HISTORY OF THE USE OF 

 SUPERHEATED STEAM 



i 



WHILE it is only within recent years that there has been any com- 

 prehensive data available on the properties of superheated steam, its 

 use is old. Pioneers in the field of modern engineering unquestionably 

 realized that cylinder condensation was the principal cause of low engine efficiency 

 and many devices were tried with a view to its reduction. As early as 1705, 

 Denys Papin, in an improved form of Dr. Savery's engine, produced what was 

 in effect a non-condensing, single acting steam pump with the steam and water 

 cylinders in one. He utilized a mass of heated metal placed in a recess in the 

 diaphragm or piston, on the steam side, to reduce condensation. As the metal 

 cooled it could be lifted from its position and replaced by another heated mass. 

 The boiler was attached directly to the steam cylinder and Papin's device was 

 essentially a superheater. 



Probably the first practical use of superheated steam was that referred to in 

 the "Life of Richard Trevethick." This book states that in 1828 a Captain 

 MacGregor at a mine in Cornwall, England, spurred by the high duty record of 

 a pumping engine whose cylinder had been insulated with sawdust, built a brick 

 jacket about his cylinder and steam pipe, leaving a chamber between the brick 

 and the metal, and by building a fire within this open space increased the duty of 

 his engine some 50 per cent. Trevethick experimented with this engine and 

 "superheater" and showed a saving in the coal used by the boiler furnishing it 

 steam of approximately 26 per cent. There appears to be no published record 

 of the attention that such an increase in efficiency must have aroused. 



It is recorded that in 1834 John Ericsson made some experiments with 

 superheated steam, but there are apparently no published results. Longridge, in 

 1845, and Rafford, in 1851, also experimented with superheated steam, but the 

 records of both their experiments and results are meager. 



For a period of twenty years after 1850 there was a marked interest on the 

 part of engineers in superheated steam and its use. Hirn, in 1857, conducted a 

 great number of experiments with steam at a pressure of about 35 pounds and 

 with temperatures ranging from 410 to 490 degrees Fahrenheit. His results 

 showed gains of from 20 to 27 per cent, due to the use of superheat. 



B. F. Isherwood, Chief of the Bureau of Steam Engineering, U. S. Navy, 

 first experimented in 1860 with Waterman's "adheater" and an experimental 

 engine, with and without cylinder jacketing, and showed substantial gains due to 

 the increased steam temperatures. While admitting the gain in engine efficiency 

 due to the use of superheat, Isherwood at first was skeptical as to its practical 

 use and declared against its advisability because of difficulties in lubrication, in- 

 jury to cylinders and, with reference to marine practice, because of additional 

 weight. During 1862-1864 he conducted an extensive series of tests on the 



