New Methods for Process Integration: New Process Integration Methods for Heat-saving Retrofit Projects in Industrial Systems

New graphical methods have been developed for HEN retrofit, release of usable excess heat, and placement of supply tanks in HWWS systems. In addition, the matrix method for HEN retrofit has been developed further. Using the advanced composite curves together with the matrix method in HEN retrofit gives new insights into which units should be chosen for retrofit. Calculations have shown that heaters and coolers placed close to the pinch are often cheaper by a factor of two or more to retrofit. A method to show the potential for releasing usable excess heat at high temperature levels (but still below the pinch) has been developed. Case studies demonstrate that much of the potential can also be achieved with acceptable PBPs. Another method, to be used in HWWS systems has also been developed. It shows the potential usable excess heat versus temperature in this subsystem for a user- defined number of supply tanks and temperature difference. A new optimisation routine has been developed and implemented into the matrix method. This method uses a recursive branch and bound algorithm to explore all relevant paths in the retrofit task.