Benzene from a stream of N is to be and separated in an absorption column followed...

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Benzene from a stream of N₂ is to be and separated in an absorption column followed by steam stripping to recover the hydrocarbon. The feed (100 kmol/h) enters the absorption column at 25°C and is 90% saturated with benzene. Not more than 2.5% of the feed benzene should leave the column. The feed solvent has 0.007 mole benzene per mole of 'pure' solvent (mol. wt. = 240). The loaded solvent leaving the absorber has 0.3 mole benzene per mole of pure solvent. The solution is heated and fed to the stripping tower to reduce the benzene content to 0.007 mole ratio so that the lean liquid can be cooled and recycled to the absorption. The steam rate used is 1.5 times the minimum. Both the towers operate at atmospheric pressure. The absorption tower operates at 25°C and the stripping tower at 110°C. The equilibrium data at 25°C are given below. X Y 0.04 0.011 0.08 0.0215 0.12 0.032 0.16 0.040 0.20 0.051 0.24 0.060 The Raoult's law may be used to determine the equilibrium relationship at the stripping temperature of 110°C. Vapour pressure of benzene can be calculated from the Antoine equation, In P = 17.5818 (3867/T); P = vapour pressure in mm Hg: T = temperature, K. (a) Calculate the liquid rate to the absorber. (b) Determine the number of ideal trays required for absorption. (c) What is the minimum possible steam rate? (d) Determine the number of ideal trays in the stripping column. (e) How many real trays are required for stripping if the Murphree plate efficiency is 50%? Benzene from a stream of N₂ is to be and separated in an absorption column followed by steam stripping to recover the hydrocarbon. The feed (100 kmol/h) enters the absorption column at 25°C and is 90% saturated with benzene. Not more than 2.5% of the feed benzene should leave the column. The feed solvent has 0.007 mole benzene per mole of 'pure' solvent (mol. wt. = 240). The loaded solvent leaving the absorber has 0.3 mole benzene per mole of pure solvent. The solution is heated and fed to the stripping tower to reduce the benzene content to 0.007 mole ratio so that the lean liquid can be cooled and recycled to the absorption. The steam rate used is 1.5 times the minimum. Both the towers operate at atmospheric pressure. The absorption tower operates at 25°C and the stripping tower at 110°C. The equilibrium data at 25°C are given below. X Y 0.04 0.011 0.08 0.0215 0.12 0.032 0.16 0.040 0.20 0.051 0.24 0.060 The Raoult's law may be used to determine the equilibrium relationship at the stripping temperature of 110°C. Vapour pressure of benzene can be calculated from the Antoine equation, In P = 17.5818 (3867/T); P = vapour pressure in mm Hg: T = temperature, K. (a) Calculate the liquid rate to the absorber. (b) Determine the number of ideal trays required for absorption. (c) What is the minimum possible steam rate? (d) Determine the number of ideal trays in the stripping column. (e) How many real trays are required for stripping if the Murphree plate efficiency is 50%?

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a To calculate the liquid rate to the absorber we first need to determine the amount of benzene ente... View the full answer