Pulp Starch Preservation Using Chloramine in Papermaking Water
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Solution Overview
Problem
Recycled pulp in papermaking often experiences starch degradation due to microbial activity, leading to reduced mechanical properties, odor issues, and scaling problems in paper and packaging manufacturing, which existing biocides fail to address effectively.
Innovation Solution
A method involving the use of chloramine and an oxidant, such as sodium hypochlorite, to treat process water in papermaking systems, maintaining residual chloramine levels between 0.3 ppm to 15 ppm, and continuously treating for at least a month to control amylase-producing bacteria and reduce starch-degrading enzyme activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard biocides are used to control bacteria, then bacterial growth is suppressed, but starch degradation continues due to amylase enzymes
Solution Approach 1:
The patent changes the chemical parameter of the biocide from conventional agents to chloramine (formed by reacting chlorine with ammonia or ammonium compounds). This parameter change allows simultaneous achievement of bacterial control and starch preservation, as chloramine specifically inhibits amylase enzyme activity while maintaining biocidal effectiveness.
Solution Approach 2:
The patent introduces chloramine as an intermediary substance that mediates between the conflicting requirements of bacterial control and starch preservation. Chloramine acts as a selective agent that targets both bacteria and amylase enzymes without degrading starch, thus resolving the contradiction between these two functions.
2Strength
If recycled pulp with high starch content is used, then mechanical properties improve, but starch degradation occurs during manufacturing
Solution Approach 1:
The patent applies preliminary action by treating the recycled pulp with chloramine before the starch degradation can occur during manufacturing. This pre-treatment establishes protective conditions that prevent amylase activity throughout the subsequent processing steps, preserving starch content and mechanical properties.
Solution Approach 2:
The patent ensures continuity of useful action by maintaining chloramine treatment throughout the entire manufacturing process. This continuous presence of chloramine continuously inhibits amylase activity, preventing starch degradation at any stage from recycling through final product formation.
3Productivity
If microbial activity is allowed to proceed, then fermentation occurs, but VFAs accumulate causing pH decrease and calcium precipitation
Solution Approach 1:
The patent applies preliminary anti-action by using chloramine to prevent the harmful effects of microbial activity before they occur. Chloramine inhibits amylase enzymes that break down starch into fermentable sugars, thereby preventing VFA production and pH decrease upstream in the causal chain, rather than treating symptoms downstream.
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 preserves starch content, enhances paper strength, reduces odor-causing materials, and minimizes microbiological-related breaks and scaling issues, resulting in improved mechanical properties and increased efficiency in paper production.
Implementation Method 1
treating said process water containing said pulp with chloramine comprising monochloramine such that said process water has a residual chloramine amount of from 0.3 ppm to 15 ppm
Implementation Method 2
further treating said process water containing said pulp with at least one oxidant
Data Source
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AI summary
Methods to preserve starch present in pulp are provided and also methods to control calcium precipitation and/or scaling in digesters or BOD systems. The methods can be performed as part of a papermaking process. Process water containing pulp can be treated with a chloramine. Process water containing pulp with native starch can receive a double treatment with at least one biocide, such as chloramine, and at least one oxidant, such as sodium hypochlorite. The treatment can be performed in any suitable manner. The treatment can be performed at one or more stages or locations in a papermaking system. A target residual chloramine value or range can be achieved by the treatment. Packaging sheets/boards and other paper products manufactured using the methods provided exhibit superior strength and other desirable characteristics.