Mol-sieve dehydrator simulation

1 inlet -> 1 dried outlet (reports cycle time + regen duty)

Governing equations

The exact equations the solver works for a mol-sieve dehydrator — the same math shown in the app's "Theory" panel, not a black box.

$q_{usable}$

design capacity after the unused-bed correction [kg H2O/kg sieve]

$q_{eq}$

equilibrium (isotherm) capacity [kg H2O/kg sieve]

$L_{MTZ}$

mass-transfer-zone length [m]

$L_{bed}$

bed height [m]

$t_{cycle}$

adsorption time before changeover [s]

$m_{sieve}$

sieve charge per bed [kg]

$\dot m_{H_2O}$

water removed [kg/s]

$y_{out}$

outlet water mole fraction (1e-7 = 0.1 ppmv, the cryogenic spec) [-]

$Q_{regen}$

regeneration duty [W]

$\Delta h_{des}$

heat of desorption, water from 4A (1800 Btu/lb = 4.187 MJ/kg) [J/kg]

$c_{p,s}$

sieve heat capacity [J/kg/K]

$c_{p,steel}$

vessel steel cp [J/kg/K]

$m_{vessel}$

vessel steel mass [kg]

$\Delta T$

regeneration temperature rise [K]

Parameters

4A molecular-sieve bed drying gas to the cryogenic <=0.1 ppmv water spec a cold box needs (TEG cannot reach it). Set 'sieve_mass' [kg]; reports cycle_time from the water balance with a length-of-unused-bed correction on the equilibrium capacity, plus regeneration_duty (heat of desorption defaults to the GPSA 1800 Btu/lb figure) and Ergun dP. Equilibrium/capacity design model, not a dynamic breakthrough simulation

Example flowsheets that use it