Dry oil-free screw compressor two-stage exhaust temperature control method, system, electronic device and storage medium

Abstract

This invention discloses a method, system, electronic equipment, and storage medium for controlling the secondary exhaust temperature of a dry oil-free screw compressor. The temperature control method includes: Step S1, cooling the high-temperature compressed air discharged after the secondary compression of the dry oil-free screw compressor in a cooler, and then sending it to a gas-liquid separator for gas-liquid separation; Step S2, guiding the condensate precipitated at the bottom of the gas-liquid separator to the secondary air inlet of the dry oil-free screw compressor through a spray pipe, and installing an electric proportional regulating valve and a spraying device on the spray pipe; Step S3, monitoring the liquid level in the gas-liquid separator in real time and adjusting the opening of the electric proportional regulating valve according to the liquid level signal; Step S4, uniformly spraying the condensate into the secondary air inlet through the spraying device to mix with the air entering the secondary compression chamber, thereby reducing the temperature rise during the secondary compression process and stabilizing the secondary exhaust temperature at the set value. This invention can improve resource utilization, save energy and reduce consumption, has high stability, and improve work efficiency.

Description

Technical Field

[0001] This invention belongs to the field of compressor technology, and relates to a dry oil-free screw compressor, and more particularly to a method, system, electronic equipment and storage medium for controlling the secondary exhaust temperature of a dry oil-free screw compressor. Background Technology

[0002] Dry-type oil-free screw compressors produce 100% oil-free compressed air because there is no lubricating oil inside the compression chamber. They are widely used in industries such as food, pharmaceuticals, electronics, and precision instruments. These compressors typically employ two-stage compression, with an interstage cooler to reduce the secondary intake air temperature. However, the temperature rise during the secondary compression process is still significant. If the exhaust temperature is too high, it not only increases energy consumption and reduces volumetric efficiency but may also lead to rotor thermal deformation, seal failure, and other malfunctions.

[0003] Currently, the main methods for controlling the secondary exhaust temperature include: increasing the heat exchange area of ​​the interstage cooler, using variable frequency fans to regulate the cooling airflow, or injecting liquid cooling medium into the compression chamber. Liquid injection cooling is direct and responsive, but for oil-free compressors, oil injection will disrupt the oil-free characteristics, while water injection requires addressing issues such as water supply, water volume control, and vaporization uniformity. Existing technologies include solutions using external water sources injected via metering pumps, but this increases system complexity and operating costs; others directly discharge the condensate from the interstage cooler, resulting in resource waste. Furthermore, directly adjusting the water injection valve opening is susceptible to fluctuations in inlet water pressure, leading to unstable water volume and large exhaust temperature fluctuations. Excessive water injection may also cause liquid slugging or entrainment of liquid water into the compression chamber, reducing compression efficiency.

[0004] In view of this, there is an urgent need to design a new dry oil-free screw compressor in order to overcome at least some of the aforementioned defects of existing dry oil-free screw compressors. Summary of the Invention

[0005] This invention provides a method, system, electronic equipment, and storage medium for controlling the secondary exhaust temperature of a dry oil-free screw compressor, which can improve resource utilization, save energy and reduce consumption, have high stability, and improve work efficiency.

[0006] To solve the above-mentioned technical problems, according to one aspect of the present invention, the following technical solution is adopted: A method for controlling the secondary discharge temperature of a dry oil-free screw compressor, the temperature control method comprising: Step S1: The high-temperature compressed air discharged after the two-stage compression of the dry oil-free screw compressor is cooled by a cooler and then sent to an air-water separator for air-water separation. Step S2: The condensate separated at the bottom of the gas-water separator is led to the secondary air inlet of the dry oil-free screw compressor through the spray pipeline, and an electric proportional regulating valve and a spray device are installed on the spray pipeline. Step S3: Real-time detection of the liquid level in the gas-liquid separator, and adjustment of the opening of the electric proportional regulating valve according to the liquid level signal, so that the condensate liquid level in the gas-liquid separator is maintained within the preset range. Step S4: The condensate is evenly sprayed into the secondary air inlet by the spraying device and mixed with the air entering the secondary compression chamber to reduce the temperature rise during the secondary compression process and stabilize the secondary exhaust temperature at the set value.

[0007] As one embodiment of the present invention, the exhaust temperature control method further includes an exhaust temperature mathematical model construction step, which involves constructing an exhaust temperature mathematical model. The exhaust temperature mathematical model construction step specifically includes: preprocessing the data in the training dataset; extracting features from the preprocessed data to identify key features; then combining, statistically analyzing, and grouping the extracted key features; standardizing and normalizing the key features to form a key feature combination; the key feature combination includes liquid level data in the gas-liquid separator, opening data of the electric proportional control valve, secondary exhaust temperature data, liquid level threshold range data in the gas-liquid separator, and secondary exhaust temperature threshold range data; and constructing the exhaust temperature mathematical model based on the formed key feature combination.

[0008] In step S3, the obtained liquid level data in the gas-liquid separator, the liquid level threshold range data in the gas-liquid separator, and the secondary exhaust temperature threshold range data are input into the exhaust temperature mathematical model to obtain the opening data of the electric proportional control valve.

[0009] The key feature combination also includes control effect data corresponding to the opening data of the electric proportional control valve. The control effect data includes the change in liquid level data and the change in secondary exhaust temperature data in the gas-liquid separator per unit time under the corresponding opening data of the electric proportional control valve. This facilitates comparison of whether the liquid level data and the secondary exhaust temperature data have deviated from the corresponding threshold. If they have deviated, the opening data of the electric proportional control valve is adjusted to make the liquid level data and the secondary exhaust temperature data more stable.

