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.     

Use of AERMOD to Determine a Hydrogen Sulfide Emission Factor for Swine Operations by Inverse Modeling

This study was conducted to determine both optimal settings applied to the plume dispersion model, AERMOD, and a scalable emission factor for accurately determining the spatial distribution of hydrogen sulfide concentrations in the vicinity of swine concentrated animal feeding operations (CAFOs). These operations emit hydrogen sulfide from both housing structures and waste lagoons. With ambient measurements made at 4 stations within 1 km of large swine CAFOs in Iowa, an inverse-modeling approach applied to AERMOD was used to determine hydrogen sulfide emission rates. CAFO buildings were treated as volume sources whereas nearby lagoons were modeled as area sources. The robust highest concentration (RHC), calculated for both measured and modeled concentrations, was used as the metric for adjusting the emission rate until the ratio of the two RHC levels was unity. Utilizing this approach, an average emission flux rate of 0.57 μg/m(2)-s was determined for swine CAFO lagoons. Using the average total animal weight (kg) of each CAFO, an average emission factor of 6.06 × 10(-7) μg/yr-m(2)-kg was calculated. From studies that measured either building or lagoon emission flux rates, building fluxes, on a floor area basis, were considered equal to lagoon flux rates. The emission factor was applied to all CAFOs surrounding the original 4 sites and surrounding an additional 6 sites in Iowa, producing an average modeled-to-measured RHC ratio of 1.24. When the emission factor was applied to AERMOD to simulate the spatial distribution of hydrogen sulfide around a hypothetical large swine CAFO (1M kg), concentrations 0.5 km from the CAFO were 35 ppb and dropped to 2 ppb within 6 km of the CAFO. These values compare to a level of 30 ppb that has been determined by the State of Iowa as a threshold level for ambient hydrogen sulfide levels.     

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%.     

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.     

Control of Organic Emissions from Surface Coating Operations

ABSTRACT

Step tracer tests were carried out on lab-scale biofilters to determine the residence time distributions (RTDs) of gases passing through two types of biofilters: a standard biofilter with vertical gas flow and a modified biofilter with horizontal gas flow. Results were used to define the flow patterns in the reactors. “Non-ideal flow” indicates that the flow reactors did not behave like either type of ideal reactor: the perfectly stirred reactor [often called a "continuously stirred tank reactor" (CSTR)] or the plug-flow reactor.

The horizontal biofilter with back-mixing was able to accommodate a shorter residence time without the usual requirement of greater biofilter surface area for increased biofiltration efficiency. Experimental results indicated that the first bed of the modified biofilter behaved like two CSTRs in series, while the second bed may be represented by two or three CSTRs in series. Because of the flow baffles used in the horizontal biofilter system, its performance was more similar to completely mixed systems, and hence, it could not be modeled as a plug-flow reactor. For the standard biofilter, the number of CSTRs was found to be between 2 and 9 depending on the airflow rate. In terms of NH₃ removal efficiency and elimination capacity, the standard biofilter was not as good as the modified system; moreover, the second bed of the modified biofilter exhibited greater removal efficiency than the first bed. The elimination rate increased as biofilter load increased. An opposite trend was exhibited with respect to removal efficiency.     

Control of Malodors from Kraft Recovery Operations by Pyrolysis

The major source of malodorous emissions which emanate from kraft mills is the recovery furnace and its associated direct contact evaporator. The primary reasons for this problem are gross furnace overloading and/or inadequate design. Existing recovery furnaces are incapable of carrying out, to an acceptable degree of completion, the complex sequence of physical and chemical steps which describe combustion. These steps are evaporation, sublimination, pyrolysis, recombination, and oxidation. A simplified odor model is presented which establishes the constraints which must be placed on the combustion phase of the recovery operation if environmental concentrations of malodorous compounds are to be held below their respective threshold odor levels. The pyrolysis and recombination steps of combustion have been isolated for study because they encompass the reaction mechanisms responsible for malodorous compound production. The findings of the steady state pyrolysis study indicate that the optimization of pyrolysis appears to be a very desirable process technique for abating alodorous emissions from kraft mills. The comprehensive data obtained in the study has engendered the current design and construction efforts toward a pilot plant operation.     

