a$.$ Find the annual cost if only hot and cold utilities are used to supply all the heating

and cooling for the process streams $($before the heat integration$).$

b$.$ Construct the problem table algorithm for the process with a $T_{\text{m}\text{i}\text{n}}$ of $20C,$ and

find the pinch point, the minimum utility duties and the annual cost for the

utilities after the heat integration.

c$.$ Calculate $\%$ saving $[($Total heat load before integration$-$ Total heat load after

integration$)/$Total heat load before integration$]$ and the minimum HCFR of each

utility streams.

d$.$ Draw the hot and cold end design to achieve a $T_{\text{m}\text{i}\text{n}}$ of $20C.$

e$.$ Construct the new configuration after grid diagram.The following figure shows a process flowsheet in which the reactant stream

$(HCFR=40\frac{kJ}{s}C),$ at $20C,$ are to be heated to $160C$ and fed to a reactor. Since the

reaction is slightly endothermic, the product stream leaves the reactor at $120C.$ After

further heating the reactant stream $(HCFR=60\frac{kJ}{s}C)$ to $260C,$ it is sent to a

distillation column to recover the product. The liquid distillate product

$(HCFR=30\frac{kJ}{s}C)$ from the column is at $180C$ and must be cooled to $20C$ for

storage. The bottom product $(HCFR=50\frac{kJ}{s}C)$ from the column is cooled from $280$ to

$60C.$ Although hot and cold utilities could be used for all the heating and cooling

requirements, there clearly is an opportunity for savings in heat exchange since it is

apparent from the figure that the process streams are, for the most part, within

overlapping temperature ranges. Since the reboiler temperature is too high for heat

exchange with any of the process streams, it becomes an independent heat exchange

problem. A hot oil utility stream available at $320C$ and cooled to $310C$ is to be used

for heating the reboiler, as well as any process heating loads not met by process$-$

process exchange. The cost of the hot oil is $$\frac{2\mathrm{.}25}{?}$ GJ$.$ The condenser temperature is

in a range that could be used to heat some of the process streams; however, for brevity

purposes it will not be included in the present analysis. The cooling utility is cooling

water available at $10C$ with an allowable temperature rise of $10C$ and a cost of

$$\frac{0\mathrm{.}25}{G}J.$