Smart DP Flow Metering A summary of Established Technology and Latest Innovation Gary Fish
DP Flow Measurement Established Technology Large range of line sizes, materials, connection interfaces, etc Customised solutions New innovations and improvements
Square Edged Orifice Plate ISO 5167-2 β range 0.1 to 0.75 Min Re D 5 x 10 3 Max Re D Permanent Pressure loss: β dependent between 42% and 98% of ΔP Uncalibrated Uncertainty C d 0.5% (for β between 0.2 & 0.6) General Flow metering applications- gas allocation and fiscal standard
Conical Entrance Orifice Plate ISO TR 15377 β range 0.1 to 0.316 Min Re D 80 Max Re D 6.3 x 10 4 (for β 0.316) Uncalibrated Uncertainty C d 2% Application viscous fluids
Quarter-Circle Orifice Plate ISO TR 15377 β range 0.245 to 0.6 Min Re D 245 (for β 0.245) Max Re D 6 x 10 4 (for β 0.6) Uncalibrated Uncertainty C d 2% to 2.5% Application viscous fluids
Eccentric Orifice Plate ISO TR 15377 β range 0.46 to 0.84 Min Re D 4.2 x 10 3 Max Re D 8.4 x 10 5 Uncalibrated Uncertainty C d 1% to 2% (can be calibrated to improve) Application entrained gas in liquid service, entrained liquid in gas service, sediments, etc
ISA 1932 Nozzle ISO 5167-3 β range 0.3 to 0.8 Min Re D 2 x 10 4 (for β 0.44 or greater) Max Re D 1 x 10 7 Uncalibrated Uncertainty C d 0.8% to 1.2% (β dependent) Permanent Pressure loss: between 25% and 80% of ΔP (typical) high velocity, steam flow.
Long Radius Nozzle ISO 5167-3 β range 0.2 to 0.8 Min Re D 1 x 10 4 Max Re D 1 x 10 7 Uncalibrated Uncertainty C d 2% Permanent Pressure loss: between 24% and 92% of ΔP (typical) high velocity, steam flow.
Venturi Nozzle ISO 5167-3 β range 0.316 to 0.775 Min Re D 1.5 x 10 5 Max Re D 2 x 10 6 Uncalibrated Uncertainty C d 1.2% to 1.7% Permanent Pressure loss: between 5% and 20% of ΔP (typical) high velocity, steam flow. Low permanent pressure loss
Machined Venturi ISO 5167-4 β range 0.4 to 0.75 Min Re D 2 x 10 5 Max Re D 1x 10 6 Uncalibrated Uncertainty C d 1% (for Re D limits shown) Re D limits increased according to Annex B with increased uncertainty Permanent Pressure loss: between 5% and 20% of ΔP General Flow metering applications- gas allocation, high velocity, low maintenance and intervention. Low permanent pressure loss.
Fabricated Venturi ISO 5167-4 β range 0.4 to 0.7 Min Re D 2 x 10 5 Max Re D 2 x 10 6 Uncalibrated Uncertainty C d 1.5% (for Re D limits shown) Re D limits increased according to Annex B with increased uncertainty Permanent Pressure loss: between 5% and 20% of ΔP General Flow metering applications- gas allocation, high velocity, low maintenance and intervention. Low permanent pressure loss.
As Cast Venturi ISO 5167-4 β range 0.3 to 0.75 Min Re D 2 x 10 5 Max Re D 2 x 10 6 Uncalibrated Uncertainty C d 0.7% (for Re D limits shown) Re D limits increased according to Annex B with increased uncertainty Permanent Pressure loss: between 5% and 20% of ΔP General Flow metering applications- gas allocation, high velocity, low maintenance and intervention. Low permanent pressure loss.
Cone Meter ISO 5167-5 β range 0.45 to 0.75 Min Re D 8 x 10 4 Max Re D 1.2 x 10 7 Uncalibrated Uncertainty C d 5% Permanent Pressure loss: between 48% and 72% of ΔP (typical) General Metering applications, allocation, shorter overall installation than Venturi meter
Wedge Meter ISO 5167-6 (not yet published) β range 0.377 to 0.791 Min Re D 1 x 10 4 note 1 Max Re D 9 x 10 6 Uncalibrated Uncertainty C d 4% Permanent Pressure loss: between 47% and 79% of ΔP (typical) Suspended solids, viscous fluids note 1 Note 1 : Standard will be based upon available data Wedge Meters have been known to operate at Re =500, but will require calibration- resulting in much lower uncertainty also.
