2) with neat diagram explain the working and construction of calandria type evaporator.

3)give the method of determination of safe pressure against elastic and plastic failure.

(8) Glauber's salt, Na2SO410H2O is to be produced in a Swenson-Walker crystalliser by cooling to 290k a solution of anhydrous Na2SO4 which saturates between 300k and 290K. If cooling water enters and leaves the unit at 280K and 290k respectively and evaporation is negligible, how many section of crystalliser each 3m long will be required to process 0.25kg/s of the product? The solubilities of anhydrous Na2SO4 in water are 40 and 14kg/100kg water at 300k and 290k respectively, the mean heat capacity of the liquor is 3.8kJ/kgk and the heat of crystallisation is 230kJ/kg for the crystalliser, the available heat transfer area is 3m2/m length, the overall coefficient of heat transfer is 0.15kW/m2k and the molecular masses are Na2SO410H2O=322kg/kmol and Na2SO4=142kg/kmol