Feature : Distri ct energy A practical legacy from the Soviet era, industrial buildings were built with expansion in mind nerijus rinkevičius Vice-Director Enerstena Research & Development Centre. (1) The automatic pneumatic soot blowers keep the boiler tubes surfaces clean. (2) Woodchips from the two storage bunkers are automatically metered into the boiler house drag-conveyor by moving floor and spirial screw. (3) Two 12 MW furnaces Inside the spacious boiler house. (4) The plant is also where fresh water from the river is drawn and purified to top-up the district heating network. Arionex is a Swiss water engineering company that has representation in Kaunas. Bioenergy International No 81, 5-2015 9 produced over 21 percent of the total heat supplied to all networks, up 80 GWh on 2012, purchasing just over 1 TWh heat from eight independent producers including KCHP, still the dominant supplier. Kauno Energija more than doubled its heat share to the integrated city network, from just over 6 percent in 2012 to 16 percent in 2014. Furthermore although fossil gas is still the main fuel, its share dropped to 71 percent having been replaced by cheaper solid biomass and a fraction of biogas and peat. Other benefits include a reduction in fuel and electricity consumption per MWh heat produced, a reduction in heat losses in the distribution networks and an over 11 percent reduction in the amount of water needed to supplement the network. More GWh of their own heat was supplied but at a lower rate. The decrease in the comparable expenses has led independent producers of heat, from which the company buys and distributes the heat to the consumers, to reduce the cost of sold heat. All of these add up to almost 27 percent reduction of operating costs compared to 2013, increasing the profitability of the company despite a 22 percent drop in revenue from heat sales. Local biomass technology One of the key suppliers to the various biomass boiler projects is a local company, Kaunas based combustion technology specialist Enerstena Group. Founded in 2002 the company has grown into a major developer and manufacturer of biomass combustion and ancillary solutions. Deliveries include turnkey plants to some of the independent heat producers in Kaunas but also to industrial heat and steam applications in countries like Latvia and France. One of the larger installations for Kauno Energija was the Petrašiūnai power plant conversion that started in 2013. Built on the banks of the Nemunas River and commissioned in 1930, it is one of the oldest power plants still operating in Lithuania. It is, reportedly, the first cogeneration in the country - in 1947 steam from the plant was used for space heating in neighbouring industrial buildings. Run on fossil gas the 60.5 MW electric capacity Petrašiūnai plant has in more recent years been the main reserve heat generation source for the Kaunas integrated heat supply network. It is also the point where fresh water from the river is drawn to top up the network. Award-winning technology At Petrašiūnai, Enerstena first installed a fluegas condenser for the remaining 100 MW gas boiler. This was followed by the installation of two 12 MW woodchip fired hot water boilers with a 6 MW condensing economiser. – A practical legacy from the Soviet era, industrial buildings were built with future expansion in mind so there is plenty of space to maneuver, commented Nerijus Rinkevičius, Vice Director, Enerstena Research & Development Center, during a visit to the plant pointing out where the two boiler units were literally dropped into place through a hole in the wall. Enerstena also provided the boiler infeed, woodchip fuel receiving bunkers and renovated a railway spur. – As far as I know this is the only biomass heat plant in the country that can receive and unload woodchips by rail, said Rinkevičius. Designed by the R&D arm of Enerstena in cooperation with the Kaunas University of Technology, the combustion furnace has an oblique moving grate with a water-cooled frame and it is designed to handle biomass with moisture content of up to 55 percent. To ensure complete combustion the process is continuously monitored and adjusted using CO and O₂ levels in the flue-gas as guidelines. Access doors and hatches with covers are mounted on all sites where the operation, maintenance or repair of the furnace may be necessary. – The design of the furnace allows for a substantial improvement of the combustion process and provides a competitive advantage to our company and its clients, said Nerijus Rinkevičius, adding it received Gold Medal as Lithuanian Product of the year in 2012. Installed vertically the two boilers are of a flue-tube type with three courses. They are equipped with an automated pneumatic soot cleaning system as well as maintenance hatches and inspection openings allowing for
Bioenergy no 5 September 2015
To see the actual publication please follow the link above