Steady state signal to anti surge control valve % p s. Antisurge systems for axial compressors turbomachinery. A surge avoidance system anti surge control consists of a recycle loop with a fast acting valve anti surge valve. Despite all these discussions there was a serious lack of the basic scheme of anti surge control. Therefore the control system must also decouple the capacity control from the anti surge control to avoid possible instability.
Anti surge control results in standard deviation of master pressure fluctuation compared to preshutdown operation reduced from 0. Vary recycle blowoff to control compressor on surge control line surge control basics ft uic pt pt fy tt pt tt pic sic st. The only obstacle for a traditional industrial mpc implementation for anti surge control is the stringent realtime requirements of compressor anti surge control, which can have execution cycle times down to 40 ms. Centrifugal compressor antisurge control algorithm in unit. Surge cycles occur keywordsantisurge, control, compressor, pid control. The set point of the pi controller is a flow rate that lies on the control line. Surging can cause the compressor to overheat to the point at which the maximum allowable temperature of the unit is exceeded. Fine points of compressor surge control control global. Centrifugal air compressor controls are supposed to be set conservatively to avoid surge.
Jul 05, 2014 series 3 plus antisurge controller 17 im301 6. For this reason the anti surge recycle connection and anti surge control valve shall be located upstream of the check valve as close as practical to the compressor discharge connection. Anti surge controller working principle instrumentation. Compressor loadsharing control and surge detection techniques wayne jacobson global technology manager compressor controls corporation des moines, ia, usa medhat zaghloul regional manager abu dhabi compressor controls corporation al reem island, abu dhabi, uae michael tolmatsky director research and development. When configured as a compressor antisurge control only, the 505cc2 can be programmed to control and protect a one or twoloop compressor set being driven by a motor or steam turbine. It can even cause compressor surge since the interaction starts at the surge control line. The surge usually starts in one stage of a multistage compressor and can occur very rapidly. Surge control spc provides fully integrated multiloop, multiplebody compressor surge control.
In this control strategy, a control line is defined at some distance from the surge line, and operating point is kept to the right of control line. Centrifugal compressor antisurge control algorithm in unit control pan posted in chemical process simulation. If a compressor goes into surge, surge will be detected when the operating point crosses the surge detection line sdl. The paper emphasizes the interrelation between the process system and the compressor.
The simpler algorithms used, the bigger safety margins required and, therefore. Process control ccc compressor controls corporation. Compressor surge prevention control implemented on. The surge control algorithm executes in less than 25 ms. When flow element installed at discharge line, discharge flow shall be converted to suction flow by installing pressure transmitter at both lines. The next g eneration of control technology compressor surge prevention control implemented on yokogawa stardom. Centrifugal compressor surge, modeling and identification. Antisurge control ccc compressor controls corporation. Anti surge controller working principle instrumentation tools. If op is moving leftward toward scl, your algorithm shall open anti surge valve asv. This allows the surge controller to be tuned for faster response than would be possible without this limit. Compressor anti surge nonlinear model predictive control. What is surging and choking in centrifugal compressor. Sep 05, 2017 for the love of physics walter lewin may 16, 2011 duration.
When a centrifugal compressor surges, there is an actual reversal of gas flow through the compressor impeller. Surge it is a phenomena accompanied by centrifugal compressors having continuous flow rate, gas path inside compressor flows having an acceptable value of eddies and vortices but if these eddies and vortices. This can occur when the mass flow of gas to the compressor falls below a critical level with a high pressure difference. Anti surge control system for centrifugal compressors part 3. Dot lined cooler dwg is requested by anti surge system and solid line coolers is requested by compressor process itself. Using active control a control system feeds back perturbations into the. When configured as a compressor anti surge control only, the 505cc2. Surge control problems have been around as long as the centrifugal compressor itself. Surge detection with ccs detection rateofchange method surge of the compressor can be stopped during the first cycle by opening of the. May 12, 2016 loop control fine points of compressor surge control compressor damage and costly production outages can be prevented by attention to surge curves, control strategies and valve response. Determination of parameters assigned to an antisurge. Now we will see how the surge starts in a compressor.
