	 For the distillation column pre-heater, for a shell and tube heat exchanger, the min temperature of the column botttom after preheater that can be achieved is 53 deg C. A double pipe heat exchanger can give upto 45 deg C but does not fit in the layout due to its size. Maintenance would be difficult with this arrangement. Uploading the layout with the double pipe exchanger for your reference. Is a shell and tube with 53 deg C column bottom temperature acceptable?