Smoke point

Performed by ASTM D 1322, this test determines the maximum flame height in a lamp without smoke forming. Normally high values represent 

Kerosene can vary widely in its burning quality as measured by carbon deposition, smoke formation, and flame radiation. This is a function of hydrocarbon composition—paraffins have excellent burning properties, in contrast to those of the aromatics (particularly the polynuclear aromatic hydrocarbons). As a control measure the smoke point test (ASTM D-1322, IP 57) gives the maximum smokeless flame height in millimeters at which the fuel will burn in a wick-fed lamp under prescribed conditions. The combustion performance of wide-cut fuels correlates well with smoke point when a fuel volatility factor is included, because carbon formation tends to increase with boiling point. A minimum smoke volatility index (SVI) value is specified and is defined as  

However, the smoke point is not always a reliable criterion of combustion performance and should be used in conjunction with other properties. Various alternative laboratory test methods have previously been specified such as the lamp burning test (ASTM D-187, IP 10) and a limit on the polynuclear aromatic content (ASTM D-1840), as well as the luminometer number (ASTM D-1740). The test apparatus is a smoke point lamp modified to include a photoelectric cell for flame radiation measurement and a thermocouple to measure temperature rise across the flame. The fuel luminometer number (LN) is expressed on an arbitrary scale on which values of 0 to 100 are given to the reference fuels tetralin and ixo-octane, respectively. 

The kinematic viscosity of many petroleum fuels is important for their proper use, for example, flow of fuels through pipelines, injection nozzles, and orifices, and the determination of the temperature range for proper operation of the fuel in burners. 

The quantity of oil flowing up a wick is related to the height of the top of the wick above the level of oil in the container and the viscosity and surface 

Contamination of kerosene with heavy oil may also be revealed by the test method that is used to determine the amount of residue left by evaporation (ASTM D-381, IP 131), although this depends on the relative volatility of the contaminant. 

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In order to maintain high energy efficiency and ensure a long service life of the materials of construction in the combustion chamber, turbine and jet nozzle, a clean burning flame must be obtained that minimizes the heat exchange by radiation and limits the formation of carbon deposits. These qualities are determined by two procedures that determine respectively the smoke point and the luminometer index. 

The smoke point corresponds to the maximum possible flame height (without smoke formation) from a standardized lamp (NF M 07-028). The values commonly obtained are between 10 and 40 mm and the specifications for TRO fix a minimum threshold of 25 mm. The smoke point is directly linked to the chemical structure of the fuel it is high, therefore satisfactory, for the linear paraffins, lower for branched paraffins and much lower still for naphthenes and aromatics. 

Products excellent properties Kerosene smoke point 25-30 mm Diesel cetane number 55-60 Residue BMCl 15 VI 5= 125 No post-treatment... 

Hydrotreating processes are applied to finished products to improve their characteristics sulfur content, cetane number, smoke point and the aromatics and olefins contents. 

In regard to kerosene, the hydrotreating processes are used to reduce aromatics in order to improve the smoke point. 

Smoke point NF M 07-028 ISO 3014 ASTM D 1322 Mciximum flame height with no smoking... 

Aromatic and Nonaromatic Hydrocarbon Separation. Aromatics are partially removed from kerosines and jet fuels to improve smoke point and burning characteristics. This removal is commonly accompHshed by hydroprocessing, but can also be achieved by Hquid-Hquid extraction with solvents, such as furfural, or by adsorptive separation. Table 7 shows the results of a simulated moving-bed pilot-plant test using siHca gel adsorbent and feedstock components mainly in the C q—range. The extent of extraction does not vary gready for each of the various species of aromatics present. SiHca gel tends to extract all aromatics from nonaromatics (89). 

The products manufactured are predominantiy paraffinic, free from sulfur, nitrogen, and other impurities, and have excellent combustion properties. The very high cetane number and smoke point indicate clean-burning hydrocarbon Hquids having reduced harmful exhaust emissions. SMDS has also been proposed to produce chemical intermediates, paraffinic solvents, and extra high viscosity index (XHVI) lubeoils (see Lubrication and lubricants) (44). 

