Baffle-Free Urea Stripper Shell Vertical Zone Design
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Solution Overview
Problem
Large-scale urea plant strippers experience corrosion issues due to condensate accumulation in the shell space, particularly in vertical zones where the tube bundle diameter is large, leading to hot spots and increased corrosion risk, despite using conventional baffles for heat transfer enhancement.
Innovation Solution
The implementation of a vertical shell-and-tube heat exchanger design without segmental, disc, or donut baffles in the shell space, incorporating a continuous vertical zone for condensate drainage and support structures like grid structures to prevent buckling and vibration, ensuring effective condensate removal and improved heat exchange efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional baffles (segmental, disc, or donut) are installed in the shell space to enhance heat transfer and support tubes, then heat exchange efficiency is improved and tube vibration is reduced, but condensate accumulation occurs in the shell space leading to hot spots and increased corrosion risk
Solution Approach 1:
The invention removes the conventional baffles (segmental, disc, or donut) from the shell space, extracting the element that causes condensate accumulation. The shell space is made free of baffles to eliminate the harmful effect of condensate pooling while maintaining heat exchange through alternative means such as optimized steam flow patterns and tube bundle design.
Solution Approach 2:
The invention transitions from horizontal baffle structures to a vertical dimension approach by optimizing the tube bundle arrangement and steam flow patterns in the vertical shell space. This allows condensate to drain freely vertically while maintaining effective heat transfer through the tube bundle without requiring horizontal baffles.
2Productivity
If a large tube bundle diameter is used to increase heat transfer area, then productivity is improved, but condensate accumulation in the shell space increases leading to hot spots and corrosion
Solution Approach 1:
The invention removes baffles from the shell space, which extracts the cause of condensate accumulation. This allows large tube bundle diameters to be used for increased heat transfer area without the harmful effect of condensate pooling that would otherwise occur with baffle installations.
Solution Approach 2:
Instead of using baffles to control condensate flow, the invention inverts the approach by allowing free vertical drainage in a baffle-free shell space. The condensate management is achieved through gravitational drainage rather than baffle-directed flow, enabling larger tube bundle configurations.
3Productivity
If steam temperature and pressure are increased to enhance stripping efficiency, then productivity is improved, but hot spots occur and corrosion risk increases
Solution Approach 1:
The invention removes baffles from the shell space, eliminating the condensate accumulation that causes hot spots. This allows steam to condense more uniformly on the tube bundle without creating localized hot spots, enabling higher steam temperatures and pressures to be used for improved stripping efficiency without excessive corrosion.
Solution Approach 2:
The invention changes the thermal parameters by allowing higher steam temperatures and pressures while the baffle-free design prevents condensate accumulation. This parameter change is made possible because the absence of baffles eliminates the hot spot formation mechanism, decoupling the relationship between steam temperature and corrosion risk.
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 corrosion risk by preventing condensate accumulation, enhancing local and overall heat exchange efficiency, and maintaining a lower steam temperature and pressure, thereby minimizing hot spots and extending the lifespan of stripper tubes.
Implementation Method 1
the heating fluid is supplied in the shell space and condenses at least in part in the shell space
Implementation Method 2
subjecting the urea synthesis solution to stripping and indirect heat exchange with a gaseous heating fluid in a stripper
Data Source
AI summary
A method is disclosed for stripping in a stripper a urea synthesis solution received from a urea forming process wherein ammonia and CO2 are reacted under urea forming conditions. The shell space of the stripper comprises a continuous vertical zone.