01 Existing problems

A company carried out technical transformation on two original 2000t/d clinker production lines in 2009, and planned to complete the technical transformation project and put it into production in June 2011. After technical reform, the production capacity of original clinker production line reached 2500t/d, and the highest reached 3100t/d. During technical renovation, the design and selection of grate cooler was XSJ 929S /1141H, the nominal area of grate bed was 77.4m², the actual area was 68.2m², and the production capacity was 2800t/d. It was divided into two sections. The mechanical transmission structure was used. Moreover, because the span of supporting roller group of the movable frame under the grate of the grate cooler is too large, the movable frame of the second stage of the grate cooler frequently breaks. In order to completely solve the phenomenon of large force and easy fracture of the movable frame, the problem can be solved by adding a group of supporting rollers after repeated research and calculation. The hidden trouble of the equipment has been thoroughly solved through the on-site implementation.

Measures and effects before and after technical reform

The structure under the second grate of the original grate cooler before technical modification is shown in Figure 1.

Fig. 1 Structure diagram under the grate of the second stage of grate cooler

As shown in Fig. 1, the layout of the roller group under the grate is as follows. At the position of the second-stage transmission device, the maximum span of the roller group under the grate reaches 6660mm, with large span and long-term overload operation, leading to the frequent fracture of the second-stage movable frame around point A in the figure. When the movable frame cracked, the whole frame subsided at the cracking place, and the problem could not be found in time during the inspection. The grate cooler operated for a long time with disease, which led to the gradual increase of resistance of the transmission device of the second stage of the grate cooler. In serious cases, the second stage of the driven shaft tightening channel steel would be fractured, the grate bed would be crushed and the rotary kiln would be stopped. This is usually done by replacing the active frame in whole or in part.

Combined with the actual production situation and equipment structure form of the company, in order to better serve production, reduce equipment stopover, improve equipment operation rate and reduce production cost, the company decided to partially replace and repair the movable frame of the second section of grate cooler during the overhaul in January 2016, and carry out technical transformation on the movable frame of 6660mm. The structure under the grate of the second stage of the transformed grate cooler is shown in Figure 2.

Fig. 2 Schematic diagram of the structure under the grate at the second stage of the transformed grate cooler

As shown in Fig. 2, after the transformation, the span of 6660mm under the movable frame of the second stage of the grate cooler is large. In order to avoid the driven shaft of the second stage, enough maintenance space is left and A group of lower grate roller groups is added at the position of point A, which can increase the supporting points of the movable frame, thus reducing the span and improving the stress condition of the movable frame. It also reduces the amount of deformation in the production of the movable frame.

After the transformation, after more than one year of production inspection, it has been proved that the transformation has completely solved the fracture accident of the movable frame at the 6660mm span of the second stage of grate cooler due to the large span and unbalanced stress. It effectively solves the occurrence of such equipment accidents in the production process, improves the equipment operation rate and saves the production cost.

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