District heating relies on treated water for continuous operation but faces challenges from emergencies, maintenance, and expansion needs. These situations can lead to downtime and revenue loss. Mobile water systems offer flexible solutions, ensuring treated water supply during critical periods. This article explores how these systems support district heating companies in maintaining operations and achieving business goals through reliable water treatment.
By Per-Åke Lindström, Division Sales Manager – Nordics & Baltics, NSI Mobile Water Solutions
Published in Hot Cool, edition no. 8/2024 | ISSN 0904 9681 |
The Importance of Water Treatment in District Heating
Water plays a vital role in district heating systems, acting as the medium that transports heat from generation sources to end-users through extensive distribution networks. Maintaining water quality is crucial, as proper treatment is essential for the system’s overall health and efficiency.
Maximizing System Lifespan through Effective Water Treatment
Adequate water treatment is key to maximizing the lifespan of critical components such as transmission and distribution piping systems, chillers, boilers, and heat exchangers. By preventing corrosion, reducing scale deposits, and minimizing sludge build-up, water treatment improves system efficiency. It also significantly contributes to the longevity and reliability of the entire district heating infrastructure.
Ensuring Continuity of Production
Despite proper treatment, district heating companies still face water-related challenges. These challenges include handling emergencies that require immediate water treatment and maintaining production continuity during planned maintenance of water treatment facilities. Additionally, district heating companies must manage the commissioning of new networks or expansions and respond to seasonal fluctuations in water quality and demand. If not addressed promptly and effectively, such situations can lead to costly downtime.
Mobile Water Systems: A Flexible Solution
Mobile water treatment systems offer a versatile answer to these challenges. They provide emergency response capabilities, temporary replacement during maintenance, support for network commissioning, and scalable capacity for varying demands.
The Evolution of Mobile Water Technology
Mobile water services have come a long way since their inception. Originally, they were simple ion exchange units in trailers. These systems have evolved significantly over time, now encompassing a wide range of technologies. This includes ion exchange units, reverse osmosis systems, membrane degassers, ultrafiltration units, and clarification and filtration systems.
Flexible and efficient Water Treatment with Modular Design
They offer modularity for flexible process configurations, enabling multiple assets to be operated in parallel or series to achieve the required flow rate. These systems facilitate the treatment of diverse water sources, such as town mains, boreholes, rivers, reservoirs, and even wastewater. Additionally, their portability allows them to fit in tight spaces. This evolution has made mobile water systems increasingly valuable in the district heating industry.
Mobile Degassing Units: A Key Technology in District Heating
Mobile degassing units represent a key technology in district heating systems. These advanced membrane degassers efficiently reduce oxygen saturation levels in feed water to as low as <20 parts per billion (ppb). They achieve this without relying on chemical treatments. This innovative approach addresses the treated water needs of district heating systems while offering an environmentally friendly and sustainable solution.
Advantages of Containerized Membrane Systems
These containerized membrane systems offer multiple advantages. Their compact and efficient structure requires little to no maintenance, making them ideal for various settings. Furthermore, the portability of these units enables flexible positioning, optimizing available space and often eliminating the need for permanent infrastructure to house water treatment equipment. This adaptability makes such systems a versatile and efficient choice for district heating applications.
Advanced Membrane for Gas Removal
One example of this technology utilizes specialized membrane contactors for superior gas removal from water. In this system, water flows over hollow fibers while vacuum and nitrogen are simultaneously applied within these fibers. This mechanism allows dissolved gases to pass through the membrane pores, where they are subsequently removed by a vacuum pump. The result is a chemical-free operation with a compact design and minimal maintenance. It also has the impressive capability to treat up to 100 m3/h.
Real-World Applications of Mobile Water Systems
Mobile water services support district heating filling and maintenance activities by providing temporary water treatment for continuous operations. These versatile systems have been successfully deployed in various projects across Europe.
Supporting a district heating provider with RO water during flush and fill operation, Denmark
Key facts:
- Client: District heating provider
- Location: Assens, Denmark
- Population: 6,000
After a 20 km extension of a district heating transmission line, the line needed to be rinsed and filled with approx. 2,500 m³ of RO water. Venting was necessary during filling to remove air from the line. Prefilters also had to be connected to capture particles before heating.
A mobile reverse osmosis, a mobile filtration, a tank, a pump, and a mobile filtration unit were installed. The district heating provider also benefited from O&M and a 24/7 emergency call-out service. The equipment was monitored online.
Figure 1: The process of filling a transmission line with reverse osmosis (RO) water
Engineering Company Builds Large Heat Buffer Tank for District Heating in Germany
Key facts:
- Client: Municipal energy and water utilities provider
- Location: Duisburg, Germany
- Population: Over 500,000
In Germany, a project was completed to fill a 40,000 m³ heat buffer tank for a district heating system. The setup included a mobile reverse osmosis system paired with advanced degassing technology. This configuration produced treated water at a rate of 45 m³/h, achieving conductivity levels below 40 µS/cm and oxygen levels below 50 ppb. The chemical-free production of deoxygenated water was a significant advantage for this application.
Figure 2: The process of removing oxygen through the combination of mobile reverse osmosis system and advanced degassing technology
Figure 3: Containerized mobile degassing technology
District Heating System Fill in the United Kingdom
Key facts:
- Client: Leader in district heating installations and civil engineering projects
- Location: Bristol, England
- Population: Over 470,000
A district heating system fill in the UK demonstrated the flexibility of mobile water treatment solutions. A two-phase approach was employed to fill a 25 m³ district heating system. The first phase involved flushing the system with local water to remove debris and excess chemicals. In the second phase, a combination of pumping and ion exchange systems, along with oxygen removal technology, was utilized. Water was recycled through the system until the required specifications were met, showcasing the adaptability of mobile water treatment systems.
Figure 4: The process of flushing the system with local water to remove debris and excess chemicals
Figure 5: The process of recycling water through the combination of pumping, ion exchange systems, and oxygen removal technology
Temporary Water Treatment Solution for District Heating in the Netherlands
Key facts:
- Client: District heating provider
- Location: Part of the province of North Brabant, the Netherlands
- Population: Over 400,000
In the Netherlands, a power company required a temporary water treatment solution during maintenance. A mobile water treatment system was deployed, treating 50 m³ of water per hour. The system successfully achieved oxygen levels below 10 ppb and maintained operations for 15 weeks, illustrating the reliability and efficiency of mobile water treatment solutions.
Figure 6: Membrane system housed within a fully air-conditioned and insulated 40ft container complete with all the necessary services
The Future of Mobile Water Solutions in District Heating
Mobile water systems play a crucial role in ensuring the reliability and efficiency of district heating networks. They help companies overcome challenges and achieve their goals by providing flexible, on-demand water treatment solutions.
As awareness grows, mobile water solutions are becoming increasingly popular in the district heating industry. They offer several advantages, including improved financial planning through predictable payments, enhanced business continuity, support for resilient water treatment systems, and flexibility for changing needs. They appear an invaluable asset for district heating companies facing today’s and tomorrow’s complex water treatment challenges.
For further information, please contact Per-Åke Lindström: per-ake.lindstrom@nijhuisindustries.com
“Ensuring Water Security for District Heating Companies” was published in Hot Cool, edition no. 8/2024. You can download the article here:
