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General contractor for replacement of line P8 at Stockholm Högdalen


After the contract had been ceremoniously signed at Stockholm Exergi's headquarters on 20/03/2018, the customer officially authorized the delivery of the new waste combustion line P8 by issuing the notice to proceed on 18/06/2018.

MARTIN is the general contractor for the delivery of the combustion system, steam boiler, flue gas cleaning system and additional ancillary lots. The customer, Stockholm Exergi, is a joint venture between the city of Stockholm and Fortum in which the two partners hold equal shares.

At Högdalen Stockholm Exergi operates a waste-to-energy plant designed to generate district heat and electricity. In addition to other lines, our customer also operates waste combustion line P3, which was supplied by MARTIN and has been reliably operating for many years. The new line P8 will replace the two oldest lines of the plant.

The new line will be equipped with a 3-run reverse-acting grate Vario with a total width of 6.32 m. It will be designed for a gross heat release of 54.1 MW and a thermal treatment capacity of 20.5 t/h of waste. The superheated steam produced (400 °C and 36 bar) will be converted into electricity in a counter-pressure steam turbine. The residual energy contained in the exhaust steam will then be fed into Stockholm's district heating network.

The particular challenge of this order is that the new line has to be fitted into the limited space available on site. The existing plant must continue to operate throughout the construction phase because operational reliability of the district heating network is of utmost importance.

The planning and procurement phase is already in progress and installation of the main components will begin in March 2019. Start-up will commence in June 2020 and handover to the customer is scheduled for March 2021.