Intermediate filtration issue
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We have an intermediate here; the solvent is n-hexane in a volume of 4000 L, and the weight of the filter cake is 400 kg. This intermediate has a certain degree of viscosity, and using a filtration tank does not yield satisfactory results. A two-in-one vibration dryer with filtering and drying functions also didn’t work well. Currently, centrifugation is used for drying, but since the boiling point of n-hexane is around -20 degrees Celsius, this poses a significant risk. Last Sunday, due to poor sealing of the centrifuge cover, n-hexane leaked into the motor belt, causing overheating and smoking. I hope everyone can suggest ways in which other equipment could be used without changing the manufacturing process.
Use an external bag filter, so that a filter cake is formed on the outer surface of the filter bag and then blown off in the reverse direction.
RVF can be considered, that is, a rotary vacuum filter
Could you provide information on the advantages and disadvantages, as well as the areas of application, of the RVF rotary drum vacuum filter?
For plate and frame filters, it was also considered, but I’m concerned that the filtration process won’t achieve sufficient dryness, there will be high solvent loss, and it’s difficult to clean the equipment on site, which could lead to contamination. What I have here are intermediates for active pharmaceutical ingredients.
Structure and working principle of RVF: It has a horizontal drum with openings in its walls; a support plate and filter cloth are laid on the drum surface to form the filtering surface. The space beneath the filter surface is divided into several separate sector-shaped filter chambers. Each filter chamber is connected to a distribution valve via a conduit. With each rotation of the drum, the various filter chambers take turns being connected to either the vacuum system or the compressed air system via distribution valves, thereby sequentially carrying out operations such as filtering, slag washing, drying, slag removal, and regeneration of the filtering medium (filter cloth). Across the entire filtering surface of the drum, the filtering zone accounts for about 1/3 of the circumference, the slag washing and drying zone accounts for 1/2, and the slag discharge zone accounts for 1/6; there are transition zones between these different zones. During filtration, the lower part of the drum is immersed in the suspension and rotates slowly. The filter chamber submerged in the suspension is connected to a vacuum system; the filtrate is drawn out of the filter, while the solid particles get adsorbed on the filter surface to form filter residue. After the filter chamber rotates away from the suspension along with the drum, it continues to draw out the liquid contained in the filter residue. When it is necessary to remove the residual filtrate from the filter residue, washing water can be sprayed when the filter chamber rotates to the upper part of the drum. At this point, the filter chamber is connected to another vacuum system, and the washing water passes through the filter residue layer to displace the remaining filtrate between the particles. The filtrate is drawn into the filter chamber and discharged separately, after which the dried filter residue is removed. At this point, the filter chamber is connected to the compressed air system, which loosens the filter residue; the residue is then removed by a scraper. Compressed air (or steam) continues to blow back against the filter cloth, clearing the pores and allowing it to be regenerated. This type of filter has a high processing capacity, is easy to operate, and allows the filter residue to be washed; it is typically used to filter suspensions with a high concentration of solid particles. Drum vacuum filters equipped with a pre-installed auxiliary filter layer can also be used for the clarifying filtration of thin suspensions
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