Measurement Devices and Analysers

NeqSim provides a comprehensive set of measurement devices and process analysers for monitoring fluid properties, compositions, and process conditions.

Overview

Measurement devices in NeqSim fall into several categories:

Fluid Composition Analysers

CombustionEmissionsCalculator

Calculates CO2 emissions from fuel gas combustion based on stream composition.

import neqsim.process.measurementdevice.CombustionEmissionsCalculator;

// Create fuel gas stream
Stream fuelGas = new Stream("Fuel Gas", gas);
fuelGas.setFlowRate(1000.0, "kg/hr");
fuelGas.run();

// Create emissions calculator
CombustionEmissionsCalculator emissionsCalc =
    new CombustionEmissionsCalculator("CO2 Calculator", fuelGas);

// Get CO2 emissions rate
double co2Emissions = emissionsCalc.getMeasuredValue("kg/hr");  // kg CO2/hr

CO2 Emission Factors (kg CO2 per kg component):

Component Emission Factor
Methane 2.75
Ethane 3.75
Propane 5.50
n-Butane 6.50
n-Pentane 7.50
Hexane 8.50
Nitrogen 0.0
CO2 0.0

NMVOCAnalyser

Calculates the mass flow rate of Non-Methane Volatile Organic Compounds (nmVOCs).

import neqsim.process.measurementdevice.NMVOCAnalyser;

// Create analyser
NMVOCAnalyser nmvocAnalyser = new NMVOCAnalyser("NMVOC Monitor", ventStream);

// Get nmVOC flow rate
double nmvocFlow = nmvocAnalyser.getMeasuredValue("kg/hr");
double nmvocYearly = nmvocAnalyser.getnmVOCFlowRate("tonnes/year");  // tonnes/year

Components included in nmVOC calculation:

Dew Point Analysers

HydrocarbonDewPointAnalyser

Calculates the hydrocarbon dew point temperature at a specified pressure.

import neqsim.process.measurementdevice.HydrocarbonDewPointAnalyser;

HydrocarbonDewPointAnalyser hcdp =
    new HydrocarbonDewPointAnalyser("HC Dew Point", gasStream);
hcdp.setReferencePressure(50.0, "bara");

double dewPointC = hcdp.getMeasuredValue("C");  // hydrocarbon dew point, degC

WaterDewPointAnalyser

Calculates the water dew point temperature.

import neqsim.process.measurementdevice.WaterDewPointAnalyser;

WaterDewPointAnalyser wdp =
    new WaterDewPointAnalyser("Water Dew Point", gasStream);
wdp.setReferencePressure(50.0, "bara");

double waterDewPoint = wdp.getMeasuredValue("C");  // water dew point, degC

CricondenbarAnalyser

Calculates the cricondenbar (maximum pressure on phase envelope).

import neqsim.process.measurementdevice.CricondenbarAnalyser;

CricondenbarAnalyser cricondenbar = new CricondenbarAnalyser(gasStream);
double maxPressure = cricondenbar.getMeasuredValue("bara");  // cricondenbar, bara

HydrateEquilibriumTemperatureAnalyser

Calculates the hydrate equilibrium temperature at the stream pressure.

import neqsim.process.measurementdevice.HydrateEquilibriumTemperatureAnalyser;

HydrateEquilibriumTemperatureAnalyser hydrateAnalyser =
    new HydrateEquilibriumTemperatureAnalyser(gasStream);
double hydrateTemp = hydrateAnalyser.getMeasuredValue("C");  // hydrate formation temperature, degC

Vibration Analysis

FlowInducedVibrationAnalyser

Calculates Flow-Induced Vibration (FIV) risk indicators for pipelines.

import neqsim.process.measurementdevice.FlowInducedVibrationAnalyser;

// Create pipeline
PipeBeggsAndBrills pipeline = new PipeBeggsAndBrills("Export", feed);
pipeline.setLength(5000.0);
pipeline.setDiameter(0.3048);  // 12 inch
pipeline.setThickness(0.0127); // 0.5 inch
pipeline.run();

