BOP Air Cleaning Experiences

The basic oxygen process of steel manufacture evolves a large volume of gas at high temperature during the oxygen blow. This gas contains finely divided oxide particles that are removed in gas-cleaning equipment. Either electrostatic precipitators or water scrubbers are commonly used for the purpose. These devices are quite efficient but breakdowns, usually in the auxiliary equipment, are frequent. Maintenance problems arise primarily from the high temperature of the gases which warps and cracks the plates in the hood that draws the gases to the cleaning device, and from erosion of piping caused by abrasive particles moving at high velocity. This paper presents a number of case histories of BOP gas-cleaning installations, details maintenance problems, and discusses corrective measures that have been adopted. It gives reasons why merely appropriating a large sum of money for cleaning devices does not always guarantee full abatement of air pollution from the basic oxygen process.     

Air Pollution Equipment for Foundry Cupolas

The choice of air pollution equipment best suited for a specific foundry cupola involves the consideration of a number of factors.—They are: (1) The design of the cupola, including openings, door enclosures, height of stack, etc. These features greatly affect the size, cost, and efficiency of control systems. (2) The constituents of the effluent gas and the other properties, such as temperature and volume, are extremely important because corrosion, warpage, and low efficiency can result from these variables. (3) Four distinctly different types of air pollution control equipment are available for cupolas. They vary widely in initial cost, operating cost, and maintenance, but also vary widely in efficiency. (4) Local air pollution regulations and community considerations dictate the choice of air pollution equipment. Those regulations now in force are quite stringent in some localities, but quite lenient in others. An incremental approach to installation of systems would make one economically feasible for the small foundry.     

Air Pollution Control Costs for Coal-to-Electricity Systems

This paper describes a comprehensive set of economic models developed to assess the air pollution control costs of alternative systems for generating electricity from coal. Models of individual system components were formulated based on engineering and statistical analyses of other detailed models and data reported in the literature for currently available technologies. The air pollution control options modeled include 4 levels of physical coal cleaning, 3 types of dry fly ash collectors, a wet limestone FGD system, and 2 options for solid waste disposal. In addition, the cost of a power plant with no air pollution controls was modeled to determine the total system cost, including energy needed to operate environmental control systems. The principal criteria guiding the development of these models were that they be (1) computationally simple and economical to use, with a minimum of detailed data requirements, (2) sensitive to variations in pollutant emission regulations, coal characteristics, and key plant design parameters, and (3) systematic, based on a specified amount of power production and the same constant dollars. Extensive sensitivity analyses and case studies performed with these models indicate excellent agreement with the results of other studies and models applicable only to individual environmental control options. Applications of these models are discussed and illustrative results presented.     

Energy Consumption Requirements for Air Pollution Control Equipment at An Iron Foundry

Energy consumption requirements for air pollution control equipment were studied for varying removal efficiency levels at the Tyler Pipe Industries iron foundry in Tyler, Texas, based on plant fuel consumption data, and on field test measurements of cupola carbon monoxide and particulate control equipment. Natural gas consumption for CO removal increased from 0 in 1970 to 25.4% of the plant total in 1976. Operating costs to achieve 85% CO control increased from 0 in 1970 to $1.61/ton metal in 1976. Increasing cupola incinerator temperature from 800° to 1600° F increased CO removal efficiency from 60 to 97%, but also increased natural gas consumption by 150%. Electricity consumption requirements for 95% to 97% particulate control at the foundry increased from 0.1 % of plant total in 1970 to 18.7% in 1976. Electricity consumption for particulate controls increased plant operating costs from 0.004 in 1970 to 1.693 $/ton metal in 1976 as horsepower increased from 20 to 6,272. Cost-benefit methodology is needed to evaluate trade-offs between air pollution control, energy consumption requirements and operating costs of proposed regulations. Total air pollution control system must be considered in enforcing regulations instead of the source to be controlled alone for overall impacts. Need exists for process modifications to enhance energy recovery and development of energy-effective air pollution control equipment.     

Some Applications of Microscopy to Air Pollution

The microscope as it has been and is now applied to air pollution work is discussed. A summary of the most common particulate sampling equipment is presented and distinctions as to the area of usage (suspended, or settled particulates) are made in each instance. Actual cases are discussed in which the polarizing microscope was used to determine identities and source of particulate pollutants. Particles from such sources as power plants, feed mills, and combustion sources are discussed and photomicrographs of known samples and unknown particles causing complaints are presented and compared as part of the discussion. References are given which deal with sampling equipment and microscopic analysis of various particulates.     

