Electrostatic Precipitator Maintenance Survey

In the latter part of 1974, the TC-1 Committee of the APCA undertook a survey of four (4) major user industries of electrostatic pre-cipitators. The purpose of the survey was to establish the users’ degree of satisfaction with this equipment from an operational and a maintenance viewpoint. Specific areas of maintenance requirements were investigated as well as the nature of difficulty experienced. The 174 responses received covered user experience with 243 precipi-tators of various manufacturers. This paper reports on the results of this survey and gives the statistics derived. The conclusions reached should be beneficial to the user and the manufacturer in the areas of product improvement and maintenance.

This is the first of this type of survey handled by the TC-1 Committee, and it will be followed by Fabric Filter and Scrubber information gathering questionnaires. Problem areas so defined will be enlarged upon in future seminars planned under APCA auspices.     

PM Fine Standards and Implied Modeling/Analysis Needs

ABSTRACT

New National Ambient Air Quality Standards (NAAQS) were promulgated for fine particulate matter (FPM) in July 1997. This paper summarizes likely timing for implementing programs to meet these standards, which have a bearing on future modeling/analysis needs. The paper notes technical requirements implied by the nature of the NAAQS, as well as feedback the agency has received concerning modeling/analysis through Federal Advisory Committee Act (FACA) subcommittee work groups. Conclusions and recommendations drawn from recently completed U.S. Environmental Protection Agency (EPA)- sponsored workshops on modeling and other source attribution techniques are also described. Efforts to respond to needs implied by the NAAQS and feedback are noted by outlining major topics and issues that future guidance on use of modeling and other analyses used for attainment demonstrations will need to address. The paper concludes by highlighting several as yet unmet modeling/analysis needs to support a well-founded strategy for meeting air quality goals for FPM. These are suggested as potential areas for policy-relevant research.     

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

Electric utilities have made significant progress in recent years in designing and operating baghouses for collection of coal fly ash. As a result, early concerns with high operating and maintenance requirements and short bag lives are no longer an issue. With increasingly stringent air emissions regulations and imminent revision of the Clean Air Act, baghouses have become an attractive particulate collection option for utilities.

In order to keep its member utilities apprised of the latest design and operation and maintenance experience with baghouses, the Electric Power Research Institute has been conducting surveys of utility baghouse user experience. This paper presents results from the latest survey, conducted in 1989. A previous survey was conducted in 1985. The 1989 survey was conducted using questionnaires mailed to the utilities, telephone inquiries, and plant visits. This paper discusses the general trends observed in baghouse design, performance, operation and maintenance.     

The Importance of Maintenance for Lime Flue Gas Desulfurization Systems

The successful, reliable operation of a power plant flue gas desulfurization (FGD) system depends largely on a good program of maintenance. Identifying the FGD equipment that is most critical to an FGD system’s overall reliability or its ability to meet emission regulations plays an important role in determining the extent of a maintenance program for a particular site. FGD maintenance programs vary considerably, depending on site-specific requirements and the support of plant owners. Many owners are reluctant to spend money on FGD maintenance because an FGD system is a nonproductive part of a power plant; however, a good maintenance program can result in longer equipment life, improved equipment performance, increased system availability, better safety, and lower operating costs. This paper uses wet and dry lime FGD systems to illustrate the advantages of good maintenance and the consequences of poor maintenance. Examples of specific tasks for preventive, scheduled, planned, and emergency maintenance are described. Also, because of the importance of FGD maintenance personnel, a section on organization and training is included.     

Performance Characteristics of Instrumental Methods for Monitoring Sulfur Dioxide

The performance characteristics of commercially available sulfur dioxide monitors were determined. Con-ductimetric, colorimetric, and coulometric analyzers were investigated. During this phase of the study, characteristics that were more closely related to field operation were studied. These included comparability of data among the instruments over a period of time, weekly calibration drift, maintenance requirements (including operating cost), unattended operation performance, and the effect of rotameter changes on calibration. The methodology and apparatus used to determine each operational parameter are described. The results of this study should be useful in the selection of instruments for monitoring sulfur dioxide.     