[0010] As one embodiment of the present invention, the temperature control method further includes step S5: real-time detection of the secondary exhaust temperature, and correction of the liquid level setting value of the gas-water separator according to the exhaust temperature deviation: when the exhaust temperature is higher than the target value, the liquid level setting value is reduced; when the exhaust temperature is lower than the target value, the liquid level setting value is increased.

[0011] In one embodiment of the present invention, in step S3, the liquid level detection adopts a continuous liquid level sensor, outputs a 4-20mA standard analog signal, and performs closed-loop control of the electric proportional regulating valve through a dedicated PID controller.

[0012] In one embodiment of the present invention, the spraying device is an atomizing nozzle, which is installed at the central axis of the secondary air intake pipe, and the spraying direction is perpendicular to the airflow direction, so as to achieve uniform mixing of condensate and intake air.

[0013] In one embodiment of the present invention, an anti-vortex device is provided at the bottom outlet of the gas-water separator. The anti-vortex device is a cross baffle or a conical guide structure to prevent compressed air from being sucked into the spray pipe.

[0014] As one embodiment of the present invention, the spray pipe is also provided with a one-way valve to prevent the airflow from the secondary air inlet from flowing back into the spray pipe.

[0015] In one embodiment of the present invention, the cooler is an air-cooled or water-cooled heat exchanger, whose cooling capacity ensures that the temperature of the cooled compressed air is lower than the dew point temperature at the corresponding pressure, so as to ensure that sufficient condensate is released in the gas-water separator.

[0016] As one embodiment of the present invention, the preset range is 30% to 70% of the total volume of the gas-water separator, so as to avoid insufficient water spraying due to excessively high liquid level or water carryover in gas due to excessively low liquid level.

[0017] As one embodiment of the present invention, the electric proportional regulating valve adopts an equal percentage flow characteristic, has good regulation accuracy at a small opening, and the valve body is made of stainless steel or engineering plastic to adapt to the weak corrosiveness of condensate.

[0018] According to another aspect of the present invention, the following technical solution is adopted: a two-stage exhaust temperature control system for a dry oil-free screw compressor, the temperature control system comprising: a control circuit, a cooler, a gas-water separator, a liquid level sensing unit, a temperature sensing unit, a proportional regulating valve, and a spray device; The control circuit is connected to the cooler, the gas-water separator, the liquid level sensing unit, the temperature sensing unit, the proportional regulating valve, and the spray device, respectively. The cooler is connected to the gas-liquid separator. The high-temperature compressed airflow discharged from the dry oil-free screw compressor after two-stage compression is cooled by the cooler and then sent to the gas-liquid separator for gas-liquid separation. The condensate separated by the gas-water separator is led to the secondary air inlet of the dry oil-free screw compressor through a spray pipeline; a proportional regulating valve and a spray device are installed on the spray pipeline. The liquid level sensing unit is installed in the gas-liquid separator to detect the liquid level data in the gas-liquid separator and send the detected liquid level data to the control circuit; the temperature sensing unit is used to sense the secondary exhaust temperature and send the sensed data to the control circuit. The spraying device evenly sprays condensed water into the secondary air inlet, mixing it with the airflow entering the secondary compression chamber to reduce the temperature rise during the secondary compression process. The control circuit maintains the condensate level in the gas-water separator within a preset range based on the liquid level data and the opening of the proportional control valve, while simultaneously stabilizing the secondary exhaust temperature at the set value.

[0019] As one embodiment of the present invention, the exhaust temperature control system further includes an exhaust temperature mathematical model construction module, which is used to construct an exhaust temperature mathematical model. The exhaust temperature mathematical model construction module preprocesses the data in the exhaust training dataset; it extracts key features from the preprocessed data; then it combines, statistically analyzes, and groups the extracted key features, and standardizes and normalizes the key features to form a key feature combination; the key feature combination includes liquid level data in the gas-liquid separator, opening data of the electric proportional control valve, secondary exhaust temperature data, liquid level threshold range data in the gas-liquid separator, and secondary exhaust temperature threshold range data; and constructs an exhaust temperature mathematical model based on the formed key feature combination. The control circuit inputs the acquired liquid level data in the gas-water separator, the liquid level threshold range data in the gas-water separator, and the secondary exhaust temperature threshold range data into the exhaust temperature mathematical model to obtain the opening data of the electric proportional regulating valve, and uses this to control the operation of the spray device.

[0020] The key feature combination also includes control effect data corresponding to the opening data of the electric proportional control valve. The control effect data includes the change in liquid level data and the change in secondary exhaust temperature data in the gas-liquid separator per unit time under the corresponding opening data of the electric proportional control valve. This facilitates comparison of whether the liquid level data and the secondary exhaust temperature data have deviated from the corresponding threshold. If they have deviated, the opening data of the electric proportional control valve is adjusted to make the liquid level data and the secondary exhaust temperature data more stable.

[0021] In one embodiment of the present invention, the spraying device is an atomizing nozzle, which is installed at the central axis of the secondary air intake pipe, and the spraying direction is perpendicular to the airflow direction, so as to achieve uniform mixing of condensate and intake air.

[0022] An anti-vortex device is installed at the bottom outlet of the gas-water separator. The anti-vortex device is a cross baffle or a conical guide structure to prevent compressed air from being sucked into the spray pipe.

[0023] The spray pipe is also equipped with a one-way valve to prevent the airflow from the secondary air inlet from flowing back into the spray pipe.

