CN202280642U - Device for expanding stable running area of centrifugal compressor and centrifugal compressor - Google Patents

Abstract

The utility model discloses a device for expanding a stable running area of a centrifugal compressor. The device comprises a plurality of dynamic pressure sensors with high frequency response, a dynamic strain indicator with high frequency response, a signal conditioning device, a signal processing DSP (digital signal processer) module and an airflow jetting device, wherein the dynamic pressure sensors and the dynamic strain indicator are used for acquiring dynamic signals generated during the running of the compressor, the signal conditioning device is used for sending the dynamic signals to the DSP module, the DSP module is used for processing the dynamic signals and sending a demand to a controller for controlling the airflow jetting device to act. Through the adoption of the device disclosed by the utility model, the stable running area (stable work range) of the centrifugal compressor can be expanded, the damage of flowing unstability, namely stall and surging, can be eliminated or reduced. The utility model further discloses a centrifugal compressor equipped with the device for expanding the stable running area of the centrifugal compressor.

Description

Device for Widening the Stable Operation Range of Centrifugal Compressor and Centrifugal Compressor

technical field

The utility model relates to an accessory of a centrifugal compressor, in particular to a device for widening the stable operation area of the centrifugal compressor. The utility model also relates to a centrifugal compressor provided with a device for widening the stable operation area of the centrifugal compressor.

Background technique

Centrifugal compressors, as a general-purpose machine for increasing gas pressure, have been widely used in many sectors of the national economy and occupy an important position, especially in the metallurgical industry (blast furnace blast, oxygen steelmaking, oxygen production, etc.) , petrochemical (oil field gas injection, synthetic ammonia, urea, ethylene, petroleum refining, etc.), natural gas transmission, refrigeration, aviation and power (aero engines, gas turbines, internal combustion engine supercharging, power wind sources, etc.) and other industrial sectors.

Surge and stall are unstable flow states that occur when the compressor unit operates at a small flow rate due to factors such as changes in working conditions. The existence of these unstable flow phenomena has caused great harm to the structure of the compressor unit. For example, the unit will vibrate violently during the surge process, which will cause great damage to the seal, bearing and impeller. The change of the load of the compressor in a short time is also unfavorable to the drive system. If this situation is not taken seriously, it will cause parking accidents in enterprises and factories, which will bring large economic losses, and will cause major accidents such as machine crashes and production paralysis.

At present, in the industry, avoidance and passive control methods are still used to deal with the surge of centrifugal compressors, such as setting surge protection lines and action lines to prevent the compressor from operating in the surge region. Or use the method of casing treatment and bleed or backflow, but on the one hand, this method cannot make full use of the potential of the compressor, and it is easy to reduce the efficiency of the compressor at the non-surge point; on the other hand, this method is mostly in the Measures such as deflation are taken at the outlet of the compressor. Since the action cannot be near the fundamental position that causes the instability, the speed of releasing the instability is relatively slow, and it will cause a huge waste of energy.

Utility model content

The technical problem to be solved by the utility model is to provide a device for widening the stable operation area of the centrifugal compressor, which can eliminate or reduce the harm of flow instability, namely stall and surge.

In order to solve the above-mentioned technical problems, the technical solution of the utility model to widen the stable operation area of the centrifugal compressor is as follows:

It includes a plurality of high-response dynamic pressure sensors, a high-response dynamic strain gauge, a signal conditioning device, a signal processing DSP module, and an air jet device; the plurality of dynamic pressure sensors are evenly distributed circumferentially in the leafless space; The dynamic strain gauge is fixedly arranged on the wheel cover near the impeller inlet to collect dynamic signals when the compressor is running; the input ends of the signal conditioning equipment are electrically connected to the high-frequency response dynamic pressure sensor and the dynamic strain gauge respectively; The output end of the conditioning device is connected to the input end of the DSP module, and the DSP module calculates the average value and variance of the data points in a given time period and performs FFT analysis; the output end of the DSP module is connected to the controller through a signal transmission line, and the controller is connected to the air flow Injection device; the airflow injection device includes two groups of nozzles, one group of nozzles is arranged at the inlet of the impeller, and the other group of nozzles is arranged at the inlet of the vaned diffuser, and the number of each group of nozzles is at least eight; the outlet of the nozzles The section is flush with the impeller cover; the gas flow direction injected by the nozzle is opposite to the rotation direction of the compressor impeller.

