 "Compressor surge control: Mitigating risk with simulation software")
Maximising compressor throughput and maintaining safety margins are high priorities for gas, energy and chemicals companies. These operations are highly complex and potentially hazardous. The measure of risk mitigation is the ability for process engineers to meet stringent demands and accurately address design, control and plant operability. There are many aspects of the operation that require rigorous analysis to control systems and response to disturbances.
Compressors, in particular, are an integral part of the production process. Avoiding costly repairs or overhauls due to destructive surge condition reduces downtime, saves equipment damage and ensures personnel are not exposed to harm. So, how can process engineers prevent catastrophic incidents to achieve an effective design for the control system?
Understanding the problem
Compressors are highly specialised pieces of equipment that are commonly custom designed, expensive to produce and costly to purchase. In refineries and petrochemical plants, they are used for different applications in the main and auxiliary process cycles. This could be a recycling compressor designed to provide a steady flow of process gas through a closed circuit to maintain the necessary process parameters in the plant units; feed compressors supplying process gas to the reactor; booster compressors or gas compressors managing fuel gas. They display an inherently transient behaviour and a small disturbance can quickly disrupt a compressor away from steady-state desired operating performance.
Surge occurs when the compressor outlet pressure is too high in relation to the flow through the compressor. If the compressor is not quickly controlled away from surge, the compressor can be damaged or even destroyed. An effective anti-surge control strategy is essential to protect the compressor. A proper surge control design is a mandatory design practice and seen as a measure of risk mitigation.
Process design has traditionally been executed using steady-state process simulators, albeit that today’s situation requires more capability and knowledge of the transient response of the process. Dynamic simulation used early in the design process can help to identify control issues more effectively and this results in better process design and smoother plant operations.
Compressors are subject to a variety of instabilities and upset conditions. Dynamic compressor models are a valuable tool in understanding upset and operational risk scenarios and have been made easier to adopt by integrating dynamic simulation closely within steady-state simulators. Using dynamic simulation, the process engineer can develop, evaluate and adjust control strategies for new and existing processes.
Dynamic modelling is a high value task requiring both expertise and experience. However, cutting-edge software makes the process simpler by automating dynamic modelling with a just few clicks to speed up model setup and enable more process engineers to perform compressor operability scenarios. All companies operating compressors, especially those processing gas in upstream and midstream will benefit from better reliability and reduced maintenance costs.
Improving compressor operability
Predicting process conditions that cause compressor to surge is a complex challenge. Understanding the process is fundamental to design an effective control strategy. The plant environment, for example, necessitates special considerations by the compressor designer to ensure a trouble-free operation after machine installation. The process control engineer must analyse all the variables, process dynamics and units interactions.
From the feasibility study, through to the front end engineering design (FEED) and detailed design, the engineer needs to consider many factors, including, compressor size, type, start-up, shutdown and much more. Process workflow and tighter time pressures to produce accurate, compliant, cost effective models for clients are other important considerations. Without the necessary tools and skills, companies suffer from inefficiencies in the overall design process.
Steady-state and dynamic models provide improved understanding of process dynamics and its interactions, which enable engineers to evaluate and adjust strategies before implementation. Using intuitive dynamic simulation software early in the design phase means the engineer can identify important operability and control issues quickly and more easily. Dynamic engineering software helps engineers to view the response of compressors to conditions that vary from steady-state. Robust and accurate dynamic modelling of compressor can prevent catastrophic equipment occurrences, such as compressor surge or flow reversal. The benefits of dynamic simulation help solve operational and design issues. Dynamic simulation is used as a validation tool, but also provides powerful insight into problem areas that would otherwise be overlooked.
Dynamic modelling has been made progressively easier to adopt by integrating dynamic simulation closely within steady-state simulators and introducing sample models to help engineers model their compressor installations without starting from the beginning.
Predicting success
When produced correctly, the dynamic simulation models provide a vital resource for the operating company and manufacturer to protect the compressor and avoid hazards, such as exposure of process gas to the surrounding atmosphere. Greater understanding of dynamic plant behaviour will result in tremendous improvements in control and improved uptime.
For many production processes in the oil and gas, energy and chemicals industries, knowing the precise dynamic response of a compressor is extremely important to purge errors or reduce risk in the design or operating process. By adopting state-of-the-art dynamic simulation software, engineers can eliminate the risk of equipment failure with improved design workflow and optimised performance, which can contribute significantly to the safety and profitability of the operation.
