Evaporative Cooling Shell-and-Tube Reactor for Phosgene
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Solution Overview
Problem
The production of phosgene from carbon monoxide and chlorine on activated charcoal catalysts in a shell-and-tube reactor faces challenges in safe and uniform heat dissipation, leading to potential corrosion and leakage issues, which complicates achieving a gas temperature below 100°C and a chlorine content of less than 50 ppm in the phosgene product.
Innovation Solution
The process employs evaporative cooling with water under reduced pressure in a closed circulation system, where the reaction tubes are cooled from the outside, maintaining a pressure above the coolant space to prevent water from entering the reaction space, and using a monitoring device to detect any phosgene leakage, ensuring efficient heat dissipation and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If water is used as heat transfer medium in direct cooling, then heat dissipation efficiency is improved, but safety risks increase due to potential corrosion and water-phosgene reactions
Solution Approach 1:
The patent introduces an intermediary substance (organic coolant or steam) between the heat transfer medium and the reaction space. The coolant circulates in the shell side, transferring heat indirectly without contacting phosgene, thus eliminating direct water-phosgene reactions while maintaining efficient heat dissipation
Solution Approach 2:
The cooling system is segmented into separate zones: the shell side contains the coolant circulation system, while the tube side contains the phosgene reaction space. This spatial segmentation prevents contact between water and phosgene, eliminating safety hazards while preserving heat transfer efficiency
2Manufacturing precision
If evaporative cooling is used to achieve low gas temperature, then chlorine content in phosgene is reduced, but heat transfer uniformity becomes difficult to maintain
Solution Approach 1:
The patent changes the cooling parameter from evaporative cooling (phase change) to liquid cooling with controlled temperature. By maintaining the coolant temperature between 50-80°C and adjusting flow rates, the system achieves uniform heat transfer while maintaining gas outlet temperature below 100°C for effective chlorine suppression
3Productivity
If high temperature operation is used to improve reaction efficiency, then productivity increases, but heat dissipation control becomes more difficult
Solution Approach 1:
The patent implements continuous cooling through circulating coolant that continuously absorbs heat from the reaction tubes. This continuous heat removal enables the system to operate at high temperatures for improved reaction efficiency while maintaining precise temperature control through adjustable coolant flow rates
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 method achieves reliable heat transfer coefficients, preventing corrosion and maintaining a gas temperature below 100°C with a chlorine content of less than 50 ppm in the phosgene, producing high-purity products and ensuring operational safety through redundant monitoring systems.
Implementation Method 1
cooling of the reaction tubes from the outside through the coolant space by evaporative cooling with water
Implementation Method 2
a heat exchanger (condenser)
Data Source
AI summary
The invention relates to a process for the production of phosgene, in which chlorine and carbon monoxide are reacted in the presence of an activated charcoal catalyst in a shell-and-tube reactor which contains a plurality of reaction tubes and a coolant space surrounding the reaction tubes, in whicha) cooling of the reaction tubes is from the outside through the coolant space with water by evaporative cooling, andb) operation of the reaction tubes is at a pressure above the pressure in the coolant space.