1. The problem statement, all variables and given/known data Here's a quick sketch of the problem: http://prntscr.com/15ltr5 Essentially, Sugar Solution enters the first evaporator at 65°C and the water is boiled (to 100°C) so that a sugar concentrate comes out (bottom of evaporator) and saturated steam leaves the evaporator through the top and heats the next evaporator. This process continues for the remaining 2 evaporators. Therefore, in order for the saturated steam to boil the sucrose solution in the next evaporator, energy is lost thus, more heat is required, OR, a drop in pressure is necessary. This is my understanding of information given to me... here's the original: http://prntscr.com/15lub4 I'm suppose to calculate: Amount of sugar concentration leaving each of the evaporators also... What is the reduction in steam usage per kg of total water evaporated for the four evaporators in series compared to one evaporator ? 2. Relevant equations Really no idea. 3. The attempt at a solution I thought you could use Guy Lussac's Law, however, I'm not too sure about this. P1/T1 = P2/T2 Thus, 1 atm, 0.65atm, 0.4225atm and 0.274625atm, this logic however, seems massively flawed. I'm seriously stumped!