| 摘要 |
<p>CHEMICAL RECOVERY UTILIZING EVAPORATION STEAM AND EXCHANGERS IN STEAM STRIPPING SYSTEM A method of treating waste liquors such as those derived from the sulfite or Kraft pulp making process is disclosed which provides recovered by-products of high purity while moreover decreasing the total amount of process steam required. The method comprises steam stripping the evaporator condensate feed to remove volatile chemical by-products therefrom, and thereafter directing the stripping steam for reuse in concentrating additional volumes of feed in the evaporator. In this manner, the only steam lost during the stripping operation is that used for increasing the sensible heat of the evaporator condensate feed within the steam stripping column. The condensed steam and volatile by-products resulting from evaporator heating operation are then preferably directed to a fractionation column or columns in order to separate and recover the valuable by-products for reuse of sale. In situations where the condensate feed contains volatile, noncondensible gases which are valuable for reuse, the evaporator condensate feed may be preheated and contacted with evaportator vent gases. The latter are partially condensed to allow the noncondesible gases to be recovered and reused, and the condensed liquor is cooled and passed through an activated carbon column prior to steam stripping in order to facilitate the recovery of chemical by-products and enhance the purity thereof.</p> |
