Air Compressor Exhaust Temperature Control Method Based on Intake Air Temperature and Humidity

Abstract

The present invention provides a method for controlling the exhaust temperature of an air compressor based on intake air temperature and humidity, which comprises the following steps: consulting a compressed air dew point temperature chart, performing curve fitting on the curves under different intake air humidities to form a plurality of first fitting curves and a plurality of first fitting formulas, and performing curve fitting on the oblique lines under different nominal values to form a plurality of second fitting curves and a plurality of second fitting formulas; selecting a corresponding first fitting formula according to the compressor intake air humidity data, substituting the compression ratio data between the compressor exhaust pressure data and the intake air pressure data into the first fitting formula to calculate the nominal value, selecting a corresponding second fitting formula according to the nominal value, and substituting the intake air temperature data into the second fitting formula to calculate the dew point temperature; collecting the exhaust temperature data at the exhaust end of the compressor, and regulating the temperature at the exhaust end of the compressor through a refrigeration system until the exhaust temperature data reaches the dew point temperature. The present invention only needs to install sensors on the air compressor, the equipment installation is simple, the maintenance is convenient, the transformation cost is low, and the adjustment effect of the exhaust temperature can be stably controlled.

Description

Technical Field

[0001] The present invention relates to the technical field of compressors, and particularly to a method for controlling the exhaust temperature of an air compressor based on intake air temperature and humidity. Background Art

[0002] An air compressor is a mechanical device with a very wide range of uses and has important applications in fields such as machinery, metallurgy, textiles, and food. During the operation of an air compressor, due to energy losses during the compression process, the exhaust temperature of the air compressor will increase and deviate from the normal value range. This not only affects the performance of the air compressor but also increases energy consumption, making the efficiency of the air compressor unable to reach the optimal state.

[0003] To solve this problem, the existing solution is to change the operating conditions of the air compressor. For example, by installing temperature and humidity control devices to adjust the intake air temperature and humidity of the air compressor, and then setting a fixed constant temperature target based on empirical data, and controlling the exhaust temperature by starting and stopping the cooling fan to improve the efficiency of the compression process. However, installing temperature and humidity control devices requires appropriate modification of the air compressor, which not only increases the cost of the equipment but also increases the difficulty of equipment maintenance. Moreover, the exhaust temperature of the air compressor and the intake air temperature and humidity are independent of each other, and their changes cannot be fed back in real time. Therefore, it is difficult to achieve stable control of the adjustment effect, which may lead to fluctuations or even oscillations in the exhaust temperature and cannot ensure that the efficiency reaches the optimal state. Summary of the Invention

[0004] In view of the above situation, the present invention provides a method for controlling the exhaust temperature of an air compressor based on intake air temperature and humidity to solve the problems in the prior art that it is difficult to stably control the adjustment effect of the exhaust temperature, as well as the problems of increasing the cost and maintenance difficulty of the equipment.

[0005] To achieve the above object, the technical solution adopted by the present invention is to provide a method for controlling the exhaust temperature of an air compressor based on intake air temperature and humidity, which includes the following steps:

[0006] Consult the compressed air dew point temperature diagram, perform curve fitting on the curves of nominal value - compression ratio at different intake air humidities to form a plurality of first fitting curves and a plurality of first fitting formulas, and perform curve fitting on the oblique lines of intake air temperature - dew point temperature at different nominal values to form a plurality of second fitting curves and a plurality of second fitting formulas;

[0007] Collect the intake air temperature data and intake air humidity data at the intake end of the compressor and the exhaust pressure data at the exhaust end of the compressor;

[0008] Calculate the compression ratio between the exhaust pressure data and the intake pressure data;

[0009] Select the corresponding first fitting formula according to the intake air humidity data, substitute the compression ratio into the first fitting formula to calculate the nominal value, select the corresponding second fitting formula according to the nominal value, and substitute the intake air temperature data into the second fitting formula to calculate the dew point temperature;

[0010] Collect the exhaust temperature data at the exhaust end of the compressor, and regulate the temperature at the exhaust end of the compressor through the refrigeration system until the exhaust temperature data reaches the dew point temperature.

