Dual-type Methanol Research Articles

Development of Two Novel Processes for Hydrogenation of CO2 to Methanol over Cu/ZnO/Al2O3 Catalyst to Improve the Performance of Conventional Dual Type Methanol Synthesis Reactor

Conventional methanol synthesis process (CR configuration) consists of water-cooled and gas-cooled reactors in which methanol and water are condensed inside the gas-cooled reactor which deactivates the catalyst. In this study, two novel configurations (AW and ACW configurations) are represented to address this problem in which the gas-cooled reactor is replaced with adiabatic reactor. Moreover, a condenser is applied between adiabatic and water-cooled reactors in ACW configuration. Results show that temperature increases somewhat along the adiabatic reactor that prevents gas condensate formation. Besides, the adiabatic reactor maximum temperature is less than that of first reactor in CR configuration which prevents copper based catalyst thermal sintering. Moreover, a high cross section-to-length ratio of the adiabatic reactor leads to negligible pressure drop along the reactor and improvement in CO2 conversion to methanol that has positive environmental effects. Also, water mole fraction decreases along the reactors of AW and ACW configurations to prevent the deactivation of catalyst active sites. Eventually, methanol production rates by AW and ACW configurations are improved around 25.5% and 43.1% in comparison with CR configuration. So, novel AW and ACW configurations provide many benefits including improvement in catalyst activity and durability, CO2 conversion, and the methanol production rate.

Mal-distribution of temperature in an industrial dual-bed reactor for conversion of CO2 to methanol

Design of dual type methanol reactor includes a gas cooled reactor for methanol synthesis. The gas cooled reactor faces with the problem of gas condensate formation and two phase flow in the practical operating conditions owing to a high temperature drop in the last 2 m of the reactor length. In this study, three strategies are proposed in order to prevent gas condensate formation in the gas cooled reactor which is designed based on dual type design. The first strategy is utilization of a partial condenser before the gas cooled reactor, the second strategy is injection of hot synthesis gas (HGS) to the last 2 m of the reactor and the third is warming the shell side of the reactor with steam in a jacket (JS) around the last 2 m of the reactor. Simulation results show that, the most effective strategy (ES) is application of a partial condenser to separate the methanol and water in the inlet of the gas cooled reactor by condensation. In ES, the dew point temperature in the porous media reduces via in-situ methanol and water removal at the inlet of the gas cooled reactor and gas temperature ascends along the length of the reactor. Moreover, methanol production enhances about 7.9% and CO2 decreases 2.6% in ES rather than in the conventional methanol synthesis reactor (CR). The elimination of the gas condensate formation on one hand and enhancing the methanol production and decreasing CO2 emission on the other hand can be considered as the superiority of the suggested ES to the CR and other strategies.

A novel cascade membrane reactor concept for methanol synthesis in the presence of long-term catalyst deactivation

In this study, a dynamic model for a novel cascade membrane methanol reactor (CMMR) in the presence of long term catalyst deactivation was developed. In the first catalyst bed the synthesis gas partially convert to methanol. In the second reactor the reaction heat is used to preheat the feed gas to the first bed. The wall of the tubes in the both of reactors is covered with a palladium–silver membrane. The simulation results represent 4.7% and 3.92% enhancement in the yield of methanol production during 1400 days of operation in the CMMR in comparison with conventional dual type methanol reactor (CDMR) and membrane dual type methanol reactor (MDMR), respectively and a favorable profile of temperature and activity along the CMMR relative to MDMR and CDMR. Copyright © 2010 John Wiley & Sons, Ltd.

Contribution to emission reduction of CO 2 by a fluidized-bed membrane dual-type reactor in methanol synthesis process

In this work, a fluidized-bed membrane dual-type reactor was evaluated for CO 2 removal in methanol synthesis process. The feed synthesis gas is preheated in the tubes of the gas-cooled reactor and flowing in a counter-current mode with reacting gas mixture in the shell side. Due to the hydrogen partial pressure driving force, hydrogen can penetrate from feed synthesis gas into the reaction side through the membrane. The outlet synthesis gas from this reactor is fed to tubes of the water-cooled packed-bed reactor and the chemical reaction is initiated by the catalyst. The methanol-containing gas leaving this reactor is directed into the shell of the gas-cooled reactor and the reactions are completed in this fluidized-bed side. A two-phase dynamic model in bubbling regime of fluidization was developed in the presence of long-term catalyst deactivation. This model is used to compare the removal of CO 2 in a FBMDMR with a conventional dual-type methanol synthesis reactor (CDMR) and a membrane dual-type methanol synthesis reactor (MDMR). The simulation results show a considerable enhancement in the CO 2 conversion due to have a favourable profile of temperature and activity along the fluidized-bed membrane dual-type reactor relative to membrane and conventional dual-type reactor systems.

