A pressure control device for a boiler gas pipeline

Abstract

The present invention relates to a pressure control device for a boiler gas pipeline, comprising: an electromagnetic three-way valve, a piezoelectric sensor and a PI controller. The input end of the electromagnetic three-way valve is connected to the upstream gas pipeline. The first output end of the electromagnetic three-way valve is connected to the downstream gas pipeline through a valve, and the piezoelectric sensors are respectively arranged at both ends of the valve for detecting the pressure signals at both ends of the valve. The PI controller is connected to the piezoelectric sensor, performs proportional-integral operation according to the pressure difference at both ends of the valve, and controls the real-time opening degree of the valve. The present invention can effectively improve the response speed and regulation stability of the pressure control of the boiler gas pipeline.

Description

Technical Field

[0001] The present invention relates to the field of mechanical equipment, and particularly to a pressure control device for a boiler gas pipeline. Background Art

[0002] At present, the pressure regulating valve, as an important device for pressure control, is widely used in the pressure control of gas pipelines. The existing pressure control of boiler gas pipelines mainly relies on emergency cut-off valves, pressure regulating valves, check valves to control the flow direction and flow rate of gas, and mainly relies on the pressure regulating valve for pressure control of gas pipelines. When the existing pressure regulating valve is used for pressure control of boiler gas pipelines, due to the mechanical inertia of the components of the pressure regulating valve, there is a problem of slow response speed. When the boiler burner is closed, the pressure regulating valve takes several seconds to fully reach the closed position. During this process, gas will continuously enter the downstream pipeline of the pressure regulating valve, causing the pressure of the downstream pipeline to rise instantaneously, bringing certain potential safety hazards. Moreover, when the boiler increases or decreases the load, the gas pressure fluctuates greatly, and it is difficult to stabilize the pressure through a pressure regulating valve composed of pure mechanical components. Summary of the Invention

[0003] In view of the deficiencies of the prior art, the present invention provides a pressure control device applied to a boiler gas pipeline. When the boiler burner is closed or the pressure of the upstream / downstream gas pipeline fluctuates, through components such as a buffer tank, an electromagnetic three-way valve, and a PI controller in the control device, the response speed and adjustment stability of the pressure control of the boiler gas pipeline are effectively improved.

[0004] To solve at least one of the above technical problems, the technical solution adopted by the present invention is as follows:

[0005] A pressure control device for a boiler gas pipeline includes: an electromagnetic three-way valve, a piezoelectric sensor, and a PI controller. The input end of the electromagnetic three-way valve is connected to the upstream gas pipeline. The first output end of the electromagnetic three-way valve is connected to the downstream gas pipeline through a valve, and piezoelectric sensors are respectively arranged at both ends of the valve to detect the pressure signals at both ends of the valve. The PI controller is connected to the piezoelectric sensor and performs proportional-integral operation according to the pressure difference at both ends of the valve to control the real-time opening of the valve.

[0006] Furthermore, it further includes: a buffer tank and a check valve. The buffer tank is respectively connected to the input end of the electromagnetic three-way valve and the upstream gas pipeline. Both ends of the check valve are respectively connected to the buffer tank and the second output end of the electromagnetic three-way valve to form a gas supply buffer circuit.

[0007] Furthermore, the electromagnetic three-way valve is interlocked with the boiler burner solenoid valve. When the boiler burner solenoid valve is closed, the electromagnetic three-way valve acts simultaneously, closes the first output end and opens the second output end to connect the gas supply buffer circuit.

[0008] Furthermore, the calculation formula for the volume V of the buffer tank is: V≥Q / (7500×k×p), where Q is the designed flow rate of the gas pipeline, p is the outlet pressure of the valve, and k is the pressure coefficient: when p≥0.01MPa, k takes a value of 0.6 - 0.8; when p<0.01MPa, k takes a value of 1.2 - 1.4.

[0009] Furthermore, the signal acquisition frequency of the piezoelectric sensor is 2 - 4 times per second.

[0010] Furthermore, the PI controller includes a PI operation module that performs the proportional-integral operation, where the proportional operation is a non-linear proportion.

