Flue gases from pellet combustion are measured in a unique study
At Helsingin Energia’s Hanasaari power plant, particulate and gas emissions are measured with a method that has not previously been used anywhere else in the world. In the flue gas measurements, it is possible to watch the combustion products produced in the mixed combustion of biofuel and coal all the way from the power plant furnace to the atmosphere.
The flue gas samples are taken from three places in the combustion process: the furnace, the chimney and the flue gas trail. In both furnace measurements and chimney measurements, we are able to test new measurement methods and equipment: the entire process of measuring particulate and gas components in the flue gas trail with equipment installed in a helicopter is the first of its kind. The main focus of the study is on the measurement of the number and size distribution of fine particles, carried out with real-time measuring equipment.
The results obtained from measurements carried out in the chimney are compared with the samples collected from the furnace and the flue gas trail. Along the way, it will be established, e.g. whether the particle sizes and concentrations change, how the emissions spread, and whether their chemical composition changes as the flue gas mixes with the atmosphere. And all this information can be combined with the knowledge of how mixed combustion of biofuel and coal affects the actual combustion process and emissions.
- This is unique from the researcher’s point of view: you only get to do something like this once in about ten years, says Docent Topi Rönkkö of Tampere University of Technology.
New pellet grades are tested
Helsingin Energia is also testing new pellet grades at the Hanasaari power plant. It has already been established in previous tests that, with the current equipment, residential-grade pellets can replace coal with respect to 5–7 per cent of the boiler’s fuel input. Now, corresponding tests are carried out with industrial-grade pellets. Torrefied and steam-exploded pellets are also tested. The concurrent test programme using several pellet grades is unique in the industrial scale.
- We are particularly interested in information obtained from the boiler furnace of the power plant. With this information, we are able to assess the corrosion impacts of biofuels in the boiler, explains Process Engineer Jani Rautiainen of Helsingin Energia.
The study is part of CLEEN Oy’s MMEA research program. The participants to the research program are Helsingin Energia, the Finnish Meteorological Institute, Tampere University of Technology, Metso Automation Oy, Valmet Oyj, HSY, Helsinki Metropolia University of Applied Sciences, VTT, and Dekati Oy.