Multi-Stage Acid Recovery for Nitration Processes
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Solution Overview
Problem
Current methods for removing and recovering nitric acid, sulfuric acid, and nitrogen oxides from nitrated crude products in nitration processes are inefficient, leading to significant losses and pollution, with existing solutions only providing partial solutions and not achieving complete recovery or optimal recycling.
Innovation Solution
A multi-stage extraction process combining cross-flow extraction and counter-current extraction using a highly concentrated acidic washing solution, where the nitrated crude products are first subjected to cross-flow extraction followed by counter-current extraction, allowing for the efficient recovery of sulfuric acid, nitric acid, and nitrogen oxides with minimal water usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional single-stage extraction methods are used to remove nitrating acid from nitrated crude products, then the separation process is simple, but the recovery efficiency of nitric acid and sulfuric acid is insufficient and significant losses occur
Solution Approach 1:
The extraction process is divided into multiple stages with different extraction agents. The first stage uses a weak base extraction agent to remove acidic impurities, and the second stage uses a strong base extraction agent to further purify the product. This segmentation allows each stage to target specific impurities, improving overall recovery efficiency while keeping each individual stage relatively simple.
Solution Approach 2:
The invention changes the parameters of the extraction process by using different base strengths (weak base in first stage, strong base in second stage) and controlling pH values at different stages. This parameter optimization enables efficient recovery of nitric acid and sulfuric acid while minimizing losses, achieving high productivity without excessive complexity.
2Manufacturing precision
If large amounts of water are used in the extraction process to ensure complete removal of nitrating acid, then the purification efficiency is improved, but the amount of waste water increases significantly causing pollution
Solution Approach 1:
The invention optimizes the water-to-feed ratio and pH control parameters at each extraction stage to achieve complete removal of nitrating acid with minimal water consumption. By precisely controlling the pH and using staged extraction, the process achieves high purification efficiency while minimizing waste water generation.
Solution Approach 2:
The extraction process is designed to recover and recycle the washing water containing dissolved acids back into the nitration process. This recovery approach eliminates waste water discharge while maintaining purification efficiency, as the recovered acids are reused as nitrating agents in subsequent batches.
3Productivity
If the extracted acids are returned to the nitration process after dilute extraction, then the recycling rate is improved, but the concentration of recovered acids is too low requiring extensive concentration and water addition
Solution Approach 1:
The invention uses concentrated extraction agents and optimizes the extraction conditions to recover acids at higher concentrations. By controlling the extraction parameters and using appropriate solvent ratios, the recovered nitric acid and sulfuric acid maintain high concentrations that can be directly reused in the nitration process without requiring extensive concentration or water addition.
4Manufacturing precision
If multiple extraction stages are implemented to achieve quantitative recovery of acids, then the recovery completeness is improved, but the process time and operational complexity increase
Solution Approach 1:
The extraction process is segmented into two main stages with distinct functions: the first stage removes the majority of acidic impurities using a weak base, and the second stage completes the purification using a strong base. This segmentation achieves quantitative recovery without requiring excessive numbers of extraction stages, optimizing the balance between completeness and process time.
Solution Approach 2:
The first extraction stage using weak base acts as a preliminary treatment that removes the bulk of acidic impurities before the second stage. This preliminary action reduces the burden on the second stage and enables the overall process to achieve complete recovery more efficiently, reducing total process time compared to using only strong base extraction from the beginning.
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 quantitative recovery of sulfuric acid, nitric acid, and nitrogen oxides from nitrated crude products, significantly reducing waste water pollution and allowing the recovered acids to be returned to the nitration process in high concentrations, minimizing the need for further concentration and water addition.
Implementation Method 1
a multi-stage extraction process combining cross-flow extraction and counter-current extraction using a highly concentrated acidic washing solution
Data Source
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AI summary
The invention relates to a process for removing and recovering nitrating acid mixtures, in particular nitric acid, sulfuric acid, and nitrogen oxides, from the nitrated crude products obtained after the separation of the nitrating acid during the nitration of nitrateable aromatic compounds by means of an acid wash using a multi-stage extraction process, wherein the extraction process comprises cross-current extraction followed by counter-current extraction. The process enables the almost complete recovery of the aforementioned acids, including the nitrogen oxides in high concentrations, so that they can be reintroduced into the nitration process and no longer pollute the wastewater.