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difference between packed column and tray column:- In this article I would like to discuss the packed bed column and tray column . what is the application of the packed bed and tray column in fractional distillation? What role in the chemical industries would we like to focus in this article? Why it is important so we can understand easily by this article. Many of us confused the application of the packed bed and tray bed column. I am assuming that you can easily visualized clear difference by this article.
Fractional distillation is very common is chemical and pharmaceutical industries. There are simple distillation , fractional distillation and azeotropic distillation are the main types of distillation.
packed bed column
What is the packed bed column and important ?
The chemical and food industries, environmental protection, as well as processes in thermal power plants including water purification, flue gas heat utilization, and SO2 removal, all use packed bed columns extensively for absorption, desorption, rectification, and direct heat transfer.
The chemical and food industries, environmental protection, as well as processes in thermal power plants including water purification, flue gas heat utilization, and SO2 removal, all use packed bed distillation columns extensively for absorption, desorption, rectification, and direct heat transfer. According to estimates, these separation procedures account for 40% to 70% of the capital and operating expenditures in the process sector. In this region, packed bed columns are frequently used. Their use in direct heat transfer between gas and liquid expands the scope of their significance. They are the most effective tools for mass and heat transfer operations between the gas and liquid phases from a thermodynamic perspective. Their extensive distribution is a result of their low operating and capital expenses.
A packed bed is a hollow tube, pipe, or tank used in chemical processing that is filled with packing material. The packing may be haphazardly filled or it may be carefully planned and structured. Improved contact between two phases in a chemical or equivalent process is the main goal of a packed bed. Packed beds have also been used to store heat in chemical plants. Packed beds can be employed in a chemical reactor, a distillation process, or a scrubber. In this instance, hot gases are allowed to escape through a refractory material-packed vessel until the packing becomes hot. Then, air or another cool gas is delivered back through the hotbed to the plant, preheating the
Type of packed bed column
Structure packing
First , structured packing towers feature a lower pressure drop and larger surface area than packed towers. Corrugated sheets of perforated embossed metal, plastic, or wire gauze can be used to make structured packaging. The end product is a very open honeycomb structure with vertical flow channels that has very little flow resistance and a relatively high surface area to volume.
haphazard packing
Random packing
A range of metal or nonmetal materials, such as ceramic or plastic, are used to build packed towers. These substances provide the distillation process its surface area. The earliest packing material was the Raschig ring, although more recent designs offer minimal pressure drop and great surface area per unit volume.
What is the tray column ?
Bubble cap tray
The best solution for the low liquid and vapour pressure in the column is bubble cap trays. Vapor and liquid are trapped on the trays with the aid of the weir height. In the case of a high turndown ratio, bubble cap trays may be the best option.
Only the larger pressure drop on the vapour side is a drawback of the bubble cap trays. Where these trays are also more expensive.
Sieve tray
At the same fluid velocity, sieve trays have more entrainment than valve trays. Due to their simplicity and ease of fabrication, sieve trays are affordable.
The sieve trays’ lone drawback is their slowest hole velocity. To control the liquid head over the plates, it should be kept in good condition. In general, it gives a lower turndown ratio.
Valve tray
To increase efficiency, valve trays include movable discs in the shape of valves that move up and down. The valve moves and mass transfer takes place as the fluid flow rate changes. The valve is unable to move up in direction at the lowest vapour flow, holding both fluids above and below the plate.
Difference between packed column and tray column
This are the main two types of column used i chemical industries as well as oil ad gas industries. packed bed column use when there is no bigger diameter required as per process and tray column use if the required diameter is very high.
Read our some article for column internals.
Conclusion
Plate columns perform worse when there is a foaming system in place. Anti-foaming substances can be used to reduce foam.
High liquid hold up is present. The pressure drop as a result is very high. Due to the use of corrosion-resistant materials, plate columns for corrosive liquids are too expensive.
Cost-related supporting framework is necessary.
The prediction of HETP and HTU could not be very precise.
For very low liquid flows, packed columns are not appropriate.
In tightly packed columns, it is difficult to provide cooling arrangements.
In a filled column, side stream removal is not possible.
Read Also,
advantages and disadvantages of packed column
types of trays in distillation column
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