Emptying control device for low-pressure steam drum deaerator of gas-fired boiler

Abstract

The invention relates to the technical field of gas-fired boiler steam drums, and discloses a gas-fired boiler low-pressure steam drum deaerator emptying control device which comprises two oxygen content monitoring devices, namely a first oxygen content monitoring device and a second oxygen content monitoring device, the first oxygen content monitoring device is installed at an outlet of a deaerator emptying pipeline, and the second oxygen content monitoring device is installed at an outlet of a deaerator emptying pipeline. The second oxygen content monitoring device is mounted at an inlet of an emptying pipeline of the deaerator; the control device further comprises a flow monitoring device installed in the emptying pipeline of the deaerator, an emptying door opening adjusting device installed on the emptying door and a controller. The controller receives numerical values measured by the first oxygen content monitoring device, the second oxygen content monitoring device and the flow monitoring device, calculates the numerical values and then controls the emptying door opening degree adjusting device to adjust the opening degree of the emptying door in real time; according to the method, the opening degree of the emptying door is adjusted in real time by combining actual parameter conditions in the emptying pipeline, and the method has the advantages that the emptying amount is set more accurately and reasonably, unnecessary emission is reduced, and resources are saved.

Description

Technical Field

[0001] This invention relates to a deaerator venting control device for a low-pressure steam drum of a gas-fired boiler, belonging to the technical field of gas-fired boiler steam drums. Background Technology

[0002] A gas-fired boiler is a boiler that uses gaseous fuels such as natural gas, liquefied petroleum gas, or town gas as its energy source. It injects gas into the boiler's furnace through a burner, where it mixes thoroughly with air and burns, releasing a large amount of heat energy. This heat energy is used to heat the water inside the boiler, turning it into steam or hot water to meet various industrial production or domestic needs.

[0003] When a gas-fired boiler is in operation, dissolved oxygen in the water is a strong oxidant. If left untreated, this oxygen can easily cause corrosion and other problems, affecting the boiler's thermal efficiency and the quality of the steam produced. Therefore, a deaerator is necessary to remove oxygen from the gas-fired boiler. Most existing gas-fired boiler deaerators use thermal deaeration devices. The principle of thermal deaeration is mainly based on the Dalton-Henry principle, where low-pressure steam drum feedwater discharges oxygen and other gases through the deaerator's vent valve. Currently, the deaerator vent valve opening is mainly controlled manually by the operator. This means the venting volume is controlled by the operator's experience, which can easily lead to inaccurate venting control. Problems include excessively large vent openings resulting in steam waste, and insufficient vent openings failing to achieve the desired effect.

[0004] To address this, in the prior art, Chinese utility model patent application number CN202323583274.1 discloses a deaerator-based exhaust system. This system uses a regulating valve on the exhaust pipe to adjust the steam output, thereby regulating the exhaust valve and the exhaust pipe opening. Based on the flow meter's display status, different valve openings can be adjusted according to the actual exhaust volume under different operating conditions, achieving precise control of different exhaust volumes and solving the problem of inaccurate exhaust volume control in existing technologies. However, in practical use, it still has the following problems: Although it can precisely control the venting volume, the determination of its venting volume value is still based on the operator's experience, without taking into account the actual parameters inside the exhaust pipe, resulting in an unreasonable venting volume setting. Summary of the Invention

[0005] In order to solve the above-mentioned problems existing in the prior art, the present invention provides a gas boiler low-pressure steam drum deaerator venting control device.

[0006] The technical solution of the present invention is as follows: A deaerator venting control device for a low-pressure steam drum of a gas-fired boiler includes two oxygen content monitoring devices: a first oxygen content monitoring device and a second oxygen content monitoring device. The first oxygen content monitoring device is installed at the outlet of the deaerator venting pipe to monitor the oxygen content of the gas discharged from the deaerator venting pipe. The second oxygen content monitoring device is installed at the inlet of the deaerator venting pipe to monitor the oxygen content of the gas entering the deaerator venting pipe. The control device also includes a flow monitoring device installed inside the deaerator venting pipe to monitor the gas flow rate, a venting valve opening adjustment device installed on the venting valve to adjust the venting valve opening, and a controller. The controller receives the values ​​measured by the first oxygen content monitoring device, the second oxygen content monitoring device, and the flow monitoring device, calculates the values, and then controls the venting valve opening adjustment device to adjust the venting valve opening in real time.

