Valve Equipment

Documentation for valve equipment in NeqSim process simulation.

Table of Contents

Overview

Location: neqsim.process.equipment.valve

Classes:

Mechanical Design: neqsim.process.mechanicaldesign.valve

Throttling Valve

Basic Usage

import neqsim.process.equipment.valve.ThrottlingValve;

ThrottlingValve valve = new ThrottlingValve("FV-100", inletStream);
valve.setOutletPressure(30.0, "bara");
valve.run();

// Joule-Thomson cooling
double Tin = inletStream.getTemperature("C");
double Tout = valve.getOutletStream().getTemperature("C");
double deltaT = Tout - Tin;

System.out.println("Temperature change: " + deltaT + " °C");

Isenthalpic Expansion

Throttling is isenthalpic (constant enthalpy):

double H_in = inletStream.getEnthalpy("J/mol");
double H_out = valve.getOutletStream().getEnthalpy("J/mol");
// H_in ≈ H_out (within numerical precision)

Valve Sizing

Flow Coefficient (Cv)

// Set Cv
valve.setCv(150.0, "US");  // US gallons/min at 1 psi ΔP
// Or
valve.setCv(150.0, "SI");  // m³/hr at 1 bar ΔP

// Get Cv at current conditions
double Cv = valve.getCv("US");

Valve Opening

// Set valve position
valve.setPercentValveOpening(50.0);  // 50% open

// Cv varies with opening (inherent characteristic)
valve.setValveCharacteristic("linear");
// or
valve.setValveCharacteristic("equal_percentage");
// or
valve.setValveCharacteristic("quick_opening");

Calculate Pressure Drop

// Given Cv and flow, calculate ΔP
valve.setCv(100.0, "US");
valve.setPercentValveOpening(75.0);
valve.run();

double Pin = inletStream.getPressure("bara");
double Pout = valve.getOutletStream().getPressure("bara");
double deltaP = Pin - Pout;

Valve Characteristics

Control valves have inherent flow characteristics that define how Cv varies with valve opening.

Available Characteristics

Characteristic Description Best Application
Linear Flow proportional to opening Constant ΔP systems, bypass valves
Equal Percentage Equal opening increments = equal % flow change Variable ΔP, most process control
Quick Opening Large flow change at small openings On/off service, safety applications
Modified Parabolic Compromise between linear and equal % General purpose

Setting Valve Characteristic

import neqsim.process.mechanicaldesign.valve.ValveMechanicalDesign;

ValveMechanicalDesign mechDesign = (ValveMechanicalDesign) valve.getMechanicalDesign();
mechDesign.setValveCharacterization("equal percentage");

Characteristic Curves

         │
   100%  │                    ●─── Quick Opening
         │               ●───●
   Flow  │          ●───●    ●── Linear
   (Cv)  │     ●───●        ●
         │ ●───●        ●───── Equal Percentage
         │●        ●───●
    0%   └────────────────────
         0%    Opening    100%

Sizing Standards

NeqSim supports multiple valve sizing standards for different applications.

Available Standards

Standard Code Description
Default default Simplified IEC 60534 for gas, standard for liquid
IEC 60534 IEC 60534 Full IEC 60534-2-1 implementation
Extended IEC 60534 full IEC 60534 with all correction factors
Prod Choke prod choke Production choke with discharge coefficient

Setting Sizing Standard

ValveMechanicalDesign mechDesign = (ValveMechanicalDesign) valve.getMechanicalDesign();
mechDesign.setValveSizingStandard("IEC 60534");

IEC 60534 Gas Sizing

For compressible fluids (gas/vapor):

\[K_v = \frac{Q}{N_9 \cdot P_1 \cdot Y} \sqrt{\frac{M \cdot T \cdot Z}{x}}\]

Where:

Choked Flow Detection

Flow becomes choked when: \(x \geq F_\gamma \cdot x_T\)

Where:

Mechanical Design

Complete mechanical design calculations are available for valve body sizing, weight estimation, and actuator requirements.

