A control method for a waste heat recovery system of a centrifugal compressor

Abstract

The application discloses a kind of control method of centrifugal compressor waste heat recovery system, it belongs to waste heat recovery field, specific steps are: the temperature detection of two output medium, water inlet pipeline is equipped with electric control valve, control unit is equipped with one outlet water temperature set value and one outlet gas temperature set value, control unit can obtain the difference ΔW of outlet water actual value and set value and the difference ΔA of outlet gas actual value and set value;When ΔA is greater than outlet gas difference upper limit value, ΔW according to outlet water upper limit value and outlet water lower limit value, electric control valve opening degree increases;When ΔA is greater than outlet gas difference lower limit value and less than outlet gas difference upper limit value, ΔW according to outlet water upper limit value and outlet water lower limit value, electric control valve opening degree is unchanged or electric control valve opening degree reduces;When ΔA is less than outlet gas difference lower limit value, ΔW according to outlet water upper limit value and outlet water lower limit value, electric control valve opening degree is unchanged or electric control valve opening degree reduces, to be able to simultaneously quickly make corresponding minimum adjustment to the outlet water temperature and exhaust temperature of compressor.

Description

Technical Field

[0001] This invention relates to the field of waste heat recovery, and specifically to a control method for a centrifugal compressor waste heat recovery system. Background Technology

[0002] Centrifugal compressors are commonly used air compression equipment in industrial production. While achieving efficient gas compression, they generate a large amount of heat. In order to recover and utilize this heat, centrifugal compression systems are often equipped with waste heat recovery systems.

[0003] Specifically, centrifuges utilize interstage coolers to release the heat of air compression. Cooling water absorbs this heat and its temperature rises after passing through the cooler. This heat is then transferred to the application end via a heat exchanger or to a cooling tower via a heat exchanger plate. Existing preheating recovery systems face the problem of unstable outlet water and air temperatures, negatively impacting both the air-consuming and heat-consuming ends.

[0004] To address the problems existing in the prior art, this invention designs and manufactures a control method for a centrifugal compressor waste heat recovery system to overcome the aforementioned deficiencies. Summary of the Invention

[0005] To address the problems existing in the prior art, the present invention provides a control method for a centrifugal compressor waste heat recovery system, which can simultaneously and quickly make corresponding minimum adjustments to the compressor's outlet water temperature and exhaust temperature.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A control method for a waste heat recovery system of a centrifugal compressor, the system comprising a centrifugal compressor, an inlet pipe, an outlet pipe, a water inlet pipe, a water outlet pipe, and a control unit, wherein the centrifugal compressor has a heat exchanger, the high-temperature gas generated by the centrifugal compressor enters the heat exchanger through the inlet pipe and is then discharged through the outlet pipe, and the cooling water enters the heat exchanger through the water inlet pipe and is then discharged through the water outlet pipe;

[0008] The water inlet pipe is equipped with an electrically controlled valve, and the control unit adjusts the water inlet flow rate of the water inlet pipe by adjusting the opening degree of the electrically controlled valve;

[0009] It also includes a water outlet temperature sensor and an exhaust temperature sensor, both of which are electrically connected to the control unit. The water outlet temperature sensor is installed on the water outlet pipe to detect the temperature of the discharged water, and the exhaust temperature sensor is installed on the exhaust pipe to detect the temperature of the discharged air.

[0010] The specific steps of the control method are as follows:

[0011] S1. The water outlet temperature sensor and the exhaust temperature sensor respectively acquire the temperature TW1 of the water discharged from the water outlet pipe and the temperature TA1 of the gas discharged from the exhaust pipe;

[0012] S2. The control unit has an outlet water temperature setpoint TW0, and the control unit can obtain the difference ΔW(TW1-TW0) between TW1 and TW0;

[0013] The control unit has an outlet temperature setpoint TA0, and the control unit can obtain the difference ΔA(TA1-TA0) between TA1 and TA0;

[0014] S3. Multiple preset control thresholds are set for the difference value ΔW, which divides the outlet water temperature into multiple temperature zones, including an upper limit value and a lower limit value for the outlet water difference;

[0015] The preset control threshold for the difference ΔA is set to multiple values, which divides the outlet temperature into multiple temperature zones, including an upper limit value and a lower limit value for the outlet difference.

[0016] When ΔA is greater than the upper limit of the gas outlet difference, the opening degree of the electric control valve increases according to the upper and lower limits of the water outlet.

