PLAMELESS COMBUSTION — ELLIS. 649 



water heater, constructed on the same principle as the boiler. Dur- 

 ing a test carried out in Leeds, in which steam was generated at 

 100 pounds above atmospheric pressure, the temperature of the 

 products leaving the boiler-tubes was 230° C. — the actual boiling 

 point of the water being 170° C. These products, still containing a 

 certain amount of valuable heat, were passed through a feed-water 

 heater, only 1 foot long, containing nine tubes, of the same diameter 

 as those in the boiler, packed with granular material. The hot prod- 

 ucts, continually baffled in their passage through the tubes, readily 

 imparted their heat to the cold feed-water surrounding them; and 

 their temperature was thereby reduced to somewhat less than 100° C. 



THE TEN-TUBE EXPERIMENTAL BOILER. 



The connections to the front of this boiler consisted essentially of a 

 tube for the supply of gas, and another for the supply of air. The 

 gas and the air were mixed before entering the feeding chamber 

 attached to the front plate of the boiler; the gaseous mixture was 

 burned in the tubes of the boiler; and the products passed outward at 

 the other end into a small chamber, and thence into the feed-water 

 heater. 



The mixture of gas and air was passed into the feed chamber of 

 this boiler at a pressure of 17.3 inches water gauge. This pressure 

 was necessary in order to overcome the resistance of the packing of 

 the tubes. The pressure of the products entering the tubes of the 

 feed- water heater was 2 inches water gauge, so that the pressure nec- 

 essary to force the gas through the zone of combustion, and there- 

 after through the remainder of the boiler tubes, was about 15 inches, 

 water gauge. In carrying out the test the water was evaporated at 

 100 pounds above atmospheric pressure; the temperature of the 

 boiling water was therefore 168° C, or 337° F. The temperature 

 of the combustion products leaving the boiler tubes was 230° C. The 

 average temperature of the products leaving the feed-water heater 

 was 95° C, or 203° F. The temperature of the water entering the 

 feed-water heater was 5.5° C, or 42° F., and it was heated to 58° C, 

 or 136.4° F., before entering the boiler, entirely at the expense of the 

 burnt gases. 



The ratio between the heat transmitted to the water and the net 

 heat of combustion of the burnt gas in the boiler was 0.94: i. e., over 

 90 per cent of the heat generated was utilized. 



It is one of the prominent merits of the new sj^stem that the gas 

 is burned completely with a minimum excess of free oxygen. Dur- 

 ing the test in question, the average proportion of carbon dioxide 

 in the combustion products was as much as 10.6 per cent, while the 

 oxygen was as low as 1.6 per cent. The most careful examination 

 of the products failed to reveal the presence of the slightest trace of 



