DE2116758A1 - Method and device for preventing the pumping of speed-controlled axial compressors - Google Patents

Description

Method and device for preventing the pumping of speed-controlled Axial compressors The invention relates to a method and a device for prevention the pumping of speed-controlled axial compressors, which are based on pressure or volume-controlled Gaanetze work and their prime movers, e.g. B. Turbines, with a speed controller and equipped with a setpoint adjustment device; are.

The surge limit in the axial compressor map can be t, taking into account the respective prevailing atmospheric conditions (pressure Pl upstream of the axial compressor and temperature upstream of the axial compressor) using the following equation: p2 ' = f (m, p1, T1).

Since the mass throughput per unit of time is proportional to a good approximation is the speed, the following equation can also be set up; p2, = k1. f (n, P T1).

Here are: n = speed of the axial compressor P1 - pressure before Axial compressor T1 = absolute temperature m = mass flow rate of the axial compressor per unit of time k1 = & Anti-surge devices are known which are used in Approach of the axial compressor from the stable working area to the surge limit or when the surge limit is exceeded, i.e. when leaving the stable working area of the axial compressor - which is the case if the pressure behind the compressor p2> p2 ', i.e. H. so when pumping phenomena occur - a valve behind open the compressor, the speed n of the axial compressor being kept constant will. This increases the delivery rate of the compressor while the speed is kept constant and the pressure downstream of the compressor drops until p21 is p2.

This device can only be used with individually operated axial compressors or if between the feeds of the individual axial compressors on a gas network the pipeline resistances of the gas network are sufficiently high. With pressure or volume controlled Gas networks in which only one or some of the compressors are used for pressure or volume control are used and where the last-mentioned condition is not or not always is fulfilled, the storage volume of which is also large and / or in which the performance of the axial compressor to be protected against pumping compared to the total output of the feeding compressor is small, the described method to prevent pumping fails, because the blown air does not only come from the pumping axial compressor and because through adjustments in the pressure or quantity control circuit, which is carried out by another compressor can be closed, the amount blown off is always replenished and thereby there is no pressure drop after the axial compressor.

Another well-known method is to have them all on one network working axial compressor in the pressure resp.

Include volume control and the axial compressors in their entirety to run in such a way that pumping of the axial compressor does not occur. But that requires synchronously operating speed setpoint adjustment devices and approximately the same Kennefelder of the individual axial compressors. Furthermore, this procedure can be due to the high transfer factor (pressure or volume reduction: speed change) of the Pressure or volume control system or because of its change by switching off a Machine can easily lead to instabilities in the pressure or volume control loop.

-The purpose of the invention is to remedy the disadvantages mentioned of the beks nn th 1'up-prevention devices or processes for speed-controlled axial compressors, who work on pressure or volume-regulated gas networks and their propulsion machines, z. 3. Turbines, equipped with a speed controller and a setpoint adjustment device are to be avoided.

The invention is based on the object of creating a method through the egg gas networks, through axial compressors and, if necessary, through compressors of a different type and in which only one or some of the compressors can be used for pressure or volume control, a pumping of the axial compressor is prevented.

This object is achieved according to the invention in that in gas networks of the type mentioned and when using prime movers for the compressors that are equipped with a speed controller and a setpoint adjustment device, the speed of the axial compressor (s) approaching the surge limit to prevent the surge limit from being exceeded and that is due to the increase in speed more gas volume in blown off in a known manner or into the intake duct of the axial compressor or compressors that come close to the surge limit, optionally cooled, blown around.

To carry out this method it is according to a further feature the invention advantageous, the pressure p2 downstream of the compressor with one on the Surge limit lying, from the respective speed n or the respectively required Gas quantity m of an axial compressor formed, the function p2 '= f (m, p1, T1) = k1. f (n, p1, D1) to merge the following quantity p2 'and for the state p2> P2 to increase the speed of the axial compressor until such a rate is reached has that the state P2 = P2 has been reached.

In order to have the most stable possible behavior of the axial compressor in the immediate To get near the surge line, it is according to a further feature of the invention It is advantageous to use a comparative variable p2 "instead of the variable p2 'which is based on one at a safe distance from the surge limit in the stable area of the map of the axial compressor is the line that corresponds to the function lt P2 = P2 + k2 follows. k2 is a constant factor representing the safety margin.

In order to avoid instabilities in the gas network, it is advisable to use the Blow-off or blow-off valve manually or automatically only then streak after the surge limit controller of the axial compressor terminates the set speed increase and no surge limit controller of another machine has responded and the status p2 # p2? t reached in all axial compressors regulated with regard to the surge limit is.