[0024] The control circuit monitors the secondary exhaust temperature in real time and corrects the liquid level setpoint of the gas-water separator according to the exhaust temperature deviation: when the exhaust temperature is higher than the target value, the liquid level setpoint is lowered; when the exhaust temperature is lower than the target value, the liquid level setpoint is raised.

[0025] The cooler is an air-cooled or water-cooled heat exchanger, whose cooling capacity ensures that the temperature of the cooled compressed air is lower than the dew point temperature at the corresponding pressure, so as to ensure that sufficient condensate is released from the gas-water separator.

[0026] The preset range is 30% to 70% of the total volume of the gas-water separator to avoid insufficient water spraying due to excessively high liquid level or water carryover in the gas due to excessively low liquid level.

[0027] The electric proportional control valve adopts an equal percentage flow characteristic, has good adjustment accuracy at small openings, and the valve body is made of stainless steel or engineering plastic to adapt to the weak corrosiveness of condensate.

[0028] According to another aspect of the present invention, the following technical solution is adopted: an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the above method.

[0029] According to another aspect of the present invention, the following technical solution is adopted: a storage medium storing computer program instructions thereon, which, when executed by a processor, implement the steps of the above-described method.

[0030] The beneficial effects of this invention are as follows: the method, system, electronic equipment and storage medium for controlling the two-stage exhaust temperature of the dry oil-free screw compressor proposed in this invention can improve resource utilization, save energy and reduce consumption, have high stability and improve work efficiency.

[0031] (1) Resource recycling and energy saving: The condensate originally discharged is collected and sprayed back to the secondary air inlet, eliminating the need for an external water source and reducing system operating costs. At the same time, the latent heat of vaporization of water is used to remove the heat of compression, effectively reducing the exhaust temperature and improving the compression efficiency.

[0032] (2) Liquid level-flow self-balancing control with high stability: By maintaining the liquid level of the gas-water separator, the spray flow rate is automatically equal to the condensate production water flow rate. The spray volume changes synchronously with the compressor load. There is no need for complex flow measurement and control equipment. The control is simple and has strong anti-disturbance ability, and the exhaust temperature fluctuation is small.

[0033] (3) Uniform spraying to avoid efficiency loss: The atomizing nozzle and anti-vortex and anti-backflow design ensure that the water sprayed into the secondary intake is uniform and fine water droplets, rather than a gas-liquid two-phase flow with gas entrainment, thus avoiding the impact of gas short circuit on compression efficiency and improving the specific power of the whole machine.

[0034] (4) High scalability: By introducing exhaust temperature feedback to correct the liquid level setpoint, a cascade control system can be constructed to further improve the temperature control accuracy and meet higher process requirements.

[0035] (5) Low modification cost and wide applicability: This invention can be directly modified on existing dry oil-free screw compressors. Only a liquid level sensor, electric proportional regulating valve and simple pipeline are needed to achieve precise control of exhaust temperature, which has extremely high engineering promotion value. Attached Figure Description

[0036] Figure 1 This is a flowchart of a two-stage exhaust temperature control method for a dry oil-free screw compressor according to an embodiment of the present invention.

[0037] Figure 2 This is a schematic diagram of the composition of a two-stage exhaust temperature control system for a dry oil-free screw compressor in one embodiment of the present invention.

[0038] Figure 3 This is a schematic diagram of the composition of an electronic device according to an embodiment of the present invention.

[0039] The attached diagram is labeled as follows: 1-Secondary compressor main unit; 2-Secondary exhaust pipe; 3-Cooler; 4-Gas-water separator; 5-Level sensor; 6-Controller; 7-Electric proportional regulating valve; 8-Spray pipe; 9-Atomizing nozzle; 10-Secondary intake pipe; 11-Anti-vortex device; 12-One-way valve; 13-Temperature sensor. Detailed Implementation

[0040] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0041] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0042] The description in this section pertains to only a few typical embodiments, and the present invention is not limited to the scope of the embodiments described. Substitution of identical or similar prior art methods with some technical features in the embodiments is also within the scope of the description and protection of this invention.

[0043] The steps described in the various embodiments in the specification are for ease of explanation only, and the implementation of this application is not limited by the order of the steps.

[0044] The term "connection" in the specification includes both direct and indirect connections, such as connections made through active devices, passive devices, or electrical conduction media; it may also include connections made by other active or passive devices that are known to those skilled in the art and can achieve the same or similar functional purpose, such as connections made through circuits or components such as switches or follower circuits.

[0045] This invention discloses a method for controlling the two-stage exhaust temperature of a dry oil-free screw compressor. Figure 1 This is a flowchart of a two-stage exhaust temperature control method for a dry oil-free screw compressor according to an embodiment of the present invention; please refer to [link / reference]. Figure 1 The temperature control method includes:

Step S1

[0046] The cooler is an air-cooled or water-cooled heat exchanger, whose cooling capacity ensures that the temperature of the cooled compressed air is lower than the dew point temperature at the corresponding pressure, so as to ensure that sufficient condensate is released from the gas-water separator.

[0047] In one embodiment of the present invention, the preset range is 30% to 70% of the total volume of the gas-water separator, so as to avoid insufficient water spraying due to excessively high liquid level or water carryover in gas due to excessively low liquid level.

[0048]

Step S2

[0049] The spraying device is an atomizing nozzle installed at the central axis of the secondary air intake pipe, with the spraying direction perpendicular to the airflow direction to achieve uniform mixing of condensate and intake air. In one embodiment, the spraying pipe is also equipped with a one-way valve to prevent backflow of airflow from the secondary air intake into the spraying pipe.

