Control method for natural gas cold and heat cogeneration

Abstract

The invention belongs to the technical field of waste heat recovery control, and provides a natural gas cold and heat cogeneration control method, which comprises the following steps: setting a monitoring period, monitoring two ends of each natural gas conveying pipeline to obtain natural gas temperature data, analyzing and processing the natural gas temperature data to obtain an ideal heat recovery value, and controlling the heat recovery value. Analyzing and processing the natural gas temperature data again to obtain an actual heat recovery value, acquiring a gas flow in each natural gas conveying pipeline in a monitoring time period, obtaining a gas flow mean value, processing the actual heat recovery value and a theoretical heat recovery value, outputting to obtain a heat recovery efficiency value, and comparing the heat recovery efficiency value with a threshold value; if the heat recovery efficiency value is smaller than the heat recovery efficiency threshold value, it is indicated that the heat recovery efficiency of the heat recovery system in actual operation is low, and a low recovery efficiency signal is generated, so that comprehensive evaluation on the heat recovery efficiency of the heat recovery system is completed by setting a monitoring period.

Description

Technical Field

[0001] The invention belongs to the technical field of waste heat recovery control, in particular to a control method for natural gas cooling and heating cogeneration. Background Art

[0002] Combined cooling and heating is more accurately known as combined cooling, heating and power. It is a total energy system based on the concept of energy cascade utilization. It integrates refrigeration, heating (including heating and hot water supply) and power generation processes. This system can produce three products, electricity, heat and cooling, at the same time, thereby greatly improving the efficiency of energy utilization. In the process of using natural gas for power generation, the waste heat recovery system will recycle the heat energy generated by power generation. However, due to the influence of excess air, the waste heat recovery system will be affected when recovering heat energy.

[0003] In the prior art, the natural gas combined heat and cooling system uses an internal combustion engine to burn natural gas as energy to drive a generator to generate electricity. In this process, the internal combustion engine will generate a large amount of waste heat, including flue gas waste heat, and the natural gas combined heat and cooling system also includes a waste heat recovery system, whose main function is to recover and utilize this waste heat. However, in the process of using natural gas as fuel for combustion, in order to ensure that the fuel can be fully burned, usually more air than the theoretical requirement is provided. This extra air is excess air. If the excess air is too much, the flue gas out of the furnace will take away a large amount of heat, resulting in a decrease in thermal efficiency, thereby causing the heat recovery efficiency of the waste heat recovery system to decrease. Therefore, it is necessary to monitor and evaluate the heat recovery efficiency, and when the heat recovery efficiency is low, analyze the correlation between the excess air and the heat recovery efficiency, and optimize and adjust the excess air according to the correlation between the excess air and the heat recovery efficiency, so as to solve the problem of low waste heat recovery efficiency caused by excess air.

[0004] To this end, the present invention provides a control method for natural gas cooling and heating cogeneration. Summary of the invention

[0005] In order to make up for the deficiencies of the prior art, the problem of low waste heat recovery efficiency due to excessive excess air volume mentioned in the background technology is solved.

[0006] The technical solution adopted by the present invention to solve its technical problem is: A control method for natural gas cooling and heating cogeneration, comprising: Step 1: Set a monitoring cycle, monitor both ends of each natural gas transmission pipeline, obtain natural gas temperature data, analyze and process the natural gas temperature data, and obtain the ideal heat recovery value; Step 2: Analyze and process the natural gas temperature data again to obtain the actual heat recovery value, and obtain the gas flow in each natural gas transmission pipeline during the monitoring period to obtain the gas flow average, process the actual heat recovery value and the theoretical heat recovery value, output the heat recovery efficiency value, and compare it with the threshold to generate a recovery efficiency high or low signal; The recovery efficiency high and low signal includes a recovery efficiency high signal or a recovery efficiency low signal; Step 3: Based on the low recovery efficiency signal, excess air data is obtained within the monitoring period, wherein the excess air data includes the excess air value, and the excess air data within each monitoring period is analyzed and processed to obtain a correlation analysis value, and compared with the threshold value. If the correlation analysis value is greater than or equal to the correlation analysis threshold value, it means that the correlation and consistency between the excess air change and the unit heat recovery value change are stronger, that is, the stronger the correlation between the two, the greater the excess impact signal is generated; Step 4: Based on the large excess impact signal, obtain the control adjustment coefficient and complete the control adjustment of the excess air volume.

