Centrifugal separator and method for separating particles from hot gas

A centrifugal separator has a plurality of substantially planar walls, including a first wall, defining a vortex chamber having an interior gas volume and for establishing at least one gas vortex in the gas volume, and the gas volume has a cross section that is distinctly non-circular, (and preferably quadrate). In addition to conventional outlets the separator includes a gas inlet having at least one elongated jet-defining wall with a free end portion extending into the gas volume a first distance from the first wall, to define a gas jet that extends substantially tangentially to the gas vortex in the gas volume. An insert extends between the jet-defining wall free end portion and the first wall and defines a gas flow direction changing surface. The insert may be substantially solid refractory material, or include a number of cooling fluids circulating tubes, and a gas flow direction changing surface may be substantially planar or curved. The first distance is typically at least 50 mm, but less than 25% of the dimension of the wall perpendicular to the first wall. The jet defining wall and the gas direction changing surface may make an angle alpha between 20 DEG -80 DEG and the first distance may be between 0.2-5 times the width of the gas inlet. The height of the gas inlet is at least twice as great as its width.