A multiple-effect evaporator is an apparatus for efficiently by means of the heat from steam to evaporate water. Water is boiled in a sequence of vessels, each held at a lower pressure than the last. Because the boiling temperature of water decreases as pressure decreases, the vapour boiled off in one vessel can be used to heat the next. and only the first vessel requires an external source of heat. While in theory. evaporators may be built with an arbitrarily large number of stages, evaporators with more than four stages are rarely practical except in systems where the liquor is the desired product such as in chemical recovery systems where up to seven effects are used. Multiple effect evaporation commonly uses sensible heat in the condensate to preheat liquor to be flashed. In practice the design liguid flow paths can be somewhat complicated in order to extract the most recoverable heat and to obtain the highest evaporation rates from the equipment. The evaporator is used to remove the solvent from the solution. In the four stage evaporation system used in sugar cane industries, a 50% by mass sugar solution is concentrated to by 65% by evaporating an equal amount of water in each of four stages. With total input of 50,0XX lb/h, a product stream of 35,0XX lb/h is produced.
Draw the block flow diagram?
Write the general material balance for the system?
Determine the compositions of intermediate stream?
Whether the mass flow rate of each stream can be calculated? If yes or no, justify your answer.
Perform the Degree freedom of analysis of overall system and individual units?
Write the strategy to solve the problem.
A multiple-effect evaporator is an apparatus for efficiently by means of the heat from steam to evaporate water. Water is boiled in a sequence of vessels, each held at a lower pressure than the last. Because the boiling temperature of water decreases as pressure decreases, the vapour boiled off in one vessel can be used to heat the next. and only the first vessel requires an external source of heat. While in theory. evaporators may be built with an arbitrarily large number of stages, evaporators with more than four stages are rarely practical except in systems where the liquor is the desired product such as in chemical recovery systems where up to seven effects are used. Multiple effect evaporation commonly uses sensible heat in the condensate to preheat liquor to be flashed. In practice the design liguid flow paths can be somewhat complicated in order to extract the most recoverable heat and to obtain the highest evaporation rates from the equipment. The evaporator is used to remove the solvent from the solution. In the four stage evaporation system used in sugar cane industries, a 50% by mass sugar solution is concentrated to by 65% by evaporating an equal amount of water in each of four stages. With total input of 50,0XX lb/h, a product stream of 35,0XX lb/h is produced.
Draw the block flow diagram?
Write the general material balance for the system?
Determine the compositions of intermediate stream?
Whether the mass flow rate of each stream can be calculated? If yes or no, justify your answer.
Perform the Degree freedom of analysis of overall system and individual units?
Write the strategy to solve the problem.