Since the respective Tempcatur T1 in front of the compressor and the respective Pressure p1, also upstream of the compressor, influences the course of the surge limit, it is recommended the quantity p2 "with the change in temperature T1 and the pressure p1 to be corrected according to the function P2 '= £ t2' Pl, T1) + k2 = k1 f (n, P1, Tl) + k2.

The method according to the invention can be carried out by means of a device with the speed and pressure measuring elements via a non-linear element or act on a mixing point via a computing element, from which via diode, amplifier and threshold value switch by means of a setpoint adjustment device or transmitter device The speed of the drive machine and compressor are increased or decreased via intermediate links. the ADhlasav ntil is opened until the axial compressor returns to the stable Area of the compressor map.

To take into account the respective influencing the course of the surge line, Before em compressor prevailing temperature and the pressure of the gases are at a further execution of the device by means of temperature and pressure measuring elements via appropriately designed computing elements and a summing point Correction values are added to the signal from the compressor discharge pressure.

For further training of the facility to carry out the procedure is the threshold switch via OR and AND elements with a signaling device, which indicates the setting of the valve and the operating status of the pump limit controller, connected or the threshold switch is connected to the surge limit regulators of parallel machines in such a way that a closing to ensure stability in the gas network the blow-off or blow-off valve is only possible when the pressure behind the compressor in all axial compressors regulated with respect to the surge limit below the surge limit lies.

The method according to the invention and several devices for it Implementation are described below using some circuit diagrams, for example.

They show: FIG. 1 - a speed-pressure diagram which shows the course of the Surge limits at different pressures prevailing upstream of the axial compressor and Temperatures shows, Fig, 2 - the circuit diagram of a device for iVerhiten the Pumping of speed-controlled axial compressors in a simple design, Fig. 3 the circuit diagram of a device similar to that of FIG. 2, but with a different one Pressures and temperatures in front of the compressor taking into account correction arrangement, Fig. 4 - the circuit diagram of a further development of the device according to Fit. 3 that cesures that the closing of the relief or unloading valve only takes place after the surge limit controller of the axial compressor ends the setpoint speed increase and no Has raised the pump limit rule of another machine, Fig. 5 to 8 - several different partial circuit diagrams of the device according to the invention.

In Fi. 1 cie curves 1 and 2 represent the surge limit at 253 ° K and 785 or 735 Torr and curves 3 and 4 show the surge limits at 305 o K and 785 and 735 Torr, respectively.

Located below each curve; the corresponding compressor map, within which the axial compressor works in the stable area.

In the circuit diagram of FIG. 2, the axial compressor 5 is of a Prime mover, e.g. B. by a turbine 6, driven with a speed controller 7 together with the associated speed measuring element 8 and actuator 9 for the propellant inlet valve 10 is equipped. In the case of the invention Execution of the anti-surge device v4ird the speed n measured by the speed measuring element 11 and the experience dem non-linear element 12 supplied. This provides a signal at the output that the Pressure p2 "close to the surge limit of the axial compressor for a certain condition as a function of the speed n of the axial compressor, d. 1.

p2 "= k1. f (n) + k2, simulated. This signal becomes the mixing point 13 given.

The pressure prevailing behind the axial compressor 5 is Lit the pressure measuring element 14 measured and fed to the mixing point 13 via the computing element 15. The difference the two signals from the non-linear element 12 and from the arithmetic logic unit 15 controls the Amplifier 16. With the diode 17 it is achieved that the amplifier 16 with a downstream Threshold switch 18 only receives a signal from the mixing point 13 when its Output signal is positive.

In this case, the transmitter device 19 (adjustment potentiometer) and the motor-driven setpoint adjustment device 20 a signal, whereby they so adjusted ground that the speed of the turbine 6 and the Werdichters 5 so long increased and the hbblaseventil 21 via the amplifier 22 and the actuator 23 so is opened for a long time until the threshold switch 18 is tilted into the zero position. This is the case when the axial compressor 5 is restored by increasing the speed has reached the stable area of the compressor map, which causes the output signal the mixing point 13 approaches the value zero.

To the measured by the pressure measuring element 14 behind the compressor 5 Correct pressure P2 depending on the atmospheric conditions in the device according to FIG. 3, which is basically the in Xig. 2 shown corresponds to the measurement of the temperature and the pressure of the sucked in by the compressor 5 Gas, a temperature measuring element 26 and a pressure measuring element 27 are arranged.

