Excess percent

As an example, consider heavy fuel oil (CH15, specific gravity, 0.95) atomized to a surface mean particle diameter of d, burned with 20 percent excess air to produce coke-residue particles having the original drop diameter and suspended in combustion products at 1204°C (2200°F). The flame emissivity due to the particles along a path of L m will be, with d in micrometers. 

Example 8 Ejfective Gas Emissivity Methane is hiimed to completion with 20 percent excess air (air half-saturated with water vapor at 298 K (60 F), 0.0088 mols H20/mol dry air) in a furnace chamber of floor dimensions. 3 X 10 m and heights m. The whole surface is a gray-energy sink of emissivity 0.8... 

This equation has two unknowns Xq and Xe), and an empirical relation between them is needed. Many have been tried, and one of the best is to assume that the excess of To over Te expressed as a ratio to Tp (zero for a perfectly stirred chamber) is a constant A [ (Tg — Tg)/ Tp]. Although A should vaiy with burner type, the effects of firing rate and percent excess air are small. In the absence of performance data on the land of furnace under study, assume A = 300/Tp, °R or 170/Tp, K. The left side of Eq. (5-178) then becomes D 1 —Xc + A), and with coefficients of Xc and Xc collected, the equation becomes... 

Excess air is usually 30 to 40 percent for stationary and dumping grates, while traveling grates are operated with from 22 to 30 percent excess air. Preheated air can be supplied for all types of grates but the temperature is usually limited to 395 to 422 K (250 to 300°F) to prevent excessive slagging of the fuel bed. 

The hot combustion gas preheats the fresh air and the prereformer, and can be used further to generate steam. The system is cooled with 200 to 300 percent excess air, A 25-kW S()F(i generator system is shown in Fig, 27-69,... 

The ACF is the actual cubic feet of gas measured at t, F and P, psig. SCF represents standard conditions at 70 F and 14.6 psia. The formulas provided require input information on the pressure and temperature of the fuel gas, the fuel gas analysis by volume (or mole percent if the pressures are sufficiently low), and the percent excess air. The calculation provides the air to fuel ratio required for complete combustion. 

Ts = Average stack gas temperature, °K. This temperature depends on the heating value of the flare gas and the percent excess air. It may be assumed that Tj = 1538 C = 1811 K, which is a reasonable approximation and is further justified by the fact that Equation 4 is relatively insensitive to changes in T. ... 

The relative natural abundance of a. stable i.sotope i.s important becau.se, in tracer studies, die amount of stable i.sotope is typically expres.sed in terms of atoms percent excess over the natural abundance of die i.sotope. 

Figure 6 Percent excess flash by elastomer type for 11-s mold closure.

Factor of safety or percent excess area should be at least 10-15%. 

Assuming a linear relationship between [a] and concentration, which is true for most cases, the optical purity is equal to the percent excess of one enantiomer over the other ... 

Applications Electrodeposition of cationic paint resin on automobiles (connected to the cathode) provides a uniform, defect-free coating with high corrosion resistance, but carries with it about 50 percent excess paint that must be washed off. UF is used to maintain the paint concentration in the paint bath while generating a permeate that is used for washing. The spent wash is fed back into the paint path (Zeman et al., Microjiltration and UltrajUtration, Marcel Dekker, New York, 1996). 

Going to extremes, the reactivity of internal acetylenic triple bonds compared with terminal olefinic double bonds was also checked. Diallyl ethers of commercial 2-butyne-l,4-diol and 3-hexyne-2,5-diol are available in high yield by phase transfer etherification. They are reacted under essentially the same conditions as those described in section 3.1, with the double bond now being in 100 percent excess at the beginning (Eq. 4). 

Water Dew Point For flue gas, the water dew point is that temperature at which the actual water vapor pressure equals the water saturation vapor pressure. Cooling the flue gas below this temperature will result in the formation of liquid water [or ice, below 273 K (0°C)]. For example, burning natural gas with 3 percent excess oxygen (15 percent excess air), the flue gas water dew point would be (Fig. 24-57) 330K(56.7°C). 

