Structure and method for preventing surge of magnetic suspension centrifugal blower

Abstract

The invention relates to a structure and method for preventing surge of a magnetic suspension centrifugal blower, and relates to the technical field of centrifugal blowers, the structure comprises a fan installed in a cabinet, a diffuser pipe is arranged at the output end of the fan, and a pressure sensor is used for detecting the pressure at the outlet of the diffuser pipe; the side face of the diffuser pipe is communicated with an emptying branch, and an emptying valve is arranged on the emptying branch. A PLC control panel is installed on the side face of the machine cabinet, an anti-surge calculation module is arranged in the PLC control panel, the anti-surge calculation module judges whether the draught fan reaches the surge critical or not, part of allowance is reserved for a surge value, a program acts on the critical state, damage caused by surge to the draught fan is avoided to the maximum extent, two sets of draught fan surge preventing schemes are arranged, and the draught fan is prevented from being damaged by surge. And according to the pressure allowance reserved in the corresponding program of the anti-surge calculation module, the motor is controlled to increase the rotating speed or the air release valve is controlled to act, and the use requirement for preventing fan surge is met.

Description

Technical Field

[0001] The invention relates to the technical field of centrifugal blowers, and in particular to a structure and a method for preventing a magnetically suspended centrifugal blower from surging. Background Art

[0002] When the magnetic levitation centrifugal blower is running, if the pressure fluctuation at the inlet and outlet changes to a certain extent, surge will occur, accompanied by strong noise and vibration, which will lead to a significant decline in the performance of the magnetic levitation centrifugal blower. Not only that, if the surge becomes more serious, the magnetic bearing of the magnetic levitation centrifugal blower will become unstable, resulting in serious consequences such as collision between the rotor and stator components.

[0003] To prevent magnetic levitation centrifugal blowers from surging, different manufacturers have adopted different methods. Basically, they all monitor the pressure at the blower outlet or the vibration of the blower to determine whether the blower is currently in a surge state. When the blower enters a surge state, the venting device in the blower outlet pipe is controlled to discharge the gas to reduce the pressure at the outlet, thereby preventing the blower from surging. This preventive plan has a certain lag. From the sensor detecting the surge to the start of venting, and then to the outlet pressure dropping to the normal range, the entire process is completed. The blower may have been surging for a while, and the reliability of this plan is not high in the event of a sudden power outage.

[0004] The existing solutions cannot meet the needs of preventing surge in magnetic levitation blowers. In addition, since the current magnetic levitation drum speed is as high as tens of thousands of revolutions, if surge occurs and the vibration value of the equipment reaches a certain level, the motor rotor will become unstable and fall, causing serious damage to the stator part of the fan and the magnetic levitation motor. In order to reduce damage to the fan components, an effective method for preventing surge in magnetic levitation blowers and a supporting structure are needed. Summary of the invention

[0005] In order to improve the problem of surge occurring during operation of the magnetic levitation blower in the above-mentioned background technology, the present invention provides a structure and method for preventing surge of the magnetic levitation centrifugal blower.

[0006] The present invention provides a structure and method for preventing a magnetic suspension centrifugal blower from surging, and adopts the following technical solutions: A structure for preventing a magnetically suspended centrifugal blower from surging comprises a fan installed in a cabinet, wherein a rotor and a speed sensor are arranged inside the fan, the rotor is driven by a motor, a diffuser is arranged at an output end of the fan, a pressure sensor is arranged at an outlet of the diffuser, a side of the diffuser is connected to a venting branch and a vent valve is arranged on the venting branch; a PLC control panel is installed on the side of the cabinet, the PLC control panel has an anti-surge calculation module built in, a receiving end of the PLC control panel receives a pressure signal of the pressure sensor and a speed signal of the speed sensor, and controls the action of the motor or the vent valve according to the pressure margin reserved in the corresponding program of the anti-surge calculation module.

[0007] Preferably, the vent valve includes a vent tee, a cylinder and a solenoid valve arranged on the vent branch, the cylinder is installed at the first output port of the vent tee, the solenoid valve is arranged on one side of the cylinder body and is communicatively connected with the sending end of the PLC control panel to control the cylinder output end to move in the vent tee, and open or block the second output port of the vent tee.