[0007] As a further solution of the present invention: the ideal heat recovery value is obtained by: The monitoring cycle is divided into several monitoring periods, and the natural gas temperature data at the inlet and outlet ends of the natural gas transmission pipeline are respectively obtained during the monitoring period, wherein the natural gas temperature data includes the inlet temperature and the outlet temperature; During the monitoring period, the inlet temperature is subtracted from the outlet temperature to obtain the temperature change value; During the monitoring period, all temperature change values ​​are compared, and the maximum temperature change value is extracted and marked as the temperature recovery sub-value; The temperature recovery sub-values ​​corresponding to all natural gas transmission pipelines are added together and averaged to obtain the ideal heat recovery value.

[0008] As a further solution of the present invention: the unit heat recovery value is obtained in the following manner: Obtain the temperature change value in each monitoring period, add and average all the temperature change values ​​in the monitoring period, and obtain the temperature change mean; During the monitoring period, the gas flow in the natural gas transmission pipeline is obtained and marked as the period flow. The period flows corresponding to all monitoring periods in the monitoring cycle are added and averaged to obtain the gas flow mean; The unit heat recovery value is obtained by multiplying the mean gas flow rate and the mean temperature change.

[0009] As a further solution of the present invention: the heat recovery efficiency value is obtained in the following manner: The unit heat recovery values ​​corresponding to each natural gas transmission pipeline are added and averaged to obtain the actual heat recovery value; The heat recovery efficiency value is obtained by calculating the ratio of the actual heat recovery value to the theoretical heat recovery value.

[0010] As a further solution of the present invention: the heat recovery efficiency value is compared with the heat recovery efficiency threshold value, and the comparison process is as follows: If the heat recovery efficiency value is greater than or equal to the heat recovery efficiency threshold, a high recovery efficiency signal is generated; If the heat recovery efficiency value is less than the heat recovery efficiency threshold, a low recovery efficiency signal is generated.

[0011] As a further solution of the present invention: the method of obtaining the excess sub-polyline segments is: An XY axis coordinate system is established, wherein the X axis represents the monitoring period and the Y axis represents the excess air value. The excess air value in each monitoring period is substituted into the XY axis coordinate system and plotted to obtain an excess air change curve; The excess air change curve is divided into a number of excess change sub-curve segments, the end point coordinates and the center coordinates of each excess change sub-curve segment are obtained, and they are marked as excess initial coordinates, excess center coordinates and excess end coordinates respectively, and the excess initial coordinates, excess center coordinates and excess end coordinates are sequentially connected with straight lines to obtain excess sub-broken line segments; The method for obtaining the recycled sub-polyline segment is: Establish an XY axis coordinate system, where the X axis represents the monitoring period and the Y axis represents the unit heat recovery value. Substitute the unit heat recovery value in each monitoring period into the XY axis coordinate system and draw a heat recovery change curve; The heat recovery change curve is divided into several recovery change sub-curve segments, and the coordinates of the endpoints and the center coordinates of each recovery change sub-curve segment are obtained, and they are marked as the recovery initial coordinates, the recovery center coordinates and the recovery end coordinates respectively. The recovery initial coordinates, the recovery center coordinates and the recovery end coordinates are connected in sequence with a straight line to obtain a recovery sub-broken line segment.

[0012] As a further solution of the present invention: the same trend period ratio is obtained in the following manner: During the monitoring period, the opening directions of the excess sub-broken line segments and the opening directions of the recovery sub-broken line segments in the same monitoring period are extracted, and the opening directions of the excess sub-broken line segments and the opening directions of the recovery sub-broken line segments in the same monitoring period are compared. The comparison process is as follows: If the opening direction of the surplus sub-line segment is consistent with the opening direction of the recovery sub-line segment in the same monitoring period, the monitoring period with the same opening direction is marked as the same trend period; During the monitoring period, the number of time periods with the same trend is counted to obtain the total number of time periods with the same trend. The ratio of the total number of time periods with the total number of all monitoring time periods in the monitoring period is calculated to obtain the ratio of time periods with the same trend.