The tertiary amine thus obtained was dissolved in absolute ethanol and was refluxed for two days with five molar percent excess of the appropriate bromoalkane (97% Humphrey Chemical, North Haven, Conn.). Solvent was removed and the residue in aqueous Na2C03 solution was extracted with hexane to remove any unreacted bromoalkane. Next, the N-alkyl N-benzyl N-methylglycine was extracted into chloroform from the aqueous layer. Solvent was stripped off and the crude material was recrystallized thrice from carbon tetrachloride and twice from THF/CHCl3 (60 40 v/v) mixture. The yields of the purified betaines were about 75% of the theoretical. 

The tertiary amine thus obtained was dissolved in absolute ethanol and refluxed for five days with five molar percent excess of the appropriate bromoalkane. Thereafter, the procedure was similar to that for the N-alkylglycines. Crude product was recrystallized thrice from water and then from THF/CHCl3 (50 50 v/v) mixture. 

A measure of the amount of a stable isotopic label that exceeds its natural abundance in unlabeled tracee. This is most directly accomplished using an ion ratio mass spectrometer to measure the ratio of ion currents for isotopomers such as C02 at mass 44 and 2 at mass 45. From the difference between the ion current ratio for a sample (Zsampie) and the ion current ratio for a reference gas (Zreference), the atom percent excess (APE) can be estimated. See Tracer/Tracee Ratio Compart-mental Analysis Isotope Exchange Kinetics... 

ASPARTATE CARBAMOYLTRANSFERASE ATMOSPHERE ATOM PERCENT EXCESS TRACER/TRACEE RATIO COMPARTMENTAL ANALYSIS ISOTOPE EXCHANGE KINETICS ATOMIC MASS UNIT ATOMIC ORBITAL ATOMIZATION ATP... 

ATOM PERCENT EXCESS OXYGEN ISOTOPE EXCHANGE COMPARTMENTAL ANALYSIS ISOTOPE EXCHANGE KINETICS GRAPHICAL METHODS... 

Figure 2-8 shows plots of Xn versus the stoichiometric ratio for several values of p in accordance with Eq. 2-78. The stoichiometric imbalance is expressed as both the ratio r and the mole percent excess of the B—B reactant over the A—A reactant. The various plots show how r and p must be controlled so as to obtain a particular degree of polymerization. However, one does not usually have complete freedom of choice of the r and p values in a polymerization. Complete control of the stoichiometric ratio is not always possible, since reasons of economy and difficulties in the purification of reactants may prevent one from obtaining r values very close to 1.000. Similarly, many polymerizations are carried out to less than 100% completion (i.e., to p < 1.000) for reasons of time and economy. The time required to achieve each of the last few percent of reaction is close to that required for the first 97-98% of reaction. Thus a detailed consideration of Fig. 2-2 shows that the time required to go fromp = 0.97 (X = 33.3) to p = 0.98 (X — 50) is approximately the same as that to reach p = 0.97 from the start of reaction. 

Quite often, the specifications of a product are based not on the requirements of that product but on what is achievable in practice. When total sulfur removal is required, it is not uncommon that 20 to 30 percent excess carbide is employed. All of this excess carbide then ends up as slag and creates a large disposal problem. If the iron were desulfurized only to the extent actually needed, much of this waste could be reduced or eliminated (Stephens 1988). 

For example, if a higher sulfur content is acceptable, the foundry will not have to go to the far end of what the calcium carbide desulfurization treatment process will produce. Instead of having to add a 20 or 30 percent excess calcium carbide to the molten metal for complete desulfurization, a lower dose could be used, resulting in far less unspent calcium carbide in the waste therefore, the wastes may not be classified as reactive hazardous waste. 

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