Nitrosyl Sulfuric Acid Decomposition for High-Purity Acid Recovery
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Solution Overview
Problem
Current methods for recycling nitrosyl sulfuric acid/sulfuric acid mixtures are inefficient in removing nitrogen oxides, leading to contamination of sulfuric acid products and imbalances in acid concentrations, especially when dealing with high nitrogen content waste gases.
Innovation Solution
A process involving the addition of dilute nitric acid to decompose nitrosyl sulfuric acid, followed by steam stripping to separate and concentrate sulfuric acid, and subsequent condensation to obtain high-purity nitric acid, while using medium-pressure absorption to manage nitrogen oxides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If nitrosyl sulfuric acid is decomposed by diluting with water to less than 60 or 70 wt.-% sulfuric acid, then decomposition is achieved, but the concentration of product sulfuric acid is limited and nitric acid contaminates the product
Solution Approach 1:
The invention changes the concentration parameter of nitric acid from the conventional less than 60-70 wt.-% to a specific range of 65-95 wt.-%, which fundamentally alters the decomposition behavior and allows obtaining high-concentration sulfuric acid (98 wt.-%) as product while preventing nitric acid contamination
Solution Approach 2:
The invention uses concentrated nitric acid (65-95 wt.-%) as a substitute for water dilution, copying the decomposition function but with superior results - achieving both complete decomposition and high product concentration without the drawbacks of water dilution method
2Object-generated harmful factors
If nitrogen oxides are removed by catalytic or non-catalytic reduction with reducing agents, then nitrogen oxide removal is achieved, but the process is only economically viable for low nitrogen concentrations
Solution Approach 1:
The invention extracts nitrogen oxides from nitrosyl sulfuric acid through decomposition and phase separation, obtaining them as a distinct gaseous phase that can be separately treated, making the process economically viable for high nitrogen concentrations (20-40 g N/L or above)
Solution Approach 2:
The invention converts the harmful nitrosyl sulfuric acid containing high nitrogen content into beneficial products: purified sulfuric acid (98 wt.-%) and concentrated nitric acid (65-95 wt.-%), turning a waste disposal problem into a value-added production process
3Productivity
If mixed acid is transferred to product acid, then sulfuric acid production is maintained, but denitrification is required to achieve required acid qualities
Solution Approach 1:
The invention segments the mixed acid into two distinct phases through controlled decomposition: purified sulfuric acid (98 wt.-%) and concentrated nitric acid (65-95 wt.-%), eliminating the need for complex denitrification processes and allowing direct transfer to product storage
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 achieves complete decomposition of nitrosyl sulfuric acid, producing sulfuric and nitric acids with low residual nitrogen content and high concentrations, reducing operational costs and simplifying the process.
Implementation Method 1
adding (i) a dilute nitric acid containing less than 70 wt.-% nitric acid to (ii) the mixed acid comprising nitrosyl sulfuric acid and sulfuric acid to effect the decomposition of the nitrosyl sulfuric acid
Implementation Method 2
adding steam to the sulfuric acid and nitric acid-comprising liquid phase obtained in step a) to separate (v) a purified sulfuric acid, and evaporate (vi) a mixture of concentrated nitric acid and nitrogen oxides
Implementation Method 3
cooling the gas phase comprising the nitrogen oxides obtained in step a) and the mixture of nitric acid and nitrogen oxides obtained in step b) in order to separately obtain (vii) a purified nitric acid condensate and nitrogen oxides
Implementation Method 4
absorbing nitrogen oxides in water to obtain dilute nitric acid
Data Source
AI summary
A process for recycling of a mixed acid containing nitrosyl sulfuric acid and sulfuric acid to obtain nitric acid and sulfuric acid, the process including adding (i) a dilute nitric acid to (ii) the mixed acid comprising nitrosyl sulfuric acid and sulfuric acid to effect the decomposition of the nitrosyl sulfuric acid and to obtain (iii) a liquid phase and (iv) a gaseous phase, adding steam to the liquid phase to separate (v) a purified sulfuric acid, and evaporate (vi) a mixture of concentrated nitric acid and nitrogen oxides, cooling the gas phase and the mixture of nitric acid and nitrogen oxides in order to separately obtain (vii) a purified nitric acid condensate and (viii) nitrogen oxides, absorbing nitrogen oxides (viii) in water to obtain dilute nitric acid (ix), and optionally, introducing at least part of the obtained dilute nitric acid (ix) into the process.