A High Volume Stack Sampler

This paper deals with the development design, and trial application of a sampling train to gather a relatively large amount of particulate sample in a short period of time. With air pollution sources installing control equipment to reduce emissions to the required low levels, it becomes necessary to use a sampling device which can collect a representative sample in a reasonable period of time. Some of the sampling trains currently being specified are expensive, awkward, and nearly impossible to use under field conditions. The high-volume train overcomes ail of these shortcomings and has some additional advantages. It uses the same glass fiber filter that is specified for ambient air particulate sampling so the emission test results are directly comparable to ambient air sampling data. The laboratories currently weighing and analyzing the glass filters need no additional equipment for the emission sampling analysis. The sample collected by the high-volume probe may be analyzed microscopically for size and characteristics of the particles. This is very important if control equipment is to be specified for the process or source. The high-volume sampler was evaluated on field tests of wood fired boilers, incinerators, wigwam burners, asphalt batching plants, seed cleaning plants, and wood fiber filtration systems. The results of several typical tests using the sampler on these sources are included in the paper.     

Epidemiological Aspects of Air Pollution

An urban air pollution incident, like a natural or man-made catastrophe, presents a crisis situation which can only be relieved if adequate contingency plans have been prepared in advance and an effective control organization is in a state of operational readiness to meet the threatened emergency. Although many air pollution incident control plans have been proposed in the past, most have remained in the conceptual or theoretical stages of preparation, because the relative infrequency of serious urban air pollution crises and the disruptive nature of major emission control operations tend to limit the opportunities available for field testing of these plans. In this respect, air pollution incident control planning is analogous to strategic planning for a military operation, where the only completely legitimate test of a strategy is applied on the battlefield. In order to accomplish the transition from conceptual planning to a practical, operational field strategy for air pollution incident control, a program of incident control tests has been initiated in Chicago. These field tests, which use the city as a laboratory for the development of control strategies, are analogous to a series of military war games in which communication systems, command and control organizational structures, personnel roles, surveillance and monitoring equipment, control resources and pollution source controllability are tested under conditions which approximate as closely as possible the situation which prevails during an actual air pollution incident. This paper discusses the evolution of an incident control strategy from an initial, fixed response emission control exercise, through a meteorologically initiated control test to a fairly realistic war game series which is still developing.     

Costs of Air Cleaning with Electrostatic Precipitators at TVA Steam Plants

Cost data were analyzed from thirty steam power plant units utilizing electrostatic precipitators with or without mechanical centrifugal collectors. Operational, maintenance, and total costs for the years 1969, 1970, and 1971 were expressed in 1972 dollars as $/cfm-yr and $/^cf^m-yr-efficiency. The latter parameter is a new one which normalizes the cost of air cleaning by accounting for the amount of particulate matter collected. Large differences in the costs of air cleaning were found between plants and even between units operating in the same plant. Maintenance costs appeared to be the main contributor to large total cost differences, but improved, more specific accounting procedures are required to focus more closely on the reasons for cost differences.     

Capital and Operating Costs of Selected Air Pollution Control Systems — I

This is the first installment of a 4-part series which will present capital and operating costs of selected air pollution control systems. The objective of the Series is to identify the individual component costs so that realistic system cost estimates can be determined for any specific application. In Part I, cost estimating procedures and curves are provided to develop the equipment costs for electrostatic pre-cipitators, venturi scrubbers, fabric filters, incinerators, and adsorbers.     

The Air Pollution Control Contractorand SMACNA

Over the years JAPCA has directed its attention primarily to the scientist and engineer in their roles as industrial air quality managers, consultants, control officials, educators, researchers, and manufacturers of emission control equipment and air pollution instrumentation. Largely overlooked has been the air pollution control contractor who evolved from the sheet metal industry to become a key figure in the environmental marketplace. Let's look "beyond the flange", as it were, at this contractor, his work, his association, and the professional development opportunities being offered to him.     

Problems of Meeting Multiple Air Quality Objectives for Coal-Fired Utility Boilers

Gaseous wastes and particulate emissions are produced in the process of burning coal to produce electrical energy. In attempting to control these gaseous wastes, changes in the operation efficiency of boilers and secondary equipment are likely to result, and in addition liquid and solid waste streams are produced. The interrelationships among the various forms of wastes and the effects of air quality control on process efficiency are often overlooked in studies of environmental quality management.

