際際滷

際際滷Share a Scribd company logo

Technical Review-NO.6

A
Abbas Mohajer

1) MAPNA TURBINE developed a dynamic simulator to model centrifugal compressor systems and test anti-surge control strategies to prevent damage. 2) A modular, non-linear dynamic model was created in FORTRAN to simulate the compression system performance during startup, operation, and shutdown. 3) The model was validated using experimental test bench data and field data from gas plants to accurately model the complex, non-linear behavior of the compressor and ancillary equipment under transient conditions.

1 of 5
Download to read offline
0$31$ 7XUELQH 2FWREHU 13 3 Compression Systems Dynamic Simulator for Anti-Surge Control System Design Development Introduction S ince compression systems serve as major, expensive and critical elements in most plants in the oil and gas industry, it is essential to protect them against potential damages caused by a dangerous dynamic phenomenon: Compressor Surge! Several studies and research activities have been conducted to develop knowledge in design and optimization of compressor anti -surge control system. MAPNA TURBINE, as a major manufacturer of turbo-machines, especially centrifugal compressors, in Iran and in the region, planned to develop the required tools in this area. The objective of this project was to develop a simulator for compression systems dynamic behavior. To serve this purpose, a modular dynamic model of a centrifugal compressor and its surrounding process equipment was developed. A non-linear one-dimensional model provides a description of the compression system performance during start-up, normal operation and emergency shutdown which can be used to test control strategies and logics. Several screenshots of the compression system dynamic simulator are shown in Figures 1, 2 and 3. Figure 1: Compression Plant Simulator Overview
0$31$ 7XUELQH 2FWREHU 14 Compression System Most sectors of the oil and gas industry require expensive compression facilities for different applications such as transmission, storage, gas gathering, gas export, gas injection and LNG. The majority of compression systems employ centrifugal compressors driven by gas turbines or electric motors. These critical systems must be carefully protected to achieve a high level of production sustainability and operational reliability. Cost of damages to FRPSUHVVRU VVWHPV FDQ OHDG WR VLJQLFDQW capital losses and long plant downtimes. Taking into account various design and performance requirements of centrifugal compressors depending on the industry and application, MAPNA TURBINE has provided the capability and technical know-how in the design and manufacture of compressors with conspicuous major advantages compared with other manufacturers in the market. The FRPSUHVVRUV DUH GHVLJQHG IRU RZ UDWHV LQ a wide range of 500 to 30000 sm3 /min and discharge pressures from 2 to 200 bars. 6SHFLFDWLRQV IRU WSLFDO FRPSUHVVRUV DUH listed in Table 1. Compressor type Number of stage(s) Speed (rpm) Impeller diameter (mm) Commercial output Pressure ratio 0 3 5000 28 1.4 0 2 5000 835 39 0 3 5000 835 1.52 MCC-C5-200-3395 6 596 2.83 0 4 6100 8.558 2.08 MCC-C4-146-4592 4 8200 8.558 2.05 Compressor control system must provide the assurance that the compressors are not subjected to damage while undergoing rapid dynamic events. During transient condition, a centrifugal compressor may come close to surge; a violent instability that often damages the compressor due to excessive stress and vibration. Anti-surge control systems are therefore employed to be activated to prevent surge. Anti- surge regulators are used in multi- processor control systems of mechanical drives to control gas compressor units. The anti-surge regulation consists of three functional blocks: diagnostic block of pre- surge conditions, block of surge reserve calculation and ASV (Anti-Surge Valve) control block. Typical control scenarios that have to be considered are process control, starting and stopping, and emergency shutdowns. The possibilities of practically testing anti-surge control strategies and logics on a full scale compressor are limited because of the consequences of such failures. Moreover, the experimental facility can be very expensive to set up. In other words, experimenting with large industrial compressors controllers is both risky and expensive. Albeit, the reliability of the control system must be examined before the Site Acceptance Test begins. To get it materialized, it is necessary to simulate the plants real conditions by simulation tools to verify the system design and to test the control logic across the whole operating range of the compressor SHUIRUPDQFH 7KHUHIRUH D KLJK GHOLW compression system dynamic simulation environment was developed by MAPNA TURBINE in order to design a control system with enhanced control capabilities. 7DEOH 0$31$ 785%,1( WSLFDO FRPSUHVVRUV VSHFLFDWLRQV
