Abstract:
The subject matter of this specification can be embodied in, among other things, a compressor anti-surge system that includes a first actuator configured to actuate a first valve of a first turbomachine, and a first controller at least partially integrated with the first actuator or the first valve, and comprising circuitry configured to perform at least one of a control operation or a protection operation for the first turbomachine.

Description:
TECHNICAL FIELD 
       [0001]    This specification relates to turbomachine control and protection systems. 
       BACKGROUND 
       [0002]    Compressors increase the pressure on a fluid. As gases are compressible, the compressor also reduces the volume of a gas. A compressor stall is a local disruption of the airflow in a gas turbine or turbocharger compressor. Axi-symmetric stall, also known as compressor surge, is a breakdown in compression resulting in a reversal of flow and the violent expulsion of previously compressed gas out in the direction of the compressor intake. This condition is a result of the compressor&#39;s inability to continue working against the already-compressed gas behind it. As a result, the compressor may experience conditions that exceed its pressure rise capabilities, or the compressor may become loaded such that a flow reversal occurs, which can propagate in less than a second to include the entire compressor. 
         [0003]    Once the compressor pressure ratio reduces to a level at which the compressor is capable of sustaining stable flow, the compressor will resume normal flow. If the conditions that induced the stall remains, the process can repeat. Repeating surge events can be dangerous, since they can cause high levels of vibration, compressor component wear and possible severe damage to compressor bearings, seals, impellers and shaft, including consequential loss of containment and explosion of hazardous gas. 
       SUMMARY 
       [0004]    In general, this document describes turbomachine protection systems. 
         [0005]    In a first aspect, a compressor anti-surge system includes a first actuator configured to actuate a first valve of a first turbomachine, and a first controller at least partially integrated with the first actuator or the first valve, and comprising circuitry configured to perform at least one of a control operation or a protection operation for the first turbomachine. 
         [0006]    Various embodiments can include some, all, or none of the following features. The first actuator can be configured to actuate the first valve through a mechanical coupler or a fluid circuit. The compressor anti-surge system can include a first field sensor configured to sense a first turbomachine parameter of the first turbomachine, wherein the first controller is further configured to receive the first turbomachine parameter from the first field sensor and perform at least one of a control operation or a protection operation for the first turbomachine, based at least in part on the received first turbomachine parameter. The valve can be a sliding stem turbomachinery control valve, rotary turbomachinery control valve, or a guide vane. The compressor anti-surge system can include an integral or adjacent heat exchanger in fluid communication with the valve and configured to cool fluids that are passed through the valve. The first controller can include a first communication port and can be configured to provide controller operations information through the first communications port, a second actuator configured to actuate a second valve of a second turbomachine, and a second controller at least partially integrated with the second actuator or the second valve, a second communication port configured to communicate with the first communication port and receive controller operations information, and comprising circuitry configured to perform at least one of a control operation or a protection operation for the second turbomachine based at least in part on the received controller operations information. The first controller can include a first communication port and is configured to provide controller operations information through the first communications port, a second actuator configured to actuate a second valve of the first turbomachine, and a second controller at least partially integrated with the second actuator or the second valve, a second communication port configured to communicate with the first communication port and receive controller operations information, and comprising circuitry configured to perform at least one of a control operation or a protection operation for the first turbomachine based at least in part on the received controller operations information. 
         [0007]    In a second aspect, a method of responding to compressor surge includes receiving at a first controller at least partially integrated with a first valve and from a first field sensor a first turbomachine parameter of a first turbomachine, determining by the first controller at least one of a control operation or a protection operation for the first turbomachine, based at least in part on the received first turbomachine parameter, and actuating by a first actuator at least partially integrated with the first valve or the first controller the first valve to perform the determined control operation or protection operation for the first turbomachine. 
         [0008]    Various implementations can include some, all, or none of the following features. The first actuator can be configured to actuate the first valve through a mechanical coupler or a fluid circuit. The valve can be a sliding stem turbomachinery control valve, rotary turbomachinery control valve, or a guide vane. At least one of the control operation or the protection operation for the first turbomachine can include actuating the first valve to control flow of fluids to an integral or adjacent heat exchanger in fluid communication with the valve and configured to cool fluids that are passed through the valve. The method can include providing by the first controller operations information through a first communications port, receiving at a second communications port of a second controller at least partially integrated with a second valve of a second turbomachine or a second actuator configured to actuate the second valve the controller operations information, and actuating by the second actuator the second valve perform at least one of a control operation or a protection operation for the second turbomachine based at least in part on the received controller operations information. The method can include providing by the first controller operations information through a first communications port, receiving at a second communications port of a second controller at least partially integrated with a second valve of the first turbomachine or a second actuator configured to actuate the second valve the controller operations information, and actuating by the second actuator the second valve perform at least one of a control operation or a protection operation for the first turbomachine based at least in part on the received controller operations information. 