[0050]

Step S3

[0051]

Step S4

[0052] In one embodiment of the present invention, the temperature control method further includes step S5: real-time detection of the secondary exhaust temperature, and correction of the liquid level setting value of the gas-water separator according to the exhaust temperature deviation: when the exhaust temperature is higher than the target value, the liquid level setting value is reduced; when the exhaust temperature is lower than the target value, the liquid level setting value is increased.

[0053] Furthermore, in one embodiment of the present invention, the exhaust temperature control method further includes an exhaust temperature mathematical model construction step, which constructs an exhaust temperature mathematical model. The exhaust temperature mathematical model construction step specifically includes: preprocessing the data in the training dataset; extracting features from the preprocessed data to extract key features; then combining, statistically analyzing, and grouping the extracted key features, standardizing and normalizing the key features to form a key feature combination; the key feature combination includes liquid level data in the gas-liquid separator, opening data of the electric proportional control valve, secondary exhaust temperature data, liquid level threshold range data in the gas-liquid separator, and secondary exhaust temperature threshold range data; and constructing the exhaust temperature mathematical model based on the formed key feature combination.

[0054] In one embodiment, in step S3, the obtained liquid level data in the gas-liquid separator, the liquid level threshold range data in the gas-liquid separator, and the secondary exhaust temperature threshold range data can be input into the exhaust temperature mathematical model to obtain the opening degree data of the electric proportional control valve.

[0055] Furthermore, the key feature combination may also include control effect data corresponding to the opening data of the electric proportional control valve. This control effect data includes the change in liquid level and secondary exhaust temperature within the gas-liquid separator per unit time under the corresponding opening data. This facilitates comparison of whether the liquid level and secondary exhaust temperature data have deviated from their corresponding thresholds. If a deviation is found, the liquid level and secondary exhaust temperature data can be stabilized by adjusting the opening data of the electric proportional control valve. This improvement further enhances the stability of the system operation.

[0056] This invention further discloses a two-stage exhaust temperature control system for a dry oil-free screw compressor. Figure 2 This is a schematic diagram of the composition of a two-stage exhaust temperature control system for a dry oil-free screw compressor according to an embodiment of the present invention; please refer to [link / reference]. Figure 2 The temperature control system includes: a control circuit, a cooler 3, a gas-water separator 4, a liquid level sensing unit 5, a temperature sensing unit 13, an electric proportional regulating valve 7, and a spray device (which may be an atomizing nozzle 9).

[0057] The control circuit is connected to the cooler, gas-liquid separator, liquid level sensing unit, temperature sensing unit, proportional control valve, and spray device. The cooler is connected to the gas-liquid separator. The high-temperature compressed gas flow discharged from the dry oil-free screw compressor after two-stage compression is cooled by the cooler and then sent to the gas-liquid separator for gas-liquid separation. The condensate separated by the gas-liquid separator is led to the secondary air inlet of the dry oil-free screw compressor through a spray pipeline; a proportional control valve and a spray device are installed on the spray pipeline.

[0058] The liquid level sensing unit is installed in the gas-liquid separator to detect the liquid level data within the separator and send the detected data to the control circuit. The temperature sensing unit senses the secondary exhaust temperature and sends the sensed data to the control circuit. The spray device evenly sprays condensate into the secondary air inlet, mixing it with the airflow entering the secondary compression chamber to reduce the temperature rise during the secondary compression process. The control circuit maintains the condensate level in the gas-liquid separator within a preset range and stabilizes the secondary exhaust temperature at a set value based on the liquid level data and the opening of the proportional control valve.

[0059] In one embodiment of the present invention, the spraying device is an atomizing nozzle, which is installed at the central axis of the secondary air intake pipe, and the spraying direction is perpendicular to the airflow direction to achieve uniform mixing of condensate and intake air.

[0060] The gas-liquid separator is equipped with an anti-vortex device at its bottom outlet. This anti-vortex device is a cross-shaped baffle or a conical guide structure to prevent compressed air from being drawn into the spray pipe. A one-way valve is also installed on the spray pipe to prevent backflow of air from the secondary air inlet into the spray pipe. The control circuit monitors the secondary exhaust temperature in real time and corrects the liquid level setpoint of the gas-liquid separator based on the exhaust temperature deviation: when the exhaust temperature is higher than the target value, the liquid level setpoint is lowered; when the exhaust temperature is lower than the target value, the liquid level setpoint is raised.

[0061] The cooler is an air-cooled or water-cooled heat exchanger, whose cooling capacity ensures that the temperature of the cooled compressed air is lower than the dew point temperature at the corresponding pressure, thus guaranteeing sufficient condensate precipitation in the gas-water separator. The preset range is 30% to 70% of the total volume of the gas-water separator to avoid insufficient water spray due to excessively high liquid level or water carryover in the gas due to excessively low liquid level. The electric proportional regulating valve 7 can adopt an equal percentage flow characteristic, providing good adjustment accuracy at small openings, and the valve body is made of stainless steel or engineering plastic to adapt to the mild corrosiveness of condensate.

[0062] In one embodiment of the present invention, the exhaust temperature control system further includes an exhaust temperature mathematical model building module, which is used to build an exhaust temperature mathematical model.

[0063] The exhaust temperature mathematical model construction module preprocesses the data in the exhaust training dataset; extracts key features from the preprocessed data; then combines, statistically analyzes, and groups the extracted key features, standardizes and normalizes the key features to form a key feature combination; the key feature combination includes liquid level data in the gas-liquid separator, opening data of the electric proportional control valve, secondary exhaust temperature data, liquid level threshold range data in the gas-liquid separator, and secondary exhaust temperature threshold range data; and constructs an exhaust temperature mathematical model based on the formed key feature combination.

