Fuel addition rate

In practice, the efficiency of a fired heater is controlled by monitoring the oxygen concentration in the combustion products in addition to the stack gas temperature. Dampers are used to manipulate the air supply. By tying the measuring instruments into a feedback loop with the mechanical equipment, optimization of operations can take place in real time to account for variations in the fuel flow rate or heating value. 

Compounds of magnesium can be added to fuel containing vanadium to help combat its corrosive effects. Typical addition rates range from 2 1 Mg V at a 1200°F (648.9°C) operating temperature and 3 1 Mg/V at a 1,500°F (815.5°C) operating temperature. However, the total ash content must still be monitored. 

Hindered phenol compounds usually possess alkyl groups on ortho and para sites. The alkyl groups are typically t-butyl or methyl in functionality. The lower cost of hindered phenol antioxidants makes them attractive for use in fuel applications. In gasoline, hindered phenols are typically used at treat rates of 5 to 50 ppm. The limitations placed on jet fuel additives often control the rate at which phenolic antioxidants can be used. 

A fuel oil stabilizer additive listed in QPL-24682 may be blended into naval distillate fuel at rates up to 35 lb/1,000 barrels to protect against degradation and improve storage stability as measured by ASTM D-5304. Method ASTM D-2274 may also be used if the test duration is extended from 16 to 40 hours. 

The ASTM D-3948 Water Separation Index, Modified (WSIM) Test is used to identify the emulsifying tendencies of additives in jet fuel. A high concentration of film-forming corrosion inhibitors has been shown to severely degrade the water separation tendencies of jet fuel. Treat rates as low as 20 ppm of some inhibitors can degrade the WSIM to a failing rating. 

Ethyleneglycol monomethylether (EGME) and diethyleneglycol mono-methylether (DEGME) are both approved as additives to help prevent ice crystal formation in jet fuel. At a maximum treat rate of 1500 ppm, these compounds have minimal effect on degrading the jet fuel MSEP rating. 

The high content of water and emulsifier in this fuel creates some differences in handling and application compared to conventional diesel fuel. The surfactant quality of the emulsification additive in the fuel can remove existing deposits from the internal surfaces of fuel handling and storage systems. Problems with fuel discoloration and fuel filter plugging may follow. Compared with conventional diesel, fuel economy ratings per tank of fuel will drop because the overall carbon content per unit volume of fuel is lower. This is due to carbon displacement by water. 

We believe it has been shown that this method for infrared analysis of hydrocarbons collected on charcoal tubes and vapor monitors is a valid and acceptable one. Further work is being done to validate the method for other hydrocarbons such as petroleum naphtha, Stoddard solvent, and other JP aviation fuels. Additionally, work is being done to determine the 3M monitor sampling rate for JP-4. 

The desire to improve the octane rating of fuels after the refining process without the use of lead has intensified a search for other "antiknock compounds. For example, compounds of Mn (5) and Ce (9) have been explored for this purpose. Methylcyclopentadienyl manganese tricarbonyl, in particular, is already being marketed for octane improvement. At a recommended level of 0.125 g Mn/gal, 200-500 g of Mn can be expected to pass the exhaust system within 50,000 miles. The main criteria in accepting such fuel additives are their compatibility with catalytic systems, and, of course, health-safety considerations. 

Fig. 15.5. Typical pressure drop and concentration-time curves of a diesel particulate trap in a closed gas-loop experiment with constant heating rate for the characterization of catalyst or filter performance for the combustion of diesel soot. Sintered SiC ceramic filter, without catalyst coating or fuel additive (from Ref. [46]).

Shrestha et al (2005) conducted a study in which SME, mustard seed oil methyl and ethyl esters and used peanut oil methyl esters were blended (B0, B5 and B10) with No. 2 petrodiesel and treated with six commercial petrodiesel CFI additives. It was found that at 100, 200, and 300% of the specified loading rate, CP and PP were reduced by an average of 2.2 °C and 14.1 °C, respectively. Mustard seed oil ethyl esters exhibited the highest average reduction in CP and PP and SME exhibited the lowest, as shown by Table 1.9 for CP. Furthermore, a significant decrease in CP was noticed when additive concentration was increased from 100% of the specified loading rate to 200% however, the difference between 200% and 300% was not significant. The authors conclude that the effect of fuel additive is not only different for different feedstocks but also some fuel additives worked better for a specific blend of biodiesel with No. 2 petrodiesel. 

Before an experiment with a new fuel additive formulation, the engine was conditioned to the new fuel for 24 hours. After this period, a filter was placed in an oven that was attached to a side stream of the exhaust system. Exhaust gas was pumped through the filter with a vacuum pump, at a controlled rate of typically 8 -10 l jp/min. The pressure drop over the filter was measured and recorded, together with other data such as filter exhaust temperature, fuel consumption, etc. 

If you know the fuel feed rate and the stoichiometric equation(s) for complete combustion of the fuel, you can calculate the theoretical O2 and air feed rates. If in addition you know the actual feed rate of air, you can calculate the percent excess air from Equation 4.8-1. It is also easy to calculate the air feed rate from the theoretical air and a given value of the percentage excess if 50% excess air is supplied, for example, then... 

A joint research program (Hydrocarbon Research, Inc.—Cities Service Research and Development Co.) has been underway for more than three years at the HRI laboratories to develop a demetallization procedure which would reduce the nickel and vanadium contents of fuel oils and thus produce an oil for further processing by H-Oil at low catalyst addition rates. These research eflForts have resulted in the development of solid adsorbent materials which are low in cost and which eflFectively remove the bulk of the organo-metallic compounds present in such oils. These solids are used in an H-Oil reactor with the conventional ebullated-... 

Ethyl Antiknock Compounds [Albemarle], TM for a series of fuel additives containing various percentages of tetraethyl lead, ethylene dibromide, ethylene dichloride, dye, kerosene, and antioxidant. All are used to improve the octane rating of motor fuels. 

Coproduct -butanol is produced at the rate of about 2.2 kg per kilogram of propylene, and is converted to methyl -butyl ether for sale as an automotive fuel additive. 

The removal of soot from diesel exhaust gas is preferably done catalytically. Fuel additives and supported molten salts are promising catalyst for this application. NO in the exhaust gas can be used to increase the soot oxidation rate. 

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