When no external air source is available, the throat of the impeller is provided with a first group of air induction pipes, and the first group of air induction pipes is arranged at the circumferential middle position of the throat of the impeller; the throat of the vaned diffuser is provided with a second Two sets of bleed pipes, the second set of bleed pipes are arranged in the middle of the throat of the bladed diffuser, and the number of each set of bleed pipes is the same as the number of nozzles at the corresponding positions.

The first group of nozzles is connected to the first group of air-inducing pipes, and a gas injection control valve is arranged between the first group of nozzles and the first group of air-inducing pipes; the second group of nozzles is connected to the second group of air-inducing pipes A gas injection control valve is arranged between the second group of nozzles and the second group of air induction pipes; the gas injection control valves are respectively controlled by servo motors.

When an external gas source is available, each of the nozzles is connected to a gas injection control valve; a plurality of gas injection control valves are arranged on an annular gas buffer pipeline, and the inlet of the annular gas buffer pipeline is connected to the external air through a gas delivery valve. The nozzle is supplied with air from an external air source; the gas injection control valve is controlled by a servo motor.

The inner channel of the nozzle is axial, and the outlet channel of the nozzle transitions from the axial direction to the radial direction, so that the outlet section of the nozzle is flush with the impeller wheel cover; the diameter of the inner channel is larger than the diameter of the outlet channel, forming a gradual Constricted runner.

The outlet cross-sectional size of the nozzle is determined according to the outlet flow rate of the nozzle.

The utility model also provides a centrifugal compressor equipped with a device for widening the stable operation area of the centrifugal compressor, and its technical solution is:

Including impeller, radial channel type vane diffuser, axial channel, the impeller, vane diffuser, axial channel form an air flow channel; multiple dynamic pressure sensors are evenly distributed circumferentially on the disc side in the vaneless space; dynamic The strain gauge is fixed on the wheel cover near the impeller inlet; multiple dynamic pressure sensors and dynamic strain gauges are respectively electrically connected to the input end of the signal conditioning equipment, the output end of the signal conditioning equipment is connected to the input end of the DSP module, and the DSP module’s The output end is connected to the controller through a signal transmission line, and the controller is connected to the airflow injection device; the airflow injection device includes two groups of nozzles, the first group of nozzles is arranged at the inlet of the impeller, and the second group of nozzles is arranged at the inlet of the vaned diffuser, each The number of nozzles in the group is at least eight; the outlet section of the nozzles is flush with the wheel cover of the impeller; the flow direction of the gas injected by the nozzles is opposite to the rotation direction of the impeller of the compressor.

The inner channel of the nozzle is axial, and the outlet channel of the nozzle transitions from the axial direction to the radial direction, so that the outlet section of the nozzle is flush with the impeller wheel cover; the diameter of the inner channel is larger than the diameter of the outlet channel, forming a gradual Constricted runner.

When no external air source is available, the throat of the impeller is provided with a first group of air induction pipes, and the first group of air induction pipes is arranged at the circumferential middle position of the throat of the impeller; the throat of the vaned diffuser is provided with a second Two sets of bleed pipes, the second set of bleed pipes are arranged at the circumferential middle position of the vaned diffuser throat, the number of each set of bleed pipes is the same as the number of nozzles at the corresponding position; when an external air source is available, each Each nozzle is respectively connected to a gas injection control valve; multiple gas injection control valves are arranged on an annular gas buffer pipeline, and the inlet of the annular gas buffer pipeline is connected to an external gas source through a gas delivery valve, and the nozzles are supplied by the external gas source. gas; the gas injection control valve is controlled by a servo motor.