[0011] Furthermore, the proportional operation is y P =-(x - Pm) 2 / Pm 2 +1, y P is the control output of the proportional operation, and the integral operation is y I is the control output of the integral operation, and the real-time opening degree y of the valve t =y P +y I , where the x-axis is the actual pressure difference between the front and rear ends of the valve (0≤x≤Pm), the y-axis is the valve opening degree (0≤y≤1), Pm is the maximum pressure difference allowed between the front and rear ends when the valve is working normally, k I is a coefficient and k I takes a value of 8.5 - 13.5, and m in the integral operation is an integer.

[0012] The beneficial effects of the present invention at least include: A pressure control device applied to the gas pipeline of a boiler provided by the present invention is particularly suitable for gas pipelines of boilers with medium and low pressure gas supply, frequent fluctuations in gas supply pressure, or frequent start and stop. It not only provides more stable and accurate pressure control than the existing mechanical pressure regulator, but also can avoid the safety hazard caused by the sudden increase in pressure when gas enters the pipeline downstream of the pressure regulating device when the boiler stops burning. Brief Description of the Drawings

[0013] Figure 1 It is the structural block diagram of the control device of the present invention.

[0014] Figure 2 It is the control characteristic curve of the proportional operation valve opening degree of the present invention.

[0015] Among them, the upstream gas pipeline 1, buffer tank 2, electromagnetic three-way valve 3, check valve 4, valve 5, piezoelectric sensor 6, PI controller 7, boiler burner solenoid valve 8, downstream gas pipeline 9, gas supply buffer circuit 10. Detailed Embodiments

[0016] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below in conjunction with specific embodiments. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as a limitation to the present invention. For those technologies or conditions not specified in the embodiments, they shall be carried out according to the technologies or conditions described in the literature in the field or according to the product specifications.

[0017] Embodiment 1: Figure 1 This is the structural block diagram of the control device of the present invention. Referring to Figure 1 As shown, a pressure control device applied to a boiler gas pipeline provided by the present invention mainly consists of components such as a buffer tank, an electromagnetic three-way valve, a valve, a check valve, a PI controller, two piezoelectric sensors, and a boiler burner solenoid valve. Specifically, its core improvement lies in including a buffer tank, an electromagnetic three-way valve interlocked with the boiler burner solenoid valve, and the electromagnetic three-way bypass is connected to the buffer tank through a check valve. A valve is installed behind the electromagnetic three-way valve, and its opening degree is controlled by a PI controller. The two piezoelectric sensors convert the pressures of the gas pipelines before and after the valve into electrical signals and input them into the PI controller. The PI controller calculates the corresponding valve opening degree and outputs it to the valve, thereby controlling the pressure of the gas pipeline.

[0018] In this embodiment, the volume of the gas pipeline is increased through the buffer tank to reduce the impact on control when the upstream gas supply pressure fluctuates. The electromagnetic three-way valve is interlocked with the boiler burner solenoid valve. When the boiler burner solenoid valve is closed and the boiler stops burning, the electromagnetic three-way valve acts simultaneously, closing the main path and opening the bypass, that is, the gas supply buffer circuit, so that the gas enters the buffer tank through the check valve, avoiding the continuous flow of gas through the valve into the gas pipeline downstream of the valve. A valve is installed behind the electromagnetic three-way valve, and its opening degree is controlled by a PI controller. The two piezoelectric sensors convert the pressures of the gas pipelines before and after the valve into electrical signals and input them into the PI controller. The PI controller performs proportional (P) operation and integral (I) operation on the valve opening degree according to the pressure difference between the two ends of the valve, and converts the operation result into the valve opening degree, thereby controlling the pressure of the gas pipeline, effectively solving the problems existing in the existing pressure regulating valves, such as mechanical inertia, untimely action, and great difficulty in controlling the gas pipeline pressure when the gas pressure fluctuates greatly.

