A caustic solution entering the shell$-$tube evaporator at $10000$kg$/$hr with a temperature of $1000$C is concentrated in a single effect continuous evaporator into a concentrate of $40\%$ sugar solution. The concentrated stream leaves the evaporator at $6000$ kg$/$hr$.$ The vapour space inside the evaporator is at $-30$kPa $($g$).$ Steam is supplied at $300$kPa $($abs$)$ into the shell side. The overall heat transfer coefficient $($HTC$)$ is $1704$W$/$m$2.$K$.$