Water savings from heat integration

The overall balance gives an excess of 1500 kW, so the problem does not require hot utility. There is need only for cold utility (cooling water). Thus, feed preheating may be covered exclusively by the exothermic reaction and save a significant amount of energy. However, a furnace is necessary before reactor to ensure constant temperature. The reactor outlet is quenched at 620 °C. Assume that the furnace has to preheat the reaction mixture from 520 °C to a reaction temperature of 630 °C. By simulation we find a duty of 3800 kW. The new stream population for heat integration becomes ... 

One option to overcome the decrease in solvent temperature and thns desorption driving force is improved process design. As an example, the MGD section will consist of several modules in series and in parallel. Intermediate heating between the modules can be applied to retain driving force. Moreover, when the temperature of the solvent is increased along the flow direction, heat integration of the evaporated water from the next modnle can be applied to heat the solvent. In this way, even more energy, and, therefore, operational costs, can be saved. 

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