Example

Given In addition to the measurements from the previous example, the measured wet 02 in the stack is 4 . Find The estimated exhaust gas flow rate in both scfh and acfh. Solution Based on the measured fuel and air measurements and assuming no air leakage into the furnace, then the calculated wet O2 would be 4l50 scfh l25,000 scfh 3.32 (since the measured wet 02 is 4 then there must be air infiltration) l0,000CH4 + x (0.2l02 + 0.79N2) l0,000C02 + 20,000H20 + (0.2lx - 20,000)02 + 0.79xN2 4 0.04...

163 Variable Emission Regulations

Many approaches are being used to address the dynamic nature of pollutionemission regulations. The most common approach is simply to continue to rewrite the regulations as new technologies are developed to reduce emissions significantly compared to previous technologies. This process to rewrite the regulations can be expensive, tedious, lengthy, and fraught with problems. Regulators work in conjunction with users to determine what new levels make sense in the light of economics and technology....

11263 Combustion Modification

A major objective in combustion modification is to increase the overall thermal efficiency so that less fuel will need to be burned for a given level of production. Reducing fuel consumption simultaneously reduces CO2 emissions. The U.S. Department of Energy has funded major research projects designed to mitigate CO2 generation by combustion modification processes 24 . Most of the research is targeted at power generation, which produce the largest portion of CO2 emissions. One common method for...

11221 Fuel Composition and Temperature

There are many factors that affect the amount of CO2 produced during the combustion of fossil fuels in industrial processes. The global simplified reaction of a hydrocarbon with air can be written as follows CxHy + a(O2 + 3.76N2) xCO2 + 0.5yH2O + bO2 + 3.76aN2 + minor species where x and y are determined by the fuel, and the minimum a for complete combustion can be calculated from an O atom balance where b 0 In reality, there will be some excess O2 (b > 0) to ensure complete combustion. For...

1842 Combustion Modification

EPA has sponsored much research on reducing NOx 20 and SOx 21 emissions, which has led to a number of combustion modification technologies that have been applied in industry. One example of a new yet-to-be commercialized research and development project is a demonstration of the use of pulse combustion in waste incineration to reduce pollutant emissions 22 . The technology was applied in the Environmental Protection Agency's Incineration Research Facility rotary kiln system. The...

13311 Furnaces Used in Aluminum Melting

The general method for secondary aluminum production includes the following processes charging, melting, fluxing, demagging, degassing, alloying, skimming, and pouring. Charging involves adding pretreated scrap (to remove impurities, shredding, etc.) and flux to a small pool (referred to as a heel) of molten aluminum left behind from the previous heat. The flux materials combine with contaminants and cause them to float so that they can be easily skimmed off and removed. The materials floating...

1989

A spectral line-based weighted-sum-of-gray-gases model for arbitrary RTE solvers. J. Heat Transfer, Vol. 115, pp. 1004-1012, 1993. RG Siddall, N Selcuk. The Application of Flux Methods to Prediction of the Behavior of a Process Gas Heater. In Heat Transfer in Flames, ed. NH Afgan, JM Beer. Washington, DC Scripta Book Company, Chap. 11, pp. 191-200, 1974. LD Cloutman, L Brookshaw. Numerical Simulation of Radiative Heat Loss in an Experimental Burner. Lawrence Livermore...

1323 Ladle Preheating

Another major use for burners in the steel industry's melt shops is for ladle preheating, as shown schematically in Fig. 13.11 22 . Figure 13.12 23 shows a ladle that is used to transport molten metal in steel mills from the melting furnace to the casting station. Figure 13.13 shows a photograph of a ladle preheater in use. Ladles are refractory-lined cylindrical vessels closed at one end. The molten metal is poured into the top and then the ladle is usually transported via an overhead crane...

References

Heat Transfer in Industrial Combustion. Boca Raton, FL CRC Press, 2000. 2. JL Reese, GL Moilanen, R Borkowicz, C Baukal, D Czerniak, R Batten. State-of-the-art of NOx emission control technology. ASME paper 94-JPGC-EC-15, Proceedings of International Joint Power Generation Conference, Phoenix, AZ, 3-5 Oct. 1994. 3. J McAdams, J Karan, R Witte, M Claxton. Low NOx burner maintenance in high temperature furnaces. Proceedings of the 14th Ethylene Producers' Conference, New York American...

