Nitrogen Trifluoride Purification via High-Pressure Vaporization
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Solution Overview
Problem
The challenge lies in efficiently purifying nitrogen trifluoride contaminated with trace amounts of carbon tetrafluoride, as conventional methods struggle due to the similar boiling points and molecular properties of the two substances, making it difficult to achieve ultra-high purity nitrogen trifluoride with carbon tetrafluoride concentrations below 10 ppm.
Innovation Solution
The method involves boiling crude liquid nitrogen trifluoride under a pressure of 35 to 45 atm to vaporize and remove carbon tetrafluoride, using a reactor with an inert gas to facilitate the separation, and optionally employing a packed tower for efficient collection of carbon tetrafluoride vapor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional distillation or absorption process is used, then the process is simple and economical, but the purification precision is insufficient due to similar boiling points of NF3 and CF4
Solution Approach 1:
The patent applies parameter changes by modifying the pressure condition from atmospheric pressure to high pressure (35-45 atm). This pressure parameter change fundamentally alters the vapor-liquid equilibrium relationship between NF3 and CF4, enabling selective vaporization of CF4 at temperatures where NF3 remains liquid, thus achieving high purification precision without complex multi-stage distillation equipment
Solution Approach 2:
The patent utilizes phase transitions by controlling the selective vaporization of CF4 from liquid NF3 under high pressure. By maintaining the system at 35-45 atm and appropriate temperatures, CF4 transitions to vapor phase while NF3 remains in liquid phase, achieving separation based on differential phase behavior rather than relying on small boiling point differences
2Manufacturing precision
If pressure is increased above 45 atm to enhance CF4 removal, then more CF4 is removed, but more NF3 also vaporizes together with CF4
Solution Approach 1:
The patent optimizes the pressure parameter within the specific range of 35-45 atm to achieve the最佳 balance between CF4 removal efficiency and NF3 loss prevention. This parameter optimization ensures that the vapor pressure of CF4 is sufficiently high for effective removal while keeping NF3 vapor pressure low enough to minimize co-vaporization and material loss
3Use of energy by moving object
If pressure is decreased below 35 atm to reduce energy consumption, then energy cost is reduced, but CF4 vaporization is insufficient
Solution Approach 1:
The patent establishes the minimum pressure threshold of 35 atm as the optimal operating condition where sufficient CF4 vaporization occurs while maintaining reasonable energy consumption. Below this pressure, the vapor pressure of CF4 becomes too low to achieve effective separation, making the process energetically inefficient without achieving the desired purification level
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 approach effectively achieves ultra-high purity nitrogen trifluoride with carbon tetrafluoride content reduced to 10 ppm or less, demonstrating a simple and economical solution to the purification challenge.
Implementation Method 1
boiling the crude liquid nitrogen trifluoride under a pressure ranging from 35 to 45 atm, to remove carbon tetrafluoride from the liquid nitrogen trifluoride through vaporization
Implementation Method 2
an inert gas such as helium, nitrogen and a mixture thereof may be fed to the lower part of the reactor and bubbled through the boiling nitrogen trifluoride liquid to expel the gaseous carbon tetrafluoride therefrom
Data Source
AI summary
A highly pure nitrogen trifluoride having a carbon tetrafluoride content of 10 ppm or less can be effectively obtained by boiling crude liquid nitrogen trifluoride having carbon tetrafluoride contaminant under a pressure ranging from 35 to 45 atm, to remove carbon tetrafluoride therefrom through vaporization.