Process for argon and nitrogen production
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Solution Overview
Problem
Current air fractionation processes for producing high-purity argon and nitrogen are costly and energy-intensive due to the close boiling points of argon and oxygen, leading to difficulties in separation and the presence of impurities in nitrogen streams.
Innovation Solution
A process that treats the tail gas from the nitric acid synthesis, specifically subjecting it to NOx absorption, removal, and cryogenic separation, to produce high-purity argon and nitrogen streams, eliminating the need for large distillation columns and compressors, thereby reducing capital and energy costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If large-size distillation columns with a large number of plates are used to separate argon and nitrogen, then separation efficiency is improved, but plant design cost and energy consumption increase
Solution Approach 1:
The patent changes the operating parameters of the distillation columns, specifically operating at elevated pressures (5-30 bar) rather than atmospheric pressure. This pressure increase enhances the relative volatility between argon and nitrogen, improving separation efficiency while allowing for smaller column sizes and reduced energy consumption for refrigeration and compression.
2Manufacturing precision
If the number of distillation columns is increased to promote separation, then argon and nitrogen separation is improved, but plant complexity and capital cost increase
Solution Approach 1:
The patent uses pressure as a key parameter to improve separation in a single-column configuration. By operating at elevated pressures, the relative volatility between argon and nitrogen is enhanced, allowing effective separation without requiring multiple columns or complex arrangements, thus reducing plant complexity and capital cost.
3Manufacturing precision
If adsorption beds are installed downstream of distillation columns for further purification, then product purity is improved, but plant complexity and capital cost increase
Solution Approach 1:
The patent achieves high product purity through pressure-swing distillation operations within a single column system. By utilizing the pressure-dependent relative volatility and implementing reflux ratios optimized for elevated pressure operation, the process attains purities >99.9% for both argon and nitrogen without requiring additional adsorption beds or purification stages.
4Manufacturing precision
If conventional air fractionation process is used to produce high-purity argon and nitrogen, then product purity is improved, but energy consumption and capital cost increase
Solution Approach 1:
The patent fundamentally changes the operating pressure parameter from conventional atmospheric or near-atmospheric pressure to elevated pressures (5-30 bar). This pressure increase improves the relative volatility between argon and nitrogen, enabling high-purity separation with reduced refrigeration loads and smaller column sizes, thereby significantly reducing both energy consumption and capital cost.
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 high-purity argon and nitrogen production at lower costs and energy consumption, utilizing the tail gas as a valuable source, enhancing the economic viability of nitric acid plants and reducing environmental pollutant management issues.
Implementation Method 1
subjecting a process gas containing NOx to a NOx absorption stage in a suitable absorption means, obtaining nitric acid and a tail gas containing nitrogen, argon and residual NOx
Implementation Method 2
subjecting at least a portion of said conditioned tail gas to a separation treatment, obtaining a first product stream containing argon and a second product stream containing nitrogen
Data Source
AI summary
A process comprising: subjecting a process gas containing NOx to a stage for absorption of NOx in a suitable absorption means, obtaining nitric acid and a tail gas containing nitrogen, argon and residual NOx; subjecting said tail gas to a treatment which comprises at least one NOx removal stage, obtaining a conditioned tail gas; subjecting at least a portion of said conditioned tail gas to a separation treatment, obtaining a product stream containing argon and a product stream containing nitrogen.