Dall Tube No International Standard β range 0.3 to 0.8 Min Re D 5 x 10 4 Max Re D Uncalibrated Uncertainty C d 3% Permanent Pressure loss: between 2.5% and 8% of ΔP (typical) Clean process fluids, very low pressure loss requirements
Comparison table for DP Devices Limits of use Device Standard Line Size (mm) β Re D Min Max Min Max Min Max Uncertainty C d (UNCALIBRATED) Permanent Pressure loss (% of ΔP) SQUARE EDGED ORIFICE PLATE ISO 5167-2 50 1000 0.1 0.75 5 x 10 3 0.5% NOTE 1 42% to 98% CONICAL ENTRANCE ORIFICE PLATE ISO TR 15377 25 500 0.1 0.316 80 6.3 x 10 4 2% 86% to 98% QUARTER-CIRCLE ORIFICE PLATE ISO TR 15377 25 500 0.245 0.6 245 6 x 10 4 2% to 2.5% 53% to 91% ECCENTRIC ORIFICE PLATE ISO TR 15377 100 1000 0.46 0.84 4.2 x 10 3 8.4 x 10 5 1% to 2% 36% to 77% ISA 1932 NOZZLE IS0 5167-3 50 500 0.3 0.8 2 x 10 4 1 x 10 7 0.8% to 1.2% 25% to 83% LONG RADIUS NOZZLE ISO 5167-3 50 630 0.2 0.8 1 x 10 4 1 x 10 7 2% 24% to 92% VENTURI NOZZLE ISO 5167-3 65 500 0.316 0.775 1.5 x 10 5 2 x 10 6 1.2% to 1.7% 5% to 20% MACHINED VENTURI ISO 5167-4 50 250 0.4 0.75 2 x 10 5 1 x 10 6 1% 5% to 20% FABRICATED VENTURI ISO 5167-4 200 1200 0.4 0.7 2 x 10 5 2 x 10 6 1.50% 5% to 20% AS CAST' VENTURI ISO 5167-4 100 800 0.3 0.75 2 x 10 5 2 x 10 6 0.70% 5% to 20% CONE METER ISO 5167-5 50 500 0.45 0.75 8 x 10 4 1.2 x 10 7 5% 48% to 72% WEDGE METER ISO 5167-6 NOTE 2 50 600 0.377 0.791 1 x 10 4 9 x 10 6 4% 47% to 79% DALL TUBE NO STANDARD 150 3000 0.3 0.8 5 x 10 4 3% 2.5% to 8% Notes 1 For β between 0.2 and 0.6 2 Not yet published All C d Uncertainties can be reduced with flow calibration over entire operating range
Upstream Straight Length requirements 1off 90 o bend Generic DP Device β lim L β lim L β L ORIFICE 0.1 6D 0.75 44D NOZZLE 0.2 10D 0.8 46D VENTURI 0.3 8D 0.75 16D CONE METER 0.45 3D 0.75 6D WEDGE METER 0.377 7D 0.791 7D DALL TUBE 0.3 3D 0.8 13D 0.5 22D 0.5 14D 0.5 9D 0.5 3D 0.5 7D 0.5 4D Upsteam lengths may be reduced with C d uncertainties increasing
Upstream Straight Length requirements 1off 90 o bend Generic DP Device Uncalibrated C d Uncertainty β L ORIFICE (Square edged) 0.50% 0.5 22D NOZZLE (ISA 1932) 0.80% 0.5 14D VENTURI (Machined) 1.00% 0.5 9D CONE METER 5% 0.5 3D WEDGE METER 4% 0.5 7D DALL TUBE 3% 0.5 4D
Upstream Straight Length requirements 1off 90 o bend Generic DP Device Uncalibrated C d Uncertainty β L ORIFICE (Square edged) 1.0% 0.5 9D NOZZLE (ISA 1932) 1.3% 0.5 7D VENTURI (Machined) 1.5% 0.5 3D CONE METER 5%* 0.5 3D* WEDGE METER 4%* 0.5 7D* DALL TUBE 3.5% 0.5 3D *No data published in ISO regarding shorter length uncertainty
Differential Pressure Transmitter Technology Largest contribution to enhanced DP meter uncertainty in recent years Example 1 : Yokogawa EJX130A, ref accuracy :+/-0.04% of span (3σ) Example 2: Rosemount 3051CD (ranges 2-4), ref accuracy :+/-0.04% of span (3σ) Full transparent uncertainty analysis can be carried out for DP meters
DP Meter Uncertainty Analysis
Myth : The Differential Pressure is limited to 500mbar for an orifice plate
Limits for Orifice Plate DP End User/Operator specifications stating for instance DP limited to 500mbar Why? There is no need providing : Permanent Pressure loss is acceptable Orifice Plate Elastic or Plastic Deformation is considered DP is within expansibility limits
Myth : The flow turndown for DP devices is only 3:1
Turndown / Rangeability Claim / belief: You only get 3:1 with an orifice Turndown/rangeability is the ratio of the largest to smallest flow rate that can be metered to the meter s stated flow rate prediction uncertainty at a stated confidence level. For mass flow uncertainty below 0.8% we need the DP uncertainty <1%. [200, 2000] = 10:1 on DP ~3.2:1 flow range With 1 DP Transmitter