[0013] As a further solution of the present invention: the similarity change ratio is obtained as follows: Based on the same trend period, the excess change sub-curve segments corresponding to the same trend period are extracted and marked as excess same sub-curve segments; Obtain the coordinates of the two end points of the excess sub-curve segment, mark them as the same excess initial coordinate and the same excess final coordinate, connect the same excess initial coordinate and the same excess final coordinate to obtain the same excess line segment; Based on the same trend period, the recovery change sub-curve segments corresponding to the same trend period are extracted and marked as the recovery same sub-curve segments; Obtain the coordinates of the two end points of the recovered same sub-curve segment, mark them as the same recovery initial coordinates and the same recovery final coordinates respectively, connect the same recovery initial coordinates and the same recovery final coordinates to obtain the same recovery line segment; In the same trend period, obtain the slope value corresponding to the same excess line segment and mark it as the same excess slope; In the same trend period, obtain the slope value corresponding to the same recovery line segment and mark it as the same recovery slope; During the monitoring period, the same excess slope and the same recovery slope in the same trend period are extracted, and the same excess slope and the same recovery slope in the same trend period are calculated by ratio to obtain the unit change ratio; During the monitoring period, the variance of the unit change ratios corresponding to all the same trend periods is calculated to obtain similar change ratios.

[0014] As a further solution of the present invention: the method of obtaining the association analysis value is: Calculate the ratio of the same trend period to the similar change ratio to obtain the correlation analysis value.

[0015] As a further solution of the present invention: the control and adjustment process of the excess air volume is as follows: During the monitoring period, the unit change ratio corresponding to each monitoring period is obtained, and the unit change ratios corresponding to all monitoring periods are added and averaged to obtain the control adjustment coefficient; Substitute the control adjustment factor and the current excess air volume into the formula: , calculate the adjusted excess air volume , where K represents the control adjustment coefficient, Indicates the current excess air volume.

[0016] The beneficial effects of the present invention are as follows: (1) The present invention sets a monitoring cycle, monitors both ends of each natural gas transmission pipeline, obtains natural gas temperature data, analyzes and processes the natural gas temperature data to obtain an ideal heat recovery value, analyzes and processes the natural gas temperature data again to obtain an actual heat recovery value, and obtains the gas flow in each natural gas transmission pipeline during the monitoring period to obtain the gas flow average, processes the actual heat recovery value and the theoretical heat recovery value, outputs a heat recovery efficiency value, and compares it with a threshold value. If the heat recovery efficiency value is less than the heat recovery efficiency threshold value, it means that the heat recovery efficiency of the heat recovery system in actual operation is low, and a low recovery efficiency signal is generated, thereby completing a comprehensive evaluation of the heat recovery efficiency of the heat recovery system by setting a monitoring cycle; (2) When the present invention generates a low recovery efficiency signal, within the monitoring period, the flue gas analyzer is used to obtain the excess air data corresponding to each monitoring period within the monitoring period, wherein the excess air data includes the excess air value, and the excess air value and the unit heat recovery value within each monitoring period are analyzed and processed to obtain a correlation analysis value, which is compared with the threshold value. If the correlation analysis value is greater than or equal to the correlation analysis threshold value, a large excess influence signal is generated, thereby analyzing that the stronger the correlation and consistency between the excess air change and the unit heat recovery value change, that is, the stronger the correlation between the two, and then determining that the excessive excess air volume is the cause of the low waste heat recovery efficiency; (3) When the present invention generates a large excess impact signal, the unit change ratio corresponding to each monitoring period is taken, the unit change ratios corresponding to all monitoring periods are added and averaged to obtain a control adjustment coefficient, and the control adjustment coefficient and the current excess air volume are substituted into the formula to calculate the adjusted excess air volume, thereby solving the problem of low waste heat recovery efficiency due to excessive excess air volume. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described below in conjunction with the accompanying drawings.

