Selection Criteria of Spring Stiffness for Nozzle Type Check Valves in Compressor Station Applications

2011 ◽  
Author(s):  
K. K. Botros
Keyword(s):  
Selection Criteria ◽  
Hydrodynamic Force ◽  
Pressure Ratio ◽  
Check Valve ◽  
Compressor Station ◽  
Force Coefficient ◽  
Minimum Flow ◽  
Open Position ◽  
Type Check ◽  
Nozzle Type

Nozzle type check valves are often employed in compressor stations in three locations: compressor outlet, station discharge and station by-pass. The fundamental design concept of these valves is based on creating a converging diverging flow through the valve internal geometry such that a minimum area is achieved at a location corresponding to the back of the check valve disc at fully open position. This will ensure maximum hydrodynamic force coefficient which allows the valve to be fully open with minimum flow. Spring forces and stiffness determine the performance of this type of check valves and impact the overall operation and integrity of compressor station. This paper examines the effects of various spring characteristics and stiffness in relation to the compressor and station flow characteristics. The results show that when the spring forces are higher than the maximum hydrodynamic force at minimum flow, the disc will not be at fully open position, which will give rise to disc fluttering and potential for cyclic high velocity impact between components of the internal valve assembly. This could lead to self destruction of the check valve and subsequent risk of damage to the compressor unit itself. The paper also points to the fact that the spring selection criteria for a unit check valve are different than that for station and bypass check valves. An example of a case study with actual field data from a high pressure ratio compressor station employing this type of check valves is presented to illustrate the associated dynamic phenomena and fluid-structure interaction within the internal assembly of the check valve.

Spring Stiffness Selection Criteria for Nozzle Check Valves Employed in Compressor Stations

2011 ◽  
Vol 133 (12) ◽  
Author(s):  
K. K. Botros
Keyword(s):  
Selection Criteria ◽  
Hydrodynamic Force ◽  
Pressure Ratio ◽  
Flow Characteristics ◽  
Check Valve ◽  
Compressor Station ◽  
Force Coefficient ◽  
Minimum Flow ◽  
High Pressure Ratio ◽  
Open Position

Nozzle type check valves are often employed in compressor stations in three locations: compressor outlet, station discharge, and station bypass. The fundamental design concept of these valves is based on creating a converging diverging flow through the valve internal geometry such that a minimum area is achieved at a location corresponding to the back of the check valve disk at the fully open position. This will ensure maximum hydrodynamic force coefficient which allows the valve to be fully open with minimum flow. Spring forces and stiffness determine the performance of this type of check valves and impact the overall operation and integrity of the compressor station. This paper examines the effects of various spring characteristics and stiffness in relation to the compressor and station flow characteristics. The results show that when the spring forces are higher than the maximum hydrodynamic force at minimum flow, the disk will not be at the fully open position, which will give rise to disk fluttering and potential for cyclic high velocity impact between components of the internal valve assembly. This could lead to self destruction of the check valve and subsequent risk of damage to the compressor unit itself. The paper also points to the fact that the spring selection criteria for a unit check valve are different than that for station and bypass check valves. An example of a case study with actual field data from a high pressure ratio compressor station employing this type of check valves is presented to illustrate the associated dynamic phenomena and fluid-structure interaction within the internal assembly of the check valve.

Full-Scale Reynolds Number VIV Testing of Tri-Helically Grooved Drill Riser Buoyancy Module

2018 ◽  
Author(s):  
Collin Gaskill ◽  
Jie Wu ◽  
Decao Yin
Keyword(s):  
Reynolds Number ◽  
Large Scale ◽  
Hydrodynamic Force ◽  
Oscillation Amplitude ◽  
Cross Flow ◽  
Hydrodynamic Performance ◽  
Test Model ◽  
Force Coefficient ◽  
Test Cylinder ◽  
Test Models