Dynamic simulation of a cascade fluidized-bed membrane reactor in the presence of long-term catalyst deactivation for methanol synthesis

In this work, a dynamic model for a cascade fluidized-bed hydrogen permselective membrane methanol reactor (CFBMMR) has been developed in the presence of long-term catalyst deactivation. In the first catalyst bed, the synthesis gas is partly converted to methanol in a water-cooled reactor, which is a fluidized-bed. In the second bed, which is a membrane assisted fluidized-bed reactor, the reaction heat is used to preheat the feed gas to the first bed. This reactor configuration solves some observed drawbacks of new conventional dual type methanol reactor (CDMR) and even fluidized-bed membrane dual type methanol reactor (FBMDMR) such as pressure drop, internal mass transfer limitations, radial gradient of concentration and temperature in both reactors. A dynamic two-phase theory in bubbling regime of fluidization is used to model and simulate the proposed reactor. The proposed model has been used to compare the performance of a cascade fluidized-bed membrane methanol reactor with fluidized-bed membrane dual-type methanol reactor and conventional dual-type methanol reactor. The simulation results show a considerable enhancement in the methanol production due to the favorable profile of temperature and activity along the CFBMMR relative to FBMDMR and CDMR systems.

Enhancement of methanol production in a novel cascading fluidized-bed hydrogen permselective membrane methanol reactor

In this work, a novel cascading fluidized-bed hydrogen permselective membrane methanol reactor (CFBMMR) concept has been proposed. In the first catalyst bed, the synthesis gas is partly converted to methanol in water-cooled reactor which is a fluidized-bed. In the second bed which is a membrane assisted fluidized-bed reactor, the reaction heat is used to preheat the feed gas to the first bed. This reactor configuration solves some observed drawbacks of new conventional dual-type methanol reactor even better than fluidized-bed membrane dual-type methanol reactor (FBMDMR). The two-phase theory in bubbling regime of fluidization is used to model and simulate the proposed reactor. The proposed model has been used to compare the performance of a CFBMMR with industrial dual-type methanol reactor (IDMR) and FBMDMR. This comparison shows that fluidizing catalyst bed in the water-cooled reactor caused a favourable temperature profile along the CFBMMR. Additionally, the simulation results represent 3.94% and 9.53% enhancement in the yield of methanol production in comparison with FBMDMR and IDMR respectively.

Enhancement of methanol production in a novel fluidized-bed hydrogen-permselective membrane reactor in the presence of catalyst deactivation

In this study, a dynamic model for a novel bubbling fluidized-bed membrane dual-type methanol reactor has been developed in the presence of long-term catalyst deactivation. The proposed model has been used to compare the performance of a novel fluidized-bed membrane dual-type methanol reactor (FMDMR) with membrane dual-type methanol reactor (MDMR) and conventional dual-type methanol reactor (CDMR). In this new concept, the feed synthesis gas is preheated in the tubes of the gas-cooled reactor and flowing in a counter-current mode with reacting gas mixture in the shell side. Due to the hydrogen partial pressure driving force, hydrogen can penetrate from feed synthesis gas into the reaction side through the membrane. The outlet synthesis gas from this reactor is fed to tubes of the water-cooled packed-bed reactor and the chemical reaction is initiated by the catalyst. The methanol-containing gas leaving this reactor is directed into the shell of the gas-cooled reactor and the reactions are completed in this fluidized-bed side. This reactor configuration solves some observed drawbacks of new conventional dual-type methanol reactor such as pressure drop, internal mass transfer limitations, radial gradient of concentration and temperature in gas-cooled reactor. The proposed dynamic model has been validated against measured daily process data of a methanol plant recorded for a period of four years and a good agreement has been achieved. The simulation results show there is a favorable profile of temperature and activity along the fluidized-bed membrane dual-type reactor relative to membrane and conventional dual-type reactor systems. Therefore, the performance of methanol reactor system improves when membrane assisted fluidized-bed concept is used for conventional dual-type reactor system.

