Top dead centre

Top-feed drum filters are used for the treatment of very fast settling solids that cannot easily be kept in suspension. A drum filter may be preferable, rather than a horizontal pan or similar filter, because of its low cost, simplicity and reliability, and because of the relative ease with which it can be fitted with appropriate accessory features. A top feed drum filter incorporates multi-compartments, drainlines and a rotary valve identical to those in a conventional drum filter. The feed slurry is introduced at, or just before, top dead centre, and the cake is discharged from 90° to 180° from the feed point. The feed slurry can be distributed across the drum by sprays or a weir box, or it may be contained within a 3-sided head-box which is sealed against the moving drum at each end and across the back on the ascending filter surface. For materials which do not cake together sufficiently to be self-supporting on the drum surface, a hopper-type top feed filter may... 

To say that another way, at 3000 rpm, the piston in the cylinder moves from Top Dead Centre to Bottom Dead Centre in lOmS. 

It gets worse. The ignition spark does not occur at Top Dead Centre. If we assume that the spark is at 30 degrees after TDC, then only 5/6 of our lOmS is available for any useful burn. This means that we are looking at a burn period of some 8mS. 

Retard the timing to about 30 degrees after Top Dead Centre. 

The duration of the compression stroke in the calculated times (Table 6.14) corresponded to approximately 50 ms, signifying that autoignition occurred after top dead centre, as observed experimentally. The choice of bdc as the initial condition is essential to permit the development of spontaneous combustion during the course of the compression stroke as the gas pressure and temperature increase. This definition of the time for ignition differs from that given by, (i) the admission of reactants to a hot, closed reaction vessel, (ii) the end of compression in an RCM, or (iii) the passage of a shock through the reactants in a shock tube. 

Washing on a drum filter starts at the horizontal centreline on the rising side and extends up to 15° past top dead centre. 

Figure 6. Unfiltered raw data signals for the total tangential (friction + mass) force and the mass force at 20 Hz oscillation, synchronised by the position sensor signals (only one shown), between two top dead centre positions of the crankshaft.

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