Fume Control in Rubber Processing By Direct-Flame Incineration

The application of direct-flame incineration to successfully eliminate a smoke-oil-mist and odor problem in the manufacture of rubber-base rug underlay, is presented. The investigation of various air pollution control processes leading to the development and adoption of the direct-flame incineration system, is covered. The rug-underlay curing process incorporating the direct-flame incineration system with primary heat recovery is described. Results and discussion of a source test to determine the effectiveness of direct-flame incineration in this application are included.     

Control of Fine Particulate (PM2.5) Emissions from Restaurant Operations

ABSTRACT

This paper describes efforts to reduce particulate matter (PM) emissions from restaurant operations, including application of an existing control method to a new equipment type. Commercial charbroiling in the South Coast Air Basin results in emissions of approximately 10 tons/day of fine particulate matter ₍PM_2.5) and 1.3 tons/day of volatile organic compounds (VOCs). Over a seven-year period, the South Coast Air Quality Management District worked with industry to develop test methods for measuring emissions from various cooking operations, evaluate control technologies, and develop a rule to reduce these emissions.

Of the two basic types of charbroilers—chain-driven and underfired—underfired produce four times the emissions when equivalent amounts of product are cooked. Cost-effective control technology is currently available only for chain-driven charbroilers. The application of flameless catalytic oxidizers to chain-driven charbroilers was found to effectively reduce emissions by at least 83% and is cost-effective. The catalysts have been used worldwide at restaurants for several years. Research efforts are underway to identify control options for underfired charbroilers.

Implementation of Rule 1138, Control of Emissions from Restaurant Operations, adopted November 14, 1997, will result in reductions of 0.5 tons/day of PM_2.5 and 0.2 tons/day of VOCs. Future rules will result in reductions from underfired charbroilers and possibly other restaurant equipment when cost-effective solutions are available.     

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。     

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.     

Preparation and Use of Spatially and Temporally Resolved Emission Inventories in the San Francisco Bay Region

Three regional agencies recently prepared an Air Quality Maintenance Plan for the San Francisco Bay Area oxidant problem. An Eulerian, photochemical model, LIRAQ, provided the technical basis for the plan recommendations. A major LIRAQ input is an emission inventory accurately resolved to one kilometer and one hour increments. The cooperating agencies prepared such inventories, covering 20,000 sq km, for one base and two future years. Several manual and computer-assisted techniques were developed to utilize a variety of independent data bases. Population, land use, employment and transportation data were oganized into a common system of coordinates and units to produce the needed spatial input. Estimates of hourly variation were made by source category based on production rates, fuel use, traffic patterns, flight schedules, and other factors. The result was a series of consistent, detailed inventories which provide a powerful air quality modeling and planning tool. The detail is attained at considerable expense, but the cost is easily justifiable when compared to implementation costs for control strategies.     

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.     

Improvement of Air Quality in a Small Indoor Ice Arena by Effective Emission Control in Ice Resurfacers

ABSTRACT

The effectiveness of a new emission control system in the ice resurfacer was tested in an exhaust gas emission laboratory, and the improvement of the air quality in a small, enclosed ice arena was demonstrated in a 4.5-month follow-up study. The emission control system consisted of a lambda sensor-controlled fuel supply and a three-way metallic catalyst that were applied to a propane-fueled resurfacer. In the laboratory tests, the engine emissions of carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NO ) reduced simultaneously by 91, 90, and 96%, respectively. During the air quality follow-up the median 1-hour average nitrogen dioxide (N0₂) concentration inside the ice arena decreased from 430 ug/m³ (230ppb) to 58 ug/m³ (31 ppb), and that of CO decreased from 4.4 mg/m³ (3.8 ppm) to 1.5 mg/m³ (1.3 ppm). The new emission control system proved to be a feasible, reliable, and effective means to improve the indoor air quality in the ice arena. However, continuous mechanical ventilation was necessary during all business hours in order to achieve and maintain a fully acceptable air quality with this technology.