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KONTROLL VENTILER. JAN O HJETLAND. Fag disipliner. Prosess Material Instrument ”Piping” Maling Innkjøp Produksjons oppfølging. Hvilken type kontroll ventiler har vi. Sete ventil (Globe) Kule ventil (Bal) Sving ventil (Butterfly). Hva er en kontroll ventil.
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KONTROLL VENTILER • JAN O HJETLAND
Fag disipliner • Prosess • Material • Instrument • ”Piping” • Maling • Innkjøp • Produksjons oppfølging
Hvilken type kontroll ventiler har vi Sete ventil (Globe) Kule ventil (Bal) Sving ventil (Butterfly)
Hva er en kontroll ventil En kontroll ventil er arbeideren i en prosess lup
LC LC Separator Level Control Gas outlet Crude Inlet from well head Gas Oil Oil Water Oil level Control valve Water level Control valve
1) Beregning av ventilstørrelse 2) Beregning av støy / andre forhold 3) Valg av ventiltype - gjenta fra 1 4) Valg av materialer / pakkboks 5) Beregning og valg av aktuator 6) Tilleggsutstyr / endelig beskrivelse Ventildimensjonering og valg - fremgangsmåte Gjenta beregningene med relevante ventildata
6) Tilleggsutstyr / endelig beskrivelse 5) Beregning og valg av aktuator 2) Beregning av støy / andre forhold 3) Valg av ventiltype - gjenta fra 1 4) Valg av materialer / pakkboks 1) Beregning av ventilstørrelse Beregne ventilstørrelse - bakgrunn • Har stort sett vært basert på leverandørenes egne standarder / metoder • Standardiseringsarbeide har pågått siden tidlig 1960 • ISA etablerte en komite i 1967 som skulle utvikle og distribuere standard ligningssett - ble til en “American National Standard” • IEC benyttet ISAarbeidet som basis for å formulere internasjonale standarder • ISA og IEC standardene er harmonisert, med noen få unntak (nomenklatur) • ANSI / ISA Standard betegnes S75.01 • IEC standard har betegnelsen 534-2-1 og 534-2-2 (inkompressible og kompressible medier) Disse standardene inneholder også metodikk for støyberegninger
Støy i reguleringsventiler • Støy i reguleringsventiler er en stor bidragsyter til anleggets totale bakgrunnsstøy • Myndighets krav blir stadig strengere • Støykilder i et anlegg er vanskelige å identifisere, p.g.a. mange forskjellige kilder, refleksjoner, forplantning av støy etc. • Brukere som ser bort fra støykravene er eksponert for unødvendige belastninger • Kontraktører som garanterer å møte spesifikasjoner for støy er eksponert for potensielle erstatningssaker / kostnader ved korreksjoner
R 1 + r R + r LpA = F + 10 Log Linje-kilde Tverrsnitt av rør For hver dobling av avstand, tapes 3 dBa
Noise Trims - Whisper I • Splits flow into small rectangular passages • Increases Peak Frequency • Complimentary body design • Most effective dP/P1 <0.6 • Up to 20 dB attenuation
Whisper III • Flow passes through small holes • Level 3 Uses 1.6 mm dia • Level 1 Uses 3.2 mm dia • 6 dBA difference • Increases frequency • Complimentary body design • Jet independence • Up to 30 dB attenuation
C3 B3 1.6 mm 1.6 mm 1.6 mm A3 Whisper III C/d = 3.4 dP/P1< 0.99 C/d = 2.7 dP/P1 < 0.75 P2 P1 C/d = 2.0 dP/P1 < 0.6 Air Flow
WhisperFlo • Staged Reduction of Pressure • Shift Frequency Spectrum Higher • Unique Passage Shape • Jet Independence • Manages Velocity Using an Expanding Area Principle • Complimentary Body Design • Up to 40 dB attenuation
WhisperFlo Flow Passage Outlet Inlet
Begrense støy-generering • Globe ventil med diffuser
VESKE • FLASING • CAVITATION
Liquid Flow through an Orifice Vena Contracta Highest Velocity Pressure Velocity Lowest Pressure
