The results of the mass balance go a long way in confirming the emissions testing. We have confirmed that zinc and phosphorus are almost exclusively retained in the clinker. Lead is retained to a large extent in the clinker, and bromine is partly retained in the clinker and partly collected in the by-pass dust. It should be realized that in this study we were dealing with low concentrations of elements in a large quantity of material. The raw meal, for example, is fed to the system at approximately 5,000 TPD, and an error of 0.0001 percent in the analysis yields an error of 10 pounds per day for that element. Thus, no attempt should be made to equate small material balance losses with true losses from the process. An idea of the overall retention and disposition of each element can, however, be gained from the mass balance. Discussion What is important in the present study is a comparison with other available methods of disposal of used oil. Methods such as disposal into sewers or road oiling do nothing to eliminate the hazard of potential pollutants. Acid-clay treatment leaves a sludge which is itself a disposal problem. Burning in conventional oil burners releases much of the lead into the atmosphere during normal operation; the remainder is released during soot blowing. It One study [8] has been reported of burning used oil in coal-fired boilers. was found that much of the lead was retained in the fly ash during burning with coal, although not as high a proportion as in cement clinker. In all of these studies, only lead emissions were recorded. A comparison of the relative proportions of lead emitted for the St. Lawrence study, two studies on oilfired boilers (Humble [3] and Shell [9]), and a study on a coal-fired boiler is givën in table 3. Table 3. Comparison of Lead Emissions During Waste Oil Burning at St. Lawrence Cement with Other Types of Combustion The St. Lawrence Cement Company has found the burning of used oil to be economically viable. It is necessary to have adequate storage capacity to accept used oil during kiln shutdowns. Large storage capacity is also desirable so the quality of oil fed to the kiln is more uniform. Since the study, the company has installed 2 x 250,000 storage tanks with the necessary pumps and piping to burn up to 21,000 gallons per day of used oil. Conclusions Since all other studies were concerned only with lead release, this can be the only basis of comparison for environmental aspects. The burning of used oil in a cement kiln removes from the environment a higher proportion of the lead than other means of disposal presently available. Since cement production requires high heat input, the use of used oil in cement kilns is attractive from an energy conservation standpoint. Also, there is a cement plant near practically every major center, and these are, of course, the areas where used oil is concentrated. Our study was on a dry process preheater kiln. In respect to removal of volatile components from kiln gases, the preheater is a more efficient scrubber than a straight kiln. It is anticipated that similar results will be obtained with other kiln systems, as long as the dust collection efficiency is adequate. References [1] Refined Petroleum Products, Catalogue No. 45-208 (Statistics Canada, 1974). [2] Refined Petroleum Products, Catalogue No. 45-208 (Statistics Canada, 1975). [3] Skinner, D. J., Preliminary Review of Used Lubricating Oils in Canada, [4] [5] [6] [7] [8] Economic and Technical Review Report No. EPS 3-WP-74-4 (Water Pollution Control Directorate, Environmental Protection Service, Environment Canada, 1974). A Technical and Economic Study of Waste Oil Recovery, Part IV, EPA No. 68-012904 (Teknekron, Inc., 1975). Berry, E. E., MacDonald, L. P., and Skinner, D. J., Experimental Burning of Standard Reference Methods for Source Testing: Measurement of Emissions of Source Testing Code (Ministry of the Environment, Province of Ontario, Air Northern States Power Company, private communication. [9] Final Report of the Task Force on Used Oil Disposal, API Publication No. 4036. National Bureau of Standards Special Publication 556. Proceedings of INDUSTRIAL OILS USED AS FUEL John W. Swain, Jr. 40 Denton Road Wellesley, Massachusetts 02181 U.S. industry uses more industrial oil than automotive and aviation lubricants. Use in 1975 was 1.58 billion gallons of industrial oils and 1.27 billion gallons of automotive and aviation oils [1]. In addition, the gap becomes larger each year and, with samller automobiles and longer drain intervals, will probably continue to increase. One estimated but incomplete breakdown of industrial oil sales for 1975 (but probably applicable to 1977) shows [2]: A recent estimate of industrial oil use in 1977 and projected use in 1981 is shown in table 1 [3]. It is estimated that 481 million gallons is recoverable. This estimate is based on recoverability factors used in the Environmental Protection Agency (EPA) Waste Oil Study, Report to the Congress, April 1974. The National Petroleum News Fact Book (1977) has published the following estimates [4]: There is a trend toward use of synthetic fluids for metalworking and hydraulic and circulating systems, and I expect this to continue, as well as the use of dualpurpose hydraulic and metalworking fluids. A larger fraction of the hydraulic oils used is lost through leakage before it is unsuitable for hydraulic systems. Therefore, industry will try to minimize this loss which would reduce the disposal problem. 1 Underlined numbers in brackets indicate the literature references at the end of this paper. |