____________________________________________________________________________________________________________________
The author is the Senior Principal Business Consultant (Engg) APAC at AspenTech, one of the world's leading suppliers of software that optimises process manufacturing
Compressors, in particular, are an integral part of the production process. Avoiding costly repairs or overhauls due to destructive surge condition reduces downtime, saves equipment damage and ensures personnel are not exposed to harm. So, how can process engineers prevent catastrophic incidents to achieve an effective design for the control system?
Understanding the problem
Compressors are highly specialised pieces of equipment that are commonly custom designed, expensive to produce and costly to purchase. In refineries and petrochemical plants, they are used for different applications in the main and auxiliary process cycles. This could be a recycling compressor designed to provide a steady flow of process gas through a closed circuit to maintain the necessary process parameters in the plant units; feed compressors supplying process gas to the reactor; booster compressors or gas compressors managing fuel gas. They display an inherently transient behaviour and a small disturbance can quickly disrupt a compressor away from steady-state desired operating performance.
Surge occurs when the compressor outlet pressure is too high in relation to the flow through the compressor. If the compressor is not quickly controlled away from surge, the compressor can be damaged or even destroyed. An effective anti-surge control strategy is essential to protect the compressor. A proper surge control design is a mandatory design practice and seen as a measure of risk mitigation.
Process design has traditionally been executed using steady-state process simulators, albeit that today’s situation requires more capability and knowledge of the transient response of the process. Dynamic simulation used early in the design process can help to identify control issues more effectively and this results in better process design and smoother plant operations.
Compressors are subject to a variety of instabilities and upset conditions. Dynamic compressor models are a valuable tool in understanding upset and operational risk scenarios and have been made easier to adopt by integrating dynamic simulation closely within steady-state simulators. Using dynamic simulation, the process engineer can develop, evaluate and adjust control strategies for new and existing processes.
Dynamic modelling is a high value task requiring both expertise and experience. However, cutting-edge software makes the process simpler by automating dynamic modelling with a just few clicks to speed up model setup and enable more process engineers to perform compressor operability scenarios. All companies operating compressors, especially those processing gas in upstream and midstream will benefit from better reliability and reduced maintenance costs.
Improving compressor operability
Predicting process conditions that cause compressor to surge is a complex challenge. Understanding the process is fundamental to design an effective control strategy. The plant environment, for example, necessitates special considerations by the compressor designer to ensure a trouble-free operation after machine installation. The process control engineer must analyse all the variables, process dynamics and units interactions.
From the feasibility study, through to the front end engineering design (FEED) and detailed design, the engineer needs to consider many factors, including, compressor size, type, start-up, shutdown and much more. Process workflow and tighter time pressures to produce accurate, compliant, cost effective models for clients are other important considerations. Without the necessary tools and skills, companies suffer from inefficiencies in the overall design process.
Steady-state and dynamic models provide improved understanding of process dynamics and its interactions, which enable engineers to evaluate and adjust strategies before implementation. Using intuitive dynamic simulation software early in the design phase means the engineer can identify important operability and control issues quickly and more easily. Dynamic engineering software helps engineers to view the response of compressors to conditions that vary from steady-state. Robust and accurate dynamic modelling of compressor can prevent catastrophic equipment occurrences, such as compressor surge or flow reversal. The benefits of dynamic simulation help solve operational and design issues. Dynamic simulation is used as a validation tool, but also provides powerful insight into problem areas that would otherwise be overlooked.
Dynamic modelling has been made progressively easier to adopt by integrating dynamic simulation closely within steady-state simulators and introducing sample models to help engineers model their compressor installations without starting from the beginning.
Predicting success
AspenTech India's Sunil Patil
When produced correctly, the dynamic simulation models provide a vital resource for the operating company and manufacturer to protect the compressor and avoid hazards, such as exposure of process gas to the surrounding atmosphere. Greater understanding of dynamic plant behaviour will result in tremendous improvements in control and improved uptime.
For many production processes in the oil and gas, energy and chemicals industries, knowing the precise dynamic response of a compressor is extremely important to purge errors or reduce risk in the design or operating process. By adopting state-of-the-art dynamic simulation software, engineers can eliminate the risk of equipment failure with improved design workflow and optimised performance, which can contribute significantly to the safety and profitability of the operation.
____________________________________________________________________________________________________________________
The author is the Senior Principal Business Consultant (Engg) APAC at AspenTech, one of the world's leading suppliers of software that optimises process manufacturing