Power absorbed in making a barrel of Portland Cement

Review of the Subject. — During the year 1920 the total production of Portland Cement in the United States was 99,694,000 barrels. Of this amount 25,197,000 barrels or, approximately, 25 per cent were made in the Lehigh District, or in the plants located in Eastern Pennsylvania, and New Jersey. On account of the industrial depression the production for the year 1921 was somewhat lower than that stated above. If we assume that one barrel of cement is made with an expenditure of energy amounting to 16 kw-hr., it will be seen that there is required in the 20 mills which comprise the plants in the Lehigh district, an aggregate load of approximately 46,000 kw. to make the 25,197,000 barrels for one year. These figures are interesting in view of the fact that so much thought is being expended today on the superpower system. It is well to remember, however, that about 80 per cent of the total energy required to make a barrel of Portland cement can be obtained by utilizing the heat in the waste gases from the rotary kilns; the balance, or 20 per cent, will have to be either generated by ordinary methods, or purchased from power companies. At the present time comparatively few cement plants are utilizing the waste heat from the rotary kilns, but from the success which has been obtained by those who installed the waste heat system, there is every indication that before long the major portion of the power required in cement plants will be obtained from the heat now carried off in the stack gases.