The technical effect that the utility model can reach is:

The utility model achieves the purpose of expanding the stable working range of the centrifugal compressor by regulating the flow of the impeller inlet, the impeller throat, the inlet of the vane diffuser and the throat of the vane diffuser of the centrifugal compressor.

The utility model arranges a controllable airflow injection device at the inlet of the centrifugal impeller and the space without blades, and improves the flow conditions of the inlet of the centrifugal impeller and the inlet area of the diffuser with blades by injecting high-pressure airflow, thereby widening the stable working area of the system, and Eliminate the factors that caused the instability.

The utility model avoids the surge phenomenon of the centrifugal compressor by means of active control, and at the same time takes into account all possible conditions that cause the surge of the centrifugal compressor, and does not change the steady state of the system in other stable working areas except the surge characteristics, while broadening the stable operating range of the compressor and improving the aerodynamic performance of the compressor, it can eliminate the disadvantages of efficiency and pressure ratio loss under normal working conditions using passive control methods.

The utility model can widen the stable operation area of the centrifugal compressor, that is, the stable working range, so that the existing centrifugal compressor can work near the high-pressure ratio and high-efficiency area as much as possible, thereby realizing the purpose of energy saving.

The utility model is based on the internal flow of the centrifugal compressor, analyzes the cause of the instability from the perspective of the physical mechanism, and can obtain a greater effect at a lower cost.

Description of drawings

Below in conjunction with accompanying drawing and specific embodiment, the utility model is described in further detail:

Fig. 1 is the schematic diagram of the device for widening the stable operation region of the centrifugal compressor of the utility model;

Fig. 2 is a side sectional view of Fig. 1;

Fig. 3 is the schematic diagram of the nozzle of the present utility model;

Fig. 4 is a work flow diagram of the utility model.

Explanation of the reference signs in the figure:

1 is the impeller inlet, 2 is the impeller outlet,

3 is the inlet of the vane diffuser, 4 is the outlet of the vane diffuser,

5 is the outlet of the axial channel, 8A is the dynamic pressure sensor,

8B is the dynamic strain gauge, 9A is the second group of nozzles,

9B is the first group of nozzles, 10B is the first group of air induction pipes,

10A is the second group of air induction pipes, and 7 is a vaned diffuser.

Detailed ways

The utility model widens the stable operation area of the centrifugal compressor device, which includes a plurality of high-response dynamic pressure sensors, a high-response dynamic strain gauge, a signal conditioning device, a signal processing DSP module and an air jet device;

A plurality of dynamic pressure sensors are evenly distributed circumferentially in the vane-free space between the impeller outlet and the vane diffuser;

For a centrifugal compressor with a vane diffuser, the vaneless space plays a key role in instability, and the flow in the vaneless space directly determines the flow condition of the compressor. The utility model arranges a plurality of dynamic pressure sensors in this In the leafless space, the flow condition of the compressor can be monitored, and the early warning of surge can be realized in advance from the spatial Fourier analysis of the signal and the variance variation of the signal;

The dynamic strain gauge is fixed on the wheel cover near the impeller inlet; the dynamic strain gauge is used to collect the dynamic signal when the compressor is running, and can simultaneously measure the tangential and axial speed signals;

If the compressor runs near the surge point (that is, the instability point), there will be backflow at the impeller inlet near the wheel cover. At this time, the flow field distribution at this place, that is, the tangential and axial velocities, will be changed, thereby changing The force of the fluid on the strain gauge. The utility model is equipped with a dynamic strain gauge at this position. The dynamic strain gauge is used to monitor the change of the tangential and axial force applied to the strain gauge by the fluid during the process of approaching the instability. From this value Realize the early warning of surge in the sudden change;

The input terminals of the signal conditioning equipment are electrically connected to the high-response dynamic pressure sensor and the dynamic strain gauge; the signal conditioning equipment has multi-channel input and output terminals, which are used to amplify, filter and A/D analog-to-digital conversion of the signal; The output end of the conditioning device is connected to the input end of the DSP module;

