Toftlund District Heating

Toftlund District Heating issued a comprehensive project for the establishment of a complete wood pellet boiler, electric boiler, and accumulator tank. The present case concerns the wood pellet boiler contract, which Linka Energy bid on and won. As part of the installation of the new pellet boiler, the plant's existing gas boiler will be dismantled and disposed of.

The requirement for the new wood pellet boiler from Toftlund District Heating was to supply the existing absorption heat pump with hot water at 150°C. If the absorption heat pump is wholly or partially out of operation, up to 3,000 kW from the new wood pellet boiler should be able to transfer from the hot water circuit to the district heating circuit at a temperature of 98°C +/-1°C via a new heat exchanger dimensioned for 'the worst possible operational scenario’.

The boiler system, a 3.0 MW Linka H multifuel boiler, is configured for burning wood pellets but can also utilize other fuels such as straw pellets, wood chips, and sunflower seeds/pellets, thanks to its specially designed stoker with two parallel augers. The unique design of the H-boiler with a cylindrical combustion chamber, coupled with Linka's patented combustion technology, ensures the maximum utilization of the fuel.

An economizer has also been installed, serving as a flue gas cooler that transfers energy from the hot flue gas to a cooler medium - in this case, water - which can then be used for preheating or heating. This increases the plant's efficiency since more energy is extracted from the same amount of fuel. The economizer is connected to the flue gas system immediately after the boiler and before the flue gas cyclone.

When heat is “demanded” from the boiler, the firing procedure is initiated: the stoker auger starts and retrieves the required amount of fuel, depending on the heat demand, from the new steel pellet silo via the silo auger and delivers it to the fuel gate, from where it is introduced into the movable step grate inside the boiler.

Inside the boiler's combustion chamber, there is a movable grating to minimize slag formation, and the counterflow combustion system is Linka's patented global system. The flue gas from the boiler passes through an economizer, a multi-cyclone, and a bag filter, which purifies the flue gas, significantly reducing dust emissions before it is released through the existing chimney.

The control of the system is managed through a PLC control system that monitors the plant and sends alarms via the internet and SMS. Additionally, it is possible to monitor the system via smartphones, tablets, and/or PCs.