Phosgene Reactor Annular Cooling Plate Design
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Solution Overview
Problem
Existing phosgene production methods face challenges in efficiently cooling large-scale reactors with a high number of reaction tubes under free convection, particularly in the area immediately above the lower tube bottom, where heat dissipation is critical and the risk of chlorine-induced reactions is high.
Innovation Solution
A device featuring a tube bundle reactor with an annular plate framing the tube bundle, creating an inner annular space for liquid cooling fluid and an outer space for flow connection, with a downpipe for liquid cooling fluid and a steam belt for gaseous fluid, allowing for efficient heat transfer and dissipation without the need for forced convection, reducing the risk of accidents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large number of reaction tubes are used in a tube bundle reactor for high-capacity phosgene production, then productivity is improved, but the difficulty of cooling uniform heat dissipation increases
Solution Approach 1:
The cooling system is segmented into multiple independent channels: an inner annular space for liquid cooling fluid and an outer annular space for gaseous cooling fluid, with separate inlet and outlet openings. This segmentation allows each channel to be optimized independently for heat dissipation, enabling effective cooling of large numbers of reaction tubes without excessive system complexity.
Solution Approach 2:
The cooling approach transitions from single-phase liquid cooling to two-phase cooling by introducing gaseous cooling fluid in the outer annular space. This dimensional change in the cooling medium state enables enhanced heat transfer capacity, allowing high-capacity reactors with many tubes to be cooled effectively.
2Power
If forced convection is used for cooling the reaction tubes, then heat dissipation efficiency is improved, but the risk of accidents increases
Solution Approach 1:
The cooling system operates using natural convection where the cooling fluid circulates automatically through the annular spaces driven by temperature-induced density differences. This self-service mechanism eliminates the need for external pumps or forced convection systems, reducing mechanical complexity and accident risks while maintaining effective heat dissipation.
Solution Approach 2:
The patent replaces mechanical forced convection systems with a passive thermal convection system. The cooling fluid circulation is driven by thermal forces rather than mechanical pumps, substituting a simpler, safer physical mechanism for a more complex mechanical one, thereby reducing accident potential.
3Reliability
If the cooling fluid pressure is lowered to prevent corrosion in the reaction chamber, then reliability is improved, but the heat dissipation capacity decreases
Solution Approach 1:
The cooling system is divided into two separate annular spaces with different pressure regimes: the inner space maintains lower pressure to prevent corrosion in the reaction chamber, while the outer space can operate at higher pressure for enhanced cooling capacity. This segmentation allows each zone to operate under its optimal pressure conditions independently.
Solution Approach 2:
The annular plate acts as an intermediary structure separating the inner and outer cooling spaces. It allows thermal energy transfer between the two spaces while maintaining pressure differentiation, enabling the system to achieve both corrosion protection and high cooling capacity through the coordinated action of both cooling zones.
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 design enables effective cooling of a large number of reaction tubes, even in high-capacity reactors, by ensuring uniform and efficient heat dissipation, reducing the risk of accidents and maintaining safety, especially with highly toxic phosgene production.
Implementation Method 1
a cooling fluid circulation device, in particular designed in such a way that this can convey the cooling fluid from the lower tube bottom through the inner annular space in the direction of the upper tube bottom
Implementation Method 2
This is achieved by guiding a cooling medium around the reaction tubes in forced convection or partially evaporating around the tubes in natural convection
Implementation Method 3
The reaction between CO and chlorine starts at the catalyst at about 40 - 50 ° C, whereby the temperature in the pipes rises to about 600 ° C
Data Source
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AI summary
The invention relates to a device (R) for producing phosgene by reacting chlorine and carbon monoxide in the presence of a fixed-bed catalyst, comprising a) a tube bundle, which is arranged inside a reactor jacket (4) and which has a plurality of reaction tubes (3), which are arranged substantially parallel to each other and which extend from a lower tube sheet (1) to an upper tube sheet (2), and b) a coolant space for a cooling fluid, which coolant space surrounds the reaction tubes (3) and is defined by the lower tube sheet (1), the upper tube sheet (2), and the reactor jacket (4), wherein the device is characterized in that the tube bundle is enclosed by an annular-space sheet (7), which defines an inner annular space (12) for the passage of the cooling fluid and which is arranged at a distance from both the lower tube sheet (1) and the upper tube sheet (2), wherein an outer annular space (13) for feeding liquid cooling fluid through is formed between the annular-space sheet (7) and the reactor jacket (4), which outer annular space is in fluid connection with the inner annular space (12). The invention further relates to a method for producing phosgene by means of such a device.