[0007] Furthermore, the oxygen content monitoring device includes The sampling module is used to collect gas samples from the deaerator vent pipe. The preprocessing module is used to preprocess the gas samples collected by the sampling module; The detection module is used to detect the oxygen content of the gas sample after it has been preprocessed by the preprocessing module and output an electrical signal. The signal processing and transmission module is used to process the electrical signals output by the detection module, convert them into digital signals, and then transmit them to the controller.

[0008] Furthermore, the flow monitoring device includes The flow sensing module is used to detect the gas flow rate in the deaerator venting pipe and output an electrical signal. The signal processing module is used to process the electrical signal output by the flow sensing module and convert it into a digital signal; The communication module is used to transmit the digital signals converted by the signal processing module to the controller.

[0009] Furthermore, the controller uses the following method to control the vent door opening adjustment device to adjust the vent door opening in real time: Obtain the oxygen content of the gas discharged from the deaerator exhaust pipe, obtain the oxygen content of the gas entering the deaerator exhaust pipe, obtain the initial oxygen content of the gas in the deaerator exhaust pipe before the exhaust valve is opened, and obtain the gas flow rate in the deaerator exhaust pipe. The following formula is used for calculation:

[0010] In the formula, C represents the oxygen content of the gas discharged from the deaerator exhaust pipe, C0 represents the initial oxygen content of the gas in the deaerator exhaust pipe before the exhaust valve is opened, x represents the opening degree of the exhaust valve, 0≤x≤1, 0 represents fully closed, 1 represents fully open, Q(x) represents the gas flow rate in the deaerator exhaust pipe when the exhaust valve opening degree is x, and Q max C1 represents the gas flow rate when the vent valve is at its maximum opening, C1 represents the oxygen content of the gas entering the deaerator vent pipe, and m represents the mixing index.

[0011] Furthermore, the method for obtaining C0 is as follows: Before the vent door is opened, take the average value of the value measured by the first oxygen content monitoring device and the value measured by the second oxygen content monitoring device.

[0012] Furthermore, the method for obtaining m is as follows: The following formula is used for calculation:

[0013] In the formula, m represents the mixing index, k represents the correction coefficient, L represents the length of the deaerator vent pipe, d represents the diameter of the deaerator vent pipe, D represents the gas diffusion coefficient, and v(x) represents the gas velocity in the deaerator vent pipe when the vent valve opening is x.

[0014] Furthermore, the method for obtaining k is as follows: If the deaerator vent pipe is a straight pipe, k is taken as 0.1 to 0.5; If the deaerator vent pipe is a bend, k should be 0.5 to 1.5.

[0015] Furthermore, v(x) is obtained as follows: The following formula is used for calculation:

[0016] In the formula, Q(x) represents the gas flow rate in the deaerator vent pipe when the vent valve opening is x, and A represents the cross-sectional area of ​​the deaerator vent pipe.

[0017] Furthermore, the detection module is selected as a zirconium oxide oxygen sensor.

[0018] Furthermore, the flow sensing module is selected as an ultrasonic gas flow meter.

[0019] The present invention has the following beneficial effects: This invention incorporates two oxygen content monitoring devices, a flow rate monitoring device, a controller, and an exhaust valve opening adjustment device. The oxygen content monitoring devices monitor the oxygen content of the gas in the deaerator exhaust pipe in real time, and the flow rate monitoring devices monitor the flow rate of the gas in the deaerator exhaust pipe in real time. The controller, by acquiring the values ​​from the two oxygen content and flow rate monitoring devices, controls the exhaust valve opening adjustment device according to its own pre-set program, allowing for real-time adjustment of the exhaust valve opening. Compared to traditional methods that rely on human experience to set the exhaust volume, this invention combines the actual parameters within the exhaust pipe to adjust the exhaust valve opening in real time. This enables intelligent real-time adjustment of the exhaust volume, allowing it to flexibly change according to the actual parameters within the exhaust pipe, rather than remaining constant. This results in more accurate and reasonable exhaust volume setting, reduced unnecessary emissions, and resource conservation. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the module composition of the present invention; Figure 2 This is a schematic diagram of the module composition of the oxygen content monitoring device in this invention; Figure 3 This is a schematic diagram of the module composition of the flow monitoring device in this invention.