[0008] A method for preventing a magnetically suspended centrifugal blower from surging, using a structure for preventing a magnetically suspended centrifugal blower from surging, comprising the following steps: Step 1: Install the fan and various components in the cabinet; Step 2: Use a pressure sensor to detect the pressure signal at the outlet of the diffuser, and transmit the response to the cylinder and the anti-surge calculation module. The anti-surge calculation module determines whether the fan reaches the surge criticality. The fan surge criticality is set at a critical state with a reserved pressure margin. Step 3: Use the speed sensor to detect whether the fan has reached the set maximum speed; Step 4: When the fan runs at a speed that does not reach the set maximum speed and reaches the surge threshold, the anti-surge calculation module controls the motor to increase the speed according to the program, and the fan runs stably; Step 5: The fan runs at the set maximum speed. When it reaches the surge critical point, the cylinder operates according to the reserved pressure margin in the corresponding program of the anti-surge calculation module. The excess gas is quickly discharged on the venting branch, and the fan runs stably.

[0009] Preferably, in step two, by analyzing and calculating multiple sets of flow and pressure data at different motor speeds, a nearly smooth curve is obtained, thereby inferring the flow and outlet pressure corresponding to when surge occurs at different speeds of the fan, thereby reserving a pressure margin under the critical state.

[0010] Preferably, the reserved pressure margin accounts for 3%-5% of the total pressure.

[0011] Preferably, the fan power is 50kW and the maximum speed is set to 40000rpm; In summary, the present invention has the following beneficial technical effects: 1. Compared with the existing measures, the method for preventing fan surge in the present invention is different in program setting. The traditional anti-surge process takes effect when the fan surge is detected. It takes too long from surge to venting and then to pressure reduction. The method for preventing fan surge in the present invention is to divide the surge into critical values, leave some margin for the surge value, and operate the program in a critical state, which can not only shorten the venting reaction time, but also avoid the damage of the fan caused by surge to the greatest extent, thereby increasing the service life of the fan.

[0012] 2. The present invention is equipped with two sets of solutions for preventing fan surge in view of different fan speed conditions. One is that the fan is operated at a speed that has not reached the set maximum speed, and surge is prevented by increasing the fan speed. The other is that the fan is operated at the set maximum speed, and the fan is prevented from entering a surge state by emptying the vent branch, thereby meeting the need for preventing fan surge. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a schematic structural diagram of a structure for preventing a magnetically suspended centrifugal blower from surging according to an embodiment of the present invention; Figure 2 The present invention is a flowchart of a method for preventing a magnetically suspended centrifugal blower from surging.

[0014] Explanation of the reference numerals in the accompanying drawings: 1. Cabinet; 2. Fan; 3. Rotor; 4. Speed ​​sensor; 5. Motor; 6. Diffuser; 7. Pressure sensor; 8. Vent branch; 9. Vent valve; 10. PLC control panel; 11. Anti-surge calculation module; 12. Vent tee; 13. Cylinder; 14. Solenoid valve. DETAILED DESCRIPTION

[0015] The following combination Figure 1-Figure 2 The present invention is described in further detail.

[0016] The embodiment of the invention discloses a structure and a method for preventing a magnetic suspension centrifugal blower from surging.

[0017] Reference Figure 1A structure for preventing a magnetically suspended centrifugal blower from surging comprises a fan 2 installed in a cabinet 1, a rotor 3 and a speed sensor 4 for detecting the speed of the rotor 3 being arranged inside the fan 2, the rotor 3 being driven by a motor 5, the rotor 3 driving an impeller to blow air and output, a diffuser 6 being arranged at the output end of the fan 2, a pressure sensor 7 being arranged at the outlet of the diffuser 6, a venting branch 8 being connected to the side of the diffuser 6 and a venting valve 9 being arranged on the venting branch 8; a PLC control panel 10 being installed at the side of the cabinet 1, the PLC control panel 10 being equipped with an anti-surge calculation module 11, a receiving end of the PLC control panel 10 receiving a pressure signal of the pressure sensor 7 and a speed signal of the speed sensor 4, and controlling the action of the motor 5 or the venting valve 9 according to the pressure margin reserved in the corresponding program of the anti-surge calculation module 11.

[0018] Reference Figure 1 The vent valve 9 includes a vent tee 12, a cylinder 13 and a solenoid valve 14 arranged on the vent branch 8. The cylinder 13 is installed at the first output port of the vent tee 12. The solenoid valve 14 is arranged on one side of the cylinder body of the cylinder 13 and is communicatively connected with the sending end of the PLC control panel 10 to control the output end of the cylinder 13 to move in the vent tee 12 to open or block the second output port of the vent tee 12.

