Plume Dispersion in a Mountainous River Valley during Spring

The dispersion of hot plumes emitted from a smelter complex located In the Columbia River Valley, British Columbia, was evaluated under stable and neutral conditions during two mornings In spring. Spatial measurements of SO₂ and temperature within the plume were obtained by immersion probing using fast response helicopter and automobile mounted Instrumentation. In addition, meteorological measurements of vertical wind and temperature profiles at, and downwind from, the smelter were obtained from minisonde balloon releases. With weak down-valley winds, it was found that the plume axis elevations were generally lower during both stable and neutral conditions than would be predicted by Briggs plume-rise formulae. In contrast, plume dispersion, although confined in the horizontal by the steep valley walls during both stability regimes, was significantly enhanced by exceptionally good lateral mixing, particularly close to the source.     

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.     

Effects of Nighttime Chemistry upon the Transport of Ozone and Ozone Precursors

It has been recognized for several years that ozone in rural areas can exceed the National Ambient Air Quality Standard (NAAQS) for photochemical oxidant whirh was 0.08 ppm for one hour, not to be exceeded more than once per year. During the summer of 1973, the NAAQS was exceeded from 15 to 37% of the time at four rural monitoring sites in Maryland, Pennsylvania, Ohio, and West Virginia.¹ This is a greater violation rate than is found in many urban areas. Dimitriades and Altshuller² have enumerated four possible sources for this rural ozone: (a) transport from urban areas, (b) local photochemical generation from urban ozone precursors, (c) local photochemical generation from precursors of rural origin which may be man-made or natural, and (d) injection of stratospheric ozone into the rural area. This paper considers the chemistry pertinent to the first two of these possible sources of rural ozone, namely the long distance (overnight) transport of ozone and ozone precursors.     

Electrostatic Stimulation of Fabric Filtration

The concept of electrostatic stimulation of fabric filtration (ESFF) has been investigated at pilot scale. The pilot unit consisted of a conventional baghouse in parallel with an ESFF baghouse, allowing direct comparison. All results reported in this paper are for pulse-cleaned bags in which the electric field was maintained parallel to the fabric surface. The performance of the ESFF baghouse has been superior to the parallel conventional baghouse by several measures. The ESFF baghouse demonstrated: (1) a reduced rate of pressure drop increase during a filtration cycle, (2) lower residual pressure drop, (3) stable operation at higher face velocities, and (4) improved particle removal efficiency. These benefits can be obtained with only minor modifications to conventional pulse-jet hardware and at low electrical power consumption. The indicated ability to operate at increased face velocities with only modest expenditure for electrical hardware leads to very favorable economic projections.     

Sensitivity Studies of the Effects of Model Formulation on the Evaluation of Control Strategies for Photochemical Air Pollution Formation in the United Kingdom

In the OZIPP (ozone isopleth plotting package, developed by United States Environmental Protection Agency) a number of model specific assumptions with respect to chemical and physical processes are made. These assumptions are introduced into an alternative model developed at AERE Harwell, United Kingdom, in which a detailed chemistry and mixture of organic emissions is included. The impact on the AERE Harwell model results of the assumptions made in OZIPP of omitting ground removal of ozone (O₃) and peroxyacetylnitrate (PAN) and of employing an incomplete PAN chemistry and adopting a reaction rate coefficient of the key reaction NO + HO₂ → NO₂ + OH which is a factor 10 lower than the accepted value, are discussed. The composition of the organic emissions is an important model parameter, and it is shown how grouping of nonmethane hydrocarbon (NMHC) emissions into a small group of NMHC thought to be representative, often implies that O₃ and other pollutants are overestimated. The O₃ isopleth diagram for London constructed using the AERE Harwell model gives a somewhat different picture from that obtained with OZIPP. OZIPP in general predicts that NO_x control or combined hydrocarbon(HC) and NO_x control is efficient with respect to O₃ reduction whilst the AERE Harwell model predicts that HC control alone usually is more efficient than combined HC and NO_x control. Furthermore NO_x control alone may often increase the O₃ burden downwind in the AERE Harwell model.