14212 Recuperative Melter

Figure 14.10 shows a schematic of a typical recuperative melter. A recuperative melter is a unit melter equipped with a recuperator. Typically, the recuperator is a metallic shell and tube style heat exchanger that preheats the combustion air to 1000 -1400 F (540 -760 C). The furnace is fired with four to 20 individual burners. These furnaces range in size from as large as 280 tons (250 metric tons) per day of glass to as small as 20 tons (18 metric tons) per day of glass. These furnaces are...

43 Simplified Models

Wilson 90 presents a new and more efficient technique for simulating the first-order dependence of a flame in a furnace. The technique is called the moving-boundary flame model. Dynamic state variables are created to keep track of the size of the flame in the furnace. The technique is claimed to be a considerable improvement over point reactor models, but is not intended to replace detailed multidimensional CFD models. Its accuracy depends on data from either experimental results or from more...

91

AReduction efficiencies for ND or MD SNCR are equal. MD mechanical draft, ND natural draft, LNB low NOx burner, ULNB ultralow NOx burner, SNCR selective noncatalytic reduction, SCR selective catalytic reduction, FCR flue gas recirculation. aReduction efficiencies for ND or MD SNCR are equal. MD mechanical draft, ND natural draft, LNB low NOx burner, ULNB ultralow NOx burner, SNCR selective noncatalytic reduction, SCR selective catalytic reduction, FCR flue gas recirculation. The fourth type of...

2400

0 200 400 600 800 1000 1200 1400 1600 1800 2000 Air Preheat Temperature ( F) Figure 2.30 Adiabatic equilibrium flame temperature vs. air preheat temperature for stoichiometric air H2, air CH4, and air C3H8 flames. (From Ref. 27. Courtesy of CRC Press.) Figure 2.31 Adiabatic equilibrium flame temperature vs. fuel preheat temperature for stoichiometric air H2, air CH4, and air C3H8 flames. (From Ref. 27. Courtesy of CRC Press.) Figure 2.31 Adiabatic equilibrium flame temperature vs. fuel preheat...

1711 Black Liquor Recovery Boilers

A flow schematic of the Kraft process is shown in Fig. 17.7 8 . It produces a strong, dark-colored fiber that is made from wood chips in either a batch or continuous digester, under pressure, in the presence of a cooking liquor 9 . The spent chemicals from the process are called black liquor, which is a highly viscous liquid waste containing inorganic cooking chemicals and organic materials such as lignin, aliphatic acids, and extractives. It is a by-product of the chemical pulping process....

452 Combustor Modeling

Numerous papers have been presented over the past few decades on modeling of industrial combustors. Some of the earliest work was done at Imperial College (U.K.) 2,268,269 . A sampling of references are given for modeling industrial combustors General combustors and boilers 270-285 Pulse combustion system 286-289 Aluminum reverberatory furnaces (see Fig. 4.15) 263,297 Metal reheat furnaces 47,298-302 Radiant tube batch furnace 303 Flash smelting furnaces 304,305 Cokeless natural gas-fired...

114 Dioxins And Furans

This class of pollutants includes the carbon-hydrogen-oxygen-halogen compounds, chemically classified as halogenated aromatic hydrocarbons, and has received considerable attention from both the general public and from regulatory agencies because of the potential health hazards associated with them. Dioxins generally refer to compounds that are structurally and chemically related to chlorinated congeners (members of the same chemical family) Polychlorinated dibenzo-para-dioxins (PCDDs)...

441 Increasing Popularity of CFD

Computational fluid dynamics is a numerical tool for simulating the complicated fluid flow, heat transfer, and chemical reactions in a combustor. This tool has been gaining in popularity in recent years because of a number of factors. One obvious change is the dramatic increase in computer power that is available at a cost that is affordable for virtually all businesses. Each new generation of computer hardware continues to have more speed and more memory at a lower cost. The personal computers...