Cavitation Vena Contracta Pressure Vapour Pressure Vapour Bubbles Collapse Vapour Bubbles Form
High Recovery Valves (Km= Fl2= 0.5) Line of sight valves; Butterfly, Ball Pressure Pressure Low Recovery Valves (Km = Fl2=0.8) Globe valves
Cavitation - Path Treatment • Cover exposed areas with resistant material • 316 Sst < 18 HRC • 416 Sst (Std trim material) 38 HRC min • 440C 56 HRC • Alloy 6 (Stellite) 36 to 44 HRC • Ceramic • Tungsten Carbide
Cavitation - Path Treatment • Cover exposed areas with resistant material • 316 Sst < 18 HRC • 416 Sst (Std trim material) 38 HRC min • 440C 56 HRC • Alloy 6 (Stellite) 36 to 44 HRC • Ceramic • Tungsten Carbide
Cavitation - Path Treatment Cavitrol III 1 Stage • Flow down • Holes directly opposing • Keeps any cavitation in centre of cage away from surfaces
Cavitation - Source Treatment • Treating the cause of cavitation • Use valve trim that avoids cavitation • Low recovery valve • High FL2( KM) • Change from rotary valve to globe Low Recovery Valve (Km)FL2 = 0.85 No Cavitation Pressure P1 P2 PV High Recovery Valve (Km) FL2 = 0.5 Cavitation
Hole shape The hole is designed to maximize flow without flow separation from the wall, and with enough recovery volume for the fluid from the previous orifice . Pilot hole and recovery volume flow Controlling orifice High Capacity Low Recovery
Hole Design - Control Flow Separation Any cavitation that does occur is outside cage wall Thin Plate Low Capacity Low Recovery Thick Plate High Capacity High Recovery Cavitrol Hole High Capacity Low Recovery
Staged Pressure Drop 1st Stage 2nd Stage 3rd Stage Standard Trim Staged Cavitrol Trim Note the uneven pressure drops. The first stage takes the majority of the drop so the last stage takes very little and can control Pvc very close to Pv. P1 P2 PV
NO SIGNIFICANT PRESSURE DROP MORE THAN 90% OF THE PRESSURE DROP VERY LOW INLET PRESSURE TO FINAL STAGE CAVITROL IV • CAV4 with Cavitrol IV Trim • Trim can take pressure drops up to 448 Bar • Protected seating surface eliminates significant pressure drop across seating surfaces • Trim can be used in other globe or angle valves • Staged clearance flows
CAV4 Special Products Group MINI CAV4 TRIM AVAILABLE IN 2” CLASS 1500 AND 2” CLASS 2500 DESIGN EHS VALVES 1” DIAMETER PORT, 3/4” TVL Cv RANGE - .1 TO 2.9 SAME LIMITS AND FEATURES AS STANDARD CAV4 USED FOR METHANOL LETDOWN
Velocity - Cavitrol Outlet Stage: Average velocity = 45 ft/sec Peak velocity - 57 ft/sec Second stage velocity lower than First stage
LC LC Separator Level Control Gas outlet Crude Inlet from well head Gas Oil Oil Water Oil level Control valve Water level Control valve
Challenges of these applications • Cavitation • High pressure drops • Erosion • High pressure drops • Sand and other particles • Corrosion • Sour conditions • Chloride stress cracking
Produced Water/Water Injection Valve Issues • High pressure drop • Can lead to damaging cavitation and erosion • Solid particulate can lead to plugging of conventional severe service trim • Tight shutoff required • Protects the valve from low flow damage when in the closed position • Possible corrosion issues • Issues with stress corrosion cracking need to be addressed • Depends upon H2S and chloride concentration Typical stacked disc trim
Erosion • Hard surfaces • decreases the amount or speed of damage • Alloy 6 • 440C • Tungsten Carbide • Ceramics Increasing erosion resistance
DST Flow Down W678-1