TOTAL SITE HEAT INTEGRATION USING THE UTILITY SYSTEM

Plant sites are normally divided into regions consisting of the individual production processes and the utility system(s). While heat integration within the individual processes has been common for a long time, applications of heat recovery between processes, as well as systematic techniques for this, are only recently being reported. A significant difference when implementing the new approach is that the steam system provides the medium for indirect heat transfer between the processes, so the existing utility lines can be used. In order to minimize the overall cost of such schemes, the fuel consumption and power generation in the utility system need to be considered with the capital cost (mostly heat exchangers) to be invested in the processes. The task requires a proper costing approach for the steam usage, so that the duties and number of levels of steam can be best determined. This paper shows a graphically based procedure for such an optimization which uses the targeting methods of Pinch Technology.