KR102141888B1 - pump efficiency measuring method - Google Patents

Abstract

In the pump efficiency calculation method of the present invention, the output torque of the motor is detected without changing the design of the pump, and the output torque of the motor detected by applying the method can be used to increase the accuracy of the pump efficiency calculation. In the process of manufacturing, pump installation, pump commissioning, and pump maintenance, the efficiency of the pump as well as the state of the motor can be accurately determined, so that the user can accurately determine the maintenance timing of the motor and pump.

Description

Pump efficiency measuring method

The present invention relates to a method for calculating the pump efficiency, in particular, the output torque of the pump motor by the resistance value of the pump motor winding, the instantaneous voltage value and the instantaneous current value supplied to the pump motor, and the rotational speed mounted on the motor rotation shaft or the pump rotation shaft. It relates to a pump efficiency calculation method that can calculate the correct pump efficiency by calculating the axial power of the actual pump motor in the operation of the pump by the rotational speed of the pump motor detected by the sensor.

Most of the pumps are driven by a motor, and are selected and used according to the type of fluid to be used, flow rate, and pumping head.

The user should use a suitable pump according to the performance or energy efficiency of the pump.

The pump efficiency (%) is (passive force of the pump/motor axial power)×100, and the passive force of the pump (㎾) is density (kg/㎥) x gravity acceleration (9.8m/sec²) x flow rate (㎥/sec) It is calculated by x head (m).

The axial power of the motor (kW) can be calculated by the motor power input value (kW) x motor efficiency, but the motor efficiency is calculated by using the value provided by the manufacturer or by using a value commonly used in industry. do.

In actual pump operation, the motor efficiency may vary depending on the manufacturing process of the motor, deterioration of the motor over the course of the pump's usage time, and results of maintenance or maintenance of the motor, so assuming the efficiency of the motor and calculating the axial power of the motor, many errors Since it includes, there is a problem that can not accurately calculate the axial power of the motor.

To solve this, the axial power of the actual motor according to the pump operation can be calculated, and the axial power of the actual motor is calculated by the measured motor torque (kN·m) x the measured motor rotational speed (rad/sec). In order to calculate the axial power of the actual motor, a torque sensor is mounted between the motor rotational axis and the pump rotational axis, and a rotational speed measurement sensor is mounted on the motor rotational axis or pump rotational axis to directly measure the output torque and rotational speed of the pump motor, It can be calculated accurately by multiplying the motor's output torque and rotation speed.

In the Republic of Korea Patent Publication No. 10-2009-0081832 "electric pump performance test device" (published date: July 29, 2009) to control the motor of the electric pump using the monitor unit to drive the electric pump, and then the fluid sensor, motor Using the sensor, a torque sensor for detecting the rotational torque of the rotor in the pump, and an LP sensor that detects the rotational rate of the rotor, the amount of fluid transport, pressure, temperature, torque, rotation of the rotor of the pump Disclosed is an electric pump performance test apparatus that detects a number and receives it as a signal of an operation state of an electric pump through a signal processor.

In the prior art, in order to directly calculate the torque of the motor and calculate the axial power of the actual motor, a torque sensor must be installed between the motor rotational shaft and the pump rotational shaft, but such a torque sensor is expensive and between the motor mounted on the bed and the pump. It is necessary to change the design of the pump in order to secure space so that the torque sensor can be mounted, and the installation work must be performed so that the centers of the motor rotation axis, the torque sensor rotation axis, and the pump rotation axis coincide.

Also, in order to maintain the accuracy of the torque sensor, it needs to be periodically calibrated. Since each operation requires the separation, reinstallation and centering of the torque sensor, the pump needs to be costly and labor intensive. It is practically impossible to install a torque sensor on a field pump to test its performance.

Republic of Korea Patent Publication No. 10-2009-0081832 "electric pump performance test device" (published date: 2009.07.29)

The object of the present invention is to mount the rotational speed sensor to the motor output shaft of the motor detected using the instantaneous voltage measurement value supplied to the pump motor, the instantaneous current measurement value, the resistance value of the motor winding, and the motor rotational shaft or pump rotational axis. The purpose of the present invention is to provide a pump efficiency calculation method that can improve the accuracy of calculation of the shaft power and pump efficiency of a motor without changing the design of the motor shaft and the pump shaft by calculating the shaft power of the motor using the measured measured rotational speed.

