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Published in Mary K. Theodore, Louis Theodore, Introduction to Environmental Management, 2021
Selective non-catalytic reduction (SNCR) involves injecting ammonia or urea into the flue gas to yield nitrogen and water. The ammonia or urea must be injected into specific high-temperature zones in the upper furnace or convective pass for this method to be effective.
Extractable and Plant Concentrations of Metals in Amended Coal Ash
Published in Robert F. Keefer, Kenneth S. Sajwan, Trace Elements in Coal and Coal Combustion Residues, 2020
The coal-burning power plant at LaCygne, KS, is jointly owned and operated by the Kansas City Power and Light Company (KCPL) and Kansas Gas and Electric (KGE) and currently has two coal-fired boiler and generating units. LaCygne generating unit No. 1 is designed to burn eastern coal, which is high in S and ash. Unit 1 uses a fluid limestone suspension as the scrubbing system. Approximately 120,000 m3 (96 ac-ft) of black, glassy bottom ash and 420,000 m3 (335 ac-ft) of FGD sludge are produced annually. Generating unit No. 2 burns low-S western coal and is not equipped with a desulfurizing system. Particulate matter (fly ash) is removed from flue gases by an electrostatic precipitator. This unit produces 16,000 m3 (13 ac-ft) of a light-brown, alkaline bottom ash and 45,000 m3 (36 ac-ft) of highly alkaline fly ash per year. KCPL is attempting to revegetate the ash without the usual addition of a covering layer of topsoil. It was determined that satisfactory plant covers could be established by mixing the ash with small quantities of soil and manure, adequate fertilization, and proper selection of plant species. After three years, excellent stands and aerial cover were attained.
Control Strategies and Applicable Technologies
Published in Winston Chow, Katherine K. Connor, Peter Mueller, Ronald Wyzga, Donald Porcella, Leonard Levin, Ramsay Chang, Managing Hazardous Air Pollutants, 2020
The fraction of the total ash reaching the pollution control devices depends on plant design. In some plants bottom ash may account for a significant fraction of the ash; in other plants it may be negligible. In most power stations >99% of the particulates are removed from the flue gases using electrostatic precipitators (ESP), fabric filters (baghouses), or wet scrubbers. This implies that most (>95%) of the trace elements are also removed. Although precipitators, baghouses, and scrubbers are all capable of high overall collection efficiencies, it is generally true that they are least effective for smaller particle size range (<5 mm).5 Thus, a small proportion of the fly ash penetrates the particulate control systems and reaches the atmosphere with the stack gases.
Density Functional Theory Study on the Reduction of NO by CO Over Fe3O4 (111) Surface
Published in Combustion Science and Technology, 2022
Lilin Hu, Yang Zhang, Qing Liu, Hai Zhang
NOx is one of the main pollutants generated by fuel combustion. To strictly control the NOx emission, selective catalytic reduction (SCR) or selective non-catalytic reduction (SNCR) techniques are often used for flue gas treatment (Yue et al. 2020). Though working effectively, both techniques use ammonia or urea as reducing agents. These agents are feedstocks of agricultural fertilizer and other chemicals, and their transport and storage need special care, especially for those near-city power plants. In addition, the over-use of reducing agent or poor mixing between reducing agent and flue gas can often cause NH3-slip and aggravate ash deposition on the air preheater (Cheng et al. 2018). Moreover, for SCR, precious and hazardous metals such as vanadium and tungsten are used as the catalyst (Qin et al. 2016). Therefore, CO-SCR technology, which uses CO instead of NH3 as reductant, was proposed (Boningari et al. 2018).
Experimental investigation on thermal conductivity of fly ash nanofluid and fly ash-Cu hybrid nanofluid: prediction and optimization via ANN and MGGP model
Published in Particulate Science and Technology, 2022
Praveen Kumar Kanti, K. V. Sharma, Zafar Said, Mehdi Jamei, Kyathanahalli Marigowda Yashawantha
The fly ash produced by coal combustion is carried in the flue gases as dust. These flue gases pass through an electrostatic precipitator (ESP), which absorbs the majority of the dust. The particles in the gas stream coming out of the boiler after coal combustion are electro-statically charged by precipitators. The charged particles are then directed to the collector plates and deposited there. A rapping hammer is used to clear the dust that has accumulated. Typically, micron-sized fly ash is deposited at the ESP. Fly ash was collected at the ESP (Model: ISGEC) of the 32 MW Vijaynagar cogeneration power plant, which uses Indonesian coal, in Mundaragi, Gadag District, Karnataka, India. These particles subjected to a ball friction (Model: PM-100, Retch, Germany) process for 60 h to obtain an average particle size of 14.5 nm. Due to the ball milling effect, the surface area of fly ash particles increased (Kanti, Sharma, Said, and Bellos 2020).
Public health impact of coal-fired power plants: a critical systematic review of the epidemiological literature
Published in International Journal of Environmental Health Research, 2021
Flue gas desulfurization (FGD) is a process by which fly ash containing particulates and SO2 is removed through an absorbent material such as limestone (Srivastava and Jozewicz 2001). Since 1997 FGD equipment has been gradually installed at all 13 units of the Mae Moh coal-fired power plant in northern Thailand. By utilizing an impact pathway approach, Thanh and Lefevre (2001) studied the potential health benefits of reducing PM10 and SO2 emissions following the FGD installation. Installation of FGD units at the Mae Moh power plant resulted in a 98% reduction of SO2 and 60% reduction of PM emissions. The authors estimated that reduction of emissions in just one of the 300-MW coal-fired units resulted in an annual decrease of 16 cases of acute mortality, 12 cases of respiratory and cardiac hospital admissions, and approximately 354,000 fewer days with acute respiratory symptoms annually. In monetary terms, the benefit was equivalent to US $18.2 million (1995 prices) annually. When extended across all 13 units the total direct health savings would be $159.25 million annually. The study only assessed decreased morbidity and mortality associated with decreased PM and SO2 emissions and did not estimate PAH and metal emission decrease and did not quantify cancer-related health effects.