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Document Number | 1231 |
|---|---|
Primary Title | Energy Requirements for Anaerobic Fermentation Systems (Section 4.0) |
Author Name | Chen, Y. R.;Hashimoto, A. G. |
Author Affiliation | U.S. Department of Agriculture, Clay Center, NE |
Editor Name | Hasimoto, A. G.;Chen, Y. R.;Varel, V. H.;Hruska, R. L. |
Published Date | 01/01/1981 |
Detailed Publish Date | Jan 1981 |
Title Source | Anaerobic Fermentation of Beef Cattle Manure. Final Report |
Page Range | 33-45 |
Page Count | 76 |
Document Type | REPORT CHAPTER |
Publisher Name | Solar Energy Research Inst., Golden, CO |
Abstract | This section discussed the energy requirements of anaerobic fermentation systems. The major energy consumption for a thermophilic system is in maintaining the fermenter temperature. Of the total heating energy required, about 89 to 94% was for heating the influent slurry at an ambient temperature of 10 deg C. The need to recover the heat leaving with the effluent is apparent. With 50% effluent heat recovery, the heating energy requirement is reduced from 37.0% to 19.7% of the gross energy production for a 1,000 Mg TS/day plant. The next major energy consumption was due to the mixing of the influent slurry and fermenter liquor. Mixing amounted to 7.3% of the gross methane energy production, assuming continuous mixing. The mixing energy can be reduced greatly if the mixing time is reduced. The least energy was consumed in pumping. Pumping energy did not increase when the pumping time was shortened from 10 to 3 hours. Three hours of pumping has a higher Reynolds number but requires a larger pump and bigger pipes. The total energy consumption excluding thermal energy consumption accounts for 10.8 to 11.3% of the gross thermal energy production. Using the kinetic constants given for different influent concentration and fermentation temperature, it was found that for HRT less than 12 days, the net thermal energy production increased with the influent concentration up to 80 g VS/L and began to drop at influent concentration greater than 80 g VS/L. Also, a longer HRT will produce more net thermal energy at the same influent concentration. The net thermal energy production for 35 deg and 55 deg C were also compared for an influent concentration of 80 g VS/L. This comparsion showed that a thermophilic (55 deg C) system will produce more thermal energy than a mesophilic (35 deg) system unless the fermenter is operated at a very long HRT. |
Report Number | SERI/TR-98372-1 Final Report |
Subcontract No. | DB-9-8372-1;DB-9-08372-01 |
Copyright Status | N - Not copyrighted, |
Document Source | NTIS, Order No. SERI/TR-98372-1 |
Document Owner | B |