SUMMARY / RELATED TOPICS

Thomas Marlow

Thomas Marlow was an English cricketer. Marlow was a left-handed batsman, he was born at Leicestershire. Marlow joined the Leicestershire ground staff in 1898, played in the second team, he made his first-class debut against Sussex in the 1900 County Championship at Grace Road. Marlow made fourteen further first-class appearances for the county, the last of which came against Essex in the 1903 County Championship. In his total of fifteen first-class matches, he took 31 wickets at an average of 27.29, with best figures of 6/50. One of two five wicket hauls he took, his best figures came against Hampshire in the 1902 County Championship. A poor tailend batsman, Marlow scored 46 runs at a batting average of 3.28. He died at Leicester, Leicestershire on 13 August 1954. Thomas Marlow at ESPNcricinfo Thomas Marlow at CricketArchive

Structured packing

The term structured packing refers to a range of specially designed materials for use in absorption and distillation columns and chemical reactors. Structured packings consist of thin corrugated metal plates or gauzes arranged in a way that force fluids to take complicated paths through the column, thereby creating a large surface area for contact between different phases. Structured packing is formed from corrugated sheets of perforated embossed metal, plastic or wire gauze; the result is a open honeycomb structure with inclined flow channels giving a high surface area but with low resistance to gas flow. The surface enhancements have been chosen to maximize liquid spreading; these characteristics tend to show significant performance benefits in low pressure and low irrigation rate applications. Structured packings have been established for several decades; the first generation of structured packing arose in the early 1940s. In 1953, a patented packing appeared named Panapak™, made of a wavy-form expanded metal sheet.

The packing was not due to maldistribution and lack of good marketing. The second generation appeared at the end of 1950’s, with efficient wire mesh packings, such as Goodloe ™, Hyperfil ™ and Koch-Sulzer; until the 1970s, due to their low pressure drop per theoretical stage, those packings were the most used in vacuum distillation. However, high cost, low capacity and high sensitivity to solids have prevented wider utilization of wire mesh packings. Corrugated structured packings, introduced by Sulzer by the end of the 1970s, marked the third generation of structured packed columns; these packings offer high capacity, lower cost, less sensitivity to solids, while keeping a high performance. Popularity of the packings grew in the 1980s for revamps in oil and petrochemical plants; these structured packings, made of corrugated metal sheets, had their surfaces treated, chemically or mechanically, in order to enhance their wettability. The packings' wetted area increased, improving performance. In 1994, a new geometry was developed, called Optiflow.

In 1999, an improved structure of corrugated sheet packings, the MellapackPlus, was developed based on CFD simulations and experiment. This new structure, compared with conventional Mellapak, has a lowered pressure drop and maximum useful capacity could be extended up to 50%. Structured packing is manufactured in a wide range of sizes by varying the crimp altitude. Packing surface ranges from 50 m²/m³ to 750 m²/m³. Typical applications include vacuum and atmospheric crude oil fractionators, FCC main fractionators and TEG contactors; the separation of mono-, di- and triethanolamine, conducted under vacuum, may utilize structured packing, owing to its low pressure drop. Tall oil fractionation, the process of separating fatty acids from rosin acids and pitch obtained as a by-product of the Kraft process of wood pulp manufacture utilizes structured packing; the packing additionally finds use in the manufacture of styrene monomer and the dehydration of glycol in natural gas processing. Structured packing finds use in the equipment/processes below: Air separation Cyclohexanone/Cyclohexanol separation Xylene splitters CO2 absorbers H2S absorbers Ethylene oxide absorbers Acrylonitrile absorbers Oleo Chemicals Fine Chemicals Structured packing offers the following advantages as compared to the use of random packing and trays: Lower pressure drop Higher efficiency Higher capacity Reduced liquid hold-up Structured packing offers the following disadvantages as compared to the use of random packing and trays: Cost Greater sensitivity to maldistribution Packed bed Raschig ring Dixon rings Random column packing