Fabric Filter Applications on Coke Oven Pushing Operations

Coke oven pushing emissions containing quantities of tars and dust require new approaches to adapt fabric filter collectors. This paper deals with the Wheelabrator/Taisei precoat filter systems being used on coke oven pushing operations. The Taisei test program and the filter installation at Tokyo Gas are discussed. The variables to be evaluated in the design of a fabric filter emission control system are examined.     

Control of Coke Oven Emissions by Use of A Closed Pipeline Charging System

The body of information presented in this paper is directed to those individuals concerned with the control of air pollution emissions which occur as a result of the operation of by-product coke plants. It describes a new process which represents a major change in the charging operation wherein preheated coal can be charged to coke ovens via a closed pipeline system thus replacing the conventional larry charging car and thereby eliminating air pollution estimated to be as much as 70% of the total emissions from coke oven operations. Coal is dried and preheated in a continuous fluidized bed process utilizing products of combustion of coke oven gas. The coal is recovered in conventional cyclone collectors and conveyed to the ovens via a new and novel pneumatic conveying system where the gas used is superheated steam. Jet energy repeatedly thrusts the coal upward and forward through the pipe, obtaining a high efficiency of transport of solids ten times that of conventional systems. Major advantages of the process demonstrated to date include (1) elimination of emissions from charging, (2) reduction of emission from pushing, (3) improved battery top working conditions, (4) increased oven productivity as much as 45%.     

Economics of Coke Oven Charging Controls

This study was undertaken to determine which of several alternative air pollution abatement systems affords the most economical solution to the control of atmospheric emissions during the charging of coal into by-product coke ovens. The study was limited to the consideration of existing by-product batteries, and the assumption was made that no coking plant has the alternative to do nothing nor will the plant choose to delay abatement through legal procedures. The data indicate that a jumper pipe installation with a new larry car provides the most economical control.     

AISI-EPA-Battelle Coke Oven Door Sealing Program

The problem of coke oven door leakage is generally recognized as one for which no proven solution exists. In 1974 the United States Environmental Protection Agency and the American Iron and Steel Institute entered into a jointly funded research project with Battelle Columbus Laboratories. The initial project was to define the problem by literature search, operator interviews and profile measurements of jambs and doors.

Numerous concepts of seal designs were developed and then rated by industry and Battelle reviews. It was determined that a metal-to-metal seal offered the greatest probability of success. It was felt that jamb warpage was the most serious problem to be solved.

In the fall of 1976 another contract was signed by EPA and AISI assigning Battelle the task of developing to the point of fabrication a system to eliminate or significantly reduce leakage from coke oven end closures. This program included mathematical modeling, physical modeling, field data collecting, analysis, and full scale unit design.

A retrofittable door seal design has been developed and preparations are underway for operating evaluation at eight steel plants. The design is retrofittable to the two principal coke oven doors in service and should accommodate the worst jamb warpage usually found.     

Economics and Alternatives for Sulfur Removal from Coke Oven Gas

Two processes are currently being employed in North America for the desulfurization of coke oven gas, the Vacuum Carbonate System, and the Stretford System. A third, the Sulfi-ban Process, which was recently announced, now has several plants scheduled for construction. Overall operating requirements for each of these processes are considered in detail. Emphasis is placed on an identification of power and steam requirements, the types and amounts of solid and/or liquid waste streams produced together with methods for their treatment, and the net desulfurization efficiencies achieved by each process. Detailed estimates of capital and operating costs for desulfurization are considered, and equipment needs for environmental control requirements are discussed.     

Performance and Problems of Claus Plant Operation on Coke Oven Acid Gases

The application of Claus Plant sulfur recovery units to the coke oven gas (COG) acid gases at three Bethlehem Steel Corporation plants is discussed. While many of the problems encountered are not unique to coke oven gas-derived acid gases, it was found that special consideration must be given to the effect of components not normally encountered in the typical Claus plant application to petroleum derived gases. It is perhaps fortunate that the feed composition to the three units was sufficiently different to expedite recognition of the source of some of these difficulties. One substance of concern is the hydrogen cyanide normally found in COG acid gases. In the absence of some means of removing or decomposing this material before it enters the Claus Plant extensive corrosion within the unit is observed after a short period of time. This is due to the fact that, contrary to expectation, a substantial quantity of this material survives the burner flame. The various alternatives in its elimination are discussed. A second major contaminant in COG acid gases is particulate iron sulfide and iron cyanide. While the exact source of these materials is in doubt, there is little doubt that in the absence of their removal, inorganic blockages within the Claus Plant will occur. By properly accounting for the special properties of coke oven gas-derived acid gas we have recently achieved short term sulfur recovery efficiencies of 95% and higher.     

