fan motor 21. This reduces the induced draft volume of the induced draft fan body 22, thereby lowering the flue gas oxygen content to the preset value. Simultaneously, the decrease in motor speed, according to the fan law (power is proportional to the cube of speed), reduces motor power consumption. The entire process requires no manual intervention, and the system automatically transitions to a new, highly efficient, and stable state for the motor.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A boiler induced draft fan control system, characterized in that, include: High-voltage frequency converters, induced draft fan assemblies, and distributed control systems; The power input terminal of the high-voltage frequency converter is used to connect to an external power source, and the output terminal of the high-voltage frequency converter is connected to the power input terminal of the induced draft fan assembly via a power cable. The air outlet of the induced draft fan assembly is used to connect to the boiler flue; The distributed control system is connected to the control terminal of the high-voltage frequency converter and communicates with it via a control circuit. The distributed control system is also connected to the boiler's monitoring instruments, which are used to acquire the boiler's real-time operating parameters.

2. The boiler induced draft fan control system according to claim 1, characterized in that, The real-time operating parameters of the boiler include at least one of the following: boiler furnace negative pressure, flue gas oxygen content, main steam pressure, total boiler air volume, and coal feed rate.

3. The boiler induced draft fan control system according to claim 1, characterized in that, The induced draft fan assembly includes an induced draft fan motor and an induced draft fan body, and the output shaft of the induced draft fan motor is connected to the induced draft fan body for transmission.

4. The boiler induced draft fan control system according to claim 3, characterized in that, The moving blades of the induced draft fan body are connected to the moving blade adjustment actuator, and the moving blade adjustment actuator is communicatively connected to the distributed control system.

5. The boiler induced draft fan control system according to claim 4, characterized in that, The blade adjustment actuator is an electric actuator or a hydraulic actuator.

6. The boiler induced draft fan control system according to claim 1, characterized in that, The distributed control system is a DCS system or a PLC control system.

7. A boiler system, characterized in that, The system includes a boiler body and a boiler induced draft fan control system as described in any one of claims 1 to 6, wherein the air outlet of the induced draft fan assembly of the boiler induced draft fan control system is connected to the flue of the boiler body.

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