Enhancement of carbon dioxide removal in a hydrogen-permselective methanol synthesis reactor

One of the major problems facing mankind in 21st century is the global warming which is induced by the increasing concentration of carbon dioxide and other greenhouse gases in the atmosphere. One of the most promising processes for controlling the atmospheric CO 2 level is conversion of CO 2 to methanol by catalytic hydrogenation. In this paper, the conversion of CO 2 in a membrane dual-type methanol synthesis reactor is investigated. A dynamic model for this methanol synthesis reactor was developed in the presence of long-term catalyst deactivation. This model is used to compare the removal of CO 2 in a membrane dual-type methanol synthesis reactor with a conventional dual-type methanol synthesis reactor. A conventional dual-type methanol synthesis reactor is a vertical shell and tube heat exchanger in which the first reactor is cooled with cooling water and the second one is cooled with synthesis gas. In a membrane dual-type methanol synthesis reactor, the wall of the tubes in the conventional gas-cooled reactor is covered with a palladium–silver membrane, which is only permeable to hydrogen. Hydrogen can penetrate from the feed synthesis gas side into the reaction side due to the hydrogen partial pressure driving force. Hydrogen permeation through the membrane shifts the reaction towards the product side according to the thermodynamic equilibrium. The proposed dynamic model was validated against measured daily process data of a methanol plant recorded for a period of 4 years and a good agreement was achieved.

Dynamic optimization of membrane dual-type methanol reactor in the presence of catalyst deactivation using genetic algorithm

This paper presents a study on optimization of a membrane dual-type methanol reactor in the presence of catalyst deactivation. A theoretical investigation has been performed in order to evaluate the optimal operating conditions and enhancement of methanol production in a membrane dual-type methanol reactor. A mathematical heterogeneous model has been used to simulate and compare the membrane dual-type methanol reactor with conventional methanol reactor. An auto-thermal dual-type methanol reactor is a shell and tube heat exchanger reactor which the first reactor is cooled with cooling water and the second one is cooled with synthesis gas. In a membrane dual-type reactor the wall of the tubes in the gas-cooled reactor is covered with a pd–Ag membrane, which is only hydrogen-permselective. The simulation results have been shown that there are optimum values of reacting gas and coolants temperatures to maximize the overall methanol production. Here, genetic algorithms have been used as powerful methods for optimization of complex problems. In this study, the optimization of the reactor has been investigated in two approaches. In the first approach, the optimal temperature profile along the reactor has been studied and then a stepwise approach has been followed to determine the optimal profiles for saturated water and gas temperatures in three steps during the time of operations to maximize the methanol production rate. The optimization methods have enhanced 5.14% and 5.95% additional yield throughout 4 years of catalyst lifetime for first and second optimization approaches, respectively.

Co‐current and Countercurrent Configurations for a Membrane Dual Type Methanol Reactor

AbstractA dynamic model for a membrane dual‐type methanol reactor was developed in the presence of catalyst deactivation. This reactor is a shell and tube type where the first reactor is cooled with cooling water and the second one with feed synthesis gas. In this reactor system, the wall of the tubes in the gas‐cooled reactor is covered with a palladium‐silver membrane which is only permeable to hydrogen. Hydrogen can penetrate from the feed synthesis gas side into the reaction side due to the hydrogen partial pressure driving force. Hydrogen permeation through the membrane shifts the reaction towards the product side according to the thermodynamic equilibrium. Moreover, the performance of the reactor was investigated when the reaction gas side and feed gas side streams are continuously either co‐current or countercurrent. Comparison between co‐current and countercurrent mode in terms of temperature, activity, methanol production rate as well as permeation rate of hydrogen through the membrane shows that the reactor in co‐current configuration operates with lower conversion and also lower permeation rate of hydrogen but with longer catalyst life than does the reactor in countercurrent configuration.

A comparison of co-current and counter-current modes of operation for a dual-type industrial methanol reactor

In this paper, the dynamic behavior of a dual-type methanol reactor is investigated. For simulation purposed, a heterogeneous one-dimensional model has been developed. In the dual-type reactor system, a system with two-catalyst bed instead of one single catalyst bed is developed for methanol synthesis. In the first catalytic reactor, the synthesis gas is partly converted to methanol in a conventional water-cooled type reactor. In the second reactor, the reaction heat is used to preheat the feed gas to the first reactor. The continuously reduced temperature in this reactor provides increasing thermodynamic equilibrium potential. The proposed model was validated against measured daily process data of a methanol plant recorded for a period of 4 years and a good agreement was achieved. The validity of this model is also shown to be satisfactory for the investigation of the effect of co-current and counter-current flow pattern on performance of reactor. In the co-current mode, feed gas is entered into the tubes of the second reactor in the same direction with the reacting gas stream in shell side while in the counter-current mode the gas streams are in the opposite direction. Simulation results for both co-current mode and counter-current mode have been compared in terms of temperature, activity and methanol production rate. The results of this work show that the reactor in co-current mode operates with lower conversion but with longer catalyst lifetime in comparison with counter-current mode.