Analysis of an APCA Baghouse Operation and Maintenance Survey

Baghouse operation and maintenance is probably the most serious problem area of fabric filter operations. Committee TC-1 (Particulates) of the Air Pollution Control Association recently surveyed baghouse installations in'the United States for the purpose of gathering information on operation and maintenance procedures and problems. One hundred thirty-three questionnaires were completed and returned. In this paper, the results of a comprehensive analysis of these data are described and interpreted. A multiple-choice type of compilation of the responses has been used to permit statistical interpretation of the results. Due to the length of the questionnaire and the tables which resulted from the analysis, these are described but not included in the following paper. They are available from the TC-1 Committee c/o APCA.     

Factors Influencing the Emissions of Nitrated-Polynuclear Aromatic Hydrocarbons(Nitro-PAH) from Diesel Engines

The potential problem of 1-nitropyrene (1-NP) formation during filter sampling of diesel emissions from dilution tubes is assessed. Rates of formation are calculated using data generated from several independent filter exposure studies. A portion of the 1-NP (12% average) found in participates collected from light-duty (LDD) and heavy-duty diesels (HOD) was found to be due to formation on the filter under average sampling conditions of 10-15/1 dilution at 44°C with 3 ppm NO₂ for 23 min. On the average, the concentration of 1-NP in participates emitted from HDD is 16 times less than that found in LDD run under similiar transient conditions. The average emission rate of 1-NP generated from the LDD and HDD was 4.7 μg/km and 1.5 μg/km, respectively for the vehicles operating under Federal Test Procedure (FTP)-transient conditions. Under operating conditions which increase exhaust temperature (increased speed and load), the concentration of nitro-PAH is significantly reduced with a concurrent increase in the concentration of partially oxidized nitro-PAH and dinitro-PAH. The concentration of 1-NP in the particulates measured from HDD in these dilution tube studies (0.33-0.95 ppm, depending upon engine load) is comparable to that measured in highway tunnel experiments (0.54 ppm average).     

An Evaluation of the Semi-VOST Method for Determining Emissions from Hazardous Waste Incinerators

The Semi-Volatile Organic Sampling Train method was investigated to determine its reliability and to determine the bias and precision of the method when used to determine emissions from hazardous waste incinerators. Experiments showed that the matrix and sampling variables usually involved in sampling emissions from a hazardous waste incinerator had no significant effect on the recovery of 11 different organic compounds. Significant losses of the sampled compounds can occur during sample preparation. The degree of loss appears to be directly related to the compounds, vapor pressure. These losses can be corrected for by adding deuterated surrogates to the sample and analyzing the surrogates along with the native compounds.

The bias determination was based on dynamic spiking of the sampling train with five deuterated organic compounds selected from Appendix VIII of the Resource Conservation and Recovery Act regulations. The results show biases of from -1 ± 8 percent to -18 ± 27 percent for chlorinated and nonchlorinated compounds. Pyridine, a water-soluble compound, showed a larger bias of-29 ± 13 percent. Particular attention to the recovery of water soluble compounds is necessary to minimize bias in their determinations. Further work is needed to determine the reliability of laboratory-determined retention volumes that are used to determine sampling conditions.     

The Regulation of Toxic Air Pollutants A Critical Review

ABSTRACT

Passage of the 1990 Clean Air Act Amendments launched the Acid Rain Program in the United States. This initiative, based on the market mechanism of a sulfur dioxide tradable “allowance” system, was a dramatic departure from traditional command and control strategies designed to reduce air pollution emissions. Power plant managers have flexibility under the program to select and implement a variety of options to reduce emissions below mandated levels. Federal agencies have collected annual performance data for affected facilities covered by the program for a number of years. Coal-burning plants are typically greater generators of sulfur dioxide (SO₂) than oil burners of equivalent size. This study examined the effect of fuel type as a significant factor influencing a plant's achievement in reducing pollution emissions. Achievement was measured by using a derived variable, delta (A), defined as the difference between pounds of SO₂ produced divided by the energy (in million Btu) generated, for the years 1990 and 1995. Rigorous nonparametric statistical analyses were used to compare the two populations of coal-fired and oil-fired plants. Results indicated that coal-burning facilities achieved greater program success, measured by the expected value of delta, than the oil combustors for the five-year period reviewed. Since utility managers must take steps to ensure all applicable requirements of the program are met, findings of the inquiry should prove to be useful in assessing achievable emissions reductions and aid in long-range facility planning.     