The output of the DSP (Digital Signal Processing, digital signal processing) module is connected to the controller through the signal transmission line, and the controller is connected to the air jet device; the DSP module calculates the average value and variance of the data points in a given period of time and performs FFT (fast Fourier transform) )analyze;

The DSP module is used to find abnormal characteristics from the conditioned signal to make a judgment on the current operating state of the compressor, and send an actuation signal to the actuation mechanism of the air jet device through the controller, so as to realize the regulation of the flow;

The air jet device includes two sets of nozzles, the first set of nozzles is set at the inlet of the impeller, the second set of nozzles is set at the entrance of the vaned diffuser, the number of each set of nozzles is at least eight, and the outlet section of the nozzles is on the same level as the impeller cover. The direction of the gas injected by the nozzle is opposite to the direction of rotation of the impeller of the compressor;

In the case of an external gas source, each nozzle is connected to a gas injection control valve; multiple gas injection control valves are arranged on an annular gas buffer pipeline, and the inlet of the annular gas buffer pipeline is connected to an external gas source through a gas delivery valve , the nozzle is supplied with air from an external air source; the gas injection control valve is controlled by a servo motor;

In the case of no external air source, the throat of the impeller is provided with a first group of air induction pipes, and the throat of the diffuser with vanes is provided with a second group of air induction pipes; the first group of nozzles is connected to the first group of air induction pipes, and the second A gas injection control valve is set between one group of nozzles and the first group of bleed pipes, and the gas injection control valve is controlled by a servo motor; the second group of nozzles is connected to the second group of bleed pipes, and the second group of nozzles is connected to the second A gas injection control valve is set between the bleed air pipes, and the gas injection control valve is controlled by a servo motor; the two sets of nozzles are controlled by the high-pressure gas inside the compressor flow channel and located downstream of the nozzles (that is, the throat of the impeller and the throat of the diffuser). Realize air supply.

The controller is connected to the servo motor of the air jet device through a signal transmission line;

The air injection device is used to inject a certain amount of high-pressure gas into the flow channel of the centrifugal compressor, thereby changing the flow field structure at the impeller inlet or diffuser inlet, and achieving the critical flow corresponding to delaying surge;

According to the outlet flow velocity of the nozzle, determine the outlet section size of the nozzle; make the outlet flow velocity of the nozzle reach the local sound speed, so that it can be blocked under the condition of small flow rate, so as to change the gas pressure at the nozzle outlet;

The utility model sprays gas against the direction of airflow rotation inside the flow channel of the centrifugal compressor, which can reduce the blade attack angle at the impeller inlet and improve the flow in the blade top area; reduce the airflow angle of the gas entering the bladed diffuser and the diffuser. The angle of attack of the compressor blades can reduce the diffusion ratio from the impeller outlet to the diffuser inlet, and eliminate the stall mode of circumferential rotation in the bladeless space, thereby improving the flow state of the diffuser throat;

As shown in Figure 4, the high-frequency response dynamic pressure sensor and dynamic strain gauge collect signals in real time from the impeller inlet and the bladeless space, and transmit the signals to the signal conditioning equipment; Data conversion, and the signal is sent to the DSP module; the DSP module processes the signal, and compares the signal with the preset surge alarm value, if it does not meet the preset requirements, it will not send a control signal and continue Dynamic signal acquisition; if the preset requirements are met, a control signal is sent to the controller according to the set threshold; The alarm situation determines the control area, and determines the action sequence and valve opening of the gas injection control valve in the area to be controlled, so as to realize the expansion and stability.

