Development of Compression System Dynamic Simulation Code for Testing and Designing of Anti-Surge Control System

Abstract

As cost of damages to the compression systems in oil and gas industry can lead to significant capital cost loss and plant downtime, these valuable assets must be carefully protected to achieve a high level of production and operational reliability. In recent years, several research activities have been conducted to develop knowledge in analysis, design and optimization of compressor anti surge control system. Since, the anti-surge control testing on a full scale compressor are limited for possible consequences of failure and also the experimental facility can be expensive to set up control strategies and logics, design process often involves analyses using compression system dynamic simulation. Such Simulator enables the designer to test the new control logic and see the results before implementing it on governor system. This would increase the reliability and prevents undesirable costs resulting from practical trial and error process. Taking into account its own requirements and market demand, a high fidelity compression system dynamic simulation environment has developed by MAPNA Turbine (TUGA) to verify the anti-surge control system design and test the control logic across the all operating range of the compressor performance. Typical control scenarios that have to be considered are process control, starting and stopping, and emergency shutdowns. Having such simulator is also deemed to be essential to serve other applications during all stages of system life cycle, including but not limited to the educational tool for operators training, Site Acceptance Test (SAT) and Factory Acceptance Test (FAT) and compression plant design optimization. This research focuses on developing and validating a physics-based, modular, non-linear and one-dimensional dynamic model of a compression system: centrifugal compressor and its surrounding process equipment like scrubber, cooler, a recycle line with a control valve and check valve. The mathematical approach of the model is based on laws of conservation and the included ordinary differential equations (ODEs) which describe the system dynamics, is solved by using advanced computational method in an in-house FORTRAN code. Compressor characteristics maps generated from company compressor test bench are used to determine compressor pressure ratio and efficiency. All equipment and inlet/outlet accessories as well as test instructions follow the requirements of PTC10. The simulation within a wide range of operating conditions allows a parametric study to be performed and the optimal values of the control parameters to be selected. In order to check the validity of the model, the simulation results are then compared with experimental data taken on the company industrial compressor test facility and also with operational field measurement.