Sulfuric Acid Concentration with Oxidative Impurity Removal
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Solution Overview
Problem
Existing processes for concentrating sulfuric acid with nitroaromatic and nitric acid impurities lead to the formation of solid carbonaceous precipitates and spontaneous decomposition of organic impurities, causing equipment fouling, pressure shocks, and damage.
Innovation Solution
A process involving multiple evaporation stages with controlled temperatures and pressures, combined with the addition of an oxidizing agent or its precursor in the third evaporation stage, to selectively decompose organic impurities into volatile components, preventing precipitate formation and decomposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the third evaporation stage is operated at high temperature (180-250°C) to concentrate sulfuric acid efficiently, then productivity is improved, but solid carbonaceous precipitates form causing equipment fouling and reliability deterioration
Solution Approach 1:
The harmful organic impurities (nitroaromatic compounds) are extracted and removed from the sulfuric acid stream through controlled oxidation in the third evaporation stage, converting them into volatile components that can be separated, thereby preventing precipitate formation and equipment fouling while maintaining high concentration efficiency
Solution Approach 2:
The oxidation state parameter is changed by introducing an oxidizing agent in the third evaporation stage, transforming organic impurities from a stable, precipitate-forming state into volatile oxidation products, thus resolving the contradiction between high-temperature concentration and equipment fouling
2Manufacturing precision
If the third evaporation stage is operated at high temperature to achieve high concentration, then manufacturing precision is improved, but spontaneous decomposition of organic impurities occurs causing pressure shocks and equipment damage
Solution Approach 1:
Organic impurities are preliminarily oxidized in the third evaporation stage before they can undergo spontaneous decomposition, converting them into stable volatile products that eliminate the risk of pressure shocks and equipment damage while maintaining high concentration purity
Solution Approach 2:
The oxidizing agent performs a preliminary anti-action by oxidizing organic impurities before they can decompose spontaneously, preventing the harmful decomposition reaction from occurring and protecting equipment from pressure shocks
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
Prevents fouling and equipment damage by minimizing total organic carbon and avoiding the formation of solid carbonaceous precipitates and spontaneous decomposition, ensuring the production of high-concentration sulfuric acid.
Implementation Method 1
feeding the second concentrated sulfuric acid into a third evaporation stage if step (b) is carried out, or feeding the first concentrated sulfuric acid into the third evaporation stage if step (b) is not carried out, to obtain concentrated sulfuric acid as product; wherein the third evaporation stage is operated at a pressure in a range from 10 to 800 mbar(abs) and a temperature in a range from 180 to 250 °C
Implementation Method 2
an oxidizing agent and/or a precursor of an oxidizing agent is fed into the third evaporation stage... both, fouling due to solid precipitates and spontaneous decomposition of the nitroaromatic compound which may result in pressure shocks and equipment damage, can be avoided
Data Source
Figure 1
AI summary
The invention relates to a process for concentrating diluted sulfuric acid (10) which may comprise at least one nitroaromatic compound and/or nitric acid as impurities, comprising: (a) feeding the diluted sulfuric acid (10) into a first stage (1) in which low boilers are removed by evaporation and/or stripping to obtain a first concentrated sulfuric acid (12); (b) optionally feeding the first concentrated sulfuric acid (12) into a second evaporation stage (2) to obtain a second concentrated sulfuric acid (14); (c) feeding the second concentrated sulfuric (14) acid into a third evaporation stage (3) if step (b) is carried out, or feeding the first concentrated sulfuric acid (12) into the third evaporation stage (3) if step (b) is not carried out, to obtain concentrated sulfuric acid (16) as product, wherein an oxidizing agent (17) and/or a precursor of an oxidizing agent is fed into the third evaporation stage (3).