Burner

The burners should not be installed too close to the tubes. Depending on the burner size, 3 to 5 feet should be provided between the centers of burners and tubes on the same wall. If burners are placed on the end walls, they should be 5 feet from the side walls. 

Fuel oil must be atomized to bum. Steam in the burner tip may be used or the oil can be brought in at hi pressures to furnish the energy for atomization by so-called mechanical burners. 

A gas burner may have a central tip that is interchangeable with an oil burner or it may have a ring with numerous holes surrounding the burner refractory orifice. The latter type is often used for combination oil and gas burners. 

If there is an air preheater, the combustion air will be brought in through an insulated duct to avoid heat loss and to protect the operators. It is important tiiat such ducts be provided with expansion bellows and that the duct be properly tapered to insure an even supply of air to each burner. 

The lane spacing between tube rows must be sufficient to avoid flame impingement from the burners. Typical spacing ranges from 6 to 8 feet. 

The burners are located between the tube rows. Increasing the number of burners reduces the heat release per burner, which permits a smaller flame diameter and reduced lane spacing. The number of burners varies with the design, but a ratio of one burner for every 2 to 2.5 tubes will provide a very uniform heat release pattern and is considered good design practice. 

For most hydrogen plants, the burners are a dual-fired design, which will fire both PSA offgas and the supplemental makeup gas. Lo-NOx burners are typically used to meet modem environmental requirements. In some burner designs, the makeup gas is used to induce flue gas into the flame, thereby reducing the flame temperature and the NOx level. With a properly designed burner, NOx levels of as low as 0.025 Ibs/MM Btu LHV of heat release can be expected. 

Peep doors Small doors are provided in the wall or floor of the radiant section to permit visual inspection 3f burners during start-up or operation. 

Pigtails Small-bore flexible piping configurations onnect the radiant tubes to the inlet and outlet head- rs, as illustrated in Exhibit 7-6. 

Lefractory The refractory is made up of insulating iricks capable of withstanding high temperatures in rrnaces. 

Snuiifing steam This is steam that is injected into the combustion chambers or header box of a furnace to suppress a fire. 

Transfer line The outlet of the process tubes are tied into a piping header called a transfer line, which feeds the main process tower. 

Afterburner chambers should be of welded steel construction with an internal refractory lining, or constructed of steel that can withstand the conditions of operating temperatures and the corrosiveness of the off-gas. 

Afterburner chambers should be equipped with sight glasses, inspection hatches, connections for measurement devices and a fly ash discharge. 

Burners are intended either for warming up the system and waste ignition in the startup phase, or for auxiliary firing during operation to maintain the desired operating temperatures. The burners and their control system shall meet the aj lic-able regulations of the competent authority. Special burners for contaminated oils, solvents or aqueous mixtures may also be required. 

---

Liquid fuels. Industrial burners for liquid fuels usually atomize the fuels in hot air so that droplets will evaporate during combustion. For more volatile fuels such as kerosine, vaporizing burners of various types are employed, usually for domestic purposes. 

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... 

Among the various detectors specific for nitrogen, the NPD (Nitrogen Phosphorus Thermionic Detector) we will consider, is based on the following concept the eluted components enter a conventional FID burner whose air and hydrogen flows are controlled to eliminate the response for hydrocarbons. 

Thus, according to the definitions, diesel fuel (or gas oil) is not a heating fuel but a motor fuel. Incidentally, heavy fuel can be considered a heating fuel or a motor fuel depending on its application in a burner or in a marine diesel engine. 

It is useful to specify at the start the principal quality criteria for each type of product (motor fuels, heating fuels), imposed by the requirements for the different kinds of energy converters motors, turbines, burners. 

In a general manner, diesel engines, jet engines, and domestic or industrial burners operate with lean mixtures and their performance is relatively insensitive to the equivalence ratio. On the other hand, gasoline engines require a fuel-air ratio close to the stoichiometric. Indeed, a too-rich mixture leads to an excessive exhaust pollution from CO emissions and unburned hydrocarbons whereas a too-lean mixture produces unstable combustion (reduced driveability and misfiring). 

For other physical properties, the specification differences between diesel fuel and home-heating oil are minimal. Note only that there is no minimum distillation end point for heating oil, undoubtedly because tbe problem of particulate emissions is much less critical in domestic burners than in an engine. 

In 1993, French consumption of these products was around 6 Mt and 2.5 Mt respectively for use in burners and in diesel engines. The latter figure appears in the statistics under the heading, marine bunker fuel . Its consumption been relatively stable for several years, whereas heavy industrial fuel use has diminished considerably owing to the development of nuclear energy. However, it seems that heavy fuel consumption has reached a bottom limit in areas where it is difficult to replace, e.g., cement plants. 

The heavy fuel should be heated systematically before use to improve its operation and atomization in the burner. The change in kinematic viscosity with temperature is indispensable information for calculating pressure drop and setting tbe preheating temperature. Table 5.20 gives examples of viscosity required for burners as a function of their technical design. 

