What is the leanest stream to sustain a nonadiabatic loop reactor: Analysis and methane combustion experiments

TY - JOUR

T1 - What is the leanest stream to sustain a nonadiabatic loop reactor

T2 - Analysis and methane combustion experiments

AU - Madai, Aharon Y.

AU - Nekhamkina, Olga

AU - Sheintuch, Moshe

N1 - Publisher Copyright: © 2016 American Institute of Chemical Engineers

PY - 2017/6

Y1 - 2017/6

N2 - While previous studies experimentally demonstrated that loop reactor (LR) can be sustained with a lean feed (using ethylene combustion) and have analyzed the single-reaction adiabatic case, this work analyzes the effects of heat loss and of reactor size to determine the leanest stream (expressed in terms of adiabatic temperature rise ΔTlim) that will sustain the operation. For an adiabatic infinitely long reactor ΔTlim→0 while for a finite reactor ΔTlim scales as (1 + Pe/4)−1 where Pe = Luρcpf/k, and heat loss increases this limit by (β/Pe)1/2. Thus, a good design of a LR will aim to decrease conductivity (k) and radial heat-transfer coefficient (β) while increasing throughput (u) and reactor length. This article is also the first experimental demonstration of auto-thermal operation in a LR for catalytic abatement of low-concentration of methane, showing the leanest stream to be of 8000 ppm vs. 33,000 ppm in a once-through reactor. Experimental combustion results of methane and of ethylene are compared with model predictions.

AB - While previous studies experimentally demonstrated that loop reactor (LR) can be sustained with a lean feed (using ethylene combustion) and have analyzed the single-reaction adiabatic case, this work analyzes the effects of heat loss and of reactor size to determine the leanest stream (expressed in terms of adiabatic temperature rise ΔTlim) that will sustain the operation. For an adiabatic infinitely long reactor ΔTlim→0 while for a finite reactor ΔTlim scales as (1 + Pe/4)−1 where Pe = Luρcpf/k, and heat loss increases this limit by (β/Pe)1/2. Thus, a good design of a LR will aim to decrease conductivity (k) and radial heat-transfer coefficient (β) while increasing throughput (u) and reactor length. This article is also the first experimental demonstration of auto-thermal operation in a LR for catalytic abatement of low-concentration of methane, showing the leanest stream to be of 8000 ppm vs. 33,000 ppm in a once-through reactor. Experimental combustion results of methane and of ethylene are compared with model predictions.

KW - authothermal reactor

KW - catalytic reactors

KW - forced unsteady-state operation

KW - front propagation

KW - loop reactor

KW - methane combustion

UR - http://www.scopus.com/inward/record.url?scp=85018976695&partnerID=8YFLogxK

U2 - 10.1002/aic.15580

DO - 10.1002/aic.15580

M3 - 文章

AN - SCOPUS:85018976695

SN - 0001-1541

VL - 63

SP - 2030

EP - 2042

JO - AICHE Journal

JF - AICHE Journal

IS - 6

ER -