Burner heads temperature

Enclosed flares are composed of multiple gas burner heads placed at ground level in a staeklike enclosure that is usually refractory or ceramic lined. Many flares are equipped with automatic damper controls that regulate the supply of combustion air depending on temperature which is monitored upstream of the mixing, but inside the staek. This class of flare is becoming the standard in the industry due to its ability to more effectively eontrol emissions. Requirements on emissions includes carbon monoxide limits and minimal residence time and temperature. Exhaust gas temperatures may vary from 1,000 to 2,000 F. 

In flame emission spectrometry, a hot flame is required for the analysis of a large number of elements, and the nitrous oxide-acetylene flame is used. The oxy-acetylene flame has a high burning velocity and cannot be used with a conventional premix burner. The nitrous oxide-acetylene flame can, however, be used with a premix burner. Because of its high temperatures, a special, thick, stainless steel burner head must be used to prevent it from melting. A cool air-propane or similar flame is preferred for the flame emission spectrometry of the easily excited elements sodium and potassium because of decreased ionization of these elements. 

So matters stood until John Willis (17) in Australia found that a combination of nitrous oxide and acetylene would not only dissociate refractory compounds, but could also be used in premix burners with minor modifications. The burner head was changed in only two ways the material was thickened to withstand the higher temperature, and the slot was shortened to minimize the potential of flashback. 

Heated Chamber Burner. One approach, which is now being offered commercially, is a burner in which the mixing chamber is heated to a temperature between 300 and 500°C. by infrared radiation. After introduction, the sample is converted into a vapor. It then passes into a cooling chamber, where the steam is condensed and allowed to flow out of a drain tube. In the ideal case, only the solid components of the sample are passed into the burner head. The heated chamber system overcomes the previously noted factor that standard premix burners are only 5% to 10% eflScient. By being able to use all of the sample that had been introduced, the heated chamber burner can produce ten to twenty times higher absorption for a given concentration. 

Amos and Willis suggested another combination of fuel and oxidant, acetylene and nitrous oxide, as another approach to the analysis of refractory elements. The combination of acetylene and nitrous oxide produces a high-temperature flame (2950°C) with little free oxygen to react with the metal elements. This flame is now very successfully used in atomic absorption spectroscopy and permits satisfactory atomic absorption analysis for many refractory elements. Use of nitrous oxide and acetylene requires a burner head that will withstand the temperatures produced by the flame. A common burner head for this combination of fuel and oxidant is 5 cm long and 0.05 cm wide. 

The most common fuel-oxidant combination is acetylene and air, which produces a flame temperature of 2 400-2 700 K (Table 20-1). When a hotter flame is required for refractory elements (those with high boiling points), acetylene and nitrous oxide is usually the mixture of choice. The height above the burner head at which maximum atomic absorption or emission is observed depends on the element being measured, as well as flow rates of sample, fuel, and oxidant. These parameters can be optimized for a given analysis. 

A. Trifluoromethanesulfonic Anhydride. To a dry, 100-ml., round-bottomed flask are added 36.3 g. (0.242 mole) of trifluoromethane-sulfonic acid (Note 1) and 27.3 g. (0.192 mole) of phosphorus pentoxide (Note 2). The flask is stoppered and allowed to stand at room temperature for at least 3 hours. During this period the reaction changes from a slurry to a solid mass. The flask is fitted with a short-path distilling head and then heated first with a stream of hot air from a heat gun and then with the flame from a small burner. The flask is heated until no more trifluoromethanesulfonic anhydride distills, b.p. 82-115°. The yield of the anhydride, a colorless liquid, is 28.4-31.2 g. (83-91%). Although this product is sufficiently pure for use in the next step of this preparation, the remaining acid may be removed from the anhydride by the following procedure. A slurry of 3.2 g. of phosphorous pentoxide in 31.2 g. of the crude anhydride is stirred at room temperature in a stoppered flask for 18 hours. After the reaction" flask has been fitted with a short-path distilling head, it is heated with an oil bath to distill iD.7 g. of forerun, b.p. 74—81°, followed by 27.9 g. of the pure trifluoromethanesulfonic acid anhydride, b.p. 81-84° (Note 3). 

Stick a pin through a match close to the head. Turn off the gas and hang the match head upwards in the tube of the burner by means of the pin. Turn the gas on fully and light it. (4) What happened to the match (5) What does this prove about the temperature of this part of the flame ... 

Cold reheat gas (sulfur recovery), 116 Combination head, 63 Combination tower, 35, 38, 71,83-89 bottoms screen, 35, 38 overhead condenser, 82 delayed coking process, 83-89 explosion-proof trays, 84-85 energy savings, 85-86 coke drum cycles, 86-89 coke drum yields, 88-89 Combustion air supply (process heaters), 317—325 trimming burner operation, 318 excess air benefits, 318 optimizing heater draft, 318— 321 insufficient air, 321-322 optimizing excess air, 322-325 Combustion chamber, 315 Composition instability (distillation tower), 381-382 temperature controller, 381-382 condensing capacity, 382... 

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