Grate plates

Figure 5-24G. Direct mechanical action can be increased by the addition of a grating plate to the draft tube. By permission, Weber, A. R, Chem. Engr., Oct. 1953, p. 183 [23].

A number of different constructions have been developed for tray columns the essential ones are still bubble-cap, valve, sieve and grating plates. Bubble-cap plates are the oldest development and, due to the high production costs, they are rarely used today. 

Water injection equipment must be carefully designed and properly serviced. Too much or poorly atomized water sprayed into the cooler is liable to cause serious trouble because the very fine particles of clinker will react with the water. As a result, for example, the air holes in the grate plates may become choked or the hoppers and discharge devices for the grate riddlings may become blocked solid with hardened masses, while clogging of fabric filters may also occur. 

For attaching the grate plates to the support girder the so-called fingerless construction is used, enabling the plates to be dismantled by withdrawing them downwards. 

Fig. 25 Wearirtg or curb plates on fixed grate plates (from Steinbil, 1972 ...

In the main, the variables which are measured and recorded are temperatures, pressures, flow rates and rotational speeds, comprising more particularly secondary air temperature exhaust air temperature clinker exit temperature temperature of grate plates pressure in kiln hood undergrate pressures reciprocating grate movement cooling air rates. 

The burner is located at the front of the LEPOL grid, and receives 20% of the total flow of coal. In order to withstand the new thermal loads, the bricks situated in the decarbonation zone have been replaced by others, richer in alumina the grate plates are now in 30 % chromium steel. The temperature of the grate is controlled and triggers an alarm in the case of too high a temperature. The height of the layer has risen from 18 to 24 cm and the rate of decarbonation from 24 to 47 %. 

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