| name | neqsim-teg-dehydration-modeling |
| version | 0.1.0 |
| description | Build a validated, closed-loop TEG (triethylene glycol) gas dehydration plant in NeqSim, including absorber, flash drum, regeneration column, stripper, lean-TEG recycle, and still-vent emission classification. USE WHEN: a task needs a runnable NeqSim TEG dehydration flowsheet (water dew point, lean-TEG purity, NMVOC/methane/benzene still-vent emissions) rather than a screening-level water-content estimate. |
| last_verified | 2026-06-26 |
| requires | {"python_packages":["neqsim"],"java_packages":["neqsim"],"env":[],"network":[]} |
TEG Dehydration Modeling
Use this skill to build a complete, converging triethylene-glycol (TEG) gas
dehydration plant in NeqSim. It captures a validated flowsheet topology and the
non-obvious settings (CPA fluid setup, regeneration-column tolerances, recycle
priorities, condenser/preheat energy coupling, makeup calculator) needed for the
process to solve as a closed loop. It returns a ProcessSystem plus the key
streams an agent needs for water dew point, lean-TEG purity, and still-vent
emission classification.
This is a real NeqSim build, not a public correlation placeholder. For a quick
"is dehydration required?" triage without building a plant, use
neqsim-water-dewpoint-dehydration-screening instead.
When to Use
- When a user asks to model a TEG dehydration unit and read water dew point, lean
TEG purity, or regeneration still-vent emissions.
- When an agent needs a runnable TEG flowsheet to study stripping gas, reboiler
temperature, TEG circulation rate, or once-through vs recirculated stripping gas.
- When emissions (NMVOC, methane, benzene, CO2, water) from the regeneration
still vent must be quantified and classified for an environmental screening.
Inputs
The build_teg_plant(...) function is fully parameterized. Key inputs:
feed_fractions: list of mole fractions (or percentages) aligned with
GAS_COMPONENTS (nitrogen, CO2, methane, ... , benzene).feed_flow_MSm3_day: wet/dry feed gas flow rate in MSm3/day.feed_temp_C, feed_pressure_bara: feed gas conditions.absorber_pressure_bara, absorber_temp_C: contactor conditions.teg_flow_kg_hr, teg_feed_temp_C, lean_teg_purity: lean TEG circulation.flash_drum_pressure_bara, reboiler_temp_C, stripping_gas_Sm3_hr:
regeneration conditions.n_absorber_stages, stage_efficiency: absorber model resolution.water_mode: 'saturated' (water-saturate the feed) or 'specified'
(set an inlet water content in mol-ppm via water_content_ppm_mol).saturation_temp_C, saturation_pressure_bara: optional saturation TP setter.recirculate_stripping_gas: True builds a true closed-loop stripping-gas
recycle (split dried overhead, blower, heater) to cut still-vent emissions.
Outputs
build_teg_plant(...) returns (process, streams):
process: a NeqSim ProcessSystem ready to run.streams: a dict of handles — dehydratedGas, flashGas, stillVent,
leanTEGtoAbs, waterDewAnalyser, strippingGas, recircBlower.
Helper functions produce the engineering results:
comp_mass_flows_kg_hr(stream): per-component mass flow (kg/hr).teg_mass_fraction(stream): TEG weight percent of a stream.classify_emissions(stream): dict with NMVOC, methane, CO2, water,
TEG, benzene, and total mass flows (kg/hr).
Engineering Method
The flowsheet follows the standard TEG dehydration topology:
- Fluid —
SystemSrkCPAstatoil (CPA EOS) with setMixingRule(10) and
setMultiPhaseCheck(False). TEG is added last so the lean-TEG composition
maps to leanComp[-1] = lean_teg_purity and leanComp[-2] = 1 - lean_teg_purity.
- Feed conditioning — optional saturation TP setter +
StreamSaturatorUtil
(saturated mode) or an inlet water component (specified mode), then a heater to
absorber TP.
- Absorber —
SimpleTEGAbsorber with gas-in and lean-TEG solvent-in streams.
- Rich TEG let-down and pre-heat — HP flash valve, rich preheater,
lean/rich exchangers (
HeatExchanger with UA values), degassing separator,
fine filter, LP flash valve.
- Regeneration —
DistillationColumn (reboiler + condenser) with loosened
tolerances (temperature 5e-2, mass 2e-1, enthalpy 2e-1) so the glycol/water
split converges; stripping gas fed to the reboiler tray; WaterStripperColumn
for deep lean-TEG purity.