[0018] Figure 1 is a flowchart of the steps of Embodiment 1 of the present invention; Figure 2 is a flowchart of the steps of Embodiment 2 of the present invention; Figure 3 It is a step flow chart of Example 3 of the present invention. DETAILED DESCRIPTION

[0019] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0020] Example 1 like Figure 1As shown, a natural gas cooling and heating cogeneration control method according to an embodiment of the present invention comprises: Step 1: Set a monitoring cycle, monitor both ends of each natural gas transmission pipeline, obtain natural gas temperature data, analyze and process the natural gas temperature data, and obtain the ideal heat recovery value; In some embodiments, the monitoring cycle is divided into several monitoring periods. During the monitoring period, the natural gas temperature data at the inlet and outlet of the natural gas transmission pipeline are respectively obtained, wherein the natural gas temperature data includes the inlet temperature and the outlet temperature. The analysis and processing are performed based on the inlet temperature and the outlet temperature. The specific processing process is as follows: It should be noted that the monitoring period is divided into monitoring time periods by dividing the monitoring period into equal time intervals, and the time of each monitoring time period is equal; Specifically, during the monitoring period, the inlet temperature is subtracted from the outlet temperature to obtain a temperature change value; During the monitoring period, all temperature change values ​​are compared, and the maximum temperature change value is extracted and marked as the temperature recovery sub-value; The temperature recovery sub-values ​​corresponding to all natural gas transmission pipelines are added and averaged to obtain the ideal heat recovery value; It can be understood that the ideal heat recovery value means: the maximum heat value that the heat recovery system can recover from the flowing natural gas. This value is a theoretical upper limit, which represents the maximum heat recovery capacity of the system under optimal conditions. Step 2: Analyze and process the natural gas temperature data again to obtain the actual heat recovery value, and obtain the gas flow in each natural gas transmission pipeline during the monitoring period to obtain the gas flow average, process the actual heat recovery value and the theoretical heat recovery value, output the heat recovery efficiency value, and compare it with the threshold to generate a recovery efficiency high or low signal; The recovery efficiency high and low signal includes a recovery efficiency high signal or a recovery efficiency low signal; In some embodiments, the temperature change value in each monitoring period is obtained, and all the temperature change values ​​in the monitoring period are added and averaged to obtain the temperature change average; During the monitoring period, the gas flow in the natural gas transmission pipeline is obtained and marked as the period flow. The period flows corresponding to all monitoring periods in the monitoring cycle are added and averaged to obtain the gas flow mean; The unit heat recovery value is obtained by multiplying the mean value of gas flow rate and the mean value of temperature change; It can be understood that the meaning of the unit heat recovery value is: reflecting the comprehensive effect of the heat energy carried by the gas flow and the temperature change in a single natural gas transmission pipeline during the monitoring period. Specifically, the larger the value, the higher the actual heat recovery degree of the single natural gas during the monitoring period, and the stronger the heat recovery capacity. On the contrary, the smaller the value, the lower the actual heat recovery degree of the archived natural gas during the monitoring period, and the weaker the heat recovery capacity. The unit heat recovery values ​​corresponding to each natural gas transmission pipeline are added and averaged to obtain the actual heat recovery value; The actual heat recovery value is calculated by comparing it with the theoretical heat recovery value to obtain the heat recovery efficiency value; It can be understood that the heat recovery efficiency value means: the ratio between the heat energy actually recovered by the natural gas transmission pipeline system and the heat energy that can be recovered theoretically during the monitoring period. It reflects the heat recovery efficiency of the heat recovery system. The higher this value is, the higher the heat recovery efficiency of the heat recovery system in actual operation is; conversely, the lower this value is, the lower the heat recovery efficiency of the heat recovery system in actual operation is. The heat recovery efficiency value is compared with the heat recovery efficiency threshold value. The comparison process is as follows: If the heat recovery efficiency value is greater than or equal to the heat recovery efficiency threshold, it means that the heat recovery efficiency of the heat recovery system in actual operation is high, and a high recovery efficiency signal is generated; If the heat recovery efficiency value is less than the heat recovery efficiency threshold, it means that the heat recovery efficiency of the heat recovery system in actual operation is low, and a low recovery efficiency signal is generated; The specific implementation plan of the embodiment of the present invention is: setting a monitoring cycle, monitoring both ends of each natural gas transmission pipeline, obtaining natural gas temperature data, analyzing and processing the natural gas temperature data to obtain an ideal heat recovery value, analyzing and processing the natural gas temperature data again to obtain an actual heat recovery value, and obtaining the gas flow in each natural gas transmission pipeline during the monitoring period to obtain the gas flow average, processing the actual heat recovery value and the theoretical heat recovery value, outputting a heat recovery efficiency value, and comparing it with a threshold value. If the heat recovery efficiency value is less than the heat recovery efficiency threshold value, it means that the heat recovery efficiency of the heat recovery system in actual operation is low, and a low recovery efficiency signal is generated, so that by setting a monitoring cycle, a comprehensive evaluation of the heat recovery efficiency of the heat recovery system is completed.

