STEAMING TESTS. 35 
FEATURES OF THE INVESTIGATION. 
It is probable that the general efficiencies obtained are fairly good. But the Survey 
clearly realizes that it is working with limits imposed by its particular apparatus, though 
these limits are not the fault of the Heine construction, inasmuch as any combination of 
grate, furnace, and boiler would have faults. For this reason and others all steaming tests 
are only approximately comparative and not final as between coals. Steaming tests should 
be made more with the idea of eliminating them in future years than of accepting them as 
final. Toward this end engineers should work with the aid of chemistry and physics. 
The determination of the calorific capacity of the various steaming coals has shown, during 
the last few years, that these coals contain a larger number of heat units than were formerly 
credited to them. This has resulted in somewhat lower efficiencies than have sometimes 
been reported. 
Before closing the present series of trials it is hoped that tests may be made with several 
standard coals, which will show the effect of changes in certain fundamental ratios on the 
over-all efficiency of these outfits. 
Some of the more important results of the steaming tests are given on pages 53-233, in the 
detailed report on the various coal samples used. 
SPECIAL TESTS. 
Attention is called to some special tests made during the period covered by this report, as 
follows: 
TESTS ON MIXED COALS. 
Tests Nos. 240, 248, and 254 were made on Virginia No. 4. In the first test the clinker 
fused onto the grate so as to be very difficult to remove ; in the two remaining tests about 
200 pounds of nut-sized limestone was spread over the grate before starting, so that the 
clinker lifted up very easily. The average boiler efficiency for these three tests was 66.6 
per cent. 
Test No. 242 was run on Pennsylvania No. 8 dried. The boiler efficiency was 68.3 per 
cent. Cleaning was very easy. The Virginia coal was very free burning and long flaming, 
and the Pennsylvania coal very short flaming. It was thought that by mixing them, as a 
matter of experiment, a better result would be attained; but the boiler efficiency was only 
61.7 per cent. There were outside reasons for the result being low, but the best that can be 
said is that the experiment was indeterminate. The grate behavior was improved. 
TESTS ON DRIED COALS. 
Some of Pennsylvania No. 8 was dried and burned in test No. 242. The moisture to start 
with was only about 3 per cent and it was reduced to 0.42 per cent by drying in a Bartlett 
rotary drier at 240° F. At the same time some of the volatile matter was driven off, so that 
the British thermal units of the dry coal fell from about 14,800 to 14,660; with the average 
boiler efficiency of the four tests run on the coal as received, the performance was a shade 
better only, and on the whole there was a considerable loss. 
Two tests, Nos. 243 and 244, were run on Ohio No. 9 B, dried after washing, with a slight 
loss of efficiency, not to speak of the drying having reduced the British thermal units of the 
dry coal about 1.5 per cent, as in the other case. 
These drying tests were made as preliminary to some tests to be run on dried lignites. 
TWENTY-FOUR HOUR RUNS. 
It can be calculated that from 1 to 2 per cent of the heat generated in a test is lost in heat- 
ing the brickwork in the morning, notwithstanding that the furnace is fired hard foi two 
hours before starting. To learn something of this, some tests were run on the same coals, 
starting the very instant the preceding ones ended. The preceding test numbers were 237, 
243, and 249; average boiler efficiency, 66.2 per cent; average furnace temperature, 
2,388° F. The immediately succeeding test numbers were 238, 244, and 250; average 
boiler efficiency, 67.3 per cent; average furnace temperature, 2,355° F. These tests show 
an average gain of 1.1 per cent, which is nonconclusive. The research is being continued. 
