Evaporation units are commonly used to increase the concentration of salt in a solution. Because dissolved salts have such high melting and boiling points, they will not evaporate in the evaporation unit. However, highly volatile components in the solution will usually evaporate along with the primary solvent.

The feed to an evaporation unit consists of a mixture of a dissolved solid, water, and a small amount of volatile organic compounds $($VOCs$).$ The evaporation unit is designed to increase the concentration of the solid in solution from $20\%$ mass to $68\%$ mass. Research shows the expected concentration of the evaporated stream will be $1$ kg VOCs per $19$ kg water. The evaporation unit is designed to remove all VOCs from the concentrated stream.

a$)$ Assume the total flow rate of the evaporated stream is $1000$ kg$/$h$,$ then draw and fully label a flow chart for this process $($included all knowns and unknowns$).$

b$)$ Perform a degree of freedom analysis.

c$)$ Calculate the composition of the exiting vapor stream $($mass fractions$).$

d$)$ Calculate the total flow rate of feed and the concentrated salt solution $($kg$/$h$).$

e$)$ Calculate the mass fraction of water in the feed.