[0021] Example 2 like Figure 2 As shown, based on Example 1, a natural gas cooling and heating cogeneration control method according to an embodiment of the present invention includes: Step 3: Based on the low recovery efficiency signal, excess air data is obtained within the monitoring period, and the excess air data within each monitoring period is analyzed and processed to obtain a correlation analysis value, which is compared with the threshold value to generate an excess impact signal; The excess impact signal includes a large excess impact signal or a small excess impact signal; In some embodiments, when a low recovery efficiency signal is generated, the flue gas analyzer is used to obtain excess air data corresponding to each monitoring period in the monitoring cycle, wherein the excess air data includes excess air values, and the excess air values ​​in each monitoring period are analyzed and processed with the unit heat recovery value, and the specific process is as follows: An XY axis coordinate system is established, wherein the X axis represents the monitoring period and the Y axis represents the excess air value. The excess air value in each monitoring period is substituted into the XY axis coordinate system and plotted to obtain an excess air change curve; Establish an XY axis coordinate system, where the X axis represents the monitoring period and the Y axis represents the unit heat recovery value. Substitute the unit heat recovery value in each monitoring period into the XY axis coordinate system and draw a heat recovery change curve; Based on the excess air change curve, the excess air change curve is divided into a number of excess change sub-curve segments, the end point coordinates and the center coordinates of both ends of each excess change sub-curve segment are obtained, and they are marked as excess initial coordinates, excess center coordinates and excess end coordinates respectively, and the excess initial coordinates, excess center coordinates and excess end coordinates are sequentially connected with straight lines to obtain excess sub-polyline segments; It should be noted that the excess air change curve is divided in the following manner: the excess air change curve is divided according to the monitoring time periods within the monitoring cycle to obtain a number of excess change sub-curve segments; Based on the heat recovery change curve, the heat recovery change curve is divided into several recovery change sub-curve segments, the coordinates of the endpoints and the center coordinates of each recovery change sub-curve segment are obtained, and they are marked as recovery initial coordinates, recovery center coordinates and recovery end coordinates respectively, and the recovery initial coordinates, recovery center coordinates and recovery end coordinates are sequentially connected with straight lines to obtain recovery sub-broken line segments; It should be noted that the way the heat recovery variation curve is divided is the same as the way the excess air variation curve is divided above; During the monitoring period, the opening directions of the excess sub-broken line segments and the opening directions of the recovery sub-broken line segments in the same monitoring period are extracted, and the opening directions of the excess sub-broken line segments and the opening directions of the recovery sub-broken line segments in the same monitoring period are compared. The comparison process is as follows: If the opening direction of the surplus sub-line segment is consistent with the opening direction of the recovery sub-line segment in the same monitoring period, the monitoring period with the same opening direction is marked as the same trend period; If the opening direction of the surplus sub-line segment is inconsistent with the opening direction of the recovery sub-line segment in the same monitoring period, the monitoring periods with inconsistent opening directions are marked as different trend periods; During the monitoring period, the number of time periods with the same trend is counted to obtain the total number of time periods with the same trend. The total number of time periods with the total number of all monitoring time periods in the monitoring period is calculated to obtain the same trend time period ratio. Based on the same trend period, the excess change sub-curve segments corresponding to the same trend period