[0017] When ΔA is greater than the lower limit of the gas outlet difference and less than the upper limit of the gas outlet difference, then ΔW will either keep the opening of the solenoid valve unchanged or decrease the opening of the solenoid valve according to the upper limit and lower limit of the water outlet.

[0018] When ΔA is less than the lower limit of the gas outlet difference, then ΔW will either remain unchanged or decrease depending on the upper and lower limits of the water outlet.

[0019] Preferably, the preset control thresholds for ΔW are A2, A1, X, C1, and C2, where A2 > A1 > X > C1 > C2. The upper limit of the outlet water difference is selected from one of A2, A1, X, and C1, and the lower limit of the outlet water difference is selected from one that is less than the upper limit of the outlet water difference.

[0020] The preset control thresholds for ΔA are B2, B1, Y, D1, and D2, where B2 > B1 > Y > D1 > D2; the upper limit of the gas outlet difference is selected from one of B2, B1, Y, and D1, and the lower limit of the gas outlet difference is selected from one that is less than the upper limit of the gas outlet difference.

[0021] Preferably, the greater the deviation of ΔA from the upper limit and / or the greater the deviation of ΔW from the lower limit, the greater the rate at which the electrically controlled valve opens.

[0022] Preferably, the difference ΔW is set with an upper limit A and a lower limit X, the difference ΔA is set with an upper limit B and a lower limit Y, and the initial state of the electric control valve is 100% fully open.

[0023] When ΔW≤X and ΔA<Y, the opening degree of the electrically controlled valve decreases;

[0024] When ΔW≤X and Y≤ΔA<B, the opening degree of the electrically controlled valve decreases;

[0025] When ΔW≤X and ΔA≥B, the opening degree of the electrically controlled valve increases;

[0026] When X < ΔW ≤ A and ΔA < Y, the opening degree of the electrically controlled valve remains unchanged;

[0027] When X < ΔW ≤ A and Y ≤ ΔA < B, the opening degree of the electrically controlled valve remains unchanged;

[0028] When X < ΔW ≤ A and ΔA ≥ B, the opening degree of the electrically controlled valve increases;

[0029] When ΔW > A and ΔA < Y, the opening degree of the electrically controlled valve remains unchanged;

[0030] When ΔW>A and Y≤ΔA<B, the opening degree of the electrically controlled valve remains unchanged;

[0031] When ΔW>A and ΔA≥B, the opening degree of the electrically controlled valve increases.

[0032] Preferably, the outlet water temperature setting value TW0 is set to 50℃.

[0033] Preferably, the outlet temperature setting value TA0 is set to 40℃.

[0034] Preferably, the lower limit value X of ΔW is set to 0, and the lower limit value Y of ΔA is set to 0.

[0035] Preferably, the upper limit value A of ΔW is set to 2-8, and the upper limit value B of ΔA is set to 2-8.

[0036] Preferably, when ΔW≤X, the solenoid valve opens or closes at a rate of a% / second based on the change in the difference ΔA.

[0037] When X < ΔW ≤ A, the electrically controlled valve opens at a rate of b% / second according to the change in the difference ΔA.

[0038] When ΔW > A, the solenoid valve opens at a rate of c% / second according to the change in the difference ΔA.

[0039] The value of c is greater than the value of b.

[0040] Preferably, the values ​​of a, b, and c are between 0.5 and 3.

[0041] The advantages of this invention are:

[0042] This invention has two inputs (low-temperature water and low-temperature gas) and two outputs (heated water and heated gas). These outputs can only be controlled by the flow rate of the low-temperature water. Because the inputs and outputs are not linear, and even when the flow rate of the low-temperature water is controlled, the time lag between the inputs and outputs is significant, the adjustment speed is slow. This invention simultaneously detects the temperature of the media at both outputs and rationally adjusts the opening of the electronically controlled valve based on the data relationship between them, minimizing the adjustment amount while ensuring adjustment speed. Attached Figure Description

[0043] Figure 1 A schematic diagram of the relevant structures connected to the centrifugal compressor;

[0044] Figure 2 This is a schematic diagram of the structure related to the connection between the present invention and the control unit.