0$31$ 7XUELQH 2FWREHU 15 Dynamic Simulation of the Compression System The modern surge control design process often involves analyses using dynamic simulation of the compression system involved. The dynamic simulator enables the designer to test new control logics and see the results before implementing it on the governor system. This will increase the reliability and prevent undesirable costs resulting from practical trial and error processes. Having such simulators is deemed to be essential to serve other applications during all stages of the product life cycle, including but not limited to the following: To simulate real critical conditions in a virtual environment Site Acceptance Test (SAT) and Factory Acceptance Test (FAT) expected capabilities Educational tool to train operators and improve their skills before and after start-up 7R VLPXODWH SDUDOOHO FRQJXUDWLRQ operation and develop a load sharing system To conduct What If analyses Plant design optimization at Front End Engineering Design (FEED) stage The project tasks were developed in the four following stages: 1. Review the existing models for Dynamic Simulation of Compression Systems 2. Create a dynamic model for a desired compression system 3. Develop the model in FORTRAN programming language 4. Validate the model with experimental DQG HOG GDWD Figure 2: Typical Compressor Performance Curve
0$31$ 7XUELQH 2FWREHU 16 A sketch of the system under consideration is presented in Figure 3. The system is composed of the compressor and the surrounding pieces of equipment which are characterized by complex non-linear behavior. In addition, the driver might have complex dynamics which in turn affects the system. The model also includes a cooler for gas cooling, a scrubber for liquid draining, and a recycle line with a control valve for anti- surge control. Figure 3: Sketch of Compression System Comprising Compressor and Ancillary Equipment Themodelisone-dimensionalandsimulates SUHVVXUH WHPSHUDWXUH DQG PDVV RZ IRU DOO system components, and also compressor shaft speed. It is derived in a modular fashion,usingmass,momentumandenergy balance. Compressor characteristics maps from the compressor test bench are used to determine compressor pressure ratio DQG HIFLHQF 7KH PDWKHPDWLFDO PRGHO has been developed in FORTRAN and YHULHG DJDLQVW FRPSDQ揃V WHVW EHQFK experimental results and those produced RXW RI WKH HOG GDWD REWDLQHG IURP 6RXWK Pars 19th phase gas export plant. Qualitative information on compressor behavior may be obtained by testing compressors. The information obtained on these machines may be used to better understand the physical phenomena and to validate mathematical models. In MAPNA TURBINE, a performance and mechanical running test bench for centrifugal compressors Figure 4 had been already launched in 2014. Numerous machines of various capacities have been successfully tested at the local test bench. The test facility is equipped with a 2.5 MW driving electromotor and a variable speed Compressor Dynamic Test
0$31$ 7XUELQH 2FWREHU gearbox generating an output speed varying from 0 to 5000 rpm. Compressors of higher velocity are tested using an accessory set-up gearbox coupled to the output shaft of this main gearbox. All test bench equipment pieces and inlet/outlet accessories as well as test instructions follow the requirements of PTC10. In particular, the facility was designed to perform compressor steady state characterization, such as specifying performance map and identifying compressor surge point. This facility has also been used to carry out dynamic analyses and dynamic simulation validation aiming at investigation of compressor behavior in transient unsteady conditions. Figure 4: A Photograph of Compressor Test Bench

