A. The Design of Heat Exchanger Networks - A Simple Example

Figure 1 shows a simple flowsheet. There is heat integration, observing a minimum temperature driving force for the heat exchangers (ΔT_min) of 10 K, as shown in the inset relating to one of the heat exchangers. Operability and control considerations have led to the use of utilities in the column reboiler and condenser. The overall steam demand (excluding the reboiler) is 2,040 kW.

We would like to know whether 2,040 kW of hot utility is truly necessary. To achieve improvements, the designer might try a lower ΔT_min, use equipment optimisation, or try a different network integration scheme.

Figure 2 shows an alternative network design. The same value for ΔT_min has been used, that is 10 K, but the network configuration has been changed, showing much improved energy performance, requiring only 1,200 kW of steam.