MaximaLabs

Cement, and the CO₂ that fuel switching cannot remove

Limestone calcined in a rotary kiln with real decomposition kinetics, and the released CO₂ compressed and cooled to a liquid.

Rotary kiln with real Arrhenius decomposition kineticsSullivan-Maynard-Valentine residence time, not a guessProcess CO₂ captured, not just combustion CO₂
Limestone
Rotary kiln
Calcined solids
Cooler
Knockout drum
Condensate
CO₂ compressor
Cooler
Liquefaction
Vent gas
Liquid CO₂

The actual dark-mode canvas: limestone calcined in an indirectly-heated rotary kiln releasing a CO₂-rich off-gas, which is knocked out, compressed and cooled until the CO₂ liquefies for transport.

The CO₂ that fuel switching cannot remove

Roughly two thirds of a cement plant's carbon comes out of the limestone itself, not the fuel — so no amount of renewable heat removes it and capture is the only route. The kiln here is sized on a real residence-time correlation with Arrhenius decomposition along its length, and the compression train that liquefies the resulting CO₂ is solved with it. Scope note: the off-gas is modelled dry, which the example's description states.

CaCO3CaO+CO2(ΔH>0, strongly endothermic)\mathrm{CaCO_3} \longrightarrow \mathrm{CaO} + \mathrm{CO_2} \quad (\Delta H > 0,\ \text{strongly endothermic})
k(T)=Aexp ⁣(Ea/RT)(plug-flow decomposition along the kiln)k(T) = A\exp\!\left(-E_a/RT\right) \quad \text{(plug-flow decomposition along the kiln)}
τ=0.19LNDtanβ(Sullivan-Maynard-Valentine residence time)\tau = \frac{0.19\,L}{N\,D\,\tan\beta} \quad \text{(Sullivan-Maynard-Valentine residence time)}

Unit ops shipped for this vertical

Rotary kiln

Indirect-fired shell with real Arrhenius decomposition kinetics and Sullivan-Maynard-Valentine residence time.

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Heater / cooler

Duty- or outlet-condition-specified energy-balance stage.

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Flash drum

Single-stage vapor-liquid equilibrium split at a fixed temperature/pressure.

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Compressor

Polytropic compression to pipeline/process pressure.

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Live plant integration

Stream kiln shell temperature, off-gas CO₂ purity and compressor discharge from the plant's OPC-UA server into this flowsheet's twin comparison — calcination completeness and capture energy move together, and the solved kiln ties them.

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Try it yourself

  • Rotary kiln with Arrhenius decomposition along its length
  • Sullivan-Maynard-Valentine residence time, not a guess
  • Process CO₂ captured, not only combustion CO₂

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