Determine the best anti surge, performance control approaches test decoupling control algorithms. Many different approaches have been taken to improve operating range to surge both in head and flow depending on what type of surge mechanism is present in the compressor system. These anti surge systems or surge control systems consist of one or two recycle lines around the compressor, which are equipped with fast acting valves that open when the compressor approaches the surge limit. Anti surge control systems these systems detect when a process compression stage is approaching to surge and subsequently take action to reverse the movement of the operating point towards the surge line sl. Our unique combination of surge prediction and antisurge control algorithms protect your machines with the smallest possible recycle rates. The anti surge controller imaginary operation protection line is surge control line. Control and operation of centrifugal gas compressors, with. Secondary pid loop overrides, and capacity control are not shown for clarity. The compressor application control package includes. Surging is a momentary back flow through the compressor from the discharge to the suction. Pid controller is used for controlling and stabilizing the system. This article explains surge phenomena and discusses why the anti surge protection system is a very important part of a compressor. Hi, i am emulating centrifugal compressor which is driven by variable speed gas turbine compressor antisurge control algorithm, load sharing control, and performance control is built in unit control panel of vendorthere is a flow element orifice installed at compressor suction. Model predictive control mpc is a common choice in the industry to solve such multivariable and constrained control problems.
Selector control yss proprietary algorithm the controlled object can be automatically switched over between two different factors, namely, flow rate and pressure. Anti surge control free download as powerpoint presentation. Multistage centrifugal compressor model and antisurge control strategy article in kongzhi yu juececontrol and decision 283. Nonlinear mpc, compressor modeling, antisurge control, variable speed drive. Sep 05, 2017 anti surge control system for centrifugal compressors part 5.
Evaluation of anti surge control concepts during esd 2. Pdf anti surge control of centrifugal compressor at pt. In newer air compressors, a surge control line is developed based on polytropic head, a pressure value normalized for temperature. The fastest and most dangerous phenomenon is compressor surge. For the purposes of this tutorial, the vertical axis becomes reduced head or hp. Multistage centrifugal compressor model and antisurge. Compressor loadsharing control and surge detection techniques.
Pdf surge control and dynamic behavior for centrifugal gas. A technique for the use of the certified gaseodynamic characteristics of a compressor and the equations of state of actual gases for determining the parameters assigned to an anti surge controller is presented. Finally, the developed surge control system was implemented on one of the compressor test rigs under study. Different control algorithms can be configured such as. An axial or centrifugal compressor can reverse flow in 0. The sds concerns the performance of a compressor system in a gas conditioning plant. Anti surge systems are therefore employed to be activated to prevent the unit for undergoing surge. There are many station events that can cause a centrifugal compressor to surge, such as interaction with other units, reciprocating compressor pulsations, and upset conditions like sudden. This is defined as the surge cycle of the compressor.
Surge detection with ccs detection rateofchange method surge of the compressor can be stopped during the first cycle by opening of the recycle valve and surge control line is moved to preselected position. Using a bounded feedback controller, surge limit cycles are stabilized in the desired setpoint. Single stage compressor control rockwell automation. To avoid surging anti surge controller is provided, while. Centrifugal compressors are widely used for natural gas transportation by increasing the pressure of the gas. An unsteady state model of material balance around the control.
Compressor loadsharing control and surge detection techniques wayne jacobson global technology manager compressor controls corporation des moines, ia, usa. Control of surge in centrifugal compressors by active. Anti surge control valve gas compressor free 30day. Erformance control ects performancepac process controller controls your plants main. In this article torque assisted anti surge control tasc, a compressor anti surge control system based on model predictive control mpc is presented. The 505cc2s control hardware consists of a ruggedized hardware platform designed for control room or skid mount locations. Also, surging can cause damage to the thrust bearing due to the rotor shifting back and forth from the active to the inactive side. This is the first of a threepart series by the author. During closedloop experiments the control system proved to be inadequate for surge suppression in the compression system. Steady state pressure in the piping system a er the check valve. Surge control design for centrifugal compressor systems.
