| Résumé : |
Tanneries generate considerable quantities of sludge, shavings, trimmings, hair, buffing dusts and other general wastes as a natural consequence of leather production. On a daily basis, this mass of wet solid wastes can exceed the mass of hides received and processed. Tanneries are also major energy users, which according to Best Practice requires up to 30 kW of energy to "produce" a single finished hide. The waste disposed, usually to landfill, contains more than half of the energy value of coal, at 20 MJ/ kg (10 B.t.u./lb) and if recovered and converted into useful energy could satisfy all of a tannery's own heat energy requirement for leather processing. The pressures upon global landfill disposal are growing, via restrictions to disposal routes and increases to costs/ ton, in parallel with international demands to increase the use of renewable energy. The BLC Combined Drying and Gasification process accommodates both demands; by elimination of tannery solid wastes, whilst providing a combustible gas as a tax-exempt renewable energy source which the tannery can directly reuse. The ash can also be sold as chrome3+ containing ash for reconstitution. This has been achieved via pilot scale, prototype and now demonstration scale plant. These trials have illustrated that up to 70% of the intrinsic energy value of the wastes currently disposed, can be recovered as "synthesis gas" energy. This can be put to useful work, in both drying the wastes pre gasification and as an energy source for the tannery's own boilers (furnaces) CHP or electricity export from the site. At least 60% of the syngas energy recovered is surplus to the gasification process requirements and can be reused by the tannery directly. On full scale, this thermal energy available to the tannery could be equal to that thermal energy actually consumed during leather manufacture. |
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Accueil
Gasification : Achieving zero waste in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. XCVIII, N° 1 (01/2003)