[0021] The reference numerals in the figure are as follows: 1. First oxygen content monitoring device; 2. Second oxygen content monitoring device; 3. Flow monitoring device; 4. Exhaust valve opening adjustment device; 5. Controller; 6. Sampling module; 7. Preprocessing module; 8. Detection module; 9. Signal processing and transmission module; 10. Flow sensing module; 11. Signal processing module; 12. Communication module. Detailed Implementation

[0022] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0023] Example: Please refer to Figures 1-3 This embodiment provides a deaerator venting control device for a low-pressure steam drum of a gas-fired boiler, including two oxygen content monitoring devices, namely a first oxygen content monitoring device 1 and a second oxygen content monitoring device 2. The first oxygen content monitoring device 1 is installed at the outlet of the deaerator venting pipe and is used to monitor the oxygen content of the gas discharged from the deaerator venting pipe. The second oxygen content monitoring device 2 is installed at the inlet of the deaerator venting pipe and is used to monitor the oxygen content of the gas entering the deaerator venting pipe.

[0024] In this embodiment, both oxygen content monitoring devices, namely the first oxygen content monitoring device 1 and the second oxygen content monitoring device 2, include a sampling module 6 for collecting gas samples from the deaerator exhaust pipe, a preprocessing module 7 for preprocessing the gas samples collected by the sampling module 6, a detection module 8 for detecting the oxygen content of the gas samples preprocessed by the preprocessing module 7 and outputting an electrical signal, and a signal processing and transmission module 9 for processing the electrical signal output by the detection module 8, converting it into a digital signal, and transmitting it.

[0025] The sampling module 6 transports the collected gas to the subsequent preprocessing module 7 for preprocessing.

[0026] The preprocessing module 7 can specifically dry the received gas sample (by setting a drying bag) and filter it (by setting a filter) to remove moisture, impurities and particulate matter from the gas, thereby preventing them from affecting the detection results of the subsequent detection module 8.

[0027] Detection module 8 is selected as a zirconia oxygen sensor. The zirconia oxygen sensor utilizes the oxygen ion conduction characteristics of zirconia at high temperatures. In a high-temperature environment, the difference in oxygen concentration on both sides of the zirconia will generate a potential difference, which can be measured to determine the oxygen concentration. Zirconia oxygen sensors have the advantages of good stability and long service life, but require high operating temperatures. Since the venting pipeline is precisely a high-temperature environment, the selection of a zirconia oxygen sensor for detection module 8 is very suitable.

[0028] Specifically, the signal processing and transmission module 9 can amplify (by setting a signal amplification circuit), filter (by setting a filtering circuit), and digitize (by setting an A / D conversion module) the electrical signal output by the detection module 8, and then transmit the generated digital signal through a communication connection.

[0029] The deaerator venting control device also includes a flow monitoring device 3 installed in the deaerator venting pipe to monitor the gas flow rate in the deaerator venting pipe, a venting door opening adjustment device 4 installed on the venting door to adjust the venting door opening, and a controller 5.

[0030] The flow monitoring device 3 includes a flow sensing module 10 for detecting the gas flow rate in the deaerator venting pipe and outputting an electrical signal, a signal processing module 11 for processing the electrical signal output by the flow sensing module 10 and converting it into a digital signal, and a communication module 12 for transmitting the digital signal converted by the signal processing module 11.

[0031] The flow sensing module 10 is selected as an ultrasonic gas flow meter. Ultrasonic gas flow meters measure gas flow by utilizing the principle that the difference in propagation time of ultrasonic waves in a gas between upstream and downstream directions is related to the gas flow velocity. It has the advantages of not directly contacting the gas, not interfering with gas flow, and not being affected by gas corrosion or abrasion, thus ensuring accurate detection results.

[0032] Specifically, the signal processing module 11 can amplify (by setting a signal amplification circuit), filter (by setting a filtering circuit), and digitize (by setting an A / D conversion module) the electrical signal output by the flow sensing module 10.

[0033] Specifically, the communication module can transmit the digital signals generated by the signal processing module 11 through a communication connection.

[0034] The venting door opening adjustment device 4 can be an electric actuator. It is installed on the venting door and uses electricity as a power source. In conjunction with the electric motor driving the reduction mechanism, the rotational motion of the motor is converted into linear motion or angular displacement, thereby driving the venting door to open or close.

[0035] The controller 5 can be installed outside the deaerator vent pipe and connected wirelessly to the first oxygen content monitoring device 1, the second oxygen content monitoring device 2, the flow monitoring device 3, and the vent valve opening adjustment device 4. The signal processing and transmission modules 9 in the first oxygen content monitoring device 1 and the second oxygen content monitoring device 2 transmit the generated digital signals to the controller 5. The communication module 12 in the flow detection device transmits the digital signals generated by the signal processing module 11 to the controller 5. The controller 5 receives the values ​​measured by the first oxygen content monitoring device 1, the second oxygen content monitoring device 2, and the flow monitoring device 3, calculates the values, and controls the vent valve opening adjustment device 4 to adjust the vent valve opening in real time.

