Random column packing

Random column packing refers to the practice of packing a distillation column with randomly fitting filtration material in order to optimize surface area over which reactants can interact while minimizing the complexity of construction of such columns. Random column packing is an alternative to structured column packing.

Packed columns

Packed columns utilizing filter media for chemical exchange are the most common devices used in the chemical industry for reactant contact optimization.[1] Packed columns are used in a range of industries to allow intimate contact between two immiscible/partly immiscible fluids, which can be liquid/gas or liquid/liquid. The fluids are passed through a column in a counter current flow. In the column it is important to maintain an effective mass transfer, so its essential that a packing is selected which will support a large surface area for mass transfer.[2][3]

History

Random packing was used as early as 1820. Originally the packing material consisted of glass spheres, however in 1850 they were replaced by a more porous pumice stone and pieces of coke.[4]

Applications

This shows a photo of Raschig rings

Random packed columns are used in a variety of applications, including:

Types

Raschig ring

Dixon rings

The Raschig ring is a piece of tube that is used in large numbers in a packing column. Raschig rings are usually made out of ceramic or metals, and they provide a large surface area within the column, allowing for interaction between liquid and gas vapors.[7][8]

Lessing ring

Lessing rings are made out of ceramic and are another type of random packing which was designed from the Raschig ring. Lessing rings have partitions insides which increase the surface area and enhance mass transfer efficiency. Lessing rings have a high density and an excellent heat and acid resistance. Lessing rings withstand corrosion and are used in regenerative oxide systems and transfer systems.[9][10]

Pall rings

Pall rings are the most common form of random packing. They are similar to Lessing rings and were developed from the Raschig ring. Pall rings have similar cylindrical dimensions but has rows of windows which increase performance by increasing the surface area. They are suited for low pressure drop and high capacity applications. They have a degree of randomness and a relatively high liquid hold up, promoting a high absorption, especially when the rate of reaction is slow. The cross structure of the Pall ring makes it mechanically robust and suitable for use in deep packed beds.[11][12]

Dixon rings

Dixon rings have a similar design to Lessing rings, however they are made out of stainless steel mesh, giving Dixon rings a low pressure drop and after pre-wetting. Dixon rings have a very large surface area, which increases the rate of mass transfer. Dixon rings have a large liquid hold up, a low pressure drop and a large surface area, all while still retaining a high mass transfer rate.[13] Dixon rings are used for distillation and CO2 scrubbing applications.[5][6]

References

  1. ↑ "Design of packed columns". www.slideshare.net. Retrieved 2018-07-24.
  2. ↑ Mohammad, Ghomi Avili; Javad, Karimi Sabet; Mohammad, Ghoreishi Seyyed (2018). "Pressure drop behavior and mass transfer properties of a high specific area random type packing in a narrow packed column". Journal of the Serbian Chemical Society (00): 37–37. doi:10.2298/JSC171204037G. ISSN 0352-5139.
  3. ↑ Carl,, Schaschke,. A dictionary of chemical engineering (First ed.). Oxford. ISBN 0191002690. OCLC 870517909.
  4. ↑ Xu, Bin; Gao, Hongxia; Chen, Menglin; Liang, Zhiwu; Idem, Raphael (2016-07-29). "Experimental Study of Regeneration Performance of Aqueous N,N-Diethylethanolamine Solution in a Column Packed with Dixon Ring Random Packing". Industrial & Engineering Chemistry Research. 55 (31): 8519–8526. doi:10.1021/acs.iecr.6b00936. ISSN 0888-5885.
  5. 1 2 Kolaczkowski, S.T.; Awdry, S.; Le, C.D.; Nuckols, M.L.; Smith, T.; Thomas, D. (August 2015). "Removal of CO2 from a submersible atmosphere by scrubbing with water—Experiments in a single column". Chemical Engineering Research and Design. 100: 157–169. doi:10.1016/j.cherd.2015.04.035. ISSN 0263-8762.
  6. 1 2 Kaba, Akira; Akai, Reijiro; Yamamoto, Ichiro; Kanagawa, Akira (October 1988). "Measurement of HETP of SUS Dixon Ring and Porcelain Packing in Small-Scale Water Distillation Column for H20-HTO Isotope Separation". Nuclear Science and Technology. 25 (10): 69–74.
  7. ↑ "Ceramic Raschig Rings | Equipment for Distillation". moonshinedistiller.com. Retrieved 2018-07-20.
  8. ↑ "Distillation Column Packing | OKUTANI Co., Ltd". 奥谷金網製作所 (in Japanese). 2012-09-15. Retrieved 2018-07-23.
  9. ↑ S. Fathalla, A (June 2016). "Rates of Mass Transfer Controlled Electrochemical and Catalytic Reactions Conducted in a Fixed Bed Reactor Built of Lessing Rings". International Journal of Electrochemical Science: 5207–5216. doi:10.20964/2016.06.34. ISSN 1452-3981.
  10. ↑ Hassan, I.; Zahran, R. R.; Mansour, I. S.; Sedahmed, G. H. (July 2005). "Liquid−Solid Mass Transfer at a Fixed Bed of Lessing Rings, in Relation to Electrochemical Reactor Design". Industrial & Engineering Chemistry Research. 44 (15): 5761–5767. doi:10.1021/ie040053f. ISSN 0888-5885.
  11. ↑ "Random Packing Manufacturers & Suppliers | Vadodara, Gujarat, India". www.ablazeglassworks.com. Retrieved 2018-07-20.
  12. ↑ Fernández, Maikel; Ramírez, Martín; Pérez, Rosa María; Gómez, José Manuel; Cantero, Domingo (June 2013). "Hydrogen sulphide removal from biogas by an anoxic biotrickling filter packed with Pall rings". Chemical Engineering Journal. 225: 456–463. doi:10.1016/j.cej.2013.04.020. ISSN 1385-8947.
  13. ↑ Kolaczkowski, S.T.; Awdry, S.; Le, C.D.; Nuckols, M.L.; Smith, T.; Thomas, D. (2015). "Removal of CO2 from a submersible atmosphere by scrubbing with water—Experiments in a single column". Chemical Engineering Research and Design. 100: 157–169. doi:10.1016/j.cherd.2015.04.035. ISSN 0263-8762.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.