Investigation of collection efficiency of electrostatic precipitator for small heating appliances

In northern countries, biofuel is widely used to provide centralized heating and electricity production. In Lithuania, use of biofuel is also currently increasing: it is used not only in industrial areas but is also as a popular type of fuel for small scale household furnaces. Although carbon dioxide, released during combustion of biofuel, is not treated as a gas causing the greenhouse effect, the main disadvantage of this type of fuel in comparison to combustion of some gaseous or liquid fuels is rather high emissions of coarse, fine and ultrafine solid particles. Long term exposure to such types of particulate matters causes health problems. Electrostatic precipitation is a very reliable method to control particulate emissions from boilers, incinerators, and other industrial processes. However, its application for small scale heat production appliances is still limited. The aim of this work is to evaluate the capability (efficiency) of a small scale electrostatic precipitator to capture solid particles emitted during incineration of wood pellets. Wood pellets were incinerated in an automatic boiler with the rated thermal output of 50 kW. During investigations, distributions of solid particles were measured in the chimney using infrared particle sizer which is able to measure particles in the range from 0.4 mu m to 300 mu m. Results showed that there are mainly solid particles in the flue gases with diameters from 0.4 mu m to similar to 20 mu m. Investigations were performed at different supply voltages to the discharge electrode of the electrostatic precipitator (ESP). This allowed determining collection of the particles by the ESP in case of different strength of the electrostatic field. In general, the total collection efficiency of similar to 99% was achieved.