[0019] The vent valve 9 utilizes the wind pressure at the fan outlet and does not require additional air and electricity supply. During normal operation, the high-pressure gas output by the diffuser pipe 6 supplies the cylinder 13, and the piston inside the cylinder 13 pushes and blocks the second output port of the vent tee 12. When the PLC control panel 10 controls the venting, the solenoid valve 14 receives the electrical signal output by the sending end of the PLC control panel 10, and the solenoid valve 14 is actuated to achieve reversal, so that the air pressure in the cylinder 13 is the same as that in the atmosphere. Therefore, the high-pressure gas output by the diffuser pipe 6 pushes the piston back, and the second output port of the vent tee 12 is opened. The vent valve 9 is controlled by the PLC control panel 10 and can be opened and closed quickly. Before surge occurs, the venting and pressure relief can be achieved within 0.5 seconds. During a power outage, it can still be opened quickly to effectively protect the fan 2.

[0020] Among them, the piston and corresponding sealing material can withstand temperatures of -60°C to 200°C. They will not harden or break due to long-term temperature changes and do not require regular replacement. The cylinder body of cylinder 13 is made of hard anodized aluminum alloy, which has excellent durability, heat resistance and reliability.

[0021] Reference Figure 1 , Figure 2 A method for preventing a magnetically suspended centrifugal blower from surging, using a structure for preventing a magnetically suspended centrifugal blower from surging, comprising the following steps: Step 1: Install the fan 2 and various components in the cabinet 1; Step 2: Use the pressure sensor 7 to detect the pressure signal at the outlet of the diffuser pipe 6, and transmit the response to the cylinder 13 and the anti-surge calculation module 11. The anti-surge calculation module 11 determines whether the fan 2 reaches the surge critical state. The surge critical state is set under the critical state with a reserved pressure margin. In step 2, by analyzing and calculating multiple sets of flow and pressure data at different speeds of the motor 5, a curve close to smoothness is obtained, thereby calculating the flow and outlet pressure corresponding to the surge of the fan 2 at different speeds, thereby reserving a pressure margin under the critical state; The reserved pressure margin accounts for 3%-5% of the total pressure. The measure of reserved pressure margin for surge criticality can not only shorten the venting reaction time, but also avoid the damage of fan 2 caused by surge to the greatest extent, and increase the service life of fan 2.

[0022] Step 3: Use the speed sensor 4 to detect whether the fan 2 has reached the set maximum speed; the fan 2 power is 50kW, and the set maximum speed is 40000rpm; Step 4: When the fan 2 runs at a speed that does not reach the set maximum speed and reaches the surge critical point, the anti-surge calculation module 11 controls the motor 5 to increase the speed of the rotor 3 according to the program, and the fan 2 runs stably; Step 5: The fan 2 runs at the set maximum speed. When it reaches the surge critical point, the cylinder 13 operates according to the pressure margin reserved in the corresponding program of the anti-surge calculation module 11, and the excess gas is quickly discharged on the venting branch 8, and the fan 2 runs stably.

[0023] In the actual anti-surge test of the fan, multiple groups of data are tested, and the test data are sorted and converted into a flow fitting curve formula to calculate the flow. When the motor 5 is at 95% speed, the flow fitting curve formula is Y=-56X²+170X-100, where X is the pressure ratio of the outlet pressure to the inlet pressure when the fan 2 surges, and Y is the flow corresponding to the fan 2 surge. In the actual anti-surge test of the fan, the actual measured speed and pressure were recorded, and the following data were obtained: adiabatic coefficient 1.4, gas constant 288j / kgK, inlet pressure 100.2kPa, outlet pressure 196.8kPa, inlet temperature 41.4 degrees Celsius, outlet temperature 130.8 degrees Celsius, speed 38000rpm, maximum operating frequency 633Hz, impeller diameter 0.186m, and polytropic efficiency for calculation 0.77; The surge formula is calculated by analyzing the above data, which involves three anti-surge bases A, D, and M. A=0.50729, D=2273*[(P2 / P1)^2]*(273.15+t1) / H^2, m=0.37106, where P1 is the inlet pressure (kPa), P2 is the outlet pressure (kPa), t1 is the inlet temperature (degrees Celsius), and H is the motor operating frequency (Hz); when the fan is running, when D>A, the gas is vented to prevent surge.

