Evaluation of plate & shell type heat exchanger as millichannel reactor in methanol synthesis
Nuzair Ahamed, Mohamed (2022)
Diplomityö
2022
School of Engineering Science, Kemiantekniikka
Kaikki oikeudet pidätetään.
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi-fe2022111866197
https://urn.fi/URN:NBN:fi-fe2022111866197
Tiivistelmä
Methanol synthesis process is an alternative method to store renewable energy (power to X). There is a large demand for methanol as an energy source because of the fluctuation of renewable energy sources such as wind and solar. Excess electricity can be stored and utilized in the form of chemical energy.
The methanol synthesis reaction is highly exothermic. The size of conventional methanol reactors is very large, and they are expensive. In addition to that, catalyst degradation is a potential risk at high-temperature levels. Removing methanol reaction heat at optimal range is important to improve methanol yield and prevent catalyst degradation. Removing heat from the system to keep the production at a feasible temperature. A typical conventional methanol synthesis reactor is a multitubular tube and shell-type equipment. These types of reactors have a heat transfer area and heat removal capacity limitation.
Micro or millichannel reactors provide a much more compact size, lower capital and operational cost, and efficiently allow heat transfer millichannel reactors developed from plate and shell-type heat transfer equipment also tolerate high temperature and pressure. Catalyst in the form of washcoat layer or foam can be used to provide a high surface area to disperse catalyst metal and prevent undesired reactions. Washcoat materials, including metal oxides and metals, can be added as catalyst carriers and other metal oxides can also be added to enhance catalyst performance. Metal oxide foams are useful to reduce the size of the reactor and provide high conversions when dealing with highly exothermic.
This thesis work includes an evaluation of plate and shell-type heat exchangers that could be applied as a reactor in the methanol synthesis process. The experimental part of this thesis includes mockup experiments with heat transfer between hot water as a hot fluid and, air as the cooling medium. Mathematical modelling and simulations are carried out for foam catalyst at steady-state operation with COMSOL Multiphysics to study the feasibility of adopting a millichannel reactor in methanol synthesis at an industrial scale.
Plate and shell heat exchangers have been studied for several other applications such as HVAC applications regarding their efficiency, advantages, and limitations. However, so far, they have not been studied for methanol synthesis in the literature. Plate exchangers are used to remove heat generated by chemical reactions. Therefore, the key idea of this thesis work is the plate and shell heat exchanger can remove the heat of reaction which is generated inside the heat exchanger channel. This was studied from various perspectives such as heat transfer laboratory experiments, heat and mass balance and mathematical modelling. The aim of this work is to evaluate how well the plate & shell exchangers could operate as reactors in methanol synthesis compared to conventional reactors. The results that were obtained clarify that the heat exchanger is able to remove all the generated heat from the reaction.
The methanol synthesis reaction is highly exothermic. The size of conventional methanol reactors is very large, and they are expensive. In addition to that, catalyst degradation is a potential risk at high-temperature levels. Removing methanol reaction heat at optimal range is important to improve methanol yield and prevent catalyst degradation. Removing heat from the system to keep the production at a feasible temperature. A typical conventional methanol synthesis reactor is a multitubular tube and shell-type equipment. These types of reactors have a heat transfer area and heat removal capacity limitation.
Micro or millichannel reactors provide a much more compact size, lower capital and operational cost, and efficiently allow heat transfer millichannel reactors developed from plate and shell-type heat transfer equipment also tolerate high temperature and pressure. Catalyst in the form of washcoat layer or foam can be used to provide a high surface area to disperse catalyst metal and prevent undesired reactions. Washcoat materials, including metal oxides and metals, can be added as catalyst carriers and other metal oxides can also be added to enhance catalyst performance. Metal oxide foams are useful to reduce the size of the reactor and provide high conversions when dealing with highly exothermic.
This thesis work includes an evaluation of plate and shell-type heat exchangers that could be applied as a reactor in the methanol synthesis process. The experimental part of this thesis includes mockup experiments with heat transfer between hot water as a hot fluid and, air as the cooling medium. Mathematical modelling and simulations are carried out for foam catalyst at steady-state operation with COMSOL Multiphysics to study the feasibility of adopting a millichannel reactor in methanol synthesis at an industrial scale.
Plate and shell heat exchangers have been studied for several other applications such as HVAC applications regarding their efficiency, advantages, and limitations. However, so far, they have not been studied for methanol synthesis in the literature. Plate exchangers are used to remove heat generated by chemical reactions. Therefore, the key idea of this thesis work is the plate and shell heat exchanger can remove the heat of reaction which is generated inside the heat exchanger channel. This was studied from various perspectives such as heat transfer laboratory experiments, heat and mass balance and mathematical modelling. The aim of this work is to evaluate how well the plate & shell exchangers could operate as reactors in methanol synthesis compared to conventional reactors. The results that were obtained clarify that the heat exchanger is able to remove all the generated heat from the reaction.