// Create FIV analyser
FlowInducedVibrationAnalyser fivAnalyser =
    new FlowInducedVibrationAnalyser("FIV Monitor", pipeline);
fivAnalyser.setSupportArrangement("Stiff");
fivAnalyser.setSupportDistance(3.0);  // meters

// Get FIV metrics
fivAnalyser.setMethod("LOF");  // Likelihood of Failure
double lof = fivAnalyser.getMeasuredValue("");

fivAnalyser.setMethod("FRMS");  // Fatigue Root Mean Square
double frms = fivAnalyser.getMeasuredValue("");

Support Arrangements:

Analysis Methods:

Process Monitors

PressureTransmitter

Monitors pressure at a measurement point.

import neqsim.process.measurementdevice.PressureTransmitter;

PressureTransmitter pt = new PressureTransmitter(separator);
pt.setUnit("bara");
double pressure = pt.getMeasuredValue();

TemperatureTransmitter

Monitors temperature at a measurement point.

import neqsim.process.measurementdevice.TemperatureTransmitter;

TemperatureTransmitter tt = new TemperatureTransmitter(heatExchanger);
tt.setUnit("C");
double temperature = tt.getMeasuredValue();

LevelTransmitter

Monitors liquid level in vessels.

import neqsim.process.measurementdevice.LevelTransmitter;

LevelTransmitter lt = new LevelTransmitter(separator);
lt.setUnit("%");
double level = lt.getMeasuredValue();

VolumeFlowTransmitter

Monitors volumetric flow rate.

import neqsim.process.measurementdevice.VolumeFlowTransmitter;

VolumeFlowTransmitter vft = new VolumeFlowTransmitter(stream);
vft.setUnit("m3/hr");
double volumeFlow = vft.getMeasuredValue();

VenturiFlowMeter

All five differential-pressure flow meters below share a common base, DifferentialPressureFlowMeter (ISO 5167-1 general principles), which supplies the geometry (setGeometry/setPipeDiameter/setThroatDiameter/getBetaRatio), the differential pressure (explicit or via a linked DifferentialPressureTransmitter), the gas density/isentropic exponent/dynamic viscosity readers (each overridable), the Reynolds-number iteration, and the mass/actual-volume/standard-volume accessors. They differ only in the discharge coefficient and the expansibility factor, ExpansibilityModel (ORIFICE, ISENTROPIC or CONE).

Derives mass, actual volume and standard volume flow from a measured differential pressure across a classical Venturi tube, using the ISO 5167-1 general equation with the ISO 5167-4 Venturi expansibility factor. The differential pressure is either set explicitly or read from a linked DifferentialPressureTransmitter, which takes precedence when present.

import neqsim.process.measurementdevice.VenturiFlowMeter;

VenturiFlowMeter meter = new VenturiFlowMeter("FT-001", stream);
meter.setGeometry(205.1, 138.1, "mm");   // pipe diameter D, throat diameter d
meter.setDischargeCoefficient(0.985);    // ISO 5167-4: 0.995 machined, 0.984 as-cast, 0.985 welded
meter.setDifferentialPressure(300.0, "mbar");

double massFlow = meter.getMassFlowRate("kg/hr");
double actualFlow = meter.getVolumeFlowRate("m3/hr");
double standardFlow = meter.getStandardVolumeFlowRate("Sm3/hr");
boolean withinIso = meter.isWithinIso5167ValidityRange();  // p2/p1 >= 0.75

Wet-gas correction (ISO/TR 11583)

A Venturi over-reads when liquid is present. Selecting the ISO/TR 11583 correlation solves the wet-gas equations iteratively and returns the gas mass flow:

\[q_{m,gas} = \frac{C}{\sqrt{1-\beta^4}}\,\varepsilon\,\frac{\pi d^2}{4}\,\frac{\sqrt{2\,\Delta p\,\rho_{1,gas}}}{\Phi}\] \[\Phi=\sqrt{1+C_{Ch}X+X^2},\qquad X = \frac{q_{m,liquid}}{q_{m,gas}}\sqrt{\frac{\rho_{1,gas}}{\rho_{liquid}}}\] 
import java.util.List;

meter.setWetGasCorrelation(VenturiFlowMeter.WetGasCorrelation.ISO_TR_11583);
meter.setSurfaceTensionFactor(VenturiFlowMeter.H_HYDROCARBON);  // 1.0 HC, 1.35 water, 0.79 wet steam