[0064] The control circuit inputs the acquired liquid level data in the gas-water separator, the liquid level threshold range data in the gas-water separator, and the secondary exhaust temperature threshold range data into the exhaust temperature mathematical model to obtain the opening data of the electric proportional regulating valve, and uses this to control the operation of the spray device.

[0065] The key feature combination also includes control effect data corresponding to the opening data of the electric proportional control valve. This control effect data includes the change in liquid level and secondary exhaust temperature within the gas-liquid separator per unit time under the corresponding opening data. This facilitates comparison of whether the liquid level and secondary exhaust temperature data have deviated from their corresponding thresholds. If a deviation is found, the opening data of the electric proportional control valve is adjusted to stabilize the liquid level and secondary exhaust temperature data. This improvement further enhances the stability of the system operation. Example 1

[0066] This invention discloses a method for two-stage exhaust temperature control of a dry oil-free screw compressor. Figure 2 This is a schematic diagram of the composition of a two-stage exhaust temperature control system for a dry oil-free screw compressor according to an embodiment of the present invention; please refer to [link / reference]. Figure 2In one embodiment of the present invention, the present invention can be applied to a certain model of 450kW dry oil-free screw compressor; the compressor has a rated discharge pressure of 0.8MPa and a secondary rated discharge temperature design value of ≤110℃.

[0067] System Composition: High-temperature compressed air discharged from the secondary compressor 1 enters the water-cooled (or air-cooled) cooler 3 via the secondary exhaust pipe 2. After cooling, the temperature drops to approximately 45℃ (corresponding to a dew point temperature of approximately 50℃ at a pressure of 0.25MPa, ensuring supercooling), and then enters the air-water separator 4. The air-water separator 4 is a cyclone type with an effective volume of 30L and an anti-vortex device 11 (cross baffle) at the bottom. A hydrostatic level sensor 5 (range 0~800mm, output 4-20mA) is installed on the side wall of the air-water separator 4. The separated condensate is led out from the bottom outlet via the spray pipe 8, which is sequentially equipped with a manual ball valve, an electric proportional regulating valve 7 (interface G1 / 4, flow range 0~2.5L / min, control signal 4-20mA), a one-way valve 12, and an atomizing nozzle 9. The atomizing nozzle 9 is installed at the center of the secondary intake pipe 10, with the spray direction perpendicular to the airflow direction. Controller 6 is a custom-designed controller with a built-in PID control block. It receives signals from level sensor 5 and outputs 4-20mA to the electric proportional control valve 7. A temperature sensor 13 is installed on the secondary exhaust pipe for monitoring and display.

[0068] In one embodiment, the control method of the present invention specifically includes: S1: After the compressor starts, the secondary exhaust is cooled and separated, and the condensate gradually accumulates at the bottom of the gas-water separator 4; S2: When the liquid level is higher than the preset lower limit (e.g., 10% of the total volume, corresponding to a liquid level height of 80mm), the controller 6 automatically enters the PID automatic mode and sets the target liquid level value to 160mm (20% liquid level). S3: The liquid level sensor 5 provides real-time feedback on the liquid level value, and the controller 6 outputs a control signal through PID calculation to adjust the opening of the electric proportional regulating valve 7, so that the liquid level is stabilized within the range of 160±10mm. S4: Condensate is evenly sprayed into the secondary intake through atomizing nozzle 9, and after mixing with air, it enters the secondary compression chamber. The evaporation of water significantly reduces the compression temperature rise. The measured secondary exhaust temperature is stable at around 105℃, which meets the design requirements.

[0069] Running result: Compared with the same model unit that did not adopt this solution, the secondary exhaust temperature dropped from 165℃ to 105℃, the compressor specific power dropped from 6.26kW / (m³ / min) to 6.06kW / (m³ / min), saving about 3.2% of energy, and the condensate is completely recycled and reused without any external discharge.

[0070] Based on Example 1, an exhaust temperature feedback correction function is added. Controller 6 reads the measured value of the secondary exhaust temperature and compares it with the target value of 105℃. The deviation is calculated using PID control to generate a correction amount for the liquid level setpoint. For example, when the exhaust temperature rises to 108℃, the liquid level setpoint is increased from 160mm to 170mm, thereby increasing the water spray volume and suppressing the temperature rise; conversely, the liquid level setpoint is decreased. This scheme achieves complete closed-loop control with exhaust temperature as the final controlled variable, resulting in a higher degree of automation, and is particularly suitable for situations with drastic changes in environmental conditions.

[0071] For compressors with different discharge capacities, an electric proportional control valve with an appropriate diameter can be selected based on the condensate production rate. If the condensate production is extremely low (e.g., <0.1L / min), a miniature electromagnetic proportional valve or a micro-metering pump can be used instead. If there is a risk of freezing during winter shutdowns, a heat tracing device can be added to the gas-liquid separator and spray pipeline. All the above modifications are within the scope of protection of this invention.

[0072] This invention maintains a stable liquid level by detecting the liquid level in the gas-liquid separator and adjusting the opening of the proportional valve, thereby achieving a dynamic balance between the spray water flow rate and the condensate production rate, and thus achieving stable control of the secondary exhaust temperature. The method is simple and reliable, and has significant energy-saving effects and engineering application value.

[0073] This invention also discloses an electronic device, Figure 3 This is a schematic diagram of the composition of an electronic device according to an embodiment of the present invention; please refer to [link / reference]. Figure 3 At the hardware level, the electronic device includes a memory, a processor, and at least one communication interface; the processor may be a microprocessor, and the memory may include main memory, such as random access memory (RAM) or non-volatile memory. Of course, the electronic device may also include other hardware as needed.