are extracted and marked as excess same sub-curve segments; Obtain the coordinates of the two end points of the excess sub-curve segment, mark them as the same excess initial coordinate and the same excess final coordinate, connect the same excess initial coordinate and the same excess final coordinate to obtain the same excess line segment; Based on the same trend period, the recovery change sub-curve segments corresponding to the same trend period are extracted and marked as the recovery same sub-curve segments; Obtain the coordinates of the two end points of the recovered same sub-curve segment, mark them as the same recovery initial coordinates and the same recovery final coordinates respectively, connect the same recovery initial coordinates and the same recovery final coordinates to obtain the same recovery line segment; In the same trend period, obtain the slope value corresponding to the same excess line segment and mark it as the same excess slope; In the same trend period, obtain the slope value corresponding to the same recovery line segment and mark it as the same recovery slope; During the monitoring period, the same excess slope and the same recovery slope in the same trend period are extracted, and the same excess slope and the same recovery slope in the same trend period are calculated by ratio to obtain the unit change ratio; During the monitoring period, the variance of the unit change ratios corresponding to all the same trend periods is calculated to obtain similar change ratios; Calculate the ratio of the same trend period to the similar change ratio to obtain the correlation analysis value; It can be understood that the meaning of the correlation analysis value is: a quantitative indicator of the correlation degree and consistency level between the excess air change and the unit heat recovery value change during the monitoring period. This correlation analysis value is a comprehensive reflection of the correlation degree between the excess air and unit heat recovery values ​​by comparing their changing trends (i.e., whether the opening directions are consistent), the amplitude of change (reflected by the slope ratio) and the proportion of the same trend period in different monitoring periods. Specifically, the larger this value is, the stronger the correlation and consistency between the excess air change and the unit heat recovery value change is, that is, the stronger the correlation degree between the two is. Conversely, the smaller this value is, the weaker the correlation and consistency between the excess air change and the unit heat recovery value change is, that is, the weaker the correlation degree between the two is. The association analysis value is compared with the association analysis threshold. The comparison process is as follows: If the correlation analysis value is greater than or equal to the correlation analysis threshold, it means that the correlation and consistency between the excess air change and the unit heat recovery value change are stronger, that is, the stronger the correlation between the two, the greater the excess impact signal is generated; If the correlation analysis value is less than the correlation analysis threshold, it means that the correlation and consistency between the excess air change and the unit heat recovery value change are weaker, that is, the correlation between the two is weaker, and a small excess impact signal is generated; The specific implementation plan of the embodiment of the present invention is: when a low recovery efficiency signal is generated, within the monitoring cycle, a flue gas analyzer is used to obtain excess air data corresponding to each monitoring period within the monitoring cycle, wherein the excess air data includes excess air values, and the excess air values ​​and unit heat recovery values ​​in each monitoring period are analyzed and processed to obtain a correlation analysis value, and compared with a threshold value. If the correlation analysis value is greater than or equal to the correlation analysis threshold, a large excess impact signal is generated, thereby analyzing the correlation and consistency between the changes in excess air and the changes in the unit heat recovery value, that is, the stronger the correlation between the two, and then determining that the excessive amount of excess air is the cause of the low waste heat recovery efficiency.