Typically the pi proportional integral control algorithm will active and start to modulate the anti surge control valve if the compressor operates between the control line and the surge line. Pic uic ft pt tt pt tt anti surge valve suction valve capacity control compressor cooler. Oftentimes performance control and antisurge control can have conflicting control objectives and since both manipulate the compressors operating point, the interaction can result in an unstable process, and poor operational efficiencies. Apr 29, 2015 this is the first of a threepart series by the author. A typical system consists of pressure and temperature transmitters on the compressor suction and discharge lines, a flow differential pressure transmitter across the compressor flowmeter, an algorithm in the control system, and a surge control valve with corresponding accessories. The ccc antisurge controller accurately models the surge limit line for all operating conditions of the compressor. Tasc is implemented on an embedded system for the control of compressor stations with electrical variablespeed drives vsd which are used in applications such as natural gas transportation via pipelines.
Section 3 description of surge 31 surge versus stall surge is a dynamic instability that occurs in dynamic compressors. The perfect way to overcome this surge line would be to have a bypass valve that metered airflow down low in the engines rpm, enough to pass the needed amount. Centrifugal and axial compressors are susceptible to surge which can cause catastrophic damage to your turbomachinery train. This paper mainly describes the reasons for compressor surge and damage, and provide the traditional control method, which can not meet the growing needs, the improved control method, which according to the data using least squares curve to determine surge control regression equation and make the compressor operate safely by using the fuzzy pid control algorithm on the parameter adjustment. The results of the thesis demonstrate that better pressure control reduces the risk of surge. Avoidance control and active control are two strategies for compressor anti surge control 56. Compressor surge prevention control implemented on yokogawa. Normally, a polynomial equation is used to approach the control line. A feed forward control strategy, therefore, was recommended to improve transient behavior. A skilled technician surge tests the air compressor, and enters the surge control. When surge line is determined, ccs field engineer sets the csm values for.
We have an algorithm that will step the demand signal by a configurable amplitude, usually around 3%, when the surge valve is asked to open from fully closed position in order to minimize delays due to pressure saturation in the actuator, as well as seat and seal friction. These techniques are applicable to axial and centrifugal compressors with variable speed or guide. Industrial compressor antisurge computer control citeseerx. Thats where the anti surge rings opening is located. They reduced the standard deviation of pressure fluctuations and provided safe operation of compressor away from surge area as well as by control algorithm of pid. Abstractthe paper presents a compressor antisurge control system, that results. Procidia control solutions compressor surge control. Model predictive antisurge control of centrifugal compressors. The following simplified functional block diagram illustrates the features of the algorithm. Moreover, a cooler in the recycle line may have to be considered, to suitably control the suction temperature and thereby prevent the compressor from going into. Botros is a world authority on surge control design and analysis, and has focused his research activities on transient flow problems in complex systems, including centrifugal compressor surge phenomenon, pressure relief system dynamics, transients of twophase stratified. This article explains surge phenomena and discusses why the anti surge protection system is a very important part of a compressor surge.
Our controller combines both closed and open loop control responses to prevent surge without requiring a large control margin while minimizing recycling and unnecessary upsets to the process. Keywords anti surge, control, compressor, pid control, safety, fault tolerance, startup, esd. Compressor surge triggered by diffuser stall can be suppressed by. Surge detection with ccs detection rateofchange method surge of the compressor can be stopped during the first cycle by opening of the recycle valve and surge. Therefore, the control system, as well as the phenomenon of surge and stall is discussed. In the simulations the greitzer compression system model greitzer 1976 is used to. Ects powerful surge stopper control algorithm breaks the surge cycle immediately and prevents surge from occurring again. Antisurge control is an important control for safety of the compressor and it. An improperly designed surge control system can lead to multiple surge events increasing the risk to personnel safety and major damage to the compressor. Anti surge is witnessed when the flow to the centrifugal compressor is reduced or the density of the fluid entering the compressor is altered to greater extent, pressure is reduced to a lower extent. Mpc based algorithms with conventional control systems for. Em452 multibody, anti surge compressor controller the em452 series multibody anti surge controller is a proibus networkattached compressor controller system. The new method is explained and the results compared with.
