Solid-sorbent fluidized-bed DAC with compression heat recovery — a COOLPROP process flowsheet
A second, lower-temperature DAC pathway alongside the liquid-KOH + rotary-kiln example: the captured CO₂ loads onto a solid sorbent, which regenerates in an indirectly-heated fluidized bed (real Wen-Yu minimum-fluidization sizing + Arrhenius desorption kinetics, the FluidizedBed) at 120 degC — the real low-temperature regime solid amine/physisorbent DAC sorbents actually use, versus the other example's ~977 degC calcination. The bed is fluidized by a recycled CO₂ sweep (self-sweep with product gas, a real design choice that sidesteps needing a steam-condensate knockout step). The desorbed CO₂ is compressed toward liquefaction pressure in one adiabatic stage — hot enough (~780 K discharge) that routing it through a heat exchanger against process utility water genuinely converts that water from subcooled liquid to a boiling mixed-phase stream before the CO₂ continues on to the same real liquefaction physics as the other DAC example.
Modeling assumptions & limitations
- 1This recovers real compression waste heat into a genuinely useful utility stream (the actual mechanical-vapor-recompression principle — reusing a compressor's own heat instead of rejecting it to cooling water) but does NOT feed that heat back into the fluidized bed's own desorption duty, which this unit op takes as a fixed wall-temperature parameter, not a second heating-utility stream — a literal closed MVR loop onto the desorber itself isn't wireable with this unit op as built.
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- Rigorous COOLPROP thermodynamics, solved by the same engine every simulation runs on.
- 5 unit operations modeled: 2× CO2 Compressor, Contactor, Desorber, HEAT Recovery HX, CO2 Refrigerant.
- Focus areas: Direct air capture, Fluidized bed, Heat recovery, CO2 liquefaction.
- Verified fast convergence — a real, measured solve time, not an estimate.
- Thermodynamics
- COOLPROP
- Components
- n2, oxygen, co2, water, loaded_sorbent, regenerated_sorbent
- Unit operations
- 2× CO2 CompressorContactorDesorberHEAT Recovery HXCO2 Refrigerant
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("fluidized-bed-dac-heat-recovery")
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
Direct air capture with solid-sorbent calcination + CO2 liquefaction
A Carbon Engineering-style DAC train: a fan draws ambient air (400 ppm CO₂) through a liquid-KOH contactor (a fixed-recovery separator — the same simplification the existing carbon-capture example uses for chemical absorption, since no CO₂-KOH electrolyte package exists) capturing ~75% of the CO₂. The captured CO₂ is causticized and precipitated into CaCO₃ pellets by the real (unmodeled-in-detail) KOH/Ca(OH)2 loop — represented here as a matched pellet feed sized to the captured CO₂ rate, since the generic reactor unit op can't itself produce a solid product (only a rotary kiln's decomposition path can, which is exactly what's used next). Those pellets calcine at ~977 degC in an indirectly-heated rotary kiln (real Arrhenius decomposition kinetics, Sullivan-Maynard-Valentine residence time), releasing pure CO₂ that's compressed to ~20 atm and chilled to 250 K — above the real Span-Wagner CO₂ saturation pressure at that temperature, so the solved outlet stream is genuine subcooled LIQUID CO₂ (not just dense-phase pipeline gas) — while the CaO leaves for slaking and reuse (the lime side of the closed loop, out of scope for the same reason as the causticization step). Run the Carbon Footprint report on this example for the real Scope 1/2/3 CO2e + carbon-tax liability breakdown already built into MaximaLabs's report generator.
Desiccant rotor HVAC — three-stage low-grade heat recovery
A desiccant dehumidification rotor whose regeneration air is preheated by three low-grade heat sources in ascending temperature order: a PVT (photovoltaic-thermal) collector loop at 40 °C, condenser heat rejected by the chiller at 50 °C, and a district-heating return at 55 °C. Cascading them warmest-last is the whole point — each coil lifts the air as far as its own source can reach, so the 55 °C district return is spent only on the final lift instead of being wasted on air that is still at ambient. Every coil leaves a 5 K approach at its hot end, which is what makes this solvable: a cold stream can never leave an exchanger hotter than the hot stream entering it, and in a series train each coil's outlet is the next one's inlet, so a target that looks reasonable in isolation becomes impossible two units downstream. The hot-side flows are sized so the water gives up its duty over a modest ΔT and stays above the air at the cold end as well — specifying the approach alone is not enough if the heat-capacity flow rates don't support it. The rotor's two halves are custom_block equation blocks (the regen side and the process side), and the process air is finished to a 16 °C supply condition by the evaporator coil.
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.
High-CO2 LNG with amine capture and CO2 reinjection
One 5.3 Mtpa LNG train on a reservoir whose gas is 14 mol% CO₂, where the CO₂ is not vented but compressed to dense phase and injected — 2.8 Mtpa of it, at 200 bar, which is the scale that makes this a storage project rather than a gesture. Two things make this different from every other LNG example here. First, the acid-gas removal is real chemistry, in the same flowsheet as the cryogenics: per-node thermo_overrides run the absorber, the rich/lean loop and the stripper on the 'enrtl-mdea-pz' electrolyte package (MDEA protonation + piperazine carbamate/dicarbamate speciation) while the gas train and the cold end run Peng-Robinson — the amine unit and the MCHE are not two models bolted together, they are one solve. Second, the CO₂ goes somewhere: the stripper overhead is knocked back, two-stage compressed with interstage cooling and drying, and pumped to 200 bar as a ~96 mol% dense-phase stream ready for a reinjection well, rather than leaving as a vent. The sweet gas is water-washed, dried and liquefied in the C3MR cold end to LNG at ~116 K.
Post-combustion CO₂ capture
A separator recovers 90% of the CO₂ from a flue-gas stream — the sustainability layer then tracks the captured tonnes.
CO₂ capture + compression
Post-combustion capture recovers 90% of the flue CO₂, then a compressor and after-cooler condition it to pipeline pressure for storage/EOR — the real energy cost after capture.