[0045] In the diagram: 1-Centrifugal compressor, 2-Heat exchanger, 3-Inlet pipe, 4-Outlet pipe, 5-Inlet water pipe, 6-Outlet water pipe, 7-Exhaust temperature sensor, 8-Outlet water temperature sensor, 9-Electrical control valve, 10-Control unit. Detailed Implementation

[0046] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0047] like Figure 1 , Figure 2 As shown, a control method for a centrifugal compressor waste heat recovery system is disclosed. The centrifugal compressor waste heat recovery system includes a centrifugal compressor 1, an inlet pipe 3, an outlet pipe 4, a water inlet pipe 5, a water outlet pipe 6, and a control unit 10. The centrifugal compressor 1 has a heat exchanger 2. The high-temperature gas generated by the centrifugal compressor 1 enters the heat exchanger 2 through the inlet pipe 3 and is then discharged through the outlet pipe 4. Cooling water enters the heat exchanger 2 through the water inlet pipe 5 and is then discharged through the water outlet pipe 6. The above structure is a common structure of centrifugal compressor 1 with waste heat recovery, and will not be described in detail here.

[0048] The water inlet pipe 5 of this invention is equipped with an electric control valve 9, and the control unit 10 adjusts the water inlet flow rate of the water inlet pipe 5 by adjusting the opening degree of the electric control valve 9;

[0049] It also includes a water outlet temperature sensor 8 and an exhaust temperature sensor 7. Both the water outlet temperature sensor 8 and the exhaust temperature sensor 7 are electrically connected to the control unit 10. The water outlet temperature sensor 8 is installed on the water outlet pipe 6 to detect the temperature of the discharged water, and the exhaust temperature sensor 7 is installed on the exhaust pipe 4 to detect the temperature of the discharged air.

[0050] This invention has two inputs (low-temperature water and low-temperature gas) entering from the air inlet pipe 3 and the water inlet pipe 5 respectively, and two outputs (heated water and heated gas) exiting from the air outlet pipe 4 and the water outlet pipe 6 respectively. However, these outputs can only be controlled by the flow rate of the low-temperature water. Because the input and output are not linear, and even with controlled flow rate, the time lag between the input and output is significant, the adjustment speed is slow. This invention simultaneously uses the outlet water temperature sensor 8 and the exhaust temperature sensor 7 to detect the temperature of the media at both outputs, and rationally adjusts the opening of the electronically controlled valve 9 based on the data relationship between them, minimizing the adjustment amount while ensuring adjustment speed.

[0051] The specific steps of the control method for the waste heat recovery system of a centrifugal compressor are as follows:

[0052] S1. The water outlet temperature sensor 8 and the exhaust temperature sensor 7 respectively acquire the temperature TW1 of the water discharged from the water outlet pipe 6 and the temperature TA1 of the gas discharged from the exhaust pipe 4;

[0053] S2. The control unit 10 has an outlet water temperature setpoint TW0, which is preferably set to 50°C. The control unit 10 can obtain the difference ΔW(TW1-TW0) between TW1 and TW0.

[0054] The control unit 10 has an outlet temperature setpoint TA0, which is preferably set to 40°C. The control unit 10 can obtain the difference ΔA(TA1-TA0) between TA1 and TA0.

[0055] S3. Multiple preset control thresholds are set for the difference value ΔW, which divides the outlet water temperature into multiple temperature zones, including an upper limit value and a lower limit value for the outlet water difference;

[0056] The preset control threshold for the difference ΔA is set to multiple values, which divides the outlet temperature into multiple temperature zones, including an upper limit value and a lower limit value for the outlet difference.

[0057] When ΔA is greater than the upper limit of the gas outlet difference, then ΔW increases the opening degree of the electric control valve 9 according to the upper and lower limits of the water outlet.

[0058] When ΔA is greater than the lower limit of the gas outlet difference and less than the upper limit of the gas outlet difference, then ΔW will either remain unchanged or decrease the opening of the solenoid valve 9 according to the upper and lower limits of the water outlet.

[0059] When ΔA is less than the lower limit of the gas outlet difference, then ΔW will either remain unchanged or decrease depending on the upper and lower limits of the water outlet.

[0060] The centrifugal compressor 1 of the present invention has a heat exchanger 2 and is also connected to an intake pipe 3. The high-temperature gas generated by the centrifugal compressor 1 enters the heat exchanger 2 through the intake pipe 3 and is then discharged through the outlet pipe 4. Cooling water enters the heat exchanger 2 through the water inlet pipe 5 and is then discharged through the water outlet pipe 5.

[0061] Because the centrifugal compressor has two inputs (low-temperature water and low-temperature gas) entering from the inlet pipe 3 and the water inlet pipe 5 respectively, and two outputs (heated water and heated gas) discharging from the outlet pipe 4 and the water outlet pipe 6 respectively, these two outputs can only be controlled by the flow rate of the low-temperature water. Since the input and output are not linear, and even if the flow rate of the low-temperature water is controlled, the time lag with the output is significant, resulting in slow adjustment speed. This invention simultaneously uses the outlet water temperature sensor 8 and the exhaust temperature sensor 7 to detect the temperature of the media at both outputs, and rationally adjusts the opening of the electronically controlled valve 9 based on the data relationship between the two sensors, minimizing the adjustment amount while ensuring adjustment speed.

