Polysulfide Electrolysis Scale Inhibition
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Solution Overview
Problem
The challenge in the polysulfide production process is the rise in electrolytic bath voltage over time, leading to increased maintenance frequency and reduced polysulfide production efficiency due to scale deposition, which necessitates frequent acid washing and component replacement, disrupting continuous operation.
Innovation Solution
Incorporating a scale inhibitor, such as a maleic acid-type polymer, and a scale cleaning agent, like a chelating agent, into the sulfide ion-containing white liquor to prevent scale formation and maintain electrolysis without halting the process, thereby reducing maintenance needs and stabilizing the bath voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If electrolysis is performed continuously to produce polysulfide, then productivity is improved, but scale deposition occurs on the anode and membrane causing voltage to rise over time
Solution Approach 1:
The patent applies preliminary action by adding a scale inhibitor to the white liquor before electrolysis begins. This preventive measure stops scale from forming on the anode and membrane surfaces during continuous operation, thereby maintaining stable voltage and avoiding the need for shutdowns for cleaning, thus resolving the contradiction between continuous productivity and voltage stability.
2Reliability
If acid washing is performed frequently to remove scale deposition, then reliability is improved, but productivity is reduced due to process interruption
Solution Approach 1:
The patent converts the harmful effect of scale deposition into a beneficial situation by using a scale inhibitor that prevents scale formation in the first place. This eliminates the need for frequent acid washing and process interruptions, thereby maintaining both high reliability and continuous productivity simultaneously.
3Productivity
If conversion rate is increased in polysulfide cooking process, then productivity is improved, but thiosulfate ion is secondarily produced in large amounts reducing selectivity
Solution Approach 1:
The patent applies parameter changes by controlling the electrolysis conditions (current density, temperature, pH) to favor the formation of polysulfide ions while minimizing secondary reactions that produce thiosulfate. By optimizing these parameters, the system achieves high conversion rates while maintaining high selectivity for polysulfide production.
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
The method allows for long-term, stable operation of the electrolytic bath by preventing scale deposition, reducing acid wash frequency, and maintaining polysulfide production efficiency with minimal impact on current density and voltage rise, thus lowering operational costs.
Implementation Method 1
Incorporating a scale inhibitor, such as a maleic acid-type polymer
Implementation Method 2
a scale cleaning agent, like a chelating agent, into the sulfide ion-containing white liquor to prevent scale formation
Implementation Method 3
production of polysulfide ion through electrolytic oxidation by introducing a sulfide ion-containing solution into the anode compartment
Implementation Method 4
electrolytic oxidation by introducing a sulfide ion-containing solution into the anode compartment
Data Source
AI summary
An electrolysis method of preventing the voltage of an electrolytic bath from rising over time without halting electrolysis and an electrolysis device for executing the method are provided such that: in operation of a two-compartment electrolytic bath, which has a membrane partitioning an anode compartment from a cathode compartment and in which a sulfide ion-containing white liquor for use in a pulp production process is fed into the anode compartment while direct current is supplied to the electrolytic bath to produce polysulfide in the anode compartment through electrolysis, and a sulfide ion-containing white liquor for use in a pulp production process that contains at least one of a scale cleaning agent and a scale inhibitor is fed to the anode compartment.