Design, Testing and Service
Leveraging the state of the art know-how and technological edge of its engineering staff, CST has developed a structured approach for designing compressors (aero-dynamic, mechanical and rotor-dynamic) based on complete compressor stage simulation and performance assessment. This approach results in an outstanding quality in compressor design and analysis (Root cause analysis & troubleshooting, Modifications and upgrades, Reverse engineering and modernization, Rehabilitation).
Design usually involves a preliminary definition of the compressor configuration and stage/s selection, followed by special analysis aimed to verify aero-dynamic performances and structural integrity of the selected compressor. These analysis, such as 3D Computational Fluid Dynamics (CFD), Finite Element Analysis (FEA) and rotor-dynamics (lateral and torsional analysis), are used also for in Field Support activities in order to investigate specific issues customers may face.
CST optimizes the compressor thermodynamic design, starting from standardized compression stages (integrally geared or between bearings compressor layout, 2D or 3D open or close impellers, vaneless or vaned diffusers, bladed return channels or volutes), to be adapted to customer requirements. Through this approach, we select the best stage configuration, matching the specific application and compressor performance curves, from choke to surge as a function of speed or IGV position.
Real gas equations of state are used to guarantee accurate performance curves.
TYPICAL TABLE OF STANDARD COMPRESSOR STAGES
TYPICAL CENTRIFUGAL COMPRESSOR PERFORMANCE CURVES
Once the machine configuration is selected, the aerodynamic design of rotating and stationary components is defined. All geometries (impellers, diffusers, volutes or return channels) are optimized to maximize efficiency and flow capability across the operating range.
AERO-DYNAMIC IMPELLER BLADE DESIGN
3D MODEL OF IMPELLERS AND SHAFT
3D CFD simulations are widely used by CST for:
IMPELLER BLADE STATIC PRESSURE DISTRIBUTION
DIFFUSER AND VOLUTE FLOWFIELD VISUALIZATION
The Finite element analysis (FEA) is typically performed by CST, here are some applications:
COMPRESSOR CASING DEFORMATION IN OPERATING CONDITIONS
TWO-DIAMETER MODE SHAPE OF AN OPEN IMPELLER
In addition to impeller modal analysis a rotodynamic study of rotating parts (pinion shaft of IGC, compressor shaft of between bearings ) is carried out by Lumped Parameter Models. This is according to API617 and API684 Standards, focusing on:
LUMPED PARAMETER SHAFT MODEL
LATERAL ANALYSIS OF AN IGC HIGH SPEED SHAFT
Variable Inlet Guided Vanes (known as IGVs) are commonly used to control the inlet mass flow of integrally geared compressors. IGV can lead to important energy savings with respect to a conventional inlet butterfly valve. This component strongly affects overall compressor performance and represents a critical component to design. CST has invested a significant effort to design IGVs for both levers and gear actuating system.
Process centrifugal compressors are designed by CST based on customer’s needs and requirements, in accordance with API617 Standards or API672 in case of packaged IGC for air.
CONTROL AND ANTI-SURGE
CST engineering services also include the philosophy of the control system, and the study and optimization of the best solution to prevent surging.
DRY GAS SEAL SYSTEM SELECTION AND SPECIFICATION
CST collaborates with the most reputed suppliers of dry gas seals with the aim to select the best solution for this very important component and its relevant system.
LUBRICATION SYSTEMS FOR ROTOR BEARINGS, GEARBOX AND MOTOR
CST can design customized systems based on specific requirement for the machine and customer needs.
CST service is not limited to the design and manufacturing of new units but covers also its customer for repairs instructions, parts reverse engineering and provision, modification, and optimization of existing compressors to meet new plant requirements, different gas condition and improve compressor performance.
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