Boiler application

The majority of larger industrial burners, including furnace and boiler applications, are of the forced-draft type. These employ a combustion air fan to provide all the air needed for complete combustion. The burners are usually sealed into the combustion chamber so that there is no access to secondary air from the atmosphere as with natural-draft burners. Forced-draft burners may be of the premix type, where air and gas are mixed prior to the burner, or, more commonly, of the nozzle mix type, where the mixing takes place within the burner. 

A recent development in heat recovery has been the heat tube. This is a sealed metal tube which has been evacuated of air and contains a small quantity of liquid which, for boiler applications, could be water. When heat from the flue gases is applied to one end of the heat pipes the water in the tube boils, turning to steam and absorbing the latent heat of evaporation. The steam travels to the opposite end of the tube which is surrounded by water, where it gives up its latent heat, condenses and returns to the heated end of the tube. Batteries of these tubes can be arranged to form units, usually as a water jacket around a section of a flue. 

There are very many industrial processes for which WH/HR boilers may be required, and during some by-product fuel combustion processes, downstream HR boilers can also recover chemicals for reuse upstream. Some WH and special-purpose boiler applications are briefly discussed in the following sections. 

In practice, for any specific boiler application, the various pretreatment and purification techniques employed are incorporated in a sequential train to provide the most cost-effective or operationally effective treatment solution. 

Synthetic resins are extremely widely used, both pre-boiler and postboiler. Pre-boiler, they are employed for basic MU water treatment (e.g., softening) and various higher quality purification processes (e.g. dealkalization and demineralization). Post-boiler applications are for condensate polishing. 

Specific alkalinity ranges should be selected for individual boiler applications and maintained within an 80 ppm range (such as 240-300 ppm). 

Where phosphate-cycle chemistry is employed in WT boilers, a different set of rules apply. However, for non-highly rated boilers, phosphate-cycle programs normally may be employed up to 1,200 psig (82 bar), and phosphate itself is generally satisfactory in industrial applications up to at least 1,885 psig (130 bar), or for any specific boiler application up to the phosphate hideout point. 

For any specific boiler application, the general area of phosphate equilibrium concentration may produce phosphate reserves of below 1.0 ppm P04 and an operating pH level of around 9.0... 

Boilers are heat-transfer devices, wherein water, in the form of either liquid water or gaseous steam, is commonly employed as a medium for the transport of heat to some distant point of use. Although other heat-transfer mediums are sometimes utilized, water is particularly suitable because of its relative abundance, low cost, and high heat capacity. It is generally the medium of choice in most boiler applications, whether for domestic, commercial, institutional, or industrial purposes. 

Conventional riffle box, as shown in Fig. 24, used normally for 2-way splitting in coal-fired furnace and boiler applications. 

Allen, M. G., C. T. Butler, S. A. Johnson, E. Y. Lo, and F. Russo. 1993. An imaging neural network combustion control system for utility boiler applications. Combustion Flame 94 205-14. 

The world of codes and standards is an absolute labyrinth, so the emphasis here will be only on the main issues from ASME and PED, which cover about 80% of all worldwide requirements. The exceptions are China and India, who follow their own guidelines, although they are mostly focused on boiler applications. Also, we will concentrate on the industrial process applications and only refer to these applicable codes. 

If emission of the fluid into the atmosphere is acceptable, the spring housing may be vented to the atmosphere in an open bonnet design, as shown in Figure 5.11. This is usually advantageous when the SRV is used on high-temperature fluids or for boiler applications as otherwise,... 

United States ASME I ASME III ASME VIII ANSI/ASME PTC 25.3 Boiler applications Nuclear applications Unfired pressure vessel applications Safety and relief valves - performance test codes... 

Applications that can bum whole tires include a few cement kilns, large dedicated tires-for-fuel boilers, and some experimental applications in utility boilers. Applications that can use TDF include most cement kilns, many thermal decomposition units, boilers at pulp and paper plants, utility plants, and other industrial facilities. 

These include plants that manufacture chemicals, glass, grain, steering and gear manufacturing, and tractors. These other industrial processes are grouped together, and are discussed in Chapter 7, Supplemental TDF Use in Other Boiler Applications. 

