Hydrocarbon Releases

Forests can act as sources of some of the trace gases in the atmosphere, such as hydrocarbons, hydrogen sulfide, NO, and NH3. Forests have been identified as emitters of terpene hydrocarbons. In 1960, Went (10) estimated that hydrocarbon releases to the atmosphere were on the order of 108 tons per year. Later work by Rasmussen (11) suggested that the release of terpenes from forest systems is 2 x 10 tons of reactive materials per year on a global basis. This is several times the anthropogenic input. Yet, it is important to remember that forest emissions are much more widely dispersed and less concentrated than anthropogenic emissions. Table 8-2 shows terpene emissions from different types of forest systems in the United States. 

The reasons for performing a source test differ. The test might be necessary for one or more of the following reasons (1) To obtain data concerning the emissions for an emission inventory or to identify a predominant source in the area. An example of this would be determination of the hydrocarbon release from a new type of organic solvent used in a degreasing tank. 

CHLORINATED HYDROCARBONS Hydfoearbons containing ehlorine atoms, e.g. triehloroethylene. Some of these ehemieals aeeumulate in the food chain and do not readily degrade. Some plastics which contain certain chlorinated hydrocarbons release dioxins into the ah, when burnt at low temperatures. 

Combinations of water and hot hydrocarbon releases which could result in steam generation and pressure surges. 

Most sulfur compounds can be removed from petroleum streams through hydrotreatment processes, where hydrogen sulfide is produced and the corresponding hydrocarbon released. Hydrogen sulfide is then absorbed in a suitable absorbent and recovered as sulfur (Chapter 4). 

C06-0100. Use average bond energies (Table 6-2) to compare the combustion energies of ethane, ethylene, and acetylene. Calculate which of these hydrocarbons releases the most energy per gram. 

Hydrocarbon formation involves the removal of one carbon from an acyl-CoA to produce a one carbon shorter hydrocarbon. The mechanism behind this transformation is controversial. It has been suggested that it is either a decarbonylation or a decarboxylation reaction. The decarbonylation reaction involves reduction to an aldehyde intermediate and then decarbonylation to the hydrocarbon and releasing carbon monoxide without the requirement of oxygen or other cofactors [88,89]. In contrast, other work has shown that acyl-CoA is reduced to an aldehyde intermediate and then decarboxylated to the hydrocarbon, releasing carbon dioxide [90]. This reaction requires oxygen and NADPH and is apparently catalyzed by a cytochrome P450 [91]. Whether or not a decarbonylation reaction or a decarboxylation reaction produces hydrocarbons in insects awaits further research on the specific enzymes involved. 

The most destructive incidents in the petroleum and related industries are usually initiated by an explosive blast that can damage and destroy unprotected facilities. These blasts have been commonly equated with the force of a TNT explosion and are quite literally a "bomb". The protection of hydrocarbon and chemical industries is in rather a unique discipline by itself, which requires specialized techniques of mitigation and protection in a systems based approach. The first step in this approach is to understand the characteristics of hydrocarbon releases, fires and explosions. 

Hydrocarbon releases in the petroleum industry are either gaseous, mists or liquids and are either atmospheric releases or pressurized. Gas and mist releases are considered more significant since they are readily ignitable since they are in the gas state and due to the generation of vapor clouds which if ignited are instantly destructive in a widespread nature versus liquid fires that may be less prone to ignition, generally localized and relatively controllable. 

If a hydrocarbon release is ignited, various possible fire and explosion events may result. The events are primarily dependent on the type of material, the rate of release, the item at which it is ignited and nature of the surrounding structure. 

Leak Estimation - A mathematical model of the probability and amount of potential hydrocarbon releases that may occur from selected processes or locations. 

Fire and Smoke Models - A mathematical estimation model depicting the duration and extent of heat, flame and smoke that may be generated from the ignition of a hydrocarbon release. The results of these estimates are compared against protection mechanisms (e.g., firewater, fireproofing, etc.) afforded to the subject area to determine adequacy. 

Surface temperature of exposed equipment may pose the most readily available ignition source in a hydrocarbon facility. Hot surfaces should be insulated, cooled or relocated, when they pose a threat of ignition, to hydrocarbon release areas. Required equipment should be rated to operate below the autoignitiion temperature of the gas or vapor that may be encountered. 

A standard fire duration (e g., 2 hours) is applied and a high temperature fire (i.e., UL 1709) is normally assumed from the hydrocarbon release sources. 

Various simple and sophisticated fire and gas detection systems are available to provide early detection and warnings of a hydrocarbon release which supplement process instrumentation and alarms. The overall objective of fire and gas detection systems are to warn of possible impending events that may be threatening to life, property of continued business operations, that are external to the process operation. 

Hydrocarbon materials, 20 180 Hydrocarbon propellants, 2 775 physical properties of, 2 776t Hydrocarbon raw materials, 23 686-687 Hydrocarbon release hazard, 20 627 Hydrocarbon remediation, technologies for, 23 112... 

Petroleum products themselves are the source many of the components but do not define total petroleum hydrocarbons. Knowing the composition of petroleum products does assist in defining the potential hydrocarbons that become environmental contaminants, but any ultimate exposure is determined also by how the product changes with use, by the nature of the release, and by the environmental fate of the hydrocarbons released. When petroleum products are released into the environment, changes occur that significantly affect their potential effects. Physical, chemical, and biological processes change the location and concentration of hydrocarbons at any particular site. 

Many refineries unintentionally release, or have released, liquid hydrocarbons to groundwater and surface waters. At some refineries contaminated groundwater has migrated off-site and resulted in continuous seeps to surface waters. Although the actual volume of hydrocarbons released in such a manner is relatively small, there is the potential to contaminate large volumes of groundwater and surface water, possibly posing a substantial risk to human health and the environment. 

In 1974, 28 people died in an explosion resulting from a large release of cyclohexane in Flixborough, U.K. The source of the hydrocarbon release was a failed expansion joint in a section of 20-inch (508-mm) diameter pipe. Investigation revealed the pipe had been designed with little technical input as a temporary bypass for a reactor that had been removed after it cracked. 

Critics of waste incineration argue that these plants often create more environmental problems than they solve. They point out, for example, that incinerators are a major source of dioxin, mercury, and halogenated hydrocarbon release into the atmosphere. In addition, incinerators are very expensive to build and to maintain, and they provide fewer jobs to members of the surrounding community than other methods of solid waste disposal. Also, companies have a dismal record of siting incinerators in disadvantaged communities, where residents suffer the worst consequences of incinerator use. Finally, waste-to-energy incinerators are of little value in tropical and subtropical countries, where the cost of plants and the availability of additional energy sources make them impractical. 

Environmentalfy relevant metabolites include hydrocarbons released fcomEucalyptus forests. They imdergo oxidation by aerial dioxygen to give carboxylic acids that form aerosols, influencing adversely tte climate (Kavouras 1998). 

Hydrocarbons release a lot of energy when ignited. Where does this energy come from ... 

Fogelqvist E, Tanhua T (1995) Iodinated C1-C4 Hydrocarbons Released from Ice Algae in Antarctica. In Grimvall A, de Leer EWB (eds) Naturally-Produced Organohalogens. Kluwer, Dordrecht, p 295... 

The combustion of a saturated hydrocarbon releases 657 kJ per mole of -CH2- groups and 779 kJ per mole of -CH3 groups in the hydrocarbon. How much energy is released by the combustion of 1.00 L of liquid tetradecane (molecular formula C14H30), a major component of kerosene The density of tetradecane is 0.764 g/mL. 

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