Recycle Dynamics During Centrifugal Compressor ESD, Start-Up and Surge Control

1996 ◽  
Author(s):  
K. K. Botros ◽  
B. J. Jones ◽  
D. J. Richards
Keyword(s):  
Centrifugal Compressor ◽  
Gas Flow ◽  
Check Valve ◽  
Control Flow ◽  
System Capacity ◽  
Laboratory Model ◽  
Closing Time ◽  
Start Up ◽  
Surge Control ◽  
Surge Protection

Recycle systems are important components in the operation of centrifugal compressor stations. They are essential during a start-up operation, for surge protection and for emergency shutdown (ESD). These operations are inherently dynamic where interactions between equipment, control and gas flow occur in a complex manner with the associated risk of compressor surge. Of particular importance are the effects of recycle system capacity, the recycle valve characteristics, check valve dynamic behavior, piping geometry and capacitance around the compressor unit, and the performance characteristics of the centrifugal compressor itself. This paper presents numerical results of the effects of some of these parameters on surge control, ESD and unit startup. These parameters are: i) The effects of damping the surge control flow signal in an attempt to suppress the signal noise, on the integrity of the surge control system, ii) The effects of recycle valve characteristics, stroke time and valve capacity on ESD, iii) The effects of recycle line size on ESD and iv) The effects of the recycle valve closing time (or rate) on the startup operation, with the intent of shortening this time to minimum for environmental reasons. Results were obtained from the solution of the pertinent dynamic equations describing the gas and equipment dynamics which has been verified against field and laboratory measurements. The examples presented in this paper were applied to a 24 MW natural gas compressor station on the NOVA Gas Transmission system, and to a scale-down laboratory model. Influence of other parameters from this investigation were published elsewhere and are cited in the reference section.

scholarly journals Centrifugal compressor anti-surge control system modelling

2022 ◽  
Vol 12 (2) ◽  
pp. 1419
Author(s):  
Nurlan Batayev ◽  
Batyrbek Suleimenov ◽  
Sagira Batayeva
Keyword(s):  
Control System ◽  
Natural Gas ◽  
Centrifugal Compressor ◽  
Block Diagram ◽  
System Modelling ◽  
Energy Balancing ◽  
Control Block ◽  
Gas Compression ◽  
Surge Control ◽  
Surge Protection

<span>From the middle of XX century, natural gas is an important mineral, widely used in the energy sector. Transportation of natural gas is carried out via gas pipeline networks and compression stations. One of the key features which need to be implemented for any centrifugal gas compressor is a surge protection. This article describes the method and develops software application intended for simulation and study of surge protection system of a centrifugal compressor used in modern gas compression stations. Within the article research method, modelling environment’s block diagram, proposed algorithms and results are described. For surge cases control and prediction, Anti-surge control block implemented which based on practical experience and centrifugal compressor theory. To avoid complicated energy balancing differential equations the volumetric flow calculation algorithm proposed which is used in combination with Redlich-Kwong equation of state. Developed software’s adequacy test performed through modeling of one-stage gas compression scheme at rated speed with comparison of parameters with reference commercial software and verification of the anti-surge control system.</span>

scholarly journals Improvements to a Centrifugal Compressor Surge Control System

1998 ◽  
Author(s):  
Blair J. Martin ◽  
James P. Patrick
Keyword(s):  
Control System ◽  
Centrifugal Compressor ◽  
Control Flow ◽  
Differential Pressure ◽  
Operating Conditions ◽  
Stable Operation ◽  
Time Model ◽  
Process Dynamics ◽  
Discharge Temperature ◽  
Surge Control

A surge control system for a natural gas centrifugal compressor station has been modified in order to reduce shutdowns caused by high discharge temperature and provide a more robust and stable operation. The process consists of a compressor driven by a 14 MW gas turbine and recycle piping, a 16” recycle valve, a PLC based surge control algorithm, a flow measurement element, and a compressor differential pressure transmitter. The control objective is to manipulate the recycle valve to maintain flow through the compressor to a setpoint determined from the differential pressure across the compressor. Field tests were conducted to measure the open loop process dynamics of the valve, piping, compressor and transmitters. From the test data, the relevant process dynamics were determined enabling the development of a first order plus dead time model of the system. The process dynamics are complex due to the gas dynamic effects of the station piping and tend to exhibit inverse and time delayed behavior. Large variations in process gain also create problems with obtaining a consistent flow response under different operating conditions. A stability analysis was completed and the control system was redesigned with several enhancements including derivative control, flow signal filtering, process linearization, and improved controller programming techniques. The results of the modifications are the compressor does not shut down when subjected to transients from other units, the compressor can be started against high head conditions, and the closed loop response time is ten times faster than the previous system. The new system has been in operation since May 1997.

