Mercury Balance on a Large Pulverized Coal-Fired Furnace

This paper presents results of a survey of mercury concentrations in coal, ash, water, fly ash, and flue gas discharges from a 5.5 × 10⁶ Ib/hr steam generator serving a 775 MW (net) turbine-generator set. Representative composite or grab samples were obtained for inlet coal and outlet ash and water. Stack samples were obtained for fly ash and mercury vapor emissions while the unit was operated at 660 MW (net) (85% of full load). Samples were analyzed by anodic stripping voltammetry, plasma emission spectroscopy, and neutron activation analysis to determine mercury concentration entering the furnace in the coal and leaving the furnace in the flue gas, fly ash, bottom and hopper ash, and water. Method inter-comparisons are discussed. A material balance for mercury has been calculated from fuel, ash, and stack gas flow rates. About 90% of the mercury in the coal is released and appears as vapor discharged in the stack gas while 10% remains in the residual ash. For a 700 MW (net) unit, about 5 lb/day of mercury vapor is released to the atmosphere.     

Rural and Urban Ozone Relationships In New York State

High ozone concentrations, often in excess of the national ambient air quality standard for photochemical oxidants, have been measured simultaneously in urban and rural areas of New York State. Average daily rural ozone concentrations were found to correlate well with daily maximum urban ozone concentrations suggesting a common source. Estimations of the quantity of ozone advectively transported into New York State are more than an order of magnitude greater than estimations of the potential photochemical generation of ozone from hydrocarbon emissions within New York State. It is suggested thai the high rural ozone levels are not primarily due to the transport of ozone and ozone precursors from olher urban areas, but are rather due to natural phenomena such as photochemical generation from naturally occurring precursors or transport of ozone from the stratosphere to the troposphere. The effectiveness of a hydrocarbon control strategy for New York State to meet the ambient air quality standard for photochemical oxidants when background levels themselves may be above the standard is questioned.     

Low Emissions from Controlled Combustion for Automotive Rankine Cycle Engines

Rankine cycle engines have a high potential for meeting the emission levels established by the 1970 amendment to the Federal Clean Air Act for the 1975-76 automobile. This paper discusses a Solar research and development program sponsored by EPA/APCO which demonstrates a full scale 2 million Btu per hour working model of a Rankine cycle engine combustor and controls which can surpass the emission goals established.

Special features of the combustor are the unique methods of precisely controlling both the fuel and air to provide optimum flame performance at any engine power level. This paper discusses the special requirements of the Rankine cycle engine and shows why the very wide range of fuel flow required necessitates use. of special techniques in fuel atomization, fuel and air control, and aerodynamics. Sufficient discussion is included to show the design methods that are necessary, in general, to achieve low emissions in continuous flow combustion systems. Emphasis is placed on the importance of interfacing a combustion system with other engine parts if a successful low emission, wide turndown ratio combustor working model is to be achieved. Sufficient discussion on combustion kinetics is included to advise on approaches necessary to minimize NO formation in external combustion systems while maintaining high efficiency and low CO and unburned hydrocarbons.     

Note on In-Traffic Measurement of Airborne Tire-Wear Participate Debris

Measuring greenhouse gas (GHG) source emissions provides data for validation of GHG inventories, which provide the foundation for climate change mitigation. Two Toyota RAV4 electric vehicles were outfitted with high-precision instrumentation to determine spatial and temporal resolution of GHGs (e.g., nitrous oxide, methane [CH₄], and carbon dioxide [CO₂]), and other gaseous species and particulate metrics found near emission sources. Mobile measurement platform (MMP) analytical performance was determined over relevant measurement time scales. Pollutant residence times through the sampling configuration were measured, ranging from 3 to 11 sec, enabling proper time alignment for spatial measurement of each respective analyte. Linear response range for GHG analytes was assessed across expected mixing ratio ranges, showing minimal regression and standard error differences between 5, 10, 30, and 60 sec sampling intervals and negligible differences between the two MMPs. GHG instrument drift shows deviation of less than 0.8% over a 24-hr measurement period. These MMPs were utilized in tracer-dilution experiments at a California landfill and natural gas compressor station (NGCS) to quantify CH₄ emissions. Replicate landfill measurements during October 2009 yielded annual CH₄ emissions estimates of 0.10 ± 0.01, 0.11 ± 0.01, and 0.12 ± 0.02 million tonnes of CO₂ equivalent (MTCO₂E). These values compare favorably to California GHG Emissions Inventory figures for 2007, 2008, and 2009 of 0.123, 0.125, and 0.126 MTCO₂E/yr, respectively, for this facility. Measurements to quantify NGCS boosting facility-wide emissions, during June 2010 yielded an equivalent of 5400 ± 100 TCO₂E/yr under steady-state operation. However, measurements during condensate transfer without operational vapor recovery yield an instantaneous emission rate of 2–4 times greater, but was estimated to only add 12 TCO₂E/yr overall. This work displays the utility for mobile GHG measurements to validate existing measurement and modeling approaches, so emission inventory values can be confirmed and associated uncertainties reduced.

