Facilities and Techniques for Maintaining a Controlled Fluoride Environment in Vegetation Studies

The principle of fabric filtration has only recently been accepted for fossil fuel fired boiler particulate emissions control. Information on design criteria is, therefore, limited. The paper provides data on the few installations where baghouses have been installed and successfully operated. The general conclusion is that a strong relationship exists between air to cloth ratio and bag life.     

New Fabrics and their Potential Application

Considering fabric filtration, particularly the fabrics and their ability to handle submicron particulate and fumes, it is noted that the value of new developments are measured in terms of both improved operational and economic efficiency. The types of available fibers dictate fabric production characteristics as well as the limits of application for the manufactured fabric.     

1985 Update,Operating History and Current Status of Fabric Filters in the Utility Industry

Stringent particulate emissions limits and increasing awareness of stack opacity is leading the utility industry to use high efficiency particulate control systems. In response to this trend, the Electric Power Research Institute (EPRI) is conducting several research programs aimed at improving the operation, maintenance and performance of particulate control systems. One of these programs, RP-1401, “Reliability Assessment of Particulate Control Systems,” is developing operation, maintenance and design data bases for both electrostatic precipitators and fabric filters. This paper discusses some of the intermediate findings of the work done on fabric filters.     

Fibers,Electrostatics, and Filtration: A Review of New Technology

This symposium sponsored by the Fiber Society and the Filtration Society has provided a clear indication that the “black-art” era of filtration has passed or is on its way out. The R & D efforts reviewed here by investigators from diverse disciplines provide evidence that these high efficiency particulate control devices can be made to function not only more consistently at high levels but now with even better control of the fine, health damaging particles. The outstanding improvement in every filtration parameter, reliably attainable by aerosol charging and/or by imposing an electric field on the filter, indicates clearly that fabric filtration has now reached an even higher plateau in particulate control technology.     

Comparative study of spray booth filter system efficiency

During recent years, greater emphasis has been placed on the control of particulate emissions from painting operations. This has gained more importance as more is learned about the potential release of toxic metals to the atmosphere from painting operations. This has led to queries about the efficiency of various painting arrestor systems to reduce particulate discharges to the atmosphere. Even more important is the capability of the arrestor systems to control PM10 emissions. In 1995, the U.S. Environmental Protection Agency initiated a study to evaluate various dry paint overspray arrestor systems. This study was designed to evaluate not only the total emissions control capability of the arrestor but also the PM10 control capability of the various system designs. Paint overspray arrestor systems using five different filtration concepts or materials were selected. They include systems constructed of fiberglass, paper, Styrofoam, and cardboard materials. These systems used filtration techniques incorporating the following filtration phenomena and designs: cyclone, baffle, bag systems, and mesh systems. The testing used an optical particle counting procedure to determine the concentration of particles of a given size fraction to penetrate a test arrestor system. The results of the testing indicated that there are significant differences in the efficiency of the tested system designs to capture and retain PM10. This paper summarizes the results of the research conducted to determine the capability of the arrestor systems to capture particulate of sizes down to approximately 1 micron in surface diameter.     

Optimization of Height of Release of Air Pollutants

A number of key projects in the Environmental Protection Agency (EPA) particulate R&;D program having applicability to industry are presented. For electrostatic precipitators (ESP) there is presented the result of work on large diameter discharge electrodes which provide a decrease in penetration of up to a factor of 4 when compared to conventional small diameter electrodes. Also discussed is the multistage ESP which provides a collection efficiency that would require a collecting plate area 4 or 5 times larger with conventional ESP technology. The E-SOX technology makes use of the multistage concept to free up space in the ESP for SO₂ removals of up to 90%. Electrostatically augmented fabric filtration provides a reduction in pressure drop of about 5 0% as compared to conventional fabric filtration. Wind tunnel modeling of windbreaks for material storage piles indicates a potential for providing engineering design data that would allow significant emission reduction caused by wind erosion     

Continuous Measurement of Diesel Particulate Emissions

Evaluation of emerging diesel particulate emissions control technology will require analytical procedures capable of continuous or “real-time” measurement of transient organic and elemental carbon emissions. Procedures based on the flame ionlzation properties of organic carbon and the opacity or light extinction properties of elemental carbon are described, and applied for measurement of particulate emissions from diesel engines. The Instrumentation provided adequate sensitivity and time resolution for observation of the transient emissions associated with typical automobile urban driving conditions. Analytical accuracy is evaluated by comparing Integrated average results to measurements using classical gravimetric filtration and solvent extraction procedures. Mass specifc extinction coefficients are evaluated using the Beer-Lambert law. A simplified linear model relating elemental carbon concentration to opacity is also evaluated.     