As shown in Fig. 1 and Fig. 2, the utility model is provided with a schematic diagram of a centrifugal compressor with a device for widening the stable operation area of the centrifugal compressor, including an impeller, a radial channel type vane diffuser, and an axial channel, and the gas flows from the impeller The inlet 1 flows in, passes through the work of the impeller, passes through the outlet 2 of the impeller, enters the inlet 3 of the vane diffuser 7, passes through the diffusion of the vane diffuser, and enters the axial passage through the outlet 4 of the vane diffuser, and finally Access to subsequent components via the outlet 5 of the axial channel;

A plurality of dynamic pressure sensors 8A are evenly distributed circumferentially on the wheel disk side in the vaneless space between the impeller outlet 2 and the vaned diffuser;

The dynamic strain gauge 8B is fixed on the wheel cover near the impeller inlet 1;

Due to the influence of Coriolis force and channel curvature, the low-energy fluid (wake) at the outlet of the impeller generally gathers at the side of the wheel cover near the suction surface. The utility model selects the position of the dynamic strain gauge 8B for measuring the gas injection at The wheel cover side, while the dynamic pressure sensor 8A is arranged on the wheel disc side, the number of sensors is at least 8, so that the fourth order harmonic of the space can be captured.

The first group of nozzles 9B is arranged at the inlet 1 of the impeller, and the second group of nozzles 9A is arranged at the inlet 3 of the bladed diffuser 7;

The impeller throat refers to the minimum distance O1 between two adjacent impellers. The impeller throat is provided with a first group of air-inducing pipes 10B, and the first group of air-introducing pipes 10B is arranged at the circumferential middle position of the impeller throat;

The throat of the vaned diffuser refers to the minimum distance O2 between two adjacent blades of the diffuser. The throat of the vaned diffuser is provided with a second group of air induction pipes 10A, and the second group of air induction pipes 10A is arranged on The circumferential middle position of the throat of the vaned diffuser;

The number of the first group of air-introducing pipes 10B is the same as the number of the first group of nozzles 9A, and the number of the second group of air-introducing pipes 10A is the same as that of the second group of nozzles 9B, that is, the air-introducing pipes correspond to the nozzles in corresponding positions one by one.

As shown in Figure 3, the inner flow path of the nozzle is axial, and the outlet flow path of the nozzle transitions to the radial direction, so that the outlet section of the nozzle is flush with the impeller cover; the diameter of the inner flow path is larger than the diameter of the outlet flow path, Form a tapered flow channel;

The utility model makes the outlet section of the nozzle flush with the impeller cover, can make full use of the gas Coanda effect (that is, the Coanda effect), not only improves the flow of the low-speed fluid in the boundary layer, but also does not cause the gas injection valve to be damaged due to the existence of the nozzle. The action affects the flow field inside the compressor, thereby changing the performance of the compressor in a stable working state.

When the number of stages of the centrifugal compressor changes, it is enough to increase or decrease the number of sensors, the number and position of nozzles accordingly.

The utility model can be used for gas turbines and compressors in industrial processes.

Claims (9)

1. a device of widening the centrifugal compressor stable operation zone is characterized in that: comprise the dynamic pressure transducer of a plurality of high frequency sound, dynamic strainometer, a signal condition equipment, a signal processing DSP module and the air flow jetting device of a high frequency sound;

Said a plurality of dynamic pressure transducer circumferentially is distributed in the no vane space;

Near the wheel that said dynamic strainometer is fixedly set in the impeller inlet covers, the Dynamic Signal when gathering compressor operating;

The input end of said signal condition equipment electrically connects with high frequency sound dynamic pressure transducer, dynamic strainometer respectively; The output terminal of signal condition equipment connects the input end of said DSP module, mean value, the variance of data point and carry out fft analysis in the DSP module calculated for given time period;

The output terminal of DSP module connects controller through signal transmssion line, and controller connects the air flow jetting device;

Said air flow jetting device comprises two groups of nozzles, and first group of nozzle is arranged at impeller inlet, and second group of nozzle is arranged at the import of vaned diffuser, and the number of every group of nozzle is at least eight; The outlet of said nozzle is concordant with enclosing cover for impeller; The gas flow that nozzle sprayed is opposite with the sense of rotation of compressor impeller.