[0062] Specifically, the preset control thresholds for ΔW in this invention are A2, A1, X, C1, and C2, where A2 > A1 > X > C1 > C2. The upper limit of the water outlet difference is selected from one of A2, A1, X, and C1, and the lower limit of the water outlet difference is selected from one less than the upper limit of the water outlet difference. The preset control thresholds for ΔA are B2, B1, Y, D1, and D2, where B2 > B1 > Y > D1 > D2. The upper limit of the gas outlet difference is selected from one of B2, B1, Y, and D1, and the lower limit of the gas outlet difference is selected from one less than the upper limit of the gas outlet difference.

[0063] In this invention, the initial state of the electrically controlled valve 9 is 100% fully open. The difference ΔW is set with an upper limit value A and a lower limit value X, and the difference ΔA is set with an upper limit value B and a lower limit value Y.

[0064] When ΔW≤X and ΔA<Y, the opening degree of the solenoid valve 9 decreases;

[0065] When ΔW≤X and Y≤ΔA<B, the opening degree of the solenoid valve 9 decreases;

[0066] When ΔW≤X and ΔA≥B, the opening degree of the solenoid valve 9 increases;

[0067] When X < ΔW ≤ A and ΔA < Y, the opening degree of the solenoid valve 9 remains unchanged;

[0068] When X < ΔW ≤ A and Y ≤ ΔA < B, the opening degree of the solenoid valve 9 remains unchanged;

[0069] When X < ΔW ≤ A and ΔA ≥ B, the opening degree of the solenoid valve 9 increases;

[0070] When ΔW > A and ΔA < Y, the opening degree of the solenoid valve 9 remains unchanged;

[0071] When ΔW>A and Y≤ΔA<B, the opening degree of the solenoid valve 9 remains unchanged;

[0072] When ΔW>A and ΔA≥B, the opening degree of the solenoid valve 9 increases.

[0073] The lower limit X of ΔW is set to 0, the lower limit Y of ΔA is set to 0, the upper limit A of ΔW is set to 2-8, for example 2, 3, 4, 5, 6, 7, 8, and the upper limit B of ΔA is set to 2-8, for example 2, 3, 4, 5, 6, 7, 8.

[0074] To further improve the adjustment speed, when ΔW≤X, the solenoid valve 9 opens or closes at a% / second based on the change in the difference ΔA; when X<ΔW≤A, the solenoid valve 9 opens at b% / second based on the change in the difference ΔA; when ΔW>A, the solenoid valve 9 opens at c% / second based on the change in the difference ΔA, where c > b. Specifically, the values ​​of a, b, and c range from 0.5 to 3, for example, 0.5, 1, 1.5, 2, 2.5, and 3. The greater the deviation of ΔA from the upper limit and / or the greater the deviation of ΔW from the lower limit, the greater the opening rate of the solenoid valve 9.

[0075] The specific working methods are as follows:

[0076]

[0077]

[0078] It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the invention. Furthermore, it should be understood that after reading the technical description of this invention, those skilled in the art can make various alterations, modifications, and / or variations to the invention, and all such equivalent forms also fall within the scope of protection defined by the appended claims.

