Emission from Heat Sources

Several actinide nuclides have found other applications. Heat sources made from kilogram amounts of Pu have been used to drive thermoelectric power units in space vehicles. In medicine, Pu was applied as a long-lived compact power unit to provide energy for cardiac pacemakers and artificial organs. Am has been used in neutron sources of various sizes on the basis of the (a,n) reaction on beryllium. The monoenergetic 59-keV y radiation of Am is used in a multitude of density and thickness determinations and in ionization smoke detectors. Cf decays by both a emission and spontaneous fission. One gram of Cf emits 2.4 10 neutrons per second. "Cf thus provides an intense and compact neutron source. Neutron sources based on Cf are applied in nuclear reactor start-up operations and in neutron activation analysis. 

Carbon monoxide was discovered in 1776 by heating a mixture of charcoal and 2inc oxide. It provided a source of heat to industry and homes as a component of town gas and was used as a primary raw material in German synthetic fuel manufacture during World War II its compounds with transition metals have been studied extensively (see Carbonyls). Most recently, carbon monoxide emission from vehicle exhausts has been recognized as a primary source of air pollution (qv). 

Proper selection and sizing of ventilation systems require knowledge of emissions from internal contaminant and heat sources and an understanding of the mechanisms and characteristics of air and contaminant movement. 

Airborne contaminant movement in the building depends upon the type of heat and contaminant sources, which can be classified as (1) buoyant (e.g., heat) sources, (2) nonbuoyant (diffusion) sources, and (d) dynamic sources.- With the first type of sources, contaminants move in the space primarily due to the heat energy as buoyant plumes over the heated surfaces. The second type of sources is characterized by cimtaminant diffusion in the room in all directions due to the concentration gradient in all directions (e.g., in the case of emission from painted surfaces). The emission rare in this case is significantly affected by the intensity of the ambient air turbulence and air velocity, dhe third type of sources is characterized by contaminant movement in the space with an air jet (e.g., linear jet over the tank with a push-pull ventilation), or particle flow (e.g., from a grinding wheel). In some cases, the above factors influencing contaminant distribution in the room are combined. 

The airflow rate from a heat source can then be calculated as half of the flow from a source with a heat emission of... 

When several heat sources are located close to each other, the plumes may merge into a single plume see Fig. 7.72. In this case, the source should he regarded as one single source, with the heat emission equal to the sum ot the heat eiiiissiot) from each of the stturccs ... 

Apart from g Pu, which is a nuclear fuel and explosive, the transuranium elements have in the past been produced mainly for research purposes. A number of specialized applications, however, have led to more widespread uses. I Pu (produced by neutron bombardment of I Np to form 93 Np which decays by jS-emission to 94Pu) is a compact heat source (0.56 Wg as it decays by a-emission) which, in conjunction with PbTe thermoelectric elements, for instance, provides a stable and totally reliable source of electricity with no moving parts. It has been... 

The SO2 in the atmosphere is derived from two sources. Firstly, from the aerial oxidation of H2S produced naturally (see later) and secondly from the combustion of sulphur-containing fuels. In industrialised countries the second source predominates, but on a global scale only about one-fifth of the total sulphur pollution is derived from human activity. In 1969, the total sulphur emission, expressed in terms of SO2, from burnt fuel in the UK was 6-06 X 10 tons. In densely populated countries sulphur pollution levels arc very much related to the domestic heating cycle, and in the UK maximum... 

The major emissions from the combustion of fuel are C02, SO, NO and particulates14. The products of combustion are best minimized by making the process efficient in its use of energy through efficient heat recovery and avoiding unnecessary thermal oxidation of waste through minimization of process waste. Flue gas emissions can be minimized at source by ... 

Natural sources of airborne nickel include soil dust, sea salt, volcanoes, forest fires, and vegetation exudates and account for about 16% of the atmospheric nickel burden (Kasprzak 1987 WHO 1991 Chau and Kulikovsky-Cordeiro 1995). Human sources of atmospheric nickel — which account for about 84% of all atmospheric nickel — include emissions from nickel ore mining, smelting, and refining activities combustion of fossil fuels for heating, power, and motor vehicles ... 

The most common conventional gas source is an electron impact (El) source. This consists of a metal chamber with a volume of a few cm3, through which the sample flows in the form of a gas. Electrons produced by thermionic emission from a heated tungsten filament are passed through this gas, and accelerated by a relatively low voltage ( 100eV), causing ionization within the sample gas. A plate inside the chamber carries a low positive potential (the repeller ) which ejects the positive ions into a region which contains a series of plates (called lenses) and slits, which serve to focus, collimate, and accelerate the ion beam into the next part of the system... 

Air emissions from a petroleum distillation unit include emissions from the combustion of fuels in process heaters and boilers, fugitive emissions of volatile constituents in the crude oil and fractions, and emissions from process vents. The primary source of emissions is combustion of fuels in the crude preheat furnace and in boilers that produce steam for process heat and stripping. When operating in an optimum condition and burning cleaner fuels (e.g., natural gas, refinery gas), these heating units create relatively low emissions of sulfur oxides, (SO c), nitrogen oxides (NO c), carbon monoxide (CO), hydrogen sulfide (H2S), particulate... 

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