[0074] The processor, communication interface, and memory can be interconnected via an internal bus. The memory stores programs (including operating system programs and application programs); the programs may include program code, which may include computer operation instructions. The memory may include main memory and non-volatile memory, and provides instructions and data to the processor.

[0075] In one embodiment, the processor can read the corresponding program from non-volatile memory into memory and then run it; the processor can execute the program stored in memory and specifically perform the following operations (e.g. Figure 1 (as shown)

Step S1

[0076] The cooler is an air-cooled or water-cooled heat exchanger, whose cooling capacity ensures that the temperature of the cooled compressed air is lower than the dew point temperature at the corresponding pressure, so as to ensure that sufficient condensate is released from the gas-water separator.

[0077] In one embodiment of the present invention, the preset range is 30% to 70% of the total volume of the gas-water separator, so as to avoid insufficient water spraying due to excessively high liquid level or water carryover in gas due to excessively low liquid level.

[0078]

Step S2

[0079] The spraying device is an atomizing nozzle installed at the central axis of the secondary air intake pipe, with the spraying direction perpendicular to the airflow direction to achieve uniform mixing of condensate and intake air. In one embodiment, the spraying pipe is also equipped with a one-way valve to prevent backflow of airflow from the secondary air intake into the spraying pipe.

[0080]

Step S3

[0081]

Step S4

[0082] In one embodiment of the present invention, the temperature control method further includes step S5: real-time detection of the secondary exhaust temperature, and correction of the liquid level setting value of the gas-water separator according to the exhaust temperature deviation: when the exhaust temperature is higher than the target value, the liquid level setting value is reduced; when the exhaust temperature is lower than the target value, the liquid level setting value is increased.

[0083] Furthermore, in one embodiment of the present invention, the exhaust temperature control method further includes an exhaust temperature mathematical model construction step, which constructs an exhaust temperature mathematical model. The exhaust temperature mathematical model construction step specifically includes: preprocessing the data in the training dataset; extracting features from the preprocessed data to extract key features; then combining, statistically analyzing, and grouping the extracted key features, standardizing and normalizing the key features to form a key feature combination; the key feature combination includes liquid level data in the gas-liquid separator, opening data of the electric proportional control valve, secondary exhaust temperature data, liquid level threshold range data in the gas-liquid separator, secondary exhaust temperature threshold range data, and spray flow rate data of the spray device; and constructing the exhaust temperature mathematical model based on the formed key feature combination.

[0084] In one embodiment, the acquired liquid level data in the gas-liquid separator, the liquid level threshold range data in the gas-liquid separator, and the secondary exhaust temperature threshold range data can be input into the exhaust temperature mathematical model to obtain the opening degree data of the electric proportional control valve.

[0085] This invention further discloses a storage medium storing computer program instructions, which, when executed by a processor, implement the following steps of the method of this invention (e.g. Figure 1 (as shown)

Step S1

[0086] The cooler is an air-cooled or water-cooled heat exchanger, whose cooling capacity ensures that the temperature of the cooled compressed air is lower than the dew point temperature at the corresponding pressure, so as to ensure that sufficient condensate is released from the gas-water separator.

[0087] In one embodiment of the present invention, the preset range is 30% to 70% of the total volume of the gas-water separator, so as to avoid insufficient water spraying due to excessively high liquid level or water carryover in gas due to excessively low liquid level.

[0088]

Step S2

[0089] The spraying device is an atomizing nozzle installed at the central axis of the secondary air intake pipe, with the spraying direction perpendicular to the airflow direction to achieve uniform mixing of condensate and intake air. In one embodiment, the spraying pipe is also equipped with a one-way valve to prevent backflow of airflow from the secondary air intake into the spraying pipe.

[0090]

Step S3

[0091]

Step S4

[0092] In one embodiment of the present invention, the temperature control method further includes step S5: real-time detection of the secondary exhaust temperature, and correction of the liquid level setting value of the gas-water separator according to the exhaust temperature deviation: when the exhaust temperature is higher than the target value, the liquid level setting value is reduced; when the exhaust temperature is lower than the target value, the liquid level setting value is increased.

[0093] Furthermore, in one embodiment of the present invention, the exhaust temperature control method further includes an exhaust temperature mathematical model construction step, which constructs an exhaust temperature mathematical model. The exhaust temperature mathematical model construction step specifically includes: preprocessing the data in the training dataset; extracting features from the preprocessed data to extract key features; then combining, statistically analyzing, and grouping the extracted key features, standardizing and normalizing the key features to form a key feature combination; the key feature combination includes liquid level data in the gas-liquid separator, opening data of the electric proportional control valve, secondary exhaust temperature data, liquid level threshold range data in the gas-liquid separator, secondary exhaust temperature threshold range data, and spray flow rate data of the spray device; and constructing the exhaust temperature mathematical model based on the formed key feature combination.

[0094] In one embodiment, the acquired liquid level data in the gas-liquid separator, the liquid level threshold range data in the gas-liquid separator, and the secondary exhaust temperature threshold range data can be input into the exhaust temperature mathematical model to obtain the opening degree data of the electric proportional control valve.

[0095] In summary, the method, system, electronic equipment, and storage medium for controlling the secondary exhaust temperature of a dry oil-free screw compressor proposed in this invention can improve resource utilization, save energy and reduce consumption, have high stability, and improve work efficiency.

[0096] (1) Resource recycling and energy saving: The condensate originally discharged is collected and sprayed back to the secondary air inlet, eliminating the need for an external water source and reducing system operating costs. At the same time, the latent heat of vaporization of water is used to remove the heat of compression, effectively reducing the exhaust temperature and improving the compression efficiency.

