Integration of desalination with cold–heat–power production in the agro-food industry

Several configurations of polygeneration systems, conceived for a dairy industry requiring cold, heat, power and water for its operation, are presented. For these systems, a single fuel is used to produce cold, steam (heat), electricity and water from a combined cycle integrated and optimized with heaters, absorption units and desalination plants. The proposed systems are the result of minimizing a multi-objective function of energy (cold, heat and power) and water consumption in order to reach a more efficient and sustainable management of the installation. The industry covers its internal demand for energy and water and reaches important overall energy savings thanks to the integration of all the systems. Different configurations are analyzed in which, depending on the required demands, thermal desalination or reverse osmosis are considered. An economic analysis was also performed. The overall system was modeled by means of data provided by manufacturers and also by means of efficiency curves available in the literature.

The most important message is the need and advantage of minimizing together, in a multiobjective function, the water and energy used in a system in order to reduce the consumption of natural resources. In combined plants producing water and energy, it is very common to analyze the system as two separate systems. Uche [8] has proved that the most appropriate approach encompasses the analysis of both systems — the energy plant and the desalination unit — as a whole system. In this paper this concept was applied to a polygeneration system producing energy (cold, heat, power) and water from a single fuel. This idea could be extended to the minimization of all natural resources, which are finite, used in various industrial processes.