Water recovery from waste heat effluents
The French and European industries face a dual environmental challenge: decarbonising thermal processes that remain heavily reliant on heat generated from fossil fuels, and reducing water consumption, which is severely limited by climate conditions and regulatory requirements.
Cross-analysing industrial water withdrawals and sources of excess heat reveals that several sectors are at the intersection of these two challenges. The Chemical and Food Processing sectors account for over 50% of sources of excess heat and industrial water abstraction. These are closely followed by the Pulp and Paper, Non-metallic Materials (glass, cement, terracotta, etc.) and Metallurgy sectors, which represent around 10% of each category.
In this context, and given the observation that many sources of excess heat also contain water, the central question of this study emerged: under what circumstances is the joint recovery of heat and water a viable option? This central question raises several sub-issues relating to the feasibility, profitability and competitiveness of these solutions in the industrial sector.
- Firstly, the study aims to analyse the building blocks required to implement this type of project (e.g. equipment, studies and technologies) in order to identify technical, technological and regulatory obstacles, barriers and opportunities.
- The study then examines the key factors that determine the environmental and financial impact of projects.
Three sets of factors that significantly influence profitability are identified, and favourable ranges for each are outlined. These factors may include contextual elements such as the number of annual operating hours, the reference price of heat, or local water pressure. They may also include factors related to the type of excess heat stream targeted, such as temperature and water content. - Drawing on the conclusions of the preceding sections, the study proposes an analysis and quantification of the potential of industrial sectors and sub-sectors
To illustrate and challenge the results, the study presents case studies of applications, drawing partly on previous cases. The analysed cases confirm the technical feasibility of combined heat and water recovery in the relevant sectors.
The LIFE ZEUS project, implemented by MONIN (a French syrup manufacturer) at its Bourges site, demonstrates the industrial feasibility of water recycling in a Food Processing context. The expected water savings exceed 60% of the site’s annual consumption by reusing all 38,000 m³ of water discharged each year.