Comparative Study of Spray Booth Filter System Efficiency

ABSTRACT

During recent years, greater emphasis has been placed on the control of particulate emissions from painting operations. This has gained more importance as more is learned about the potential release of toxic metals to the atmosphere from painting operations. This has led to queries about the efficiency of various painting arrestor systems to reduce particulate discharges to the atmosphere. Even more important is the capability of the arrestor systems to control PM₁₀ emissions.

In 1995, the U.S. Environmental Protection Agency initiated a study to evaluate various dry paint overspray arrestor systems. This study was designed to evaluate not only the total emissions control capability of the arrestor but also the PM₁₀ control capability of the various system designs. Paint overspray arrestor systems using five different filtration concepts or materials were selected. They include systems constructed of fiberglass, paper, Styrofoam, and cardboard materials. These systems used filtration techniques incorporating the following filtration phenomena and designs: cyclone, baffle, bag systems, and mesh systems.

The testing used an optical particle counting procedure to determine the concentration of particles of a given size fraction to penetrate a test arrestor system. The results of the testing indicated that there are significant differences in the efficiency of the tested system designs to capture and retain PM₁₀.

This paper summarizes the results of the research conducted to determine the capability of the arrestor systems to capture particulate of sizes down to approximately 1 μm in surface diameter.     

An extended self-organizing map network for modeling and control of pulse jet fabric filters

Pulse jet fabric filters (PJFFs) have become an attractive option of particulate collection utilities, because they can meet stringent particulate emission limits regardless of variation in operating conditions. Despite their wide applications, the present control algorithm for PJFFs can best be described as rudimentary. In this paper, a modeling and control strategy based on the local model network (LMN) is proposed. An extended self-organizing map (ESOM) network is developed to construct the LMN model of the filtration process using the filter's input-output data. Subsequently, these ESOM local models are incorporated into the design of local generalized predictive controllers (GPC), and the proposed controller design is obtained as the weighted sum of these local controllers. Simulation results show that the proposed controller design yields a better performance than both conventional GPC and proportional plus integral (PI) controllers yield.     

Theoretical investigation of pressure drop in combined cyclone and fabric filter systems

Computer simulations were conducted to investigate potential pressure drop reductions obtainable by combining cyclones, as pre-collectors, with fabric filters. The Leith-Licht model was used to characterize cyclone emissions and the specific resistance (K₂) of the fabric filter dust cake was calculated from an empirical correlation. Several important dimensionless groups were identified and evaluated. One group, the product of the ratio of the dust cake specific resistances expected with and without the cyclone and the mass penetration of the cyclone, (K₂/K₂) Pn, indicates whether a pressure drop reduction is possible. A correlation was developed for this group as a function of the size properties of the inlet dust (particle mass median diameter and geometric standard deviation) and the cyclone particle cut diameter. Expressions were derived for the break-even time, the duration of filtration with the cyclone needed to show a pressure drop reduction in comparison with filtration without the cyclone. It is shown that in previously reported experiments and simulations indicating an advantage for the combined cyclone-fabric filter system, filtration cycles were typically longer than the break-even time; those showing no improvement typically had filtration times shorter than the break-even time.     

Monitoring of PM10 and PM2.5 around primary particulate anthropogenic emission sources

Investigations on the monitoring of ambient air levels of atmospheric particulates were developed around a large source of primary anthropogenic particulate emissions: the industrial ceramic area in the province of Castelló (Eastern Spain). Although these primary particulate emissions have a coarse grain-size distribution, the atmospheric transport dominated by the breeze circulation accounts for a grain-size segregation, which results in ambient air particles occurring mainly in the 2.5–10 μm range. The chemical composition of the ceramic particulate emissions is very similar to the crustal end-member but the use of high Al, Ti and Fe as tracer elements as well as a peculiar grain-size distribution in the insoluble major phases allow us to identify the ceramic input in the bulk particulate matter. PM2.5 instead of PM10 monitoring may avoid the interference of crustal particles without a major reduction in the secondary anthropogenic load, with the exception of nitrate. However, a methodology based in PM2.5 measurement alone is not adequate for monitoring the impact of primary particulate emissions (such as ceramic emissions) on air quality, since the major ambient air particles derived from these emissions are mainly in the range of 2.5–10 μm. Consequently, in areas characterised by major secondary particulate emissions, PM2.5 monitoring should detect anthropogenic particulate pollutants without crustal particulate interference, whereas PM10 measurements should be used in areas with major primary anthropogenic particulate emissions.     

Heavy Duty Diesel Particulate Emission Factors

For the past several years, EPA has been measuring particulate emissions from a variety of heavy-duty diesel engines through contracts with Southwest Research Institute. Particulate emissions samples have been collected using an exhaust splitter to divert a fraction of the engine exhaust into a standard dilution tunnel. A small fraction of the diluted exhaust from the tunnel is pulled through a filter from which particulate mass and, in some cases, organic content of the particulate is determined. This paper discusses the sampling system and gives particulate emission factors that have been computed from truck and bus fuel consumption data as well as average truck and bus speed data from New York and Los Angeles (freeway and nonfreeway usage). Average particulate emission test results (steady state tests) for 2-stroke engines were 4.74 g/kg fuel and for 4-stroke engines were 2.64 g/kg fuel. Using average particulate emissions results, a particulate emission factor range of 0.8 to 1.3 g/km was computed. Nationwide diesel particulate emissions were calculated to be 88,000 metric tons per year.     

Filtration Properties of Fly Ash from Fluidized Bed Combustion

Some of the features of the fluidized-bed combustion (FBC) process have a direct bearing on the particulate properties that most strongly influence filtering pressure drop. A laboratory program was conducted to experimentally determine the relative pressure drop characteristics of ashes from the TVA-EPRI 20-MW bubbling bed, atmospheric pressure FBC (AFBC) pilot plant and six pulverized-coal combustion (PC) units. The combined influences of measured particle and dust cake properties on filtering pressure drop were estimated with existing filtration theories. These theories predict a higher pressure drop for a dust cake produced with the AFBC ash than for one consisting of any of the PC ashes. Laboratory measurements were made of the flow resistance of idealized, simulated dust cakes to confirm these predictions. Field operating data from the fabric filters collecting some of the tested ashes were available to validate the laboratory results. The laboratory and field data show relatively good agreement. The AFBC ash must be treated as a special case for fabric filters, and careful selection of cleaning method and fabric must be made to minimize the inherently high pressure drop characteristics of this ash.     

An Extended Self-Organizing Map Network for Modeling and Control of Pulse Jet Fabric Filters

ABSTRACT

Pulse jet fabric filters (PJFFs) have become an attractive option of particulate collection utilities, because they can meet stringent particulate emission limits regardless of variation in operating conditions. Despite their wide applications, the present control algorithm for PJFFs can best be described as rudimentary. In this paper, a modeling and control strategy based on the local model network (LMN) is proposed. An extended self-organizing map (ESOM) network is developed to construct the LMN model of the filtration process using the filter's input-output data. Subsequently, these ESOM local models are incorporated into the design of local generalized predictive controllers (GPC), and the proposed controller design is obtained as the weighted sum of these local controllers. Simulation results show that the proposed controller design yields a better performance than both conventional GPC and proportional plus integral (PI) controllers yield.     

Participate and Gaseous Emissions from Natural Gas Furnaces and Water Heaters

Three furnaces and one hot water heater were tested for particulate and gaseous emissions. The effects of fuel, stoichiometry, operating conditions, and appliance type on emission levels were studied. The filterable particulate levels from a properly operating furnace were very low. However, condensable particulate emissions were considerably greater, approximately the same as predicted by EPA estimates of furnace particulate emissions. Carbon emissions comprised about 12% of filterable particulate emissions. However, when operated highly fuel-rich, copious amounts of elemental carbon particles were emitted with a mass median diameter of less than 0.4 μm. Gaseous emissions were dependent on cycling of the furnace and stoichiometry.

An estimate was made of the daily furnace emissions compared to daily emissions from a 1980 catalyst-equipped automobile. While gaseous emissions were less than the corresponding vehicle emissions, the particle emissions from the furnace were three times greater than particle emissions from a 1980 vehicle.     

