Gas-solid reactions in the mechanically generated fluidised bed
Customised reactor solutions for a wide variety of applications
Whether oxidations using oxygen gas or reactions with carbon dioxide or with ammonia: there is a wide range of possibilities for gas-solid reactions in reaction process technology. This is particularly so for heterogeneous syntheses, such as modern chemical and pharmaceutical production requires. For this reason, it is important that reactor solutions are customised and application-specific. Because even small procedural details determine the quality of the process and product.
The variety of chemical gas-solid reactions is as vast as the number of industrial gases. As a result, the controlled performance of chemical reactions is no longer limited to homogeneous, single-phase systems. Rather, heterogeneous syntheses, where applicable, using catalysts dominate today.
In every case, application possibilities for reactions with gaseous reactants in the chemical and pharmaceutical industry are highly diversified: for instance, many reaction processes use carbon dioxide gas or dry ice. Carboxylation for producing carbonic acid is roughly based upon the reaction of organometallic compounds with carbon dioxide, known as Grignard reactions. The reaction of carbon dioxide with phenolate, which produces salicylic acid derivatives (known as Kolbe-Schmitt reaction – a reaction stage in the synthesis of aspirin) are conducted in like manner. And also ammonia gas, a primary product of the chemical industry, forms the basis for many syntheses, for example in the fertiliser industry. Additional widespread examples for processes in reactors are oxidations with pure oxygen or an oxygen-ozone mixture, for instance for disinfection or bleaching. Also possible are processes with slightly boiling liquids such as ethylene oxide or propylene oxide and high vapour pressure (within the thredhold range of the gas phase). Methyl chloride is often used as a methylation reagent in organic chemistry. And dimethylamine is used in many areas of industry for the introduction of dimethyl amino groups.
All these chemical processes take place in reactors. Yet, which process can be optimally realised in which reactor? The answer to this question is, of course, critical for success. The details determine which procedural solution makes the most sense for the respective task. Thus, the answer is: customized reactor solutions.
(double click on picture to open in new window)
The reactor sizes vary from small laboratory devices with 5 litre drum capacity
to production machinery with volumes of more than 50,000 litres
Gas-solid reactions as process-related task
There are three types of systems from which to choose, especially for the reactions of gases with solids, and thus, for the above-mentioned processes. These are rotary kilns, solid bed reactors and fluidised bed reactors, such as the Druvatherm fluidised bed reactor from Loedige. The reactor types differ in their control of the respective thermodynamic und kinetic reaction processes. The difference between the three variants thus lies primarily in the nature of the flow control: rotary kilns make use of a solid material bed over which gas flows. Solid bed reactors, on the other hand, work with a solid material bed through which the gas flows. In fluidised bed reactors the solid material bed is moved intensively during the reaction process.
Such a fluidised bed reactor is a complex special form of a mixer. For the optimum design of a fluidised bed reactor, as it is used in the chemical and pharmaceutical industry, the respective requirements for the mixing process in the reactor necessary for that product must be precisely analysed. In the planning process this means specifically: the customer and the mechanical engineer develop the process together to ensure optimum results in terms of reaction- and machine technology.
Tailor-made reactor types
There are a multitude of technical possibilities for the application-specific requirements for gas-solid reactions. The diverse portfolio of Druvatherm fluidised bed reactors from Loedige offer the perfect solution for each type of application. These range from "simple" solid material mixers to drying systems and to the pressure vessel for reactions subject to overpressure. In practice, Loedige has already realised working overpressures of up to 40 bar in a reactor. The reactor sizes vary from small laboratory devices with 5 litre drum capacity to production machinery with volumes of more than 50,000 litres.
These devices can be used for batch operation as well as for continuous production lines. The solid particles move in these reactors in a circulating fluidised bed generated mechanically in the drum. This is generated by the input of energy via a horizontally arranged shaft equipped with mixing elements. Via a heat transfer medium – such as water, steam, thermal oil or molten salt – thermal energy is supplied or discharged. By means of electrical heating, temperature ranges of up to 700°C are achieved. High heat transfer coefficients are realised using a mixing drum equipped with a double jacket. The shaft can optionally be included in the heating or cooling circuit Additional rapidly rotating choppers in the reaction chamber bring shearing strain into the product and open up additional procedural possibilities. The creation of a vacuum or the use of carrier gas expands the performance range of the Loedige fluidised bed reactor with drying systems, what are known as shovel dryers. The selection of the respective material qualities as well as of the mixing elements and sealing technology is always individually adapted to the process.