The study was undertaken to evaluate the technical alternatives for handling gaseous and particulate emissions from coal-fired boilers and to determine the feasibility of meeting several standards simultaneously. The gaseous emissions of major importance in the combustion of coal are parti culates, oxides of sulfur, and oxides of nitrogen. Particulates can be controlled by a tradeoff among further preparation at the mine (for additional ash removal), type of boiler, use of dust control equipment and high stacks for dispersion of residual emissions, if ambient air standards are considered. Oxides of sulfur reduction depends currently on fuel substitution, limestone additives in the boiler and some form of contact process such as wet scrubbing, or the use of high stacks. Oxides of nitrogen control in coal fired boilers is restricted to small reductions by either changes in boiler operation, such as lower excess air levels, adsorption during wet scrubbing or by dispersion from high stacks.     

Effectiveness of Photocatalytic Filter for Removing Volatile Organic Compounds in the Heating,Ventilation, and Air Conditioning System

Abstract

Nowadays, the heating, ventilation, and air conditioning (HVAC) system has been an important facility for maintaining indoor air quality. However, the primary function of typical HVAC systems is to control the temperature and humidity of the supply air. Most indoor air pollutants, such as volatile organic compounds (VOCs), cannot be removed by typical HVAC systems. Thus, some air handling units for removing VOCs should be added in typical HVAC systems. Among all of the air cleaning techniques used to remove indoor VOCs, photocatalytic oxidation is an attractive alternative technique for indoor air purification and deodorization. The objective of this research is to investigate the VOC removal efficiency of the photocatalytic filter in a HVAC system. Toluene and formaldehyde were chosen as the target pollutants. The experiments were conducted in a stainless steel chamber equipped with a simplified HVAC system. A mechanical filter coated with Degussa P25 titania photocatalyst and two commercial photocatalytic filters were used as the photo-catalytic filters in this simplified HVAC system. The total air change rates were controlled at 0.5, 0.75, 1, 1.25, and 1.5 hr^?1, and the relative humidity (RH) was controlled at 30%, 50%, and 70%. The ultraviolet lamp used was a 4-W, ultraviolet-C (central wavelength at 254 nm) strip light bulb. The first-order decay constant of toluene and form-aldehyde found in this study ranged from 0.381 to 1.01 hr^?1 under different total air change rates, from 0.34 to 0.433 hr^?1 under different RH, and from 0.381 to 0.433 hr^?1 for different photocatalytic filters.     

Net Waste Reduction Analysis Applied to Air Pollution Control Technologies

Post-combustion air pollution control technologies were evaluated to determine total waste produced by the operation of these systems. A continuum of air pollution control technology choices providing increasing levels of control is presented and the quantity of waste produced by each air pollution control option has been calculated. In addition, this analysis accounts for waste produced indirectly by the generation of energy required for operation of the control technologies. This type of analysis can be used to select optimal control levels and to demonstrate why a goal of zero air emissions may not be environmentally desirable.     

Pennsylvania’s Compuiterized Air Monitoring System

The Pennsylvania Air Pollution Commission has developed a regulatory program based upon the control of local air pollution problems and reduction of pollutant levels in air basins. The geographical boundaries of 10 air basins have been established. The Commission’s air basin regulations will provide for the reduction of over-all pollutant levels and for emergency procedures in the event of adverse meteorological conditions. The paper discusses the format and objectives of the program.

In order to effectively enforce the air basin regulations and maintain the necessary surveillance of the state’s air quality, a "computerized real time on-line integrated air monitoring-data handling system" has been designed. The system will incorporate a network to constantly monitor the air in each air basin.The primary objectives of the system are: 1. Constant surveillance of air pollution in the air basins.

2. Provide information on air pollution potential alerts.

3. Aid in further development of air quality criteria and regulations.

The air monitoring network is estimated to include approximately 25 remote stations. Each remote will contain air pollution and meteorological sampling equipment and hardware to telemeter to a central station. The data will be transmitted over leased telephone lines. The central station in Harrisburg will contain the necessary hardware to receive and process data, calculate and display results and permit supervisory control of the network. Output options will include immediate display of edited data, command and alarm information, and presentation of statistical results.

Although the air monitoring system is one of the principle ingredients of the program, the air basin concept encompasses other component systems designed to knit together the entire air pollution control program in Pennsylvania.     

