Boilers, utilities

Simple thermodynamic calculations show that thermal NO is not a significant contributor to total NO. Thermal NO occurs at very low rates below 1600°F. Consequently thermal NO is not a concern for FCC unit regenerators, most of which operate below 1400°F. However, thermal NO is often a significant fraction for partial-bum regenerators because the CO boilers utilized in partial-bum operation typically operate in excess of 1600°F. 

One boiler utilizing TDF on a continual test basis, Otter Tail Power, bums lignite as a primary fuel.21 Because lignite has a relatively low Btu content (6200 Btu/lb), TDF offers improved flame stability to their operation.12... 

Transportation Solid waste disposal Stationary fuel combustion Industrial boilers Utility boilers Industrial processes Miscellaneous sources... 

By far the most common use of petroleum is as gasoline for automobiles and trucks. About 90 percent of the petroleum used in the United States fuels vehicles powered by internal combustion engines. Diesel fuel is used to power trucks, buses, trains, and some automobiles. Heating oil warms buildings and powers industrial boilers. Utilities use residual fuel oil to generate electricity. Jet fuel, produced from kerosene, powers airplanes. Some airplanes use aviation... 

Currently, the largest single use for scrap tires is as a fuel in power plants, cement plants, pulp and paper mill boilers, utility boilers, and other industrial boilers. At least 100 million scrap tires were used in 1994 as an alternative fuel either in whole or chipped form... 

BBC Brown Boveri BV has made an estimation of investment cost and operating eost for an ozone generation plant on bases of a 700 MW boiler, eontaining 500 ppm NOj in the off gas. The investment cost adds to about 2.0 10E7 ECU (excluding reactor for flue gas and ozone) and operating costs to 2.6 10E6 ECU ear (boiler utilization 6130 h/year). 

J.Ando has given an estimation of SCR cost for new power plants (eonventional diy bottom boiler), based on a 700 MW eoal fired boiler and a boiler utilization of 6100 h ear [6]. 

Another advantage of integration into an industrial cluster is that the existing infrastructure (boilers, utility systems, air separation plant, etc.) is already in place. Compared to a stand-alone biorefmery unit, this can have positive impact on process economics since, for example, parts of the infrastructure for electricity, steam, waste water, safety, etc. can be shared (Kimm, 2008). 

Figure 6.25a shows the same grand composite curve with two levels of saturated steam used as a hot utility. The steam system in Fig. 6.25a shows the low-pressure steam being desuperheated by injection of boiler feedwater after pressure reduction to maintain saturated conditions. Figure 6.256 shows again the same grand composite curve but with hot oil used as a hot utility. 

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... 

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. 

The utility system also creates waste through products of combustion from boilers and furnaces and wastewater from water treatment, boiler blowdown, etc. Utility waste minimization is in general terms a question of ... 

This technology has since been introduced to the fossil power generating industry. To-date, several major utilities including the Termessee Valley Authority, Baltimore Gas and Electric and American Electric Power, as well as many others, have employed this technology to assess the condition of power-generating boiler tubes. 

Validating the final experimental protocol was accomplished by running a model study in which Nd was released into the atmosphere from a 100-MW coal utility boiler. Samples were collected at 13 locations, all of which were 20 km from the source. Experimental results were compared with predictions determined by the rate at which the tracer was released and the known dispersion of the emissions. 

D. S. Ensor, R. G. Hooper, R. C. Carr, and R. W. Scheck, "Evaluation of a Eabric Eilter on a Spreader Stoker Utility Boiler," Preprint 76-27.6, 69th APCA.JinnualMeeting, Portland, Oregon, June 27—July 1, 1976. 

There has been increased interest in firing wood waste as a supplement to coal in either pulverized coal (PC) or cyclone boilers at 1—5% of heat input. This appHcation has been demonstrated by such electric utilities as Santee-Cooper, Tennessee Valley Authority, Georgia Power, Dehnarva, and Northern States Power. Cofiring wood waste with coal in higher percentages, eg, 10—15% of heat input, in PC and cyclone boilers is being carefully considered by the Electric Power Research Institute (EPRI) and Tennessee Valley Authority (TVA). This practice may have the potential to maximize the thermal efficiency of waste fuel combustion. If this practice becomes widespread, it will offer another avenue for use of fuels from waste. 

K. A. Bueters and W. W. Habelt, NO Emissionsfrom Tangentially Fired Utility Boilers, AIChE Symposium Series, Vol. 71, American Institute of Chemical Engineers, New York, 1975, Parts I—II. 

The overall yield of the process is at least 87 mol %, and 2.3 mol of methanol per mole of final product are needed, an excess of 15% over the 2.0 theoretical amount. The methanol can be recycled from the manufacture of poly(ethylene terephthalate). Reported utilities consumptions per kilogram of product are 1.2 kg of 1400-kPa steam, 420 kj of boiler fuel, and 0.5 kWh of electricity (72). 

Can a gas turbine be utilized for power generation upstream of the boiler ... 

Table 2. Boiler-Water Limits for Utility Boiler ...

In the United States, the largest concentration of atmospheric vanadium occurs over Eastern seaboard cities where residual fuels of high vanadium content from Venezuela are burned ia utility boilers. Coal ash ia the atmosphere also coataias vanadium (36). Ambient air samples from New York and Boston contain as much as 600—1300 ng V/m, whereas air samples from Los Angeles and Honolulu contained 1—12 ng V/m. Adverse pubHc health effects attributable to vanadium ia the ambieat air have aot beea deteroiiaed. lacreased emphasis by iadustry oa controlling all plant emissions may have resulted ia more internal reclamation and recycle of vanadium catalysts. An apparent drop ia consumption of vanadium chemicals ia the United States since 1974 may be attributed, in part, to such reclamation activities. 

Industrial by-products are becoming more widely used as raw materials for cement, eg, slags contain carbonate-free lime, as well as substantial levels of silica and alumina. Fly ash from utility boilers can often be a suitable feed component, because it is already finely dispersed and provides silica and alumina. Even vegetable wastes, such as rice hull ash, provide a source of silica. Probably 50% of all industrial by-products are potential raw materials for Pordand cement manufacture. 

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