(double click on picture to open in new window)
There are a multitude of technical possibilities for the application-specific requirements
for gas-solid reactions. The diverse portfolio of Druvatherm fluidised bed reactors from
Loedige offer the perfect solution for each type of application.
Chemical reactions in the fluidised bed reactor
With the described mixing technology in the fluidised bed reactor, reactions can be performed in multiphase systems (solid-liquid-gas) with outstanding results. In the mechanically generated fluidised bed there is homogeneous heat and concentration distribution. This is important insofar as temperature gradients, thus inhomogeneous temperature distribution, would have a limiting influence on the rate-determining sub-steps of the reactions (material transport, diffusion). For the gas-solid reactions there are two options: in the first, the reaction gas flows through the fluidised bed. In the second, the reactor is filled with the respective stoichiometric amount and the reaction is conducted in a closed system under pressure and with the addition of temperature. The latter procedural method, of course, has an accordingly positive effect on the reaction kinetics.
The fluidised bed reactors thus offer a wide range of possibilities in the variable liquid and gas dosage with respective reaction control. Parameters such as overpressure, temperature control via double jacket and cooler or final drying in a vacuum can be controlled very precisely. For this reason, certain reactors are particularly suited to conducting what is known as one-pot reactions. Likewise, a continuous gas flow through the solid fluidised bed of a continually operated reactor is conceivable.
Conclusion
Gas-solid reactions, which are a daily occurrence in the chemical industry, pose complex procedural challenges. There is a broad range of suitable reactors available to ensure optimum application-specific implementation. The decisive factor here is that the best, tailor-made solution is chosen from this portfolio. In the end, procedural details determine which machine type is best suited to each case.
Loedige at Powtech 2014 – 30 September to 2 October 2014 –
Loedige: Customised Reactor Solutions
Gas-solid reactions in the mechanically generated fluidised bed
Customised reactor solutions for a wide variety of applications
Whether oxidations using oxygen gas or reactions with carbon dioxide or with ammonia: there is a wide range of possibilities for gas-solid reactions in reaction process technology. This is particularly so for heterogeneous syntheses, such as modern chemical and pharmaceutical production requires. For this reason, it is important that reactor solutions are customised and application-specific. Because even small procedural details determine the quality of the process and product.
The variety of chemical gas-solid reactions is as vast as the number of industrial gases. As a result, the controlled performance of chemical reactions is no longer limited to homogeneous, single-phase systems. Rather, heterogeneous syntheses, where applicable, using catalysts dominate today.
In every case, application possibilities for reactions with gaseous reactants in the chemical and pharmaceutical industry are highly diversified: for instance, many reaction processes use carbon dioxide gas or dry ice. Carboxylation for producing carbonic acid is roughly based upon the reaction of organometallic compounds with carbon dioxide, known as Grignard reactions. The reaction of carbon dioxide with phenolate, which produces salicylic acid derivatives (known as Kolbe-Schmitt reaction – a reaction stage in the synthesis of aspirin) are conducted in like manner. And also ammonia gas, a primary product of the chemical industry, forms the basis for many syntheses, for example in the fertiliser industry. Additional widespread examples for processes in reactors are oxidations with pure oxygen or an oxygen-ozone mixture, for instance for disinfection or bleaching. Also possible are processes with slightly boiling liquids such as ethylene oxide or propylene oxide and high vapour pressure (within the thredhold range of the gas phase). Methyl chloride is often used as a methylation reagent in organic chemistry. And dimethylamine is used in many areas of industry for the introduction of dimethyl amino groups.
All these chemical processes take place in reactors. Yet, which process can be optimally realised in which reactor? The answer to this question is, of course, critical for success. The details determine which procedural solution makes the most sense for the respective task. Thus, the answer is: customized reactor solutions.