A History of Dry Cleaners and Sources of Solvent Releases from Dry Cleaning Equipment

Approximately 25, 000–35, 000 dry cleaning facilities currently operate in the U.S. The release of perchloroethylene and other solvents from these establishments represents a major source of soil and groundwater contamination. The manner in which dry cleaning solvents escape from dry cleaning plants is, for all practical purposes, identical for chlorinated and petroleum hydrocarbon solvents and is related to one of the following events: the catastrophic failure of a component of the dry cleaning system, the improper installation, operation or maintenance of the dry cleaning equipment or a combination of all of these causes. Acceptable customs, codes and regulations can also dictate what is authorized for operation of a dry cleaning facility in a particular community, geographic area during a particular time frame. Environmental litigation dealing with the origin of a solvent release from dry cleaners tends to focus on the design and manufacture of dry cleaning industry machines such as washers, washer extractors, tumblers, solvent filters, water separators, stills and spotting boards. A thorough analysis of the daily operations of dry cleaners often reveals that poor maintenance, failure to follow the manufacturer's instructions and the actions of the operator are the most likely causes of soil and groundwater pollution. In order to forensically evaluate the most probable origins of a solvent release and to examine issues regarding liability, a thorough understanding of the history of dry cleaning and a detailed analysis of the operation and maintenance of the dry cleaning equipment are necessary. The discovery of solvent plumes in the vicinity of dry cleaning plants may suggest that the solvent source is the dry cleaning plant; however, the presence of these plumes does not necessarily indicate that the dry cleaning equipment was defectively designed or manufactured. A thorough review of the type of equipment used over the life of the dry cleaning plant and verifiable solvent mileage records frequently indicates that operators of the plant have disposed of solvent and contaminated solids into the municipal sewer or on ground surfaces.     

A History of Dry Cleaners and Sources of Solvent Releases from Dry Cleaning Equipment

Approximately 25, 000-35, 000 dry cleaning facilities currently operate in the U.S. The release of perchloroethylene and other solvents from these establishments represents a major source of soil and groundwater contamination. The manner in which dry cleaning solvents escape from dry cleaning plants is, for all practical purposes, identical for chlorinated and petroleum hydrocarbon solvents and is related to one of the following events: the catastrophic failure of a component of the dry cleaning system, the improper installation, operation or maintenance of the dry cleaning equipment or a combination of all of these causes. Acceptable customs, codes and regulations can also dictate what is authorized for operation of a dry cleaning facility in a particular community, geographic area during a particular time frame. Environmental litigation dealing with the origin of a solvent release from dry cleaners tends to focus on the design and manufacture of dry cleaning industry machines such as washers, washer extractors, tumblers, solvent filters, water separators, stills and spotting boards. A thorough analysis of the daily operations of dry cleaners often reveals that poor maintenance, failure to follow the manufacturer's instructions and the actions of the operator are the most likely causes of soil and groundwater pollution. In order to forensically evaluate the most probable origins of a solvent release and to examine issues regarding liability, a thorough understanding of the history of dry cleaning and a detailed analysis of the operation and maintenance of the dry cleaning equipment are necessary. The discovery of solvent plumes in the vicinity of dry cleaning plants may suggest that the solvent source is the dry cleaning plant; however, the presence of these plumes does not necessarily indicate that the dry cleaning equipment was defectively designed or manufactured. A thorough review of the type of equipment used over the life of the dry cleaning plant and verifiable solvent mileage records frequently indicates that operators of the plant have disposed of solvent and contaminated solids into the municipal sewer or on ground surfaces.     

Single-Stage Dewatering of FGD Waste

The Escalante Unit No. 1 flue gas desulfurization (FGD) waste slurry dewatering system represents the first domestic utility to deviate from the typical industry two-stage dewatering system design. Evaluations conducted during the design phase compared three dewatering options: 1) thickener in series with vacuum filters, 2) thickener in series with centrifuges, and 3) centrifuges with no thickener. The evaluation showed that centrifuges with no thickener (one stage) could significantly reduce capital costs. Coupled with capital costs, this option also decreases operation and maintenance costs, reduces the complexity of the system, saves a considerable amount of space, and centralizes the FGD and dewatering systems within one building. This paper describes the evaluation that took place during the design phase of the project comparing the three dewatering options. Operational data for the first year of operation are presented, and operating and maintenance costs are discussed and compared with conventional two-stage dewatering systems.     

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.     

Solving Problems in the Electrical Energization of Electrostatic Precipitators

Achieving and maintaining continuous, reliable performance in electrostatic precipitators depends critically upon the proper design, application, operation, and maintenance of the high voltage electrical energization system. Common problems among these factors are discussed, and effects on performance are illustrated from field experience. Practical recommendations for solving problems and for preventing their occurrence in the electrical aspects of precipitation are presented for effective use by designers, operators, and maintenance personnel.     

