초록 ▼

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

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 or 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 evaporator vent gases. The latter are partially condensed to allow the noncondensible 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.

대표청구항 ▼

A process for treating waste liquors such as condensates and spent liquors derived from chemical processing operations, comprising the steps of: directing said liquors to an evaporation zone; heating said liquors in said evaporation zone to effect concentration of the liquors therein with consequent

A process for treating waste liquors such as condensates and spent liquors derived from chemical processing operations, comprising the steps of: directing said liquors to an evaporation zone; heating said liquors in said evaporation zone to effect concentration of the liquors therein with consequent evolution of vapors, said heating including the step of directing a heating medium which includes steam to the evaporation zone for indirectly heating and concentrating at least a portion of said liquors therein; condensing said vapors; directing at least a portion of the condensed vapors to a stripping zone; stripping at least a portion of the chemical constituents within said condensed vapors by subjecting the latter to the action of stripping steam in the stripping zone; and directing at least a fraction of said stripping steam, after the latter has acted to strip chemical constituents from the condensed vapors in said stripping zone, back to said evaporation zone as at least a part of said heating medium for heating and concentrating additional volumes of liquor in the evaporation zone.