Sizing and Costing of Electrostatic Precipitators

This is the second of a two-part article that reviews electrostatic precipitation theory, presents size estimating methods, and gives costing procedures for a variety of electrostatic precipitator (ESP) types and sizes. Part I of the article, which appeared in the April 1988 issue of JAPCA, discussed theory and sizing; this part presents costing. Information is given for estimating total capital investment including separate costs for the bare ESP (five types) and auxiliaries. Factors are given for installation and for indirect costs. Direct and indirect annual costs are discussed. An example problem is given.     

Development of a High-Speed Ultraviolet Spectrometer for Remote Sensing of Mobile Source Nitric Oxide Emissions

ABSTRACT

The University of Denver (DU) has developed a new remote sensor for the measurement of mobile source nitric oxide (NO). This system is integrated with an existing infrared remote sensor and is capable of measuring carbon monoxide and hydrocarbons in addition to NO, at a rate of more than 1000 vehicles/hr. The detection limit on a low-emitting vehicle under typical measurement conditions is 24 parts per million NO (3σ). Measurements from this instrument correlated well in a side-by-side comparison with the previous NO remote sensor developed at DU, and we have used this study to confirm a suspected interference by aromatic hydrocarbons in the older instrument. The results of an extended field experiment using the new instrument, conducted in fall 1997, are also presented. The NO emissions of the fleet measured in this study (averaging 15.0 g NO/gal) exhibit a skewed distribution typical of mobile sources. This paper also describes the relationship between NO emissions and model year and NO emissions and vehicle acceleration, as measured by the new remote sensor.     

‘Tolerable’ hillslope soil erosion rates in Australia: Linking science and policy

This paper reviews water-borne soil erosion in Australia in the context of current environmental policy needs. Sustainability has emerged as a central tenet of environmental policy in Australia and water-borne hillslope soil erosion rates are used as one of the indicators of agricultural sustainability in State of the Environment reporting. We review attempts to quantify hillslope erosion rates over Australia and we identify areas at risk of exceeding natural baseline rates. We also review historical definitions of sustainable, or ‘tolerable’ erosion rates, and how to set these rates. There are many ways to estimate hillslope erosion and these can create confusing results. Moreover their application for land management purposes requires nuanced interpretations that ultimately depend on the desired objective of decision-makers. Soil is the earth surficial material that serves as a medium for plant growth and the notion of tolerable soil erosion arose historically to assess the impact of soil loss on agricultural uses. However now that the impact of erosion on aquatic ecosystems been recognized as a major concern for Australia, the concept of tolerable erosion needs to be revised. Here we discuss three definitions of tolerable soil erosion, following recent literature. We derive estimates of long-term agricultural sustainability based on natural soil production rates and discuss this in relation to other defined land-management objectives such as aquatic ecosystem health. We conclude that the desired objectives of land managers must be clearly articulated before questions of ‘where to invest to control erosion’ and ‘how to assess return-on-investment’ can be answered.