Inspection and Maintenance for Reducing Automobile Emissions

EPA has recently evaluated several inspection and maintenance approaches for in-use vehicles that are potentially applicable to pre-1975 automobiles. The results of this evaluation are described and used to estimate the effecliveness and cost of inspection/maintenance for reducing total automobile emissions through 1985. It is estimated that inspection/maintenance programs for pre-1975 automobiles may be capable of achieving eight and ten percent reductions in total automobile emissions of HC and CO respectively until 1980 and two to three percent reductions in 1985. The need for inspection of automobiles of model year 1975 and later, and the potential applicability of present short-duration inspection procedures to these vehicles, are also discussed.     

Control of Atmospheric Emissions From Petroleum Storage Tanks

Informative Report No. 2, prepared by the TI-3 Petroleum Committee of the Air Pollution Control Association, deals with the control of hydrocarbon vapor emissions from petroleum storage tanks. The report presents the theory of evaporation loss from liquids, describes emission control equipment and its maintenance, and outlines techniques used to estimate the magnitude of and to reduce emissions.     

A Portable Electrical Analyzer for Size Distribution Measurement of Submicron Aerosols

An electrical aerosol analyzer capable of performing rapid, in situ size distribution measurement on aerosols from 0.003 to 1 μm diameter has been described. The instrument is based on the “diffusion charging-mobility analysis” principle first described by Whitby and Clark. The prototype instrument has a total volume of 3.75 ft³ and a total weight of 60 lb, and is sufficiently portable to be used on small airplanes and ground based vehicles for mobile air pollution studies. The paper describes the design, operation, and performance of the instrument. Sample data are presented showing the size distributions of aerosols measured by the instrument on board a small research aircraft over the Los Angeles basin at several different altitudes. In addition, data are presented showing the size distribution of smog chamber aerosols and aerosols produced by a conventional Collison atomizer.     

Concentration of Atmospheric Pollutants in the Gaseous Emissions of Medical Waste Incinerators

ABSTRACT

The purpose of this paper is to quantify the production of medical waste from a general hospital and to evaluate the atmospheric pollutant concentrations in gaseous emissions associated with its incineration. A 3.8 kg (bed.day)^-1 production of medical waste was estimated for 1998; its incineration is related with an ash production of 0.3-0.4 kg (bed.day)^-1. The concentrations of atmospheric pollutants were estimated using emission factors, comparing the effluents with and without control of atmospheric pollutants. The calculated concentrations were compared with the emission limits established by Portuguese legislation. The results indicate that, if there is no control of atmospheric pollutants, their concentrations exceed the established limits. This is observed even if correct operation and maintenance procedures are used. The emission concentrations of dioxins are higher than the Portuguese emission limit, which is particularly worrying due to the high toxicity of some of these compounds. Generally, it is possible to reduce pollutant concentrations if appropriate control equipment is used. The conclusions obtained clearly justify the great concern regarding air pollution associated with medical waste incinerators currently operating in Portugal.     

An Integrated Program to Achieve Maximum Performance of Electrostatic Precipitators

The objective of this paper is to describe the Tennessee Valley Authority's efforts and plans in designing an operating and maintenance program that will ensure maximum performance of the electrostatic precipitators at our power generating stations. Detailed operating and maintenance manuals are being prepared for each plant for the use of plant personnel. These manuals include instructions on operation, maintenance, and testing of the precipitators. Instructions on internal and external equipment inspections to be performed during unit operation, emergency and scheduled outages, and problem diagnostic procedures are included to help the plant personnel solve problem areas. Performance curves are included in the manuals which show the effect of gas volume flow, gas temperature, gas resistivity, coal changes, and loss of transformer-rectifier sets on the precipitator performance. In addition, opacity monitors that record continuous opacity readings are being installed at all our plants to assist the plant in monitoring precipitator performance. Full-time operating and maintenance crews are being organized at the plants to monitor and maintain the precipitator and ash-removal systems. Also, a staff of technical personnel is being organized at the central office to provide technical advice and assistance in design, operation, and maintenance problems and liaison and coordination for all the plants concerning the precipitators. Periodic precipitator field inspections, performance and operating parameter optimization testing, and review of the equipment operating logs are made by the central office technical personnel. Recommendations and technical assistance are then furnished to the plant with regard to the precipitator overall performance and operating characteristics.     

