Fired heaters flames

Indirect-Fired Equipment (Fired Heaters) Indirect-fired combustion equipment (fired heaters) transfers heat across either a metallic or refractory wall separating the flame and products of combustion from the process stream. Examples are heat exchangers (dis-... 

The tubes that are around the flame get most of their heat energs t rom radiation. The tubes in the top of the chamber get their heat from com ec-tion as the hot exhaust gases rise up through the heater and heat ihc process fluid in the tubes. The principal classification of fired heaters relates to the orientation of the heating coil in the radiant section. The tube coils of vertical fired heaters are placed vertically along the walls of the combustion chamber. Firing also occurs vertically from the Hoor of the heater. All the tubes are subjected to radiant energy. 

Modem fired heaters operate at thermal efficiencies of between 80 to 90 per cent, depending on the fuel and the excess air requirement. In some applications additional excess air may be used to reduce the flame temperature, to avoid overheating of the tubes. 

Provisions should be made to direct flammable or combustible liquid spills away from fired heaters. Spills from other equipment that flow into or under fired heaters can and have been ignited by the hot surfaces or flames of fired heaters. Conversely, in the past, spills from ruptured tubes in process heaters have allowed burning liquid to flow around and damage other equipment. Both process heaters and nearby equipment should be protected from each other due to possible spills of flammable or combustible liquids using one of the following methods ... 

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. 

Within 20 to 35 minutes after the heater was fired, a fire-water sprinkler system tripped. A heater flame failure alarm occurred a short time later. Witnesses stated flames were over 50 ft. (15 m) high in approximately five seconds after the tube ruptured. The fire damages... 

Class 1 safety instrumentation loops include alarms and trips on storage tanks containing flammable or toxic liquids, devices to control high temperature and high pressure on exothermic-reaction vessels, and control mechanisms for low-flow, high-temperature fluids on fired heaters. Other Class 1 instruments include alarms that warn of flame failure on fired heaters, and vapor detectors for emergency valve isolation and sprinkler-system activation. All of these alarms, shutdown valves, and other critical instruments are regularly proof-tested to a well-defined schedule. 

FIG. 19-13 Noncatalytic gas-phase reactions, (a) Steam cracking of light hydrocarbons in a tubular fired heater, (b) Pebble heater for the fixation of nitrogen from air. (c) Flame reactor for the production of acetylene from hydrocarbon gases or naphthas. [Patton, Grubb, and Stephenson, Pet. Ref. 37(11) 180 (1958).] d Flame reactor for acetylene from light hydrocarbons (BASF), (e) Temperature profiles in a flame reactor for acetylene (Ullmann Encyclopadie der Technischen Chemie, vol. 3, Verlag Chemie, 1973, p. 335). 

Reactors, chemical, 567-582 classification, 568 ebbulating bed. 593 fermentacon, 654,659,660 fired heater, 574,575 fixed bed, 572 flame, 573... 

R. Samson, F. Goudna, O Maaskant, T. Gilmore, The design and installation of a low-temperature catalytic NO, reduction system for fired heaters and boilers. Proceedings Fall International Symposium of the American Flame Research Committee, San Francisco, Calif., October 8-10, 1990. 

Crude-oil heaters, also called fired heaters, heaf crude oil to begin fhe process for refining. Open flames in a chamber heaf thick oil in boiler tubes to strip off lighter hydrocarbons in the separation process before other processing takes place [5]. 

Operators use furnace cameras to remotely view burners in the numerous fired heaters that are heating this oil to spot such performance defecfs as flame impingement, flames that are burning too low, clogged burners, irregular flame patterns, flashback, flames thaf are producing too much pollution, or oil spillage. 

Camera approach Visually observe the waterwall or refractory wall directly to be certain flames are not touching the walls, causing potentially catastrophic leaks at sites like crude oil (fired) heaters. Besides spotting flames contacting the external tube surface inside the firebox, the camera can also spot other signs of impingement like tubes with a cherry-red color or bulges in the tube walls [12]. 

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