Abstract
In the production process of viscose staple fiber, a large amount of freshwater, steam and desalinated water will be consumed, and a large amount of acidic and alkaline wastewater will be generated, bringing great pressure on water resource and environmental protection. In this paper, the water using system of a viscose staple fiber plant in northwestern China is studied. The key constraints for water using in this system are pH, oxygen demand (COD) and suspended solid (SS). Since pH and COD are non-conserved quantities, their constraints are property-based. So, the optimization of the water network needs to be carried out from both conventional water system integration and property integration. In this paper, the Mathematical Programming method is used to solve the optimization problem. By analyzing the various constraints and taking the corresponding integration methods, the mathematical model is constructed to target the minimum freshwater flowrate, the minimum regenerated water flowrate and relevant parameters. The optimized network can reduce the freshwater consumption 93.1 m³/h and the wastewater discharge 131 m³/h, achieving obvious water-saving and emission reduction effects.
