577
installation cost than adiabatic reactors. Owing to low-temperature range of
240–260 °C for increasing reaction rates and selectivity in isothermal reactors, these
reactors have limited applications. Various industries like Mitsubishi Heavy
Industries, Linde, Lurgi, and Haldor Topsoe are using these shell- and tube-type
reactors with higher recycle ratio and lower catalyst volume due to ease of operation [10].
3.1.1 Adiabatic Reactors: On the Basis of Design, These Adiabatic
Reactors Are Generally Classified in Two Types
Quench Reactors
A fraction of feedstock is heated before being fed upstream of the reactor. The fed
reactants react with the catalyst surface, and conversion of these reactants increase
the temperature of the process stream due to exothermic nature of the reaction.
Remaining feedstock along with catalyst fed cold in the reactor, which decreases the
temperature and increases the methanol yield. Despite the ease of process, this
scheme leads to non-uniform utilization of catalyst volume as upstream reacts with
higher catalyst volume as compared to the downstream. Haldor Topsoe’s multiple
bed reactor is a quench-type reactor.
Indirect Cooled Reactors
Adiabatic reactors are displaced in series with cooling devices connected between
the reactors. The reaction temperature is lowered due to these coolers and, thus,
enhanced per pass conversion and selectivity of methanol. As the complete feedstock directly enters into the reactor, it reduces the utilized catalyst volume than
quench-type reactors.
Examples of such reactors are (1) Kellog, Brown, and Root’s adiabatic reactors
and (2) Toyo Engineering Corporation’s MRF-Z reactors.
3.2 Liquid Phase Reactors
Single pass conversion in fixed bed reactors is limited owing to equilibrium nature
of this methanol synthesis reaction. Significant recycling of unreacted synthesis gas
can diminish this conversion limitation which is the main problem associated with
conventional fixed bed reactors. Many studies have been carried out in reactor
design to improve the methanol productivity for gas phase using multifunctional
reactor systems (coupling of exothermic and endothermic reaction systems for better heat utilization) and shell-tube-type heat exchangers. However, these reactors
also have some limitations like pressure drops, hot spots formation during reaction
Perspectives in Carbon Oxides Conversion to Methanol/Dimethyl Ether: Distinctive…
installation cost than adiabatic reactors. Owing to low-temperature range of
240–260 °C for increasing reaction rates and selectivity in isothermal reactors, these
reactors have limited applications. Various industries like Mitsubishi Heavy
Industries, Linde, Lurgi, and Haldor Topsoe are using these shell- and tube-type
reactors with higher recycle ratio and lower catalyst volume due to ease of operation [10].
3.1.1 Adiabatic Reactors: On the Basis of Design, These Adiabatic
Reactors Are Generally Classified in Two Types
Quench Reactors
A fraction of feedstock is heated before being fed upstream of the reactor. The fed
reactants react with the catalyst surface, and conversion of these reactants increase
the temperature of the process stream due to exothermic nature of the reaction.
Remaining feedstock along with catalyst fed cold in the reactor, which decreases the
temperature and increases the methanol yield. Despite the ease of process, this
scheme leads to non-uniform utilization of catalyst volume as upstream reacts with
higher catalyst volume as compared to the downstream. Haldor Topsoe’s multiple
bed reactor is a quench-type reactor.
Indirect Cooled Reactors
Adiabatic reactors are displaced in series with cooling devices connected between
the reactors. The reaction temperature is lowered due to these coolers and, thus,
enhanced per pass conversion and selectivity of methanol. As the complete feedstock directly enters into the reactor, it reduces the utilized catalyst volume than
quench-type reactors.
Examples of such reactors are (1) Kellog, Brown, and Root’s adiabatic reactors
and (2) Toyo Engineering Corporation’s MRF-Z reactors.
3.2 Liquid Phase Reactors
Single pass conversion in fixed bed reactors is limited owing to equilibrium nature
of this methanol synthesis reaction. Significant recycling of unreacted synthesis gas
can diminish this conversion limitation which is the main problem associated with
conventional fixed bed reactors. Many studies have been carried out in reactor
design to improve the methanol productivity for gas phase using multifunctional
reactor systems (coupling of exothermic and endothermic reaction systems for better heat utilization) and shell-tube-type heat exchangers. However, these reactors
also have some limitations like pressure drops, hot spots formation during reaction
Perspectives in Carbon Oxides Conversion to Methanol/Dimethyl Ether: Distinctive…