Concentrated Alkali Metal Hypochlorite Process Low Chlorate
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Solution Overview
Problem
The synthesis of high-concentration bleach results in excessive chlorate formation, which is undesirable when added to drinking water due to regulatory requirements for low chlorate content.
Innovation Solution
A process involving the reaction of chlorine and alkali metal hydroxide in the presence of alkali metal chloride crystals within a vertically designed vessel, where the reactants are injected and recycled to fluidize the crystals, controlling the reaction rate and residence time to maintain chlorate concentrations between 0.01% and 0.2% by weight, effectively minimizing chlorate formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-concentration bleach is synthesized by reacting chlorine with sodium hydroxide, then transport costs are reduced and stability is improved, but chlorate formation increases excessively
Solution Approach 1:
The patent applies preliminary action by pre-cooling the sodium hydroxide solution to temperatures below 30°C before introducing it to the reaction vessel. This preliminary cooling prevents the temperature from rising during the exothermic reaction, thereby suppressing the parasitic chlorate formation reaction while still allowing high-concentration bleach synthesis. The cooling is performed in advance to establish favorable conditions before the main reaction occurs.
Solution Approach 2:
The patent changes the temperature parameter by maintaining the reaction temperature below 30°C through continuous cooling. This parameter change fundamentally alters the reaction kinetics, favoring the desired hypochlorite formation while suppressing the chlorate formation reaction. The temperature control is achieved by cooling the sodium hydroxide solution before reaction and maintaining cooling throughout the process.
2Object-generated harmful factors
If standard bleach concentration is used, then chlorate formation is reduced, but transport efficiency and stability are compromised
Solution Approach 1:
The patent changes the temperature parameter to below 30°C and maintains this condition throughout the reaction and storage process. This parameter change enables the system to achieve high bleach concentration (superior to standard bleach) while simultaneously suppressing chlorate formation to levels below regulatory limits. The low temperature parameter fundamentally resolves the contradiction between concentration and chlorate content.
Solution Approach 2:
The patent applies continuity of useful action by implementing continuous cooling throughout the entire process - from pre-cooling the sodium hydroxide solution, through maintaining temperature during the exothermic reaction, to keeping the final product at low temperature during storage. This continuous temperature control ensures that high concentration is maintained without allowing temperature rise that would trigger chlorate formation.
3Productivity
If temperature is increased during synthesis, then reaction rate increases, but chlorate formation is favored
Solution Approach 1:
The patent changes the temperature parameter to a specific range below 30°C and maintains it throughout the reaction. This parameter change optimizes the reaction conditions to achieve acceptable reaction rates while fundamentally suppressing the chlorate formation reaction, which is highly temperature-sensitive. The controlled low temperature prevents the parasitic reaction while still allowing the main hypochlorite formation to proceed efficiently.
Solution Approach 2:
The patent applies preliminary action by pre-cooling the sodium hydroxide solution to below 30°C before the reaction begins. This preliminary temperature control ensures that even though the reaction is exothermic, the temperature does not rise enough to favor chlorate formation. The pre-established low temperature condition maintains productivity while preventing harmful byproduct formation.
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 process produces a concentrated alkali metal hypochlorite solution with low chlorate content, suitable for use in drinking water without exceeding regulatory limits, and allows for easy dilution to remove chloride crystals, maintaining stability and solubility of the product.
Implementation Method 1
the recycling and the injection of the reactants from step a) are adjusted so that the alkali metal chloride crystals are fluidized essentially in the bottom part of the vessel
Implementation Method 2
reacting one molecule of chlorine with sodium hydroxide
Implementation Method 3
The temperature of the solution inside the vessel and in the recycling circuit is preferably kept below 35° C. to prevent the formation of chlorate
Data Source
AI summary
The present invention relates to a process for preparing concentrated alkali metal hypochlorite solutions. One subject of the invention is more particularly a process for preparing concentrated bleach which may have a chlorine content of greater than 100 chlorometric degrees, and that has a low content of chlorates.