- Recycles — lean-TEG recycle (priority 200,
setDownstreamProperty('flow rate'))
closes the solvent loop; the internal stripping-gas recycle returns stripper
overhead to the reboiler. With recirculate_stripping_gas=True, a second
makeup recycle (priority 150) recirculates dried overhead as stripping gas.
- Makeup and energy coupling — a
Calculator sizes TEG makeup from TEG lost
in the dry gas, flash gas, still vent, and water draws; the rich preheater is
driven by the condenser energy stream:
richPreheat.setEnergyStream(column.getCondenser().getEnergyStream()).
- Run —
process.runAsThread() then thr.join(...) (worker thread avoids
blocking and tolerates the recycle iterations).
Python Usage Pattern
from teg_dehydration_modeling import (
DEFAULT_FEED,
build_teg_plant,
classify_emissions,
teg_mass_fraction,
)
process, streams = build_teg_plant(
feed_fractions=DEFAULT_FEED,
feed_flow_MSm3_day=4.65,
feed_temp_C=25.0,
feed_pressure_bara=70.0,
absorber_pressure_bara=85.0,
absorber_temp_C=35.0,
teg_flow_kg_hr=5500.0,
teg_feed_temp_C=48.5,
lean_teg_purity=0.97,
flash_drum_pressure_bara=4.8,
reboiler_temp_C=197.5,
stripping_gas_Sm3_hr=180.0,
n_absorber_stages=4,
stage_efficiency=0.7,
)
thr = process.runAsThread()
thr.join(300000)
water_dew_C = float(streams["waterDewAnalyser"].getMeasuredValue("C"))
lean_teg_wt = teg_mass_fraction(streams["leanTEGtoAbs"])
still_vent = classify_emissions(streams["stillVent"])
print(water_dew_C, lean_teg_wt, still_vent["NMVOC"])
Validation Checklist
Common Mistakes
| Symptom | Cause | Fix |
|---|
| Regeneration column will not converge | Default tolerances too tight for glycol/water split | Loosen setTemperatureTolerance(5e-2), setMassBalanceTolerance(2e-1), setEnthalpyBalanceTolerance(2e-1) |
| Lean TEG purity wrong / NaN | TEG not added last, or composition indices off | Add water then TEG last; set leanComp[-1]=purity, leanComp[-2]=1-purity |
| Lean-TEG loop never closes | Recycle priority/property not set | Lean TEG recycle priority 200 with setDownstreamProperty('flow rate') |
| Class not found | Wrong CPA class name | Use SystemSrkCPAstatoil (lowercase statoil) |
| Run blocks or stalls | Running inline instead of on a thread | Use process.runAsThread() + thr.join(timeout_ms) |
| TEG inventory drifts | No makeup | Add the Calculator makeup sized from TEG in dry gas, flash gas, still vent, water draws |
| Water balance looks ~1-2% open | Only counting still vent + regen water draw | Water removed from the gas leaves via still vent + regen water/HC draw + degassing flash gas; include the flash-gas water term and closure tightens to <0.1% |
Limitations
- Inputs and examples are public and synthetic; no proprietary plant data,
vendor glycol packages, or company emission factors are included.
- Emission classification is a component-bucketing of stream mass flows
(NMVOC/methane/benzene/CO2/water); it is not a regulatory emission inventory.
- The absorber uses
SimpleTEGAbsorber with stage efficiency, not a rate-based
contactor model; deep dew-point design needs validated review.
- Convergence depends on reasonable inputs; extreme TEG rates, stripping gas, or
reboiler temperatures may require tolerance or guess-temperature tuning.
Related NeqSim Functionality
neqsim.thermo.system.SystemSrkCPAstatoil — CPA equation of state for
glycol/water/hydrocarbon systems (reached via from neqsim import jneqsim).neqsim.process.equipment.absorber.SimpleTEGAbsorber,
neqsim.process.equipment.absorber.WaterStripperColumn — TEG contactor and stripper.neqsim.process.equipment.distillation.DistillationColumn — TEG regeneration column.neqsim.process.equipment.util.Recycle, Calculator — solvent/stripping-gas
recycles and TEG makeup sizing.neqsim.process.measurementdevice.WaterDewPointAnalyser — dry-gas water dew point.- For a screening-only water-content triage before building a plant, use the
neqsim-water-dewpoint-dehydration-screening community skill.
References
