Flue-gas desulfurization: venturi wet scrubber — a PENG-ROBINSON process flowsheet
A coal/oil-fired power-plant stack gas (SO₂ in a hot N₂/CO₂/O₂/water flue) is cleaned in a high-energy venturi wet scrubber before the stack — the classic flue-gas-desulfurization (FGD) front end. The new venturi_scrubber unit op accelerates the gas through a throat where injected scrubbing water is atomized, and a stated fraction of the soluble SO₂ is absorbed into the drops and carried out as a slurry while the cleaned gas goes up the stack. Two cited pieces are computed: the momentum-exchange pressure drop ΔP = ρ_L·(Q_L/Q_G)·v_gt² (Calvert 1968; de Nevers — the L/G here is ~1.4 L/m³ and the throat runs 90 m/s, giving ~11 kPa, a real high-energy venturi), and the SO₂ removal (92% at this water rate) that drops the stack SO₂ to a fraction of the inlet.
Modeling assumptions & limitations
- 1The gas absorption is a stated removal efficiency (a screening scrub — the rate-based reactive contactor with real liquid-phase alkali chemistry is the absorber / rate_based_absorber), the cut-diameter particulate physics is idle here (a gas-only feed), and ΔP assumes complete drop acceleration. A screening process-design starting point for scrubber sizing / pressure-drop budgeting, not a certified FGD performance deliverable.
258 views 0 forks
- Rigorous PENG-ROBINSON thermodynamics, solved by the same engine every simulation runs on.
- 1 unit operations modeled: VS.
- Focus areas: Air pollution control, Flue-gas desulfurization, Venturi scrubber, SO2 removal, Emissions.
- Verified fast convergence — a real, measured solve time, not an estimate.
- Thermodynamics
- PENG-ROBINSON
- Components
- nitrogen, carbon_dioxide, oxygen, water, sulfur_dioxide
- Unit operations
- VS
Opens in a new tab, loaded straight into the app — no setup.
Read the step-by-step guideReproduce this exact result from Python — the real client.get_example() → run_and_wait() path, not a mockup.
from flowsim.sdk import FlowSimClient
client = FlowSimClient()
example = client.get_example("flue-gas-desulfurization-venturi")
sim = client.create_simulation(example["title"], example["flowsheet"])
result = client.run_and_wait(sim["id"])
print(result["status"]) # "converged"
streams = client.streams(sim["id"])Related models
Sour-gas sweetening — six-category footprint
A fuel-fired feed-gas heater, acid-gas removal, and a VOC purge — vented to atmosphere — so the Sustainability panel shows all six impact categories at once: carbon, water, acidification (vented H₂S/NH₃ + combustion NOx), eutrophication (NH₃ + NOx), photochemical ozone (vented benzene) and cumulative energy demand. Illustrative screening vent compositions — a real plant Claus/incinerates the H₂S and controls the VOC rather than venting; the point is to exercise the multi-category footprint on a process that genuinely carries these species. Spec-based separators, so it converges fast and conserves mass.
Thermal oxidizer: VOC-laden waste-gas incineration
A dilute VOC-laden air stream preheats and combusts completely at typical thermal-oxidizer operating temperature (~1100 K / 827degC, in the 750-870degC range these units commonly run at for reliable VOC destruction), destroying toluene (a standard VOC surrogate) to CO₂ + H₂O (C₇H₈ + 9 O₂ → 7 CO₂ + 4 H₂O, exactly mass-balanced) at 99.9% destruction-and-removal efficiency (DRE) — the real regulatory benchmark figure widely cited for thermal oxidizers/incinerators (e.g. the hazardous-waste-incinerator DRE standard), not a fabricated number. This is generic combustion-based air-pollution-control technology, not Linde-proprietary IP — built the same way already models fuel-gas combustion, applied here to a waste-destruction duty instead of a process-heating duty.
Dust collector selection: cyclone vs ESP vs baghouse
The same kiln offgas — 500 mol/s at 420 K carrying 8 mol/s of 20 micron dust (sphericity 0.7, GSD 2.2) — offered to the three gas-cleaning devices side by side, because choosing between them is a real design decision and the three models answer different questions. The cyclone catches 85.6%. That number is not specified anywhere: it is computed from the particle size distribution against the device's own cut size, and its d50 lands at 10 microns — half the dust's mean size, so everything finer escapes. It is the honest ceiling of a device with no consumables and no electricity, and it costs the most fan power of the three here at 1555 Pa. The ESP reaches 99.81% by Deutsch-Anderson on the migration velocity and plate area — also predicted, not specified — at essentially no pressure drop. The baghouse reports 99.8%, and this one you should read differently: its capture is the penetration you gave it, an INPUT. The baghouse model predicts pressure drop (37.7 Pa here, from the Cooper & Alley filter-drag law) and cloth area (1149 m2 at a 0.015 m/s air-to-cloth ratio) — not efficiency. Two of these three efficiencies are predictions and one is a specification, and a comparison that hides which is which is worse than no comparison. Why three parallel trains and not one series train. A cyclone roughing into a baghouse polishing is the standard industrial arrangement, and it cannot be drawn here: the cyclone folds its escaped dust back into the gas stream without a solids payload, so a second collector downstream sees no solids to catch. That is a modelling limitation, not a physical one, and it is stated rather than designed around. Bounded: the ESP's zero pressure drop is a model simplification (a real precipitator runs a few hundred Pa), and the pressure drops here are screening values from published correlations, not vendor guarantees.
