Supercritical fluid recycle for surge control of CO2 centrifugal compressors

AbstractThis paper presents computer-based design and analysis of control systems for centrifugal compressors when the operating fluid is supercritical CO2.It reports a non-linear dynamic model including a main forward compression line and two different configurations for the recycle antisurge line. Disturbance scenarios are proposed for testing the configurations and performance indicators are suggested to evaluate control performance and power consumption of the compression system.The paper demonstrates that compared to the hot recycle, the process configuration including a cold gas recycle has better overall stability, but higher power consumption and lower values for the control performance indicators. Based on the previous considerations, the paper gives suggestions regarding the choice of the recycle configuration. Moreover it compares subcritical and supercritical compression during surge prevention and highlights the importance of the selection of the gas recycle configuration when full recycle is needed

Centrifugal Pumps For Co2 Applications

LectureThere is a renewed interest in pumping CO2 in the liquid and supercritical states for many enhanced oil recovery (EOR), and new carbon capture and sequestration (CCS) projects. Referenced centrifugal technology currently available in the industry can cover discharge pressures up to 25 MPa (3600 psi). GE Oil & Gas has now developed and successfully tested pumps that are capable of providing solutions up to 60 MPa (8700 psi). This paper reports the activities performed for this development and the results of the tests

Application of Dynamic Centrifugal Compressor Model for Mechanical Vapor Recompression System Simulation

In order to reducing energy costs and CO2 foot-print, mechanical vapor recompression system (MVR) is used for thermal separation processes such as evaporation and distillation are energy intensive instead of multiple-effect evaporation system. For medium and high capacities, centrifugal compressor (fan) is the most commonly used type for gas compression with a limited operational range and control of the compressors is crucial for safe and efficient operation. The model based on first principles is developed for dynamic performance, which is determined from the compressor geometry and not from the experimentally determined characteristic performance curves. Impeller losses are studied: incidence, skin friction, choking, jet-wake mixing, blade loading, hub to shroud, tip clearance, shock and distortion losses. The vaneless diffuser outlet is calculated using a one-dimensional numerical solution to the underlying differential equations. Dynamic model of a centrifugal compressor capable of system simulation computational environment is presented. A model has been created for simulation of a separation and gas compression system. Based on the theory for centrifugal compressors and control theory a control strategy has been applied to the model based on the available equipment. The model has been used to investigate how the gas compression system responds to changes in the compressor inlet flows and conditions. The model has been used to investigate the performance of the gas compression system at off-design conditions. The surge line for the compressor can also be determined from the simulation results. Furthermore, the model presented here provides a valuable tool for evaluating the system performance as a function of various operating parameters

Tutorial on Centrifugal Compressor Surge Control

TutorialFor every centrifugal compressor installation, the design of the surge control system is vitally important to prevent damage of the compressor internal components, seals, and bearings. While most surge control systems are capable of preventing surge for steady-state operation, emergency shutdowns (ESDs) are particularly challenging, since the surge control system must respond faster than the deceleration rate of the train. This tutorial explores various aspects of compressor surge including steady state and transient operation

Turbomachinery for Refinery Applications

TutorialThis tutorial covers the basics, applications, and operation of compressors, expanders, steam turbines, and gas turbines in refinery applications. Modern refineries utilize a wide range of turbomachinery that must flexibly operate under harsh, fluid conditions with long life and minimal maintenance downtime. In refinery service, the fluids pose unique aerodynamic, materials, and structural design challenges including wet gas service, high gas path temperatures, and corrosive, flammable, and sometimes toxic service. These requirements make the design, packaging, controls, application, and operation of turbomachines in refineries highly complex and challenging. Operational and technical details of turbine and compression applications such as gas boost, refrigeration, hydrogen recycle, blow gas compression, coke gas compression, reformer recycle compression, steam turbine drivers, and gas turbine drivers will be discussed for refinery processes including alkylation, reforming, hydrocracking, fluid cracking, power generation, and gas boost. Topics cover refinery process fundamentals, turbomachines in refinery applications, design conditions, and -examples of special operational considerations in refinery service. A basic understanding of the processes as well as the type, power requirements, utilities, and application challenges of operating turbomachines in refineries is provided

TURBOMACHINERY FOR REFINERY APPLICATIONS

TutorialThis tutorial covers the basics, applications, and operation of compressors, expanders, steam turbines, and gas turbines in refinery applications. Modern refineries utilize a wide range of turbomachinery that must flexibly operate under harsh, fluid conditions with long life and minimal maintenance downtime. In refinery service, the fluids pose unique aerodynamic, materials, and structural design challenges including wet gas service, high gas path temperatures, and corrosive, flammable, and sometimes toxic service. These requirements make the design, packaging, controls, application, and operation of turbomachines in refineries highly complex and challenging. Operational and technical details of turbine and compression applications such as gas boost, refrigeration, hydrogen recycle, blow gas compression, coke gas compression, reformer recycle compression, steam turbine drivers, and gas turbine drivers will be discussed for refinery processes including alkylation, reforming, hydrocracking, fluid cracking, power generation, and gas boost. Topics cover refinery process fundamentals, turbomachines in refinery applications, design conditions, and -examples of special operational considerations in refinery service. A basic understanding of the processes as well as the type, power requirements, utilities, and application challenges of operating turbomachines in refineries is provided

Application and Design of Integrally Geared Compressors

TutorialTutorial 7: Integrally geared compressors (IGC’s) are common in plant/instrument air service as well as air separation applications, and continue to gain acceptance over a wide range of other applications. An IGC can achieve high efficiencies but is subject to complicated mechanical interactions. As a result of the mechanical complexity: design engineers, application engineers, and even end users of IGCs benefit from a diverse and in-depth knowledge of all of the engineering principles applied to arrive at an efficient machine with robust operating characteristics. This paper emphasizes the practical aspects of sizing and selection criteria for an integrally geared compressor for a range of applications and promotes a thorough understanding of practical limits of this type of compressor. Underlying aerodynamic principles are reinforced and limiting design aspects such as: gear tooth loading, lateral rotordynamics, bearing surface speed and loads, low- and highcycle fatigue of impeller blades are all iterated to find compromises to meet the demands of each application. Understanding the application and applying appropriate design limits is essential to meeting ever more challenging installation requirements

Site Performance Testing of Centrifugal Compressors and Gas Turbine Drivers

TutorialWhile factory performance tests for compressors and gas turbines are well defined in ASME power test codes, and can be performed under well controlled conditions, site performance tests must be performed under the conditions available at site. This requires methods to bring the compressor to valid operating conditions, as well as the capability to provide steady state operating conditions. Understanding compressor controls, available recycle and cooling capability, and the impact of the process requirements are crucial for successful tests. Limitations may come from the instrumentation that can be installed based on the site installation, and the impact of limited instrumentation is discussed. Compressor drivers also may impose limitations but also offer the capability for redundant measurements of certain parameters. Due to these constraints, the appropriate calculation of test uncertainties is vital, and the concepts of test uncertainty calculations is discussed and illustrated. This paper also provides insight into the necessary instrumentation and its calibration, the requirement for obtaining an accurate gas composition, and methods to obtain representative test points, as well as troubleshooting advice and methods to verify data

Tutorial on Centrifugal Compressor Surge Control

TutorialFor every centrifugal compressor installation, the design of the surge control system is vitally important to prevent damage of the compressor internal components, seals, and bearings. While most surge control systems are capable of preventing surge for steady-state operation, emergency shutdowns (ESDs) are particularly challenging, since the surge control system must respond faster than the deceleration rate of the train. This tutorial explores various aspects of compressor surge including steady state and transient operation