Influence of moisture content of wood chips on flue gas losses and thermal efficiency of the boiler

Drvna sečka se sve češće koristi kao čvrsto gorivo u modernim kotlovima na biomasu. U radu je razmatran uticaj vlage u drvnoj sečki u odnosu na gubitke sa dimnim gasovima i efikasnost kotlova. Nominalna korisna toplotna snaga ispitivanih kotlova bila je u opsegu 450 – 2000 kW. Sadržaj vlage u drvnoj sečki je bio 19,21 – 38,23%, donja toplotna moć 10177 – 14139 kJ/kg, dok je sadržaj pepela bio 0,84 – 3,59%. Drvna sečka sa većim udelom vlage ima nižu vrednost donje toplotne moći. Efi-kasnost kotlova se kretala 88,78 – 94,06%, gubici sa dimnim gasovima 5,84 – 11,13% a temperature dimnih gasova 121,83 – 188,44 °C. Formirani su matematički izrazi koji daju zavisnost efikasnosti kotla i gubitke sa dimnim gasovima od udela vlage u drvnoj sečki i temperature dimnih gasova.Wood chips is often used as solid fuel in modern biomass boilers. The influence of wood chips moisture content is analyzed and related to the flue gas losses and the thermal efficiency of the boiler. Nominal useful heat output of tested boilers was 450 – 2000 kW. Moisture content of wood chips was 19,21 – 38,23% with net calorific value 10177 – 14139 kJ/kg and ash content 0,84 – 3,59%. Wood chips with higher moisture content have lower net calorific value. Thermal efficiency of the boilers was 88,78 – 94,06%, flue gas losses 5,84 – 11,13% and flue gas temperature 121,83 – 188,44 °C. Mathematical equations which gives dependences of thermal efficiency and flue gas losses from mois-ture content od wood chips and flue gas temperature are given in paper