Software for Selection & Sizing OF Valves

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Software for Selection & Sizing of Valves

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Software for Selection & Sizing OF Valves

  1. 1. Software for Selection & Sizing of Valves NIDHIN MANOHAR
  2. 2. • Introduction • Common types of valves • Control Valve selection and sizing Data collection Selection parameters Sizing Equations Cavitation / choking Noise calculations • Need for Software • Software in the Market
  3. 3. Common Valves types
  4. 4. Discharge control Valves (cone or Needle) • Recommended Uses:    for applications where discharge is to be maintained  constant • Sizes : max. 1800mm Air Inlet valves (Anti Vacuum valves) • Are  provided  on  pressure  steel  mains  as  a  safety  measure  against  total  collapse  due  to  formation  of  vacuum  inside  the  pipe  on  account  of  changed  conditions  of  flow  caused  by  sudden  closure  of  valve  or tripping of pumps. • Are  fixed  on  horizontal  stretches  of  pipeline  immediately downstream of the line valve.
  5. 5. Air Valves • Are used to release and introduce air into the pipeline  during filling and de-watering of the pipeline. Pressure Relief Valves • Are used when the pressure in the pipeline exceeds a  pre-set value. Zero velocity Valves • Are used to arrest the forward moving water column at  zero  momentum  before  any  return  velocity  is  established. Scour Valves • Are  sluice  valves  located  at  the  lowest  point  in  the  section  used  for  emptying  /de-watering  an  isolated  main.
  6. 6. Other Valve Types
  7. 7. SELECTION PARAMETERS Appropriate valve selection is based on the complete knowledge of the service characteristics. •Fluid Type and characteristics The fluid being handled (liquid / gas / two phase/ steam/ slurry/ solid) and its characteristics like clean / dirty / containing large suspended solids / liable to solidification / viscous / corrosive / flammable / fouling / scaling etc. •Pressure, temperature limitations, and chemical resistance Valves are normally allocated a rating according to the maximum operating pressure and temperature, which is compatible with the rating of the connected piping system of flanges. The operating temperature limits the materials which may be used in the valve construction, particularly for trims, seals, linings or lubricants. Materials may also be limited by the pressure, fluid concentration, and condition. ANSI Pressure Nominal Class pounds of Pressure (PN) force per square allowable inch of surface area pressure in bar 150 300 600 900 1500 2500 4500 16 40 100 160 250 400 700
  8. 8. •Operation and Maintenance Requirements Consideration should be given to -Fire resistance -Ease and Speed of Operation -Leak tightness -Maintainability -Weight and Dimensions (construction, handling, etc) -Storage and Commissioning -Location (eg: sea bed valves) -Line cleaning Requirements ( eg. Ability to pass; cleaning pigs)
  9. 9. Selection parameters •Required flow characteristic –relationship between flow through the valve and its travel
  10. 10. Rangeability The rangeability of a valve is defined as the ratio of maximum and minimum controllable flow. Usually for almost 90% of requirements, a rangeability of 30:1 in valve is enough to control minimum and maximum flow requirements. The rangeability above 30% will also be available depending upon the requirement. However, rangeability above 100:1 is seldom used. Higher rangeability of above 100:1 will call from total design change in the valve including provision of excess stroke and high thrust actuators to valves.
  11. 11. Selection Example Application - Fluid : clean water - Temperature : 35 deg C - Pressure : 3 bar Rating - Size : DN 250 - Flow resistance : low - Seat tightness : Medium From Table A1, consider the following Flow resistance, Type of fluid, fluid condition, pressure, temperature, size, leak tightness(Table A5). Check for desired features (Table A3) and materials (Table A4)
  12. 12. Sizing Equations and Flowchart for Incompressible and Compressible Flows
  13. 13. Remarks Equations Piping Geometry Factor Value of N U.S ΣK (Cd ) 2 = 1]½ N2 For FLP see “Liquid Fp = [ Choked Flow” Sum of velocity head Coefficient ΣK K1 1 K2 1 KB 1 KB 2 Resistance coefficient For abrupt transitions d K 2 = 10[1 − ( )] 2 D Inlet fitting coefficient Liquid Gas Vapor Steam 0.00214 d K B1= K B 2 = 1( ) 4 D d K 1= 0.5[1 − ( ) 2 ] 2 D Bernoulli Coefficient For FLP and XTP Line Velocity 890 Sl Ki =K1 + KB1 Feet/Second Meter/Second Range (Ft/sec.) q q U = 354 2 2 2.245D D qT qT U= U = 124 695 pD 2 pD 2 w W U = 354 U= 2 λD 2 19.6γD 23w W U= U = 685 2 pD pD 2 U= 5-10 Norm. 40-50 Max. 250-400 70 wet 300 superheated Acoustic Velocity (Mach 1.0) kT M Ua = 49 T kT M U a= 20 T U a= 24.5 T Ua = 500 <0.15 Mach Steam, Dry Saturated U a= 60 T U a= 1650 Vapor U a= 608.1 kpv Ua = 1038 kpv <0.10 Mach Gas Air Steam, superheated U a= 223 U a= 91 <0.3 Mach