         [0009]    The systems and techniques described here may provide one or more of the following advantages. First, a system can widen the turbomachine operating envelope. Second, the system can increase turbomachine safety. Third, the system can reduce of the effective valve size. Fourth, the system can reduce process time lags in the anti-surge system. Fifth, the system can improve the reliability and predictability of turbomachine system dynamic performance. 
         [0010]    The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings, and from the claims. 
     
    
     
       DESCRIPTION OF DRAWINGS 
         [0011]      FIG. 1  is a schematic diagram that shows an example of a prior art turbomachine system 
           [0012]      FIG. 2  is a schematic diagram that shows an example of a compressor system. 
           [0013]      FIG. 3  is flow chart that shows an example of a process for protecting a turbomachine system. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    This document describes systems and techniques for reducing turbomachine surge. In general, the turbomachine anti-surge systems described in the descriptions of  FIGS. 2-3  combine all or some of one or more fast, high dynamic performance electrically actuated anti-surge valves, electronic controls fully or partially integrated into the valve assembly and executing surge prevention and surge protection control algorithms, compact heat exchangers adjacent to the anti-surge valves to cool the medium flowing through the anti-surge valves, and reducing process time lag in the anti-surge control loop. 
         [0015]    Compressor systems, as commonly used in gas transmission compressor stations, petro-chemical refining and processing installations, for example, can undergo a potentially destructive phenomenon called “surge”. The operational status of compressor systems can be represented by an operating map with axes representing changes in pressure (deltaP) and changes in flow (deltaQ). Surge occurs when, at a certain compressor head, the flow-rate is reduced to the extent that the operating conditions approach the points along the operating map where deltaP/deltaQ=0. These points appear on the operating map as a line sometimes referred to as the “surge line”. Upon further reduction of the flow-rate, the operating point of the compressor will oscillate between a point left and right of this surge line. The oscillation can cause undesired motion of the compressor blades and the drive shaft such that the blades contact the stators within the compressor which can cause catastrophic damage in a very short time period. 
         [0016]      FIG. 1  is a schematic diagram that shows an example of a prior art turbomachine system  100 . In  FIG. 1 , the turbomachine system  100  is illustrated as a centrifugal compressor that includes a compressor  102   a  and a compressor  102   b  that are driven by a prime mover  104  (e.g., a motor). The compressors  102   a ,  102   b  pressurize a gas received at an inlet  106  (e.g., a suction port) and discharge the pressurized gas at a discharge  108  (e.g., an outlet port). A process gas cooler  107  (e.g., a heat exchanger) cools the gas before it flows out a discharge  109 . 
         [0017]    To prevent surge conditions, the system  100  commonly includes a controller  110 , a hot recycle valve  112  controlling forward flow along a hot recycle conduit  114 , a cold recycle valve  116  controlling return flow along a cold recycle conduit  118 , and an actuator bypass loop with a gas inter-cooler  107  (heat exchanger). A fluid actuator  113  (e.g., hydraulic, pneumatic) is configured to actuate the hot recycle valve  112 , and a fluid actuator  117  is configured to actuate the cold recycle valve  116 . 
         [0018]    The controller  110  is configured to monitor either one or a plurality of a collection of surge parameter values. The surge parameter values are based on measurement signals received from a collection of system sensors and feedback devices. In the illustrated example, the controller  110  receives measurement signals from a flow sensor  130   a , a suction pressure sensor  130   b , and a discharge pressure sensor  130   c.    
         [0019]    If the controller  110  determines that a surge event is occurring, the controller  110  may directly or indirectly control a safeguard operation. For example, the controller  110  may trigger compressed gas at the discharge  108  to flow back to the inlet  106  through the cold recycle valve  116  to relieve the surge condition. In another example, the controller  110  may trigger uncompressed gas at the inlet  106  to flow forward to the discharge  108  through the hot recycle valve  112  to relieve the surge condition. 