DP H: 0-2000mbar DP M: 0-300mbar DP L: 0-50mbar Turndown / Rangeability Example, stacked transmitters Example : 30m/s, 25kg/m 3, 12 pipe ~260,000 Sm 3 /h Beta = 0.6, DP = ~2000mbar
Turndown / Rangeability Example, stacked transmitters 30m/s, 25kg/m 3, 12 pipe 260,000Sm 3 /h Beta = 0.6, DP = ~2000mbar DP H: 0-2000mbar DP M: 0-300mbar DP L: 0-50mbar min: 30% of max flow -> 3.3:1 min: 11% of max flow -> 9.1:1 min: 4.5% of max flow -> 22:1
Turndown / Rangeability Claim / belief: You only get 3:1 with an orifice 0 m/s? 3.3% of flow rate (1 m/s) +/-0.8% 100%/3.3% = 30 i.e. turndown = 30:1 e.g. USM 100% of flow rate (30 m/s) 0 m/s 4.5% of flow rate (1.35 m/s) +/-0.8% 100%/4.5% = 22 i.e. turndown = 22:1 e.g. Orifice 100% of flow rate (30 m/s)
Turndown / Rangeability Similar Claim Turndown / belief: to USM in practice You only get 3:1 with an orifice 0 m/s 3.3% of flow rate (1 m/s) +/-0.8% 100%/3.3% = 30 i.e. turndown = 30:1 e.g. USM 100% of flow rate (30 m/s) 0 m/s 4.5% of flow rate (1.35 m/s) +/-0.8% 100%/4.5% = 22 i.e. turndown = 22:1 e.g. Orifice 100% of flow rate (30 m/s) Difference? 30:1 from 22:1 is an increase in flow range of (1.2/95.5) 1.26%
Turndown / Rangeability Later life example. Reduced Pressure and Flow E.g. Max flow: 3 m/s, (i.e. 15,500 Sm 3 /h) USM fixed at 30 m/s > U (m/s) > 1 m/s, (10% of USM full scale flow). 0.6β orifice meter produces 12mbar, (8% of orifice meter full scale flow). Easy improvement :change the beta 0.2β orifice meter produces 1150mbar 1150 DP mbar 5 gives 3 U (m/s) 0.2 150:1
Myth : The permanent pressure loss is always too high with DP devices
Permanent Pressure Loss Higher PPL may sometimes be significant, but meter PPL should be seen in context.
Permanent Pressure Loss 12, sch 40 gas (ordinary) pipe 40 Bar, 15 0 C, 31.8 kg/m 3, 15 m/s, 140 MMSCFD Components in pipe: Globe valve (3/4 open) for control Open butterfly valve (emergency shut off) 4 elbows, T-junction, sample probe, 2 thermowells A flow conditioner & flow meter What is the PPL across the system? What relative impact on overall PPL does the meter system have?
Permanent Pressure Loss P loss K loss V * 2 2 av
Permanent Pressure Loss P loss K loss V * 2 2 av
Permanent Pressure Loss The PPL is dependent on the length of pipe. P loss K loss V * 2 2 av Most pipe systems are long, that s why it s convention to call pipe loss the major loss!
Permanent Pressure Loss Often pipe losses dwarf any meter PPL. (Gas transmission compressor stations are > 40 miles apart, platform to shore is miles long etc.) Other calibrated DP devices can offer the measurement accuracy requirements and low pressure losses eg Venturi, Dall tube, etc
Myth : DP devices don t have diagnostic capabilities
Incorrect Metrology Data Excessive Flow Disturbance Contamination Build Up Saturated DP Tx Drifting DP Tx Incorrectly Spanned DP Tx DP Below Tx Range Two Phase Flow Electrical Loop Integrity Plugged Lines Process Leakage Improved Overall Safety Integrity Etc,Etc.. Validation / Diagnostics Combination of advancement in transmitter technology and specialised innovative developments the following diagnostics are available for DP meters
Validation / Diagnostics - Orifice Excellent diagnostics No calibration required. 3 x Flow Rate Comparisons 3 x DP Ratio Comparisons Reasonably objective 1 x DP Integrity Check DP Synchronisation / turbulence checks
Thankyou! : Questions?