Method and apparatus for removing alkali from cement system |
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| 申请号 | US3692287D | 申请日 | 1970-12-10 | 公开(公告)号 | US3692287A | 公开(公告)日 | 1972-09-19 |
| 申请人 | ALLIS CHALMERS MFG CO; | 发明人 | KOHL ROBERT F; HEIAN GLENN A; | ||||
| 摘要 | A method and apparatus is disclosed for reducing the alkali content of cement clinker in which dust and volatilized alkalies are removed from hot clinkering kiln exit gases utilized to preheat particulate raw material. A stream of kiln exit gases at 1,800* F., with entrained dust and volatilized alkalies, are collected by a hood that turns the stream upwardly countercurrent to the falling feed material. A portion of the upwardly moving stream is bypassed upwardly and away from the falling feed material and into a mixing box as close to the hood as is permitted by surrounding structures. Air is admitted to the mixing box and mixed with the bypassed portion of the stream to chill the mixture to below 600* F., to freeze the alkalies. This sudden chilling of the bypassed gas stream freezes the alkalies to particles, most smaller than 10 to 20 microns. The chilled gas stream is then passed through a cyclone separator to collect dust particles larger than 10 to 20 microns and a minor portion of the frozen alkalies. The gas stream is then passed through an electrostatic precipitator or a plurality of gas permeable bags to collect dust particles smaller than 10 to 20 microns and a major portion of the frozen alkalies. The bypassed portion of the gas stream from the hood to the mixing box passes through a conduit that tapers toward the mixing box, and the stream from the mixing box to the cyclone separator passes through a conduit that tapers away from the mixing box, to provide an increase in velocity of the gas to maintain the dust and frozen alkalies suspended in the gas. A ported cage is mounted within the mixing box to create turbulence and efficient mixing of the air and gas. | ||||||
| 权利要求 | 2. In a method according to claim 1, the gases, dust and volatilized alkalies at about 1,800* F. are collected and air is admitted and mixed with the bypassed portion of the stream with the air input being sufficient to lower the temperature of the mixture to below 600* F. 3. An apparatus for preheating particulate material for a rotary kiln with hot exit gases from the kiln containing dust and unwanted volatilized mineral constituents, having a hood with a gas inlet opening in a vertical plane for receiving kiln gases and a gas discharge opening above the gas inlet opening for discharging kiln gases upwardly through material preheating means through which particulate material drops and is preheated, the improvement comprising: a. a bypass conduit means connected to the hood at a location adjacent to and above the gas inlet opening but below the gas discharge opening; b. a mixing box in the bypass conduit means in proximity to the hood; c. an atmospheric air admitting means connected to the mixing box for admitting air at atmospheric temperature to mix with hot gas in the box and precipitate unwanted volatilized mineral constituents in the hot gas; and d. separating means connected to the bypass conduit means downstream of the mixing box for separating dust and precipitated unwanted mineral constituents from the gas. 4. In an apparatus according to claim 3 the separating means comprising a centrifugal separator. 5. In an apparatus according to claim 3 the separating means comprising a cyclone separator for removing from the gas stream dust particles 10 to 20 microns and larger and a minor proportion of the precipitated unwanted mineral constituents, and a fine particle separator downstream of the centrifugal separator for removing from the gas stream particles smaller than 10 to 20 microns and a major proportion of the precipitated unwanted mineral constituents. 6. In an apparatus according to claim 5, the fine particle separator being an electrostatic particle precipitator. 7. In an apparatus according to claim 5, the fine particle separator comprising a plurality of gas permeable filtering bags. 8. In an apparatus according to claim 3, at least a portion of the bypass conduit means between the hood and the mixing box being tapered toward the mixing box and at least a portion of the bypass conduit means between the mixing box and the separating means being tapered away from the mixing box, to provide an increase in velocity of gas passing therethrough to maintain the dust and precipitated unwanted mineral constituents suspended in the gas. 9. In an apparatus according to claim 3, a ported cage of heat resistant material mounted within the mixing box for creating turbulence of the air and gas and promote mixing thereof. |
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