Determination of zinc speciation in basic oxygen furnace flying dust by chemical extractions and X-ray spectroscopy

There is a growing concern regarding the environmental and public health risks associated with airborne particulate matter (PM). The basic oxygen furnace is one of the most important atmospheric dust sources of the steel manufacturing process. It emits dust enriched in heavy metal such as Zn, which is assumed to contribute to the toxic potential of atmospheric PM. Dust collected before and after the filtration system was analyzed to determine Zn speciation. To this end, a variety of analytical tools were used and a sequential extraction protocol has been specifically developed for iron and steel dust. The Zn speciation results obtained by EXAFS and sequential extraction were in excellent agreement. Before filtration, the speciation of Zn in BOF was 43% ZnFe₂O₄, 23% ZnCO₃ and 16% ZnO. The same species were detected after filtration with different proportions. BOF dust after filtration contains more soluble Zn phases which may play a role in the toxic effects of the emissions.     

Combustion Mechanisms in Wood Fired Boilers

The emissions from combustion of wood residue fuel in an experimental spreader-stoker boiler were measured at the Fairplay Test Facility at Oregon State University. Stack gases were monitored to determine levels of excess air, opacity, and particulate loading. Particulate emissions were measured to determine the effects of underfire air flow rate and fuel bed depth on particulate carry over rate. An experiment conducted at four energy release rates and two fuel bed depths indicated that increased bed depth has the effect of reducing particulate emissions and that the effect increases as energy release rate increases. The experiment also showed increased energy release rate has the effect of increasing particulate emissions. The effects were found to be statistically significant.     

关中地区机动车颗粒物排放清单

利用本地化修正的MOVES模型模拟确定了关中地区不同类型车辆的颗粒物排放因子,结合实地调研的保有量和行驶里程数据测算了该地区的机动车颗粒物年排放总量,并从季节、城市、车型和燃油等多个角度详细分析了颗粒物的排放分担率。结果表明：关中地区2012年的机动车颗粒物排放总量分别为PM2.5 4.06×103 t,PM10 5.52×103 t;关中五市一区中西安市的颗粒物排放量最高,PM2.5和PM10排放分别占到该地区的46.53%和48.39%;不同类型车辆中,重型货车的排放分担率最高,其次为中型货车,二者之和占到颗粒物总排放的50%以上;不同燃油车辆中,柴油车的排放分担率远远高于汽油车,是颗粒物的主要贡献者;因此中型和重型柴油货车是关中地区控制颗粒物排放污染的重点车型。     

Model calibration for pressure drop in a pulse-jet cleaned fabric filter

A model based on Darcy's law allows prediction of pressure drop in a pulse-jet cleaned fabric filter. The model considers the effects of filtration velocity, dust areal density added during one filtration cycle, and pulse pressure. Data used to calibrate the model were collected in experiments with three fabric surface treatments and three dusts conducted at three filtration velocities, for a total of 27 different experimental conditions. The fabric used was polyester felt with untreated, singed, or PTFE-laminated surface. The dusts used were granite, limestone and fly ash. Filtration velocities were 50,75 and 100 mm s⁻¹. Dust areal density added during one filtration cycle was constant, as was pulse pressure. Under these conditions, fabric surface treatment alone largely determined the values for two of the three constants in the model; the third constant depends on pressure drop characteristics of the venturi at the top of each filter bag.     

Emissions from Burning Grass Stubble and Straw

The emissions from burning the residue following grass-seed harvest were determined by means of a combined laboratory-field study. Samples of the straw and stubble residue were burned in the laboratory burning tower at the University of California at Riverside. Complete analyses were determined for gaseous and particulate emissions for the important grass species from the Willamette Valley of Oregon. Particulate emissions averaged 15.6 lb/ton of fuel burned. Carbon monoxide averaged 101 lb/ton of fuel burned. Hydrocarbon emission averages, in pounds per ton of fuel burned, were 1.74 for saturates plus acetylene, 2.80 for defines, and 1.68 for ethylene. The NO_x emission, at the temperature peak during the burn, averaged 29.3 ppm. Field studies, conducted by personnel from Oregon State University, measured only particulate emissions, carbon dioxide, and temperature over the burn. The carbon dioxide values were found to be similar to those obtained on the burning table at UCR and it was therefore concluded that the other gaseous emissions were similar and could be used as reasonably accurate for emission inventories. The temperature values obtained in the laboratory and field were also similar and further justifies extrapolating the burning table data to field situations. The particulate matter collected in the field studies averaged 15.55 lb of particulate per ton of fuel burned. This is the same average obtained for the burning table data which again serves to validate the emissions reported from Riverside. Much more variability was found in the particulate emissions obtained in the field which reflects the wider range of environmental conditions encountered in the field.