Blue Flame Compositions

Black powder] as a propellant, 136-137 as an igniter, 125 burning rate of, 114, 115, 117 composition of, 1 factories, 3 gas production by, 33 history of, 3-5 properties of, 1-2 thermogram of, 43 Blue flame compositions, 160-162 Bond... 

Several formulas for blue flame compositions are given in Table 711- An extensive review of blue and purple flames, concentrating on potassium perchlorate mixtures, has been published by Shimizu [131. 

TABLE 8.13 Blue Flame Compositions Composition % by Weight... 

Whereas there is no universally accepted specification for marketed natural gas, standards addressed in the United States are Hsted in Table 6 (8). In addition to these specifications, the combustion behavior of natural gases is frequently characteri2ed by several parameters that aid in assessing the influence of compositional variations on the performance of a gas burner or burner configuration. The parameters of flash-back and blow-off limits help to define the operational limits of a burner with respect to flow rates. The yeUow-tip index helps to define the conditions under which components of the natural gas do not undergo complete combustion, and the characteristic blue flame of natural gas burners begins to show yellow at the flame tip. These... 

Cool Flames. An intriguing phenomenon known as "cool" flames or oscillations appears to be intimately associated with NTC relationships. A cool flame occurs in static systems at certain compositions of hydrocarbon and oxygen mixtures over certain ranges of temperature and pressure. After an induction period of a few minutes, a pale blue flame may propagate slowly outward from the center of the reaction vessel. Depending on conditions, several such flames may be seen in succession. As many as five have been reported for propane (75) and for methyl ethyl ketone (76) six have been reported for butane (77). As many as 10 cool flames have been reported for some alkanes (60). The relationships of cool flames to other VPO domains are depicted in Figure 6. 

Even earlier, in the seventeenth Century, John Bate recorded the use of antimony sulhde to produce a blue flame in his Book of Fireworks in 1635. The same author also used iron scale in some of his compositions to give rockets a more luminous tail. 

Some of the best blue flames are obtained from compositions based on potassium perchlorate, cuprous chloride, hexachloroethane, polyisobutylene, pyrotechnic copper powder and cellulose dust. 

The main species responsible for the blue flame from such a composition is cuprous chloride, CuCI hence the use of this salt together with the chlorine producer (hexachloroethane) and a source of extra copper (pyrotechnic copper powder). The cellulose dust acts as a moderator to control the burning rate of the pressed composition. 

T. Shimizu, "Studies on Blue and Purple Flame Compositions Made With Potassium Perehlorate," Pyrotechnica VI, Pyrotechnica Publications, Austin, Texas, 1980. 

Copper-II-oxide forms a black to dark brownish-black amorphous or crystalline powder. The powder is insoluble in water and most organic solvents, but soluble in ammonia solution, acids and alkalies. The powder, after being roasted at high temperature for sometime, may become resistant to acids. Copper-II-oxide is widely used in the manufacture of fireworks and other pyrotechnic compositions for imparting a blue flame. 

If a spiral of platinum wire is heated in a bottle of hydrogen sulphide gas, a yellow powder and an invisible gas are formed the powder burns with a pale blue flame, producing a choking vapor, and the invisible gas burns with a colorless, hot flame. What evidence do these facts present about the composition of hydrogen sulphide ... 

Figure 5 Product compositions and surface temperatures (upstream and downstream ends) for a 7-mm-Iong, 12-wt%-Pt extruded monolith (400 cells/in. ) at 2 5-sIpm total flow. The H2 and CO sclectivities are lower than those reported in previous experiments because the reactor was not insulated. A heterogeneous steady-state reaction is maintained for rich (> 12%) compositions, while at leaner compositions, a combination of heterogeneous and homogeneous reactions (a blue flame) is observed, with multiple ignited steady-states for compositions between 10 and 12% CH4. (From Ref. 7.)...

Free Cyanogen.—When mercuric oxide is heated, oxygen is set free as a gas and metallic mercury is left. A similar change occurs when mercuric cyanide is heated. Mercury is left and a gas is given off which is extremely poisonous, colorless, soluble in water, and which burns with a blue flame. This substance is known as cyanogen and has the composition (CN)2. 