Numerical Investigation of the Effect of Diffuser and Volute Design Parameters on the Performance of a Centrifugal Compressor Stage

2016 ◽  
Author(s):  
Lei Yu ◽  
William T. Cousins ◽  
Feng Shen ◽  
Georgi Kalitzin ◽  
Vishnu Sishtla ◽  
...  
Keyword(s):  
Centrifugal Compressor ◽  
Gas Flow ◽  
Pressure Rise ◽  
Design Parameters ◽  
Compressor Stage ◽  
Flow Distortion ◽  
Cross Sectional ◽  
Centrifugal Stage ◽  
And Performance ◽  
The Impact

In this effort, 3D CFD simulations are carried out for real gas flow in a refrigeration centrifugal compressor. Both commercial and the in-house CFD codes are used for steady and unsteady simulations, respectively. The impact on the compressor performance with various volute designs and diffuser modifications are investigated with steady simulations and the analysis is focused on both the diffuser and the volute loss, in addition to the flow distortion at impeller exit. The influence of the tongue, scroll diffusion ratio, diffuser length, and cross sectional area distribution is examined to determine the impact on size and performance. The comparisons of total pressure loss, static pressure recovery, through flow velocity, and the secondary flow patterns for different volute designs show that the performance of the centrifugal compressor depends upon how well the scroll portion of the volute collects the flow from the impeller and achieves the required pressure rise with minimum flow losses in the overall diffusion process. Finally, the best design is selected based on compressor stage pressure rise and peak efficiency improvement. An unsteady simulation of the full wheel compressor stage was carried out to further examine the interaction of impeller, diffuser and the volute. The unsteady flow interactions are shown to have a major impact on the performance of the centrifugal stage.

Flow With Shock Waves in a Transonic Centrifugal Compressor With a Low-Solidity Cascade Diffuser Using PIV

2004 ◽  
Author(s):  
Hiroshi Hayami ◽  
Masahiro Hojo ◽  
Norifumi Hirata ◽  
Shinichiro Aramaki
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Centrifugal Compressor ◽  
Gas Flow ◽  
Pressure Ratio ◽  
Transonic Centrifugal Compressor ◽  
Image Velocimetry ◽  
Rotor Stator Interaction ◽  
Rotating Impeller ◽  
Low Solidity Cascade Diffuser

A single-stage transonic centrifugal compressor with a pressure ratio greater than six was tested in a closed loop with HFC134a gas. Flow at the inducer of a rotating impeller as well as flow in a stationary low-solidity cascade diffuser was measured using a double-pulse and double-frame particle image velocimetry (PIV). Shock waves in both flows were clearly observed. The effect of flow rate on a 3D configuration of shock wave at the inducer and a so-called rotor-stator interaction between a rotating impeller and a stationary cascade were discussed based on a phase-averaged measurement technique. Furthermore, the unsteadiness of inducer shock wave and the flow in a cascade diffuser during surge were discussed based on instantaneous velocity vector maps.

scholarly journals Productivity Influence Factors of Tight Sandstone Gas Reservoir with Water Produced

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Yongchao Xue ◽  
Qingshuang Jin ◽  
Hua Tian
Keyword(s):  
Pressure Gradient ◽  
Relative Permeability ◽  
Gas Flow ◽  
Influence Factors ◽  
Stress Sensitivity ◽  
Consumption Pattern ◽  
Tight Sandstone ◽  
Gas Reservoir ◽  
Two Phase ◽  
Start Up

Finding ways to accelerate the effective development of tight sandstone gas reservoirs holds great strategic importance in regard to the improvement of consumption pattern of world energy. The pores and throats of the tight sandstone gas reservoir are small with abundant interstitial materials. Moreover, the mechanism of gas flow is highly complex. This paper is based on the research of a typical tight sandstone gas reservoir in Changqing Oilfield. A strong stress sensitivity in tight sandstone gas reservoir is indicated by the results, and it would be strengthened with the water production; at the same time, a rise to start-up pressure gradient would be given by the water producing process. With the increase in driving pressure gradient, the relative permeability of water also increases gradually, while that of gas decreases instead. Following these results, a model of gas-water two-phase flow has been built, keeping stress sensitivity, start-up pressure gradient, and the change of relative permeability in consideration. It is illustrated by the results of calculations that there is a reduction in the duration of plateau production period and the gas recovery factor during this period if the stress sensitivity and start-up pressure gradient are considered. In contrast to the start-up pressure gradient, stress sensitivity holds a greater influence on gas well productivity.

