EXPERIMENTAL INVESTGATION ON CIRCULATING FLUIDIZED BED APPLIED FOR PREHEATING AND PRECALCINING RAW MATERIALS OF CEMENT

摘要

For the research and development of circulating fluidized bed furnace (CFBF) to preheat and precalcine raw materials of cement,the running parameters and operating performance of a CFBF system were investgated in a pilot plant test model with 0.3m I.D. and 10m in height. The first CFBF experimental facility for preheating and precaclcining the raw materials in China is introduced and part of the test results are presented. An advanced distributor for powder materials at high temperature was developed and applied to control the recycle ratio of raw materials. the distribution effect was satisfactory. This resolved the problem which occures when powder materials need recycle at high temperature. The decarbonation ratio of CaCO_3 in the raw materials and, temperatures of CFBF system, recycle ratio of the raw materials and the relationships among them were investgated in a pilot plant model.The test result show that the average temperature of CFBF was 850℃ and the recycle ratio was 150%, the decarbonat ion ratio of the raw materials reached 80% or more. For the raw materials of, cement is directly fed into the CFBF, it is preheated and precalcined in the CFBF simutaneously.Thus the huge system of cyclone preheaters can be simplfied or omited resulting in reducing about 30% of the investment'of the system.The heat of waste gas from the CFBF system can be efficiently used for power generation. A rotary kiln of Φ 3. 5/3. 0 × 52m for producing cement clinker has been converted by using CFBF system and power generation technology and put into operation.