2. the device of widening the centrifugal compressor stable operation zone according to claim 1 is characterized in that: but in the no external air source time spent, said impeller throat is provided with first group of air entraining pipe, and first group of air entraining pipe is arranged at the circumferential neutral position of impeller throat; The throat of said vaned diffuser is provided with second group of air entraining pipe, and second group of air entraining pipe is arranged at the circumferential neutral position of vaned diffuser throat, and the number of every group of air entraining pipe is identical with the number of nozzle of corresponding position.

3. the device of widening the centrifugal compressor stable operation zone according to claim 2 is characterized in that: said first group of nozzle and first group of air entraining pipe interconnect, and are provided with the gas blowing control valve between said first group of nozzle and first group of air entraining pipe; Said second group of nozzle and second group of air entraining pipe interconnect, and are provided with the gas blowing control valve between said second group of nozzle and second group of air entraining pipe; Said gas blowing control valve is controlled through actuating motor respectively.

4. the device of widening the centrifugal compressor stable operation zone according to claim 1 is characterized in that: but the external air source time spent is being arranged, and said each nozzle connects a gas blowing control valve respectively; A plurality of gas blowing control valves all are arranged on the annular gas buffering pipe, and the inlet of annular gas buffering pipe connects external air source through gas delivery valve, and said nozzle is realized air feed by external air source; Said gas blowing control valve is controlled through actuating motor.

5. according to claim 1 or the 2 or 3 described devices of widening the centrifugal compressor stable operation zone; It is characterized in that: the inner flow passage of said nozzle is for axial; The outlet flow of nozzle to radially, makes the outlet of nozzle concordant with enclosing cover for impeller by axial transitions; The diameter of inner flow passage forms the tapered runner greater than the diameter of outlet flow.

6. the device of widening the centrifugal compressor stable operation zone according to claim 5 is characterized in that: the outlet size of said nozzle is decided according to the exit velocity of nozzle.

7. one kind is provided with the described centrifugal compressor of widening the device of centrifugal compressor stable operation zone of claim 1; It is characterized in that: comprise impeller, radial passage type vaned diffuser, axial passage, impeller, vaned diffuser, axial passage form air-flow path;

A plurality of dynamic pressure transducers circumferentially are distributed on the wheel disc side in the no vane space;

Near the wheel that dynamic strainometer is fixedly set in the impeller inlet covers;

A plurality of dynamic pressure transducers, dynamic strainometer electrically connect with the input end of signal condition equipment respectively; The output terminal of signal condition equipment connects the input end of DSP module; The output terminal of DSP module connects controller through signal transmssion line, and controller connects the air flow jetting device;

Said air flow jetting device comprises two groups of nozzles, and one group of nozzle is arranged at impeller inlet, and another group nozzle is arranged at the import of vaned diffuser, and the number of every group of nozzle is at least eight; The outlet of said nozzle is concordant with enclosing cover for impeller; The gas flow that nozzle sprayed is opposite with the sense of rotation of compressor impeller.

8. the centrifugal compressor that is provided with the device of widening the centrifugal compressor stable operation zone according to claim 7; It is characterized in that: the inner flow passage of said nozzle is for axial; The outlet flow of nozzle to radially, makes the outlet of nozzle concordant with enclosing cover for impeller by axial transitions; The diameter of inner flow passage forms the tapered runner greater than the diameter of outlet flow.

9. the centrifugal compressor that is provided with the device of widening the centrifugal compressor stable operation zone according to claim 7; It is characterized in that: but in the no external air source time spent; Said impeller throat is provided with first group of air entraining pipe, and first group of air entraining pipe is arranged at the circumferential neutral position of impeller throat; The throat of said vaned diffuser is provided with second group of air entraining pipe, and second group of air entraining pipe is arranged at the circumferential neutral position of vaned diffuser throat, and the number of every group of air entraining pipe is identical with the number of nozzle of corresponding position; But the external air source time spent is being arranged, and said each nozzle connects a gas blowing control valve respectively; A plurality of gas blowing control valves all are arranged on the annular gas buffering pipe, and the inlet of annular gas buffering pipe connects external air source through gas delivery valve, and said nozzle is realized air feed by external air source; Said gas blowing control valve is controlled through actuating motor.

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