[0097] (2) Liquid level-flow self-balancing control with high stability: By maintaining the liquid level of the gas-water separator, the spray flow rate is automatically equal to the condensate production water flow rate. The spray volume changes synchronously with the compressor load. There is no need for complex flow measurement and control equipment. The control is simple and has strong anti-disturbance ability, and the exhaust temperature fluctuation is small.

[0098] (3) Uniform spraying to avoid efficiency loss: The atomizing nozzle and anti-vortex and anti-backflow design ensure that the water sprayed into the secondary intake is uniform and fine water droplets, rather than a gas-liquid two-phase flow with gas entrainment, thus avoiding the impact of gas short circuit on compression efficiency and improving the specific power of the whole machine.

[0099] (4) High scalability: By introducing exhaust temperature feedback to correct the liquid level setpoint, a cascade control system can be constructed to further improve the temperature control accuracy and meet higher process requirements.

[0100] (5) Low modification cost and wide applicability: This invention can be directly modified on existing dry oil-free screw compressors. Only a liquid level sensor, electric proportional regulating valve and simple pipeline are needed to achieve precise control of exhaust temperature, which has extremely high engineering promotion value.

[0101] It should be noted that this application can be implemented in software and / or a combination of software and hardware; for example, it can be implemented using an application-specific integrated circuit (ASIC), a general-purpose computer, or any other similar hardware device. In some embodiments, the software program of this application can be executed by a processor to implement the steps or functions described above. Similarly, the software program of this application (including related data structures) can be stored in a computer-readable recording medium; for example, RAM memory, magnetic or optical drives, floppy disks, and similar devices. In addition, some steps or functions of this application can be implemented in hardware; for example, as circuitry that cooperates with a processor to perform the various steps or functions.

[0102] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0103] The description and application of the present invention herein are illustrative and not intended to limit the scope of the invention to the embodiments described above. Effects or advantages involved in the embodiments may not be apparent due to various factors, and the description of effects or advantages is not intended to limit the embodiments. Variations and modifications of the embodiments disclosed herein are possible, and various substitutions and equivalents of the components in the embodiments are well known to those skilled in the art. It should be apparent to those skilled in the art that the invention can be implemented in other forms, structures, arrangements, proportions, and with other components, materials, and parts without departing from the spirit or essential characteristics of the invention. Other variations and modifications can be made to the embodiments disclosed herein without departing from the scope and spirit of the invention.

Claims

1. A method for controlling the secondary exhaust temperature of a dry oil-free screw compressor, characterized in that, The exhaust temperature control method includes: Step S1: After the high-temperature compressed airflow discharged from the two-stage compression of the dry oilless screw compressor is cooled by the cooler, it is sent to the gas-water separator for gas-water separation. Step S2: The condensate separated by the gas-water separator is led to the secondary air inlet of the dry oil-free screw compressor through the spray pipeline, and an electric proportional regulating valve and a spray device are installed on the spray pipeline. Step S3: Real-time detection of the liquid level in the gas-liquid separator, and adjustment of the opening of the electric proportional regulating valve according to the liquid level signal, so that the condensate liquid level in the gas-liquid separator is maintained within the preset range. Step S4: The condensate is evenly sprayed into the secondary air inlet by the spraying device and mixed with the air entering the secondary compression chamber to reduce the temperature rise during the secondary compression process and stabilize the secondary exhaust temperature at the set value.

2. The exhaust temperature control method according to claim 1, characterized in that: The exhaust temperature control method further includes an exhaust temperature mathematical model construction step, which involves constructing an exhaust temperature mathematical model. Specifically, this step includes: preprocessing the data in the exhaust training dataset; extracting features from the preprocessed data to identify key features; then combining, statistically analyzing, and grouping the extracted key features; standardizing and normalizing the key features to form a key feature combination; the key feature combination includes liquid level data in the gas-liquid separator, opening data of the electric proportional control valve, secondary exhaust temperature data, liquid level threshold range data in the gas-liquid separator, and secondary exhaust temperature threshold range data; and constructing the exhaust temperature mathematical model based on the formed key feature combination. In step S3, the obtained liquid level data in the gas-liquid separator, the liquid level threshold range data in the gas-liquid separator, and the secondary exhaust temperature threshold range data are input into the exhaust temperature mathematical model to obtain the opening data of the electric proportional control valve. The key feature combination also includes control effect data corresponding to the opening data of the electric proportional control valve. The control effect data includes the change in liquid level data and the change in secondary exhaust temperature data in the gas-liquid separator per unit time under the corresponding opening data of the electric proportional control valve. This facilitates comparison of whether the liquid level data and the secondary exhaust temperature data have deviated from the corresponding threshold. If they have deviated, the opening data of the electric proportional control valve is adjusted to make the liquid level data and the secondary exhaust temperature data more stable.

3. The exhaust temperature control method according to claim 1, characterized in that: The temperature control method further includes step S5: real-time detection of the secondary exhaust temperature, and correction of the liquid level setpoint of the gas-water separator based on the exhaust temperature deviation: when the exhaust temperature is higher than the target value, the liquid level setpoint is reduced; when the exhaust temperature is lower than the target value, the liquid level setpoint is increased.

