Faculty of Technology, University of Tuzla, Tuzla, Bosnia and Herzegovina, Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA, United States, Faculty of Chemistry and Chemical Engineering, University of Maribor, Maribor, Slovenia, Swiss Federal Institute of Technology Lausanne, Lausanne, Switzerland, Sustainable Process Integration Laboratory—SPIL, NETME Centre, Faculty of Mechanical Engineering, Brno University of Technology—VUT BRNO, Brno, Czechia, CanmetENERGY, Natural Resources Canada, Varennes, QC, Canada, School of Chemical Engineering, Dalian University of Technology, Dalian, China

This work presents the synthesis of heat-integrated water networks (HIWNs) by using mathematical programming. A new superstructure is synthesised by combining a water network and a modified heat exchanger network. Based on the proposed superstructure, a mixed-integer nonlinear programming (MINLP) model is developed. The model is solved by using a one-step solution strategy enabling different initialisations and the generation of multiple solutions, from which the best one is chosen. The results show that the proposed model can be effectively used for solving HIWN problems of different complexities, including large-scale problems.

This work addresses the synthesis of heat-integrated water networks (HIWNs) by using a superstructure optimisation approach. A recently developed mixed-integer nonlinear programming (MINLP) model and an iterative solution strategy are applied in this work to a case study of HIWN. The objective function of the MINLP model is to minimise the network total annualised cost (TAC) comprising operating and investment costs. As there are trade-offs between operating and investment costs, good solutions can be obtained if the TAC is minimised by simultaneously exploring all water and heat integration opportunities within the network. A case study with sensitivity analysis is solved by analysing the impact of freshwater and utility costs on the network design and key performance indicators. The results indicate that in cases of low freshwater cost increased freshwater usage is forced and thus lowering wastewater regeneration/recycling and wastewater treatment cost. Increased freshwater flowrate is related to an increase of HEN investment. The high cost of freshwater could produce solutions with lower freshwater consumption compared to base case depending on utility cost and wastewater treatment cost. However, a decrease in freshwater consumption increases wastewater regeneration costs.

The natural carbon cycle has been disrupted significantly after the industrialisation mainly due to fossil fuel emissions and land use changes. The concentration of CO2 increased from around 280 ppm in preindustrial times to more than 400 pm today, an increase of 2.56∙1011 t CO2 (CDIAC, 2012). Increased concentration of CO2 is related to climate change and its mitigation is in general considered as a main target and also main challenge (Knutti et al., 2016). In order to reduce carbon emissions, several carbon taxation/trading systems have been adopted by various countries, states and companies (Huisingh et al., 2015). Furthermore much of the research have been conducted on carbon capture, storage and utilisation technologies (Cuéllar-Franca and Azapagic, 2015) and also on the development of suitable metrics which are in general based on emissions, prices and costs (Aldy and Pizer, 2015). Several carbon emission reduction opportunities exist, such as increased energy efficiency, use of renewable energy, afforestation and reforestation, carbon utilisation for algae growth, carbon storage and conversion of CO2 to fuels and chemicals. Among the metrics that have been developed are also eco-costs (Hendriks et al., 2012) that stand for the amount of money that would need to be invested in specific technology or environmental strategy to mitigate CO2 emissions, or eco-benefits that represent the amount of money that would be gained from specific technology or environmental strategy due to unburdening the environment (Čuček et al., 2012). This contribution deals with the development of the conceptual framework for obtaining the

In maintaining cooling systems, one of the biggest challenges is to control the corrosion process. Various corrosion inhibitors are often used for this purpose. Which type of corrosion inhibitor will be chosen depends on the material from which the plant has made. The main causes of corrosion in these systems are: pH, dissolved gas, ammonia, temperature and microbiology. In this paper it was studied the efficiency of two multicomponent commercial corrosion inhibitors based on phosphates and one of which containing zinc chloride. For the purposes of research, the pilot plant of open recirculation cooling system is constructed and made of stainless steel (EN 1.4301) and copper (EN 13601). Experiments were performed in a simulated cooling water witch recirculated for 3.5h. For the purpose of accelerating corrosion processes, it was added a corrosion activator (5% NaCl). It was monitored the corrosion rate of the mentioned materials in the cooling water with the corrosion activator, with and without inhibitor. Corrosion rate is determined by using corrosion coupons according standard ASTM D2688 and by analyzing physical-chemical parameters of cooling water. The results showed it was achieved higher protection efficiency for copper and stainless steel by using an inhibitor containing zinc chloride in addition to phosphate.