13312 Oxygen Enhanced Aluminum Production

Conventional practice is to use air fuel burners in these rotary furnaces. The concept of using an oxygen fuel burner within an air fuel burner provides the aluminum melter with the flexibility of using either burner, or a combination of both burners (see Fig. 13.31). This innovative approach has proved to be very successful in the aluminum industry 67 . This differs considerably from both conventional oxygen-enriched techniques and the oxy fuel burners typically used for melting in the metals...

Ch

Figure 12.29 Operating regime for lean premix flames. produces low NOx emissions. Figure 12.32 shows that burner operating in a hot furnace. Figure 12.33 shows that flue furnace gas recirculation reduces NOx in premix flames. Figure 12.34 shows NOx emissions for diffusion and premix flames with and without flue furnace gas recirculation. It also shows one operating scheme where the primary combustion zone is fuel-lean premixed, the secondary zone is fuel-rich premixed, and the overall operation...

Multimode Heat Transfer And Fluid Dynamics

Figure 16.1 Fundamental processes in rotary kiln incinerators. (From Ref. 5. Courtesy of CRC Press.) recycling. For example, plastics, aluminum cans, and glass products may be selectively removed from waste materials so that they can be recycled. This is very beneficial to the incineration process because the aluminum and glass products are an additional heat load and not an additional source of fuel. Plastics can burn but they can also produce some toxic pollutants like dioxins and furans. A...

4232 Simplified Chemistry

The term simplified chemistry is a somewhat relative term, but generally refers to reducing the number of chemical equations used to represent a system, reducing the complexity of the reaction mechanism, or a combination of both. In the first approach, a very limited number of reactions and species are used to represent the actual combustion reaction system, which may involve hundreds of reactions and dozens of species. In this approach, a greatly reduced set of reactions are used 53 . Often...

171 Paper Industry

The paper industry is composed of two primary sectors 3 Pulp and paper mills, which produce mechanical, thermomechanical, and chemical pulps and process these pulps to form paper, paperboard, or building papers. Converting operations, which manufacture boxes, tablets, and other finished paper products. The first sector involves production of paper products from raw wood while the second involves converting those initial products into more specialized end products. The pulp and paper industry...

12215 Swirl Effects

Swirl means that some angular motion is imparted to the flame. This is typically achieved by angling some or all of either the combustion air or the fuel or both with respect to the main axis or normal of the burner. Swirl is often used to intensify mixing, which usually shortens the flame and increases the flame temperatures near the burner. This enhances fuel burnout and reduces or eliminates CO emissions. Swirl is often used in liquid and solid fuel combustion because these fuels are more...

1331 Aluminum Production

Aluminum is one of the most essential materials for U.S. transportation, packaging, and construction industries 49 . Aluminum has some unique properties, which make it particularly valuable including its high strength-to-weight ratio, low maintenance, and ease of recycling. It is used in the transportation industry (automobiles, trucks, rail cars, ships, and commercial aircraft), the packaging industry (aseptic food containers and beverage cans), the construction industry (windows, doors, and...

1333 Lead Production

Lead is made through primary and secondary processes. Since traditional industrial combustion processes are not used in primary processes, only secondary smelting is considered here where recycled metal is used in a smelting furnace. There are three major operations in secondary lead smelting scrap pretreatment, smelting, and refining 89 . Scrap pretreatment includes removal of large contaminants, shredding large pieces, draining fluids, and possibly drying wet materials. Smelting is used to...

1714 Paper Dryers

In many drying processes, moisture is removed from paper webs often traveling at high speeds. Radiant heating (see Fig. 17.9) is often used to supplement steam-heated Figure 17.9 Infrared (IR) burner heating a continuously moving paper web. (From Ref. 16. Courtesy of Marsden, Inc., Pennsauken, NJ.) Figure 17.10 Supplemental IR burners for paper drying located over steam cylinders. (Courtesy of Marsden, Inc., Pennsauken, NJ.) Figure 17.10 Supplemental IR burners for paper drying located over...