Accessing Mechanical Design

ValveMechanicalDesign mechDesign = (ValveMechanicalDesign) valve.getMechanicalDesign();
mechDesign.calcDesign();

Design Results

Property Method Unit
ANSI Pressure Class getAnsiPressureClass() -
Nominal Size getNominalSizeInches() inches
Face-to-Face getFaceToFace() mm
Body Wall Thickness getBodyWallThickness() mm
Design Pressure getDesignPressure() bara
Design Temperature getDesignTemperature() °C
Actuator Thrust getRequiredActuatorThrust() N
Actuator Weight getActuatorWeight() kg
Total Weight getWeightTotal() kg

Example: Full Mechanical Design

// Create and run valve
ThrottlingValve valve = new ThrottlingValve("PCV-101", gasStream);
valve.setOutletPressure(60.0, "bara");
valve.run();

// Calculate mechanical design
ValveMechanicalDesign mechDesign = (ValveMechanicalDesign) valve.getMechanicalDesign();
mechDesign.calcDesign();

// Print results
System.out.println("=== VALVE MECHANICAL DESIGN ===");
System.out.println("Cv: " + valve.getCv());
System.out.println("ANSI Class: " + mechDesign.getAnsiPressureClass());
System.out.println("Size: " + mechDesign.getNominalSizeInches() + " inches");
System.out.println("Face-to-Face: " + mechDesign.getFaceToFace() + " mm");
System.out.println("Wall Thickness: " + mechDesign.getBodyWallThickness() + " mm");
System.out.println("Total Weight: " + mechDesign.getWeightTotal() + " kg");
System.out.println("Actuator Thrust: " + mechDesign.getRequiredActuatorThrust() + " N");

Detailed Documentation

See Valve Mechanical Design for complete documentation including:

Critical Flow

For high pressure drops, flow becomes critical (choked).

// Check if flow is critical
boolean isCritical = valve.isCriticalFlow();

// Critical flow factor
double Cf = valve.getCriticalFlowFactor();

Safety Valve (PSV)

Basic Setup

import neqsim.process.equipment.valve.SafetyValve;

SafetyValve psv = new SafetyValve("PSV-100", vessel);
psv.setSetPressure(100.0, "barg");  // Set pressure
psv.setBlowdownPressure(10.0, "%"); // 10% blowdown
psv.run();

// Check if valve is open
boolean isOpen = psv.isOpen();
double relievingFlow = psv.getRelievingFlow("kg/hr");

Sizing

// Required relieving capacity
psv.setRequiredCapacity(10000.0, "kg/hr");

// Get required orifice area
double area = psv.getRequiredOrificeArea("cm2");

// Select API orifice
String orifice = psv.selectAPIorifice();  // e.g., "J", "K", "L"

Choke Valve

For wellhead and production applications:

import neqsim.process.equipment.valve.ChokeValve;

ChokeValve choke = new ChokeValve("Wellhead Choke", wellStream);
choke.setOutletPressure(50.0, "bara");
choke.run();

// Or specify bean size
choke.setBeanSize(32, "64ths");  // 32/64" = 0.5"
choke.run();

double Pout = choke.getOutletStream().getPressure("bara");

Dynamic Simulation

// Valve dynamics
valve.setCalculateSteadyState(false);

// Valve stroke time
valve.setStrokeTime(10.0);  // seconds for 0-100%

// Step change
valve.setPercentValveOpening(80.0);

for (double t = 0; t < 30; t += 0.1) {
    valve.runTransient();
    double opening = valve.getActualOpening();  // Lags setpoint
}

Example: Pressure Letdown Station

ProcessSystem process = new ProcessSystem();

// HP gas inlet
Stream hpGas = new Stream("HP Gas", gasFluid);
hpGas.setFlowRate(50000.0, "kg/hr");
hpGas.setTemperature(50.0, "C");
hpGas.setPressure(100.0, "bara");
process.add(hpGas);

// Stage 1: 100 -> 50 bar
ThrottlingValve pv1 = new ThrottlingValve("PV-100", hpGas);
pv1.setOutletPressure(50.0, "bara");
pv1.setCv(200.0, "US");
process.add(pv1);

// Heater (compensate JT cooling)
Heater heater = new Heater("E-100", pv1.getOutletStream());
heater.setOutTemperature(40.0, "C");
process.add(heater);

// Stage 2: 50 -> 10 bar
ThrottlingValve pv2 = new ThrottlingValve("PV-101", heater.getOutletStream());
pv2.setOutletPressure(10.0, "bara");
pv2.setCv(300.0, "US");
process.add(pv2);

process.run();

// JT effects
System.out.println("After PV-100: " + pv1.getOutletStream().getTemperature("C") + " °C");
System.out.println("After E-100: " + heater.getOutletStream().getTemperature("C") + " °C");
System.out.println("After PV-101: " + pv2.getOutletStream().getTemperature("C") + " °C");

Joule-Thomson Coefficient

For ideal gases, $\mu_{JT} = 0$. For real gases:

\[\mu_{JT} = \left(\frac{\partial T}{\partial P}\right)_H = \frac{1}{C_p}\left[T\left(\frac{\partial V}{\partial T}\right)_P - V\right]\] 
// Get JT coefficient
double muJT = inletStream.getJouleThomsonCoefficient();  // K/bar