[0036] Through the aforementioned settings, this embodiment adjusts the vent valve opening in real time by incorporating actual parameters within the vent pipe, thereby enabling intelligent real-time adjustment of the venting volume. This allows the venting volume to flexibly change according to the actual parameters within the vent pipe, rather than remaining constant. On one hand, this ensures the oxygen content of the low-pressure steam drum feedwater is controlled within the specified range; on the other hand, it reduces unnecessary emissions and saves resources, making it worthy of promotion.

[0037] In this embodiment, the controller 5 uses the following method to control the vent door opening adjustment device 4 to adjust the vent door opening in real time: Obtain the oxygen content of the gas discharged from the deaerator exhaust pipe, obtain the oxygen content of the gas entering the deaerator exhaust pipe, obtain the initial oxygen content of the gas in the deaerator exhaust pipe before the exhaust valve is opened, and obtain the gas flow rate in the deaerator exhaust pipe. The following formula is used for calculation:

[0038] In the formula, C represents the oxygen content of the gas discharged from the deaerator vent pipe, measured by the first oxygen content monitoring device 1; C0 represents the initial oxygen content of the gas in the deaerator vent pipe before the vent valve is opened. C0 is obtained by taking the average value of the value measured by the first oxygen content monitoring device 1 and the value measured by the second oxygen content monitoring device 2 before the vent valve is opened. This average value is the initial oxygen content of the gas in the deaerator vent pipe before the vent valve is opened. Multiple measurements and calculations can be performed to obtain the average value to improve accuracy. x represents the vent valve opening degree, 0≤x≤1, 0 represents fully closed, and 1 represents fully open; Q(x) represents the gas flow rate in the deaerator vent pipe when the vent valve opening degree is x, measured by the flow monitoring module; Q max The flow rate is measured by the flow monitoring module when the vent valve is at its maximum opening. C1 represents the oxygen content of the gas entering the deaerator vent pipe, measured by the second oxygen content monitoring device 2. m represents the mixing index, which reflects the uniformity and speed of mixing between the newly entering gas and the existing gas in the deaerator vent pipe. m can be obtained in several ways, including experimental determination, formula calculation, or empirical setting.

[0039] In this embodiment, m is obtained as follows: The following formula is used for calculation:

[0040] In the formula, m represents the mixing index, k represents the correction coefficient, and k is obtained as follows: if the deaerator exhaust pipe is a straight pipe, k is 0.1 to 0.5; if the deaerator exhaust pipe is a bend, k is 0.5 to 1.5. L represents the length of the deaerator exhaust pipe, which is obtained by actual measurement of the deaerator exhaust pipe or by referring to the deaerator exhaust pipe's production manual. d represents the diameter of the deaerator exhaust pipe, which is obtained by actual measurement of the deaerator exhaust pipe or by referring to the deaerator exhaust pipe's production manual. D represents the gas diffusion coefficient, which is obtained by consulting relevant manuals, such as chemical and chemical engineering property data manuals. When consulting these manuals, data close to the actual operating conditions should be selected. v(x) represents the gas velocity in the deaerator exhaust pipe when the exhaust valve opening is x. v(x) is obtained as follows: The following formula is used for calculation:

[0041] In the formula, Q(x) represents the gas flow rate in the deaerator vent pipe when the vent valve opening is x, which is measured by the flow monitoring module; A represents the cross-sectional area of ​​the deaerator vent pipe, which is obtained from the deaerator vent pipe production manual or by formula. The calculation is performed using d, which represents the diameter of the deaerator vent pipe. This diameter is obtained by actually measuring the deaerator vent pipe or by referring to the deaerator vent pipe's production manual.

[0042] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A gas boiler low-pressure steam drum deaerator venting control device, characterized in that: The device includes two oxygen content monitoring devices, namely a first oxygen content monitoring device (1) and a second oxygen content monitoring device (2). The first oxygen content monitoring device (1) is installed at the outlet of the deaerator exhaust pipe to monitor the oxygen content of the gas discharged from the deaerator exhaust pipe. The second oxygen content monitoring device (2) is installed at the inlet of the deaerator exhaust pipe to monitor the oxygen content of the gas entering the deaerator exhaust pipe. The control device also includes a flow monitoring device (3) installed in the deaerator exhaust pipe to monitor the gas flow rate in the deaerator exhaust pipe, an exhaust door opening adjustment device (4) installed on the exhaust door to adjust the opening of the exhaust door, and a controller (5). The controller (5) receives the values ​​measured by the first oxygen content monitoring device (1), the second oxygen content monitoring device (2), and the flow monitoring device (3), calculates them, and controls the exhaust door opening adjustment device (4) to adjust the opening of the exhaust door in real time.