4. The exhaust temperature control method according to claim 1, characterized in that: The spraying device is an atomizing nozzle, installed at the central axis of the secondary air intake pipe, with the spraying direction perpendicular to the airflow direction to achieve uniform mixing of condensate and intake air; the spraying pipe is also equipped with a one-way valve to prevent backflow of airflow from the secondary air intake into the spraying pipe. The gas-water separator is equipped with an anti-vortex device at the bottom outlet. The anti-vortex device is a cross baffle or a conical guide structure to prevent compressed air from being sucked into the spray pipe. The cooler is an air-cooled or water-cooled heat exchanger, whose cooling capacity ensures that the temperature of the cooled compressed air is lower than the dew point temperature at the corresponding pressure, so as to ensure that there is a sufficient amount of condensate in the air-water separator. The electric proportional control valve adopts an equal percentage flow characteristic, has good adjustment accuracy at small openings, and the valve body is made of stainless steel or engineering plastic to adapt to the weak corrosiveness of condensate.

5. The exhaust temperature control method according to claim 1, characterized in that: In step S3, the liquid level detection uses a continuous liquid level sensor, which outputs a 4-20mA standard analog signal, and performs closed-loop control of the electric proportional regulating valve through a dedicated PID controller. The preset range is 30% to 70% of the total volume of the gas-water separator to avoid insufficient water spraying due to excessively high liquid level or water carryover in the gas due to excessively low liquid level.

6. A two-stage exhaust temperature control system for a dry oil-free screw compressor, characterized in that, The temperature control system includes: a control circuit, a cooler, a gas-liquid separator, a liquid level sensing unit, a temperature sensing unit, a proportional regulating valve, and a spray device. The control circuit is connected to the cooler, the gas-water separator, the liquid level sensing unit, the temperature sensing unit, the proportional regulating valve, and the spray device, respectively. The cooler is connected to the gas-liquid separator. The high-temperature compressed airflow discharged from the dry oil-free screw compressor after two-stage compression is cooled by the cooler and then sent to the gas-liquid separator for gas-liquid separation. The condensate separated by the gas-water separator is led to the secondary air inlet of the dry oil-free screw compressor through a spray pipeline; a proportional regulating valve and a spray device are installed on the spray pipeline. The liquid level sensing unit is installed in the gas-liquid separator to detect the liquid level data in the gas-liquid separator and send the detected liquid level data to the control circuit; the temperature sensing unit is used to sense the secondary exhaust temperature and send the sensed data to the control circuit. The spraying device evenly sprays condensed water into the secondary air inlet, mixing it with the airflow entering the secondary compression chamber to reduce the temperature rise during the secondary compression process. The control circuit maintains the condensate level in the gas-water separator within a preset range based on the liquid level data and the opening of the proportional control valve, while simultaneously stabilizing the secondary exhaust temperature at the set value.

7. The exhaust temperature control system according to claim 6, characterized in that: The exhaust temperature control system further includes an exhaust temperature mathematical model construction module, which is used to construct an exhaust temperature mathematical model. The exhaust temperature mathematical model construction module preprocesses the data in the exhaust training dataset; it extracts key features from the preprocessed data; then it combines, statistically analyzes, and groups the extracted key features, and standardizes and normalizes the key features to form a key feature combination; the key feature combination includes liquid level data in the gas-liquid separator, opening data of the electric proportional control valve, secondary exhaust temperature data, liquid level threshold range data in the gas-liquid separator, and secondary exhaust temperature threshold range data; and constructs an exhaust temperature mathematical model based on the formed key feature combination. The control circuit inputs the acquired liquid level data in the gas-water separator, the liquid level threshold range data in the gas-water separator, and the secondary exhaust temperature threshold range data into the exhaust temperature mathematical model to obtain the opening data of the electric proportional regulating valve, and uses this to control the operation of the spray device. The key feature combination also includes control effect data corresponding to the opening data of the electric proportional control valve. The control effect data includes the change in liquid level data and the change in secondary exhaust temperature data in the gas-liquid separator per unit time under the corresponding opening data of the electric proportional control valve. This facilitates comparison of whether the liquid level data and the secondary exhaust temperature data have deviated from the corresponding threshold. If they have deviated, the opening data of the electric proportional control valve is adjusted to make the liquid level data and the secondary exhaust temperature data more stable.

8. The exhaust temperature control system according to claim 6, characterized in that: The spraying device is an atomizing nozzle, installed at the central axis of the secondary air intake pipe, with the spraying direction perpendicular to the airflow direction to achieve uniform mixing of condensate and intake air; the spraying pipe is also equipped with a one-way valve to prevent backflow of airflow from the secondary air intake into the spraying pipe. The gas-water separator is equipped with an anti-vortex device at the bottom outlet. The anti-vortex device is a cross baffle or a conical guide structure to prevent compressed air from being sucked into the spray pipe. The control circuit monitors the secondary exhaust temperature in real time and corrects the liquid level setpoint of the gas-liquid separator according to the exhaust temperature deviation: when the exhaust temperature is higher than the target value, the liquid level setpoint is lowered; when the exhaust temperature is lower than the target value, the liquid level setpoint is raised. The cooler is an air-cooled or water-cooled heat exchanger, whose cooling capacity ensures that the temperature of the cooled compressed air is lower than the dew point temperature at the corresponding pressure, so as to ensure that there is a sufficient amount of condensate in the air-water separator. The preset range is 30% to 70% of the total volume of the gas-water separator, in order to avoid insufficient water spraying due to excessively high liquid level or water carryover in gas due to excessively low liquid level. The electric proportional control valve adopts an equal percentage flow characteristic, has good adjustment accuracy at small openings, and the valve body is made of stainless steel or engineering plastic to adapt to the weak corrosiveness of condensate.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 5.

10. A storage medium storing computer program instructions thereon, characterized in that, When executed by a processor, the computer program instructions implement the steps of the method according to any one of claims 1 to 5.

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