A newly developed Tri-Helically Grooved drilling riser buoyancy module design was tested in the towing tank of SINTEF Ocean in June 2017. This new design aims to reduce riser drag loading and suppress vortex-induced vibrations (VIV). Objectives of the test program were two-fold: to assess the hydrodynamic performance of the design allowing for validation of previous computational fluid dynamics (CFD) studies through empirical measurements, and, to develop a hydrodynamic force coefficient database to be used in numerical simulations to evaluate drilling riser deformation due to drag loading and fatigue lives when subjected to VIV. This paper provides the parameters of the testing program and a discussion of the results from the various testing configurations assessed. Tests were performed using large scale, rigid cylinder test models at Reynolds numbers in the super-critical flow regime, defined as starting at a Reynolds number of Re = 3.5 × 105 – 5.0 × 105 (depending on various literatures) and continuing until Re = 3 × 106. Towing tests, with fixed and freely oscillating test models, were completed with both a bare test cylinder and a test cylinder with the Tri-Helical Groove design. Additional forced motion tests were performed on the helically grooved model to calculate lift and added mass coefficients at various amplitudes and frequencies of oscillation for the generation of a hydrodynamic force coefficient database for VIV prediction software. Significant differences were observed in the hydrodynamic performance of the bare and helically grooved test models considering both in-line (IL) drag and cross-flow (CF) cylinder excitation and oscillation amplitude. For the helically grooved model, measured static drag shows a strong independence from Reynolds number and elimination of the drag crisis region with an average drag coefficient of 0.63. Effective elimination of VIV and subsequent drag amplification was observed at relatively higher reduced velocities, where the bare test model shows a significant dynamic response. A small level of expected response for the helically grooved model was seen across the lower range of reduced velocities. However, disruption of vortex correlation still occurs in this range and non-sinusoidal and highly amplitude-modulated responses were observed.

Single Versus Dual Recycle System Dynamics of High Pressure Ratio, Low Inertia Centrifugal Compressor Stations

2011 ◽  
Vol 133 (12) ◽  
Author(s):  
K. K. Botros
Keyword(s):  
High Pressure ◽  
Centrifugal Compressor ◽  
Dynamic Instability ◽  
Pressure Ratio ◽  
Check Valve ◽  
Analytical Methodology ◽  
High Pressure Ratio ◽  
Compressor Surge ◽  
Rapid Transients ◽  
Single Versus

Compression systems are designed and operated in a manner to eliminate or minimize the potential for surge, which is a dynamic instability that is very detrimental to the integrity of the compressor unit. Compressor surge can occur when compressors are subjected to rapid transients such as those occurring following an emergency shutdown (ESD) or a power failure, which in turn, requires fast reaction. To prevent this from occurring, compressor stations are designed with single or dual recycle systems with recycle valves, which are required to open upon ESD. There has been extensive debate and confusion as to whether a single recycle or a dual recycle system is required and the circumstances and the conditions under which one system or the other must be used. This paper discusses this crucial design issue in detail and highlights the parameters affecting the decision to employ either system, particularly for high pressure ratio, low inertia compressors. Parameters such as gas volume capacitance (V) in the recycle path, compressor power train inertia, compressor performance characteristics, the recycle valve coefficient (Cv), prestroke and stroke time, and check valve dynamic characteristic are crucial in determining the conditions for dynamic instabilities. A simple analytical methodology based on the perturbation theory is developed that provides a first-cut analysis to determine if a single recycle system is adequate for a given compression system. The concept of an inertia number is then introduced with a threshold value that determines which recycle system to use. Techniques to circumvent compressor surge following ESD are discussed and their respective effectiveness are highlighted including when and if a delay in the fuel cutoff will be effective. An example of a case study with actual field data of a high pressure ratio centrifugal compressor employed in a natural gas compressor station is presented to illustrate the fundamental concept of single versus dual recycle systems.

Design and Fabrication of the Piezoelectrically Actuated Micropump with Implanted Check Valves

2013 ◽  
Vol 284-287 ◽  
pp. 2032-2036
Author(s):  
Chiang Ho Cheng ◽  
Yi Pin Tseng
Keyword(s):  
Stainless Steel ◽  
Flow Rate ◽  
Steel Substrate ◽  
Check Valve ◽  
Maximum Flow ◽  
Mems Fabrication ◽  
Sinusoidal Waveform ◽  
Nickel Electroforming ◽  
Bridge Type ◽  
Type Check

This paper aims to present the design, fabrication and test of a novel piezoelectrically actuated, check valve embedded micropump having the advantages of miniature size, light weight and low power consumption. The micropump consists of a piezoelectric actuator, a stainless steel chamber layer with membrane, two stainless steel channel layers with two valve seats, and a nickel check valve layer with two bridge-type check valves. The check valve layer was fabricated by nickel electroforming process on a stainless steel substrate. The chamber and the channel layer were made of the stainless steel manufactured using the lithography and etching process based on MEMS fabrication technology. The effects of check valve thickness, operating frequency and back pressure on the flow rate of the micropump are investigated. The micropump with check valve 20 μm in thickness obtained higher output values under the sinusoidal waveform of 120 Vpp and 160 Hz. The maximum flow rate and backpressure are 1.82 ml/min and 32 kPa, respectively.

