Brine Purification via Evaporative Crystallization
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Solution Overview
Problem
Existing methods for purifying brine solutions for the chlor-alkali process face challenges due to high consumption of chlorine gas or hypochlorite, difficulty in oxidizing oxygen-containing organic compounds, and environmental concerns from chlorinolysis, which limits the effectiveness and efficiency of using brine in industrial processes.
Innovation Solution
A process involving one or two-stage evaporative crystallization to purify brine by crystallizing sodium chloride, separating and redissolving it in a solution with reduced organic compound concentration, using forced circulation evaporative crystallizers and separation devices to achieve a high-purity brine with low total organic carbon (TOC) levels, thereby reducing the need for excessive chlorine usage and improving environmental safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If chlorinolysis is used to reduce organic compound concentration in brine, then organic compound removal is achieved, but substantial amounts of chlorine gas or hypochlorite are consumed
Solution Approach 1:
The patent applies preliminary action by performing evaporative crystallization to remove water and concentrate the brine before chlorinolysis. This pre-concentration step reduces the volume of brine requiring subsequent chemical treatment, thereby reducing the amount of chlorine gas or hypochlorite needed for organic compound removal while still achieving the required TOC level for chlor-alkali process feedstock
Solution Approach 2:
The patent segments the brine purification process into distinct stages: evaporative crystallization to separate water from dissolved solids, followed by chlorinolysis of the concentrated brine. This segmentation allows each process to operate optimally - evaporation handles bulk water removal while chlorinolysis focuses on organic compound destruction in a smaller volume, reducing overall chlorine consumption
2Quantity of substance
If ozonolysis is used to oxidize organic compounds, then organic compounds are converted to volatile fragments and carbon dioxide, but the process requires elevated temperature and dissolved ozone
Solution Approach 1:
The patent applies parameter changes by utilizing the natural solubility characteristics of ozone at different temperatures. By conducting ozonolysis at lower temperatures where ozone has higher solubility, the process achieves effective oxidation of organic compounds without requiring elevated temperature conditions, thereby reducing energy consumption while maintaining treatment effectiveness
3Quantity of substance
If evaporation is used to concentrate brine, then water is removed to form crystals and mother liquor, but energy consumption increases
Solution Approach 1:
The patent applies the extraction principle by removing water from the brine through evaporative crystallization, separating it from the dissolved solids. This extraction of water concentrates the brine and organic compounds into a smaller volume, facilitating more efficient subsequent treatment steps while the removed water can be reused or disposed of separately, reducing the energy burden on downstream processing
4Loss of substance
If industrial brine is used in the chlor-alkali process, then raw material acquisition costs are reduced, but impurities must be reduced to very low concentration
Solution Approach 1:
The patent applies preliminary action by implementing a pre-treatment train (evaporative crystallization followed by chlorinolysis) to reduce impurity concentrations in industrial brine before it enters the chlor-alkali electrolysis process. This preliminary purification ensures that when cheaper industrial brine is used, it meets the strict feedstock specifications required for efficient electrolytic conversion, thereby maintaining cost savings while achieving the required product purity
Solution Approach 2:
The patent introduces intermediary treatment processes between the industrial brine source and the chlor-alkali electrolysis cell. These intermediary steps (evaporation and chlorinolysis) act as mediators that transform the impure industrial brine into suitable feedstock, enabling the use of lower-cost raw materials while protecting the sensitive electrolysis process from harmful impurities
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 process effectively reduces TOC levels in brine solutions to meet chlor-alkali process requirements, conserves chlorine gas and hypochlorite, and minimizes environmental impact by optimizing the purification of brine for reuse in industrial applications.
Implementation Method 1
a first forced circulation evaporative crystallizer for crystallizing sodium chloride in the aqueous brine solution to form sodium chloride crystals and a first mother liquor
Implementation Method 2
a first separation device for separating the sodium chloride crystals from the first mother liquor
Implementation Method 3
a first dilution vessel for redissolving the separated sodium chloride crystals in an aqueous solution having an organic compound concentration substantially less than the organic compound concentration in the aqueous brine solution
Implementation Method 4
conduct chlorinolysis to oxidize organic compounds to more volatile oxidation fragments and/or carbon dioxide that can be stripped from the aqueous brine solution
Implementation Method 5
conduct ozonolysis to oxidize organic compounds to more volatile oxidation fragments and/or carbon dioxide that can be stripped from the aqueous brine solution
Data Source
AI summary
Processes and apparatus for purifying brine are provided including (1) providing an aqueous brine solution comprising one or more inorganic salts and one or more organic compounds and (2) conducting at least one unit operation for removing organic compounds from the brine solution to obtain a purified brine solution.