HEAT CONSUMPTION AND HEAT UTILIZATION. 



505 



Estimates and Tests of Heat Distribution. 



Various estimates of the heat requirements of cement-manufacture 

 have been presented by different authors, and several actual tests have 

 been made of heat distribution in the rotary kiln. The principles on 

 which these calculations are based have been discussed in the preceding 

 pages, and the estimates and tests in question will now be presented 

 for comparison. 



Newberry's estimates. Some years ago Prof. Newberry published 

 a discussion of the question of fuel consumption which leaves little to 

 be desired even in spite of recent changes in rotary practice. His 

 results are summarized in Table 191. 



TABLE 191. 

 NEWBERRY'S ESTIMATES ON HEAT DISTRIBUTION IN KILNS. 



Helbig's estimates. Very recently Mr. A. B. Helbig has discussed 

 this question, but only incidentally to a subject of more importance, i.e., 

 the utilization of waste heat. Mr. Helbig's figures, slightly rearranged 

 for convenience of comparison, will be found in Table 193 on page 509. 



Results of actual tests. It might be supposed that actual tests of 

 the thermal efficiency of the rotary kiln could be readily made, and 

 that the results of these tests would afford data of great value to the 

 manufacturer. To a certain extent this is true, but, unfortunately, the 

 results afforded by such tests require interpretation, and this in turn 

 requires that certain chemical constants so called by courtesy should 

 be employed as bases. These constants are, for example, the heat of 

 dissociation of the carbonates and the sulphates, of the decomposition 

 of clay, of the formation of lime silicates and aluminates, etc. The 



