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Tham khảo tài liệu 'arnold, k. (1999). design of gas-handling systems and facilities (2nd ed.) episode 2 part 1', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 236 Design of Gas-Handling S stems inti Facilities Table 8-4 Properties of Solid Desiccants Desiccant Bulk Density lb fp Specific Heat Bhj lb F Normal Sizes Used Design Adsorptive Capacity WT Regeneration Temperature F Activated Alumina 51 0.24 in.-8 mesh 7 350-600 Mobi 1 St R Beads 49 0.25 4-8 mesh 6 300 500 Fluorite 50 0.24 4-8 mesh 4-5 350 Alumina Gel H-151 52 0.24 rS- A inch 7 350-850 Silica Gel 45 0.22 4-8 mesh 7 350 Molecular Sieves 4A 45 0.25 inch 14 450-550 Sim rec API. desiccants are interchangeable and the equipment designed for one desiccant can often be operated effectively with another product. Table 8-4 illustrates the most common desiccants used for gas dehydration and some conservative parameters to use for initial design. Desiccant suppliers information should be consulted for detail design. All desiccants exhibit a decrease in capacity design loading with increase in temperature. Molecular sieves tend to be the less severely affected and aluminas the most affected by temperature. Aluminas and molecular sieves act as a catalyst with H2S to form COS. When the bed is regenerated sulfur remains and plugs up the spaces. Liquid hydrocarbons also present a plugging problem to all desiccants but molecular sieves are less susceptible to contamination with liquid hydrocarbons. Silica gels will shatter in the presence of free water and are chemically attacked by many corrosion inhibitors. The chemical attack permanently destroys the silica gels. The other desiccants are not as sensitive to free water and are not chemically attacked by most corrosion inhibitors. However unless the regeneration temperature is high enough to desorb the inhibitor the inhibitor may adhere to the desiccants and possibly cause coking. The alumina gels activated aluminas and molecular sieves arc ail chemically attacked by strong mineral acids and their adsorptive capacity Gas Dehydration 237 will quickly decline. Special acid resistant molecular sieve desiccants are available. .