Both measuring members 26 and 27 are via Reclienglieder 28 and 29, respectively one encoder each for programming according to a reference variable, in the present case the speed n, connected to a summing element 30, with which the the gas pressure behind the compressor 5 measuring pressure measuring element 14 via the computing element 15 is connected.

The signal of the corrected pressure p2 given by the summing element 30 is fed to the mixing point 13. The difference obtained in this table position 13 of the two signals from the summing element 30 and from the non-linear element 12 controls, each is described in the device according to FIG. 2, via diode 1?, amplifier 16, threshold value switch 18 and then the speed n resp.

Via transmitter device 19, amplifier 22, actuator 23 and relief valve 21 the blow-off quantity of the more gas quantity delivered by the increase in speed.

The scheme shown in Fig. 4 represents a further development of the Schemas according to Fig. 3. The output of the threshold switch 18 is via an OR gate 31 connected to the setpoint adjustment device 20 in such a way that it controls the setpoint speed higher. At the same time, by connecting the output of the threshold switch 18 with the negated input of an AND element 32 reaches that possibly pending Signals to reduce the speed become ineffective.

Furthermore, the output of the threshold switch 18 is via the OR element 33. With the transmitter device 19 in connection that there is an output signal of the threshold switch 18 causes the blow-off valve 21 to open.

The output of the threshold switch 18 is also negated Input of an AND gate 34 connected, »by causing the closing of the Äbblaseventils 21 is interrupted or prevented.

The output of the threshold switch 18 is connected to a negated input an AND gate 35 connected to the other input of the signal generator 36 the valve 21 coming, indicating the non-closed state of the valve 21, Signal led; is, whereby at the output of the AND gate 35 the message "valve open and pupil limit controller not; in action "appears. The output of the AND element 35 stands with the non-negative input of the AND element 37 and its output the transmitter device 19 via the AND gate 34 in connection that in the absence of Output signal at the threshold switches 18 of the working in parallel, with their Outputs with the negated inputs of the AND gate 37 connected machines, and if the message "Valve open and surge limit controller not in operation" is present the valve 21 is automatically closed via the AND element 35.

By manual intervention, both the setpoint adjustment device 20 in the direction of "speed increase" or "speed decrease" as well as the encoder device 19 can be moved in the "open" or "closed" direction.

The AND gates 32 and 34 prevent a reduction in speed or closing the relief valve 21 by hand is possible as long as the surge limit control is engaged. The OR gates 33 and 31 are used to link the different Adjustment commands for one of the relief valve 21 or for increasing the speed brought about by hand or by surge limit control.

It should be noted that the closing of the relief valve 21 with a such speed takes place that the permissible in the pressure or quantity control circuit Control quality criteria of this controlled variable are not exceeded.

1!; It is possible to set up with electrical and / or pneumatic and / or hydraulic devices.

The invention is not bound to the circuit diagrams shown. So the members 11 to 15 and 26 to 30 comprehensive part of the device FIGS. 3 and 4, which are shown again separately in FIG. 5, correspond accordingly FIGS. 6 to 8 may be embodied in a varied manner.

According to Fig. 5, this is in PiC. 5 between the speed measuring element 11 and the mixing point 13 lying nonlinear element 12 removed and between the summing element 30 and the mixing point 13 is a correspondingly designed non-linear link 12 arranged.

According to Fig. 7; instead of the one in F £. 5 with all arithmetic links 15; 28; 29 connected summing element 30 only with the arithmetic elements 28; 29 connected Summing element 30 is not arranged between the linear element 12 and the mixing point 13 and the computing element 15 is directly connected to the mixing point 13.

According to Fig. 8, the non-linear member 12 is in the connection between of the arithmetic unit 15 and the mixing point 13 are provided and the speed sensor 11 staht directly with the summing member 30 in connection.

The respective intake temperature T1 and the respective Corrections of the surge limit adapted to the suction pressure p1 are not proportional to the corrections to the pressure p2 Signal via a summing element 30, but via an identical summing element that of the Speed proportional signal applied; will. Furthermore, the intake temperatures Corrections of the surge limit taking into account T1 and the suction pressures p1 are omitted, if these values are constant and the design of the non-linear element is based be placed or it is not necessary, the compressor at different To operate in external conditions close to the surge line. In the last case, the replica would the surge limit the most unfavorable operating conditions of the compressor that occur correspond.