// Supply the liquid load in one of four ways:
meter.setLiquidFromStream(true);              // from the stream's own phase split
// meter.setLiquidToGasMassRatio(0.5);        // from a recent separator test
// meter.setLiquidMassFlowRate(2.5, "kg/sec");// absolute rate
// meter.setPressureLoss(0.125, "bar");       // ISO/TR 11583 6.4.5, needs a third tapping

double gasFlow = meter.getMassFlowRate("kg/sec");
double x = meter.getLockhartMartinelliParameter();
double phi = meter.getOverReadingFactor();
double uncertainty = meter.getRelativeUncertaintyOfCOverPhi();   // 6.5 Table 2
List<String> issues = meter.getValidityViolations();             // empty when in range

ISO/TR 11583 replaces the discharge coefficient by default. In wet-gas mode the value passed to setDischargeCoefficient is overridden by the wet-gas $C$ of Equation (4) (which tends to 1 rather than 0.985), unless setUseWetGasDischargeCoefficient(false) is called, in which case the configured (e.g. in-service-calibrated) $C$ is kept and only the $\Phi$ over-reading is applied.

Limits of use (reported, not enforced): $0.4\le\beta\le0.75$, $0<X\le0.3$, $Fr_{gas,th}>3$, $\rho_{gas}/\rho_{liquid}>0.02$, $D\ge50$ mm. The Technical Report covers a single liquid at roughly 95 % gas volume fraction or more and states it “is not intended for the oil and gas industry”; combining an aqueous and a hydrocarbon phase into one effective liquid is an extension beyond it. Gas and liquid density can be supplied from sampling with setGasDensity / setLiquidDensity instead of being read from the stream, as the Technical Report advises against in-line densitometers in wet-gas service.

Wet-gas correction (de Leeuw, 1997)

The de Leeuw (1997) correlation, reported by R.N. Steven, “Wet gas metering with a horizontally mounted Venturi meter”, Flow Measurement and Instrumentation 12 (2002) 361-372, uses the same Chisholm-form over-reading equation as ISO/TR 11583 but with a purely Froude-number-based exponent that has no diameter-ratio term, and it never replaces the discharge coefficient:

\[n = 0.41 \ \ (Fr_{gas}\le 1.5), \qquad n = 0.606\left(1-e^{-0.746\,Fr_{gas}}\right) \ \ (Fr_{gas}\ge 1.5)\] 
meter.setWetGasCorrelation(VenturiFlowMeter.WetGasCorrelation.DE_LEEUW);
meter.setLiquidFromStream(true);   // or setLiquidToGasMassRatio / setLiquidMassFlowRate

double gasFlow = meter.getMassFlowRate("kg/sec");
double phi = meter.getOverReadingFactor();
boolean inRange = meter.isWithinDeLeeuwValidityRange();

Because C is never replaced, setUseWetGasDischargeCoefficient has no effect on this correlation; an in-service-calibrated discharge coefficient is safe by construction. Steven (2002) independently benchmarked de Leeuw against five general two-phase Orifice Plate correlations and one other Venturi correlation on NEL wet-gas-loop data and found it the best performer (RMS fractional deviation 0.0211). However, de Leeuw’s own data was taken on a 4 in Venturi with $\beta=0.401$ and $n$ has no $\beta$ term, so a different diameter ratio is an extrapolation, and there is no published $X$ range or permanent-pressure-loss route (unlike ISO/TR 11583 6.4.5). getValidityViolations() reports the $Fr_{gas}\ge 0.5$ lower bound and a $\beta$-departure note.

