Gas-burner

Flue gas recirculation Flue gas recirculation, alone or in combination with other modifications, can significantly reduce thermal NO. Recirculated flue gas is a diluent that reduces flame temperatures. External and internal recirculation paths have been applied internal recirculation can be accomplished by jet entrainment using either combustion air or fuel jet energy external recirculation requires a fan or a jet pump (driven by the combustion air). When combined with staged-air or staged-fuel methods, NO emissions from gas-fired burners can be reduced by 50 to 90 percent. In some applications, external flue-gas recirculation can decrease thermal efficiency. Condensation in the recirculation loop can cause operating problems and increase maintenance requirements. 

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Gaseous fuels. Gas burners can be diffusion flame burners or pre-aeraled burners. Diffusion flame burners may be relatively simple, with fuel gas burning at an orifice in the presence of... 

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). 

The furnace and thermostatic mortar. For heating the tube packing, a small electric furnace N has been found to be more satisfactory than a row of gas burners. The type used consists of a silica tube (I s cm. in diameter and 25 cm. long) wound with nichrome wire and contained in an asbestos cylinder, the annular space being lagged the ends of the asbestos cylinder being closed by asbestos semi-circles built round the porcelain furnace tube. The furnace is controlled by a Simmerstat that has been calibrated at 680 against a bimetal pyrometer, and the furnace temperature is checked by this method from time to time. The furnace is equipped with a small steel bar attached to the asbestos and is thus mounted on an ordinary laboratory stand the Simmerstat may then be placed immediately underneath it on the baseplate of this stand, or alternatively the furnace may be built on to the top of the Simmerstat box. 

Burning reagents. Turn out all gas burners and switch off all electric hot plates in the vicinity remove everything which may ignite. The control of the fire depends upon its size and kind. 

Tunnel Test. The tunnel test is widely used to test the flame spread potential of building products such as electrical cable (15) and wall coverings (16). The test apparatus consists of a tunnel 7.62 x 0.445 m x 0.305 m ia cross section, one end of which contains two gas burners. The total heat suppHed by the burners is 5.3 MJ/min. The test specimen (7.62 m x 50.8 cm), attached to the ceiling, is exposed to the gas flames for 10 minutes while the maximum flame spread, temperature, and smoke evolved are measured. The use of this and other flame spread test methods has been reviewed (17). 

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... 

Gas burner technology has been developed that permits natural gas to be used effectively as a primary fuel ia both small and large appHcations. 

Fig. 2. Gas-fired denitration pots for denitration of U02(N02)2 6H20. (a) The large pot (1.68 M ID, 0.81 m height) is heated by three concentric rings of small radiant gas burners, (b) The small pot (76 cm ID, 46 cm height) is heated by four gas burners iaside a ceramic furnace (40).

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)... 

Because indirect-heat calciners frequently require close-fitting gas seals, it is customaiy to support aU parts on a selFcontained frame, for sizes up to approximately 2 m in diameter. The furnace can employ elec tric heating elements or oil and/or gas burners as the heat source for the process. The hardware would be zoned down the length of the furnace to match the heat requirements of the process. Process control is normaUy by shell temperature, measured by thermocouples or radiation pyrometers. When a special gas atmosphere must be maintained inside the cyhnder, positive rotaiy gas se s, with one or more pressurized and purged annular chambers, are employed. The diaphragm-type seal ABB Raymond (Bartlett-Snow TM) is suitable for pressures up to 5 cm of water, with no detectable leakage. 

GRAVEL-PACKED GAS WELL vented TO THE atmosphere OR BURNED IN GAS BURNER... 

Vlanv oil biirnor.s arc do.SLgnod a.s cornbination ga.s/oil biirnor.s, An example of a modern low-N(), oil/ga.s forced-draft burner Ls. shown in Fig, 27-30, This is an air-staged design, with the air divided into pri-rnaiv, secondarv, and tertiarv streams. An air-staged natural draft process heater oil/gas burner is illustrated in Fig, 27-3L... 

Gas Burners Gas burners may be classified as premixed or non-premixed. Many types of flame stabilizer are employed in gas burners (see Fig. 27-32). Bluff body, swirl, and combinations thereof are the predominant stabilization mechanisms. 

Nozzle-Mix Burners The most widely used industrial gas burners are of the nozzle-mix type. The air and fuel gas are separated until they are rapidly mixed and reacted after leaving the ports. Figure 27-32c, d, e,f, h shows some examples of the variety of nozzle-mix designs in use. These burners allow a wide range of fuel-air ratios, a wide vari-... 

Staged Burners As was pointed out earher under ToUutant Formation and Control in Flames, the proper staging of fuel or air in the combustion process is one technique for minimizing NO emissions. Gas burners that achieve such staging are available. 

They include the combustion chamber, gas burners, burner controls, and exit temperature indicator. Usual exit temperatures for the destruction of most organic materials are in the range of 650°-825°C, with retention times at the elevated temperature of 0.3-0.5 sec. 

A drying oven whieh is eonstrueted of firebriek walls is heated by an eleetrieally operated gas burner as shown in Figure 2.22. The system variables and eonstants are... 

Gas burner This converts gas flow-rate v t) into heat flow Q[ t) i.e. ... 

AMD 2 Automatic shut-off valves for gas burners and gas appliances (AMD 9796J dated... 

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. 

The CHP plant which replaced these two separate energy supplies is based on a Ruston TB gas turbine (rated at 3.65 MW) which can meet the electrical demand of 3.2 MW and is connected to the grid so that excess electrical power can be sold. By providing full gas power, up to 12 t/h of saturated steam can be produced at 191°C and 13 bar. Five supplementary gas burners can be engaged to increase the steam... 

Strumpf, m. stocking, hose mantle (of a gas burner), -band, n. garter, -waren, f.pl. hosiery. 

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