Furnace steam boiler

The principal sources of utility waste are associated with hot utilities (including cogeneration) and cold utilities. Furnaces, steam boilers, gas turbines, and diesel engines all produce waste as gaseous c bustion products. These combustion products contain carbon... 

Reducing products of combustion from furnaces, steam boilers, and gas turbines by making the process more energy efficient through improved heat recovery. 

Combustion air can be preheated either with flue gas, lp-steam, quench water, quench oil, or any other available waste heat stream. Air preheating is used in many industrial furnaces (such as reformers, refinery furnaces, steam boilers, etc.) but only in a very few cracking furnaces. The reason is the increased investment costs because of the large number of individual burners in cracking furnaces. 

The main individual sources of noise in chemical and petrochemical plants are burners (process furnaces, steam boilers, and flares), fans, compressors, blowers, pumps, electric motors, steam turbines, gears, valves, exhausts to open air, conveyors and silos, airborne splash noise from cooling towers, coal mills, and loading and unloading of raw and finished materials. 

Energy efficiency of the process. If the process requires a furnace or steam boiler to provide a hot utility, then any excessive use of the hot utility will produce excessive utility waste through excessive generation of CO2, NO, SO, particulates, etc. Improved heat recovery will reduce the overall demand for utilities and hence reduce utility waste. 

Fuel switch. The choice of fuel used in furnaces and steam boilers has a major effect on the gaseous utility waste from products of combustion. For example, a switch from coal to natural gas in a steam boiler can lead to a reduction in carbon dioxide emissions of typically 40 percent for the same heat released. This results from the lower carbon content of natural gas. In addition, it is likely that a switch from coal to natural gas also will lead to a considerable reduction in both SO, and NO, emissions, as we shall discuss later. 

Gas or oil fuel is burned in a furnace or boiler (heat exchanger) to heat air or water, or to make steam that carries the heat absorbed from the combustion process to the rooms in the house, as shovra in Figure 2. This IS accomplished by circulating the warm air through ducts directly to the rooms, or by circulating hot water or steam through pipes to baseboard hot water con-... 

While boiler explosions fortunately do not occur too often today because of the existence of extensive safety devices as well as the regular program of inspection, their effects can be catastrophic. Similarly, sudden and unforeseen damage caused by the overheating of multi-tubular steam boilers due to lack of water can lead to eventual furnace collapse, with very extensive repair costs as well as lost production. 

A boiler bank is also included. The boiler-bank tube bundle provides sufficient heat transfer surface area to provide the rated capacity for saturated steam. Boiler-bank tube spacing and dimensions are arranged so that a steam-water circulation subsystem connects the top and bottom drums with subcooled water passing down the tubes farthest from the furnace and returning as a steam-water mixture. 

Any of a number of steel tubes used simultaneously as heat transfer devices for both steam generation and boiler furnace cooling. Boiler tubes may be straight or bent. 

In such cases, radiant heat transfer is used from the combustion of fuel in a fired heater ox furnace. Sometimes the function is to purely provide heat sometimes the fired heater is also a reactor and provides heat of reaction. The special case of steam generation in a fired heater (a steam boiler) will be dealt with in Chapter 23. Fired heater designs vary according to the function, heating duty, type of fuel and the method of introducing combustion air. However, process furnaces have a number of features in common. A simple design is illustrated in Figure 15.19. The chamber where combustion takes place, the radiant section... 

Energy efficiency of the process. If the process requires a furnace or steam boiler to provide hot utility, then any... 

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 (discussed in Sec. 11), steam boilers, fired heaters, muffle furnaces, and melting pots. Steam boilers have been treated earlier in this section, and a subsequent subsection on industrial furnaces will include muffle furnaces. 

Aside from coal-powered steam locomotives and seagoing ships, which essentially were retired from most regions of the world over the past several decades, solid coal is quite unsuited for transportation energy. The energy density of raw coal means that a significant portion of the energy obtained from combusting it is required to move it (as part of a transportation vehicle). This is further amplified by the equipment required to hum coal—massive, heavy furnaces and boilers—which also have to he moved with the vehicle. 

A coal has the following ultimate analysis C = 0.8339, H2 = 0.0456, 02 = 0.0505, N2 = 0.0103, S = 0.0064, ash = 0.0533, total = 1.000. This coal is burned in a steam-boiler furnace. Determine the weight of air required for theoretically perfect combustion, the weight of gas formed per pound of coal burned, and the volume of flue gas at the boiler exit temperature of 600° F (589 K) per pound of coal burned the air required with 20 percent excess air and the volume of gas formed with this excess and the C02 percentage in the flue gas on a dry and wet basis. 

General References Baukal, C. E., ed., The John Zink Combustion Handbook, CRC Press, Boca Raton, Fla., 2001. Blokh, A. G., Heat Transfer in Steam Boiler Furnaces, 3d ed., Taylor Francis, New York, 1987. Brewster, M. Quinn, Thermal Radiation Heat Transfer and Properties, Wiley, New York, 1992. Goody, R. M., and Y. L. Yung, Atmospheric Radiation—Theoretical Basis, 2d ed., Oxford University Press, 1995. Hottel, H. C., and A. F. Sarofim, Radiative Transfer, McGraw-Hill, New York, 1967. Modest, Michael F., Radiative Heat Transfer, 2d ed., Academic Press, New York, 2003. Noble, James J., The Zone... 

Method Explicit Matrix Relations for Total Exchange Areas, Int.J. Heat Mass Transfer, 18, 261-269 (1975). Rhine, J. M., and R. J. Tucker, Modeling of Gas-Fired Furnaces and Boilers, British Gas Association with McGraw-Hill, 1991. Siegel, Robert, and John R. Howell, Thermal Radiative Heat Transfer, 4th ed., Taylor Francis, New York, 2001. Sparrow, E. M., and R. D. Cess, Radiation Heat Transfer, 3d ed., Taylor Francis, New York, 1988. Stultz, S. C., and J. B. Kitto, Steam Its Generation and Use, 40th ed., Babcock and Wilcox, Barkerton, Ohio, 1992. 

Figure 2.11 show s a highly simpUhed flow sheet of such a fecility for the case of naphtha feedstock. It features a number of furnaces, quench boilers, and a highly complex fractionation train. The hydrocarbon feedstock enters the hot section of the unit through the convection zone of the furnace, where it is preheated (part 11 and is then mixed with steam that is also preheated in this zone. The hydrocarbons and water pass through the radiation zone of the furnace (part 2k w here the rapid temperature rise and pyrolysis reactions take place. At the furnace exit, in order to avoid any subsequent reaction, the... 

Fire 1.4. Steam boiler and furnace arrangements. [Steam, Babcock and Wilcox, Barberton, OH, 1972, pp. 3.14, 12.2 (Fig. 2), and 25.7 (Fig. 5)]. (a) Natural circulation of water in a two-drum boiler. Upper drum is for steam disengagement the lower one for accumulation and eventual blowdown of sediment, (b) A two-drum boiler. Preheat tubes along the Roor and walls are cormected to heaters that feed into the upper drum, (c) Cross section of a Stirling-type steam boiler with provisions for superheating, air preheating, and flue gas economizing for maximum production of 550,000 Ib/hr of steam at 1575 psia and 900°F. 

We fitted it [the laboratory] up with a steam boiler in the cellar, jacketed copper pans, stiUs, a press, and in fact all the equipment of a pharmaceutical laboratory as known at the time. Numbers of open furnaces for divers operations were around, and there were drying rooms on the second floor. 

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