Abstract: In a reaction device in which catalyst layers having vertical passages for a waste gas are arranged, gas rectifying plates are disposed at regular intervals above the catalyst layers and these rectifying plates are each supported by a shaft at the upper portion thereof, moving the lower end portions of the adjacent rectifying plates into contact with each other so as to maintain a V-shape region for a predetermined period of time.Collecting dust in the waste gas in the V-shape region formed by the rectifying plates and then dropping the dust downwardly onto the catalyst layers intermittently, and thereby cleaning the surfaces of the catalyst layers.

Abstract: A method for reactivating catalysts which comprises the steps of:jetting dry steam into a reactor which is charged with the catalysts deteriorated in performance, in order to remove dust adhering to and accumulating on the surfaces of the catalysts;spraying wet steam of 0.4 or less in wetness thereinto to elute and remove water-soluble poisonous materials accumulated inside the catalysts; anddrying the catalysts with the dry steam.

Abstract: A solid-gas contact reactor for dirty exhaust gas is characterized by a first dust-proof plate provided on contact areas between a lower surface of a support base for supporting packages of catalyst layers in each stage and a reactor wall so that the first dust-proof plate makes an angle equal to or larger than the rest angle of dust in the exhaust gas with respect to the support base. Second dust-proof plates are provided on contact areas between adjacent ones of the packages of catalyst layers in each stage and contact areas between the reactor wall and frames of the packages of catalyst layers and the second dust-proof plates make the same angle with respect to the frame structure.

Abstract: A rectangular-solid packaged catalyst assembly made up of a plurality of rectangular-solid unit catalysts stacked and assembled together, the unit catalysts having a honeycomb structure with a multiplicity of gas passages each. Heat-resistant packings are used to cover at least the vertices and the neighboring areas of the faces of the unit catalysts other than the gas-passage faces and also to cover the edges of the gas-passage faces surrounding the gas passages, the packings being integrally secured to the unit catalysts and packaged together in a rectangular-solid housing. Retaining strips are placed over the packings on the edges of the gas-passage faces on at least either the gas inlet or outlet ends of the unit catalysts and are securely attached to the housing.