Research On Water-Using Network For Batch Process With Multi-Contaminant

The scarcity and contamination of the water result in water resource crisis around the world. Economically using water and improving the utilization efficiency of water resource is an important way of solving the crisis. Process industry has consumed a large amount of fresh water and discharged a lot of waste water. Reducing those fresh water and waste water is a great matter of urgency. The aggregation of all the water-using processes in an enterprise is a water-using network. Water reuse rate is maximized by arranging water using operation and adding regeneration appropriately. So it is very worthy of research on water-using network which is a solution of water resource crisis. Water-using network synthesis has been studied since twenty years before. Many scholars around the world presented a great number of valuable ideas and methods. But most of these methods are only applicable to continuous processes. Only batch processes with single contaminant is researched. Due to the dynamic characteristic of batch processes and the complexity of multi-contaminant processes, there are few of work on batch processes with multi- contaminant which is more valuable and practicable. Basing on the existing achievements which is about batch processes with single contaminant, approaching from the characteristics of variable water-using networks and taking the mathematical programming as a tool, the author makes a systematic and deep research on the determination of the minimum fresh water consumption of the reusing process of batch chemical process with multi- contaminant, and design water-using network with regeneration. The main contents are extracted and listed as below:(1) An optimization strategy is approached based on sequential-operation model. The time limitation to reuse is eliminated by connecting a tank to each operation unit in batch processes, so the superstructure of multi-contaminate water-using network for batch is established, and then the mathematical model of the superstructure is presented, which is a series of non-linear programming equations with inner-exterior two layers, simplified the superstructure by water source priority rules, then solved it by LINGO. Finally, the optimize water using network is established.(2) This paper approaches an optimization strategy based on the optimal network. The optimal network of pseudo-batch process is a target network, and then the water network based on the target network is optimized. Lastly, water network for batch process is found in the least cycles.(3) The water-using network with regeneration is designed by two-segment design method. The target network of pseudo-batch process is found by using this design method, and then the optimal water network based on the target network is obtained.