Alkali Injection Reduces Chip Pump Wear in Prehydrolysis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional prehydrolysis kraft cooking systems experience accelerated chip pump wear due to acidic conditions, leading to increased friction and wear rates, which are 5-10 times higher than in alkaline systems, causing operational inefficiencies.
Innovation Solution
Increasing the pH level in the prehydrolysis Kraft cooking feed system to a range of 7-10, preferably 8-9.5, by adding white liquor or other alkaline chemicals directly to the chip pump, specifically between the impeller and the pump casing, to reduce wear and maintain efficient auto-hydrolysis processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If acidic conditions (pH ~5) are maintained in the prehydrolysis feed system, then auto-hydrolysis reactions proceed efficiently, but chip pump wear rate increases 5-10 times
Solution Approach 1:
The patent applies local quality by introducing alkali specifically at the chip pump location (between impeller and liner) to create a localized alkaline environment (pH 7-10) only where needed for pump protection, while maintaining acidic conditions (pH ~5) in the rest of the prehydrolysis system for efficient auto-hydrolysis. This spatial differentiation resolves the contradiction between pump wear and hydrolysis efficiency.
Solution Approach 2:
The patent changes the pH parameter locally in the chip pump region from acidic (~5) to alkaline (7-10) by adding alkali, while maintaining acidic conditions in the prehydrolysis reactor. This parameter change reduces pump wear rate by 5-10 times without significantly affecting auto-hydrolysis efficiency in the main system.
2Reliability
If alkali is added to increase feed system pH to reduce pump wear, then chip pump wear rate decreases, but auto-hydrolysis reactions are slowed down
Solution Approach 1:
The patent confines the alkaline environment (pH 7-10) to the chip pump region only, while maintaining acidic conditions (pH ~5) in the prehydrolysis reactor where auto-hydrolysis occurs. This localized approach ensures pump protection without significantly interfering with the auto-hydrolysis reaction rate in the main system.
Solution Approach 2:
The patent introduces alkali as an intermediary substance specifically at the chip pump location to mediate between the conflicting requirements of pump durability and hydrolysis efficiency. The alkali creates a protective alkaline zone around the pump while allowing the main system to maintain acidic conditions optimal for auto-hydrolysis.
3Reliability
If alkali is added directly to the chip pump, then pump wear is reduced with minimal disturbance to prehydrolysis, but the system complexity increases
Solution Approach 1:
The patent implements self-service by having the chip pump system treat its own wear problem through localized alkali addition. The alkali is introduced directly into the pump housing where it immediately neutralizes acidic conditions causing wear, allowing the pump to protect itself without requiring system-wide modifications or complex external protection mechanisms.
Solution Approach 2:
The patent extracts the pH control function from the overall prehydrolysis system and applies it independently to the chip pump subsystem. By separating the pH management of the pump from the main hydrolysis system, the patent reduces overall system complexity while achieving pump protection through localized treatment.
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
Significantly reduces chip pump wear rates with minimal disturbance to the prehydrolysis stage, requiring only a small amount of alkaline chemicals, thus improving system efficiency and extending pump lifespan.
Implementation Method 1
the pH level in a prehydrolysis Kraft cooking feed system is increased to a range 7-10, preferably 8-9.5, by adding white liquor or other alkali to prevent chip pump wearing
Implementation Method 2
The transport device may be one or more centrifugal pumps arranged in series
Data Source
AI summary
A method for feeding a slurry of chips and liquid to a prehydrolysis reactor in the production of dissolving pulp. The slurry is pumped by using at least one pump to the reactor, and alkali is fed into the at least one pump 5 for adjusting the pH of the slurry to a range of 7-10.