Journal of Energy Engineering

Coal combustion by-products (CCBs) have beneficial properties that are currently underutilized. Prudent evaluation of CCBs prior to alternative use application is in the best interest of the party undertaking the project. Ignorance and misunderstanding can lead to environmental harm and may result in unnecessary obstacles and undue regulation. With this consideration in mind, an alkaline injection treatment (AIT) evaluation was undertaken in order to select the most appropriate CCB to treat acid mine drainage (AMD). The information generated from this study also provides insight to the suitability of the CCBs for such alternative uses as neutralization of acidic industrial wastes and soil liming applications in an agricultural setting. Although there is variability in CCB composition due to parent material and operating conditions, general patterns are apparent from this work. With respect to AIT, CCBs with high alkaline contents, nonsetting characteristics, and low exchangeable toxic constituents are the most effective and desirable.

This research has focused on three environmental issues: (1) fugitive dust emissions; (2) water management; and (3) operational parameters (such as thermal efficiency) of aging coal-based thermal power plants, using a case study. Regarding dust emissions, it was observed that the identified sources are fugitive in nature and contribute to a significant loss of raw material and particulate emissions. These sources include coal dust emissions from a wagon tippler area, ball mill operations, and leakage from the ash hoppers of electrostatic precipitators. In situ measurements of air quality and meteorological measurements were undertaken to estimate the emissions from a wagon tippler area, and a mass balance technique was applied across other operations to estimate the emissions. These fugitive emissions were about 98% of the total particulate emissions and the remaining 2% emissions were from the stack. The losses of water in various unit operations were also examined. The sources of water losses include the clariflocculator, the demineralization plant, and auxiliary water cooling of motors and pumps. The operational parameters such as auxiliary power requirement and thermal efficiency that indirectly affect the environment were also studied. The auxiliary power requirement was estimated as 9 MW against the accepted requirement of 7 MW. The thermal efficiency of the plant was estimated to be 26%, against the acceptable level of 32% of such plants in India. This study suggests that a significant reduction in cost and improvements in the environment could be achieved if the plant could be operated at rated efficiencies. It was observed that nonpoint (fugitive) sources, although significant, are ignored.