Hydrogen Chloride Isolation via Depressurization and Compression
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Solution Overview
Problem
Current processes for producing isocyanates generate hydrogen chloride at pressures lower than desired for subsequent uses, requiring costly apparatus and energy for compression and purification, while also containing impurities that need to be removed.
Innovation Solution
A process involving single-stage or multistage depressurization of the crude product from phosgenation to separate hydrogen chloride into gaseous and liquid streams, followed by compression and purification in a distillation column to achieve hydrogen chloride at the desired pressure and purity for subsequent uses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If hydrogen chloride is isolated at low pressure from phosgenation crude product, then the isolation process is simpler and requires less energy, but the hydrogen chloride cannot be directly used for subsequent reactions requiring higher pressure
Solution Approach 1:
The patent divides the hydrogen chloride isolation process into two separate streams: a first stream isolated at low pressure (5-20 bar) and a second stream isolated at high pressure (50-100 bar). This segmentation allows each stream to be optimized for its specific use, avoiding the need to compress the entire hydrogen chloride stream, thereby reducing energy consumption while maintaining pressure adaptability for different subsequent reactions.
Solution Approach 2:
The patent changes the pressure parameter during the isolation process by operating the first isolation step at low pressure (5-20 bar) and the second isolation step at high pressure (50-100 bar). This parameter change enables the hydrogen chloride to be obtained at the required pressure for subsequent uses without requiring additional compression energy.
2Manufacturing precision
If hydrogen chloride is isolated through multiple compression and purification steps, then the hydrogen chloride achieves desired pressure and purity, but the process complexity and apparatus requirements increase
Solution Approach 1:
The patent segments the hydrogen chloride isolation into two parallel streams with different pressure requirements. The first stream (5-20 bar) can be used for applications requiring lower pressure, while the second stream (50-100 bar) provides high-pressure hydrogen chloride. This segmentation reduces the need for multiple compression steps and complex apparatus, as each stream is isolated at its target pressure directly from the crude product.
Solution Approach 2:
The patent employs different pressure parameters for the two isolation steps: low pressure (5-20 bar) for the first stream and high pressure (50-100 bar) for the second stream. This parameter differentiation simplifies the overall process by avoiding sequential compression steps and reduces apparatus complexity while achieving the desired purity and pressure for different applications.
3Adaptability or versatility
If the entire hydrogen chloride stream is compressed to high pressure, then all hydrogen chloride can be used for high-pressure reactions, but energy consumption and process cost increase
Solution Approach 1:
The patent segments the hydrogen chloride stream into two portions based on pressure requirements: a first stream isolated at low pressure (5-20 bar) for applications that do not require high pressure, and a second stream isolated at high pressure (50-100 bar) for high-pressure reactions. This segmentation avoids the need to compress the entire stream, significantly reducing compression energy consumption while maintaining pressure flexibility for different reactions.
Solution Approach 2:
Instead of compressing the entire hydrogen chloride stream to high pressure (excessive action), the patent applies compression only where necessary by isolating the second stream at high pressure directly from the crude product. This partial action approach reduces unnecessary compression energy while still providing high-pressure hydrogen chloride when needed for specific reactions.
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 efficiently provides hydrogen chloride at the required pressure and purity, reducing the need for extensive compression and apparatus, and effectively removes impurities, making it suitable for uses like the Deacon process or ethylene dichloride production.
Implementation Method 1
single-stage or multistage depressurization of the crude product from the phosgenation (40), which is under the pressure pR, to a pressure pE≥pF
Implementation Method 2
compression of the stream (80) containing phosgene and hydrogen chloride and also optionally a subordinate amount of the solvent to a pressure pV>pF
Implementation Method 3
purification, preferably in a distillation column, of the stream (60) containing hydrogen chloride and of the compressed stream (90) containing phosgene and hydrogen chloride
Data Source
AI summary
The invention relates to an improved process for making available the coproduct hydrogen chloride obtained in the preparation of an isocyanate by phosgenation of the corresponding amine for a desired subsequent use (i.e. a chemical reaction), in which part of the total hydrogen chloride obtained is isolated in gaseous form at a pressure which is higher than the pressure desired for the subsequent use of the hydrogen chloride by lowering the pressure of the crude product from the phosgenation and the remaining part of the total hydrogen chloride obtained is separated off at a pressure lower than that desired for the subsequent use from the liquid crude product from the phosgenation remaining after lowering of the pressure and is subsequently compressed to a pressure which is higher than that desired for the subsequent use, and in which the two hydrogen chloride streams obtained in this way are, preferably together after having been combined, purified so as to give a purified hydrogen chloride at a pressure which is higher than the pressure desired for the subsequent use.