(341v) Synthesis and Design of Sustainable Integrated Process Water Treatment and Energy Supply Networks

Chemical processes convert selected raw materials to desired chemical products, while requiring also utilities such as water and energy and produce wastes, thereby effecting the environment negatively. Usually the process synthesis and/or design problem is solved considering the cost of energy and water but without considering their availability limits or their sources. Different sources and generation processes of water and energy may cause different investment costs, operating costs, carbon emissions and pollutant chemical emissions, which should be optimized (minimized) along with the production process.

In this paper, we propose the concept of sustainable synthesis, design and innovation of integrated processes that combines water and energy supply networks together with the overall objective to achieve zero or negative carbon emissions as well as wastes. All potential available energy sources for power and heat generation processes are integrated into a consolidated energy supply network in the form of a multi-level superstructure. Similarly, all possible water sources and treatment technologies, including waste water recycling, are integrated into a water network. For identified target products, all existing and potential processing routes are integrated into a superstructure representing a process network, which also includes carbon dioxide capture and utilization processes. They lead to the formation of a consolidated optimization problem, which represents multiple networks at different scales and includes environmental impacts as constraints.

The architecture of a model-data based framework combining the three networks, that is, the process, energy and water supply networks is presented. First, a superstructure is developed that combines the power generation network, the water network and the chemical process network for converting specified raw materials, including captured carbon dioxide, to specified products. The parameters of the associated mathematical model are identified through data collection from various sources. The sustainable synthesis-design problem is solved step by step using a decomposition-based solution strategy and leads to the design of a totally integrated and sustainable process with high benefits and low carbon emissions and pollutant emissions.

The applicability of the framework and solution steps are demonstrated through a realistic conceptual case study under different scenarios. The xylitol production process is used as a case study. The energy supply network is subdivided into power generation and heat generation sub-networks while the water network is subdivided to external water supply sub-network and wastewater treatment and recycling sub-network. Chemical production process and wastewater treatment process are designed in detail while for other networks the main focus has been the optimization of energy and water resources. The results show that the multi-network synthesis and design method is not only able to obtain solutions that give higher economic benefits than conventional design methods, while satisfying also the environmental constraints and ensuring optimal design of available energy and water sources.