Why use a Rotating Bed Reactor?
When it comes to Industrial processing, the Rotating Bed Reactor (RBR) is an innovative technology for industrial applications with important benefits. This is due to its high scalability, lesser reaction time, and better product yields. In heterogeneous reactions, two types of reactors are commonly used: stirred tank reactors (STR) and packed bed reactors (PBR). Some problems are observed when using these reactors. It is important to eliminate these problems to increase efficiency and productivity. In this blog, problems, solutions and an alternative to these reactors is discussed.
These heterogeneous reactions involve reactants in different phases; usually a substrate dissolved in a liquid, and a solid catalyst or adsorbent. As diffusion is a slow process, different techniques are applied to achieve contact between the reactants in the two different phases. One approach is to pack the solid phase into a column through which the liquid phase is pumped, a set-up known as a packed bed reactor. When the flow rate in a PBR is high, it decreases the yield as the reaction doesn't have enough time to finish. Also, generates high back pressures at high flow rates, which might damage the solid phase particles, or require high-pressure equipment, thus restricting the viable flow rate. Alternatively, the flow takes the path of least resistance, known as channeling.
Another traditional approach is to use a STR. This comes with a large risk of damaging the solid phase (e.g. catalyst or adsorbent) by the mechanical forces imparted by the stirrer blades. The solid phase is broken down into fines, which have to be removed by filtration downstream of the reactor, potentially causing a process bottleneck.
A solution to the above problems is given by SpinChem's Rotating bed reactor (RBR) which is an alternative to these traditional reactors like the STR and PBR. The SpinChem RBR combines the working principles of both these reactor giving a better performance.
When using a SpinChem RBR, the solid phase is kept inside a rotating cylinder. As the cylinder spins, solution is repeatedly flushed through the packed bed within by centrifugal forces. This allows every liquid parcel to do multiple passages through the bed at high flow rates, without exposing the solid particles to pressure or stress. Also, this clever mechanism eliminates the risk of damaging the solid phase.
The use of a SpinChem RBR can streamline purification of large liquid volumes by decreasing the time and amount of solid phase material required to process a given liquid volume. The SpinChem RBR treats heterogeneous reactions and numerous types of solid phases, including immobilized enzymes, encapsulated cells, and ion exchangers. The RBR eliminates slow reactions kinetics caused by poor mass transfer between the solution and solid phase. SpinChem produces RBRs in different sizes for processing on any scale.
Technology and Mechanism
SpinChem's RBR consists of a rotating cylinder coupled to drive shaft. The cylinder contains the solid phase as a packed bed and rapidly aspirates the reaction solution from the bottom of the vessel, percolates it through the solid phase, and quickly returns it to the vessel. The rotating stirring element holds the solids inside, as a packed bed, while forcing a liquid to flow through the solids. The flow rate increases with higher rotation speed. For instance, beads with a diameter larger than 0.105 mm (140 US mesh) can be used.
As the RBR is submerged and rotated in the liquid reaction medium, the liquid can percolate through the packed bed for inducing a reaction. Because of the centrifugal force, the liquid between the beads will be pushed to the outer perimeter of the RBR as it rotates. The liquid is allowed to escape through holes in the perimeter that are fitted with a mesh so that the beads remain secured.
Through holes at the top and bottom side of the RBR, liquid from outside is drawn in to fill the void. This mechanism improves the solid-liquid external mass transfer, compared to a STR, in which solids and liquids are mixed with classical impellers. Using the SpinChem RBR and vessel, axial mixing and convective transport are maximized. The resulting efficient mass transfer minimizes reaction time and increases product yields. This applies even to liquids that are immiscible or of different viscosity, as well as for reactions demanding distribution of dissolved gases.
Advantages of the RBR
The RBR is fully scalable and provides more efficient reaction development and improved production economy. It can also be used for purification using metal scavengers, active carbons, and water adsorbents. Additionally, the SpinChem RBR extends the lifetime of solid phase particles by minimizing grinding and fines, while simplified solid phase collection and recycling. Listed are few more advantages of RBR.
- Short reaction time
- Simple to scale
- Long catalyst lifetime
- Easy to automate
- No filtration required
- Perfect for screening
- Improved production economy
Applications of the RBR
A rotating bed reactor can be used in various industries. Some of them are listed below:
Pharmaceuticals and Cosmetic Industry for synthesis, transition metal catalysis, hydrogeneration and metal scavenging.
Food and Beverages for processing and synthesis of ingredients and finished products including clarifying, contaminant removal, molecular modifications etc.
Environmental applications like Industrial wastewater treatment, contaminant removal, deionization, and nuclear liquid wastewater clean-up.
Thus, to avoid problems of high pressure and damage to the solid phase particles, and to achieve lesser reaction time, high scalability, better product yields, and to make the most of the alternative best technology, contact SpinChem today.
2022-01- 26 04:34