Abstract: A boiler includes a flow channel having a selected chamber delimited by walls made at least partly of conductive material and being grounded, and a device arranged at least partially inside the selected chamber. The device includes an ion source comprising a corona electrode and an electrically passive body having an opening for corona discharge. The corona electrode is located inside the electrically passive body. A fan/shielding-gas connection is in the electrically passive body. The shielding gas exits the electrically passive body through the opening. The device also includes a high-voltage source for the corona electrode. The walls of the selected chamber of the boiler form a ground potential for the corona electrode to collect the fine particles of flue gases on the walls of the selected chamber.

Abstract: A gas cleaning apparatus includes: an ion source to provide an ion beam, a charging zone to form charged particles by exposing particles of a particle-laden gas to the ion beam, and a filter element to collect the charged particles, wherein the ion source includes a corona electrode to generate ions by a corona discharge, the ion source is arranged to form the corona discharge in a protective gas, and wherein the apparatus is arranged to form the ion beam by using an electric field to draw the generated ions from the corona discharge to the particle-laden gas.

Abstract: A method for collecting fine particles from flue gases onto selected collector surfaces includes leading the flue gases from a combustion chamber to a selected chamber that is part of a flow channel of the flue gasses. The selected channel is delimited by walls presenting the selected collector surfaces. Gas ions are formed with aid of a corona discharge of an ion source inside the selected chamber. The ion source includes a separate body relative to the selected chamber that is electrically passive and contains a corona electrode maintained at a high-voltage relative to the collector surfaces. The selected collector surfaces form a counter potential to the high voltage of the corona electrode. The gas ions are led to the selected chamber and mixed with the flue gases to charge the fine particles in the flue gas which are collected on the selected collector surfaces.

Abstract: A method for separating particles from particle-laden gas. Charged particles are formed by charging particles of a particle-laden gas. A gas jet is provided by guiding the particle-laden gas by a flow guide. Particles from the gas jet are collected to a collecting electrode by an electric field. An effective collecting area of the collecting electrode is positioned such that gas velocity gradient at each point of the effective collecting area is smaller than 10% of the maximum gas velocity in the gas jet divided by the height dimension of the jet.

Abstract: A method for separating particles from particle-laden gas. Charged particles are formed by charging particles of a particle-laden gas. A gas jet is provided by guiding the particle-laden gas by a flow guide. Particles from the gas jet are collected to a collecting electrode by an electric field. An effective collecting area of the collecting electrode is positioned such that gas velocity gradient at each point of the effective collecting area is smaller than 10% of the maximum gas velocity in the gas jet divided by the height dimension of the jet.