Government/Industry Cost Sharing for Air Pollution Control

Several existing federal and state provisions act to reduce the cost to in dustry of controlling air pollution. Included are the federal corporate income tax, depreciation allowances, investment credits, small Business Administration loans, Economic Development Administration aid, and state tax laws. These provisions give government assistance to industry amounting to as much as 59 percent of the cost of air pollution control. Numerous bills have been introduced in Congress that would give additional government aid to industry in the form of special across-the-board tax allowances for air pollution control equipment. A typical bill of this type would result in the government bearing an additional 11 percent of these costs. There are several possible objectives for this kind of additional aid; however, none of these seem valid when the amount of present assistance is recognized. From this analysis, it would seem that additional across-the-board tax subsidies for air pollution control equipment are neither required nor advisable. Future studies and/or experience may show certain firms or industries for which air pollution control will be too great a burden and for which additional government assistance is advisable. When such cases are found, legislation should be enacted only after the pros and cons of the various assistance methods are considered.     

Mobile Air Quality Monitoring Systems: Present Problems and Future Needs

This overview represents much of the discussion and summarizes many of the concerns emerging from the recent APCA Specialty Conference, “In-Situ Air Quality Monitoring from Moving Platforms.”

Users of mobile air quality monitoring systems have been hampered in their attempts to generate dependable data because of a lack of suitable instrumentation. Most equipment used in mobile systems was designed for laboratory or stationary monitoring applications and cannot cope well with the harsh environment encountered in aircraft or other mobile platforms. Only through innovative modifications have investigators been able to utilize off-the-shelf equipment. The technology exists, however, for manufacturers to build a much higher quality product if only a market incentive could be created.

This paper outlines problem areas which need to be addressed in the production of reliable “mobile quality” instrumentation, and suggests some market incentives.     

Economic comparison of emission control systems for glass manufacturing furnaces with heat recovery

Glass manufacturing, like other process industries, is faced with air pollution compliance problems due to ever stricter emission limits. Several waste gas cleaning equipment options are available for air pollution control (APC) in glass plants, the most common arrangements being based on electrostatic precipitator (ESP) or fabric filter (FF) dust collectors and semi-wet or dry processes for acid gas removal. However, several counteracting aspects affect the choice of gas cleaning technologies, which are confirmed by the discrepancies encountered in actual suppliers' bids. In this paper, the main pollution control options are analyzed by carrying out a critical comparison under the cost-effectiveness point of view to select the lowest cost arrangement considering capital investment, operating expenses, and energy-saving revenues from heat recovery processes. The analysis is carried out with reference to a case study involving actual float glass production lines at Pilkington plants in Italy.     

Elimination of VOC Emissions from Surface Coating Operations

Collectively, surface coating operations using paints with hydrocarbon solvents may well be the largest industrial source of volatile organic compounds (VOC) and hazardous air pollutants (HAP). Most surface coating operations involve the manual application of paint with spray equipment inside a paint spray booth. The booth exhaust system collects the solvent fumes and then exhausts them through a stack to the atmosphere. Stack emissions are characteristically high in flow rate and low in concentration. Since control equipment is sized based on exhaust flow rate rather than concentration, control of VOC and HAP requires large, expansive abatement equipment. Simple, effective designs employing recycling of air have greatly reduced the exhaust flow rate and the cost of the control equipment. However, these designs are not popular because they are burdened by various flaws, notably worker endangerment. The Mobile Zone recirculation system can be incorporated into new construction or retrofitted to existing spray booths and will reduce the exhaust volumes ranging from 65 to 95 percent without adversely affecting the production rate, production quality or worker safety.     

Smokeless Stacks—Industry’s Big Problem

There seems to be a general impression on the part of the public and many technical people that dust collecting systems on the open hearth furnace are simply a matter of giving a contract for a duplicate system to that previously installed; signing a check for a sum to cover the cost of the cleaning equipment itself, pressing the start-up button and then sitting back to receive the plaudits of a grateful community. This paper will briefly present some of the problems common to all of the installations to date. It will also explain why the cost of the cleaning equipment itself is such a small portion of the total cost.     

Design of Adsorption Equipment in Air Pollution Control

The purpose of this paper is to provide a helpful tool for the design of adsorption equipment, recognizing in particular the recent, more stringent regulations on air pollution. This work is based on an earlier paper by Hougen and Marshall,¹ who developed therein an analytical adsorption model. Under certain assumptions, especially that of linear adsorption equilibrium, it is possible to express the results in the form of convenient usable charts. Although more sophisticated models² have recently been developed, the numerical effort involved in solving the associated partial differential equations is such that practical application is often questionable.