Aspirating Agitator for Chlorinated Propane Synthesis
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Solution Overview
Problem
There is a need to improve the synthetic techniques for producing 1,1,1,3-tetrachloropropane, an important halogenated propane, as existing methods may not be efficient or effective in achieving high yields and product purity.
Innovation Solution
The process involves reacting carbon tetrachloride with ethylene in a tank reactor with an aspirating agitator, which transfers ethylene from the headspace back into the reaction mixture, and using an iron-based catalyst delivered through a continuously stirred slurry loop. Additionally, the chlorinated propane product is removed from a still zone within the reactor, and the crude product stream is purified using a distillation technique with a forced circulation reboiler to prevent fouling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If ethylene is fed as vapor through a dip tube or sponge-type gas diffuser, then polyvinyl chloride formation is reduced, but reaction efficiency and contact between reactants is insufficient
Solution Approach 1:
The patent introduces an aspirating agitator as an intermediary device that uses a gas stream to actively transfer ethylene from the headspace back into the reaction mixture. This mediator enables efficient mass transfer without direct gas-liquid contact issues that cause polyvinyl chloride formation, thereby resolving the contradiction between reducing harmful byproducts and maintaining high reaction efficiency.
Solution Approach 2:
The aspirating agitator creates periodic circulation patterns where ethylene is continuously drawn from the headspace and reintroduced into the liquid phase. This periodic action ensures consistent reactant contact and maintains high reaction efficiency while preventing the continuous gas flow issues that lead to polyvinyl chloride formation.
2Productivity
If the reactor is agitated to provide adequate contact between liquid reactants and metallic iron surface, then reaction efficiency improves, but polyvinyl chloride formation increases
Solution Approach 1:
The patent segments the reactor into distinct zones: a liquid reaction mixture zone with controlled agitation for catalyst contact, and a vapor headspace zone. The aspirating agitator selectively transfers ethylene between these zones without requiring intense overall agitation, thus maintaining reaction efficiency while minimizing conditions that promote polyvinyl chloride formation.
Solution Approach 2:
The patent applies local quality by providing agitation specifically where needed - at the liquid-catalyst interface to ensure adequate contact - while using the aspirating mechanism to handle gas-phase ethylene transfer separately. This localized approach to agitation reduces overall mixing intensity and prevents excessive polyvinyl chloride formation while maintaining reaction efficiency.
3Device complexity
If carbon tetrachloride and ethylene are reacted in a single reactor with continuous agitation, then synthesis is simplified, but temperature control and reactant contact become difficult
Solution Approach 1:
The aspirating agitator serves multiple functions simultaneously: it provides mild mechanical agitation for reactant contact, creates vapor-liquid circulation for improved mass transfer, and facilitates heat distribution throughout the reaction mixture. This multi-functionality maintains synthesis simplicity while addressing temperature control challenges.
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 enhances reaction efficiencies by ensuring adequate contact between reactants and catalysts, improves product yield and purity, and prevents fouling during distillation, thereby optimizing the production of chlorinated propanes.
Implementation Method 1
ethylene gas diffuses from the liquid reaction mixture into the headspace while agitating the reaction mixture
Implementation Method 2
transferring ethylene within the headspace back into the reaction mixture through a conduit within the mixing device that agitates the reaction mixture
Implementation Method 3
reacting carbon tetrachloride with vinyl chloride in the presence of an iron catalyst and tributylphosphate
Implementation Method 4
The reactor effluent is distilled to recover catalyst and ultimately isolate the desired 1,1,1,3,3-pentachloropropane product
Implementation Method 5
purified using a distillation technique with a forced circulation reboiler to prevent fouling
Data Source
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AI summary
A process of the type for producing chlorinated propanes by reacting carbon tetrachloride with ethylene within a tank reactor that includes a liquid reaction mixture and a headspace above the reaction mixture wherein ethylene gas diffuses from the liquid reaction mixture into the headspace while agitating the reaction mixture, the improvement comprising transferring ethylene within the headspace back into the reaction mixture through a conduit within the mixing device that agitates the reaction mixture.