Implications:?Measuring greenhouse gas (GHG) source emissions provides data and validation for GHG inventories, the foundation for climate change mitigation. Mobile measurement platforms with robust analytical instrumentation completed tracer-dilution experiments in California at a landfill and natural gas compressor station (NGCS) to quantify CH₄ emissions. Data collected for landfill CH₄ agree with the current California emissions inventory, while NGCS data show the possible variability from this type of facility. This work displays the utility of mobile GHG measurements to validate existing measurement and modeling approaches, such that emission inventory values can be confirmed, associated uncertainties reduced, and mitigation efforts quantified.     

A Fast Gas Chromatographic Method for Measuring C2-C6 Alkanes and Alkenes in Air

The Environmental Protection Agency is responsible for establishing, reviewing, and revising standards of performance for new stationary sources of air pollution. Since this federal program was authorized in 1970, standards of performance (commonly referred to as new source performance standards or NSPS) have been developed for 34 categories of stationary sources. These regulations have focused primarily on large new sources of particulate matter, NO _x , and SO₂ emissions. Recently, work has begun on NSPS for a number of source categories that emit volatile organic compounds. Environmental professionals in these industries and in many regulatory agencies have little direct experience with the NSPS program and are unaware of the detailed engineering, cost, and economic information available with each proposed rulemaking. This article, therefore, reviews the purposes, procedures, and benefits of the NSPS program. A summary of the NSPS that have been promulgated through February 1983 are presented in tabular form.     

Emissions Control and Ambient Air Quality at a Secondary Steel Production Facility

Steel production from electric arc furnaces has been continuously rising over the past few years. The trend is expected to continue due to both the anticipated increase in demand for steel, and to the replacement of obsolete open hearth furnaces. In 1972 steel produced in electric arc furnaces, which makes up 25 to 30% of the annual United States steel production, was produced primarily from recycled scrap steel in approximately 300 electric arc furnaces operated by 99 companies at 121 locations.¹ Over half of these furnaces are smaller than 50 tons, and many are located in small bar mills producing a variety of merchant steel products.     

Field Reliability of the Orsat Analyzer

Results from four field based collaborative tests and from one laboratory based collaborative test of the Orsat analytical procedure are discussed. The results from the five collaborative tests demonstrate that routinely using Orsat data to convert particulate emissions from combustion sources to the reference conditions of 50 % excess air and 12% carbon dioxide may introduce sizeable errors in the corrected particulate loading. Ways to improve the Orsat apparatus and increase the reliability of the data are suggested.

Also reported are the results from field and laboratory studies on the reliability of using individual carbon dioxide and oxygen analyzers of the Fyrite* type to determine stack gas molecular weight. The laboratory study, which was done using three cylinders containing mixtures of carbon dioxide, oxygen, carbon monoxide, and nitrogen of known concentration, determined that these analyzers give carbon dioxide and oxygen analyses of sufficient reliability to yield accurate molecular weights. The results of the field studies, which were done on actual flue gas samples, also support this conclusion.     

The Value of Continuous Monitoring to the User

Potential benefits of a continuous monitoring program are presented in the form of questions that can be asked in connection with the information gained from the program. These questions are:

1. Are there process problems of which we are unaware?

2. Will this information be useful in the design of the next plant?

3. Can the information be used for improved process control?

4. Are we losing valuable material?

5. Can we use this information to modify our process for reduced pollution?