1914] 



on Surface Combustion 



59 



Net cal. value of gas, B. Th'. Us. per cub. ft. at N.T.P. 510 • 5* 



Total net heat supplied, B. Th. Us 52,003,996 



Temperature of products leaving boiler, Fahr. 



Degrees 386°(196°C.) 



Temperature of products leaving feed-water heater, 



Fahr. Degrees... 202° (94-6° C.) 



Total water evaporated, lbs. from and at 212° Fahr.] 49,824 

 Evaporation in lbs. per sq. ft. of heating surface per 



hour 14-1 



Per cent. Dryness of steam 99*3 



Total heat utilized, B. Th. Us 48,208,399 



Ratio ^ Heat utilized ^ ^.^^y^ 

 Net heat supplied 



Power taken by fan 

 [Suction = 20 in. W.G.] 



6097 watts = (say) 8-2 H.P. 



The heat balance of the test is as follows, and for purposes of 

 comparison I will give the heat balance for a trial of a marine boiler 

 fired with a good steam coal of net calorific value 13,800 B.Th.Us. 

 per lb. (volatile matter = 16*1 per cent). 



Gas-Fired 



Surface Com bus 



tion Boiler 



Heat utilized ... , 



iin burnt 

 in unburnt gases 

 by radiation, etc. 



Eate of Evaporation in lbs. per sq. ft. heating 

 surface per hour 



4-3 



The engineer who superintended these trials was very anxious to 

 find out whether, in view of the intensity of the combustion and the 



* An analysis of a typical sample of the gas gave : — 



CO. = 2-5; CO = 6-5; C„H2„ = 3-2; CH, = 28-0; 

 : H. = 48-0 ; Nj, etc. =11-3 per cent. 



j t It should be stated that the boiler was not lagged during the trial, other- 

 wise this figure would have been about 0-94. 



I Deducting the steam equivalent of the power consumed in driving the 

 fan on the Skinningrove boiler, the " over-all efficiency " of the plant \& practi- 

 cally 90 per cent. To complete the comparison, the coal-fired boiler should be 

 similarly debited with the power (whether human or mechanical) expended 

 in stoking. 