In order to achieve the above object, the pump efficiency calculation method of the present invention is a method for calculating the pump efficiency of a pump started by a motor, wherein the average resistance of the motor winding when the pump is stopped and the suction port height and the suction port of the pump Before the start of the pump measuring the diameter, the discharge port height and the diameter of the discharge port of the pump; The discharge flow rate at which the fluid is discharged to the rear end of the pump during the operation of the pump, the shear fluid pressure and the shear fluid temperature at the front end of the pump, the rear end fluid pressure and the rear end fluid temperature at the rear end of the pump, and supplied to the motor A measurement step during the pump operation to measure the instantaneous voltage, the instantaneous current, and the motor rotation speed of the motor; A fluid density calculation step of calculating a shear fluid density at the front end of the pump based on the shear fluid pressure and the shear fluid temperature, and calculating a rear fluid density at the rear end of the pump based on the rear fluid pressure and the rear fluid temperature; An inflow flow rate calculating step of calculating an inflow flow rate into the pump by the discharge flow rate, the shear fluid density, and the downstream fluid density; A fluid velocity calculating step of calculating the inlet fluid velocity of the pump inlet and the outlet fluid velocity of the pump outlet by the inlet flow rate, discharge flow rate, inlet diameter, and outlet diameter; Calculating the pump lift of the pump by the shear fluid density, the rear fluid density, the shear fluid pressure, the downstream fluid pressure, the inlet height, the outlet height, the inlet fluid velocity, the outlet fluid velocity and the gravitational acceleration Pump head calculation step; A pump manual power calculating step of calculating the pump manual force of the pump by the rear stage fluid density, discharge flow rate, pump lift and gravity acceleration; A motor output torque calculating step of calculating the motor output torque by the average resistance of the motor winding, and the instantaneous voltage and instantaneous current supplied to the motor; A motor shaft power calculating step of calculating the motor shaft power of the motor according to the motor output torque and the motor rotation speed; And it characterized in that it comprises a pump efficiency calculating step of calculating the pump efficiency of the pump by the pump manual force and the motor shaft power.

In the pump efficiency calculation method of the present invention, the output torque of the motor is detected without changing the design of the pump, and the output torque of the motor detected by applying the method can be used to increase the accuracy of the pump efficiency calculation. In the process of manufacturing, pump installation, pump commissioning, and pump maintenance, the efficiency of the pump as well as the state of the motor can be accurately determined, so that the user can accurately determine the maintenance timing of the motor and pump.

1 is a flow chart showing a method for calculating the pump efficiency of the present invention,
2 is a configuration diagram of the pump showing the position of each sensor for explaining the pump efficiency calculation method of the present invention.

Hereinafter, a method for calculating the pump efficiency of the present invention will be described in detail with reference to the accompanying drawings.

1 and 2, the pump efficiency calculation method of the present invention, the average resistance (R) of the winding of the motor 20 when the pump 10 is stopped, and the inlet height h1 of the pump 10 ) And the inlet diameter (D1), the discharge port height (h2) and the outlet diameter (D2) of the pump (10) before the start of the pump measuring step (S10), and the operation of the pump (10) of the pump (10) The discharge flow rate (Q2) through which the fluid is discharged to the rear end, the shear fluid pressure (P1) and the shear fluid temperature (T1) at the front end of the pump 10, the rear end fluid pressure (P2) and the rear fluid temperature at the rear end of the pump (10) (T2), the instantaneous voltage (V1, V2, V3) supplied to the motor 20 and the instantaneous current (C1, C2, C3), and the pump operation to measure the motor rotation speed (w) of the motor 20 The shear fluid density (ρ1) of the front end of the pump (10) is calculated by the measurement step (S20), the shear fluid pressure (P1), and the shear fluid temperature (T1), and the downstream fluid pressure (P2) and the downstream fluid temperature (T2) ) By the fluid density calculation step (S30) for calculating the rear end fluid density (ρ2) at the rear end of the pump (10), the discharge flow rate (Q2), the shear fluid density (ρ1), and the rear end fluid density (ρ2). The inflow flow rate calculation step (S40) for calculating the inflow flow rate Q1 flowing into the pump 10, the inflow flow rate Q1, the discharge flow rate Q2, the inlet diameter D1, and the outlet diameter D2 The fluid velocity calculation step (S50) for calculating the inlet fluid velocity (Vin) of the pump 10 inlet and the outlet fluid velocity (Vout) of the pump (10) outlet, the shear fluid density (ρ1), and the downstream fluid density (ρ2), shear fluid pressure (P1), rear fluid pressure (P2), inlet height (h1), outlet height (h2), inlet fluid velocity (Vin), outlet fluid velocity (Vout), A pump head calculation step (S60) for calculating the pump head (H) of the pump 10 by gravity acceleration (g), the rear end fluid density (ρ2), the discharge flow rate (Q2), and the pump head (H) The pump manual force calculation step (S70) for calculating the pump manual force (Pwr_H) of the pump 10 by the gravitational acceleration (g), the average resistance (R) of the winding of the motor 20, and the motor (2) Motor output torque calculation step (S80) and motor output torque (Tq) for calculating motor output torque (Tq) by instantaneous voltage (V1, V2, V3) and instantaneous current (C1, C2, C3) supplied to 0) ) And motor rotation speed (w) to calculate the motor shaft power (Pwr_M) of the motor shaft 10 (S90) and the pump manual force (Pwr_H) and the motor shaft power (Pwr_M) pump 10 It consists of a pump efficiency calculation step (S100) for calculating the pump efficiency (η_P).

