Wrong-way behavior of a catalytic packed-bed reactor

Thesis/Dissertation · Thu Dec 31 23:00:00 EST 1987

OSTI ID:7054792

Chen, Y C

A sudden decrease in the feed temperature or a sudden in the gas flowrate into a catalytic packed bed reactor may lead to a transient temperature rise, which is known as wrong-way behavior. The transient temperature rise is caused by the different travelling speeds of the concentration and temperature waves in the reactor. The unexpected temperature excursion may damage the catalyst, cause runaway of the reactor, ignite undesired side reactions and complicate the control strategy and shut-down procedures. Mathematical models with different degrees of simplification are used to investigate the behavior of the reactor when the feed temperature is suddenly decreased. Methanation of carbon dioxide on a nickel catalyst is used to study experimentally the wrong-way behavior when the gas flowrate is suddenly increased. Initially, a first-order exothermic reaction is studied with a one-dimensional heterogeneous dispersion model. The interfacial and intraparticle heat and mass transfer resistance may lead to a higher transient temperature rise than that predicted from a homogeneous model. The wrong-way behavior for two parallel reactions and two consecutive reactions are studied separately using a pseudo-homogeneous plug-flow model and a pseudo-homogeneous dispersion model. The experiment using the methanation of carbon dioxide on a nickel catalyst shows that a wrong-way behavior can occur when the gas flowrate is suddenly increased. Only a single steady state exists for 3% carbon dioxide in this study. The maximum transient temperature rise increases with the initial conversion.

• Research Organization: Houston Univ., TX (USA)
• OSTI ID: 7054792
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010408* -- Coal
Lignite
& Peat-- C1 Processes-- (1987-)
ACTIVATION ENERGY
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMICAL REACTORS
CONTROL
DAMAGE
ELEMENTS
ENERGY
ENERGY TRANSFER
FLOW RATE
FLUID FLOW
GAS FLOW
HEAT TRANSFER
HYDROGENATION
IGNITION
KINETICS
MASS TRANSFER
MATHEMATICAL MODELS
METALS
METHANATION
NICKEL
OXIDES
OXYGEN COMPOUNDS
PROCESS CONTROL
QUANTITY RATIO
REACTION KINETICS
STEADY-STATE CONDITIONS
TEMPERATURE DEPENDENCE
TEMPERATURE GRADIENTS
TRANSIENTS
TRANSITION ELEMENTS