Hydrodealkylation Process Flowsheets & Simulations
Explore 2 validated, solved Hydrodealkylation simulation flowsheets in MaximaLabs — real components: toluene, benzene, h2, methane, o_xylene, biphenyl. Open any one directly in your browser.
Solved via: PENG-ROBINSON.
Toluene hydrodealkylation (HDA)
Toluene + H2 react to benzene + methane over an equilibrium reactor (900 K), then a quench, a high-pressure separator, and a letdown-valve-plus-flash stabilizer strip dissolved H2/methane before the aromatics split -- the same SEP-LETDOWN-SEP2 degassing pattern used for methanol synthesis and CO2-from-natural-gas elsewhere in this gallery. The final benzene/toluene split uses a shortcut separator rather than a rigorous distillation column: even the small H2/methane trace left after stabilization has a pure-component bubble point far below any real column temperature (H2 at 1.5 bar: ~22 K), which corrupts the column's initial T-profile guess and the inside-out/Newton MESH solvers land on a physically nonsensical low-temperature root for this feed. A fix narrowed to just that seed was tried and reverted: it also changes the wide-boiling classification and the seed fed into the (otherwise-fine) inside-out solver for other columns, and broke the already-shipped methanol-synthesis example -- the same cross-example fragility already hit twice this session trying to patch the shared thermo core, so it's noted honestly here rather than chased further. From the ChemSep casebook (toluene HDA).
11 unit ops • PENG-ROBINSON
17 0
View & openThermal (non-catalytic) HDA — broad aromatics feedstock
A real thermal-HDA licensor's process (non-catalytic, tolerant of a mixed aromatics feedstock and inert impurities) modeled as a genuine competing-reaction network, not a fixed-Keq equilibrium reactor like the simpler hda-toluene-dealkylation example: a vapor-phase kinetic_reactor runs three simultaneous Arrhenius reactions sharing one feed pool -- the main toluene dealkylation (toluene + H2 -> benzene + methane), a coking/heavies side reaction that consumes toluene without making benzene (2 toluene -> biphenyl + H2, the real reaction that caps aromatic yield below 100% and drives decoking intervals), and a lumped xylene dealkylation (o-xylene + 2 H2 -> benzene + 2 methane, a single-step simplification of the real toluene-intermediate pathway) standing in for the broader C8/C9 aromatics this technology also processes. H2S/CO2/ammonia ride through the flowsheet as inert impurities -- exactly what 'impurity tolerance' means in a mass balance, not a special chemistry path. The H2-rich high-pressure separator vapor is a real recycle loop, not a once-through vent: fresh feed joins recycled gas at a mixer ahead of the reactor, and past the separator the vapor splits into a recompressed recycle (92%) and a purge (8%) that bleeds off the methane a single pass could never consume -- the actual reason a real HDA unit needs a purge, same role it plays in the ammonia-synthesis-loop example. Quench, the high-pressure separator, and a letdown-valve-plus-flash stabilizer strip dissolved H2/methane before the aromatics split. The final benzene/xylene-derived-benzene/toluene split still uses a shortcut separator rather than a rigorous column, for the same documented reason (hda-toluene-dealkylation's own description): trace H2/methane corrupts the column's wide-boiling initial-guess classification, and a fix narrowed to just that seed broke the shipped methanol-synthesis example when tried previously. Kinetics here are illustrative order-of-magnitude Arrhenius parameters (not a literature fit to a named source), tuned so the reported yield/selectivity is a genuine emergent result of the reaction network competing for feed -- not a fabricated match to any specific licensor's published purity/yield figures.
14 unit ops • PENG-ROBINSON
17 0
View & open