| 摘要 |
PROBLEM TO BE SOLVED: To dehydrate sludge to a specified water content in a short time without using a flocculant at all by adjusting the temp. of steam coming from a boiler to a specified temp. with a total-enthalpy steam generator and blowing the steam directly into sludge in a vacuum tank to quickly increase the sludge temp. to thereby convert the sludge into an association colloid. SOLUTION: After the temp. of steam coming from a steam boiler 8 is adjusted to 70-140 deg.C with a total-enthalpy steam generator 9 comprising a let down valve and a pressure control valve, the resultant total-enthalpy steam is directly blown from a nozzle 19 for total-enthalpy steam into sludge 3 in a vacuum tank 1. The sludge temp. is elevated to a certain evaporation temp., converting the sludge into an association colloid and accelerating evaporation. Thus, sludge having a water content of about 98% can be quickly heated with a total-enthalpy steam having an overall coefficient of heat transfer of about 3,000 kcal/m2.hr. deg.C or higher to be converted into an association colloid and dehydrated to a water content of about 99.6% in a short time. moreover, the running and initial costs can be greatly reduced.
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