More Related Content

Technical Review-NO.6

  • 1. 0$31$ 7XUELQH 2FWREHU 13 3 Compression Systems Dynamic Simulator for Anti-Surge Control System Design Development Introduction S ince compression systems serve as major, expensive and critical elements in most plants in the oil and gas industry, it is essential to protect them against potential damages caused by a dangerous dynamic phenomenon: Compressor Surge! Several studies and research activities have been conducted to develop knowledge in design and optimization of compressor anti -surge control system. MAPNA TURBINE, as a major manufacturer of turbo-machines, especially centrifugal compressors, in Iran and in the region, planned to develop the required tools in this area. The objective of this project was to develop a simulator for compression systems dynamic behavior. To serve this purpose, a modular dynamic model of a centrifugal compressor and its surrounding process equipment was developed. A non-linear one-dimensional model provides a description of the compression system performance during start-up, normal operation and emergency shutdown which can be used to test control strategies and logics. Several screenshots of the compression system dynamic simulator are shown in Figures 1, 2 and 3. Figure 1: Compression Plant Simulator Overview
  • 2. 0$31$ 7XUELQH 2FWREHU 14 Compression System Most sectors of the oil and gas industry require expensive compression facilities for different applications such as transmission, storage, gas gathering, gas export, gas injection and LNG. The majority of compression systems employ centrifugal compressors driven by gas turbines or electric motors. These critical systems must be carefully protected to achieve a high level of production sustainability and operational reliability. Cost of damages to FRPSUHVVRU VVWHPV FDQ OHDG WR VLJQLFDQW capital losses and long plant downtimes. Taking into account various design and performance requirements of centrifugal compressors depending on the industry and application, MAPNA TURBINE has provided the capability and technical know-how in the design and manufacture of compressors with conspicuous major advantages compared with other manufacturers in the market. The FRPSUHVVRUV DUH GHVLJQHG IRU RZ UDWHV LQ a wide range of 500 to 30000 sm3 /min and discharge pressures from 2 to 200 bars. 6SHFLFDWLRQV IRU WSLFDO FRPSUHVVRUV DUH listed in Table 1. Compressor type Number of stage(s) Speed (rpm) Impeller diameter (mm) Commercial output Pressure ratio 0 3 5000 28 1.4 0 2 5000 835 39 0 3 5000 835 1.52 MCC-C5-200-3395 6 596 2.83 0 4 6100 8.558 2.08 MCC-C4-146-4592 4 8200 8.558 2.05 Compressor control system must provide the assurance that the compressors are not subjected to damage while undergoing rapid dynamic events. During transient condition, a centrifugal compressor may come close to surge; a violent instability that often damages the compressor due to excessive stress and vibration. Anti-surge control systems are therefore employed to be activated to prevent surge. Anti- surge regulators are used in multi- processor control systems of mechanical drives to control gas compressor units. The anti-surge regulation consists of three functional blocks: diagnostic block of pre- surge conditions, block of surge reserve calculation and ASV (Anti-Surge Valve) control block. Typical control scenarios that have to be considered are process control, starting and stopping, and emergency shutdowns. The possibilities of practically testing anti-surge control strategies and logics on a full scale compressor are limited because of the consequences of such failures. Moreover, the experimental facility can be very expensive to set up. In other words, experimenting with large industrial compressors controllers is both risky and expensive. Albeit, the reliability of the control system must be examined before the Site Acceptance Test begins. To get it materialized, it is necessary to simulate the plants real conditions by simulation tools to verify the system design and to test the control logic across the whole operating range of the compressor SHUIRUPDQFH 7KHUHIRUH D KLJK GHOLW compression system dynamic simulation environment was developed by MAPNA TURBINE in order to design a control system with enhanced control capabilities. 7DEOH 0$31$ 785%,1( WSLFDO FRPSUHVVRUV VSHFLFDWLRQV
  • 3. 0$31$ 7XUELQH 2FWREHU 15 Dynamic Simulation of the Compression System The modern surge control design process often involves analyses using dynamic simulation of the compression system involved. The dynamic simulator enables the designer to test new control logics and see the results before implementing it on the governor system. This will increase the reliability and prevent undesirable costs resulting from practical trial and error processes. Having such simulators is deemed to be essential to serve other applications during all stages of the product life cycle, including but not limited to the following: To simulate real critical conditions in a virtual environment Site Acceptance Test (SAT) and Factory Acceptance Test (FAT) expected capabilities Educational tool to train operators and improve their skills before and after start-up 7R VLPXODWH SDUDOOHO FRQJXUDWLRQ operation and develop a load sharing system To conduct What If analyses Plant design optimization at Front End Engineering Design (FEED) stage The project tasks were developed in the four following stages: 1. Review the existing models for Dynamic Simulation of Compression Systems 2. Create a dynamic model for a desired compression system 3. Develop the model in FORTRAN programming language 4. Validate the model with experimental DQG HOG GDWD Figure 2: Typical Compressor Performance Curve
  • 4. 0$31$ 7XUELQH 2FWREHU 16 A sketch of the system under consideration is presented in Figure 3. The system is composed of the compressor and the surrounding pieces of equipment which are characterized by complex non-linear behavior. In addition, the driver might have complex dynamics which in turn affects the system. The model also includes a cooler for gas cooling, a scrubber for liquid draining, and a recycle line with a control valve for anti- surge control. Figure 3: Sketch of Compression System Comprising Compressor and Ancillary Equipment Themodelisone-dimensionalandsimulates SUHVVXUH WHPSHUDWXUH DQG PDVV RZ IRU DOO system components, and also compressor shaft speed. It is derived in a modular fashion,usingmass,momentumandenergy balance. Compressor characteristics maps from the compressor test bench are used to determine compressor pressure ratio DQG HIFLHQF 7KH PDWKHPDWLFDO PRGHO has been developed in FORTRAN and YHULHG DJDLQVW FRPSDQ揃V WHVW EHQFK experimental results and those produced RXW RI WKH HOG GDWD REWDLQHG IURP 6RXWK Pars 19th phase gas export plant. Qualitative information on compressor behavior may be obtained by testing compressors. The information obtained on these machines may be used to better understand the physical phenomena and to validate mathematical models. In MAPNA TURBINE, a performance and mechanical running test bench for centrifugal compressors Figure 4 had been already launched in 2014. Numerous machines of various capacities have been successfully tested at the local test bench. The test facility is equipped with a 2.5 MW driving electromotor and a variable speed Compressor Dynamic Test
  • 5. 0$31$ 7XUELQH 2FWREHU gearbox generating an output speed varying from 0 to 5000 rpm. Compressors of higher velocity are tested using an accessory set-up gearbox coupled to the output shaft of this main gearbox. All test bench equipment pieces and inlet/outlet accessories as well as test instructions follow the requirements of PTC10. In particular, the facility was designed to perform compressor steady state characterization, such as specifying performance map and identifying compressor surge point. This facility has also been used to carry out dynamic analyses and dynamic simulation validation aiming at investigation of compressor behavior in transient unsteady conditions. Figure 4: A Photograph of Compressor Test Bench