A primary and secondary air connection pulverized coal furnace air supply system

Abstract

The utility model provides a primary and secondary air intercommunication's pulverized coal furnace air supply system, including primary and secondary air intercommunication pipe, booster fan and electric regulation baffle, the inlet end of primary and secondary air intercommunication pipe is connected in secondary hot air flue, its export is connected in primary hot air flue, forms the intercommunication path of secondary hot air to primary hot air flue, along the flow direction of secondary hot air in primary and secondary air intercommunication pipe, is provided with booster fan and electric regulation baffle in proper order, booster fan is used for lifting the pressure of secondary hot air, electric regulation baffle is used for accurately adjusting the size of intercommunication air quantity, the utility model's effect lies in: establishes an accurate regulation and control's, from secondary hot air flue to primary hot air flue's temperature regulation channel, through opening the valve on intercommunication pipeline and starting booster fan, directly and effectively compensates the air quantity and heat gap of primary air, makes the boiler combustion to be in the state of key parameter recovery normal under the continuous stable operation of stable operation.

Description

Technical Field

[0001] This utility model relates to the field of pulverized coal furnace technology, specifically to a pulverized coal furnace air supply system that connects primary and secondary air. Background Technology

[0002] Pulverized coal boilers are core equipment in modern thermal power plants, and their combustion efficiency and stability directly affect the plant's economy and safety. In pulverized coal boilers, the primary air's main function is to transport and dry the pulverized coal and provide some oxygen for initial ignition. The temperature and volume of the primary air are key parameters for ensuring stable combustion of pulverized coal. Too low a temperature will lead to difficulty in igniting the pulverized coal, unstable combustion, and decreased efficiency; insufficient air volume may cause blockages in the pulverized coal conveying pipes, uneven combustion within the furnace, and even fire extinguishing or other safety accidents.

[0003] Primary air is typically delivered by a primary air fan and heated by an air preheater to become hot primary air. In actual operation, especially when burning high-sulfur, high-ash coal, the low-temperature section of the air preheater is prone to ammonium bisulfate condensation and ash blockage. This blockage is often asymmetrical, leading to significant deviations in primary air volume and temperature on both sides of the boiler. Traditional solutions involve shutting down the boiler for steam soot blowing or high-pressure water flushing. This not only causes unplanned unit shutdowns and substantial economic losses but also only addresses the symptoms, not the root cause, resulting in recurring blockage problems.

[0004] Therefore, there is an urgent need for a technical solution that can compensate for the primary air volume and temperature on the air preheater side due to blockage without shutting down the boiler, so as to ensure the safe, stable and efficient operation of the boiler. Utility Model Content

[0005] To address the shortcomings of existing technologies, this utility model aims to solve the problem of low primary air temperature and insufficient air volume in pulverized coal boilers during operation due to blockage of the unilateral air preheater. It provides a primary and secondary air interconnection air supply system for pulverized coal boilers, including a primary and secondary air interconnection pipe, a booster fan, and an electrically adjustable baffle. The inlet end of the primary and secondary air interconnection pipe is connected to the secondary hot air duct, and its outlet end is connected to the primary hot air duct, forming an interconnection path between the secondary and primary hot air ducts. Along the flow direction of the secondary hot air within the primary and secondary air interconnection pipe, the booster fan and the electrically adjustable baffle are sequentially arranged. The booster fan is used to increase the pressure of the secondary hot air, and the electrically adjustable baffle is used to precisely adjust the interconnection air volume. The primary and secondary air interconnection pipe is also equipped with a pressure transmitter, a temperature detection element, and a flow meter for monitoring duct parameters. The signal output terminals of each detection element are electrically connected to a DCS control system, and the control signal output terminal of the DCS control system is connected to the electrically adjustable baffle, adjusting its opening degree in real time according to the monitored parameters.

[0006] As a preferred embodiment, a check valve is provided on the primary and secondary air connecting pipe. The check valve adopts a swing-type structure and is installed on the outlet pipe section of the booster fan. Its installation direction is set to allow secondary hot air to flow into the primary hot air duct, preventing backflow of the medium.

[0007] As a preferred embodiment, the electrically adjustable baffle adopts a louvered structure design and is equipped with an electric actuator, which can work in conjunction with the pressure transmitter, temperature detection element and flow meter to form a closed-loop control system for precise airflow regulation.