The operation of the method for calculating the pump efficiency according to the present invention is as follows.

As shown in Fig. 1, the measurement step (S10) before starting the pump is the average resistance (R) of the winding of the motor 20 when the pump 10 is stopped, the inlet height (h1) and the inlet diameter of the pump (10) (D1), the discharge port height (h2) and the discharge port diameter (D2) of the pump 10 are measured.

During the pump operation, the measurement step (S20) starts the motor 10 by applying an AC voltage of 3 phase to the motor 10, and when the pump 10 operates, fluid is discharged to the rear end of the pump 10. Discharge flow rate (Q2), shear fluid pressure (P1) and shear fluid temperature (T1) at the front end of the pump (10), rear end fluid pressure (P2) and rear end fluid temperature (T2) at the rear end of the pump (10), and motor The instantaneous voltages (V1, V2, V3), instantaneous currents (C1, C2, C3) supplied to (20), and the motor rotation speed (w) of the motor 20 are measured.

During the pump operation, the measurement step (S20), as shown in Figure 2, the pump 10 and the pipe side between the tank 30 in which the fluid is stored, that is, the front end of the pump 10, the pump 10 through the pipe Equipped with a pressure sensor and a temperature sensor for detecting the pressure and temperature of the fluid flowing into the front end, the shear fluid pressure (P1), which is the fluid pressure before the pump 10 by the pressure sensor and the temperature sensor during the operation of the pump 10 ) And the fluid temperature, shear fluid temperature (T1).

In the same manner as above, a pressure sensor and a temperature sensor are mounted on the rear end of the pump 20 to detect the rear end fluid pressure P2 and the rear end fluid temperature T2 at the rear end of the pump 20 during the operation of the pump 10.

In addition, by installing a flow sensor (Q) on the piping side of the rear end of the pump 20, the discharge flow rate (Q2) through which the fluid is discharged to the rear end side of the pump (10) during the operation of the pump (10) by the flow sensor (Q) ) Is detected, and an AC voltage of three phases is applied to the motor 10, so that the motor 10 is started, and the instantaneous voltages V1, V2, and V3, which are instantaneous values of the three phase AC voltages when the pump 10 is operated. Instantaneous currents C1, C2, and C3 are detected by respective instantaneous voltages V1, V2, and V3.

In addition, a rotational speed sensor is mounted on the rotational axis of the motor 20 or the rotational axis of the pump 10 to detect the motor rotational speed w of the motor 20 during the operation of the pump 10.

The fluid density calculation step (S30) calculates the shear fluid density (ρ1) of the front end of the pump 10 according to the thermodynamic state quantity table using the shear fluid pressure (P1) and the shear fluid temperature (T1), and the downstream fluid pressure (P2) ) And the rear end fluid temperature (T2) are used to calculate the rear end fluid density (ρ2) at the rear end of the pump (10).

Since the inflow flow rate (Q1) is the discharge flow rate (Q2) × (rear flow density (ρ2)/ shear flow density (ρ1)), the inflow flow calculation step (S40) is the discharge flow rate (Q2) and the shear flow density (ρ1) Wow, the influent flow rate Q1 flowing into the pump 10 is calculated by the rear end fluid density ρ2.

The outlet fluid velocity (Vout) is the discharge flow rate (Q2)/(π x the outlet diameter (D2)²/4), and the inlet fluid velocity (Vin) is the inlet flow rate (Q1)/(π x the inlet diameter (D1)²/ Since it is 4), the fluid speed calculating step S50 calculates the inlet fluid velocity Vin of the pump 10 inlet and the outlet fluid velocity Vout of the pump 10 outlet, respectively.

