In Example 12.7, an existing exchanger is used to transfer sensible heat between toluene and styrene streams. A minimum approach temperature of \(31.3^{\circ} \mathrm{F}\) is achieved. Design a new shell-and-tube heat exchanger for a \(10^{\circ} \mathrm{F}\) minimum approach temperature.

Data From Example 12.7:-

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An existing 2-8 shell-and-tube heat exchanger in a single shell (equiv- alent to two shells in series with 4 tube passes in each shell) is to be used to transfer heat to a toluene feed stream from a styrene product stream. The toluene enters the exchanger on the tube side at a flow rate of 125,000 lb/hr at 100F and 90 psia. The styrene enters on the shell side at a flow rate of 150,000 lb/hr at 300F and 50 psia. The exchanger shell and tubes are carbon steel. The shell has an inside diameter of 39 in. and contains 1,024 3/4-in., 14 BWG, 16-ft-long tubes on a 1-in. square pitch. Twenty-two segmental baffles are used with a baffle cut of 25%. Shell inlet and outlet nozzles are 6.0-in., schedule 40 pipe, and tube-side inlet and outlet nozzles are 4-in., schedule 40 pipe. Fouling factors are estimated to be 0.002 (hr-ft-F)/Btu on each side. Deter- mine the exit temperatures of the two streams, the heat duty, and the pressure drops.