Leak detection system for furnace tubes of a thermal power plant

Abstract

The present application relates to a kind of power plant furnace tube leakage detection systems, comprising: audio sensor and humidity sensor are arranged on each monitoring point of furnace tube;First high / low limit monitoring module, it monitors whether sound signal exceeds preset high limit value, if sound signal exceeds high limit value, it exports 1, otherwise 0;Second high / low limit monitoring module, it is configured to monitor whether humidity signal exceeds preset high limit value, if humidity signal exceeds high limit value, it exports 1, otherwise 0;Logic or function block, input end is connected to the output end of first high / low limit monitoring module;Logic and function block, input end is connected to the output end of second high / low limit monitoring module and logic or function block, its output end is connected to ALM alarm module and centralized control terminal, when sound signal and humidity signal all exceed preset high limit value, logic and function block exports 1, so that ALM alarm module and centralized control terminal respond, otherwise its output is 0.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of boiler tube leakage detection in thermal power plants. BACKGROUND

[0002] Boiler tubes in thermal power plants are special piping equipment that can withstand high temperature and high pressure, used for conveying liquids or gases. Boiler tubes are usually made of metal materials such as carbon steel, stainless steel and alloy steel, etc., which have strong texture and stable performance to adapt to the high temperature and high pressure working environment in thermal power plants. In thermal power plants, boiler tubes play an important role in conveying and heating medium, ensuring the smooth operation of the power generation process. Specifically, boiler tubes may include main steam pipes, hot reheat steam pipes, cold reheat steam pipes, etc., which are high temperature and high pressure steam pipes used to connect boilers and steam turbines to convey steam from boilers to steam turbines to drive generators to generate electricity. In addition, boiler tubes may also include other types of pipes such as high pressure feedwater pipes, etc. for supplying high pressure water to boilers. It should be noted that the importance of boiler tubes in thermal power plants is self-evident, and once a boiler tube leaks or fails, it will directly affect the operating efficiency and safety of the power plant. Therefore, thermal power plants need to regularly inspect and maintain boiler tubes to ensure they are in good working condition.

[0003] Currently, audio sensors are used to monitor boiler tube leakage. When a boiler tube leaks, the decibel value of the sound signal collected by the sensor will suddenly and continuously increase abnormally. According to the location of the abnormal sensor, the leakage point can be roughly determined. In the absence of other signal interference, audio sensors can normally monitor whether the boiler tube is leaking, but the internal structure of the boiler is complex, and when there is airflow circulation in the boiler during maintenance or repair, it is easy to interfere with the audio sensor, thereby causing false alarms, making the staff nervous, and affecting the judgment and operation of the boiler tube working condition. SUMMARY

[0004] The present application proposes a boiler tube leakage detection system for thermal power plants, which can shield interference factors through control logic to achieve rapid and accurate diagnosis of boiler tube leakage.

[0005] According to an aspect of the embodiments, a system for detecting a leakage of a boiler tube in a thermal power plant is provided. The system includes a plurality of audio sensors arranged on the boiler tube to monitor sound; a humidity sensor arranged on the boiler tube; a first FX module configured to output a filtered sound signal from a raw sound signal collected by the audio sensors according to a preset function correspondence; a second FX module configured to output a filtered humidity signal from a raw humidity signal collected by the humidity sensor according to a preset function correspondence; a first high / low limit monitoring module configured to monitor whether the processed sound signal output from the first FX module exceeds a preset high limit value; the first high / low limit monitoring module outputs 1 if the sound signal exceeds the high limit value, and outputs 0 if the sound signal does not exceed the high limit value; a second high / low limit monitoring module configured to monitor whether the processed humidity signal output from the second FX module exceeds a preset high limit value; the second high / low limit monitoring module outputs 1 if the humidity signal exceeds the high limit value, and outputs 0 if the humidity signal does not exceed the high limit value; an OR function block having an input end connected to an output end of the first high / low limit monitoring module, wherein the OR function block outputs 1 if the sound signal detected by any of the audio sensors exceeds the high limit value, and outputs 0 otherwise; an AND function block having input ends connected to output ends of the second high / low limit monitoring module and the OR function block, wherein the AND function block outputs 1 if both the sound signal and the humidity signal exceed the preset high limit value, and outputs 0 otherwise; and an ALM alarm module connected to the output end of the AND function block and configured to output an alarm information when the AND function block outputs 1.