[0011] Further, select at least any ten first coordinate values on each intake air humidity curve on the compressed air dew point temperature diagram, edit the first coordinate values into an EXCEL table, and draw a first scatter diagram according to the first coordinate values, and add a second-order polynomial trend line to the first scatter diagram for fitting to form a plurality of the first fitting curves and the first fitting formula.

[0012] Further, select at least any two second coordinate values on each nominal value diagonal line on the compressed air dew point temperature diagram, edit the second coordinate values into an EXCEL table, and draw a scatter diagram according to the second coordinate values, and add a second-order polynomial trend line to the second scatter diagram for fitting to form a plurality of the second fitting curves and the second fitting formula.

[0013] Further, the intake air pressure is 0.1 MPa.

[0014] Further, write the plurality of first fitting formulas and the plurality of second fitting formulas into the controller, and collect data through the intake air temperature sensor, intake air humidity sensor, exhaust temperature sensor and exhaust pressure sensor and then transmit the data into the controller for calculation.

[0015] The beneficial effect of the present invention is that a method for controlling the exhaust temperature of an air compressor based on the intake air temperature and humidity of the present invention forms a plurality of first fitting curves and first fitting formulas and a plurality of second fitting curves and a plurality of second fitting formulas by curve fitting of the compressed air dew point temperature diagram, and collects data of the exhaust pressure, intake air temperature and intake air humidity for calculation and substitution to realize automatic query of the dew point temperature, thereby taking this as the ideal exhaust temperature of the compressor, and regulating the exhaust temperature of the compressor to the dew point temperature by controlling the refrigeration system. The present invention only needs to install sensors on the air compressor, the equipment installation is simple, the maintenance is convenient, the transformation cost is low, and the present invention only needs to control the temperature at the exhaust end, and does not need to control the temperature and humidity at the intake end to change the temperature at the exhaust end, so as to stably control the adjustment effect of the exhaust temperature. Description of the Drawings

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0017] Figure 1 It is a step diagram of the air compressor exhaust temperature control method based on intake air temperature and humidity of the present invention.

[0018] Figure 2 It is a schematic connection structure diagram of a compressor, sensors and a controller in the air compressor exhaust temperature control method based on intake air temperature and humidity of the present invention.

[0019] Figure 3 It is a compressed air dew point temperature diagram of the air compressor exhaust temperature control method based on intake air temperature and humidity of the present invention.

[0020] Figure 4 It is a schematic diagram of a first fitting curve and a first fitting formula with an intake humidity of 100% in the air compressor exhaust temperature control method based on intake air temperature and humidity of the present invention.

[0021] Figure 5 It is a schematic diagram of a second fitting curve and a second fitting formula with a nominal value of 54.9854 in the air compressor exhaust temperature control method based on intake air temperature and humidity of the present invention.

[0022] The corresponding relationship between the reference numerals and the components is as follows:

[0023] 11 - Controller; 12 - Intake air temperature sensor; 13 - Intake air humidity sensor; 14 - Exhaust temperature sensor; 15 - Exhaust pressure sensor -; 16 - Screw compressor. Detailed implementation manners

[0024] For the convenience of understanding the present invention, the following will be described in conjunction with the drawings and embodiments.