[0008] As a preferred embodiment, the pressure transmitter, temperature sensing element, and flow meter are installed in the outlet pipe of the booster fan and transmitted to the DCS control system via a 4–20mA signal.

[0009] As a preferred solution, the DCS control system receives signals from the pressure transmitter, temperature sensing element and flow meter through the PID algorithm, calculates and outputs the opening command of the electric regulating baffle, so that the parameters of the secondary hot air incorporated into the primary hot air duct are stabilized within the target value range to form a closed-loop control.

[0010] As a preferred embodiment, the primary and secondary air connecting pipe adopts a tapered pipe structure to optimize the mixing effect of secondary hot air and primary hot air and reduce flow resistance.

[0011] As a preferred embodiment, the electrically adjustable baffle is equipped with a handwheel mechanism for manually adjusting the opening degree, enabling manual control of the system in emergency situations.

[0012] As a preferred embodiment, the pressure transmitter, temperature sensing element, and flow meter are equipped with alarm devices to issue an alarm when the pressure, temperature, or flow parameters exceed the set range.

[0013] Compared with the prior art, the present invention has the following advantages: 1. This utility model establishes a precisely adjustable temperature control channel from the secondary hot air duct to the primary hot air duct. By opening the valves on the connecting pipeline and starting the booster fan, the air volume and heat gap of the primary air are directly and effectively compensated, so that the boiler combustion can continue to operate stably when the key parameters are restored to normal. This avoids the huge production interruption losses caused by the need to immediately shut down the boiler for maintenance due to blockage. It realizes online processing without shutting down the boiler, effectively avoiding the power generation loss and economic loss caused by shutting down the boiler to clean the air preheater.

[0014] 2. This utility model adopts a closed-loop control strategy. The system can automatically adjust according to real-time monitored parameters, with fast response speed and high control accuracy, reducing the operational burden on operators. By ensuring stable boiler combustion, it improves boiler efficiency and reduces various costs caused by poor combustion and unplanned shutdowns. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of this utility model.

[0016] In the diagram: 1. Primary and secondary air connecting pipe; 2. Front gate valve; 3. Booster fan; 4. Electric regulating baffle; 5. Check valve; 6. Rear gate valve; 7. Pressure transmitter; 8. Temperature sensing element; 9. Flow meter; 10. Primary hot air duct; 11. Secondary hot air duct. Detailed Implementation

[0017] The following is in conjunction with the appendix Figure 1 The present invention will be further described in detail below with reference to specific embodiments.

[0018] Example 1: like Figure 1 As shown in the figure, this embodiment of the present invention provides a pulverized coal boiler air supply system with primary and secondary air interconnection, and the specific structure is described as follows: The system includes a primary and secondary air connecting pipe 1, a booster fan 3, and an electrically adjustable baffle 4. The primary and secondary air connecting pipe 1 adopts a tapered pipe structure, with its inlet end connected to the secondary hot air duct 11 and its outlet end connected to the primary hot air duct 10, forming a connecting path with a diameter that gradually decreases from 800 mm to 600 mm. Along the flow direction of the secondary hot air in the pipe, a front gate valve 2, a booster fan 3, a check valve 5, an electrically adjustable baffle 4, and a rear gate valve 6 are sequentially installed.

[0019] The booster fan 3 is a centrifugal fan with a rated air volume of 50,000 cubic meters per hour and a total pressure boosting capacity of 3,000 kPa, used to increase the secondary hot air pressure to a level matching the primary hot air pressure. The electrically adjustable damper 4 adopts a louvered structure and is equipped with an electric actuator, with an adjustment time of fifteen seconds, enabling opening adjustment from 0 to 90 degrees. This damper also has a handwheel mechanism for manual operation in emergencies.

[0020] Check valve 5, a DN600 swing valve, is installed on the outlet pipe section of booster fan 3 to effectively prevent backflow of the medium. A pressure transmitter 7, a temperature sensing element 8, and a flow meter 9 are installed on the booster fan outlet pipe. The pressure transmitter 7 has a range of 0 to 10 kPa, the temperature sensing element 8 has a range of 0 to 400 degrees Celsius, and the flow meter 9 is a vortex flow meter with a range of 0 to 60,000 cubic meters per hour. Each sensing element transmits monitoring data to the DCS control system via a 4 to 20 mA signal.

