Germany's largest heat storage system is an important component of Berlin's heating revolution. From spring 2023, it will supply a third of Berlin with district heating. In just 34 days, the storage tank was filled with 56 million liters of plant water. The Wiesbaden-based family company Orben took care of the mobile water treatment in accordance with VDI 2035 and AGFW 510 on site.

Germany's largest heat storage tank

In western Berlin, electricity and heat are generated simultaneously. Two structurally identical power plant units went into operation at the end of the 1990s; in 2019, Europe's largest power-to-heat plant with an output of around 60,000 domestic water boilers was connected to the district heating network.

Surplus wind and solar energy is also to be converted into heat soon. For this purpose, a new thermal storage tank was built in Berlin with an impressive 45 meters height, 43 meters diameter and 56 million liters capacity — a volume of around 350,000 bathtubs with a temperature of around 50°C to 98°C in layers.

Local heating water treatment

The operator opted for a mobile heating water treatment system. In doing so, he relied on Wiesbaden-based water specialist Orben, who already has the district heating storage system of Stadtwerke Düsseldorf at 35,000 m³ Wasser has many years of experience with projects of this scale.

Mobile processing — ready for use quickly

Orben is a family company based in Wiesbaden, specializing in products, services and services for heating water and circulating water treatment. Europe's largest regeneration station for ion exchangers is located at the headquarters. The mobile trailers with complete water treatment systems are ready for use within a very short time: Only three days elapsed between the first call to Orben and installation on the power plant site in Berlin.

Water treatment plant in trailer

24 hours after contact, the first configuration of the water treatment system was ready. At the heart of the heating water treatment system was a mobile reverse osmosis system, installed in the Orben Trailer TR-60. This mobile water treatment system is a highly efficient system for generating fully desalinated water (deionized water) with low conductivity and low silicate values, in accordance with at least the requirements of VDI 2035 and AFGW 510. The trailer offers a unit with pretreatment, reverse osmosis, membrane degassing and, if required, regas Cleaning with mixed-bed ion exchangers. The system can also be individually expanded and configured on a project-specific basis.

The construction on site

Despite professional routines, systems of this size often face individual challenges on site. “Every system is different” is often quoted as saying. This is also the case here: The firefighting water removed from the city hydrant was of no tap water quality, which can result in clogged filters and membranes. The existing flow pressure of the fire fighting line was also insufficient to operate the reverse osmosis directly. Therefore, the water was first pumped with a pressure booster pump into a raw water flow tank, which is 70m³ Summarizes. Orben directed the water from this tank into the trailer to the mobile reverse osmosis system installed there. The purified and fully desalinated water was then freed of carbonic acid by membrane degassing; completely desalinated and degassed, the water reliably reduces wear and tear on the approximately 2,000 km long Berlin city heating network.

With a second pressure booster pump, the water then went into the heat storage tank via a downstream VE water tank. Because at a height of 45 meters, the reservoir generates enormous backpressure, which can only be overcome with an additional pressure boosting system.

Filling during ongoing power plant operation

The top priority was that the ongoing operation of the power plant should not be disrupted. Two months were planned for preparation and filling, but 34 days from September to October 2022 were enough. The Orben TR-60 trailer delivered the required amount of heating water around the clock without problems. The interplay between sufficient deionized water, dosing systems and consistent pumping capacity despite enormous backpressure was a challenge that was constantly measured, controlled and regulated. Three Orben employees ensured smooth initial filling on site at all times. The experienced team has safety training for power plant sites, professional equipment and extensive experience. Power plant operations were able to continue running continuously as required; power plant personnel were not retained as desired.

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