Mercury guard bed simulation

1 inlet -> 1 outlet (trace Hg removed; reports bed life)

Governing equations

The exact equations the solver works for a mercury guard bed — the same math shown in the app's "Theory" panel, not a black box.

$\dot m_{Hg}$

mercury captured [kg/s]

$\dot V_N$

gas rate on the normal-cubic-metre basis (0 C, 1 atm) [Nm^3/s]

$c_{in}$

inlet mercury concentration [ug/Nm^3]

$c_{out}$

outlet mercury (default 0.01 = the brazed-aluminium limit) [ug/Nm^3]

$t_{life}$

bed life before changeout [s]

$m_C$

installed carbon charge [kg]

$q_{Hg}$

carbon mercury capacity [kg Hg / kg carbon]

$\mu$

gas viscosity [Pa.s]

$\rho$

gas mass density [kg/m^3]

$\varepsilon$

bed voidage [-]

$d_p$

particle diameter [m]

$v$

superficial velocity [m/s]

$L$

bed height [m]

Parameters

non-regenerable sulfur-impregnated carbon guard bed protecting a brazed-aluminium cold box from liquid-metal embrittlement. Mercury is a PARAMETER ('inlet_mercury' [ug/Nm3]), not a thermo component -- at ppb it is meaningless to an EoS -- so the process stream passes through untouched and the Hg balance is tracked alongside. Set 'carbon_mass' [kg]; reports bed_life_years from the capacity balance, plus Ergun dP. Outlet defaults to the 0.01 ug/Nm3 brazed-aluminium spec. Capacity model, not breakthrough

Example flowsheets that use it