[0024] The implementation principle of a structure for preventing a magnetically suspended centrifugal blower from surging in an embodiment of the present invention is as follows: during the operation of the fan 2, the pressure at its outlet increases due to external force factors. At this time, the fan 2 is about to surge. The pressure sensor 7 arranged at the outlet of the diffuser 6 detects the pressure signal and transmits the pressure signal to the cylinder 13 and the anti-surge calculation module 11. The cylinder 13 will quickly act during the consumption of the pressure margin reserved in the corresponding program of the anti-surge calculation module 11. The corresponding program of the anti-surge calculation module 11 is equipped with two sets of designs for dealing with the surge of the fan 2, which act on the critical state where the reserved pressure margin exists. If the fan 2 is running without reaching the set maximum speed, if surge is about to occur, the corresponding program of the anti-surge calculation module 11 will take effect, and the motor 5 will be controlled to increase the speed of the rotor 3 to deal with the surge situation; if the fan 2 is running at the set maximum speed, if surge is about to occur, the pressure at the outlet of the diffuser 6 will be reduced by the venting branch 8, and the excess gas will be quickly vented on the venting branch 8, thereby avoiding damage to the fan 2 caused by surge.

[0025] The above are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A structure for preventing a magnetically suspended centrifugal blower from surging, comprising a fan (2) installed in a cabinet (1), wherein a rotor (3) and a speed sensor (4) are arranged inside the fan (2), and wherein the rotor (3) is driven by a motor (5), and wherein: The output end of the fan (2) is provided with a pressure diffuser (6), the outlet of the pressure diffuser (6) is provided with a pressure sensor (7), the side of the pressure diffuser (6) is connected to a vent branch (8), and a vent valve (9) is provided on the vent branch (8); A PLC control panel (10) is installed on the side of the cabinet (1), and an anti-surge calculation module (11) is built into the PLC control panel (10). A receiving end of the PLC control panel (10) receives a pressure signal from a pressure sensor (7) and a speed signal from a speed sensor (4), and controls the action of the motor (5) or the vent valve (9) according to a pressure margin reserved in a corresponding program of the anti-surge calculation module (11).

2. The structure for preventing a magnetically suspended centrifugal blower from surging according to claim 1, characterized in that: The vent valve (9) comprises a vent tee (12) arranged on the vent branch (8), a cylinder (13) and a solenoid valve (14), wherein the cylinder (13) is installed at a first output port of the vent tee (12), and the solenoid valve (14) is arranged at one side of a cylinder body of the cylinder 13 and is communicatively connected to a transmitting end of a PLC control panel (10), so as to control the output end of the cylinder (13) to move in the vent tee (12) and to open or block a second output port of the vent tee (12).

3. A method for preventing a magnetic levitation centrifugal blower from surging, using any one of the structures for preventing a magnetic levitation centrifugal blower from surging as claimed in claims 1-2, characterized in that: The following steps are involved: Step 1: Install the fan (2) and various components in the cabinet (1); Step 2: Use the pressure sensor (7) to detect the pressure signal at the outlet of the diffuser (6), and transmit the response to the cylinder (13) and the anti-surge calculation module (11). The anti-surge calculation module (11) determines whether the fan (2) reaches the surge threshold. The surge threshold is set at a critical state with a reserved pressure margin. Step 3: Use the speed sensor (4) to detect whether the fan (2) has reached the set maximum speed; Step 4: When the fan (2) runs at a speed that does not reach the set maximum speed and reaches the surge threshold, the anti-surge calculation module (11) controls the motor (5) to increase the speed in accordance with the program, so that the fan (2) runs stably; Step 5: The fan (2) operates at a set maximum speed. When the surge critical speed is reached, the cylinder (13) operates according to the reserved pressure margin in the corresponding program of the anti-surge calculation module (11), and the excess gas is quickly discharged on the discharge branch (8), and the fan (2) operates stably.

4. A method for preventing surging of a magnetic suspension centrifugal blower according to claim 3, characterized in that: In step 2, by analyzing and calculating multiple sets of flow and pressure data at different speeds of the motor (5), a curve close to smoothness is obtained, thereby inferring the flow and outlet pressure corresponding to the occurrence of surge of the fan (2) at different speeds, thereby reserving a pressure margin under the critical state.

5. A method for preventing surging of a magnetic suspension centrifugal blower according to claim 4, characterized in that: The reserved pressure margin accounts for 3%-5% of the total pressure.

6. A method for preventing surging of a magnetic suspension centrifugal blower according to claim 3, characterized in that: In step 3, the power of the fan (2) is 50 kW, and the maximum speed is set to 40,000 rpm.

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