Fuels consumption

Figure 6.30 shows the grand composite curve plotted from the problem table cascade in Fig. 6.186. The starting point for the flue gas is an actual temperature of 1800 C, which corresponds to a shifl ed temperature of (1800 — 25) = mS C on the grand composite curve. The flue gas profile is not restricted above the pinch and can be cooled to pinch temperature corresponding to a shifted temperature of 145 C before venting to the atmosphere. The actual stack temperature is thus 145 + 25= 170°C. This is just above the acid dew point of 160 C. Now calculate the fuel consumption ...

The fuel consumption is now calculated by taking the flue gas from theoretical flame temperature to ambient temperature ... 

The gradual reduction and ultimate elimination of lead has seen considerable effort by the refiner to maintain the octane numbers at satisfactory levels. In Europe, the conventional unleaded motor fuel, Eurosuper, should have a minimum RON of 95 and a minimum MON of 85. These values were set in 1983 as the result of a technical-economic study called RUFIT (Rational Utilization of Fuels in Private Transport). A compromise was then possible between refining energy expenses and vehicle fuel consumption (Anon., 1983). 

In 1993, French consumption of these products was around 6 Mt and 2.5 Mt respectively for use in burners and in diesel engines. The latter figure appears in the statistics under the heading, marine bunker fuel . Its consumption been relatively stable for several years, whereas heavy industrial fuel use has diminished considerably owing to the development of nuclear energy. However, it seems that heavy fuel consumption has reached a bottom limit in areas where it is difficult to replace, e.g., cement plants. 

Trends in refining costs for a capacity of8 10>> t/an. Excluding fuel consumption. 

Joint TMCf SyPE Fuel Consumption Test Procedure, Type 2, SAE J1321, SAE Recommended Practice Approved October 1981, Society of Automotive Engineers, Warrendale, Pa., 1981. 

X 10 Btu/short ton), the solar energy trapped in 17.9 x 10 t of biomass, or about 8 x 10 t of biomass carbon, would be equivalent to the world s fossil fuel consumption in 1990 of 286 x 10 J. It is estimated that 77 x 10 t of carbon, or 171 x 10 t of biomass equivalent, most of it wild and not controlled, is fixed on the earth each year. Biomass should therefore be considered as a raw material for conversion to large suppHes of renewable substitute fossil fuels. Under controlled conditions dedicated biomass crops could be grown specifically for energy appHcations. 

A projection of biomass energy consumption in the United States for the years 2000, 2010, 2020, and 2030 is shown in Table 6 by end use sector (12). This analysis is based on a National Premiums Scenario which assumes that specific market incentives are appHed to aU. new renewable energy technology deployment. The scenario depends on the enactment of federal legislation equivalent to a fossil fuel consumption tax. Any incentives over and above those in place (ca 1992) for use of renewable energy will have a significant impact on biomass energy consumption. 

Benefits resulting from better control of glass melting ate lower fuel consumption, better glass quality, more efficient production time, and better pollution control. Fewer operators are needed and working conditions are better. 

Helping to propel capacities upward has been the advent of greatly improved preheaters, which partially calcine the stone and significantly improve thermal efficiency. Modem preheaters improve capacity by 15—20% and decrease fuel consumption a similar percentage. Other kiln appurtenances and accessories that enhance efficiency and lime quahty are the contact coolers, and such kiln internals as metal refractory trefoil systems that act as heat exchangers, dams, and lifters. 

To reduce drying time, maximum airflows are used during the first portion of the kilning cycle until the exit air is no longer saturated with moisture. Airflow then is reduced or recirculated to conserve energy. Average fuel consumption for a United States kiln is ca 5.9 x 10 kJ/t (1.4 x 10 kcal/t) ) malt, with a range of 2.9-10 X 10 kJ/t of malt. 

Boron, in the form of boric acid, is used in the PWR primary system water to compensate for fuel consumption and to control reactor power (3). The concentration is varied over the fuel cycle. Small amounts of the isotope lithium-7 are added in the form of lithium hydroxide to increase pH and to reduce corrosion rates of primary system materials (4). Primary-side corrosion problems are much less than those encountered on the secondary side of the steam generators. 

The primary water specifications for a PWR are given in Table 1 (4). Rigid controls are appHed to the primary water makeup to minimise contaminant ingress into the system. In addition, a bypass stream of reactor coolant is processed continuously through a purification system to maintain primary coolant chemistry specifications. This system provides for removal of impurities plus fission and activated products from the primary coolant by a combination of filtration (qv) and ion exchange (qv). The bypass stream also is used both to reduce the primary coolant boron as fuel consumption progresses, and to control the Li concentrations. 

The Model 412 PWR uses several control mechanisms. The first is the control cluster, consisting of a set of 25 hafnium metal rods coimected by a spider and inserted in the vacant spaces of 53 of the fuel assembhes (see Fig. 6). The clusters can be moved up and down, or released to shut down the reactor quickly. The rods are also used to (/) provide positive reactivity for the startup of the reactor from cold conditions, (2) make adjustments in power that fit the load demand on the system, (J) help shape the core power distribution to assure favorable fuel consumption and avoid hot spots on fuel cladding, and (4) compensate for the production and consumption of the strongly neutron-absorbing fission product xenon-135. Other PWRs use an alloy of cadmium, indium, and silver, all strong neutron absorbers, as control material. 

The third control is by use of a fixed burnable poison. This consists of rods containing a mixture of aluminum oxide and boron carbide, included in the initial fuel loading using the vacant spaces in some of the fuel assembhes that do not have control clusters. The burnable poison is consumed during operation, causing a reactivity increase that helps counteract the drop owing to fuel consumption. It also reduces the need for excessive initial soluble boron. Other reactors use gadolinium as burnable poison, sometimes mixed with the fuel. 

Estimates for 1993 are preliminary for prior years are final. Estimates are for steam-electric plants >10 MW, based or 1 fuel consumption data. ... 

Because of demands for improved fuel consumption through reduced rolling resistance, a new series of carbon blacks referred to as LH, ie, N300 with this innovation would be N300 LH. Basically this series of blacks has a wider size range in both the primary particles and primary aggregates in addition to a more chemically active surface area. 

Dehydrogenation of isobutane to isobutylene is highly endothermic and the reactions are conducted at high temperatures (535—650°C) so the fuel consumption is sizeable. Eor the catalytic processes, the product separation section requires a compressor to facHitate the separation of hydrogen, methane, and other light hydrocarbons from-the paraffinic raw material and the olefinic product. An exceHent overview of butylenes is avaHable (81). 

Fouling organisms attach themselves to the underwater portions of ships and have a severe impact on operating costs. They can increase fuel consumption and decrease ship speed by more than 20%. Warships are particularly concerned about the loss of speed and maneuverabiHty caused by fouling. Because fouling is controUed best by use of antifouHng paints, it is important that these paints be compatible with the system used for corrosion control and become a part of the total corrosion control strategy. 

Instead of gas turbine exhaust, air preheat has been used in some plants to reduce fuel consumption. Flue gas leaving the furnace stack passes through an air preheater, and the preheated air is suppHed to the burners. By using mostly hearth burners, the duct work and the investment cost can be minimised with air preheat and gas turbine exhaust. It is also possible with 100% waH-fired furnaces, and has been proven in commercial operation (34). 

Fig. 2. Effect of mixture strength on exhaust gas composition (dry basis) and brake specific fuel consumption (BSFC) for an unsupercharged automotive-type engine usiag iadolene fuel, H/C = 1.86, where the ignition is tuned to achieve maximum best torque (MBT), the brake mean effective...

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