THE WALLARAH COLLIERY. 



255 



tubes ; in this way a continuous circulation is caused. As 

 the passages are large and free, this circulation is rapid, tend- 

 ing to make an equal temperature through the boiler, and 

 being in one direction there are no interfering currents. The 

 large water surface for the disengagement of the steam from 

 the water prevents foaming. The water space is so divided 

 into sections that should any section give out, a general ex- 

 plosion could not take place, but the destructive effects would 

 be confined to the simple escape of the contents. With 

 large and free passages between the different sections, the 

 water line and pressure in all are equalised. 



Fig. 163. The "Sentinel" Patent Multiple Feed-water Filter 

 and Oil Separator. 



The exhaust steam is used to heat the feed water in one 

 of Babcock and Wilcox feed water heaters. (Fig. 162.) The 

 cold feed water enters a chamber at the top of the apparatus, 

 and passes down a nest of tubes to a lower chamber, where 

 the outlet pipe is raised above the bottom so as to be above 

 any sediment. The exhaust steam enters the shell round the 

 nest of tubes at the bottom, and escapes near the top. 



A "Sentinel" multiple feed-water filter and oil separator 

 is used. This apparatus, manufactured by Alley and Maclel- 

 lan Ltd., of Glasgow, is effective and compact, has a large 



