Pilot flames

In any gas burner some mechanism or device (flame holder or pilot) must be provided to stabilize the flame against the flow of the unbumed mixture. This device should fix the position of the flame at the burner port. Although gas burners vary greatly in form and complexity, the distribution mechanisms in most cases are fundamentally the same. By keeping the linear velocity of a small fraction of the mixture flow equal to or less than the burning velocity, a steady flame is formed. From this pilot flame, the main flame spreads to consume the main gas flow at a much higher velocity. The area of the steady flame is related to the volumetric flow rate of the mixture by equation 18 (81,82)... 

Each pilot burner shall be equipped with a chrome/alumel thermocouple or similar device to sense the stams of the pilot flame. 

Lockerstelle, /. (Cryat.) loose place, loose spot. Lockerung, /. loosem ng disintegration. Lockflamme,/. pilot flame. 

Spar-flammehen, n., -flamme, /. pilot flame. Spargel, m. asparagus, -stein, m. asparagus stone (variety of apatite), -stoff, m. asparagine. 

Flares are an attempt to deliberately burn the flammable safety relief and/or process vents from a plant. The height of the stack is important to the safety of the surroundings and personnel, and the diameter is important to provide sufficient flow velocity to allow the vapors/ gases to leave the top of the stack at sufficient velocities to pro ide good mixing and dilution after ignition at the flare tip by pilot flames. 

Non-aerated 0.01kW-50kW No N gas, LP gas 5mbar-75mbar <2 1 Semi-luminous lambent, low intensity Pilot flame and domestic apphcations... 

Chemiluminescence images of a turbulent partially premixed CH4/ air jet flame stabilized by premixed pilot flames. 

For the quantification of fire propagation behavior of the FRC materials, 0.10 m wide and 0.61 m long vertical sheets with thickness varying from 3 mm to 5 mm were used. The bottom 0.15 m of the sheet was exposed to 50 kW/m2 of external heat flux in the presence of a 0.01 m long pilot flame to initiate fire propagation. For the simulation of large-scale flame radiation, experiments were performed in k0% oxygen concentration. 

The processes described by Equation (7.3) are complex and require an elaborate analysis to make precise determinations of flg. By making appropriate estimates of each of the time components, we can considerably simplify practical ignition analyses for most typical fire applications. Again, we are just considering piloted-flaming ignition but autoignition can be similarly described. 

If the incident heat flux is 10 kW/m2, how long will it take the kerosene to ignite with a pilot flame present ... 

The main components of an elevated flare system are the flare burner with or without smoke suppression capability, pilot(s), pilot igniter(s), support structure, and piping. A number of optional features are available, such as pilot flame detectors air seals (buoyancy or... 

Pilot Flame — A pilot flame shall be provided for automatic relighting of the exposure flame. A bead 4mm (5/32 inch) in diam may be mounted on the lid so that the size... 

With convective heating of wood under laboratory conditions, spontaneous ignition is reported as low as 270°C and as high as 470°C (5,14,15). Spontaneous ignition of wood charcoal, which has excellent absorption of oxygen and radiant heat, occurs between 150°C and 250°C (5). In one experiment on ignition, oven-dried sticks of nine different species were ignited by pilot flame in 14.3 to 40 minutes when held at 180°C, in 4 to 9.5 minutes when held at 250°C and in 0.3 to 0.5 minutes when held at 430°C (16). 

In the ASTM E84 25-foot tunnel furnace test (34) for measuring flame spread of building materials, an igniting pilot flame is applied to the underside of a horizontally mounted specimen. The flame heats the combustible material to pyrolysis, and the flammable gases given off are ignited by the pilot flame. 

The process via which a flame is started is called ignition. There are two types of ignition for gaseous mixtures induced ignition via a hot spot, spark, or a small pilot flame, and... 

A pilot flame, spark plug, or hot wire is often used to ignite the gases and vapors that are generated by the pyrolysis of the heated specimen. When a pilot flame is used, it is either located in the gas phase or impinging on the specimen surface. The latter is less desirable because it locally increases the heat flux to the specimen by an unknown amount. 

In flame spread tests, the specimen is ignited at the hot end by a nonimpinging premixed acetylene-air pilot flame. Flame spread rate over the surface is then monitored as a function of distance x. Thus, one experiment yields information on flame spread rate over a whole range of heat flux levels (or surface temperatures). Information to this extent can be obtained in one run owing to the particular shape of the flux invariant, which is the result of the specific geometry and specimen-panel arrangement shown in Figure 14.7. 

Conceptually, there are two types of flame spread tests. The length of the specimen is generally much greater than the width and flame propagation is measured in the direction of the longest dimension. In the first type of flame spread tests, the specimen is exposed to a gas burner flame at one end. In the second type, the specimen is exposed to a radiant panel producing a heat flux that varies from one end of the specimen to the other. A pilot flame is used to ignite the specimen at the hot end. An example of each of the two types is described as follows. 

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