It appears to be a rather dynamic field, with new method and application areas emerging constantly. The Process Integration is defined as systematic and general methods for designing integrated production systems, ranging from individual processes to total sites, with special emphasis on the efficient use of energy and reducing environmental effects. This definition brings Process Integration very close to Process Synthesis, which is another systems oriented technology. Process Integration and synthesis belongs to process systems engineering. Process Integration has evolved from a heat recovery methodology in the 80's to become what a number of leading industrial companies in 90's regarded as a major strategic design and planning technology. With this technology, it is possible to significantly reduce the operating cost of existing plants, while new processes often can be designed with reduction in both investment cost and operating cost. (from nptel.ac.in)