Transient analysis of volatile organic compound concentrations for estimating emission rates

While emission rates of volatile organic compounds (VOCs) have been obtained for building materials, furnishings and processes in chambers, field measurements are more difficult. Procedures to estimate emission rates using transient analysis of VOC concentrations are described and applied in a two-story classroom/office building. The analysis employs semi-real-time VOC concentrations determined with a portable GC/FID and simultaneous air change rate measurements using tracer gas decay. The results of the analysis yield consistent values of emission rates for building materials ranging from 0.20 to 0.40 mg m⁻² h⁻¹ when normalized by floor area. Occupancy-related emissions were more difficult to estimate and covered a wider range from roughly 0.1 to 1.5 mg m⁻² h⁻¹. The test data were also analyzed in an attempt to determine sink parameters, but these efforts were not particularly successful. Furthermore, in these tests, the inclusion of sink effects did not significantly impact the estimated emission rates. While this paper offers a transient analysis approach that may lead to improved field estimates of VOC emission rates, it is not presented as a definitive methodology. Nevertheless, transient analysis has potential for use in other buildings, but simultaneous air change rate measurements are critical in its application in estimating VOC emission rates in the field.     

A feasibility study on the predictive emission monitoring system applied to the Hsinta power plant of Taiwan Power Company

The continuous emission monitoring system (CEMS) can monitor flue gas emissions continuously and instantaneously. However, it has the disadvantages of enormous cost, easily producing errors in sampling periods of bad weather, lagging response in variable ambient environments, and missing data in daily zero and span tests and maintenance. The concept of a predictive emission monitoring system (PEMS) is to use the operating parameters of combustion equipment through thermodynamic or statistical methods to construct a mathematic model that can predict emissions by a computer program. The goal of this study is to set up a PEMS in a gas-fired combined cycle power generation unit at the Hsinta station of Taiwan Power Co. The emissions to be monitored include nitrogen oxides (NOx) and oxygen (O2) in flue gas. The major variables of the predictive model were determined based on the combustion theory. The data of these variables then were analyzed to establish a regression model. From the regression results, the influences of these variables are discussed and the predicted values are compared with the CEMS data for accuracy. In addition, according to the cost information, the capital and operation and maintenance costs for a PEMS can be much lower than those for a CEMS.     

How big is big? How often is often? Characterizing Texas petroleum refining upset air emissions

This work examines the magnitude and frequency of Texas petroleum refineries upset air emissions over a 44-month period. Upset emissions occur during plant start-ups, shut-downs, maintenance, malfunctions and flaring incidents, and these emissions are typically exempt from regulation. These emissions contain a variety of chemicals, including benzene, nitrogen oxides, sulfur dioxide, and butadiene. Unlike other states, Texas has detailed reporting requirements, regulations in place, and an extensive upset emissions database. A key scientific and public policy question is whether upset emissions have significant impacts on local air quality and public health. However, it is not possible to address this question without first understanding the magnitude and properties of upsets. We merge related databases to examine over 3,900 upset emission events and find that upset emissions are significant in both size and occurrence when compared to routine operation emissions. It is determined that these events are not random, being more likely to occur during the summer, in the morning, and early in the workweek. A regional analysis of Port Arthur suggests that upset emissions from co-located refineries are equivalent to having an additional refinery within the region. Because of uncertainties within the reporting process and an obvious underestimation by some refineries, there is a need for better tracking of upset emissions.     

利用人工湿地脱除废水中氨氮和磷的统计分析

论述了利用人工湿地脱除废水中氨氮和正磷酸盐类污染物的统计分析,调查基于国外文献报道的研究数据和实际运行数据.结果表明,污染物输入和输出浓度关系可以由线形规律获得关联,这些污染物因子脱除动力学也可以用适于BOD降解的Kichuth一级脱除方程来描述.由不同人工湿地关联的一级动力学常数具有较好的相关性.     

Quantification of variability and uncertainty in air pollutant emission inventories: method and case study for utility NOx emissions

The quality of stationary source emission factors is typically described using data quality ratings, which provide no quantification of the precision of the emission factor for an average source, nor of the variability from one source to another within a category. Variability refers to actual differences caused by differences in feedstock composition, design, maintenance, and operation. Uncertainty refers to lack of knowledge regarding the true emissions. A general methodology for the quantification of variability and uncertainty in emission factors, activity factors, and emission inventories (EIs) is described, featuring the use of bootstrap simulation and related techniques. The methodology is demonstrated via a case study for a selected example of NOx emissions from coal-fired power plants. A prototype software tool was developed to implement the methodology. The range of interunit variability in selected activity and emission factors was shown to be as much as a factor of 4, and the range of uncertainty in mean emissions is shown to depend on the interunit variability and sample size. The uncertainty in the total inventory of -16 to +19% was attributed primarily to one technology group, suggesting priorities for collecting data and improving the inventory. The implications for decision-making are discussed.