Research on Open and Close Characteristics of Passive Shuttle-Type Anti-Water-Attack Check Valve

2011 ◽  
Vol 474-476 ◽  
pp. 2290-2295
Author(s):  
Bei Ping Xiang ◽  
Guo Fu Yin ◽  
Xiang Wei Zeng ◽  
Hong Bin Zang
Keyword(s):  
Flow Field ◽  
Rapid Change ◽  
Check Valve ◽  
Pressure Change ◽  
Pipeline System ◽  
Hydraulic Damper ◽  
Pressure Pipeline ◽  
Set Up ◽  
Opening And Closing ◽  
Type Check

Water-attack is very harmful to pressure pipeline system security. Passive shuttle-type anti-water-attack check valve can adjust its open and close time by hydraulic damper, and cushion the rapid change of liquid momentum in order to protect the pumps and pipelines. The structure and working principle of this passive check valve are introduced, and the dynamics model is set up. The opening and closing characteristics of the model is analyzed, and simulation comparison is done between the flow field and pressure change laws of shuttle-type check valve and those of swing check valve. The simulation result shows that the hydraulic damper works very well, the flow field of passive shuttle-type check valve is symmetrical, the forces acting on the shuttle is balanceable, and shuttle-type check valves can replace swing check valves in many fields.

Single vs. Dual Recycle System Requirements in the Design of High Pressure Ratio, Low Inertia Centrifugal Compressor Stations

2011 ◽  
Author(s):  
K. K. Botros
Keyword(s):  
High Pressure ◽  
Centrifugal Compressor ◽  
Dynamic Instability ◽  
Pressure Ratio ◽  
Check Valve ◽  
Threshold Value ◽  
Analytical Methodology ◽  
High Pressure Ratio ◽  
Compressor Surge ◽  
Rapid Transients

Compression systems are designed and operated in a manner to eliminate or minimize the potential for surge, which is a dynamic instability that is very detrimental to the integrity of the compressor unit. Compressor surge can occur when compressors are subjected to rapid transients such as those occurring following an emergency shutdown (ESD) or a power failure, which in turn, requires fast reaction. To prevent this from occurring, compressor stations are designed with single or dual recycle systems with recycle valves, which are required to open upon ESD. There has been extensive debate and confusion as to whether a single recycle or a dual recycle system is required and the circumstances and the conditions under which one system or the other must be used. This paper discusses this crucial design issue in detail and highlights the parameters affecting the decision to employ either system, particularly for high pressure ratio, low inertia compressors. Parameters such as gas volume capacitance (V) in the recycle path, compressor power train inertia, compressor performance characteristics, the recycle valve coefficient (Cv), pre-stroke and stroke time, and check valve dynamic characteristic are crucial in determining the conditions for dynamic instabilities. A simple analytical methodology based on the perturbation theory is developed that provides a first-cut analysis to determine if a single recycle system is adequate for a given compression system. The concept of an inertia number is then introduced with a threshold value that determines which recycle system to use. Techniques to circumvent compressor surge following ESD are discussed and their respective effectiveness are highlighted including when and if a delay in the fuel cut-off will be effective. An example of a Case study with actual field data of a high pressure ratio centrifugal compressor employed in a natural gas compressor station is presented to illustrate the fundamental concept of single vs. dual recycle systems.