Claims (11)

Patent claims: 1. Procedure to prevent pumping of variable-speed axial compressors, who work on pressure or quantity-regulated networks and their drive machines, z. B. Turbines, with a speed controller and a setpoint adjustment device are equipped, characterized in that the speed of the or dur in the Axial compressor (5) reaching near the surge limit (1 to 4) to connect the Exceeding the surge limit is increased and that is more due to the increase in speed The amount of laser conveyed is blown off in a manner known per se or into the suction channel of the axial compressor or compressors that come in the vicinity of the pump collar, if necessary is cooled, blown around. 2. The method according to claim 1, characterized in that the pressure (p2) hirter the axial compressor (5) with a below the surge limit the respective speed (n) or the respective amount of gas delivered (m) of an axial compressor formed, the function p2 "= f (m, p1, T1) + k2 = k1. f (n, p1, T1) + k2 following Size is compared and in the state p2> p2 "the speed of the axial compressor is increased until the state p2 # p2 "is reached. @. Method according to claim 2, characterized in that the or the blow-off or bypass valves (21) are closed after the state p2 # p2 " is reached in all axial compressors regulated with respect to the surge limit. 4. experience according to one of claims 1 to 3, characterized in that that the variable p2 "with change in temperature T1 and the pressure p1 of the function p2 "= f (m, p1, T1) + k2 = k1 following f (n, p1, T1) + k2 is corrected. 5. Device for performing the method according to one of the claims 1 to 3, characterized in that one which detects the speed of the axial compressor (5) Measuring element (11) acts with its output on a non-linear element (12) which is a the function P2 = k1 f (n) or p2 "= k1 f (n) + k2 corresponding signal to the mixing point (13) gives, and that a pressure measuring element (14) measuring the compressor outlet pressure its output signal via a computing element (15) also to the mixing point (13) can act and that the result of the two signals at the iiii.schstelle (13) resulting difference signal via a diode (17) and an amplifier (16) to a Threshold switch (18) acts, which in the addressed state via intermediate links causes both an increase in the speed of the drive machine (6), and that The relief valve (21) opens to such an extent that the increase in speed resulting Mehrförderun the amount of gas is blown off. 6. Device according to claim 5, characterized in that the output signal a temperature measuring element measuring the temperature of the gas upstream of the compressor (26) via a programmer which receives its reference variable from the speed measuring element (11) equipped computing element (28) and the output signal of the pressure of the gas in front of the compressor (5) measuring pressure measuring element (27) via its reference variable arithmetic element (29) obtained from the speed measuring element (11) in a summing element (30) added to the signal of the arithmetic unit (15) originating from the compressor final pressure and the output of the summer (30) is fed to the table station (139) will. 7. ßinrichtunr according to claim 5 or 6, characterized in that rekenn the output of the threshold switch (18) via an OR gate (33) with a transmitter device (19) (adjustment potentiometer) is connected in such a way that there is an output signal the threshold switch (18) causes the relief valve (21) to open and that continue the output of the threshold switch (18) with the negated input of a AND gate (34) is connected, interrupted by the closing of the relief valve (21) or is prevented and also the output of the threshold switch (18) with the negated input of an AND gate (35) is connected to the other input the non-closed state coming from the signal transmitter (36) of the valve (21) of the valve (21) indicating signal is performed, and thus at the output of this AND element (35) the message "Valve open and surge limit controller not in action" appears. 8. Device according to claim 7, characterized in that the output of the AND element (35) with the non-negated input of one with the threshold switch (18) of the parallel machines connected AND gate (37) and its output with the Transmitter device (19) (adjustment potentiometer) via which the shut-off valve is closed (21) interrupting or preventing AND element (34) is connected in such a way that that in the absence of an output signal at the threshold switches (18) the parallel working Machine the outputs of the same with the negated inputs of the AND gate (37) for the parallel machines are connected and if the message "Valve on and surge limit controller not in action "the relief valve (21) via the former AND element (35) is closed. 9. Device according to one of claims 5 to 8, characterized in that that instead of one between the speed measuring element (11) and the mixing point (13) arranged, non-linear member (21) another correspondingly designed non-linear element between the summing element (30) and the mixing point (13) is provided is. 10. Device according to one of claims 6 to 3, characterized in that that instead of the summing element connected to all arithmetic units (15; 28; 29) (30) a summing element connected only to the computing elements (28; 29) between the non-linear element (12) and the mixing point (13) is arranged and the computing element (15) is directly connected to the mixing point (13). 11. Device according to one of claims 5 to 8, characterized in that that the non-linear element (12) in the connection between the arithmetic element (15) and the mixing point (13) is provided and the speed measuring element (11) directly is in communication with the summing element (30).