Process for displacement washing of porous media
US4297164A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 10, 1980 |
| Grant date | Oct 27, 1981 |
| Priority date | — |
| Expiry date | Mar 10, 2000 |
Classification
- Technology area (CPC D)Textiles; Paper
- CPC primaryD21C9/02
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
An improved displacement washing process for recovering processing chemicals from a porous medium, particularly wood pulp, is described. The effective mobility of a displacing solution, typically a more dilute solution of the chemical sought to be recovered, is reduced such that it is less than the mobility of the solution to be recovered. In a pulp mill washing system, consumption of wash water may be reduced 0.6 tons of water per ton of pulp produced without reducing chemical recovery. Conversely, chemical effluent from the washer could be reduced by 50% without increasing wash water requirement. Mobility is proportional to the permeability of the porous medium with respect to the solution of interest and inversely proportional to the viscosity of that solution. Mobility of the wash solution relative to the solution to be displaced is preferrably reduced by the addition of a soluble, high molecular weight polymer, greater than 10.sup.6, until the ratio of the mobility of the wash solution to that of the chemical rich solution is in the range of 0.05-2.0, preferably within the range of 0.2-1. As examples, copolymers of acrylamide and acrylic acid, carboxypolymethylene, polyacrylic…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.