Passive Control Shuttle-Type Check Valve – a New Nuclear-Class Fluid Control Component

2011 ◽  
Vol 317-319 ◽  
pp. 1474-1477
Author(s):  
Kun Chen ◽  
Xiang Wei Zeng ◽  
Xiao Ping Qiu ◽  
Xiao Ge Zeng
Keyword(s):  
Flow Resistance ◽  
Passive Control ◽  
Simulation Analysis ◽  
Check Valve ◽  
Resistance Coefficient ◽  
Structural Principle ◽  
Symmetric Structure ◽  
Stop Time ◽  
Fluid Control ◽  
Type Check

A novel check valve - passive control shuttle-type check valve is introduced in this paper based on the comparison of the existing swing check valves including the liquid, structural principle, flow resistance coefficient, airproof and start-stop performances. The experimental and simulation analysis validated that shuttle-type check valve has the advantages of symmetric structure along the pipeline axis, balance circle flow, low coefficient streamline, adjustable start-stop time, multi-airproof, zero leakage and less noise.

scholarly journals A Semi-Analytical Method for Calculating the Hydrodynamic Force on Perforated Plates in Oscillating Flow

2019 ◽  
Author(s):  
Fredrik Mentzoni ◽  
Trygve Kristiansen
Keyword(s):  
Analytical Method ◽  
Hydrodynamic Force ◽  
Added Mass ◽  
Navier Stokes ◽  
Oscillating Flow ◽  
Force Model ◽  
Hydrodynamic Coefficients ◽  
Two Dimensional ◽  
Force Coefficient ◽  
Perforated Plates

Abstract A two-dimensional numerical analysis on the hydrodynamic force of perforated plates in oscillating flow is presented, and a new semi-analytical force model is proposed. Plates with ten different perforation ratios, τ, from 0.05 to 0.50 are simulated. The Keulegan–Carpenter numbers in the simulations cover a range from 0.002 to 2.2 when made nondimensional with the width of the plates. Resulting hydrodynamic added mass and damping coefficients are presented. All perforated plates with perforation ratios greater than or equal to 10% are found to be damping dominant. The numerical results are obtained using a two-dimensional Navier–Stokes solver (CFD), previously validated against dedicated 2D experiments on perforated plates. Furthermore, we present verification of the code against the analytical solid flat plate results by Graham. The presently obtained hydrodynamic coefficients are compared with the state-of-the-art semi-analytical method for force coefficient calculation of perforated plates by Molin, as well as the recommended practice for estimating hydrodynamic coefficients of perforated structures by DNV GL. Based on the CFD results, a new method for calculating the hydrodynamic force on perforated plates in oscillating flow is presented. The method is based on curve fitting the present CFD results for perforated plates, to the analytical expressions obtained for solid plates by Graham. In addition to its simplicity, a strength of the method is that coefficients for both the added mass and damping are obtained.

scholarly journals 064 Sugars in Tropical-type Sweetpotato

HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 399D-399
Author(s):  
Tania Hernández-Carrión ◽  
Carlos E. Ortiz ◽  
Rafael Montalvo-Zapata ◽  
Milca I. Mercado-Olivieri ◽  
Luis E. Rivera
Keyword(s):  
Refractive Index ◽  
Puerto Rico ◽  
Genetic Improvement ◽  
Selection Criteria ◽  
Sugar Content ◽  
General Description ◽  
The Caribbean ◽  
Processed Products ◽  
Refractive Index Detector ◽  
Type Check

Tropical-type is a general description for sweetpotato cultivars with intermediate sweetness that have light-fleshed roots. This type is commonly grown and consumed across the Caribbean Basin. Systematic efforts for the genetic improvement of the tropical-type sweetpotato have been limited. Cultivars available for being grown in Puerto Rico lack either the sweetness or attractiveness demanded by producers and consumers. Defining optimum sweetness in this type is important because this characteristic is totally dependent on the root's sugar content and cannot be modified as in processed products. The objective was to obtain data on sugar content for the development of quantitative selection criteria for sweetness. Raw, boiled and baked roots were evaluated for glucose, sucrose, fructose, and maltose. `Mina' and `Miguela', tropical-type cultivars widely accepted for sweetness and table quality but poor yielders were used. `Viola', a substaple type, was the check. Sugars were detected by HPLC. Sugar-Pak (Waters) and LC-NH2 (Phenomenex) columns and a refractive index detector were used for the analyses. Across cultivars and type, sucrose (4.0% to 6.5%) was more concentrated than glucose (0.4% to 0.8%) and fructose (0.3% to 0.4%). Concentration of sucrose in the tropical type (7.7%) was higher than in the substaple type check (4.4%). Boiling or baking did not markedly change the concentration of the above sugars. Maltose was not detected in raw samples; however, both boiling and baking increased maltose concentration from 9.0% to 15.4%. In the development of a practical quantitative selection criteria for sweetness, both sucrose and maltose must be considered.

Sign in / Sign up

Export Citation Format

Share Document