[0022] Example 3 like Figure 3 As shown, based on Example 1 and Example 2, a natural gas cooling and heating cogeneration control method according to an embodiment of the present invention includes: Step 4: Based on the large excess impact signal, obtain the control adjustment coefficient and complete the control adjustment of the excess air volume; In some embodiments, when a large excess impact signal is generated, a control adjustment coefficient is obtained, and the specific process is as follows: During the monitoring period, the unit change ratio corresponding to each monitoring period is obtained, and the unit change ratios corresponding to all monitoring periods are added and averaged to obtain the control adjustment coefficient; Specifically, the control and adjustment process of excess air volume is as follows: Substitute the control adjustment factor and the current excess air volume into the formula: , calculate the adjusted excess air volume , where K represents the control adjustment coefficient, Expressed as the current excess air volume; The specific implementation plan of the embodiment of the present invention is: when a large excess impact signal is generated, the unit change ratio corresponding to each monitoring period is taken, the unit change ratios corresponding to all monitoring periods are added and averaged to obtain a control adjustment coefficient, and the control adjustment coefficient and the current excess air volume are substituted into the formula to calculate the adjusted excess air volume, thereby solving the problem of low waste heat recovery efficiency due to excessive excess air volume.

[0023] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A control method for natural gas cooling and heating cogeneration, characterized in that: include: Step 1: Set a monitoring cycle, monitor both ends of each natural gas transmission pipeline, obtain natural gas temperature data, analyze and process the natural gas temperature data, and obtain the ideal heat recovery value; Step 2: Analyze and process the natural gas temperature data again to obtain the actual heat recovery value, and obtain the gas flow in each natural gas transmission pipeline during the monitoring period to obtain the gas flow average, process the actual heat recovery value and the theoretical heat recovery value, output the heat recovery efficiency value, and compare it with the threshold to generate a recovery efficiency high or low signal; The recovery efficiency high and low signal includes a recovery efficiency high signal or a recovery efficiency low signal; Step 3: Based on the low recovery efficiency signal, excess air data is obtained within the monitoring period, wherein the excess air data includes the excess air value, and the excess air data within each monitoring period is analyzed and processed to obtain a correlation analysis value, and compared with the threshold value. If the correlation analysis value is greater than or equal to the correlation analysis threshold value, it means that the correlation and consistency between the excess air change and the unit heat recovery value change are stronger, that is, the stronger the correlation between the two, the greater the excess impact signal is generated; Step 4: Based on the large excess impact signal, obtain the control adjustment coefficient and complete the control adjustment of the excess air volume.

2. A natural gas cooling and heating cogeneration control method according to claim 1, characterized in that: The ideal heat recovery value is obtained as follows: The monitoring cycle is divided into several monitoring periods, and the natural gas temperature data at the inlet and outlet ends of the natural gas transmission pipeline are respectively obtained during the monitoring period, wherein the natural gas temperature data includes the inlet temperature and the outlet temperature; During the monitoring period, the inlet temperature is subtracted from the outlet temperature to obtain the temperature change value; During the monitoring period, all temperature change values ​​are compared, and the maximum temperature change value is extracted and marked as the temperature recovery sub-value; The temperature recovery sub-values ​​corresponding to all natural gas transmission pipelines are added together and averaged to obtain the ideal heat recovery value.

3. A natural gas cooling and heating cogeneration control method according to claim 1, characterized in that: The unit heat recovery value is obtained as follows: Obtain the temperature change value in each monitoring period, add and average all the temperature change values ​​in the monitoring period, and obtain the temperature change mean; During the monitoring period, the gas flow in the natural gas transmission pipeline is obtained and marked as the period flow. The period flows corresponding to all monitoring periods in the monitoring cycle are added and averaged to obtain the gas flow mean; The unit heat recovery value is obtained by multiplying the mean gas flow rate and the mean temperature change.

4. A natural gas cooling and heating cogeneration control method according to claim 3, characterized in that: The heat recovery efficiency value is obtained as follows: The unit heat recovery values ​​corresponding to each natural gas transmission pipeline are added and averaged to obtain the actual heat recovery value; The heat recovery efficiency value is obtained by calculating the ratio of the actual heat recovery value to the theoretical heat recovery value.

5. A natural gas cooling and heating cogeneration control method according to claim 1, characterized in that: The heat recovery efficiency value is compared with the heat recovery efficiency threshold value. The comparison process is as follows: If the heat recovery efficiency value is greater than or equal to the heat recovery efficiency threshold, a high recovery efficiency signal is generated; If the heat recovery efficiency value is less than the heat recovery efficiency threshold, a low recovery efficiency signal is generated.