An Epidemiological Study of Exposure to Coal Tar Pitch Volatiles Among Coke Oven Workers

Recent studies of mortality among coke plant workers indicate that there is an excess of respiratory cancer among men employed at the coke ovens and that the mortality is related to work areas and length of exposure to coal tar effluents, the body of information presented in this paper is directed to categorization of coke oven jobs into different work areas in terms of exposure to coal tar pitch volatiles developing an index of cumulative exposure to investigate the dose-response relationship between exposure and mortality. The exposure data have been taken from a study conducted by the Pennsylvania Department of Health, State Division of Occupational Health, and mortality data are based on a long-term study of steelworkers, conducted by the Department of Biostatistics, University of Pittsburgh. A summary index calculated for each worker combining the level of exposure and length of time exposed indicates that, as expected, both these factors are related to the development of cancer, particularly cancers of the respiratory system.

Conclusions of note are: Measured levels of coal tar pitch volatiles are 2-3 times higher for men who work at the top of coke ovens as compared to men employed at the side of the ovens. Even though the specific carcinogenic element or elements in the coke oven environment are not known at the present time, in-. creasing levels of exposure to coal tar pitch volatiles are related to art increased risk of dying from malignant neoplasms. Further coal tar pitch volatile measurements need to be made and analyses designed which will specify the dose-response relationship more precisely. This will provide information necessary to evaluate the recommended Threshold Limit Value.     

Ambient Air Quality and Automotive Emission Control

This paper is concerned with uncertainties involved in projecting ambient air quality. Ambient air quality was projected by assuming a linear dependence on estimated future emissions. Future automotive emissions were estimated by a method recommended by EPA. Projections were made for the locations reported to have the highest ambient air concentrations of each pollutant; Chicago for carbon monoxide and the California South Coast Air Basin for hydrocarbon and oxidant. The sensitivity of the projections to several input parameters was determined.

The uncertainty in projection of air quality due to the use of a maximum, once-per-year concentration is large. For example, the reduction in total CO emissions in Chicago in 1975, necessary to meet the air quality standard, was as high as 68% or as low as 26%, depending on whether the historic high, 8 hr average concentration of 44 ppm or the 1970 maximum of 21 ppm was used. The effects of uncertainties in growth rates and fraction of emissions attributed to the automobile were also sizeable. Differences in automotive growth rate had a large near-term effect on projected concentrations, while differences in nonautomotive growth rate or fraction of emissions attributed to the automobile had a large long-term effect. The effect of 1975 interim automotive emission standards on projected air quality was negligible when compared with projected air quality based on the previous Federal automotive emission standards for 1975.     

A Realistic Vehicle Emission Inspection System

A one minute mass vehicle exhaust emission inspection system is described to aid those seeking to establish an appropriate effort in compliance with the Air Quality Act of 1967. This proposed inspection system is suitable for both emission controlled and pre-emission controlled automobiles. It is oriented to appropriate Auto Service Industry corrective measures since it provides guidelines as to probable cause of unnecessarily high emissions for each rejected vehicle. This capability is essential to avoid abnormal corrective expense due to excessive repairs or continued high emissions due to inadequate repairs. Low skill levels may be used during the inspection process, yet results are repeatable and consistent in a plurality of inspection stations. The net gain in lower emissions through inspection of in-use vehicles is large because the point of rejection is no longer dictated by the inherently high emission vehicles. Not more than two rejection standards are required for emission controlled vehicles, and only one for pre-emission controlled vehicles. This includes all domestic and foreign makes. These standards are flexible in that they may be initially liberal and gradually tightened as circumstances warrant. Such policy changes or future spark ignition engine designs will not significantly obsolete the hardware required to perform this inspection. The fundamental techniques employed permit the use of greatly simplified equipment and instrumentation with resultant lower initial cost and increased reliability than previously envisioned meaningful inspection methods. A study of nearly 1000 automobiles over a one year period evolved and documented this proposed inspection system. Qualified persons may study this work to any depth desired by contacting the authors.     