Claims

1. A control method for a waste heat recovery system of a centrifugal compressor, characterized in that, The system includes a centrifugal compressor, an inlet pipe, an outlet pipe, a water inlet pipe, a water outlet pipe, and a control unit. The centrifugal compressor has a heat exchanger. The high-temperature gas generated by the centrifugal compressor enters the heat exchanger through the inlet pipe and is then discharged through the outlet pipe. Cooling water enters the heat exchanger through the water inlet pipe and is then discharged through the water outlet pipe. The water inlet pipe is equipped with an electrically controlled valve, and the control unit adjusts the water inlet flow rate of the water inlet pipe by adjusting the opening degree of the electrically controlled valve; It also includes a water outlet temperature sensor and an exhaust temperature sensor, both of which are electrically connected to the control unit. The water outlet temperature sensor is installed on the water outlet pipe to detect the temperature of the discharged water, and the exhaust temperature sensor is installed on the exhaust pipe to detect the temperature of the discharged air. The specific steps of the control method are as follows: S1. The water outlet temperature sensor and the exhaust temperature sensor respectively acquire the temperature TW1 of the water discharged from the water outlet pipe and the temperature TA1 of the gas discharged from the exhaust pipe; S2. The control unit has an outlet water temperature setpoint TW0, and the control unit can obtain the difference between TW1 and TW0. , =TW1-TW0; The control unit has an outlet air temperature setpoint TA0, and the control unit can obtain the difference between TA1 and TA0. , =TA1-TA0; S3. Difference The system has multiple preset control thresholds, which divide the outlet water temperature into multiple temperature zones, including an upper limit value and a lower limit value for the outlet water difference. Difference The preset control threshold is set to multiple values, which divides the outlet temperature into multiple temperature zones, including an upper limit value and a lower limit value for the outlet temperature difference. when If it exceeds the upper limit of the air output difference, then The opening degree of the electrically controlled valve increases based on the upper limit and lower limit of the outlet water difference. when If the air difference is greater than the lower limit and less than the upper limit, then Based on the upper limit and lower limit of the outlet water difference, the opening degree of the solenoid valve remains unchanged or decreases. when If it is less than the lower limit of the air output difference, then Based on the upper limit and lower limit of the outlet water difference, the opening degree of the solenoid valve remains unchanged or decreases.

2. The control method for a centrifugal compressor waste heat recovery system according to claim 1, characterized in that, The The preset control thresholds are A2, A1, X, C1, and C2, where A2 > A1 > X > C1 > C2. The upper limit of the outlet water difference is selected from one of A2, A1, X, and C1, and the lower limit of the outlet water difference is selected from one that is less than the upper limit of the outlet water difference. The The preset control thresholds are B2, B1, Y, D1, and D2, where B2 > B1 > Y > D1 > D2; the upper limit of the gas outlet difference is selected from one of B2, B1, Y, and D1, and the lower limit of the gas outlet difference is selected from one that is less than the upper limit of the gas outlet difference.

3. The control method for a centrifugal compressor waste heat recovery system according to claim 2, characterized in that, when The greater the deviation from the upper limit of the exhaust gas difference value, and / or, The greater the deviation from the lower limit of the outlet water difference, the greater the rate at which the electrically controlled valve opens.

4. The control method for a centrifugal compressor waste heat recovery system according to claim 3, characterized in that, Difference Define an upper limit value A and a lower limit value X, and the difference between them. Set an upper limit value B and a lower limit value Y, and the initial state of the electric control valve is 100% fully open; when ≤X, and <Y, the opening degree of the electrically controlled valve decreases; when ≤X, and Y≤ <B, the opening degree of the electrically controlled valve decreases; when ≤X, and ≥B, the opening degree of the electrically controlled valve increases; When X < ≤A, and <Y, the opening degree of the electrically controlled valve remains unchanged; When X < ≤A, and Y≤ <B, the opening degree of the electrically controlled valve remains unchanged; When X < ≤A, and ≥B, the opening degree of the electrically controlled valve increases; when >A, and <Y, the opening degree of the electrically controlled valve remains unchanged; when >A, and Y≤ <B, the opening degree of the electrically controlled valve remains unchanged; when >A, and ≥B, the opening degree of the electrically controlled valve increases.

5. The control method for a centrifugal compressor waste heat recovery system according to claim 1, characterized in that, The outlet water temperature setting value TW0 is set to 50℃.

6. The control method for a centrifugal compressor waste heat recovery system according to claim 1, characterized in that, The outlet air temperature setting value TA0 is set to 40℃.

7. The control method for a centrifugal compressor waste heat recovery system according to claim 5, characterized in that, The The lower limit value X is set to 0℃. The lower limit value Y is set to 0℃.

8. The control method for a centrifugal compressor waste heat recovery system according to claim 5, characterized in that, The The upper limit value A is set to 2-8℃, the The upper limit B is set to 2-8℃.

9. The control method for a centrifugal compressor waste heat recovery system according to claim 4, characterized in that, when ≤X, the electronically controlled valve operates based on the difference. The change in the valve's opening or closing speed is a% / second. When X < ≤A, the electronically controlled valve operates based on the difference. The change in the valve causes the electrically controlled valve to open at a rate of b% / second. when >A, the electronically controlled valve operates based on the difference. The change in the valve's opening speed is c% / second. c value > b value.

10. A control method for a centrifugal compressor waste heat recovery system according to claim 9, characterized in that, The values ​​of a, b, and c range from 0.5 to 3.

Images