| 摘要 |
<p>A blast-cleaning system includes an air compressor, a pressure vessel which pressurizes a blasting material and mixes it with compressed air, and a blasting unit connected to an outlet of the pressure vessel for blasting the interior surface of a structure to be cleaned. A conduit arrangement in the blasting apparatus is divided into two branches downstream from a main air valve. One branch opens into an upper portion of the pressure vessel to pressurize the blasting material; the other branch is connected to a mixing valve for mixing the blasting material with compressed air. Valves arranged in the conduit branches are individually set and maintain a constant pressure difference between the compressed air used for pressurization and the compressed air used for mixing, independent of the level of the operating pressure of the main compressed air from the main air valve. The pressure for pressurizing the blasting material is set higher than the mixing pressure. The blasting unit is provided with rotating, preferably belt-driven blast arms with nozzle outlets through which the surface is blasted at an angle. The blasting unit may be supported within the structure to be cleaned either with adjustable wheels or by a brush arrangement. A vacuum and filtering device may also be connected to the duct so that the pressure vessel, blasting unit, duct and filtering device form a substantially closed system.</p> |