Plus naphthalenes 3 vol % max unless smoke point exceeds 25. 

Specifications for gas turbine fuels prescribe test limits that must be met by the refiner who manufactures fuel however, it is customary for fuel users to define quality control limits for fuel at the point of delivery or of custody transfer. These limits must be met by third parties who distribute and handle fuels on or near the airport. Tests on receipt at airport depots include appearance, distfllation, flash point (or vapor pressure), density, freezing point, smoke point, corrosion, existing gum, water reaction, and water separation. Tests on delivery to the aircraft include appearance, particulates, membrane color, free water, and electrical conductivity. 

It should also be noted that this process does not alter the smoke point. Smoke point is a function of aromatics content and mild Hydrofining does not hydrogenate aromatics. To accomplish this, treating over a more active catalyst such as nickel tungstate at pressures of at least 800 psig is required. 

Conventional Hydrofining of diesel oils does not improve octane number because octane number improvement, like smoke point improvement in kerosenes, requires samration of aromatics. Higher pressures are needed to gain appreciable aromatics samration and cetane number improvement. 

Other important properties include Hash point, volatility, viscosity, specific gravity, cloud point, pour point, and smoke point. Most of these properties are related directly to the boiling range of the kerosene and are not independently variable. The flash point, an index of fire hazard, measures the readiness of a fuel to ignite when exposed to a flame. It is usually mandated by law or government regulation to be 120° or 130° F (48° or 72° C), Volatility, as measured... 

Allan, K.M., Kaminski, J.R., Bertrand, J.C., Head, J., and Sunderland, P.B., Laminar smoke points of candle flames, presented at 5th US Combustion Meeting of the Combustion Institute, Paper No. D32, San Diego, CA, March 25-28,2007. 

Aromatics, olefins and in general, unsaturated compounds undergo hydrogenation reactions, usually unwanted due to their detrimental effect on the operating costs, derived from an excessive consumption of hydrogen. Aromatic saturation, however, is used in jet fuel to improve the smoke point and in diesel for cetane enhancement. In the case of gasoline, extreme hydrogenation leads to a deterioration of the fuel performance parameters. 

The smoking point of butter is the temperature at which partial combustion starts, yielding smoke. An oil or fat is only safe to cook with below its smoke point. 

In addition to CN and ON, the smoke point (SP), which is the maximum smoke-free laminar diffusion flame height, has been employed widely to evaluate the tendency of different fuels to form soot. This tool was first applied to kerosenes, later diesel, and then jet engine fuels.19,20 Researchers have tried to relate smoke points of pure compounds to their molecular structure. It was found that the inverse of smoke point, which measures the potential of a fuel to form soot, increases from n-paraffins to iso-paraffins to alkylbenzenes to naphthalenes.21,22 Since smoke points vary with experimental conditions, the concept of a threshold soot index (TSI), which is calculated from the smoke point, molecular weight, and experimental constants, has been used to compare the soot-formation tendencies of different fuel molecules.23... 

Smoke flavoring, 12 48 Smoke generation tests, 19 588 Smoke point, of fats and oils, 10 822 Smoke retardants, molybdenum compounds in, 17 39 Smoke suppression, by ethylene-acrylic elastomers, 10 700 Smoking, age-related macular degeneration and, 17 659 Smoky quartz color, 7 337... 

Hydrogen sulfide At low levels, hydrogen sulfide can inhibit aromatic ring saturation. This results in higher-octane gasoline and low-smoke-point jet fuel. At high concentrations, cracking catalyst activity is adversely affected. 

This problem is difficult to resolve through finishing processes. Contamination with higher-boiling-point materials may also influence the JFTOT and smoke point values. Often, fuel contaminated with other materials must be reprocessed. 

Will cause a reduction in the smoke point of kerosene... 

Smoke Point A measurement of the burning quality of jet fuel, kerosene, and lamp oils. This value is determined by ASTM D-1322. 

S.P. = Smoke point in millimeters as determined by ASTM Method D1322... 

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