【Technical】 φ4.2mx13m cement mill bag filter technology transformation

Jiangxi Wannianqing Cement Co., Ltd. Wannian Cement Factory (hereinafter referred to as our factory) In 2010, a new dry-cement production line of Nissan 5000t clinker was newly built. The cement grinding system adopts extrusion joint grinding system (open grinding system) Configured as HFCG160-140 roller press + Φ4.2m × 13m ball mill HFV4000V classifier + JPF128-2x12 big bag dust collector, grinding machine output is 160 ~ 180t / h or so. Due to lower output during open jet mill and higher requirements for central control operation, in order to increase mill output and reduce costs and improve profitability, the open mill grinding system was reformed to the present closed circuit grinding mill system in 2014. The main content of the renovation is to add a FWT4500.0 double separation type high efficiency separator and replace JPF128-2x12 big bag dust collector exhaust fan and motor.

After the transformation mill output increased to 220t / h or so, reaching the transformation goal. However, during the subsequent operation, it was found that the pressure difference between the large bag filter and the dust collector increased greatly from about 1500 Pa to 3000 ~ 4000 Pa. Due to the pressure is too high, the filter bag is difficult to withstand long-term, frequent damage, excessive emissions of dust, polluting the environment, increasing environmental pressure. At the same time frequent replacement of filter bags, increased maintenance workload, Chong high operating costs, reduce the mill operating rate, affecting production tasks completed on time. After in-depth analysis of our factory, we found out the reasons for this phenomenon and solved the problem successfully by retrofitting the dust remover supernormally. Renovation dust collector pressure drop back to 800-900Pa or so, frequent damage to the filter bag to eliminate the natural, production returned to normal. Here to introduce my plant ideas and practices.

1 reason analysis

In 2014, when the open grinding system of our factory was transformed into a closed-circuit grinding system, the output of cement mill will be increased from 160 to 180t / h to 220t / h. The amount of fine powder collected per hour of the precipitator increases by 40-60t , Work load increases, so replace the dust collector fan and motor specifications shown in Table 1. As a result of the closed-circuit transformation increased the separator, into the dust collector dust particle size has changed, the particle size generally lower, Table 2.

As can be seen from Table 2, the fineness of the 80um screen has been reduced from 4.1% to 0.7% and the fineness of the 45μm screen has dropped from 17.7% to 3.9%. The fineness of the dust entering the dust collector has dropped sharply and the grain size is even. Before the transformation of fan operation, a person can put the top of the dust box on the door to open the upper door, after the transformation due to negative pressure to increase two people at the same time forced to open.

Based on the above factors, after careful examination to confirm the pulse valve, poppet valve, gas tank, gas bag pressure gauge instructions, the dust collector out of the duct thermometer pressure gauge parameters show no problem, come to the following conclusion: due to Taiwan increased production , Into the dust collector dust concentration increases, so that the adsorption on the filter bag on the dust layer thickness also increased, increasing the airflow through the bag resistance, dust collector resistance increases, the pressure increase to 3000 ~ 4000Pa.

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