Phosphoric acid plant fluorine recovery: fluosilicic acid from two scrubbers
A wet-process phosphoric acid plant releases the phosphate rock's fluorine as gas in two places: the attack tank, as silicon tetrafluoride, and the vacuum concentrator, where the acid's fluosilicic acid breaks down to SiF₄ and HF about 1:2 (EPA AP-42 §8.9 puts 20-40% of the rock's fluorine into the concentrator vapour). Both streams are scrubbed with water to fluosilicic acid, H₂SiF₆, sold to make aluminium fluoride and cryolite, as EFMA/Fertilizers Europe BAT Booklet No. 4 (2000) §2.4 describes them. The fume scrubber takes the attack-tank gas of the wet-process-phosphoric-acid-dihydrate example (72.6 mol/s CO₂ and 1.50 mol/s SiF₄) through two absorbers in series at 90% each, the booklet's figure for one atmospheric absorber: 99.0% of the fluorine is removed, the booklet's 'better than 99%', and 1.14 g/s of fluorine leaves with the stack gas. With no HF in that gas the SiF₄ hydrolyses, 3 SiF₄ + 2 H₂O → 2 H₂SiF₆ + SiO₂, so a third of the silicon drops out as 107 kg/h of silica, and the acid leaves at the booklet's 22% H₂SiF₆, 2.33 t/h of it. The hot humid gas condenses 11.56 mol/s of water into the liquor on its way to 320 K, and the 128 kW reaction heat is part of the 678 kW the liquor cooler removes. The vacuum scrubber takes the concentrator vapour at 0.12 bar in a single stage at 85%, inside the booklet's 83-86% recovery for a vacuum system: SiF₄ + 2 HF → H₂SiF₆ uses all the SiF₄ with the HF, so no silica forms, and the acid leaves at 20% (the booklet's 17-23%), 7.72 t/h of it; 59.8 g/s of fluorine goes on with the water vapour to the barometric condenser. Representative inputs, labelled: the concentrator vapour (21 mol/s of fluorine, half the DH example's acid fluorine, with the 30 kg/s of water a 28 to 54% P₂O₅ concentration evaporates), the scrub water rates and the scrubber temperatures.
Industrial steam boiler with capacity control
A natural-gas-fired water-tube boiler raising 50 t/h of steam at 42 bar and 400 C, with its three circuits and its capacity control on one flowsheet. Fuel: methane at 3 bar to the windbox. Combustion air / flue gas: an FD fan and a regenerative air preheater feed the burner at 15% excess air; the flame (adiabatic, 2252 K) then gives up its heat to the radiant evaporator, the superheater, the economizer and the air preheater in turn, and leaves the stack at 377 K with 3.0% O₂ dry. Steam: deaerated feedwater is pumped to 48 bar, warmed in the economizer, boiled in the evaporator and separated in the drum; saturated steam is superheated to 672.2 K and 2% is blown down. Capacity control: a steam-flow controller (FIC, integral action) sets the firing rate to hold the steam demand, a ratio station keeps combustion air at 15% excess, and the drum-level balance makes feedwater equal steam plus blowdown. At design it fires 49.92 mol/s of fuel (40.0 MW LHV); the evaporator takes 25.3 MW, the economizer 7.7 MW and the superheater 5.7 MW, for a direct efficiency of 96.7% LHV / 87.1% HHV. The heat-transfer banks are rated by UA, so a change of load redistributes the heat instead of reproducing it: run the sensitivity (70-100% load) and the superheat falls from 673 K to 605 K at 70%. Property method: pr-steam, Peng-Robinson for the gas with IAPWS-95 steam tables for pure water; plain Peng-Robinson puts 18% too little heat in the superheater. Bounds: no radiation or casing loss (a real boiler loses 1-2%, so efficiency reads high, and more so at part load); no dissociation in the flame; the radiant section is a fixed-UA exchanger, which overstates its absorption at deep turndown; no attemperator; and level and ratio control are the steady-state balances, not dynamic loops.
Geothermal flash-steam power plant (~90 MW)
A single-flash geothermal power plant on the IAPWS steam tables. A liquid-dominated geothermal well arrives at 240 °C / 35 bar and flashes across a separator down to 8 bar: about 15% of the brine becomes saturated steam and the rest is reinjected. The steam drives a condensing turbine to a 10 kPa vacuum (82% isentropic, exhaust quality ~0.9 — a real wet-steam expansion), a water-cooled condenser drops it to ~46 °C condensate, and a hotwell pump lifts it for reinjection alongside the brine. It converges to 89.9 MW of turbine shaft power. The separator (flash) pressure is the plant's key design knob: the defaultSensitivity sweeps it, trading a larger steam fraction at low pressure against higher steam enthalpy at high pressure — the flash-pressure optimization every single-flash geothermal plant makes. It runs on the rigorous IAPWS-95 water properties (steam package), and the turbine tracks steam quality into the two-phase dome rather than assuming a dry expansion.