Validation of Models for Predicting Formaldehyde Concentrations in Residences due to Pressed-Wood Products

This paper describes a laboratory project to assess the accuracy of emission and indoor air quality models to be used in predicting formaldehyde (HCHO) concentrations in residences due to pressed-wood products made with urea-formaldehyde bonding resins. The products tested were partlcleboard underlayment, hardwood- plywood paneling and medium-density fiberboard (mdf). The products were initially characterized in chambers by measuring their formaldehyde surface emission rates over a range of formaldehyde concentrations, air exchange rates and two combinations of temperature and relative humidity (23° C and 5 0% RH; 26°C and 60% RH). They were then installed in a two-room prototype house in three different combinations (underlayment flooring only; underlayment flooring and paneling; and underlayment flooring, paneling, and mdf). The equilibrium formaldehyde concentrations were monitored as a function of air exchange rate. Particleboard underlayment and mdf, but not paneling, behaved as the emission model predicted over a large concentration range, under both sets of temperature and relative humidity. Good agreement was also obtained between measured formaldehyde concentrations and those predicted by a mass-balance indoor air quality model.     

Determination of Room Temperature OH Rate Constants for Acetylene,Ethylene Dichloride,Ethylene Dibromide,p-Dichlorobenzene and Carbon Disulfide

A relative rate procedure was used to measure hydroxyl rate constants at room temperature in the presence of oxygen. The photolysis of methyl nitrite in the presence of nitric oxide was used to generate OH radicals. The rate of loss of the test compounds was measured relative to that of ethane (k_OH = 2.74 × 10^-13 cm³ molec^-1 s^-1). The rates obtained at 297 ± 2 K are: acetylene = (7.8 ± 1.6) × 10^-13 cm³ molec^-1 s^-1,1,2-dichloroethane (2.8 ± Q.6) × 10^-13 cm³ molec^-1 s^-1, 1,2-dibromoethane (2.4 ± 0.5) × 10^-13 cm³ molec^-1 s^-1, p-dichlorobenzene (4.3 ± 0.9) × 10^-13 cm³ molec^-1 s^-1 and carbon disulfide (29 ± 6) × 10^-13 cm³ molec^-1 s^-1. Under a proposed EPA rule, this OH rate determination procedure could be used to determine if a given volatile organic will be subject to control for reduction of photochemical ozone.     

Precision and Accuracy in the Determination of Sulfur Oxides,Fluoride, and Spherical Aluminosilicate Fly Ash Particles in Project MOHAVE

The precision and accuracy of the determination of particu-late sulfate and fluoride, and gas phase SO₂ and HF are estimated from the results obtained from collocated replicate samples and from collocated comparison samples for high-and low-volume filter pack and annular diffusion denuder samplers. The results of replicate analysis of collocated samples and replicate analyses of a given sample for the determination of spherical aluminosilicate fly ash particles have also been compared. Each of these species is being used in the chemical mass balance source apportionment of sulfur oxides in the Grand Canyon region as part of Project MOHAVE, and the precision and accuracy analyses given in this paper provide input to that analysis. The precision of the various measurements reported here is ±1.8 nmol/m³ and ±2.5 nmol/m³ for the determination of SO₂ and sulfate, respectively, with an annular denuder. The precision is ±0.5 nmol/m³ and ±2.0 nmol/m³ for the determination of the same species with a high-volume or low-volume filter pack. The precision for the determination of the sum of HF(g) and fine particulate fluoride is ±0.3 nmol/m³. The precision for the determination of aluminosilicate fly ash particles is ±100 particles/m³. At high concentrations of the various species, reproducibility of the various measurements is ±10% to ±14% of the measured concentration. The concentrations of sulfate determined using filter pack samplers are frequently higher than those determined using diffusion denuder sampling systems. The magnitude of the difference (e.g., 2-10 nmol sulfate/m³) is small, but important relative to the precision of the data and the concentrations of particulate sul-fate present (typically 5-20 nmol sulfate/m³). The concentrations of SO₂(g) determined using a high-volume cascade impactor filter pack sampler are correspondingly lower than those obtained with diffusion denuder samplers. The concentrations of SO_x (SO₂(g) plus particulate sulfate) determined using the two samplers during Project MOHAVE at the Spirit Mountain, NV, and Hopi Point, AZ, sampling sites were in agreement. However, for samples collected at Painted Desert, AZ, and Meadview, AZ, the concentrations of SO_x and SO₂(g) determined with a high-volume cascade impactor filter pack sampler were frequently lower than those determined using a diffusion denuder sampling system. These two sites had very low ambient relative humidity, an average of 25%. Possible causes of observed differences in the SO₂(g) and sulfate results obtained from different types of samplers are given.