Methane yields from

Biogas and Methane Yields from Jerusalem Artichoke... 

Fig. 14. Data illustrating effect of 7-irradiation on the methanation of carbon dioxide over supported Ru catalysts comprising ruthenium on alumina (Ru/Al) or ruthenium in molecular sieve (Ru/M). Effects of 7-irradiation at the indicated temperature on the growth of methane product observed from a continuous flow of C02 in a H2 carrier gas over (i) Ru/M and (ii) Ru/Al. Note the growth in methane yields from C02—H2 reaction at different temperatures as a function of 7 dose and its decay with time subsequent to removal of the catalyst from the 7-source.

Steady-state performance of conventional high-rate mesophilic digestion of the biomass-waste blend at the baseline loading and detention time is presented in Table I. The methane yields from replicate baseline runs ranged... 

Tritiated methane (13.9%) and propane (14.6%) are the major products in the reaction of ions with propane. Smaller amounts of ethane (4.7%), ethylene (4.5%) and traces of butane have also been produced. The above yields are insensitive to the addition of 2 mol% of oxygen as a radical scavenger and to a decrease in pressure from 760 to 20 torr (except for an increase in the methane yield from 14 to 18%). These results have been... 

If this equation Is also valid In the pyrolysis of propane-propylene mixtures, the amount of propylene available for the copyrolysls Is defined as the sum of the propylene fed plus propylene produced from propane evaluated from Equation (23). However, the selectivity was small and could be negligible In the case of low propane to propylene ratio In feed (yCoHo 0.2). Methane yield from propane and propylene was larger chan that of ethylene as shown In Table 1. This result will be caused by hydrogenation and hydrogenolysis of each component. 

Predicted Methane Yields From Bench Data... 

Amon T, Amon B, Kryvoruchko V, Bodiroza V, Potsch E, Zollitsch W (2006) Optimising methane yield from anaerobic digestion of manure effects of dairy systems and of glycerin supplementation. Int Congr Ser 1293 217-220... 

In the BMA process, methane (natural gas) and ammonia are reacted without air being present (44). The reaction is carried out in tubes that are heated externally to supply the endothermic heat of reaction very similar to a reformer. Yield from ammonia and methane is above 90%. The off-gas from the converter contains more than 20 mol % hydrogen cyanide, about 70 mol % hydrogen, 3 mol % ammonia, 1 mol % methane, and about 1 mol % nitrogen from ammonia decomposition. 

One cubic foot (0.03 cu.m) of methane requires 10 cubic feet (0.28 cu.m) of air (2cu.ft (0.06 cu.m) of oxygen and 8cu.ft (0.23 cu.m) of nitrogen) for combustion. The products are carbon dioxide, nitrogen, and water. The combustion product of one cubic foot of methane yields a total of nine cubic feet of carbon dioxide gas. Also, the gas burned contains some ethane, propane, and other hydrocarbons. The yield of inert combustion gas from burning a cubic foot of methane will be 9.33 cubic feet (0.26 cu.m)... 

Although from theoretical considerations biomass yields from methane could be as high as 1.4, in laboratory-scale cultures values of about 1.0 were obtained, and in larger scale systems values were around 0.3-0.6. Methane fermentation also incurs high aeration and cooling costs. 

This paper surveys the field of methanation from fundamentals through commercial application. Thermodynamic data are used to predict the effects of temperature, pressure, number of equilibrium reaction stages, and feed composition on methane yield. Mechanisms and proposed kinetic equations are reviewed. These equations cannot prove any one mechanism however, they give insight on relative catalyst activity and rate-controlling steps. Derivation of kinetic equations from the temperature profile in an adiabatic flow system is illustrated. Various catalysts and their preparation are discussed. Nickel seems best nickel catalysts apparently have active sites with AF 3 kcal which accounts for observed poisoning by sulfur and steam. Carbon laydown is thermodynamically possible in a methanator, but it can be avoided kinetically by proper catalyst selection. Proposed commercial methanation systems are reviewed. 

The SASOL plant was operated with a surplus of C02 during a long term test of 4000 hrs. Of the C02 in the synthesis gas, 33.4% was metha-nated while the remaining 66.6% left the reaction system unconverted. Product gas from final methanation yielded specification grade SNG containing residual hydrogen of 0.7 vol % and residual CO of less than 0.1 vol %. The heating value was 973 Btu/standard cubic foot (scf) after C02 removal to 0.5 vol % (calc.). 

Uddin et al. (2008b) conducted several depressurization simulations for the Mallik 5L-38 well. Their results showed that the Mallik gas hydrate layer with its underlying aquifer could yield significant amounts of gas originating entirely from gas hydrates, the volumes of which increased with the production rate. However, large amounts of water were also produced. Sensitivity studies indicated that the methane release from the hydrate accumulations increased with the decomposition surface area, the initial hydrate stability field (P-T conditions), and the thermal conductivity of the formation. Methane production appears to be less sensitive to the specific heat of the rock and of the gas hydrate. 

Determine the size of the UASB reactor for the treatment of 1275 m /day of wastewater generated from a typical pharmaceutical plant with COD of 16,000 mg/L. The COD removal efficiency at an HRT of 4.7 days is 97%. If the following data and conditions are applicable, estimate (i) OLR and upflow velocity and (ii) methane yield and energy equivalent. 

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