SU1377461A1 - Method and apparatus for protecting compressor against stalling and surging - Google Patents

Abstract

The invention makes it possible to increase the reliability of protection of a compressor equipped with a drive with speed control. The device contains a sensor 2-4 tons of air at the inlet and outlet of the compressor, pressure difference at the inlet measuring diaphragm, sensors 5.7, comparison unit 6, sensors 8.9 of the air pressure at the entrance and exit of the compressor, blocks 10,16 division, bypass valve actuator 11, adders 12,19, multiplication blocks 13,17,18, polarized relay 14, time relay 15, compressor drive 20, rotational speed controller 21 with sensor 22, unit 23, unit 24 adjustment, comparison unit 25 and setpoint correction unit 26. According to the measured pressure signals and air temperature at the inlet and outlet of the compressor and the pressure drop, the value of the control signal is formed at the input measuring diaphragm. When the latter exceeds a given value, the jumpers change the setpoint of the speed regulator within the specified limits and give a signal to the valve actuator for a predetermined period of time up to 10 minutes. After holding the specified time interval, relay 15 sends a command to actuator 11 to close the bypass valve. T.V. as a result of an increase in the rotational speed and the bypass, the normal operation of the compressor is restored. 2 sec. f-ly, 1 ill. 1 s (L CO 4: O5

Description

The invention relates to the protection of compresses against surge.

The purpose of the invention is to increase the reliability of the protection of the compressor, equipped with a drive with speed control.

The drawing shows the block diagram of the device that implements this method

The device for protection of compressor 1 against surge contains sensor 2 for air temperature at the compressor inlet, sensor 3 for air temperature at the code of the compressor, sensor 4 for differential pressure at the input measuring diaphragm, the first unit 5 connected to unit 6 of the comparison, the second unit 7, sensor 8 air pressure at the compressor inlet, air pressure sensor 9 at the compressor inlet, first dividing unit 10, bypass valve actuator 11, first adder 12, first multiplying unit 13, polarized relay 14, time relay 15, sequentially connected to the second dividing unit 16, the second multiplying unit 17, the third multiplying unit 18 and the second adder 19. In addition, the drawing shows the compressor drive 20 and the rotational speed controller 21 with the rotational speed sensor 22 by the setting unit 23, the control unit 24, the unit 25 comparison and setpoint correction block 26.

The method is implemented in the device as follows.

The signals from sensors 2 and 8 of temperature and air pressure at the inlet to the compressor go to the second and first blocks of division 16 and 10, respectively, to the second inputs of which, respectively, signals from sensors 3 and 9 of temperature and air pressure at the outlet from the compressor are received. At the output of the first division block 10, a signal is generated that is proportional to

R . where R. - gas pressure at the entrance

one,

in the compressor, Pj is the gas pressure on

output from the compressor} K, is a constant. At the output of the second dividing unit 16, a signal is formed that is proportional to T-g

Ny Kf-, where T, is the gas temperature

at the entrance to the compressor; T is the gas temperature at the outlet of the compressor; K, is a constant. The signals from the outputs of the first and second division blocks go to the second multiplier 17 and then to the input of the third multiplier 18. The third input of the third multiplier 18 receives a signal from the output of the first multiplier 13, proportional to K dR, where rp is the pressure drop at the input Compressor J K, is a constant defined by the second admitter 7.

At the output of the third multiplier 18, a signal is generated that is proportional to K

P, - T

Rt

Gd 1,

Mr. LR, where K is a constant. From the output of the third multiplying unit, the signal is fed to the input of the second adder 19, to the other input of which the output signal of the first

adder 12, proportional to P,. The output of the second adder generates a signal proportional to PiT

P, -R, -K

P, T,

rr that is served on

block 6 is compared with the set value S, the value of which is formed by the first setter 5. If the output signal of the second adder is less than the set value, then the polarized relay 14 is activated and the signal corresponding to a logical unit is sent to the time relay 15 and block 26 inputs. If the output of the second adder is greater than the specified value, then the inputs of time relay 15 and block 26 receive a zero signal. When a single signal arrives at time relay 15, which corresponds to the approach of the compressor operation mode to the surging boundary, the latter executes a control command to open the bypass valve by the actuator 11 for a predetermined time interval (up to 10 min). When a single signal is received at the setpoint correction correction block 26, the rotational speed controller 21 increases the rotational speed of the compressor drive by a constant value to 2% of the nominal value. When removing a single signal, the rotational speed remains at the same level. An increase in the rotation frequency is carried out in steps of a nominal value. After holding the specified time interval up to 10 minutes, time relay 15 issues a command to actuator 11 to close the bypass valve. Thus, as a result of an increase in the rotational speed and the bypass, the normal operation of the compressor is restored.

Claims (2)

1. A method of protecting a compressor from surge by measuring the pressure and temperature of the air at the inlet and outlet of the compressor, as well as the differential pressure of the air at the input measuring diaphragm, forming a control signal from the measured values, and when the control signal exceeds the specified value of the signal applied to the drive a bypass valve, characterized in that, in order to increase the reliability of the protection of the compressor, equipped with an actuator with speed control, in addition, when the control signal exceeds a predetermined the magnitudes change abruptly within the prescribed limits of the setting of the rotational speed regulator, and the signal to the drive of the bypass valve is supplied for a specified period of time. 2. A compressor surge protection device containing air inlet and outlet temperature sensors of the compressor, a differential pressure sensor at the inlet measuring diaphragm, the first setpoint device connected to the comparison unit, the second setpoint device, pressure sensors inlet and outlet of the compressor, connected to the first dividing unit, as well as a bypass valve actuator, characterized in that, in order to increase the reliability of protection of the compressor, equipped with a drive with speed control, it additionally contains the first totalizer, the first. the multiplication block, the polarized relay, the time relay and the second division block connected in series, the second multiplication block, the third multiplication block and the second adder connected by the second input to the first adder, and the output to the block with equal, the first multiplication unit is connected by inputs to the differential pressure sensor and to the second setting unit, by the output to the third multiplying unit, the first adder is connected by inputs to the air pressure sensors at the inlet and outlet of the compressor, the second division unit is connected by inputs to the air temperature sensors at the input and output of the compressor, the polarized relay is connected to the comparison unit, and the output to the rotational speed controller, the first dividing unit is connected to the second input of the second multiplication unit, and a time relay but the input to the polarized relay, and the outputs to the actuator of the bypass valve.