Importance

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Abstract

A silencer, for silencing and purification of exhaust gases, comprises an air-tight casing (1) connected to an exhaust inlet pipe (2) and to an exhaust outlet pipe (3) and contains at least two acoustic compartments (4i, 4ii) and one or more monolithic bodies (5) such as catalysers or particle filters through which exhaust gases flow in a flow direction in longitudinal channels or porosities, and one or more pipes or channels (6, 7), at least one pipe or channel penetrating one or more of the monolithic bodies (5) and guiding exhaust gases in a flow direction which is opposite to the flow direction in the channels or porosities of the monolithic body (5), and at least one of the pipes or channels (6, 7) connecting the at least two acoustic compartments (4i, 4ii). The general flow direction is preferably reversed substantially immediately upstream of a penetrated monolithic body (5) and substantially immediately downstream of either the same monolithic body (5) or of another penetrated monolithic body. Solid particles active for catalytic reduction of NOx, or a spray of a liquid containing an aqueous solution of urea and/or ammonia, active for catalytic reduction of NOx, may be injected into the exhaust gases to impinge on a catalytic layer (35, 36) applied on a baffle (13), an end cap (11, 12) or a flow element being arranged so that said particles and/or droplets impinge thereon.

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First Claim