Protecting a centrifugal compressor from surge pipeline. The anti surge system has to control the operating op point on the right of scl. Axial and centrifugal compressor control is exceptionally challenging due to the extraordinary speed and severity of problems, and the extreme consequences in terms of plant safety and performance. The active stabilization of compressor surge employing ambs in a machine is fully explored, from modeling of instability and controller design, to the implementation and experimental testing of the control algorithm in a speciallyconstructed, industrialsize centrifugal compression system. Compressor loadsharing control and surge detection. Pdf industrial compressor antisurge computer control. In willems 2000 active surge control of a centrifugal compressor is simulated and implemented on a gas turbine installation. Adding more safety margin to the surge control line would significantly affect compressor operational flexibility. The surge is starting with the instant flow reverses, shown in the above figure. Anti surge control system for centrifugal compressors part 5. Compressor surge has been discussed often on the forum with many posts dedicated to the subject. Evaluation of antisurge control concepts during esd. Compressor p figure 2 compressor surge control strategy the rate limiter function block rlm1 is configured to slow the closing of the recycle valve. The rlm should be set so as not to impede the opening of the recycle valve.
The instability is characterized by large limit cycle oscillations in compressor. Oftentimes performance control and antisurge control can have conflicting control objectives and since both manipulate the compressor s operating point, the interaction can result in an unstable process, and poor operational efficiencies. The distance between surge line and control line cannot. More efficient compressor operation is provided by eliminating unnecessary recycle. Moreover the interaction between pressure controller and surge controller can be avoided by. Centrifugal air compressor controls and sizing basics. This involved ramping open the anti surge valves at the initiation of a process shutdown. An algorithm that describes the operation of a dynamic compressor control system with anti surge valve is presented. A reliable control valve that functions consistently under the most severe conditions is absolutely essential to the protection of the compressor. It is a phenomena accompanied by centrifugal compressors having continuous flow rate, gas path inside compressor flows having an acceptable value of eddies and vortices but if these eddies and vortices.
Pdf model predictive antisurge control of centrifugal. Figure 31 shows a compressor map for a variablespeed centrifugal compressor. For example, a shutdown of the catalytic cracking unit in a refinery can cost. Ad ram pid id f im301 series 3 plus antisurge controller for axial and centrifugal compressors publication im301 6. The paper presents a compressor anti surge control system, that results in maximizing compressor throughput with pressure standard deviation reduction, increased safety margin between design point and surge limit line and avoiding possible machine. Compressor antisurge control yokogawa electric corporation. Moore has developed a wellproven compressor control algorithm utilizing tested features to protect a compressor against surges, while simultaneously optimizing the efficiency of the compressor. Dimitrios and george have inspected on the various mechanisms of anti surge valves. Centrifugal compressor surge, modeling and identification for.
Antisurge protection system for compressors turbomachinery. Control and operation of centrifugal gas compressors, with an. Anti surge control of centrifugal compressor at pt. Surge is an inherent phenomenon in a centrifugal compressor, defined as reversal of fluid flow which can possibly damage the machine. Antisurge control is an important control for safety of the compressor and it can keep the compressor always running in the. Description of compressor surge, and methods to prevent surge from occurring. Sep 23, 2016 this is defined as the surge cycle of the compressor. Turbocompressor antisurge control, new solution for an old problem.
Opening the recycle valve lowers the resistance felt by the compressor. The improvement of antisurge control on air separation. The antisurge controller is one of the most critical turbomachinery control applications that protect a compressor from surge by continuously calculating the distance between the compressor s operating point and its surge limit line. Anti surge protection is provided by a control valve which will either exhaust the gas or vapor from the compressor into the atmosphere, or recirculate it back to the compressor inlet. This module incorporates petrotechs ieldproven conigurable anti surge control algorithm into a. When the control system detects the compressor approaching its surge limit, the anti surge. Anti surge curves fitted on compressor controller increased safety margin between design point of compressor and surge limit line by about 10%, 10. In this paper, a compressor anti surge nonlinear model predictive control system is presented.
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