125 Health Effects

Ozone, VOCs, nitrogen dioxide, carbon monoxide, particulate matter, sulfur dioxide, and lead are specified as criteria pollutants under the Clean Air Act. Each of these has some detrimental health effects on humans. Ozone, nitrogen dioxide, particulate matter, and sulfur dioxide can cause respiratory problems. These are particularly problematic for those who have lung diseases such as asthma and emphysema. VOCs can cause a variety of health problems including cancer. CO is a by-product of the...

12 Pollution Effects

The major concern for many years was improving the energy efficiency of industrial combustion processes. The concern has changed in recent years away from energy efficiency toward other issues including pollution emissions 1 . Environmental quality and greenhouse gases are seen as some of the key drivers shaping the future of industrial combustion. Interestingly, the burden of future improvements in industrial combustion processes is seen to fall primarily on academic researchers and equipment...

12324 Burner Design

Some specific examples of the effects of burner design on NOx emissions will be used to illustrate the importance of the burner itself, in addition to its operating conditions. A series of burner designs known as EZ-FireTM were developed by Figure 12.36 Flat-shaped flame burner incorporating lean premixing and furnace gas recirculation. (Courtesy of John Zink Co. LLC, Tulsa, OK.) Figure 12.36 Flat-shaped flame burner incorporating lean premixing and furnace gas recirculation. (Courtesy of John...

173 Textile Manufacturing

The textile manufacturing industry consists of the following segments 26 Broad woven fabric mills and wool mills, including dyeing and finishing Knitting mills and knit goods finishing Other dyeing and finishing textile mills Floor covering mills, including dyeing and finishing. The U.S. EPA ranks textile processing as number 44 on its prioritized list of 59 major source categories where the lower the number the higher the priority 27 . Figure 17.17 Schematic of a textile printing process....

162 Terminology

Hesketh 18 defines a number of terms important in incineration time that volatile matter is exposed to turbulent mixing, elevated temperature, and excess air for final combustion heat-transfer portion of incinerator where water is turned to steam residue from the furnace amount of combustible material in fuel converted into CO2 and H2O total quantity of combined carbon and hydrogen that is converted into CO2 and H2O vapor (usually expressed in lb hr) quantity of waste material loaded into...

1998

Modelling of glass melting industrial process, J. Phys., Vol. 3, Part 7.2, pp. 1357-1366, 1993. 336. BD Paarhuis, AM Lankhorst, M Riepen, JFM Velthuis. A Rapid Simulation Model of the Combustion Space of Glass Melting Furnaces. Fifth International Conference on Technologies and Combustion for a Clean Environment, Lisbon, Portugal, Vol. 2, The Combustion Institute - Portuguese Section, pp. 697-703, 1999. KS Chapman, S Ramadhyani, R Viskanta. Modeling and Analysis of...

Oxygen

Figure 2.8 Air-oxy fuel burner. (From Ref. 23. Courtesy of CRC Press.) 0 10 20 30 40 50 60 70 80 90 100 02 in Oxidizer (vol. ) 0 10 20 30 40 50 60 70 80 90 100 02 in Oxidizer (vol. ) 100 90 80 70 60 50 40 30 20 10 0 Air in Oxidizer (vol, ) Figure 2.9 Oxidizer compositions for blends of air and pure O2. (From Ref. 23. Courtesy of CRC Press.) With this method of using OEC, the oxidizer composition may be specified in an alternative way. Instead of giving the overall O2 concentration in the...

Na2so3 Homemade

Table 1.13 Flue Gas Desulfurization Process 4. Magnesium promoted lime or limestone Sturry scrubbling Na2SO3 Solution Na2SO3 Solution, regenerated by CaO or CaCO3 MgSO3 Solution, regenerated by CaO or CaCO3 Sodium citrate solution H2S Ammonia solution, NH4OH conversion to SO2 Adsorption at 400 K, reaction with H2S to S, reaction with H2 to H2S Absorption by sodium carbonate or slaked lime solutions equipment. If combustors are not properly maintained, then emissions can be adversely affected....