Dynamic Model of Multistage Centrifugal Compressor With a Stage-by-Stage Anti-Surge Recirculating System

2021 ◽  
Author(s):  
Nicola Casari ◽  
Michele Pinelli ◽  
Alessio Suman ◽  
Matteo Manganelli ◽  
Mirko Morini ◽  
...  
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Suction Side ◽  
System Level ◽  
Low Flow ◽  
Return Flow ◽  
Control Line ◽  
Compressor Surge ◽  
Surge Control ◽  
Surge Line

Abstract The operability region of a centrifugal compressor is bounded by the low-flow (or high-pressure ratio) limit, commonly referred to as surge. The exact location of the surge line on the map can vary depending on the operating condition and, as a result, a typical Surge Avoidance Line is established at 10% to 15% above the stated flow for the theoretical surge line. The current state of the art of centrifugal compressor surge control is to utilize a global recycle valve to return flow from the discharge side of a centrifugal compressor to the suction side to increase the flow through the compressor and, thus, avoid entering the surge region. This is conventionally handled by defining a compressor surge control line that conservatively assumes that all stages must be kept out of surge at all the time. In compressors with multiple stages, the amount of energy loss is disproportion-ally large since the energy that was added in each stage is lost during system level (or global) recycling. This work proposes an internal stage-wise recycling that provides a much more controlled flow recycling to affect only those stages that may be on the verge of surge. The amount of flow needed for such a scheme will be much smaller than highly conservative global recycling approach. Also, the flow does not leave the compressor casing and therefore does not cross the pressure boundary. Compared to global recycling this inherently has less loss depending upon application and specific of control design.

scholarly journals Transient Flow Characteristic of High-Pressure Hydrogen Gas in Check Valve during the Opening Process

Energies ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 4222
Author(s):  
Jianjun Ye ◽  
Zhenhua Zhao ◽  
Jinyang Zheng ◽  
Shehab Salem ◽  
Jiangcun Yu ◽  
...  
Keyword(s):  
High Pressure ◽  
Gas Flow ◽  
Transient Flow ◽  
Check Valve ◽  
Hydrogen Gas ◽  
Strong Impact ◽  
Hydrogen Flow ◽  
Hydrogen Systems ◽  
Pressure Hydrogen ◽  
Opening Process

In high-pressure hydrogen systems, the check valve is one of the most easy-to-damage components. Generally, the high-pressure hydrogen flow can generate a strong impact on the check valve, which can cause damage and failure. Therefore, it is useful to study the transient flow characteristics of the high-pressure hydrogen flow in check valves. Using dynamic mesh generation and the National Institute of Standards and Technology (NIST) real hydrogen gas model, a transient-flow model of the high-pressure hydrogen for the check valve is established. First, the flow properties of high-pressure hydrogen during the opening process is investigated, and velocity changes and pressure distribution of hydrogen gas flow are studied. In addition, the fluid force, acceleration, and velocity of the valve spool are analyzed quantitatively. Subsequently, the effect of the hydrogen inlet-pressure on the movement characteristic of the valve spool is investigated. The results of this study can improve both the design and applications of check valves in high-pressure hydrogen systems.

One-Sided Control of Surge in a Centrifugal Compressor System

2000 ◽  
Author(s):  
Frank Willems ◽  
Bram de Jager
Keyword(s):  
Centrifugal Compressor ◽  
Band Pass Filter ◽  
Pass Filter ◽  
System A ◽  
Operating Region ◽  
Stable Operating ◽  
Surge Control ◽  
Small Band ◽  
Band Pass ◽  
The One

Active surge control is studied in a centrifugal compressor system. To stabilize surge, a bleed valve is applied which is nominally closed and only opens to stabilize the system around the desired operating point. This bleed valve is controlled using a linear output feedback controller based on plenum pressure measurements. In this study, the practical limitations of this one-sided surge controller are examined. Experiments show that the performance of the controller is affected by measurement noise and the desired equilibrium point in the controller, which is not accurately known in the unstable operating region. Fully-developed surge is stabilized with relatively small stationary bleed valve mass flow using the proposed controller in combination with a small band-pass filter. Measurements are compared with the results of the Greitzer model. This model shows qualitative agreement with experiments. For the examined compressor system, a 3.5% extension of the stable operating region is obtained using the one-sided surge controller.

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