Process Evaluation System Developed for the Emission Inventory

Two applications of the newly devised process evaluation criterion are described: (7) the transformation of process data concerning the air pollution sources into machine language so that it may be correlated with Chicago’s Emission Inventory; and, (2) the application of its principles to the administration of the permit system. This criterion for the evaluation of process activity is completely different from any other method used throughout the country. Examples of its application are given.     

Nitrogen Oxides Emission Control Options for Coal-Fired Electric Utility Boilers

Abstract

Recent regulations have required reductions in emissions of nitrogen oxides (NO_x) from electric utility boilers. To comply with these regulatory requirements, it is increasingly important to implement state-of-the-art NO_x control technologies on coal-fired utility boilers. This paper reviews NO_x control options for these boilers. It discusses the established commercial primary and secondary control technologies and examines what is being done to use them more effectively. Furthermore, the paper discusses recent developments in NO_x controls. The popular primary control technologies in use in the United States are low-NO_x burners and overfire air. Data reflect that average NO_x reductions for specific primary controls have ranged from 35% to 63% from 1995 emissions levels. The secondary NO_x control technologies applied on U.S. coal-fired utility boilers include reburning, selective noncatalytic reduction (SNCR), and selective catalytic reduction (SCR). Thirty-six U.S. coal-fired utility boilers have installed SNCR, and reported NO_x reductions achieved at these applications ranged from 15% to 66%. Recently, SCR has been installed at >150 U.S. coal-fired utility boilers. Data on the performance of 20 SCR systems operating in the United States with low-NO_x emissions reflect that in 2003, these units achieved NO_x emission rates between 0.04 and 0.07 lb/10⁶ Btu.     

Spray Charging and Trapping Scrubber for Fugitive Particle Emission Control

The control of fugitive process emissions (FPE) with Spray Charging and Trapping (SCAT) scrubber was evaluated both theoretically and experimentally. The SCAT uses air curtain and/or jets to contain, convey, and divert the FPE into a charged spray scrubber.

Experiments were performed on an 8000 cfm bench-scale spray scrubber to verify the theory and feasibility of collecting fugitive particles with charged water spray. The effects of charge levels on drops and particles, nozzle type, drop size, gas velocity, and liquid/gas ratio on collection efficiency were determined experimentally. The results of the experiments and the comparison between theory and data are presented.

An air curtain was developed for conveying the FPE to the spray scrubber, deflecting the crosswind, and containing hot buoyant plume. The design and air flow field for the air curtain are presented.     

Emission Control in Coking Operations By Use of Stage Charging

At the Clairton Coke Works of the United States Steel Corporation (the world’s largest coke plant), with coal charges of about 30,000 net tons per day, a system designated as “stage charging” has been developed for charging coal into the coke oven chamber without emissions to the atmosphere. The principles of the system are based on controlled sequential flow of the coal from the charging hoppers, during which the oven chamber is maintained under a very slight negative pressure condition by use of steam aspiration in the offtakes for on-the-main charging. The techniques are basic but require knowledge of the coal characteristics, adequate and properly maintained aspirating systems, including clean offtake piping, control of coal volume in the individual hoppers, and last, and probably most important, adherence by the operating crew to specific charging and leveling practices.     

The Formulation of Emission Control Strategies Using a Cubic Polynomial Approximation

Assuming the existence of an ambient air standard for a given pollutant, there is some agreement that emission standards for local area and point sources should be established by formulating and testing various “control strategies” with use of a computer diffusion model. The procedure requires several, perhaps many, computer simulations of pollutant dispersion followed by an analysis of the results of each simulation. Part of this analysis is to include an “optimization” of sorts which is intended to provide a workable control strategy which, in turn, is to indicate required emission level reductions for point sources. This paper is intended to describe and apply an approximation technique which, when used in conjunction with a diffusion model, could be of value in determining acceptable emission levels for point sources.     