[0021] The DCS control system receives monitoring signals through a PID algorithm. When pressure, temperature, or flow parameters exceed the set range, the system will issue an audible and visual alarm. Based on preset control logic, the control system calculates the optimal opening command for the electrically adjustable damper 4, forming a complete closed-loop control. The target control parameters are set as follows: airflow of 45,000 cubic meters per hour, temperature of 350 degrees Celsius, and pressure of 8.5 kPa.

[0022] This system effectively solves the problem of insufficient primary air volume and temperature caused by blockage of the air preheater or denitrification catalyst by precisely controlling the parameters of secondary hot air integration into the primary air duct. The entire system adopts automated control, operates stably and reliably, and ensures the safe and efficient operation of the pulverized coal boiler.

[0023] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A pulverized coal boiler air supply system with primary and secondary air interconnection, characterized in that, The system includes a primary and secondary air connecting pipe (1), a booster fan (3), and an electric regulating baffle (4). The inlet end of the primary and secondary air connecting pipe (1) is connected to the secondary hot air duct (11), and its outlet end is connected to the primary hot air duct (10), forming a connecting path from the secondary hot air to the primary hot air duct (10). Along the flow direction of the secondary hot air in the primary and secondary air connecting pipe (1), the booster fan (3) and the electric regulating baffle (4) are arranged in sequence. The booster fan (3) is used to increase the pressure of the secondary hot air, and the electric regulating baffle (4) is used to precisely adjust the size of the connecting air volume. The primary and secondary air connecting pipe (1) is also equipped with a pressure transmitter (7), a temperature detection element (8), and a flow meter (9) for monitoring duct parameters. The signal output terminals of each detection element are electrically connected to the DCS control system, and the control signal output terminal of the DCS control system is connected to the electric regulating baffle (4) to adjust its opening degree in real time according to the monitoring parameters.

2. The pulverized coal boiler air supply system with primary and secondary air interconnection according to claim 1, characterized in that, The primary and secondary air connecting pipe (1) is equipped with a check valve (5). The check valve (5) adopts a swing type structure and is installed on the outlet pipe section of the booster fan (3). Its installation direction is set to allow the secondary hot air to flow to the primary hot air duct (10) to prevent the medium from flowing back.

3. The pulverized coal boiler air supply system with primary and secondary air interconnection according to claim 1, characterized in that, The electric regulating baffle (4) adopts a louvered structure design and is equipped with an electric actuator. It can work together with the pressure transmitter (7), temperature detection element (8) and flow meter (9) to form a closed-loop control system to accurately regulate the air volume.

4. The pulverized coal boiler air supply system with primary and secondary air interconnection according to claim 1, characterized in that, The pressure transmitter (7), temperature sensing element (8), and flow meter (9) are installed on the outlet pipe of the booster fan and transmitted to the DCS control system via a 4–20mA signal.

5. The pulverized coal boiler air supply system with primary and secondary air interconnection according to claim 1 or 4, characterized in that, The DCS control system receives signals from the pressure transmitter, temperature detection element and flow meter through the PID algorithm, calculates and outputs the opening command of the electric regulating baffle, so that the parameters of the secondary hot air incorporated into the primary hot air duct (10) are stabilized within the target value range to form a closed loop control.

6. The pulverized coal boiler air supply system with primary and secondary air interconnection according to claim 1, characterized in that, The primary and secondary air connecting pipe (1) adopts a tapered pipe structure to optimize the mixing effect of secondary hot air and primary hot air and reduce flow resistance.

7. The pulverized coal boiler air supply system with primary and secondary air interconnection according to claim 1, characterized in that, The electric adjustment baffle (4) is equipped with a handwheel mechanism for manually adjusting the opening degree, so as to realize manual control in emergency situations.

8. The pulverized coal boiler air supply system with primary and secondary air interconnection according to claim 1, characterized in that, The pressure transmitter (7), temperature sensing element (8), and flow meter (9) are equipped with alarm devices to issue an alarm when the pressure, temperature, or flow parameters exceed the set range.

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