[0025] Please refer to Figures 1 to 5 , the present invention provides an air compressor exhaust temperature control method based on intake air temperature and humidity, including the following steps:

[0026] S1. Refer to the compressed air dew point temperature diagram, perform curve fitting on the curves of the nominal value - compression ratio under different intake humidities to form a plurality of first fitting curves and a plurality of first fitting formulas, and perform curve fitting on the oblique lines of the intake air temperature - dew point temperature under different nominal values to form a plurality of second fitting curves and a plurality of second fitting formulas;

[0027] S2. Collect the intake air temperature data and intake air humidity data at the intake end of the compressor and the exhaust pressure data at the exhaust end of the compressor;

[0028] S3. Calculate the compression ratio between the exhaust pressure data and the intake pressure data;

[0029] S4. Select the corresponding first fitting formula according to the intake air humidity data, substitute the compression ratio into the first fitting formula to calculate the nominal value, select the corresponding second fitting formula according to the nominal value, and substitute the intake air temperature data into the second fitting formula to calculate the dew point temperature;

[0030] S5. Collect the exhaust temperature data at the exhaust end of the compressor, and regulate the temperature at the exhaust end of the compressor through the refrigeration system until the exhaust temperature data reaches the dew point temperature.

[0031] A further improvement of the air compressor exhaust temperature control method based on intake air temperature and humidity of the present invention is that at least any ten first coordinate values are selected on each intake air humidity curve on the compressed air dew point temperature diagram, the first coordinate values are edited into an EXCEL table, and a first scatter plot is drawn according to the first coordinate values, and a second-order polynomial trend line is added to the first scatter plot for fitting to form a plurality of first fitting curves and first fitting formulas.

[0032] A further improvement of the air compressor exhaust temperature control method based on intake air temperature and humidity of the present invention is that at least any two second coordinate values are selected on each nominal value diagonal line on the compressed air dew point temperature diagram, the second coordinate values are edited into an EXCEL table, and a scatter plot is drawn according to the second coordinate values, and a second-order polynomial trend line is added to the second scatter plot for fitting to form a plurality of second fitting curves and second fitting formulas.

[0033] Further, the intake air pressure is 0.1 MPa.

[0034] Further, a plurality of first fitting formulas and a plurality of second fitting formulas are programmed into the controller, and data is collected through an intake air temperature sensor, an intake air humidity sensor, an exhaust temperature sensor and an exhaust pressure sensor and then transmitted into the controller for calculation.

[0035] Specifically, the controller operates to monitor and measure the process parameters, operating / stopping status, and fault diagnosis of the air compressor. The intake temperature sensor detects the temperature at the intake end of the air compressor, the intake humidity sensor detects the humidity at the intake end of the air compressor, the exhaust temperature sensor detects the temperature at the exhaust end of the air compressor, and the exhaust pressure sensor detects the pressure at the exhaust end of the air compressor. The controller is connected to the intake temperature sensor, the intake humidity sensor, the exhaust temperature sensor, and the exhaust pressure sensor. Based on the detection data of the intake temperature sensor, the intake humidity sensor, and the exhaust pressure sensor, the controller calculates the ideal exhaust temperature of the air compressor through the first fitting formula and the second fitting formula as the constant temperature target, and cools the exhaust end of the air compressor through the refrigeration system until the exhaust temperature drops to the ideal exhaust temperature, and then shuts down the refrigeration system.

[0036] The specific implementation steps of the air compressor exhaust temperature control method based on intake temperature and humidity of the present invention are as follows:

[0037] S10, as Figure 3 shown, according to the compressed air dew point temperature diagram of JB / T6430-2014. When manually using the above chart to check the dew point temperature, first, as Figure 3 shown in the right diagram: different intake humidities correspond to different curves. Under the same intake humidity curve, according to the compression ratio P2 / P1 on the abscissa, the nominal value corresponding to the ordinate can be queried from the figure. Secondly, as Figure 3 shown in the left diagram: different nominal values correspond to different oblique lines. According to the nominal value queried from the right diagram, horizontally compare to the left in the left diagram to find the corresponding oblique line, and finally, according to the intake temperature t1 on the abscissa, query the dew point temperature t3 in the corresponding ordinate.