         [0020]      FIG. 2  is a schematic diagram that shows an example of a compressor system  200 . In  FIG. 2 , the turbomachine system  200  is illustrated as a centrifugal compressor that includes a compressor  202   a  and a compressor  202   b  that are driven by a prime mover  204  (e.g., a motor). The compressors  202   a ,  202   b  pressurize a gas received at an inlet  206  (e.g., a suction port) and discharges the pressurized gas at a discharge  208  (e.g., an outlet port). A process gas cooler  207  (e.g., a heat exchanger) cools the gas before it flows out a discharge  209 . 
         [0021]    A flow sensor  230   a  is configured to measure inlet gas flow. A suction pressure sensor  230   b  is configured to measure gas pressure at the inlet  206 . A discharge pressure sensor  230   c  is configured to measure gas pressure at the discharge  208 . The inlet  206  is in fluid communication with the discharge  208  through a recycle valve  212  and a gas cooler  250  (e.g., heat exchanger). In some embodiments, the recycle valve can be a sliding stem turbomachinery control valve, a rotary turbomachinery control valve, a guide vane, or any other appropriate turbomachine valve. 
         [0022]    In the example compressor system  200 , an electric actuator  213  is configured to actuate the recycle valve  212 . The electric actuator  213  is an all-electric, high performance actuator. In some embodiments, the electric actuator  213  can start moving the recycle valve  212  more quickly (e.g., about 25 mS typical) than is possible with the fluid actuators  113  and  117  of  FIG. 1 . In some embodiments, the electric actuator  213  can move the recycle valve  212  from closed to fully open in about 0.3 to 0.6 seconds, although in some embodiments longer times may occur when actuating larger valves. In some embodiments, the electric actuator  213  may actuate the recycle valve  212  through a mechanical coupler or a fluid circuit. 
         [0023]    In some embodiments, use of the electric actuator  213 , rather than the relatively slower fluid actuators  113  and  117  of  FIG. 1  allows the compressor system  200  to be operated more efficiently than the compressor system  100 . In general, the closer that the compressor systems  100 ,  200  can be operated on the operating map to the deltaP/deltaQ surge line without actually reaching zero, the more efficient the compressor systems  100 ,  200  can be. However, to prevent the flow-rate from being reduced to the extent that the operating conditions actually reach a point along the operating map where deltaP/deltaQ=0, safety margins away from the surge line are generally used. The magnitudes of these safety margins are at least partly proportional to the amount of time needed for their corresponding compressor systems to take corrective, anti-surge actions before deltaP/deltaQ reaches zero. Use of the electric actuator  213  reduces the amount of time needed to respond to conditions that are indicative of surge (e.g., compared to the fluid actuators  113  and  117 ), and allows the compressor system  200  to be operated safely closer to the surge line. By operating closer to where deltaP/deltaQ=0, the compressor system  200  can operate more efficiently than the compressor system  100 . 
         [0024]    In some embodiments, the recycle valve  212  can be a high turn down valve that can be modulated near the fully closed position without causing damage to the internal metering elements of the recycle valve  212  due to high throttling conditions. In some embodiments, the recycle valve  212  can includes noise reduction trim, either within the recycle valve  212  or externally, depending upon operational requirements. 
         [0025]    To prevent surge conditions, the electric actuator  213  of the example compressor system  200  includes an at least partly integrated anti-surge controller configured to receive surge parameter values, calculate proximity to surge control line, and take corrective control actions. The surge parameter values are based on measurement signals received from a collection of system sensors and feedback devices. In the illustrated example, the electric actuator  213  receives measurement signals from the sensors  230   a - 230   c.    
         [0026]    To protect compressor from repeated surge, the electric actuator  213  of the example compressor system  200  includes an at least partly integrated surge detection system configured to receive surge parameter values, detect surge conditions, and/or take corrective safety actions. The surge parameter values are based on measurement signals received from a collection of system sensors and feedback devices. In the illustrated example, the electric actuator  213  receives measurement signals from the sensors  230   a - 230   c . In some embodiments, different and/or additional sensors may be used (e.g., temperature, torque, speed, vibration). 
         [0027]    The fully integrated surge controller of the electric actuator  213  of the example compressor system  200  is programmed and dynamically matched to the characteristics of the recycle valve  212  and the flow measurement system of the example compressor system  200  (e.g., the sensors  230   a - 230   c ) such that the total system dynamics of the compressor system  200  are well controlled and predictable. 
