NeqSim’s filter equipment represents particulate filters, coalescers, strainers, and granular-media beds as two-port process units. The default is a fixed clean differential pressure. Optional models add flow-dependent hydraulics, particle-size efficiency, loading and breakthrough, bypass, backwash or regeneration, and preliminary vessel design.

Contents

Classes and scope

The main classes are in neqsim.process.equipment.filter.

Class Purpose
Filter Generic particulate, coalescer, strainer, or media-filter unit
CharCoalFilter Compatibility class that selects activated-carbon media defaults
SulfurFilter Detects and captures a configurable fraction of solid elemental sulfur (S8)
FilterPerformanceCurve Particle size versus beta-ratio test data
FilterPressureDropCurve Actual volumetric flow versus clean differential-pressure data

The generic concentration model is an external solids or aerosol inventory. It reports contaminant capture but does not remove a thermodynamic component from the outlet fluid. Use contaminant-specific equipment when molecular removal must be included in the stream material balance.

Verified quick start

This complete Java 8 example creates a gas stream, configures a cartridge filter from beta-ratio data, calculates steady-state performance and preliminary mechanical design, and then advances the dynamic loading state.

import java.util.List;
import java.util.UUID;
import neqsim.process.equipment.filter.Filter;
import neqsim.process.equipment.filter.FilterPerformanceCurve;
import neqsim.process.equipment.filter.FilterType;
import neqsim.process.equipment.stream.Stream;
import neqsim.process.equipment.stream.StreamInterface;
import neqsim.process.mechanicaldesign.filter.FilterMechanicalDesign;
import neqsim.thermo.system.SystemInterface;
import neqsim.thermo.system.SystemSrkEos;

public final class FilterQuickStart {
  private FilterQuickStart() {}

  public static void main(String[] args) {
    SystemInterface fluid = new SystemSrkEos(298.15, 20.0);
    fluid.addComponent("methane", 1.0);
    fluid.setMixingRule("classic");

    Stream feed = new Stream("filter feed", fluid);
    feed.setFlowRate(1000.0, "kg/hr");
    feed.run();

    FilterPerformanceCurve curve = new FilterPerformanceCurve(
        new double[] { 5.0, 10.0, 20.0 },
        new double[] { 2.0, 100.0, 1000.0 });
    curve.setTestStandard("ISO 16889:2022");

    Filter filter = new Filter("inlet cartridge filter", feed);
    filter.setFilterServiceType(FilterType.CARTRIDGE);
    filter.setDeltaP(0.10); // bar
    filter.setPerformanceCurve(curve);
    filter.setParticleSize(10.0); // micrometres
    filter.setInletParticleConcentration(100.0); // mg/kg
    filter.setTerminalDeltaP(1.0); // bar
    filter.setElementCollapsePressure(5.0); // bar
    filter.setElementIntegrityVerified(true);
    filter.run();

    StreamInterface cleanGas = filter.getOutletStream();
    double efficiency = filter.getCurrentRemovalEfficiency();
    double outletConcentration = filter.getOutletParticleConcentration(); // mg/kg
    double capturedRate = filter.getCalculatedCapturedRate(); // kg/hr

    FilterMechanicalDesign design =
        (FilterMechanicalDesign) filter.getMechanicalDesign();
    design.setMaxOperationPressure(70.0); // bara
    design.setMaxOperationTemperature(333.15); // K
    design.calcDesign();

    int elements = design.getRequiredElements();
    double vesselId = design.getInnerDiameter(); // m
    List<String> warnings = design.getDesignWarnings();

    filter.setLoadingCapacity(2.0); // kg
    filter.setPressureDropIncreaseAtCapacity(0.5); // bar
    filter.setCalculateSteadyState(false);
    filter.runTransient(3600.0, UUID.randomUUID());

    System.out.printf(
        "Pout=%.3f bara, efficiency=%.4f, Cout=%.3f mg/kg, "
            + "captured=%.6f kg/hr, elements=%d, ID=%.3f m, "
            + "loading=%.6f kg, warnings=%d%n",
        cleanGas.getPressure("bara"), efficiency, outletConcentration,
        capturedRate, elements, vesselId, filter.getSolidsLoading(),
        warnings.size());
  }
}

At the stated beta ratio, the nominal removal efficiency is 0.99 and the reported outlet concentration is 1 mg/kg. The first transient hour adds the calculated captured mass to solidsLoading. The component composition and enthalpy of cleanGas are unchanged apart from the pressure-flash response.

Filter types

setFilterServiceType(...) selects construction-specific hydraulic and design defaults. Replace these screening defaults with project or vendor data.

