Producer gas or water gas generators, with or without

84.05 - Producer gas or water gas generators, with or without their purifiers; acetylene gas generators and similar water process gas generators, with or without their purifiers. 8405.10 - Producer gas or water gas generators, with or without their purifiers; 8405.90 - Parts acetylene gas generators and similar water process gas generators, with or without their purifiers This heading covers self-contpined a paratus and plant for generating -any kind of gas (e.g., producer gas, water gas and rmxtures t ereof, or acetylene) whatever the intended use of the gas produced (lighting, industrial heating, feeding gas engines, welding or cutting metals, chemical synthesis, etc.). % The heading also includes producer gas generators specially constructed for use in motor vehicles, but excludes acetylene generators which are in fact lamps requiring only the fitting of a burner (heading 94.05). (A) PRODUCER GAS GENERATORS These usually consist of a closed cylinder, general1 fitted with a refractory lining or a watershaking or revolving t e), wth provision cooled double wall enclosin a grate (either of of air and steam) by suction or blowing. A ick bed of fuel is for passing a current of air burned on the grate and the of air and steam is regulated so that combustion is incomplete. The decomposition of the water and the incomplete combustion of the fuel yield carbon monoxide and hydrogen. The resultant mixture of carbon monoxide, hydrogen and nitrogen (producer gas) is drawn off at the top of the apparatus. fix2 In certain enerators of the " reversed combustion " type, the air is blown from the top to the bottom an alon the sides of the cylinder and the gas is collected at the bottom of the apparatus, below k e grate. This allows for more complete combustion of tars, etc. (B) WATER GAS GENERATORS These are of similar construction, but are arranged so that air and a spray of water or steam are blown in alternate phases into the a paratus. The gas resulting from the water hase is a mixture gas having a higher heatipg power &an poducer gas. of hydrogen and carbon monoxide It may be collected separately from the pro ucer gas obtained d w g the air phase or the two gases may be mixed. d Both producer gas and water gas enerators may be adapted for burning many kinds of solid fuel(e.g., coal, coke, charcoal, woo$ vegetable or other waste). For certain uses, articularly for su lying gas engines, producer or water gases must be cleaned of im urities suc as dust, tars, su p urous compounds, etc,, and sometimes reheated or cooled. For &is urpose, the generators are often fitted with purifiers (comprising perforated cones, coke bedl= s, scrubbers, etc.), coolers, dryers, reheaters, etc. Such pmfiers and other auxiliary apparatus are classified with the generators when presented therewith, provided they are clearly sultable for use together. When presented separately they fall in their own respectwe headings (e.g., purifiers in heading 84.21). f PR (C) ACETYLENE WATER PROCESS GAS GENERATORS These are generally of simple construction, consisting of a water-sealed as reservoir, the movement of which, as it is charged and discharged, automatically controls e gas generating device. There are three types of generating devices : f (1) Producing intermittent immersion of the mass of calcium carbide in the water. (2) Providing for the gradual. addition of carbide to water. (3) Causing water to be dripped on to the carbide. (D) OTHER WATER PROCESS GAS GENERATORS These include oxygen generators (e.g., those used in submarines) and ethylene generators (e.g., those based on the action of water on certain chemicals). PARTS Sub'ect to the general provisions regarding the classification of parts (see the General Exp anatory Note to Section XVI), parts of the apparatus of this heading are also classified here (e.g., gas generator bodies, grates, gas collectors and water-carbide mixers). * * * The heading also excludes : (a) Free-piston generators for gas turbines (heading 84.14). (b) Coke ovens (e.g., town gas generators) (heading 84.17). (c) Ozone generating and diffusing apparatus, electric, designed for non-therapeutic purposes (e-g., for industrial uses, for the omnisahon of premises), and electrolytic gas generators for the generation of, e.g., nitro en dioxide, hydrogen sulphide or prussic acid (heading 85.43) and ozonotherapy apparatus beading 90.19).