Flame-out

Measured in MJ/m or Btu/ft, the Wobbe Index has an advantage over the calorific value of a gas (the heating value per unit volume or weight), which varies with the density of the gas. The Wobbe Index Is commonly specified in gas contracts as a guarantee of product quality. A customer usually requires a product whose Wobbe Index lies within a narrow range, since a burner will need adjustment to a different fuel air ratio if the fuel quality varies significantly. A sudden increase in heating value of the feed can cause a flame-out. 

When a customer agrees to purchase gas, product quality is specified in terms of the calorific value of the gas, measured by the Wobbe index (calorific value divided by density), the hydrocarbon dew point and the water dew point, and the fraction of other gases such as Nj, COj, HjS. The Wobbe index specification ensures that the gas the customer receives has a predictable calorific value and hence predictable burning characteristics. If the gas becomes lean, less energy is released, and if the gas becomes too rich there is a risk that the gas burners flame out . Water and hydrocarbon dew points (the pressure and temperature at which liquids start to drop out of the gas) are specified to ensure that over the range of temperature and pressure at which the gas is handled by the customer, no liquids will drop out (these could cause possible corrosion and/or hydrate formation). 

Figure 10-24 shows a schematic of an actual dry low emission NO combustor used by ALSTOM in their large turbines. With the flame temperature being much closer to the lean limit than in a conventional combustion system, some action has to be taken when the engine load is reduced to prevent flame out. If no action were taken flame-out would occur since the mixture strength would become too lean to burn. 

The compressor of a gas turbine is one of the most important components of the gas turbine. It consumes between 50-65% of the energy produced in a gas turbine. Thus fouling of the compressor can cause large losses in power and efficiency for the gas turbine. Furthermore, the fouling of the compressor also creates surge problems, which not only affects the performance of the compressor but also creates bearing problems and flame-outs. The following are some of the major characteristics that need to be calculated ... 

Smokeless operation can generally be achieved, with essentially no noise or luminosity problems, provided that the design gas rate to the flare is not exceeded. However, since the flame is near ground level, dispersion of stack releases is poor and this may result in severe air pollution or hazard if the combustion products are toxic or in the event of flame-out. Capital and operating cost and maintenance requirements are high. 

All flares must be provided with continuous pilots to ensure combustion of any releases discharged to them, and to prevent flame-out from occuring. Various designs of pilot burner are available, and proprietary tips for elevated flares are normally provided complete with pilots. 

Heaters and furnaces should also be designed in accordance with standards and codes. Boilers and heating units must be inspected periodically in accordance with codes, insurance requirements and state regulations. Proper controls, interlocks and fail-safe instnunentation must be provided. The heaters should also be provided with sight glasses for flame observation, monitoring devices for flame-out detection, and temperature alarms. 

All glassware used in this preparation must be dry. Flaming out while purging with prepuriiied nitrogen is sufficient. 

Monomeric styrene is destabilized as in Example 3-1 and pre-dried with calcium chlo-ride.The monomer is now allowed to stand over calcium hydride for 24 h and then distilled under reduced pressure of nitrogen into a previously flamed-out Schlenk tube. Pure 4-vinylpyridine is distilled twice over KOH pellets in vacuum.lt is then vacuum distilled under nitrogen through a column packed with Raschig rings into a previously flamed out Schlenk tube (bp 62 °C/12 torr).The closed Schlenk tubes containing the monomers are stored in a refrigerator until required.The preparation of the initiator solution (sodium naphthalene) is described in Example 3-19. 

The polymerization is carried out as follows a Schlenk tube that has been flamed out and filled with nitrogen, is charged with 50 ml of pure THE and 1 ml of sodium naph-... 

The simple Vycor reaction tube used for the high-temperature reaction is shown in Fig. 1. It consists of a wide body of 30 mm outside diameter and 100 mm length and of a narrow neck of 9 mm outer diameter and 180 mm length. For handling outside of the drybox, it is equipped with a vacuum hose and a stopcock. Prior to use, it should be flamed out under a dynamic vacuum. To keep the neck of the reaction tube clean, the tube should be filled using a funnel with a narrow neck of 180 mm length. 

Some fired heaters, especially boilers, have a device called a purple peeper, which is simply an optical device that looks at a flame. If it does not detect light with a wavelength in the high-frequency (i.e., purple) end of the optical scale, it interprets this as a flame-out. The fuel-gas regulator is automatically shut. 

Flame Quenching. Quenching at the fringe of a burner flame, with the consequent appearance of a dead space, has already been mentioned. However, there arc also cases in which wall quenching puts the flame out completely. This is generally most notable at reduced pressure. As the pressure is lowered, flame can propagate without difficulty in a channel of given width, until some critical pressure is reached. At lower pressures,... 

Starting of turbojet engines is more difficult at altitudes or at low ambient temperatures on the ground. Altitude ignition is required after flame-outs or with multiengine aircraft where all engines may not be operated at all times. 

Panel before, after, Wt. Loss, Wt. Loss, Char Area, Volume, Face Flame, Flame Out, Flame Out,... 

Mallet et al. [174] used an automated gas chromatographic system which consisted of a gas chromatograph mounted with an automatic sample interfaced to an integrator. A Melpar flame photometric detector (phosphorus mode) was connected with the flame gas inlets in the reverse configuration to prevent solvent flame-out. The detector was... 

Note It is better to blow the flame out, and then turn off the gases than to turn off the gases before the flame is out to reduce the chance of the torch popping. The surface mix torch does not require special shut-off procedures because the surface-mix torch cannot pop. Therefore, it does not make a difference which gas you turn off first. There is also no reason to blow out the flame of a surface-mix torch—besides, you cannot. 

A 1-L, three-necked, round-bottomed flask is equipped with a serum cap, a nitrogen inlet tube connected to a T-piece that leads to a prepurified nitrogen supply and to a Nujol bubbler, and a solids-transfer tube (in the center neck). The flask is evacuated, flamed out, and flushed with dry nitrogen. It then is charged with octacarbonyldicobalt (73.4 g, 0.215 mole) and 440 mL of dry tetrahydrofuran (THF). The transfer tube is removed and replaced with an... 

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