Energy Efficient Pumping Solutions for Solar District Heating

A key component in solar district heating is obviously the solar panels, but energy efficient pumps are another area that should be in focus, and this is where DESMI comes into the picture.

DESMI e.g. supplied energy efficient, in-line, vertical NSL centrifugal pumps for one of the world’s largest solar heating plants: The Dronninglung Solar Thermal (District Heating) Plant in the northern part of Denmark.

This particular solar district heating plant has a water thermal storage reservoir of 60,000 m³2,982 solar panels with a total surface area of 401,225 ft², which is equal to more than five football pitches.

DESMI pumps are used for circulation applications in primary as well as secondary areas, and we also supply shunt pumps.

Typically these types of pumps have energy efficiency levels well above 90%. With proper use and maintenance it is not unusual that these pumps can perform over the entire lifespan of such a solar plant – typically 25 years – contributing to the sound economy of the project.

Furthermore, our vertical pumps save around 50% important floor space compared to horizontal pump installations, which means that the plant can be more compact – which again helps to save costs.

District heating in Denmark (and in several other countries) involved distribution of hot water below 212°F. For such applications DESMI has developed the so-called “Spacer Design”, which results in very easy maintenance since the design allows the motor to stay onto the pump during service – and the pump can remain installed in the pipework, while it is being serviced. This design can be supplied for both vertical AND horizontal, in-line as well as end-suction executions, flow capacities up to 17,612 gallons per minute and with pressure ratings up to PN25. For applications with temperatures about 212°F, a different design is required and in this way the DESMI compact version pumps can manage media temperatures up to 284°F.

Besides the pump installations at Dronninglund Solar District Heating Plant, DESMI’s versatile range of NSL Centrifugal pumps represent high efficiency, low NPSH values, easy installation, and low maintenance. The NSL series is widely used within different markets and applications because the pump is designed for mounting with electric motors with different international flange dimensions, among a host of other great qualities.

Within the Marine Industry the pumps are suitable for:

Fresh and seawater cooling pumps
Bilge and ballast pumps
Fire-fighting
General Service pumps
Transport of slightly aggressive liquids with low viscosity such as diesel and lubricating oils.

Within the industrial and utility applications: