s 
BULLETIN 85, U. S. DEPARTMENT OF AGRICULTURE. 
allowed the uncondensed steam to escape to the atmosphere. The ex- 
haust box was built up of cypress lumber, being about 12 inches square 
by 14 feet long. The heat contained in the exhaust steam from the 
five steam turbine driven separators and five reciprocating pumps was 
sufficient for pasteurizing 17 per cent cream at the rate of 18,360 
pounds, or 9.18 tons, per hour. This was actually done during the 
first hour of test. The initial temperature of the cream was 49.5° F., 
and it was raised to a pasteurizing temperature of 147° F., or through 
a range of 97.5° F. 
As 1 boiler horsepower is equivalent to the evaporating cf 34 \ 
pounds of water from and at 212° F., the boiler horsepower per hour 
required for pasteurizing under the above conditions was 67.1. It is 
therefore obvious that had this exhaust steam been allowed to go to 
waste and five steam been taken direct from the boiler for pasteuriz- 
ing, the boiler capacity of the plant would have had to be increased 
by this amount, viz., 67.1 horsepower. In other words, there was a 
saving in boiler capacity, by using the heat in the exhaust steam for 
pasteurizing, of 67.1 horsepower. As has been previously explained, 
it was necessary to employ some such arrangement as that illustrated 
in the diagram in order to avoid putting a back pressure on the turbine 
separators, although this arrangement entailed a loss of heat due to 
the double heat transfer from the exhaust steam to the water and from 
„ the water to the cream. 
Assuming that the boiler and furnace efficiency was 50 per cent 
and that the coal used had a heating value of 12,500 B. t. u. per 
pound, then the fuel saved per hour with this arrangement is 
67 1 X 34 5 X 970 4 
— 19 500 X 50 = ^® pounds. If the pasteurizing equipment is 
run 4 hours a day for 310 days in the year, the annual saving in 
359 X 4 X 310 
fuel is tt^t^ = 198.7 tons, which at S4 per ton would amount 
2,240 r 
to $794.80. In addition to the fuel saved, there is a further saving 
due to the decreased boiler capacity of the plant. 
It is evident that if the exhaust steam from the separators and 
pumps had been allowed to escape it would have been necessary 
to have taken live steam from the boilers for the purpose of pasteur- 
izing, and this would have taken an additional 70-horsepower boiler, 
which would have cost approximately $14.75 per boiler horsepower 
installed, or $1,032.50. Figuring the interest on the money invested 
at 6 per cent per annum and depreciation and repairs at 10 per cent, 
there is a saving in addition to the fuel of $165.45, making a total 
saving of $794.80 + $165.45 = 8960.25, to say nothing of the increased 
labor of firing the boiler. Adding this to the actual cost would 
bring the cost of pasteurizing 100 pounds of cream in this particular 
plant up to $0.0512, or an increase of 12.3 per cent. The fuel cost, 
