Regeneration furnaces

Costs do not include sludge dewatering and disposal costs. b Existing carbon regeneration furnace on site. 

The capacity of regeneration furnaces is selected so that they operate 80-90% of the time. In multiple-hearth furnaces the loading is 70-80 lb/(sqft)(day). In countercurrent direct fired rotary kilns, a 6% volumetric loading is used with 45 min at activation temperature. 

Worldwide, about 180 million tonnes of sulfuric acid are produced per year. 70% comes from burning elemental sulfur. The remainder comes from S02 in smelter, roaster and spent acid regeneration furnace offgases. 

Fig. 4.5. Dynawave scrubber for removing particulate and soluble impurities from cooled (600 K), partially cleaned furnace offgas (Puricelli et al., 1998 Enviro-chem, 2005). Note the (i) upward sprays in and (ii) the weir atop the downcomer. The sprays clean the gas. The weir continuously overflows water, which wets and cools the downcomer walls. These scrubbers are used for both metallurgical and spent acid regeneration furnace gases. Large scrubber details are downcomer diameter 1 m (Hastelloy G30)...

When the efficiency of the activated carbon is diminished by coating the snrface of the activated carbon with adsorbed material, reactivation is reqnired.This is accomplished by oxidizing the adsorbed material in regeneration furnaces at temperatnres aronnd 1470°F (800°C), or chemical treatment with phosphoric acid, potassinm hydroxide, or zinc chloride. 

VOCs released in the process are partially destroyed in the regeneration furnace and finally oxidized at high efficiency by an afterburner. 

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