[0019] In order to more effectively and accurately control the pressure of the gas pipeline, the present application makes the following design: Ensure that the buffer tank is installed in the upstream gas pipeline of the entire control device. The calculation formula for the volume V of the buffer tank is: V≥Q / (7500×k×p), where Q is the designed flow rate of the gas pipeline, p is the outlet pressure of the valve, and k is the pressure coefficient: when p≥0.01MPa, k takes 0.6 - 0.8; when p<0.01MPa, k takes 1.2 - 1.4. The signal acquisition frequency of the piezoelectric sensor is 2 - 4 times per second.

[0020] The PI controller includes a PI operation module that performs the proportional-integral operation. Among them, the proportional operation is a non-linear proportion, and its valve control characteristic curve is as Figure 2 shown.

[0021] More specifically: The mathematical expression of the proportional operation valve control characteristic curve is y P = -(x - Pm) 2 / Pm 2 + 1, where y P is the control output of the proportional (P) operation; the mathematical expression of the integral operation is y I is the control output of the integral (I) operation. The real-time opening degree y of the valve t = y P + y I . The PI controller controls the valve opening degree to control the pressure of the gas pipeline. Among them, the x-axis is the actual pressure difference between the front and rear ends of the valve (0 ≤ x ≤ Pm), the y-axis is the valve opening degree (0 ≤ y ≤ 1), Pm is the maximum pressure difference allowed between the front and rear ends when the valve is working normally, k I is a coefficient and k I takes 8.5 - 13.5, and m in the integral operation formula is an integer.

[0022] In summary, a pressure control device for a boiler gas pipeline provided by the present invention is particularly suitable for gas pipelines of boilers with medium and low pressure supply, frequent fluctuations in supply pressure, or frequent start and stop. It not only provides more stable and accurate pressure control than existing mechanical pressure regulators, but also can avoid the safety hazards caused by the sudden increase in pressure due to gas entering the downstream pipeline of the pressure regulating device when the boiler stops burning.

[0023] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention. At the same time, for those of ordinary skill in the art, according to the idea of this application, there will be changes in the specific implementation manner and application scope.

Claims

1. A pressure control device for a boiler gas pipeline, characterized in that, Including: An electromagnetic three-way valve, a piezoelectric sensor and a PI controller. The input end of the electromagnetic three-way valve is connected to the upstream gas pipeline. The first output end of the electromagnetic three-way valve is connected to the downstream gas pipeline through a valve, and the piezoelectric sensors are respectively arranged at both ends of the valve to detect the pressure signals at both ends of the valve. The PI controller is connected to the piezoelectric sensor and performs proportional-integral operation according to the pressure difference at both ends of the valve to control the real-time opening of the valve; It further includes: a buffer tank and a check valve. The buffer tank is respectively connected to the input end of the electromagnetic three-way valve and the upstream gas pipeline. Both ends of the check valve are respectively connected to the buffer tank and the second output end of the electromagnetic three-way valve to form a gas supply buffer circuit. The electromagnetic three-way valve is interlocked with the boiler burner solenoid valve. When the boiler burner solenoid valve is closed, the electromagnetic three-way valve acts simultaneously, closes the first output end and opens the second output end to connect the gas supply buffer circuit; The calculation formula for the volume V of the buffer tank is: V≥Q / (7500×k×p), where Q is the designed flow rate of the gas pipeline, p is the outlet pressure of the valve, and k is the pressure coefficient: when p≥0.01MPa, k takes 0.6 - 0.8; when p<0.01MPa, k takes 1.2 - 1.4; The proportional operation is yp = -(x - Pm) 2 / Pm 2 + 1, where yp is the output of the proportional operation control, and the integral operation is , is the output of the integral operation control, and the real-time opening of the valve , where the x-axis is the actual pressure difference between the front and rear ends of the valve (0 ≤ x ≤ Pm), the y-axis is the valve opening (0 ≤ y ≤ 1), and Pm is the maximum pressure difference allowed between the front and rear ends when the valve is working normally. is a coefficient and takes 8.5 - 13.5, and m in the integral operation is an integer.

2. The pressure control device according to claim 1, characterized in that, The signal acquisition frequency of the piezoelectric sensor is 2 - 4 times per second.

3. The pressure control device according to claim 1, characterized in that The PI controller includes a PI operation module, which performs the proportional-integral operation, wherein the proportional operation is a non-linear proportion.

Images