23-Danfoss Cooling towers manufacturer gas fired boilers News 140607

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Danfoss - Drives boost energy savings at Natural History Museum

Initially, the South Kensington Museum Estate Centralised Boiler House, installed in 1952 in the basement of the Natural History Museum, used to distribute heat to a number of adjacent museums and colleges. In recent years, especially when the Science Museum and Imperial College installed CHP systems, it became clear that the NHM’s boiler house was over-large, inefficient and in need of refurbishment.
Now, Vital Energi of Bolton are to guarantee to save the Natural History Museum (NHM) £500,000 and 1800 tonnes of CO2 every year over the next fifeteen years with their first Energy Performance Contract. This £12 million project will involve the finance, design, supply, installation and commissioning of the necessary plant and equipment to provide tri-generation of electrical power and heating services to both the Natural History Museum and the Victoria and Albert Museum next door.
The work involved the removal of two of the boilers and in their place the installation of a 1.8MWe gas fired CHP engine, two 750KW absorption chillers to utilise CHP waste heat for heating and cooling purposes and the installation of two new cooling towers. Vital Energi will also be responsible for the operation and maintenance of the energy centre over the next fifteen years.
In a complex the size of the NHM, it’s inevitable that the various air and water circuits and sub-circuits will require to be balanced and some method of control provided to maintain that balance, otherwise the hot water and cooled air would not be delivered to the appropriate parts of the building. Traditionally, proportional balancing was achieved using valves in the water circuits and dampers in the air ducts but this form of control is, at best, sloppy and inefficient.
Today, the use of valves has increasingly given way to accurate, more efficient flow control by varying the speeds of the fans and pumps delivering the air and water throughout the building. As energy costs have risen, so the cost per kW of VSDs has steadily reduced and the economic case for VSD control has become undeniable.
It’s for that reason that nowhere on this extensive system has Vital Energi used regulating valves but instead has installed Grundfos variable speed pumps and 16 Danfoss VSDs between 2.2kW and 30kW on all the primary and secondary water circuits, under the control of the museum’s existing BMS. As Mr Wonsbek explained, “there’s little point in refurbishing a system to improve its efficiency then to install control valves which would merely drag the overall efficiency down again. Even where there is no need for continuous variable flow control, we have used variable speed pumps to tune the system initially and these will then run fixed at that reduced speed set point.”

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