Peeling is a physical separation process in which one or more components are removed from the liquid stream by the steam stream. In industrial applications the flow of liquids and vapors may have an inverted current or current. Peeling is usually done either in packed or plotted columns.
Video Stripping (chemistry)
Theory
Peeling works based on mass transfer. The idea is to create favorable conditions for the component, A, in the liquid phase to transfer to the vapor phase. It involves a gas-liquid interface that A must cross. The total number of A moving across this boundary can be defined as the flux A, N A .
Maps Stripping (chemistry)
Tools
Peeling is mainly done in the cast tower (plate columns) and packed columns, and less frequently in spray towers, bubble columns, and centrifugal contactors.
The tray tower is made up of vertical columns with fluid flowing up and down the bottom. The vapor phase enters at the bottom of the column and exits from above. Inside the column there is a tray or plate. These trays force the fluid to flow back and forth horizontally while the steam bubbles upward through the hole in the tray. The purpose of this tray is to increase the number of contact areas between the liquid and steam phases.
The packed columns are similar to the placed columns in which the liquid and the vapor flow in and out in the same way. The difference is that in the packed tower there is no tray. Instead, packing is used to increase the contact area between the liquid and vapor phase. There are many types of packaging used and each has its own advantages and disadvantages.
Variables
Variables and design considerations for many strippers. Among them are incoming conditions, required solubility recovery rate, choice of stripping agent and flow, operating conditions, number of stages, heat effects, and type and size of equipment.
Recovery rates are often determined by environmental regulations, such as for volatile organic compounds such as chloroform.
Often, steam, air, inert gas, and hydrocarbon gas are used as stripping agents. It is based on solubility, stability, corrosion rate, and availability. As the stripping agent is a gas, operating at the highest temperature and the lowest pressure which will retain the component and not evaporate the desired liquid feed stream. This makes it possible to minimize flow. As with all other variables, minimizing the cost of achieving efficient separation is the ultimate goal.
The size of the equipment, and especially the height and diameter, is important in determining the possibility of flow distribution which will reduce the contact area between the liquid and steam streams. If flow channeling is suspected, a redistribution plate is often required to, as the name suggests, redistribute the flow of fluids evenly to rebuild the higher contact area.
As mentioned earlier, strippers can be cast or packed. Packed columns, and especially when random packing is used, are usually preferred for smaller columns with a diameter of less than 2 feet and a packed height of no more than 20 feet. Packed columns can also be useful for corrosive liquids, high foaming liquids, when high fluid velocity, and when very low pressure is desired. Striped stripper is advantageous because of its ease of design and scale. Structured packaging can be used similar to a tray even though it may be the same material as a random (discarded) packaging. Using structured packaging is a common method of increasing the separation capacity or replacing the damaged tray.
Striped stripper can have a sieve, valve, or bubble cap tray while the packed peeler can have structured packing or random packing. Trays and packers are used to increase the area of ​​contact where mass transfer can take place as a mass transfer theory dictates. Packaging can have a wide range of materials, surface area, flow area, and associated pressure drops. Older generations of packs include Raschig ceramic rings and pelapel Berl. The more common packaging materials are metal and plastic Pall ring, metal and plastic Zbigniew Bia? Ecki rings, and Intalox ceramic saddles. Each new generation material packaging increases the surface area, flow area, and/or associated pressure drop across the packaging. What is also important, is the packing material's ability not to accumulate above itself. If such buildup occurs, it drastically reduces the material surface area. Lattice design work has improved lately which will further enhance these characteristics.
During operation, monitoring the pressure drop in the columns can help determine the performance of strippers. A drop in pressure that changes over a significant span of time can be an indication that the packaging may need to be replaced or cleaned.
General app
Peeling is commonly used in industrial applications to remove harmful contaminants from waste streams. One example is the removal of TBT and PAH contaminants from port soils. The soil is dredged from below the contaminated port, mixed with water to make the slurry and then released with steam. The soil is clean and the vapor mixture is rich in contaminants then separated. This process is able to decontaminate the soil almost completely.
Steam is also often used as a stripping agent for water treatment. Vaporous organic compounds partially soluble in water and due to environmental and regulatory considerations, must be removed from groundwater, surface water and wastewater. These compounds may be present due to industrial, agricultural, and commercial activities.
See also
- Steam distillate
- Distillation
- Theoretical plates
- Continuous distillation
- Fractionation column
- Distillation Design
- Beds packed
References
Source of the article : Wikipedia
0 Comments