The Conradson Carbon of a heavy fuel can often reach 5 to 10%, sometimes even 20%. It is responsible for the combustion quality, mainly in rotating tip atomizing burners. 

The properties linked to storage and distribution do not directly affect the performance of engines and burners, but they are important in avoiding upstream incidents that could sometimes be very serious. We will examine in turn the problems specific to gasoline, diesel fuel, jet fuel and heavy fuel. 

This justifies all the work undertaken to arrive at fuel denitrification which, as is well known, is difficult and costly. Moreover, technological improvements can bring considerable progress to this field. That is the case with low NO burners developed at IFF. These consist of producing separated flame jets that enable lower combustion temperatures, local oxygen concentrations to be less high and a lowered fuel s nitrogen contribution to NOj. formation. In a well defined industrial installation, the burner said to be of the low NO type can attain a level of 350 mg/Nm, instead of the 600 mg/Nm with a conventional burner. 

The major portion of sait is found in residues as these streams serve as the bases for fuels, or as feeds for asphalt and petroleum coke production, the presence of salt in these products causes fouling of burners, the alteration of asphalt emulsions, and the deterioration of coke quality. Furthermore, calcium and magnesium chlorides begin to hydrolyze at 120°C. This hydrolysis occurs rapidly as the temperature increases (Figure 8.1) according to the reaction i. ... 

Total sulfur NF EN 24260 ISO 4260 ASTM D 2785 Combustion in Wickbold burner and analysis... 

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 A3.14.14. A cellular flame in butane oxidation on a burner. (Courtesy of A C McIntosh.)...

The material to be steam-distilled (mixed with some water if a solid compound, but not otherwise) is placed in C, and a vigorous current of steam blown in from D. The mixture in C is thus rapidly heated, and the vapour of the organic compound mixed with steam passes over and is condensed in E. For distillations on a small scale it is not necessary to heat C if, however, the flask C contains a large volume of material or material which requires prolonged distillation, it should be heated by a Bunsen burner, otherwise the steady condensation of steam in C will produce too great a volume of liquid. 

The mixture to be separated is dissolved in a suitable solvent and spotted on to a pencilled line at the bottom of the t.l.c. plate, ca. i o-i 5 cm. from the end. A suitable dropping tube may he made by drawing out the middle of a m.p. tube with a micro-burner and breaking the tube in the middle. The dropper is filled by capillary action and is discharged when the liquid at the tip drops on to the untouched absorbent surface the spot should be 2 5 mm. in diameter. 

A skilled worker can use a micro-Bunsen burner for most types of heating. Nevertheless, as there is a tendency for a liquid to shoot out of a small test tube when heated, it is preferable to place the tube in a hot water-bath or in a metal heating block. A small glycerol bath is suitable for distillations and heating under reflux, the glycerol being subsequently easily removed from flasks, etc., by washing with water. 

Hold the tube horizontally and quickly seal this end in a micro-burner. Attach the tube (with the open end upwards) to a thermometer in the melting-point apparatus (Fig. i(c), p. 3) so that the trapped bubble of air in the capillary tube is below the surface of the bath-liquid. Now heat the bath, and take as the b.p. of the liquid that temperature at which the upper level of the bubble reaches the level of the surface of the batn liquid. 

The heating of the vessels is accomplished by means of a small bath or a micro-Bunsen burner. The vessel can be clamped at such a distance from the burner that the contained liquid boils gently under reflux. Smooth boiling is ensured by the addition of 1-2 minute pieces of unglazed porcelain, or of a short piece of melting-point tubing open at both ends. 

If the solid does not dissolve in the cold solvent gently heat the mixture over a micro-Bunsen burner or in a small water-ba until the liquid boils. Continue to add o-i ml. portions of solvent until the solid dissolves. [If more than about i ml. of solvent is required, the solvent is considered unsatisfactory.] If a clear solution is obtained, cool the tube and scratch it below the surface of the solution with a very fine glass rod and proceed as suggested on p. 16. In general, the products from the choice of solvent investigation are not discarded but added to the main bulk of the crude product for recrystallisation. 

The liquid becomes progressively darker in colour, and then effervesces gently as ethylene is evolved. Allow the gas to escape from the delivery-tube in T for several minutes in order to sweep out the air in F and B. Now fill a test-tube with water, close it with the finger, and invert the tube in the water in T over the delivery-tube so that a sample of the gas collects in the tube. Close the tube again with the finger, and then light the gas at a Bunsen burner at a safe distance from the apparatus. If the tube contains pure ethylene, the latter burns with a clear pale blue (almost invisible) flame if the ethylene still contains air, the mixture in the test-tube ignites with a sharp report. Allow the... 

When the reaction is complete, heat the stirred mixture carefully under reflux over a Bunsen burner and asbestos gauze for I hour if the mixture becomes too thick for efficient stirring, add up to 15 mL of acetic acid. Now decant the hot mixture into 500 ml. of vigorously-stirred ice-cold water wash the residual zinc thoroughly with glacial acetic acid (2 portions each of I -2 ml.), decanting the acid also into the stirred water. 

---