6. A natural gas cooling and heating cogeneration control method according to claim 1, characterized in that: The method for obtaining excess sub-polyline segments is as follows: An XY axis coordinate system is established, wherein the X axis represents the monitoring period and the Y axis represents the excess air value. The excess air value in each monitoring period is substituted into the XY axis coordinate system and plotted to obtain an excess air change curve; The excess air change curve is divided into a number of excess change sub-curve segments, the end point coordinates and the center coordinates of each excess change sub-curve segment are obtained, and they are marked as excess initial coordinates, excess center coordinates and excess end coordinates respectively, and the excess initial coordinates, excess center coordinates and excess end coordinates are sequentially connected with straight lines to obtain excess sub-broken line segments; The method for obtaining the recycled sub-polyline segment is: Establish an XY axis coordinate system, where the X axis represents the monitoring period and the Y axis represents the unit heat recovery value. Substitute the unit heat recovery value in each monitoring period into the XY axis coordinate system and draw a heat recovery change curve; The heat recovery change curve is divided into several recovery change sub-curve segments, and the coordinates of the endpoints and the center coordinates of each recovery change sub-curve segment are obtained, and they are marked as the recovery initial coordinates, the recovery center coordinates and the recovery end coordinates respectively. The recovery initial coordinates, the recovery center coordinates and the recovery end coordinates are connected in sequence with a straight line to obtain a recovery sub-broken line segment.

7. A natural gas cooling and heating cogeneration control method according to claim 6, characterized in that: The method for obtaining the same trend period ratio is: During the monitoring period, the opening directions of the excess sub-broken line segments and the opening directions of the recovery sub-broken line segments in the same monitoring period are extracted, and the opening directions of the excess sub-broken line segments and the opening directions of the recovery sub-broken line segments in the same monitoring period are compared. The comparison process is as follows: If the opening direction of the surplus sub-line segment is consistent with the opening direction of the recovery sub-line segment in the same monitoring period, the monitoring period with the same opening direction is marked as the same trend period; During the monitoring period, the number of time periods with the same trend is counted to obtain the total number of time periods with the same trend. The ratio of the total number of time periods with the total number of all monitoring time periods in the monitoring period is calculated to obtain the ratio of time periods with the same trend.

8. A natural gas cooling and heating cogeneration control method according to claim 6, characterized in that: The similarity change ratio is obtained as follows: Based on the same trend period, the excess change sub-curve segments corresponding to the same trend period are extracted and marked as excess same sub-curve segments; Obtain the coordinates of the two end points of the excess sub-curve segment, mark them as the same excess initial coordinate and the same excess final coordinate, connect the same excess initial coordinate and the same excess final coordinate to obtain the same excess line segment; Based on the same trend period, the recovery change sub-curve segments corresponding to the same trend period are extracted and marked as the recovery same sub-curve segments; Obtain the coordinates of the two end points of the recovered same sub-curve segment, mark them as the same recovery initial coordinates and the same recovery final coordinates respectively, connect the same recovery initial coordinates and the same recovery final coordinates to obtain the same recovery line segment; In the same trend period, obtain the slope value corresponding to the same excess line segment and mark it as the same excess slope; In the same trend period, obtain the slope value corresponding to the same recovery line segment and mark it as the same recovery slope; During the monitoring period, the same excess slope and the same recovery slope in the same trend period are extracted, and the same excess slope and the same recovery slope in the same trend period are calculated by ratio to obtain the unit change ratio; During the monitoring period, the variance of the unit change ratios corresponding to all the same trend periods is calculated to obtain similar change ratios.

9. A natural gas cooling and heating cogeneration control method according to claim 1, characterized in that: The association analysis value is obtained as follows: The ratio of the same trend period to the similar change ratio is calculated to obtain the correlation analysis value.

10. A natural gas cooling and heating cogeneration control method according to claim 1, characterized in that: The control and adjustment process of excess air volume is as follows: During the monitoring period, the unit change ratio corresponding to each monitoring period is obtained, and the unit change ratios corresponding to all monitoring periods are added and averaged to obtain the control adjustment coefficient; Substitute the control adjustment factor and the current excess air volume into the formula: , calculate the adjusted excess air volume , where K represents the control adjustment coefficient, Indicates the current excess air volume.

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