Assessment of Dry Sorbenf Emission Control Technologies Part II. Applications

The injection of dry alkaline compounds into the furnace or post-furnace regions of utility boilers to reduce SO₂ is currently under development as a lower cost option to conventional flue gas desulfurization technology. Part I of this paper focused on the science and process development of the various dry sorbent technologies. Part II will address applications of these technologies, including SO₂ removals in full-scale boilers, methodologies for designing sorbent injection systems, power plant impacts, process integration issues, and cost.

Because the dry technologies use the furnace and/or ducts as the chemical contactor, potential impacts on power plant operation and reliability are as critical in assessing the commercial applicability of each technology as SO₂ removal and sorbent utilization. Consequently, the technical and economic feasibility of the various dry processes is highly site specific.     

Assessment of Dry Sorbent Emission Control Technologies Part I. Fundamental Processes

The utility and industrial sectors continue to come under pressure from both national and local regulatory groups to reduce sulfur dioxide emissions. With a trend in the utility industry for life extension, retrofit technologies are likely to play an important role in any SO₂ emission reduction strategy. Potential retrofit technologies include, singly and in combination: coal switching or cleaning, wet or dry FGD, conversion to fluidized bed, and dry sorbent injection. The diversity within the utility industry in terms of unit size, unit age, fuel use, financial base, and geographic location dictates the need for a variety of technologies to address SO₂ emission control. Dry injection processes involving the injection of dry powders into either the furnace or post-furnace region offer the potential for low capital cost retrofitable technologies. However, compared to wet FGD processes, the dry calcium based processes will likely have lower SO₂ removal efficiencies and may pose more plant-wide integration issues that need to be addressed from both an applications and R&D perspective.

This paper provides a critical assessment of dry injection technologies, in two parts. Part 1 focuses on sorbent processes and science. An assessment of the different dry sorbent processes and the effect of process parameters is provided. Emphasis is placed on process limitations and potential avenues to enhance SO₂ removal. Part 2 will deal with applications of the technology, addressing cost, scale-up, and integration issues.

Much of the data included in this paper was presented at the 1986 Joint Symposium on Dry SO₂ and Simultaneous SO₂/NO_x Control Technologies, sponsored by the Electric Power Research Institute and the Environmental Protection Agency and held in June 1986. This paper provides both an overview and an evaluation of the technology, based largely on our analysis of the data and interpretations discussed at this symposium.     

Economic Comparison of Emission Control Systems for Glass Manufacturing Furnaces with Heat Recovery

ABSTRACT

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.     

The Use of Nahcolite Ore and Bag Filters For Sulfur Dioxide Emission Control

This paper describes some technical and economic aspects of the nahcolite ore injection process for the simultaneous removal of fly ash and sulfur oxides from stack gases. The process is capable of removing greater than 99% of the particulate matter and greater than 70% of the sulfur oxides present in such gases. In the process, nahcolite ore, a naturally occurring material containing 70 to 90% sodium bicarbonate, is ground to 90% passing through —200 mesh screens. Approximately 20% of the ground ore is used to precoat the filter bags in a baghouse filter while the remainder of the material is fed into the flue gas Just ahead of the baghouse. The flue gas is drawn through the baghouse by induced draft fans and sent up the stack. Most of the SO₂ and practically all of the fly ash in the flue gas can be removed as the gas passes through the filter bags. The spent nahcolite ore and fly ash are collected and conveyed to waste disposal as landfill, or alternatively processed for insolubilization by coprecipitation prior to landfilling. The technical feasibility of the process has been demonstrated in both bench scale and pilot scale engineering studies. Economic analyses performed for the cases of plants located in the midwest and southwest indicate lower capital costs for the nahcolite injection process when compared to wet scrubbing. On an annual cost basis, the nahcolite ore Injection process is comparable in cost to wet scrubbing for the case of the southwestern power plant, and somewhat more expensive for the case of the midwestern plant.     

排污收费对企业污染控制技术创新激励作用的研究

运用模型方法研究了排污收费和行政手段对企业污染控制技术创新的激励作用,为环境管理政策应用提供了理论依据。结果表明,无论对创新企业还是模拟企业,在“技术创新－创新扩散－最优啮合反应”的技术创新过程中,排污收费更能刺激企业的污染控制技术创新行为。