OrificeFlowMeter

Orifice plate following ISO 5167-2. The discharge coefficient is the Reader-Harris/Gallagher (1998) equation, which depends on the pipe Reynolds number and on the pressure-tapping arrangement (OrificeFlowMeter.TappingArrangement: CORNER, D_AND_D_HALF or FLANGE); the expansibility factor is ExpansibilityModel.ORIFICE.

import java.util.List;
import neqsim.process.measurementdevice.OrificeFlowMeter;

OrificeFlowMeter meter = new OrificeFlowMeter("FT-200", stream);
meter.setGeometry(200.0, 100.0, "mm");
meter.setTappingArrangement(OrificeFlowMeter.TappingArrangement.FLANGE);
meter.setDifferentialPressure(300.0, "mbar");

double massFlow = meter.getMassFlowRate("kg/hr");
List<String> issues = meter.getValidityViolations();  // 12.5 mm <= d, 50-1000 mm D, 0.1-0.75 beta, Re,D limits

Wet-gas correction (ISO/TR 11583 Clause 7)

Selecting the ISO/TR 11583 Clause 7 orifice method returns the gas mass flow using the same Chisholm-form over-reading equation as the Venturi tube (Clause 6), but the discharge coefficient is never replaced — Clause 7.5.2 keeps the plain Reader-Harris/Gallagher $C$, evaluated at the Reynolds number that would occur if only the gas were flowing:

\[q_{m,gas} = \frac{C}{\sqrt{1-\beta^4}}\,\varepsilon\,\frac{\pi d^2}{4}\,\frac{\sqrt{2\,\Delta p\,\rho_{1,gas}}}{\Phi}\] \[\Phi=\sqrt{1+C_{Ch}X+X^2},\qquad C_{Ch} = \left(\frac{\rho_{liquid}}{\rho_{1,gas}}\right)^{n} + \left(\frac{\rho_{1,gas}}{\rho_{liquid}}\right)^{n}\]

The exponent $n$ depends only on the gas densiometric Froude number and has no diameter-ratio term (unlike Venturi’s beta-reduced exponent):

\[n = 0.214 \ \ (0.2\le Fr_{gas} < 1.5), \qquad n = \left(\frac{1}{\sqrt{2}} - \frac{0.3}{\sqrt{Fr_{gas}}}\right)^2 \ \ (Fr_{gas} > 1.5)\] 
import java.util.List;

meter.setWetGasCorrelation(OrificeFlowMeter.WetGasCorrelation.ISO_TR_11583);

// Supply the liquid load in one of four ways:
meter.setLiquidFromStream(true);               // from the stream's own phase split
// meter.setLiquidToGasMassRatio(0.5);         // from a recent separator test
// meter.setLiquidMassFlowRate(2.5, "kg/sec"); // absolute rate
// meter.setPressureLoss(0.45, "bar");         // ISO/TR 11583 7.5.5, needs 0.5 <= beta <= 0.68

double gasFlow = meter.getMassFlowRate("kg/sec");
double x = meter.getLockhartMartinelliParameter();
double froude = meter.getGasDensiometricFroudeNumber();
double phi = meter.getOverReadingFactor();
List<String> issues = meter.getValidityViolations();   // Clause 7 limits when wet-gas mode is active

The discharge coefficient is never replaced. Unlike VenturiFlowMeter’s ISO/TR 11583 Clause 6 method, orifice Clause 7 always uses the plain dry-gas $C$, so there is no useWetGasDischargeCoefficient-style guard and an in-service-calibrated $C$ is not disturbed beyond the $\Phi$ over-reading division.

Limits of use (reported, not enforced): $0.24\le\beta\le0.73$, $0<X\le0.3$, $Fr_{gas}\ge0.2$, $\rho_{gas}/\rho_{liquid}>0.014$, $D\ge50$ mm. When the 7.5.5 pressure-loss route is used (no explicit liquid rate or ratio given, $0.5\le\beta\le0.68$), two additional bounds on $X$ and the density ratio are also checked. As with the Venturi tube, an aqueous and a hydrocarbon liquid phase are combined into one effective liquid when setLiquidFromStream(true) is used, which is an extension beyond the Technical Report.