[0038] Then, first fit the curves of different intake humidities in the Figure 3 right diagram to form the first fitting curve and the first fitting formula under different intake humidities. Specifically, at least any ten first coordinate values (i.e., the data of the compression ratio P2 / P1 on the abscissa and the data of the nominal value on the ordinate) can be selected on each intake humidity curve through the above table-checking method, the first coordinate values are edited into an EXCEL table, and a first scatter plot is drawn according to the first coordinate values, and a second-order polynomial trend line is added to the first scatter plot for fitting to form multiple first fitting curves and first fitting formulas.

[0039] Assume that the intake humidity is 100%, and the corresponding curve is the topmost one in the right diagram, then fit this curve, and the formed first fitting curve is as Figure 4 shown, and the first fitting formula is

[0040] y = -0.1149x 2 +4.6255x + 28.237;

[0041] Note: x is the compression ratio and y is the nominal value;

[0042] That is: Nominal value = -0.1149 * Compression ratio * Compression ratio + 4.6255 * Compression ratio + 28.237;

[0043] Then, substituting the compression ratio into the first fitting formula, the nominal value can be calculated.

[0044] Assume the compression ratio is 7, calculate the nominal value

[0045] = -0.1149 * 7 * 7 + 4.6255 * 7 + 28.237

[0046] = 54.9854.

[0047] Then, fit the oblique lines with different nominal values in the left graph of Figure 3 to form the second fitting curves and the second fitting formula under different nominal values. Specifically, at least any two second coordinate values (i.e., the abscissa is the intake air temperature t1 and the ordinate is the dew point temperature t3) can be selected on each nominal value oblique line through the above table lookup method, and the second coordinate values are edited into an EXCEL table, and a scatter plot is drawn based on the second coordinate values, and a second-order polynomial trend line or a linear trend line is added to the second scatter plot for fitting to form multiple second fitting curves and the second fitting formula.

[0048] If the oblique line with a nominal value of 54.9854 is fitted, the formed second fitting curve graph is as shown in Figure 5 shown, and the second fitting formula is

[0049] y = 1.3068x + 28.863;

[0050] Note: x is the intake air temperature and y is the dew point temperature;

[0051] That is, Dew point temperature = 1.3068 * Intake air temperature + 28.863.

[0052] Substitute the actually measured intake air temperature of the compressor into the second fitting formula, and the dew point temperature can be calculated.

[0053] Assume the intake air temperature is 30°C, calculate the dew point temperature

[0054] = 1.3068 * 30 + 28.863

[0055] = 68.067°C.

[0056] Finally, write the above multiple first fitting formulas and multiple second fitting formulas into the controller program.

[0057] S20. When the air compressor 16 operates, the controller 11 collects the data of the intake air temperature sensor 12, the intake air humidity sensor 13, the exhaust air temperature sensor 14 and the exhaust air pressure sensor 15, as Figure 2 shown;

[0058] S30. The controller 11 then calculates the compression ratio between the exhaust air pressure and the intake air pressure, that is, compression ratio = exhaust air pressure / intake air pressure, where the intake air pressure is 0.1 MPa;

[0059] S40. The controller selects the corresponding first fitting formula according to the intake air humidity, substitutes the compression ratio into the first fitting formula to calculate the nominal value, selects the corresponding second fitting formula according to the nominal value, and substitutes the intake air temperature into the second fitting formula to calculate the dew point temperature;

[0060] If it is assumed that the intake air humidity is 100%, the compression ratio is 7, and the intake air temperature is 30 °C, then select Figure 4 the fitting curve and its corresponding fitting formula therein, substitute the compression ratio into the fitting formula, and the calculated nominal value is 54.9854; select Figure 5 the fitting curve and its fitting formula therein according to the nominal value, substitute the intake air temperature into the above formula, and the calculated dew point temperature is 68.067 °C.

[0061] S50. Take the calculated dew point temperature as the ideal exhaust air temperature of the air compressor, as the constant temperature target, and compare it with the collected actual exhaust air temperature. If the actual exhaust air temperature is greater than the dew point temperature, the controller controls the refrigeration system to cool the exhaust end of the compressor to reduce the exhaust air temperature to the dew point temperature, and then turns off the refrigeration system.