4370 5570 6590 7090

Note uncontrolled emissions are in the range 0.1-0.53 lb MMBtu. Source Ref. 95. (Courtesy of Gas Technology Institute.) Anderson 96 notes the importance of damper control to minimize NOx emissions from fired process heaters. The dampers help ensure the proper draft and O2 levels in the furnace. If the draft conditions are not optimized then tramp air may be pulled into the heater if the draft is too high or not enough air may be pulled in through the burner if the draft is too low. If the O2...

Info

Atmospheres are directly or indirectly produced by combusting hydrocarbon fuels. One example of a furnace that has a protective atmosphere is a bell furnace. The inner part of the furnace has a heated muffle that contains a protective atmosphere, often hydrogen or hydrogen blends. These furnaces are commonly used for annealing steel coils. Another example of a furnace using a protective atmosphere is a roller hearth as shown in Fig. 13.41. The picture shows an entrance vestibule that helps...

6841 Selective Catalytic Reduction

Selective catalytic reduction (SCR) involves injecting a NOx-reducing chemical into an exhaust stream in the presence of a catalyst within a specific temperature window. This process applied to a boiler is shown in Fig. 6.56 88 . The chemical is typically ammonia and the temperature window is approximately 500 to 1100 F (230 -600 C). Figure 6.57 shows how the gas temperature affects the NOx removal efficiency for an SCR process. The NOx and NH3 react on the catalyst surface to form N2 and H2O....

Glass Manufacturing Figure

Flowchart Manufacturing Glass

Figure 14.1 Emissions from minerals production processes. (From Ref. 2.) Table 14.1 Types of Calciners Used in Minerals Processing Industry3 Rotary Flash furnace Kettle furnace aCalciners are not used in the ball clay, bentonite, feldspar, industrial sand, and roofing granules high-temperature melting furnace to produce glass, which may be clear or colored. A schematic of the basic glass manufacturing process is shown in Fig. 14.3 4 . The specific furnace and heat-transfer issues vary slightly...

23 Combustion Properties

Adiabatic Equilibrium Images

This section briefly considers the combustion product composition, flame temperature, available heat, and flue-gas volume for combustion as commonly used in industrial applications. These are important in calculating the heat transfer from the flame, and exhaust gases to the furnace and to the load. There are a number of variables which can have a significant impact on the products of combustion. Some of the important variables include the oxidizer composition, mixture ratio, air and fuel...

S

Using this definition for the mixture ratio, A,-< 1.0 for fuel-rich flames and A,-> 1.0 for fuel-lean flames. Many industrial combustion processes run with approximately 3 more O2 than is theoretically needed for perfect combustion. That is often the amount of excess O2 which is required to minimize the emissions of unburned hydrocarbons and ensure the complete combustion of the fuel. This may be due to mixing limitations between the fuel and the oxidizer, especially in nonpremixed systems....

155 Emission Control Strategies

Table 15.11 lists some common techniques for reducing NOx in process heaters that include a variety of the strategies discussed next 95 . Table 15.12 provides a more detailed list of low-NOx technologies for process heaters based on fuel and draft types. API 535 discusses low NOx burners used in general refinery services 16 . Air staging, fuel staging, internal flue gas recirculation, and external flue gas recirculation are some common techniques used to reduce NOx. API 560 notes that, while...

Printed In The United States Of America

Environmental Science and Pollution Control Series Toxic Metal Chemistry in Marine Environments, Muhammad Sadiq Handbook of Polymer Degradation, edited by S. Halim Hamid, Mohamed B. Amin, and AU G. Maadhah Unit Processes in Drinking Water Treatment, Willy J. Masschelein Groundwater Contamination and Analysis at Hazardous Waste Sites, edited by Suzanne Lesage and Richard E. Jackson Plastics Waste Management Disposal, Recycling, and Reuse, edited by Nabil Mustafa Hazardous Waste Site Soil...

122 Acid Rain

Acid rain is sometimes referred to as acidic deposition. It is formed when air pollutants like NOx and SOx are transported over long distances and are carried to the earth after contacting some type of moisture in the atmosphere e.g., rain and form an acid like nitric acid or sulfuric acid see Fig. 1.10 . Note that although a natural background level of acid rain e.g., from volcanic eruptions has existed for ages, there has been a dramatic increase in acid rain levels in the last two centuries...