The Effect of Coal Combustion Flue Gas Components on Low-Level Chlorine Speciation Using EPA Method 26A

Abstract

U.S. Environmental Protection Agency (EPA) Method 26A is the recommended procedure for capturing and speciating halogen (X 2 ) and hydrogen halide (HX) stack emissions from combustion sources. Previous evaluation studies of Method 26A have focused primarily on hydrogen chloride (HCl) speciation. Capture efficiency, bias, and the potential interference of Cl 2 at high levels (>20 ppm [µg/m 3 ]) and NH 4 Cl in the flue gas stream have been investigated. It has been suggested that precise Cl 2 measurement and accuracy in quantifying HX or X 2 using Method 26A are difficult to achieve at Cl 2 concentrations <5 ppm; however, no performance data exist to support this. Coal contains low levels of Cl, in the range of 5-2000 ppmw, which results in the presence of HCl and Cl 2 in the products of combustion. HCl is the predominant Cl compound formed in the high-temperature combustion process, and it persists in the gas as the products of combustion cool. Concentrations of Cl 2 in coal combustion flue gas at stack temperatures typically do not exceed 5 ppm. For this research, bench-scale experiments using simulated combustion flue gas were designed to validate the ability of Method 26A to speciate low levels of Cl 2 accurately. This paper presents the results of the bench-scale tests. The effect of various flue gas components is discussed. The results indicate that SO 2 is the only component in coal combustion flue gas that has an appreciable effect on Cl 2 distribution in IMPLICATIONS The presence of Cl-containing species in combustion effluents is of concern because their emission to the atmosphere can lead to the formation of pollutants such as dioxins and certain Hg compounds. EPA Method 26A is the recommended procedure for measuring the gaseous Cl species HCl and Cl gas in the products of combustion. This study evaluates the effect of SO 2 and other simulated coal combustion flue gas components on the accuracy of EPA Method 26A on the basis of bench-scale tests where low levels of Cl gas were spiked into the flue gas stream. The results indicate that Method 26A cannot speciate low levels of Cl accurately in a coal combustion flue gas stream without modification.Method 26A impingers, and that Method 26A cannot accurately speciate HCl and Cl 2 in coal combustion flue gas without modification. BACKGROUNDSampling and quantitation of stack gas emissions from hazardous waste combustors and from boilers and industrial furnaces co-firing hazardous waste are required as part of the Resource Conservation and Recovery Act (RCRA) permitting process. HCl and Cl 2 are currently regulated. Under RCRA, HCl emissions from municipal incinerators are regulated. Both HCl and Cl 2 are listed among the 189 hazardous air pollutants (HAPs) in the Clean Air Act Amendments of 1990.

Effects of existing energy saving and air pollution control devices on mercury removal in coal-fired power plants

“…The coal was burned in a drop tube furnace with an excess air factor of 1.18 and furnace temperature of 1700°C. EPA Method 26A was used to measure the gaseous Cl contained species, like HCl and Cl 2 , in the flue gas [25]. The Cl species were collected by 0.1 N H 2 SO 4 solution and 0.1 N NaOH solution.…”

Effects of Air Pollution Control Devices on the Chlorine Emission from 410 t/h Circulating Fluidized Bed Boilers Co-firing Petroleum Coke and Coal

“…U.S. EPA Method 26A was employed in the flue gas sampling process of chlorine, which is the recommended method for measuring the gaseous chlorine species, including HCl, Cl 2 , and particulate-bound chlorine (Cl p ), in the flue gas of combustion . Isokinetic samplings were performed to collect sufficient gas volume and particulate matter from the flue gas stream.…”

“…U.S. EPA Method 26A was employed in the flue gas sampling process of chlorine, which is the recommended method for measuring the gaseous chlorine species, including HCl, Cl 2 , and particulate-bound chlorine (Cl p ), in the flue gas of combustion. 22 Isokinetic samplings were performed to collect sufficient gas volume and particulate matter from the flue gas stream. The gas sample was extracted from the flue gas stream through a probe equipped with a quartz fiber filter (maintaining the temperature at 120−134 °C), followed by a series of impigners in an ice bath box.…”

Inner Relationship between CO, NO, and Hg in a 6 kWth Circulating Fluidized Bed Combustor under an O2/CO2 Atmosphere

“…The total input of mercury is the total amount of mercury in the coal, and the total output of mercury is the sum of mercury in flue gas, fly ash, and bottom ash. If mercury mass balances are within the range of 70–130%, all of these data based on the experiments with the OHM and U.S. EPA method 26A would be accurate.…”