Operation & Maintenance of Tailings Earth En Dam Specially For Disposal of Fly Ash from Thermal Power Stations
Several tailings earthen dams have failed during monsoon. Due to failure of tailings dam, stored tailings waste gets release in downstream area causing environmental hazard. Ash produced by combustion of coal in thermal power stations are stored in ash pond. No well-defined provision of operation and maintenance exists for ash pond. Therefore, this paper describes various issues related to operation and maintenance of ash pond.
DENSIFICATION OF DEPOSITED ASH SLURRY
In India, ash content in coal is usually high and percentage utilization for construction is limited. As a result, about 90 to 95 percentage of the ash generated has to be deposited in ash pond. The present ash generation is about 75 million tonnes and it is likely to exceed I 00 million tonnes by the end of this century. During the last decade, several laboratory studies have been made on densification of deposited ash slurry by vibration, application of vacuum, electro osmosis, etc. In last few years, with assistance from Department of Science and Technology, field experiments have been carried out to densify the deposit by vtbro flotation technique and also by explosives. This paper describes brief literature review on the subject andsummary of compaction achieved in field by vibroflotation as well as explosives. Based on the study canied out so far, it appears that densification in ash pond is very effective for rehabilitation of the area for housing or other use. It also eliminates chan~ Qf liquefaction during earthquake.
Techno-economic analysis of chemical looping combustion with humid air turbine power cycle
Abstract Power generation from fossil fuel-fired power plant is the largest single source of CO2 emission. CO2 emission contributes to climate change. On the other hand, renewable energy is hindered by complex constraints in dealing with large scale application and high price. Power generation from fossil fuels with CO2 capture is therefore necessary to meet the increasing energy demand, and reduce the emission of CO2. This paper presents a process simulation and economic analysis of the chemical looping combustion (CLC) integrated with humid air turbine (HAT) cycle for natural gas-fired power plant with CO2 capture. The study shows that the CLC–HAT including CO2 capture has a thermal efficiency of 57% at oxidizing temperature of 1200 °C and reducer inlet temperature of 530 °C. The economic evaluation shows that the 50 MWth plant with a projected lifetime of 30 years will have a payback period of 7 years and 6 years for conventional HAT and CLC–HAT cycles respectively. The analysis indicates that CLC–HAT process has a high potential to be commercialised.