Structured Packaging and their Different Use in Chemical Engineering and Filtration

The term structured packing refers to a range of specifically designed materials that are used in the absorption and distillation columns and also In numerous chemical reactors. Structured packings are typically composed of thin layered corrugated metal plates or gauzes which are arranged in such a way that force fluids to take different paths through the column. This facilitates the proper segregation and contact of different phases. This also creates a large surface area for the proper contact between different phases.

Why structured packaging is used?

Structured packing is generally formed from the corrugated sheets of perforated embossed metal, plastic materials of different pore sizes or wire gauze. This results in the formation of a honeycomb like structure for the proper separation and movement of the fluids and also gives a relatively large surface area but with very low resistance to gas flow. This particular method of filtration or packaging is chosen for the better spreading of the liquid. These characteristics of the structured packaging shows significant results under low pressure and low irrigation rate application cases as well.

Different types of Structured packaging: -

Structured packing is manufactured in a huge range of sizes by creating variation in the crimp altitude. The Packaging surface ranges from 50 m²/m³ which has the lowest efficiency and highest capacity to 750 m²/m³ having the highest efficiency and the lowest capacity. There are numerous structured packaging manufacturers in India, manufacturing different variants and types of structured packaging for use in different purposes.

Advantages of structured packaging: -

There are certain advantages of using structured packaging, which has made this tool popular in the field on chemical engineering;

• Structured packaging offers lower drop in pressure.
• It provides high efficiency for fluidic mobility.
• It reduces the time of liquid hold-up.

Applications of structured packaging: -

Typical applications of structured packaging include vacuum and atmospheric crude oil fractionators, FCC main fractionators and TEG contactors. There are numerous TEG contractors in Pune who use different types of structured for assembling their setup. The separation of mono-, di- and triethanolamine, conducted under vacuum, also requires active use of structured packaging, due to its relatively low pressure drop. Tail oil fractionation is also another process in which structured packaging is used.

Structured packing also has numerous use in the fields and processes written below: -

• Air separation 
• Separation of Cyclohexanone/Cyclohexanol 
• Xylene splitters
• Absorption of CO2
• Absorption of H2S 
• Ethylene oxide absorbers
• Absorption of Acrylonitrile 

Types of Column Internals - Trays and Plates

Column internal refers to the separation and interaction devices used in the columns. For the structured packaging, this will consist of Liquid distributor VEP, Pipe type liquid distributor, Liquid distributor cum collector, Channel type distributor, and Trough type liquid distributor. For Random packaging, this consists of Pan Distributor, channel type, multibeam support, Antenna type, liquid distributor, and bed limiter.

Uses of the column internals

The application areas include Agrochemicals, Pharmaceuticals, Petrochemicals, Bulk drugs, Oil and gas industries, Pesticides and fertilizers, and Aromatic and essential oils. You can get the specifics for each from the Column Internals Manufacturers for each industry. Here we take a look at the column internals for the distillation columns.

In the trays and plates, the bubble cap tray has riser or chimney fitted over each hole in the tray. A cap covers the riser. You have a space between the cap and the riser. This allows the vapor passage. The rising vapor passes through the chimney but remains held down by the cap. The discharge finally occurs through the slots in the cap. They then bubble through the liquid on the tray.

Working of the sieve trays  

Sieve trays are much simpler. They are trays with holes in them. The size of the holes determines the rise of the vapor and the flow of the liquid. The arrangement and the size of the holes will determine the separation of the liquid and vapor. Valve trays have liftable caps. These react to the pressure of the rising vapor. When enough vapor has passed, the caps drop back into place.

The tower internals refers to the plates, trays, and devices used in the tower for getting the ideal efficiency and flow. You can find out the different options available from the Tower Internals Manufacturers in Pune. This will include the following:

1. Liquid distributor
2. Support plate
3. Feed device
4. Non-metallic internals
5. Bed limiter
6. Collector tray
7. Liquid extraction internals

There are many types of designs available in each. For example, you can have the Liquid Distributor With Flow Multiplier, Distributor V Weir Type, Distributor Trough Type With Parting Box, Or Distributor Pipe Arm Type.

Design of Tower Internals for Low and Medium Specific Liquid Load

The main component of the packed columns are the liquid distributors. These help ensure there is uniformity of the flow of the liquid. The distributor remains attached to the column shell. They remain close together at the top of the bed. The holes pattern and the liquid flow are the characteristics that influence the design criterion of the distributor.

Placement of holes  

To ensure the uniformity of distribution, they pay attention to both the holes pattern and the liquid flow. The distributor floor has holes or they are present in the sides of the trough. For different models, check the website of the Tower Internals Manufacturers in Pune. The size of the pitch gives the number of drip points. If the specific surface of the packaging increases, the number of points should be more. You should also ensure that the number of points in the periphery of the distributor is the same as everywhere else.

The second thing to watch for is that the liquid flow through each hole is the same. This will remain true if you ensure that the planarity of the distributor is true. You should make holes only by punching and avoid drilling. Look out for high velocities and turbulence. The liquid level must remain constant throughout the process.

Prevention of fouling

Presence of polymers and scales can result in fouling. Coking of the distributor may also result in blockages. If you use medium or low specific liquid load, then you can use a trough type distributor. You can use any fractionation bed and this will prevent the fouling. You can get the details for this from the Oil and Gas Internals Manufacturers in Pune. Here the holes remain punched in the sides of the trough and must remain bigger than 5mm. You must give at least 50 mm clearance from the bottom of the trough.