Phosgene Reactor Tube Bundle Arrangement for Pressure Loss Reduction
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Solution Overview
Problem
Large-scale phosgene reactors with diameters greater than 2 or 3.5 meters face challenges with excessive pressure loss and uneven heat transfer coefficients, leading to increased pumping effort and corrosion issues, which limit throughput and capacity.
Innovation Solution
The reactor design features a cylindrical configuration with a bundle of catalyst tubes arranged parallel to each other, where the lateral boundaries of the tube bundle are modified from chords of a circle to arcs of a circle, and the arrangement of baffles ensures consistent pressure loss across flow paths, reducing critical areas with poor heat transfer and minimizing corrosion by equalizing heat transfer coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the reactor diameter is increased to increase capacity, then the throughput is improved, but the pressure loss of the heat transfer medium becomes too large
Solution Approach 1:
The reactor interior is segmented into multiple flow paths by arranging contact tubes in a specific pattern with passage openings. This segmentation divides the single long flow path into multiple shorter parallel paths, reducing the pressure loss in each path while maintaining the overall reactor capacity.
Solution Approach 2:
The contact tubes are arranged in a circular pattern within the reactor, and the flow paths are designed to follow curved trajectories between passage openings. This curved arrangement optimizes the flow distribution and reduces pressure losses compared to straight-line paths, allowing larger reactor diameters without excessive pressure drop.
2Productivity
If the reactor diameter is increased to increase capacity, then the throughput is improved, but the pumping effort becomes too great
Solution Approach 1:
The heat transfer medium flow is segmented into multiple parallel paths through the strategic arrangement of passage openings in baffles. This segmentation reduces the total flow distance and pressure drop, thereby reducing the pumping effort required to circulate the heat transfer medium through large-diameter reactors.
3Temperature
If the heat transfer medium circulation is increased to improve heat transfer, then the heat transfer coefficient is improved, but the pumping effort and pressure loss increase
Solution Approach 1:
The reactor design provides different flow path characteristics for different regions. Areas with poorer heat transfer receive flow paths that promote better heat exchange, while areas with good heat transfer have optimized flow paths. This local optimization improves overall heat transfer efficiency without requiring a proportional increase in total heat transfer medium circulation.
4Temperature
If the heat transfer medium circulation is increased to improve heat transfer, then the heat transfer coefficient is improved, but the pumping effort increases
Solution Approach 1:
The flow path segmentation creates multiple parallel channels that reduce the hydraulic resistance in each channel. This allows for improved heat transfer coefficients through optimized flow distribution without proportionally increasing the pumping effort, as the segmented paths reduce overall pressure drop.
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 reduces pressure loss and heat transfer coefficient disparities, allowing for higher throughput and capacity in large reactors without increasing the heat transfer medium circulation, while minimizing corrosion by optimizing heat dissipation and flow paths.
Implementation Method 1
a liquid heat transfer medium is passed through the contact tubes
Implementation Method 2
baffle plates are installed between the contact tubes, which cause the heat transfer medium to flow transversely onto the contact tubes
Data Source
Figure 1
Figure 2A~2C
Figure 3
AI summary
The invention relates to a reactor (1) for producing phosgene by reacting carbon monoxide and chlorine in the gas phase in the presence of a solid catalyst, which is arranged in the contact tubes (2) of a bundle of contact tubes (2), which are welded into a tube bottom (3) in each case at both ends of said contact tubes, the starting materials being fed at the upper end of the contact tubes (2) and the gaseous reaction mixture being drained at the lower end of the contact tubes (2), through a hood in each case, and having feed and discharge devices for a liquid heat exchanger (6) in the intermediate space (4) between the contact tubes (2), the flow of the heat exchanger (6) in the jacket space (4) between the contact tubes (2) being directed by means of baffle plates (5), which alternately leave open passage openings (7) located opposite each other at the reactor inner wall, the baffle plates (5) comprising circular segment-shaped holes in the passage openings, and the reactor (1) having no tubes in the area of the passage openings (7), characterized in that the heat transfer coefficients at the boundary layer between the catalyst tubes (2) and the heat exchanger (6) are homogenized over each reactor cross-section in that the flow paths of the heat exchanger (6) in each reactor cross-section, in each case measured from the first to the last contact tube (2) in the flow direction of the heat exchanger (6), are equalized through a changed arrangement of the contact tubes (2).