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KONTROLL VENTILER JAN O HJETLAND
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Fag disipliner Prosess Material Instrument ”Piping” Maling Innkjøp
Produksjons oppfølging
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Hvilken type kontroll ventiler har vi
Sete ventil (Globe) Kule ventil (Bal) Sving ventil (Butterfly)
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Hva er en kontroll ventil
En kontroll ventil er arbeideren i en prosess lup
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BUTTERFLY
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Ball
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Globe
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CAGE
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Separator Level Control
Gas outlet Crude Inlet from well head Gas Oil LC LC Oil Water Oil level Control valve Water level Control valve
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Ventildimensjonering og valg - fremgangsmåte
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 Gjenta beregningene med relevante ventildata
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KURVE
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Beregne ventilstørrelse - bakgrunn
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 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 og (inkompressible og kompressible medier) Disse standardene inneholder også metodikk for støyberegninger
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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
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Aerodynamiske støykilder
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Linje-kilde Tverrsnitt av rør R 1 + r LpA = F + 10 Log R + r
For hver dobling av avstand, tapes 3 dBa R LpA = F + 10 Log 1 + r R + r
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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
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Whisper III Flow passes through small holes Increases frequency
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
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Whisper III C3 C/d = 3.4 dP/P1< 0.99 B3 C/d = 2.7 dP/P1 < 0.75
1.6 mm C/d = 3.4 dP/P1< 0.99 B3 1.6 mm C/d = 2.7 dP/P1 < 0.75 P2 P1 A3 1.6 mm C/d = 2.0 dP/P1 < 0.6 Air Flow
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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
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WhisperFlo Flow Passage
Outlet Inlet
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Lyddemper
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Reduksjon av støy
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Begrense støy-generering
Globe ventil med diffuser
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VESKE FLASING CAVITATION
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Liquid Flow through an Orifice
Vena Contracta Pressure Highest Velocity Velocity Lowest Pressure
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Cavitation Vena Contracta Vapour Bubbles Collapse Vapour Bubbles Form
Pressure Vapour Pressure Vapour Bubbles Collapse Vapour Bubbles Form
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High Recovery Valves (Km= Fl2= 0.5) Line of sight valves;
Pressure High Recovery Valves (Km= Fl2= 0.5) Line of sight valves; Butterfly, Ball Pressure Low Recovery Valves (Km = Fl2=0.8) Globe valves
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Cavitation Damage
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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
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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
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Cavitation - Path Treatment
Select body style that directs the cavitation away from surfaces ( Isolates ) Angle body Flow down Liner (Hardened Material) Hardened trim Micro-Flat Trim for low Cv requirements Cavitation is confined to the centre of the outlet passage
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Cavitation - Path Treatment
Select body style that directs the cavitation away from surfaces Vee Ball Valve Reverse flow Stellited ball Forward Flow Reverse Flow
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Cavitation - Path Treatment
Aspiration Inject air into cavitating flow stream Air bubbles absorb energy released in bubble collapse
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Cavitation - Path Treatment
Cavitrol III 1 Stage Flow down Holes directly opposing Keeps any cavitation in centre of cage away from surfaces
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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
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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
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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
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Staged Pressure Drop 1st Stage 2nd Stage 3rd Stage Standard Trim
Staged Cavitrol Trim P1 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. P2 PV
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3 Stage Cavitrol III Trim
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CAVITROL IV CAV4 with Cavitrol IV Trim
NO SIGNIFICANT PRESSURE DROP MORE THAN 90% OF THE VERY LOW INLET 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
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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
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Application Hole size Cav III 1-stage hole size = ” or 0.125” diameter Cav III 2 and 3 stage smallest hole size (in the first stage sleeve) = 0.049” diameter Larger holes for can be used for less plugging, but will reduce cavitation protection. If larger holes are used more stages are required.
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Velocity - Cavitrol Second stage velocity lower than First stage
Outlet Stage: Average velocity = 45 ft/sec Peak velocity ft/sec Second stage velocity lower than First stage
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Separator Level Control
Gas outlet Crude Inlet from well head Gas Oil LC LC Oil Water Oil level Control valve Water level Control valve
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Produced Water/Water Injection Valves
Raw production, from the wellhead, comes typically in the form of a mixture of free water, oil/water emulsion, oil and solids. This combination is also referred to as BS&W (basil sediment and water) and oil. The raw production from the wellhead is then piped to gathering points, known as satellites. From there it is piped to the production facility or battery. This raw production then enters the Free Water Knockout Vessel (FWKO) where the free water and loose solids are separated from the remaining oil/oil-water emulsion and stored in the produced water tanks. The remaining oil/oil-water emulsion then proceeds to the treater vessels where a combination of heat and chemicals (emulsion breakers) are used to break the emulsion and produce clean oil and produced water and solids. Clean oil then proceeds to storage or shipping. The produced water from the treaters is transferred to tanks to hold for disposal. Depending on residence time in the tanks, some of the solids may settle out of the water and residual oil in the water floats to the surface. This oil layer is skimmed off the top and recycled through the plant to recover this additional oil. In smaller production facilities, this water may be disposed of directly from the tanks. In larger facilities, there is often an additional water treatment vessel known as a dissolved air flotation (DAF) unit that further cleans the water. After the DAF unit, the water is either sent through filters, which are usually sand or multimedia filters or through hydrocyclones to remove the last traces of oil. After final filtration, the water is used for steam generation, discharged to agricultural canals or rivers or re-injected downhole. As oil wells mature, the ratio of water to oil increases. This is because the formation “waters out” due to the water injection process. Water becomes a significant byproduct of oil and gas production. For example more than 7m3 of water is produced for every cubic meter of oil or gas equivalent (10bbl water/bbl oil) obtained from gas and oil wells in the continental U.S.
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Challenges of these applications
Cavitation High pressure drops Erosion Sand and other particles Corrosion Sour conditions Chloride stress cracking
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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 The valves used in this process will generally see cavitation involving high-pressure drops and erosion damage caused by the sand and other particulate present during separation. Small holed trim and stacked disk designs have been tried in the past but have failed due to the holes clogging. Corrosion is also an important consideration. Produced water tends to contain some amounts of H2S and chlorides. It is very rare to find a produced water valve that does not need to NACE certified. Also consider, as the well ages, more and more H2S is usually produced. Consider 316/Alloy 6 combinations or certain grades of duplex for combating corrosion. Typical stacked disc trim
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Erosion Hard surfaces decreases the amount or speed of damage Alloy 6
Tungsten Carbide Ceramics Increasing erosion resistance
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Better Solution - Fisher NotchFlo DST
Pressure staging reduces vibration Available in 4 stages and capable of up to 180 Bar of pressure drop Ability to pass particles up to 12 mm diameter Protected seat maintains shutoff integrity Hardened materials resist erosion damage Can be used for globe or angle valve configurations
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Trash Tolerance - Notchflo vs. DST
1” 2” 3” 4” 6” 8” 0.1” 0.2” 0.3” 0.4” 0.35” 0. 5” .375” .75” Particle Size NotchFlo DST .25”
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DST “Dirty Service Trim”
W6787-1
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DST Flow Down W678-1
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Rotary Actuator
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HOOK UP
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DVC6000
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E.SEAL
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