Purge Stream Segmentation for Terephthalic Acid Purification
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Solution Overview
Problem
Conventional purge processes in terephthalic acid production expel both detrimental and non-detrimental oxidation byproducts, leading to increased waste treatment costs and reduced product yield, as they cannot differentiate between beneficial and detrimental byproducts.
Innovation Solution
A process that separates a purge feed stream into a non-benzoic acid byproduct rich stream and a catalyst and benzoic acid rich stream, allowing for the recycling of non-detrimental byproducts and the removal of detrimental ones, thereby optimizing product yield and reducing waste treatment costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional purge process is used to remove oxidation byproducts, then the TPA product is rendered suitable for use in production processes, but both detrimental and non-detrimental byproducts are expelled together, leading to increased waste treatment costs and reduced product yield
Solution Approach 1:
The purge feed stream is segmented into multiple distinct streams based on byproduct type: a non-detrimental byproduct rich stream (containing bi-functional compounds like 4-CBA) and a detrimental byproduct rich stream (containing mono-functional compounds like benzoic acid). This segmentation allows selective routing where non-detrimental byproducts can be recycled back to the oxidizer while detrimental byproducts are removed for waste treatment, thereby reducing waste treatment costs and minimizing loss of valuable substances
Solution Approach 2:
The process extracts and separates specific non-detrimental byproducts (particularly bi-functional compounds) from the mixed purge feed stream using fractional crystallization and filtration techniques. By taking out these valuable byproducts separately, the system enables their recovery and reuse in the oxidation process, while the remaining detrimental byproducts are disposed of separately, thus resolving the contradiction between removing harmful factors and preserving useful substances
2Object-affected harmful factors
If a conventional purge process is used to remove oxidation byproducts, then the TPA product is rendered suitable for use in production processes, but waste treatment costs increase due to treating all byproducts as waste
Solution Approach 1:
The process converts what would normally be waste (non-detrimental byproducts in the purge stream) into a beneficial resource by separating and recycling them back to the oxidizer. The bi-functional compounds that were previously treated as waste are now reused as feedstock, transforming the waste treatment burden into a value-recovery opportunity while still effectively removing the truly harmful detrimental byproducts
3Object-affected harmful factors
If a conventional purge process is used to remove oxidation byproducts, then the TPA product is rendered suitable for use in production processes, but product yield decreases due to expulsion of useful byproducts
Solution Approach 1:
The process selectively discards only the detrimental byproducts (mono-functional compounds like benzoic acid) while recovering and recycling the non-detrimental byproducts (bi-functional compounds like 4-CBA). This selective discarding and recovering approach maintains product quality by removing harmful impurities while preserving useful substances that can contribute to product yield when fed back into the oxidation process
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 enables the selective routing of non-detrimental oxidation byproducts back into the production process, increasing product yield and decreasing waste treatment costs by distinguishing between beneficial and detrimental byproducts.
Implementation Method 1
separating at least a portion of the purge feed stream into a non-BA byproduct rich stream and a catalyst and BA rich stream
Data Source
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AI summary
Disclosed is a process and apparatus for treating a purge stream in a carboxylic acid production process. The process employs a purge process that allows for the separation of oxidation byproducts into benzoic acid and non-benzoic acid oxidation byproducts, thus providing flexibility in the treatment and use of such oxidation byproducts.