Once-through lubrication

Commercial operations are typically once-through at coil-outlet temperatures of 1050-1100°F. and pressures of 350 to 450 p.s.i.g., using 2 to 3 lb. of catalyst per barrel of feed. When processing heavy stocks, naphtha may be included in the feed to ensure complete vaporization, said to be essential for best results. The catalyst employed at Sarnia consists of natural and activated clay that has been previously used for contact treatment of lubricating oils. The catalyst is filtered from the liquid fuel oil, or tar, produced in the process and is normally discarded. Use of the catalyst permits continuous operations to be carried out at much more severe cracking conditions than could be otherwise employed. Erosion is... 

A detailed description of the flow reactor system nsed in these studies has been given earlier [16]. These earlier studies [16] on the thermal and oxidative stability of fresh jet fuel used a procedure whereby fuel was pumped once through the reactor during the experiment. In the present work, 100 mL of vegetable oil was used and recirculated through the reactor for the duration of the experiment. The reactor was allowed to run for 5 h, and then the metal strip was ranoved and analyzed. This represents a regime where the lubricant is repetitively stressed during the experiment. 

Fresh-oil-lubricated (once through ) rotary vane vacuum pumps are generally vacuum pumps of the multicell type. As to their design they differ only insignificantly from the rotary vane pumps detailed above, since operating principle and compression process are very similar (Figures 5.9 and 5.10). 

As in these vacuum pumps the oil passes only once through the pump, the purity of the separated oil is of far less significance compared to rotary vane pumps with circulatory lubrication. Even so, also in the case of fresh-oil-lubricated pumps, the aspect of vapour tolerance must be taken into account because here too the oil may suffer from dilution or the oil film in the pump chamber may be even washed away with the result of very rapid and considerable wear within the pump chamber giving rise to high repair costs. 

Only one once-through process (Fig. 21-ld), the Suspensoid process, has been applied commercially. The catalyst (spent lubricating-oil clay) passes through the cracking furnace along with the oil and is removed from the fuel oil by an Oliver precoat filter. ... 

The author tried the experiment about twenty times and succeeded only once, but more simple methods were xised by our ancestors and have been handed down by some shrine today. The difficulties may come from the following (1) The friction surface is too wide to collect the heat of the friction in one spot. (2) The heat which is necessary to carbonize the wood powder is taken away from the generated heat by the friction. (3) The heat of the friction diffuses by conduction through the mortar and pestle. ( ) The resinoid and tar which come from the carbonization of the wood powder serve as a lubricant, and the heat of friction diminishes. (5) The ignition point of the carbonized wood powder is thought to be 300 00 C from other experiments. This is considerably high. 

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