[0062] According to the compressed air dew point temperature diagram of JB / T6430-2014, the present invention fits to form the first fitting curve and formula about the nominal value - compression ratio under different intake air humidities, and the second fitting curve and formula about the intake air temperature - dew point temperature under different nominal values. Select the corresponding first fitting formula according to the measured intake air humidity of the compressor, substitute the compression ratio of the exhaust air pressure and the intake air pressure into it, and the nominal value can be obtained. Then select the corresponding second fitting formula according to the nominal value, substitute the measured intake air temperature of the compressor into it, and the dew point temperature can be obtained. Take the dew point temperature as the ideal exhaust air temperature of the compressor, and control the refrigeration system to cool the exhaust air temperature of the compressor until it reaches the dew point temperature.

[0063] The present invention processes the data collected on the intake air temperature, intake air humidity, and exhaust pressure, and substitutes them into the first fitting formula and the second fitting formula to calculate the dew point temperature, realizing the automatic query of the compressed air dew point temperature diagram. The results are more accurate, intelligent, fast, and less error-prone. Finally, the exhaust temperature of the actual compressor is adjusted according to the dew point temperature to reduce it to the dew point temperature, and the control effect on the compressor exhaust temperature is stable.

[0064] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments by using the disclosed technical content within the scope of the technical solution of the present invention. However, as long as the content does not depart from the technical solution of the present invention, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for controlling the exhaust temperature of an air compressor based on intake air temperature and humidity, characterized in that: The following steps are involved: Refer to the compressed air dew point temperature diagram, perform curve fitting on the curve of nominal value-compression ratio under different intake air humidity to form multiple first fitting curves and multiple first fitting formulas, and perform curve fitting on the slope of intake air temperature-dew point temperature under different nominal values ​​to form multiple second fitting curves and multiple second fitting formulas; Collecting intake air temperature data and intake air humidity data of the compressor intake end and exhaust air pressure data of the compressor exhaust end; Calculating a compression ratio between the exhaust pressure data and the intake pressure data; Selecting a first fitting formula corresponding to the intake air humidity data, and substituting the compression ratio into the first fitting formula to calculate a nominal value, selecting a second fitting formula corresponding to the nominal value, and substituting the intake air temperature data into the second fitting formula to calculate a dew point temperature; The exhaust temperature data of the exhaust end of the compressor is collected, and the temperature of the exhaust end of the compressor is regulated by a refrigeration system until the exhaust temperature data reaches the dew point temperature.

2. The air compressor exhaust temperature control method based on intake air temperature and humidity according to claim 1, characterized in that: Select the first coordinate values ​​of at least ten points on each intake humidity curve on the compressed air dew point temperature diagram, edit the first coordinate values ​​into an EXCEL table, draw a first scatter plot based on the first coordinate values, add a second-order polynomial trend line to the first scatter plot for fitting, so as to form multiple first fitting curves and the first fitting formula.

3. The air compressor exhaust temperature control method based on intake air temperature and humidity according to claim 1, characterized in that: Select the second coordinate values ​​of at least two points on each nominal value oblique line on the compressed air dew point temperature graph, edit the second coordinate values ​​into an EXCEL table, draw a second scatter plot based on the second coordinate values, add a second-order polynomial trend line to the second scatter plot for fitting, so as to form a plurality of the second fitting curves and the second fitting formula.

4. The air compressor exhaust temperature control method based on intake air temperature and humidity according to claim 1, characterized in that: The intake pressure is 0.1 MPa.

5. The air compressor exhaust temperature control method based on intake air temperature and humidity according to claim 1, characterized in that: The plurality of first fitting formulas and the plurality of second fitting formulas are programmed into the controller, and data are collected through an intake temperature sensor, an intake humidity sensor, an exhaust temperature sensor and an exhaust pressure sensor and then transmitted to the controller for calculation.

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