(double click on picture to open in new window)
The reactor sizes vary from small laboratory devices with 5 litre drum capacity
to production machinery with volumes of more than 50,000 litres
Gas-solid reactions as process-related task
There are three types of systems from which to choose, especially for the reactions of gases with solids, and thus, for the above-mentioned processes. These are rotary kilns, solid bed reactors and fluidised bed reactors, such as the Druvatherm fluidised bed reactor from Loedige. The reactor types differ in their control of the respective thermodynamic und kinetic reaction processes. The difference between the three variants thus lies primarily in the nature of the flow control: rotary kilns make use of a solid material bed over which gas flows. Solid bed reactors, on the other hand, work with a solid material bed through which the gas flows. In fluidised bed reactors the solid material bed is moved intensively during the reaction process.
Such a fluidised bed reactor is a complex special form of a mixer. For the optimum design of a fluidised bed reactor, as it is used in the chemical and pharmaceutical industry, the respective requirements for the mixing process in the reactor necessary for that product must be precisely analysed. In the planning process this means specifically: the customer and the mechanical engineer develop the process together to ensure optimum results in terms of reaction- and machine technology.
Tailor-made reactor types
There are a multitude of technical possibilities for the application-specific requirements for gas-solid reactions. The diverse portfolio of Druvatherm fluidised bed reactors from Loedige offer the perfect solution for each type of application. These range from "simple" solid material mixers to drying systems and to the pressure vessel for reactions subject to overpressure. In practice, Loedige has already realised working overpressures of up to 40 bar in a reactor. The reactor sizes vary from small laboratory devices with 5 litre drum capacity to production machinery with volumes of more than 50,000 litres.
These devices can be used for batch operation as well as for continuous production lines. The solid particles move in these reactors in a circulating fluidised bed generated mechanically in the drum. This is generated by the input of energy via a horizontally arranged shaft equipped with mixing elements. Via a heat transfer medium – such as water, steam, thermal oil or molten salt – thermal energy is supplied or discharged. By means of electrical heating, temperature ranges of up to 700°C are achieved. High heat transfer coefficients are realised using a mixing drum equipped with a double jacket. The shaft can optionally be included in the heating or cooling circuit Additional rapidly rotating choppers in the reaction chamber bring shearing strain into the product and open up additional procedural possibilities. The creation of a vacuum or the use of carrier gas expands the performance range of the Loedige fluidised bed reactor with drying systems, what are known as shovel dryers. The selection of the respective material qualities as well as of the mixing elements and sealing technology is always individually adapted to the process.
(double click on picture to open in new window)
There are a multitude of technical possibilities for the application-specific requirements
for gas-solid reactions. The diverse portfolio of Druvatherm fluidised bed reactors from
Loedige offer the perfect solution for each type of application.
Chemical reactions in the fluidised bed reactor
With the described mixing technology in the fluidised bed reactor, reactions can be performed in multiphase systems (solid-liquid-gas) with outstanding results. In the mechanically generated fluidised bed there is homogeneous heat and concentration distribution. This is important insofar as temperature gradients, thus inhomogeneous temperature distribution, would have a limiting influence on the rate-determining sub-steps of the reactions (material transport, diffusion). For the gas-solid reactions there are two options: in the first, the reaction gas flows through the fluidised bed. In the second, the reactor is filled with the respective stoichiometric amount and the reaction is conducted in a closed system under pressure and with the addition of temperature. The latter procedural method, of course, has an accordingly positive effect on the reaction kinetics.
The fluidised bed reactors thus offer a wide range of possibilities in the variable liquid and gas dosage with respective reaction control. Parameters such as overpressure, temperature control via double jacket and cooler or final drying in a vacuum can be controlled very precisely. For this reason, certain reactors are particularly suited to conducting what is known as one-pot reactions. Likewise, a continuous gas flow through the solid fluidised bed of a continually operated reactor is conceivable.
Conclusion
Gas-solid reactions, which are a daily occurrence in the chemical industry, pose complex procedural challenges. There is a broad range of suitable reactors available to ensure optimum application-specific implementation. The decisive factor here is that the best, tailor-made solution is chosen from this portfolio. In the end, procedural details determine which machine type is best suited to each case.
Loedige at Powtech 2014 – 30 September to 2 October 2014 –
Nuremberg Exhibition Centre: Hall 5/Stand 5-222
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