FilterType Typical service Default clean-pressure-drop model
CARTRIDGE Gas or liquid particulate removal Flow-scaled
BAG Produced water and liquid filtration Flow-scaled
Y_STRAINER Compact coarse protection Flow-scaled, quadratic
BASKET_STRAINER Coarse liquid protection Flow-scaled, quadratic
COALESCER Aerosol or dispersed-droplet capture Flow-scaled, quadratic
GRANULAR_MEDIA Sand, nutshell, or guard media Ergun
BACKWASHABLE_MEDIA Regenerable produced-water media Ergun
ACTIVATED_CARBON Activated-carbon guard bed Ergun

Particle and droplet capture

For particles at or above size $x$, the beta ratio and fractional efficiency are

\[\beta_x = \frac{N_{\mathrm{upstream},x}} {N_{\mathrm{downstream},x}}\] \[\eta_x = 1 - \frac{1}{\beta_x}.\]

FilterPerformanceCurve uses log-linear interpolation between supplied beta ratios and clamps to the nearest endpoint outside the tested particle-size range. setParticleSize(...) takes micrometres. setInletParticleConcentration(...) takes mg/kg of process fluid. After run(), getOutletParticleConcentration() reports mg/kg and getCalculatedCapturedRate() reports kg/hr.

Loading is accumulated only by runTransient(...) when steady-state mode is disabled. A steady-state run() calculates the capture rate but does not change the accumulated loading state.

Pressure-drop models

Actual volumetric flow is evaluated at the filter inlet.

Model Relation Required data
FIXED Constant clean differential pressure setDeltaP(...)
FLOW_SCALED $\Delta P=\Delta P_{ref}(Q/Q_{ref})^n$ Clean differential pressure, reference actual flow, exponent
TABULATED Linear interpolation; defined endpoint extrapolation FilterPressureDropCurve
ERGUN Viscous and inertial packed-bed terms Area, depth, media diameter, void fraction

Use setReferenceFlowRate(...) in actual m3/hr for the flow-scaled model. Installing a FilterPressureDropCurve selects the tabulated model. Use setMediaGeometry(areaM2, bedDepthM, particleDiameterM, voidFraction) for the Ergun model. NeqSim obtains density and viscosity from the inlet thermodynamic state, so phase, pressure, and temperature affect the result.

The Ergun implementation is a homogeneous packed-bed screening model. It does not represent channeling, distributor maldistribution, non-spherical-particle corrections, bed compaction, or multiphase flow through the media.

Dynamic loading and maintenance

Dynamic operation requires setCalculateSteadyState(false) followed by runTransient(dtSeconds, calculationId). The generic state includes:

setSolidsLoadingRate(...) supplies a measured captured rate and disables the concentration-based rate. Alternatively, particle concentration and removal efficiency determine the captured rate automatically. startBackwash() and startRegeneration() activate their configured removal rates during transient steps. Stop them explicitly, or call resetDynamicState() after element replacement or completed maintenance.

The loading pressure contribution is

\[\Delta P = \Delta P_{\mathrm{clean}} + \Delta P_{\mathrm{capacity}} f_{\mathrm{loading}}.\]

Breakthrough is zero up to breakthroughStartFraction and increases linearly to one at a loading fraction of one. Loading may exceed the nominal capacity; use isReplacementRequired() as an operating signal rather than assuming the state is capped.

Differential-pressure bypass

setBypassCrackingDeltaP(...) enables a parallel-path screening calculation. When unrestricted differential pressure exceeds the cracking setting, the applied pressure drop is capped and getBypassFraction() reports the estimated unfiltered fraction. Bypassed flow reduces the current removal efficiency.

The model assumes a quadratic parallel bypass path. Use explicit splitter, valve, recycle, and control equipment when the bypass network or valve characteristic matters.

Mechanical design

Filter constructs a FilterMechanicalDesign with the equipment. After the process calculation, calcDesign() performs preliminary:

Maximum operating pressure is in bara and maximum operating temperature is in kelvin. The design class applies configurable pressure and temperature margins. The result is screening-level evidence, not a certified pressure-vessel or filter-element design.

Final design requires the governing code edition, project design rules, certified material allowables, weld efficiency, corrosion and erosion allowances, external loads, nozzle reinforcement, closure and support design, fatigue, fire and relief cases, materials compatibility, inspection strategy, and vendor review.

Specialized filters

CharCoalFilter selects ACTIVATED_CARBON defaults and inherits the generic Ergun, loading, and regeneration models. It does not remove a named molecular component. Use an adsorption bed for component adsorption.

SulfurFilter performs a solid-aware flash when S8 is present and captures the configured fraction of solid-phase S8. It removes that captured amount from the outlet thermodynamic inventory and adds the captured rate to dynamic loading during runTransient(...). The sulfur element capacity and installed element count define the inherited loading capacity. See the reactor guide for a complete SulfurOxidationReactor to SulfurFilter example.

For molecular removal, use the dedicated mercury guard-bed model, adsorption-bed model, or H2S scavenger, as applicable.

Standards basis

NeqSim stores user-supplied laboratory or vendor results and applies open, configurable calculations. It does not embed protected acceptance tables, certify equipment, or establish project compliance.

Reference Use in NeqSim
ISO 16889:2022 Record and interpolate supplied beta-ratio data
ISO 3968:2017 Record and interpolate supplied clean differential-pressure data
ISO 2942:2018 Record project or supplier evidence of element fabrication integrity
ISO 2941:2009 Compare calculated differential pressure with a user-supplied collapse or burst rating
ASME BPVC Section VIII, Division 1 Basis for preliminary shell and head membrane-thickness equations

Confirm that a cited edition and method apply to the fluid, element, and project. The ISO references above are primarily hydraulic-fluid filter test methods; gas coalescers and special media may require different vendor or project methods.