         [0028]    If the electric actuator  213  determines that a surge event is occurring, the electric actuator  213  may directly or indirectly control a safeguard operation. For example, the electric actuator can actuate the recycle valve  212  to allow compressed gas at the discharge  208  to flow back to the inlet  206  through the recycle valve  212  and the gas cooler  250  to relieve the surge condition. In another example, the electric actuator  213  may provide signals that can be used to trigger other remedial actions, for example, such as a controlled reduction or shutdown of the prime mover  204 . In some embodiments, the electric actuator  213  may also include functions such as surge control, choke control, steam turbine extraction control, gas turbine speed control, steam turbine speed control, compressor guide vane capacity control, compressor inlet throttle valve capacity control, or combinations of these and/or any other appropriate functions for compressor system control. 
         [0029]    In some embodiments, the surge controller of the electric actuator  213  can include a communication port that is configured to provide controller operations information through the communications port. A second actuator can be configured to actuate a second valve of a second turbomachine, and a second controller can be at least partially integrated with the second actuator or the second valve. The second controller can include a second communication port configured to communicate with the first communication port and receive controller operations information, and include circuitry configured to perform at least one of a control operation or a protection operation for the second turbomachine based at least in part on the received controller operations information. For example, the electric actuator  213  may provide information to an electric actuator of another compressor system. 
         [0030]    In some embodiments, the surge controller of the electric actuator  213  can include a communication port that is configured to provide controller operations information through the communications port. A second actuator can be configured to actuate a second valve of the compressor system  200 , and a second controller can be at least partially integrated with the second actuator or the second valve. The second controller can include a second communication port configured to communicate with the first communication port and receive controller operations information, and include circuitry configured to perform at least one of a control operation or a protection operation for the compressor system  200  based at least in part on the received controller operations information. 
         [0031]      FIG. 3  is flow chart that shows an example of a process  300  for protecting a turbomachine system. In some implementations, the process  300  can be used to protect the example compressor system  200  of  FIG. 2 . 
         [0032]    At  310 , a first controller at least partially integrated with a first valve receives a first turbomachine parameter of a first turbomachine from a first field sensor. For example, the compressor system  200  includes the electric actuator  213  which is configured to receive feedback from the sensors  230   a - 230   c.    
         [0033]    At  320 , the first controller determines at least one of a control operation or a protection operation for the first turbomachine, based at least in part on the received first turbomachine parameter. For example, the electric actuator  213  can receive feedback from the sensors  230   a - 230   c  and determine that a surge event is underway (e.g., deltaP/deltaQ is within the predetermined safety margin around the surge line). 
         [0034]    At  330 , the first actuator at least partially integrated with the first valve or the first controller actuates the first valve to perform the determined control operation or protection operation for the first turbomachine. For example, the electric actuator  213  can actuate the recycle valve  212  in an attempt to remedy the surge condition. In some implementations, at least one of the control operation or the protection operation for the first turbomachine can include actuating the first valve to control flow of fluids to an integral or adjacent heat exchanger in fluid communication with the valve and configured to cool fluids that are passed through the valve. For example, the recycle valve  212  can be actuated to allow compressed gasses to pass through the gas cooler  250  and on to the inlet  206 . 
         [0035]    In some embodiments, the process  300  can include providing, by the first controller, controller operations information through a first communications port, receiving, at a second communications port of a second controller at least partially integrated with a second valve of a second turbomachine or a second actuator configured to actuate the second valve, the controller operations information, and actuating, by the second actuator, the second valve perform at least one of a control operation or a protection operation for the second turbomachine, based at least in part on the received controller operations information. For example, the electric actuator  213  can provide control signals to another electric actuator of another compressor system  200  to cause another recycle valve to be actuated. 
         [0036]    In some embodiments, the process  300  can include providing, by the first controller, controller operations information through a first communications port, receiving, at a second communications port of a second controller at least partially integrated with a second valve of the first turbomachine or a second actuator configured to actuate the second valve, the controller operations information, and actuating, by the second actuator, the second valve perform at least one of a control operation or a protection operation for the first turbomachine, based at least in part on the received controller operations information. For example, the electric actuator  213  can provide control signals to another electric actuator of the compressor system  200  to cause another recycle valve of the compressor system  200  to be actuated. 
         [0037]    Although a few implementations have been described in detail above, other modifications are possible. For example, the logic flows depicted in the figures do not require the particular order shown, or sequential order, to achieve desirable results. In addition, other steps may be provided, or steps may be eliminated, from the described flows, and other components may be added to, or removed from, the described systems. Accordingly, other implementations are within the scope of the following claims.