NozzleFlowMeter

The four nozzle sub-types of ISO 5167-3, selected with NozzleFlowMeter.NozzleType: ISA_1932 (Reynolds-dependent), LONG_RADIUS (Reynolds-dependent), THROAT_TAPPED (Reynolds-dependent, piecewise in Re,d) and VENTURI_NOZZLE (constant C). All four share the isentropic expansibility factor, ExpansibilityModel.ISENTROPIC.

import neqsim.process.measurementdevice.NozzleFlowMeter;

NozzleFlowMeter meter = new NozzleFlowMeter("FT-300", stream);
meter.setNozzleType(NozzleFlowMeter.NozzleType.ISA_1932);
meter.setGeometry(200.0, 100.0, "mm");
meter.setDifferentialPressure(300.0, "mbar");

double massFlow = meter.getMassFlowRate("kg/hr");

ConeFlowMeter

Cone meter following ISO 5167-5. The cone has no physical throat bore: set the pipe diameter and the cone diameter with setGeometry, and the diameter ratio $\beta=\sqrt{1-d_c^2/D^2}$ is derived. The discharge coefficient is the constant 0.82 of an uncalibrated meter; the expansibility factor is ExpansibilityModel.CONE.

import neqsim.process.measurementdevice.ConeFlowMeter;

ConeFlowMeter meter = new ConeFlowMeter("FT-400", stream);
meter.setGeometry(200.0, 160.0, "mm");  // pipe diameter D, cone diameter dc
meter.setDifferentialPressure(300.0, "mbar");

double massFlow = meter.getMassFlowRate("kg/hr");
double coneDiameter = meter.getConeDiameter("mm");

WedgeFlowMeter

Wedge meter following ISO 5167-6. The wedge has no physical throat bore either: set the pipe diameter and the wedge gap height with setGeometry, or the wedge ratio $h/D$ directly with setWedgeRatio, and the diameter ratio is derived per ISO 5167-6 Formula (3). The discharge coefficient is $C=0.77-0.09\beta$ of an uncalibrated meter; since no wedge-specific expansibility data has been published, ISO 5167-6 applies the same isentropic factor as the nozzles and the classical Venturi tube, ExpansibilityModel.ISENTROPIC.

import neqsim.process.measurementdevice.WedgeFlowMeter;

WedgeFlowMeter meter = new WedgeFlowMeter("FT-500", stream);
meter.setGeometry(200.0, 80.0, "mm");  // pipe diameter D, wedge gap height h
meter.setDifferentialPressure(300.0, "mbar");

double massFlow = meter.getMassFlowRate("kg/hr");
double wedgeRatio = meter.getWedgeRatio();  // h / D

Safety Devices

GasDetector

Simulates gas detection for safety systems.

import neqsim.process.measurementdevice.GasDetector;

GasDetector gasDetector = new GasDetector("Gas Detector 1", stream);
gasDetector.setDetectionLimit(20.0);  // % LEL
boolean gasDetected = gasDetector.isTriggered();

FireDetector

Simulates fire detection for safety systems.

import neqsim.process.measurementdevice.FireDetector;

FireDetector fireDetector = new FireDetector("Fire Detector 1");
fireDetector.setTemperatureThreshold(65.0);  // °C
boolean fireDetected = fireDetector.isTriggered();

Quality Analysers

MolarMassAnalyser

Calculates the molar mass of a stream.

import neqsim.process.measurementdevice.MolarMassAnalyser;

MolarMassAnalyser mma = new MolarMassAnalyser(gasStream);
double molarMass = mma.getMeasuredValue("kg/mol");  // g/mol = molarMass * 1000

WaterContentAnalyser

Measures water content in gas streams.

import neqsim.process.measurementdevice.WaterContentAnalyser;

WaterContentAnalyser wca = new WaterContentAnalyser(gasStream);
double waterContent = wca.getMeasuredValue("ppm");  // water content, ppm

pHProbe

Measures pH of aqueous streams.