The CuO band(red) occurs, when the flame has an excessive amount of oxygen. It appears at the top of the blue flame of a composition which contains copper or copper salts. However it is very weak and does not distvirb the blue colour. 

A reddish powder with pretty metal lustre. The atmic weight is 63.55. Specific gravity 8.9 it melts at 1083 C and boils at 2595 C. Gradually it is co ated with a film of basic copper carbonate in the wet state by the action of moisture and carbon dioxide gas in the air. When it is added to a composition which contains ammonium perchlorate, a pretty blue flame is obtained 3% copper powder is adequate. Neverthless ammonium perchlorate reacts with copper powder generating heat and ammonia gas in the presence of moisture, and the composition must be well protected from the moisture. 

However, the effect of hydrocarbon type composition is greater with wick-fed yellow flame burners than with wick-fed blue flame burners. With the former, kerosenes that are mainly paraffinic burn well in lamps with a poor draft, whereas under the same conditions kerosenes containing high proportions of aromatics and naphthenes burn with a reddish or even smoky flame. 

Anthracite 92-95 800-930 30.2-32.5 High carbon coal that approach graphite in structure and composition. It is hard, compact, and shiny dark, with generally a conchoidal fracture. It is difficult to ignite and burn with a smokeless blue flame... 

Copper oxide (CuO), basic copper carbonate CuC03 Cu(0H)2, and copper sulfate, available commercially as CuS04 5H20, are among the materials used in blue flame mixtures. Potassium perchlorate and ammonium perchlorate are the oxidizers found in most blue compositions. Potassium chlorate would be an ideal choice because of its ability to sustain reaction at low temperatures (ranember, CuCl is unstable above 1,200°C), but copper chlorate is an extremely reactive material. The chance of it forming should a blue mixture get wet precludes the commercial use of KCIO3. 

T. Shimizu, Studies on blue and purple flame compositions made with potassium perchlorate, in Pyrotechnica VI, Austin, TX Pyrotechnica Publications, 1980. 

It is also astonishing how the rich blue of a cornflower (Centaurea cyanus) and the majestic red flame of the com poppy (Papaver rheas) each derive from the same chromophore - again based on an anthrocyanidin. The pH of cornflower and poppy sap does not vary with soil composition, which explains why we see neither red cornflowers nor blue com poppies. 

CuCl 435-526 Band spectrum. Present when composition contains chlorine. Main species responsible for blue colour in Cu flames. 

Flame color depends on fuel composition. Gas often burns blue, but heavy fuel oil burns yellow. A yellow flame is caused by thermal cracking of the fuel. There is nothing wrong with a yellow flame it is the general shape of the flame which is important. If in doubt as to the right flame shape for a particular furnace, contact the burner manufacturer for details. 

CH3)2Se(N03)0H. Concentration of the mother-liquor from these gives colourless prisms having a faint, unpleasant smell, and melting at 90 5° C. The composition of the product appears to be represented by a combination of nitrate and oxide, (CH3)2Se(N03)2.(CHg)2Se0. The compound is volatile above 100° C. and burns with the blue characteristic selenium flame. In water it is readily soluble, it is sparingly soluble in alcohol, and insoluble in ether. 

Copper-I-chloride forms a white crystalline powder, which is stable in dry air, but tends to turn yellow, green, blue, or brown on exposure to moisture, air, and light. Store dry in airtight amber glass bottles. The dry crystals have a melting point of 430 Celsius. The crystals are relatively insoluble in water, with partial decomposition, but are soluble in concentrated hydrochloric acid, and ammonia solutions. Copper-I-chloride can be used in pyrotechnic compositions, for imparting cool effects to the flames. Copper-I-chloride is a very useful catalyst for use in chemistiy. 

The band CuCl appears in a flame which is rich in chlorine or hydrogen chloride gas, and gives the flame a pretty violet blue colour. For example, a composition of 75% ammonium perchlorate, 15% shellac and 10% Paris green produces such a coloured flame. The band CuCl seems to decompose at high temperatures, and it is difficult to produce blue with this band in the high temperatiire class flames, unless the magnesium content is decreased to about 10%. 

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