[0006] In some examples, the high limit value of the sound signal is determined based on a sound of water vapor after a leakage of the boiler tube.

[0007] In some examples, the first FX module is further configured to filter out sound signals generated by non-leakage reasons of the boiler tube.

[0008] In some examples, the high limit value of the humidity signal is determined based on a humidity of an environment after a leakage of the boiler tube.

[0009] In some examples, the audio sensors and the humidity sensors are arranged on each monitoring point of the boiler tube.

[0010] In some examples, the output end of the AND function block is connected to a centralized control terminal.

[0011] In some examples, a human-machine interface of the centralized control terminal is configured to display state information of each monitoring point.

[0012] In some examples, the state information includes two state identifiers of leakage and non-leakage.

[0013] In some examples, when the output of the logical AND function block is 1, the human-machine interface of the centralized terminal will give an indication of a leakage state.

[0014] In some examples, when the output of the logical AND function block is 0, the human-machine interface of the centralized terminal will give an indication of a non-leakage state. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a control logic diagram of a boiler tube leakage detection system of a thermal power plant according to an embodiment of the present application. DETAILED DESCRIPTION

[0016] Figure 1 A control logic diagram of a boiler tube leakage detection system of a thermal power plant is shown. As shown in Figure 1 , the system comprises an audio sensor, an FX module, a high / low limit monitoring module, a logical OR function block, a logical AND function block, a centralized terminal, and an ALM alarm module.

[0017] The FX module is a function code used as a function generator to output the processed analog quantity value according to a preset function correspondence.

[0018] The OR is a logical OR function block, and its output is 1 as long as any one of the input conditions is 1.

[0019] The AND is a logical AND function block, and its output is 1 only when all the input conditions are 1.

[0020] The high / low limit monitoring module (abbreviated as H / L) is a function module for monitoring whether a variable exceeds a preset high (H) or low (L) limit value. For example, for the high / low limit monitoring module, if the input analog quantity value is within the preset high / low limit range, the output is 0; if the input analog quantity value exceeds the range (i.e., is higher than the high limit or lower than the low limit), the output is 1.

[0021] A plurality of audio sensors are arranged at various points of the boiler tube to monitor the leakage steam sound and the interference gas sound.

[0022] Each audio sensor corresponds to a first FX module and a first high / low limit monitoring module. The audio sensor, the first FX module and the first high / low limit monitoring module are connected in sequence. The audio sensor transmits the collected original sound signal (analog quantity) to the first FX module, which serves as a function generator for processing and converting (e.g. filtering) the signals according to a preset function relationship. If the sound signal input to the first high / low limit monitoring module from the first FX module is within the preset high / low limit range, the first high / low limit monitoring module outputs '0'; if the sound signal input to the first high / low limit monitoring module from the first FX module exceeds the range (e.g. higher than the high limit), the first high / low limit monitoring module outputs '1'. The high limit and low limit values can be determined by monitoring a large number of sound signals of leaking steam and interfering gas on site, so as to ensure that the sensor can effectively respond to the sound signals of steam leakage and interfering gas.

[0023] In another embodiment, the first FX module can also be configured to filter out sound signals generated by non-furnace tube leakage causes. For example, the noise generated during the maintenance of the furnace tube can be filtered out by the first FX module, because such noise is significantly different from the sound emitted by the leaking steam. Interfering sounds similar to the sound emitted by the leaking steam are distinguished by the following logic device.

[0024] The first high / low limit monitoring modules of all audio sensors are connected to a logic OR (OR) function block, which will trigger the corresponding response when the sound signal detected by any audio sensor exceeds the set high limit, and output '1', otherwise output '0'.

[0025] In order to effectively distinguish whether the sound signal is generated by leaking steam or interfering gas, a humidity sensor is also installed at each monitoring point. Because the humidity in the environment will increase significantly after the furnace tube leaks. Similarly, each humidity sensor corresponds to a second FX module and a second high / low limit monitoring module. The humidity sensor transmits the collected original humidity signal (analog quantity) to the second FX module, which serves as a function generator for processing and converting (e.g. filtering) the signals according to a preset function relationship. If the humidity signal input to the second high / low limit monitoring module from the second FX module is within the preset high / low limit range, the second high / low limit monitoring module outputs '0'; if the humidity signal input to the second high / low limit monitoring module from the second FX module exceeds the range (e.g. higher than the high limit), the second high / low limit monitoring module outputs '1'. The high limit and low limit values can be determined by monitoring a large number of humidity signals of leaking steam on site, so as to ensure that the humidity sensor can effectively respond to the steam leakage.