2. The exhaust control device for a low-pressure steam drum deaerator of a gas-fired boiler according to claim 1, characterized in that: The oxygen content monitoring device includes The sampling module (6) is used to collect gas samples from the deaerator vent pipe; The preprocessing module (7) is used to preprocess the gas samples collected by the sampling module (6); The detection module (8) is used to detect the oxygen content of the gas sample after preprocessing by the preprocessing module (7) and output an electrical signal. The signal processing and transmission module (9) is used to process the electrical signal output by the detection module (8) and convert it into a digital signal before transmitting it to the controller (5).

3. The exhaust control device for a low-pressure steam drum deaerator of a gas-fired boiler according to claim 1, characterized in that: The flow monitoring device (3) includes The flow sensing module (10) is used to detect the gas flow rate in the deaerator exhaust pipe and output an electrical signal; The signal processing module (11) is used to process the electrical signal output by the flow sensing module (10) and convert it into a digital signal; The communication module (12) is used to transmit the digital signal converted by the signal processing module (11) to the controller (5).

4. The exhaust control device for a low-pressure steam drum deaerator of a gas-fired boiler according to claim 1, characterized in that: The controller (5) uses the following method to control the vent door opening adjustment device (4) to adjust the vent door opening in real time: Obtain the oxygen content of the gas discharged from the deaerator exhaust pipe, obtain the oxygen content of the gas entering the deaerator exhaust pipe, obtain the initial oxygen content of the gas in the deaerator exhaust pipe before the exhaust valve is opened, and obtain the gas flow rate in the deaerator exhaust pipe. The following formula is used for calculation: In the formula, C represents the oxygen content of the gas discharged from the deaerator exhaust pipe, C0 represents the initial oxygen content of the gas in the deaerator exhaust pipe before the exhaust valve is opened, x represents the opening degree of the exhaust valve, 0≤x≤1, 0 represents fully closed, 1 represents fully open, Q(x) represents the gas flow rate in the deaerator exhaust pipe when the exhaust valve opening degree is x, and Q max C1 represents the gas flow rate when the vent valve is at its maximum opening, C1 represents the oxygen content of the gas entering the deaerator vent pipe, and m represents the mixing index.

5. The exhaust control device for a low-pressure steam drum deaerator of a gas-fired boiler according to claim 4, characterized in that: The method for obtaining C0 is as follows: Before the vent door is opened, take the average value of the value measured by the first oxygen content monitoring device (1) and the value measured by the second oxygen content monitoring device (2).

6. The exhaust control device for a low-pressure steam drum deaerator of a gas-fired boiler according to claim 4, characterized in that: The method for obtaining m is as follows: The following formula is used for calculation: In the formula, m represents the mixing index, k represents the correction coefficient, L represents the length of the deaerator vent pipe, d represents the diameter of the deaerator vent pipe, D represents the gas diffusion coefficient, and v(x) represents the gas velocity in the deaerator vent pipe when the vent valve opening is x.

7. The exhaust control device for a low-pressure steam drum deaerator of a gas-fired boiler according to claim 6, characterized in that: The method for obtaining k is as follows: If the deaerator vent pipe is a straight pipe, k is taken as 0.1 to 0.5; If the deaerator vent pipe is a bend, k should be 0.5 to 1.

5.

8. The exhaust control device for a low-pressure steam drum deaerator of a gas-fired boiler according to claim 6, characterized in that: The method for obtaining v(x) is as follows: The following formula is used for calculation: In the formula, Q(x) represents the gas flow rate in the deaerator vent pipe when the vent valve opening is x, and A represents the cross-sectional area of ​​the deaerator vent pipe.

9. The exhaust control device for a low-pressure steam drum deaerator of a gas-fired boiler according to claim 2, characterized in that: The detection module (8) is selected as a zirconium oxide oxygen sensor.

10. The exhaust control device for a low-pressure steam drum deaerator of a gas-fired boiler according to claim 3, characterized in that: The flow sensing module (10) is selected as an ultrasonic gas flow meter.

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