Impregnation Vessel Hydraulic Isolation in Continuous Digestion
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Solution Overview
Problem
Existing impregnation methods in continuous digestion systems are not adaptable to different cooking technologies and rely on black liquor from the digester, limiting flexibility and efficiency.
Innovation Solution
The method involves using fluid withdrawn from a top separator as impregnation fluid, heated by hot black liquor in a heat exchanger, and supplemented with white liquor, allowing for independent operation from the digester process and reducing black liquor dependency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If black liquor is used as impregnation fluid, then the impregnation can be carried out using existing digester fluid, but the system loses adaptability to different cooking technologies and becomes dependent on digester operations
Solution Approach 1:
The patent segments the impregnation system from the digester system by using a top separator to divide fluid streams. The top separator allows selective withdrawal of fluid for impregnation purposes, creating an independent impregnation fluid source that is not tied to digester operations or black liquor production.
Solution Approach 2:
The top separator acts as an intermediary device between the digester and the impregnation vessel. It mediates the fluid flow by selectively withdrawing fluid from the feed line, allowing the impregnation system to operate independently while still utilizing the digester's fluid handling infrastructure.
2Loss of energy
If black liquor is used for impregnation, then heat energy can be conserved through the hot fluid, but the system cannot maintain hydraulic isolation from digester processes
Solution Approach 1:
The top separator creates separate fluid pathways: one for black liquor to the recovery process and another for impregnation fluid to the impregnation vessel. This segmentation maintains hydraulic isolation between digester processes and impregnation operations while preserving heat energy through the hot impregnation fluid.
3Ease of operation
If steam pre-treatment is used for chips, then the chips can be prepared for impregnation, but the process complexity and energy consumption increase
Solution Approach 1:
The patent extracts the pre-treatment function from the steam generation system and integrates it into the impregnation fluid heating process. By heating the impregnation fluid using the top separator's hot fluid, the system eliminates the need for separate steam pre-treatment while maintaining effective chip preparation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables flexible impregnation across various cooking technologies like LO-Solids, MCC, and EMCC, maintaining heat energy efficiency and reducing steam pre-treatment requirements, while maintaining hydraulic isolation from digester fluid flows.
Implementation Method 1
heated by hot black liquor in a heat exchanger
Data Source
AI summary
A method for impregnating chips in a continuous digestion system with an impregnation vessel and a digester. The digestion system has a heat exchanger arranged between a first return line and a black liquor line. The heat exchanger allows a transfer of heat between the two lines. A principal part of the fluid contents of the impregnation vessel is constituted by chips moisture, steam condensate, added white liquor, and the fluid withdrawn from the top separator at the first return line, whereby the impregnation fluid in the impregnation vessel does not contain any substantial amount of black liquor from the digester. An impregnation vessel is established that is hydraulically isolated, in which the flow of fluid and the establishment of its alkali content take place without any influence from the fluid flow in the digester process.