[0026] The output end of the logic OR (OR) function block and the output end of the second high / low limit monitoring module are connected to the input end of a logic AND (AND) function block, and the output end of the logic AND function block is connected to the centralized control terminal and the ALM alarm module. When the sound signal detected by any one of the audio sensors exceeds the set high limit value, and the humidity signal detected by the humidity sensor also exceeds the set high limit value, the logic AND function block will output '1'. At this time, the ALM alarm module will issue an alarm, the human-computer interface of the centralized control terminal will display a leakage reminder, and the specific point of the leakage will be indicated according to the position information of the sensor. For example, when the output of the logic AND function block is 1, the human-computer interface of the centralized control terminal will give an identification of the leakage state; when the output of the logic AND function block is 0, the human-computer interface of the centralized control terminal will give an identification of the non-leakage state.

[0027] The FX module, the high / low limit monitoring module, the logic OR function block, the logic AND function block, the centralized control terminal and the ALM alarm module in the application can be configured and implemented in a DCS system.

[0028] In summary, the application uses humidity and sound as necessary conditions for judging the leakage of the furnace tube, and solves the problem that the use of sound as a single judgment standard is easily disturbed by external airflow.

Claims

1. A leak detection system for boiler tubes in a thermal power plant, characterized in that, Comprising: a plurality of audio sensors arranged to monitor sound on the furnace tube; a humidity sensor arranged on the furnace tube; a first FX module configured to output filtered sound signals collected by the audio sensors; a second FX module configured to output filtered humidity signals collected by the humidity sensor; a first high / low limit monitoring module configured to monitor whether the filtered sound signals outputted by the first FX module exceed a preset high limit value; if the sound signals exceed the high limit value, the output of the first high / low limit monitoring module is 1; if the high limit value is not exceeded, the output is 0; a second high / low limit monitoring module configured to monitor whether the filtered humidity signals outputted by the second FX module exceed a preset high limit value; if the humidity signals exceed the high limit value, the output of the second high / low limit monitoring module is 1; if the high limit value is not exceeded, the output is 0; a logic OR function block having input terminals connected to the output terminals of the first high / low limit monitoring module, wherein if the sound signals detected by any of the audio sensors exceed the high limit value, the output of the logic OR function block is 1, otherwise its output is 0; a logic AND function block having input terminals connected to the output terminals of the second high / low limit monitoring module and the logic OR function block, wherein if both the sound signals and the humidity signals exceed the preset high limit value, the output of the logic AND function block is 1 to indicate that the furnace tube is leaking, otherwise its output is 0 to indicate that the furnace tube is not leaking; and an ALM alarm module connected to the output terminal of the logic AND function block and configured to send an alarm message when the output of the logic AND function block is 1. The high limit value of the sound signals is determined based on the sound of water vapor after the furnace tube leaks.

2. The power plant furnace tube leak detection system of claim 1, wherein, The first FX module is further configured to filter out sound signals generated by non-furnace tube leakage causes.

3. The power plant furnace tube leak detection system of claim 2, wherein, The high limit value of the humidity signals is determined based on the humidity of the environment after the furnace tube leaks.

4. The power plant furnace tube leak detection system of claim 1, wherein, The audio sensors and the humidity sensors are arranged on each monitoring point of the furnace tube.

5. The system for detecting a leak in a boiler tube of a fossil fuel power plant of any of claims 1-4, wherein, The output terminal of the logic AND function block is connected to a centralized control terminal.

6. The power plant furnace tube leak detection system of claim 5, wherein, The human-machine interface of the centralized control terminal is configured to display state information of each monitoring point.

7. The power plant furnace tube leak detection system of claim 6, wherein, The state information includes two state identifiers, i.e., leakage and no leakage.

8. The power plant furnace tube leak detection system of claim 7, wherein, When the output of the logic AND function block is 1, the human-machine interface of the centralized control terminal displays the identifier of the leakage state.

9. The power plant furnace tube leak detection system of claim 8, wherein, When the output of the logic AND function block is 0, the human-machine interface of the centralized control terminal displays the identifier of the no leakage state.

10. The power plant furnace tube leak detection system of claim 8, wherein, ​

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