Reactors are used to carry out a chemical reaction in a vessel, often made of stainless steel or glass lined carbon steel. Aaron Equipment sells a large selection of reconditioned and unused industrial reactors.
When choosing the correct reactor for a reaction, a number of factors must be considered, including the reaction kinetics and process requirements. There are several common reactor types, such as Batch Reactors, Continuous Reactors, Packed Bed Reactors, and Fixed Bed Reactors.
Batch Reactors
Batch reactors are a type of chemical reaction equipment used to conduct reactions on an industrial scale. These chemical reactions are conducted in a closed system with the provision to apply utilities to heat or cool the reaction mass. These reactors are used in a variety of industries like Dyes and pigments, color and pharmaceutical industries.
In most cases, batch reactors use agitator systems with baffles to help achieve thorough mixing. However, the amount of energy required to power the agitator can be excessive, especially when handling large batches. This is due to the fact that some of the product can stick to the walls of the vessel and impede proper mixing.
In addition, the process of converting monomers to polymer in a batch reactor is exothermic. The polymer particles generate heat and the system needs to compensate for this energy with additional heater current or coolant flow rate. This can lead to hot or cold spots within the reactor, which may jeopardize quality and yield. These problems can be managed by using a multi stage continuous flow reactor (CSTR). This allows the residence time distribution to be controlled and minimizes variation from batch-to-batch.
Continuous Reactors
Continuous reactors feed in reactants at one point, allow the reaction to take place and withdraw the products from another point. The process is continuous and there must be an equal flow rate of reactants and products. A good example of a continuous chemical process is the water softener that takes hard water from a pipe, passes it through an ion-exchange resin, and then produces soft water at the other end.
Continuous processes require less process knowledge and customization of equipment but can be more costly in terms of utility costs per tonne produced. The residence time distribution can be controlled more precisely with continuous reactors allowing the process to operate more efficiently. buy reactors from best seller surplusrecord.
For continuous reactors, a well-engineered design is crucial to achieve the best results. Otherwise, the process may suffer from dead space or short-circuiting. These phenomena happen when the fluid spends less time in the reactor than what would theoretically be the case (tau ). In this instance, conditions within the reaction area can change causing a different reaction to occur. This can lead to undesirable side reactions.
Continuous Stirred Tank Reactors
Often called CSTRs, these agitated tanks are continuously fed and emptied with pipes for supplying reactants and draining products. They can handle solids, offer superior mixing, and can be scaled to a large size. They provide a wide range of operating conditions with demonstrated performance over decades and behave well at different scales.
Ideally, an ideal continuous stirred tank reactor has perfect mixing and the composition of the output stream holds the same as the inlet stream. However, chemistry is not always that simple.
Residence time distribution in a CSTR can be broad, with a long tail of time that is very dependent on the concentration of species inside the reactor. This makes achieving a desired reaction rate a challenge.
Unlike batch reactors, CSTRs allow for reactions to occur in real-time. This helps chemists achieve more accurate results and allows for faster reactions. In addition, CSTRs can be easily scaled up or down based on production needs and provide flexibility for industrial applications. They also allow for lower energy input and greater heat capacity than other reactor types.
Chemical Vapor Deposition Reactors
Chemical vapor deposition is a type of coating process where gaseous chemical precursors are deposited onto a substrate to form a thin film. This process allows for a wide variety of materials to be produced and characterized using varying environmental conditions including the temperature of the substrate and reaction chamber, the composition of the reactant gases and their total pressure gas flows.
The CVD process is very common in the manufacturing of thin-film photovoltaic solar cells, for example. It is also used to coat cutting tools, preventing corrosion and wear. This coating improves the lubricity of the tool and increases its thermal barrier.
APCVD reactors are often used in the microelectronics industry to deposit thin layers of semiconductor material such as silicon (dioxide, carbide and nitride) and gallium arsenide on semiconductor wafers. LPCVD reactors have similar designs to APCVD but operate at lower pressures, with the typical operating pressure between 0.1 and 2 torr. These reactors can be configured to load multiple wafers vertically or horizontally. They also feature a rotating fluidized bed that concentrates powdered reactants and maintains their fluidization independent of the powder's characteristics.
Fixed Film Reactors
A fixed film reactor is a process used for anaerobic treatment of organic waste. It consists of a membrane-attached biofilm with permeable tubular support material. It is capable of treating all industrial wastes containing organic compounds at reasonable concentrations. Currently, however, it is not able to treat municipal wastewater.
Reactions in a fixed film system are typically driven by diffusive mass transfer and first-order kinetics. Several factors affect the substrate conversion rates including inlet conditions, the reactor type (characterized hydraulically as plug-flow, plug-flow with dispersion and mixed-flow) and the biofilm kinetic constants.
Unlike other types of used reactors, fixed bed reactors require refuelling, which is done during shutdown by disconnecting the pressure tubes that surround the nuclear fuel assemblies. This is usually done every 12 to 24 months, during which a quarter to a third of the fuel assemblies are replaced with new ones. The fuel assemblies consist of pellets of uranium oxide and a matrix to hold them in place. The reactors are usually configured as a circle of pressure tubes, with the uranium dioxide rods in the centre of the ring, but there are also other designs that use a square configuration.
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