import neqsim.process.measurementdevice.pHProbe;

pHProbe ph = new pHProbe(aqueousStream);
double phValue = ph.getMeasuredValue("");  // pH

Multi-Phase Measurement

MultiPhaseMeter

Simulates multi-phase flow meter measurements.

import neqsim.process.measurementdevice.MultiPhaseMeter;

MultiPhaseMeter mpm = new MultiPhaseMeter("MPFM-1", multiphaseStream);

double gasFlow = mpm.getGasFlowRate("Sm3/hr");
double oilFlow = mpm.getOilFlowRate("m3/hr");
double waterFlow = mpm.getWaterFlowRate("m3/hr");
double waterCut = mpm.getWaterCut();
double gor = mpm.getGOR("Sm3/Sm3");

Compressor Monitoring

CompressorMonitor

Monitors compressor performance parameters.

import neqsim.process.measurementdevice.CompressorMonitor;

CompressorMonitor cm = new CompressorMonitor(compressor);

double polyEff = cm.getPolytropicEfficiency();
double isenEff = cm.getIsentropicEfficiency();
double head = cm.getPolytropicHead("kJ/kg");
double power = cm.getPower("kW");
double surgeMargin = cm.getSurgeMargin();

Well Allocation

WellAllocator

Allocates production to individual wells based on test data.

import neqsim.process.measurementdevice.WellAllocator;

WellAllocator allocator = new WellAllocator("Allocation System");
allocator.addWellTest("Well-A", oilRate, gasRate, waterRate);
allocator.addWellTest("Well-B", oilRate2, gasRate2, waterRate2);
allocator.allocateProduction(totalOil, totalGas, totalWater);

double wellAOil = allocator.getAllocatedOil("Well-A");

Python Usage

from jpype import JClass

# Import measurement devices
CombustionEmissionsCalculator = JClass('neqsim.process.measurementdevice.CombustionEmissionsCalculator')
FlowInducedVibrationAnalyser = JClass('neqsim.process.measurementdevice.FlowInducedVibrationAnalyser')
NMVOCAnalyser = JClass('neqsim.process.measurementdevice.NMVOCAnalyser')

# Emissions calculation
emissions_calc = CombustionEmissionsCalculator("CO2", fuel_stream)
co2_rate = emissions_calc.getMeasuredValue("kg/hr")
print(f"CO2 emissions: {co2_rate} kg/hr")

# nmVOC analysis
nmvoc = NMVOCAnalyser("NMVOC", vent_stream)
nmvoc_rate = nmvoc.getMeasuredValue("tonnes/year")
print(f"NMVOC: {nmvoc_rate} tonnes/year")

# FIV analysis
fiv = FlowInducedVibrationAnalyser("FIV", pipeline)
fiv.setMethod("LOF")
lof = fiv.getMeasuredValue("")
print(f"LOF: {lof}")

API Reference

MeasurementDeviceBaseClass

Base class for all measurement devices.

Method Returns Description
getMeasuredValue() double Get measurement in default unit
getMeasuredValue(unit) double Get measurement in specified unit
setUnit(unit) void Set default measurement unit
getUnit() String Get current measurement unit
displayResult() void Display measurement result

StreamMeasurementDeviceBaseClass

Base class for stream-based measurement devices.

Method Returns Description
setStream(stream) void Set the stream to measure
getStream() StreamInterface Get the measured stream

CombustionEmissionsCalculator

Method Returns Description
getMeasuredValue(unit) double Get CO2 emissions rate
setComponents() void Update component list from stream

FlowInducedVibrationAnalyser

Method Parameters Description
setMethod(method) "LOF" or "FRMS" Set analysis method
setSupportArrangement(type) "Stiff", "Medium stiff", "Medium", "Flexible" Set pipe support type
setSupportDistance(distance) meters Set support spacing
setSegment(segment) segment number Analyse specific pipe segment

NMVOCAnalyser

Method Returns Description
getMeasuredValue(unit) double Get nmVOC flow rate
getnmVOCFlowRate(unit) double Get nmVOC flow rate

See Also