Varied boiler firing configurations are found in hog fuel boiler applications, including dutch oven, fuel cell, spreader stoker with traveling or vibrating grates, and cyclone stoker types. As stated previously, the spreader stoker is the most widely used of these configurations. Spreader/stoker boilers in the pulp and paper industry often have an air swept spout added to the front of the boiler to feed bark down on top of the coal.14 Wood is puffed at one-... 

Model-based boiler optimization schemes have proved successful in many power plant and industrial boiler applications. Successful NOx reduction through this kind of optimization can avoid or postpone large capital expenditures for low NOx burners, over-fire air modifications, and selective catalytic reduction/selective noncatalytic reduction (SCR/SNCR). 

Closed-loop multivariable boiler control has to be planned and performed carefully because plant operators are not traditionally willing to reduce air-fuel ratios due to concerns about CO and other symptoms associated with Oz-deficient combustion. Model predictive control (MPC) is by far the most widely used technique for conducting multivariable boiler optimization and control. Forms of MPC that are inherently multivariable and that include real-time constrained optimization in the design are best suited for boiler application. 

Table IV gives the properties of the SRC-II fuel oil compared to a low-sulfur residual oil utilized in a recent combustion test. The SRC-II fuel oil is a distillate product with a nominal boiling range of 350-900°F, a viscosity of 40 Saybolt seconds at 100°F and a pour point below -20°F. Thus, it is readily pumpable at all temperatures normally encountered in transportation of the fuel oil. The fuel oil has a very low content of ash and sediment as well as a low Conradson carbon residue. These characteristics are favorable from the standpoint of particulate emissions during combustion. Tests of compatibility with typical petroleum fuel oils and on stability of the coal distillates over time have not revealed any unusual characteristics that would preclude utilization of these coal-derived fuels in conventional boiler applications.

Of the SRC evaluated, the CSD SRC has the highest potential for success in a utility boiler application from the standpoint of achieving low carbon content fly ash under low N0X (staged) combustion operating conditions. 

Lead is immune to distilled water free from C02 and oxygen. Air free from C02 in distilled water corrodes lead. In presence of C02 a film of basic lead carbonate in formed, which prevents further attack. The successful use of lead pipe coils for steam boiler applications depends on the use of pure water condensate, which is free from oxygen and carbon dioxide. In the event of the presence of oxygen, oxygen scavengers such as hydrazine or sodium sulfite together with cobalt nitrate may be used. 

Benson, S., Steadman, E. N., Zygarlicke, C. J. Erickson, T. A. (1996), Ash Formation, Deposition, Corrosion, and Erosion in Conventional Boilers. Applications of Advanced Technology to Ash-Related Problems in Boilers, Plenum Press, New York, p. 1. 

At VTT, the following issues are addressed in the present study pyrolysis of solid biomass [3, 4], hot vapour filtration, pyrolysis oil quality [5] and fuel oil specifications [6], storage and handling properties of pyrolysis oil, boiler applications [7], and techno-economic assessment of pyrolysis systems [8]. A considerable amount of work... 

It would be quite impractical for a power utility plant to use the raw coal input to Plant C because of the likelihood emission standards would be out-of-compliance more frequently than regulations permit. Likewise, the high ash in the raw coal feed to Plant A makes it very undesirable for utility boiler applications. These high-sulfur high-ash coals must be cleaned, otherwise there would be essentially no market for them. 

An advantage of the cascade dryer over the rotary drum dryer is the reduced space requirement, which may be critical when installing a dryer in combination with an existing boiler. Applications have been mainly as predryers in combination with wood-fuel boilers in saw and pulp mills. 

Pyrolysis is the treatment of plastic waste in the presence of heat under controlled temperatures without catalysts. The pyrolysis process is an advanced conversion technology, in which the hydrocarbon content of the waste is converted into a clean, high calorific value gas from a wide variety of plastic waste. The produced gas can be utilized in gas engines, electricity generation, or in boiler applications. 

Jones G D, Johnson K L (1979) Technology Assessment Report for Industrial Boiler Applications NOx Flue Gas Treatment. U.S. Environmental Protection Agency, EPA-600/7-79-178 g, Austin, Texas... 

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