Sparged reactor

The unit has virtually the same flow sheet (see Fig. 2) as that of methanol carbonylation to acetic acid (qv). Any water present in the methyl acetate feed is destroyed by recycle anhydride. Water impairs the catalyst. Carbonylation occurs in a sparged reactor, fitted with baffles to diminish entrainment of the catalyst-rich Hquid. Carbon monoxide is introduced at about 15—18 MPa from centrifugal, multistage compressors. Gaseous dimethyl ether from the reactor is recycled with the CO and occasional injections of methyl iodide and methyl acetate may be introduced. Near the end of the life of a catalyst charge, additional rhodium chloride, with or without a ligand, can be put into the system to increase anhydride production based on net noble metal introduced. The reaction is exothermic, thus no heat need be added and surplus heat can be recovered as low pressure steam. 

Glasgow LA, Hua J, Yiin TY, Erickson LE (1992) Experimental studies of interfacial phenomena in sparged reactors. In Tatterson GB, Calabrease RV (eds) Process mixing chemical biochemical applications. AIChE Syposium Series 286 Garcia-Briones MA, Brodkey RS, Chalmers JJ (1994) Chem Eng Sci 49 2301 Boulton-Stone JM, Blake JR (1993) J Fluid Mech 254 437... 

Gogoi and Dutta (1996) studied the solid-liquid mass transfer in a three-phase sparged reactor. They derived the following correlation ... 

Mechanically agitated tanks and three-phase sparged reactors Design of the agitator and the sparging system for MSSR... 

K.D.P. Nigam and Schumpe (eds.), Three-Phase Sparged Reactors, Amsterdam, Gordon and Breach Sci. Publ., 1996. 

Mechanically agitated tanks and three-phase sparged reactors 310... 

Bubbling column reactor BCR Also called "gas sparged reactor", it is little used in hydrogenations. Gas is fed, with partial recycling to increase turbulence, at the bottom of a virtually stationary L phase. Mixing is by far less efficient than in STR or JLR. BCR is preferred only when the overall reaction is slow it is an alternative for TBR (S 2.2.6) with better temperature control as a result of higher liquid holdup. 

Recent advances on the Ca-Br cycle were presented in an ANL paper. The original concept for this cycle involved solid phase reactions in a semi-continuous batch operation. The ANL paper reported on experiments that used a direct sparging reactor in the hydrolysis reaction to allow continuous production of HBr which is then electrolytically decomposed to produce hydrogen. The sparging steam was introduced into the molten bath of CaBr2 which yielded HBr in a stable and continuous operation. 

Meier SJ, Hatton TA, Wang DIC (1999), Cell death from bursting bubbles role of cell attachment to rising bubbles in sparged reactors, Biotechnol. Bioeng. 62 468-478. 

Additional information on hydrodynamics of bubble columns and slurry bubble columns can be obtained from Deckwer (Bubble Column Reactors, Wiley, 1992), Nigam and Schumpe (Three-Phase Sparged Reactors, Gordon and Breach, 1996), Ramachandran and Chaudhari (Three-Phase Catalytic Reactors, Gordon and Breach, 1983), and Gianetto and Silveston (Multiphase Chemical Reactors, Hemisphere, 1986). Computational fluid mechanics approaches have also been recently used to estimate mixing and mass-transfer parameters [e.g., see Gupta et al., Chem. Eng. Sci. 56(3) 1117-1125 (2001)]. 

The principle of designing for small gradients is not limited to heat transfer examples. It applies to other thermodynamic gradients as well. For example, sparged reactors with fast reactions benefit from small gas bubbles with a large surface area to promote mass transfer. Under those circumstances minor variations in the partial pressure of reactants give a rapid response in overall reaction rates. 

The culture of cells on microcarriers in sparged reactors requires a conservative approach, including low gas flow rates, small bubble diameter for high oxygen... 

Jadhav S.V., Pangarkar V.G., Paitide-liquid mass tranter in three-phase sparged reactors scale-up effects, Chem. Eng. Sci. 46 (1991) 4, p. 919-926... 

Pandit A.B., Joshi J.B., Mass and heat transjer characteristics of three phase sparged reactors, Chem. Engng. Res. Des. 64 (1986), p. 125-157... 

Precombustion of sulfur from coal by selective oxidation is an important step in coal cleaning, without the need for a postcombustion cleanup step to remove sulfur oxides. This process, known as oxydesulfurization of coal, is a three-phase gas-liquid-solid system. As an example, a sparged reactor wiU be designed to oxydesulfurize 100 tons/day of coal in an aqueous slurry of coal with air. 

Design of Three-Phase Sparged Reactor The following assumptions have been made ... 

Volume 8 THREE-PHASE SPARGED REACTORS edited by K.D.P. Nigam and A. Schumpe... 

A liquid-phase oxidation is carried out in aqueous solution in an agitated, sparged reactor. Batch tests show that the absorption rate decreases as the conversion increases, judging from the change in exit gas composition. The dissolved reactant and the product are nonvolatile, and the vapor pressure of the solution is about 80% that of water. The solution density is 60 Ib/ft. ... 

The bubble column slurry reactor (BCSR) is used mainly for large volume productions, but in a few cases it is also used for specialty chemicals, particularly where a gaseous product is produced and corrosion problems prohibit use of agitated systems. The extent of backmixing can be controlled by using a draft tube. Such sparged reactors are particularly useful for chlorination, sulfonation, and phosgenation reactions. 

Liquid-solid mass transfer, fesLflp (for -4) dp, w, [A], stirring speed (mechanically agitated contactor, turbulent regime) Temperature, gas velocity (sparged reactor, fine particles) 151b... 

Fair, J.R. (1967), Designing gas-sparged reactors, Chemical Engineering, 74(14) 67-74. 

Nocentini, M., Pinelli, D., and MageUi, F. (1998), Analysis of the gas behavior in sparged reactors stirred with multiple Rushton turbines Tentative model validation and scale-up, Industrial Engineering Chemistry Research, 37(4) 1528-1535. 

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