Abstract: In an exhaust gas purification apparatus or other apparatuses that are supplied with ammonia generated from a urea aqueous solution and causes selective reduction and purification of nitride oxides, a shot peening treatment is applied to a welded portion of its exhaust pipe which is made of a ferritic stainless steel plate and through which exhaust gas containing ammonia and hydrogen passes. By shot peening the welded portion of the exhaust pipe, a tensile residual stress in the welded portion of the exhaust pipe can be replaced with a compressive residual stress, and further the diameter of metal crystal grains in the welded portion can be reduced. In this way, the durability of the exhaust pipe can be improved.

Abstract: In an exhaust gas purification apparatus or other apparatuses that are supplied with ammonia generated from a urea aqueous solution and causes selective reduction and purification of nitride oxides, a shot peening treatment is applied to a welded portion of its exhaust pipe which is made of a ferritic stainless steel plate and through which exhaust gas containing ammonia and hydrogen passes. By shot peening the welded portion of the exhaust pipe, a tensile residual stress in the welded portion of the exhaust pipe can be replaced with a compressive residual stress, and further the diameter of metal crystal grains in the welded portion can be reduced. In this way, the durability of the exhaust pipe can be improved.

Abstract: An engine exhaust gas purification apparatus for engine includes a mixing device for promoting mixing of a liquid reducing agent or a precursor thereof and exhaust gas is disposed at a position at which, when an engine is operating in a predetermined operating state, the liquid reducing agent or the precursor thereof injection-supplied from an injection nozzle impinges on substantially an entire surface of the mixing device. The predetermined operating state may be, for example, an operating state in which a solute tends to deposit from the liquid reducing agent or the precursor thereof. Thus, the liquid reducing agent or the precursor thereof adhering to the mixing device or an exhaust passage is reduced in absolute amount, thereby preventing that only a solvent evaporates from the liquid reducing agent or the precursor thereof adhering to the mixing device or the exhaust passage to deposit the solute.

Abstract: An engine exhaust gas purification apparatus for engine includes a mixing device for promoting mixing of a liquid reducing agent or a precursor thereof and exhaust gas is disposed at a position at which, when an engine is operating in a predetermined operating state, the liquid reducing agent or the precursor thereof injection-supplied from an injection nozzle impinges on substantially an entire surface of the mixing device. The predetermined operating state may be, for example, an operating state in which a solute tends to deposit from the liquid reducing agent or the precursor thereof. Thus, the liquid reducing agent or the precursor thereof adhering to the mixing device or an exhaust passage is reduced in absolute amount, thereby preventing that only a solvent evaporates from the liquid reducing agent or the precursor thereof adhering to the mixing device or the exhaust passage to deposit the solute.