  14. 14. Remarks Equation Value of N Sl U.S Gas vapor – (All Equations: x<FkxT wg = N 6 FpCvY xp 1 y 1 63.3 qg = N 7 FpCvp1Y Variations for selected units x GgT 1Z 1360 wg = N 8FpCvp1Y xM T 1Z 2.73 19.3 qg = N 9 FpCvp1Y x MT 1Z 4.17 0.948 7320 22.4 x 3FkxT Expansion factor Y =1 Lower limit = 0.667 Sp. Ht. Ratio factor Fk = k/1.40 Mfr’s factors xT = C12 = 0.8C f 16000 XT with reducers x TP = xT xT Ki [ (C d ) 2 + 1] −1 Fp 2 N 5 2 1000 0.0024 1.0 0.152 2.0 0.304 Ki = (See piping geometry factor) Steam Dry and (Saturated) For x<xTP For x>xTP (Choked flow) w = NFpCvp1(3 − x )( x ) x TP w = NFpCvp 1 xTP
  15. 15. Remarks Equations qf = N1FpCv Value of NI U.S ∆p Gf Value of N Sl 0.08665 Turbulent and Non-cavitating ∆p Mf = N 6 FpCv 2.73 qf = N1FLPCv 0.8065 Mf = N 6 FlpCv Choked p1 − pvc Gf p1 − pvc Gf 2.73 Pvc = FfPv FF = 0.9-0.28 FLP = [ pv pc 1 Ki + (Cd ) 2 ]− ½ 2 N2 FL 0.00214 Ki = (See piping Geometry factor) qf = N10 ∆p ( FsFpCv) − 3 / 2 µ FpFd 2 1 / 3 ( FLPCv ) 2 ) [ = 1]1 / 6 FLP N2D4 Laminar Fs = ( Transitional qf = N 1FR F p Cv ∆p Gf 173 0.00214 0.0865
  16. 16. Sizing Example: Given : Q = 500gpm, Gf = 0.9, differential pressure = 20 psi, Dynamic Viscosity = 20000 cp. Selected valve is butterfly with Cv/d 2 =19, Fs = 0.93 For Turbulent flow, qf = N 1 FpCv 500 = 1 (1)Cvt ∆p N 1 = 10 . Gf 20 0.9 => Cvt = 106 For Laminar flow, ∆p qf = N10 (FsFpCv )3 / 2 µ 2 3 N =52 10 1  500(20000)  Cvs = 0.93  52(20)  = 520  
  17. 17. Z= Cvt 106 = = 0.21 Cvs 520 This value of Z is less than the 0.46 limit and so the flow is laminar. The Cv required is 520. Cv = 520 = 19 d2 Cv 520 d= = = 5.23 ≈ 6 inch 19 19 If Z is between 0.46 and 20, flow is transitional and if it is more than 20, flow is turbulent. In case of transitional flows, Cv = Cvt / FR Where  Cvs  FR = 1.044 − 0.358  C    vt  0.655
  18. 18. Requirement for Valve Selection and Sizing Software Plant and valve designers need time to optimize control quality, the sound level and power consumption as well as to handle increasing regulation paperwork and economic aspects. Sizing control valves from a total point of view is a challenge for the project engineer as well as for the valve manufacturer's specialists, even if they use modern powerful in-house sizing programs and tools. In comparison to the past, the time available for major projects has been more than halved, the specification volume -including the increasing paperwork associated with standards, special regulations and tailored customer requirements have more than doubled.
  19. 19. Negative effects of today are: valve specification sheets are often of low quality, operating points are missing or not logically sorted to qmax, qnorm, qmin, Important property data (like the vapour pressure) may be missing, no information about the worst-case conditions like during start-up, no control loop information etc. No wonder that sources of competence for high-level engineering for valves with higher demands have dried out and the risk of “quick and dirty” sizing is increasing. Some of the Valve selection and Sizing software available today looks at plant parameters (pipework, pipe devices, flow meters and valves) from an overall point of view with expert system features to compensate for the negative trends described above
  20. 20. Software are helpful in Identifying Planning errors and simulating real life scenarios thereby helping in optimization of the required Valve. Some cases are 1. Energy Saving by Plant and Valve Optimization 2. Noise Treatment Planning 3. Fluid Property Substitution in Sizing Equations
  21. 21. Software available in the market include 1. Autovalv - FCRI 2. CONVAL - F.I.R.S.T Germany 3. Quicksize - Dresser Masoneilan 4. FirstView - Fischer Rosemount 5. Engineers Aide - Gulf Publishing Software Co. 6. CvSpec
  22. 22. AUTOVALV A software for control valve selection and sizing
  23. 23. The CONVAL® software treats the plant and valve sizing parameters from an overall point of view, issuing dynamic graphics with installed characteristics concerning flow, power, gain and outlet velocity as a function of the valve coefficient cv value and the valve travel. The software is a manufacturer independent optimization tool for pipelines and pipe devices, including material and property database for more than 1,000 substances including hydrocarbons. Ethylene, propylene, chlorine, natural gas AGA 8 and sixty other industrial fluids are calculated very accurately using equations of state developed by the Ruhr University of Bochum
  24. 24. Hints The following data may also be of help in getting a better performance from a valve. The Line velocity may be in the range given below Liquid 5-10 ft/sec normally 40-50 ft/sec maximum Gas 250 - 400 ft/sec typical < Mach 0.3 Steam or Vapour 70-100 ft/sec 0-25 psig 100-170 ft/sec dry, saturated > 25psig <Mach 0.1 115-330 ft/sec superheated > 200 psig <Mach 0.15
  25. 25. THANKYOU

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