Since the pump head (H) is P2 / (ρ2 × g)-P1 / (ρ1 × g) + (h2-h1) + (Vin²+Vout²) / (2 × g), the pump head calculation step (S60) is the shear Fluid density (ρ1), rear end fluid density (ρ2), front end fluid pressure (P1), rear end fluid pressure (P2), inlet height (h1), outlet height (h2), and inlet fluid velocity (Vin) ), and the pump head (H) of the pump 10 is calculated by the discharge port fluid velocity (Vout) and the gravitational acceleration (g).

Since the pump manual force (Pwr_H) is ρ2 × g × Q2 × H, the pump manual force calculation step (S70) is applied to the rear end fluid density (ρ2), discharge flow rate (Q2), pump lift (H), and gravity acceleration (g). By this, the pump manual force Pwr_H of the pump 10 is calculated.

The motor output torque calculation step S80 is performed by the average resistance R of the windings of the motor 20, the instantaneous voltages V1, V2, and V3 supplied to the motor 20 and the instantaneous currents C1, C2, and C3. Calculate the motor output torque (Tq).

Since the motor shaft power Pwr_M is the motor output torque Tq×motor rotation speed w, the motor shaft power calculation step S90 calculates the motor shaft power Pwr_M.

Since the pump efficiency (η_P) is (pump manual force (Pwr_H)/motor shaft power (Pwr_M))×100, the pump efficiency calculation step (S100) calculates the pump efficiency (η_P).

The pump efficiency calculation method of the present invention by the above method does not change the design of the pump, detects the motor output torque (Tq) of the motor 20 in the motor output torque calculation step (S80), and detects the detected motor output torque. As the pump efficiency η_P is calculated in the pump efficiency calculation step S100 by (Tq), the accuracy of the pump efficiency calculation can be increased.

Based on the accurately calculated pump efficiency (η_P), it is possible to accurately determine the state of the motor as well as the efficiency of the pump in the process of pump manufacturing, pump installation, pump commissioning, and pump maintenance. The user can accurately judge.

Claims (1)

In the pump efficiency calculation method of the pump (10) started by the motor (20),
When the pump 10 is stopped, the average resistance R of the windings of the motor 20, the inlet height h1 and the inlet diameter D1 of the pump 10, and the outlet height of the pump 10 (h2) and the measuring step (S10) before starting the pump to measure the outlet diameter (D2);
A discharge flow rate (Q2) through which fluid is discharged to the rear end side of the pump (10) during the operation of the pump (10), a shear fluid pressure (P1) and a shear fluid temperature (T1) at the front end of the pump (10), The rear end fluid pressure (P2) and the rear end fluid temperature (T2) at the rear end of the pump (10), the instantaneous voltage (V1, V2, V3) and the instantaneous current (C1, C2, C3) supplied to the motor (20) , During the pump operation to measure the motor rotational speed (w) of the motor 20 (S20);
The shear fluid density (ρ1) of the front end of the pump (10) is calculated based on the shear fluid pressure (P1) and the shear fluid temperature (T1). A fluid density calculating step (S30) for calculating the rear end fluid density (ρ2) at the rear end of the pump 10;
An inflow flow rate calculating step (S40) for calculating the inflow flow rate Q1 flowing into the pump 10 by the discharge flow rate Q2, the shear fluid density r2, and the downstream fluid density r2;
The inlet flow rate (V1) of the inlet of the pump (10) and the outlet of the pump (10) by the inlet flow rate (Q1), the discharge flow rate (Q2), the inlet diameter (D1), and the outlet diameter (D2) A fluid speed calculating step (S50) for calculating the discharge fluid velocity (Vout);
The shear fluid density (ρ1), the rear fluid density (ρ2), the shear fluid pressure (P1), the rear fluid pressure (P2), the inlet height (h1), the outlet height (h2), and the inlet fluid velocity A pump lift calculation step (S60) for calculating the pump lift (H) of the pump (10) by (Vin), the outlet fluid velocity (Vout) and the gravitational acceleration (g);
Pump manual power calculation step for calculating the pump manual force (Pwr_H) of the pump 10 by the rear stage fluid density (ρ2), discharge flow rate (Q2), pump lift (H) and gravity acceleration (g) S70);
The motor output torque Tq is determined by the average resistance R of the windings of the motor 20, the instantaneous voltages V1, V2, and V3 and the instantaneous currents C1, C2, and C3 supplied to the motor 20. Calculating motor output torque step (S80);
A motor shaft power calculating step (S90) of calculating the motor shaft power (Pwr_M) of the motor 10 by the motor output torque (Tq) and the motor rotation speed (w); And
And a pump efficiency calculating step (S100) for calculating the pump efficiency (η_P) of the pump 10 by the pump manual force (Pwr_H) and the motor shaft power (Pwr_M).

Images