Tube-to-Tube Sheet Welding for Reduced-Pitch EO Reactors
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Solution Overview
Problem
The fabrication of large-scale ethylene oxide reactors is challenging due to the increasing size and rising costs, with current welding configurations failing to accommodate reduced tube pitch in shell-and-tube heat exchange reactors.
Innovation Solution
Employing a welding material with a tensile strength greater than 600 MPa to create a small welding groove between the tube sheet overlay material and the elongated tubes, allowing for reduced tube pitch and enabling a smaller reactor design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If current welding configurations and materials are used for tube to tube sheet welding, then the welding process is straightforward, but the tube pitch cannot be reduced and the reactor size remains large
Solution Approach 1:
The patent changes the material parameter of the welding material, specifically selecting a welding material with tensile strength greater than 600 MPa. This parameter change enables the use of reduced tube pitch (smaller distance between tube centers) while maintaining adequate welding joint strength, thereby allowing more tubes to be packed into the reactor volume and reducing overall reactor size.
Solution Approach 2:
The patent employs a composite approach by using a specialized high-strength welding material that combines adequate ductility with high tensile strength (>600 MPa). This composite material property profile allows the welding joint to withstand the mechanical stresses imposed by reduced tube pitch configurations while maintaining structural integrity.
2Productivity
If tube pitch is reduced to increase the number of tubes, then reactor volume is reduced, but welding difficulty increases due to limited space and access
Solution Approach 1:
The patent changes the material parameter of the welding material to have high tensile strength (>600 MPa), which compensates for the reduced welding groove size and limited access in reduced tube pitch configurations. This allows smaller welding grooves to be used between the tube sheet overlay material and tubes, enabling reduced tube pitch while maintaining adequate weld strength despite manufacturing challenges.
3Volume of moving object
If high tensile strength welding material is used to enable reduced tube pitch, then reactor size is reduced, but welding material cost increases
Solution Approach 1:
The patent changes the material parameter of the welding material to high tensile strength (>600 MPa) to enable reduced tube pitch and smaller reactor volume. Although the welding material itself is more expensive, the overall cost benefit is achieved through the significant reduction in reactor size and the ability to pack 7-14% more tubes into the same or smaller volume, improving productivity and reducing capital costs.
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 approach enables a 7% to 14% increase in the number of tubes within the reactor, facilitating a more compact reactor design while maintaining structural integrity.
Implementation Method 1
a welding material is located inside the welding groove and is affixed to the outermost sidewall of the elongated tube passing through the third opening
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
Reduced tube pitch within a shell-and-tube heat exchange reactor such as, for example, an EO reactor, is provided by utilizing a welding material that has a high tensile (i.e., a tensile strength of greater than 600 MPa). Reduced tube pitch allows for more elongated tubes (the tubes are filled with a catalyst) to be present in a reactor, and thus a smaller reactor can be manufactured. Notably, the use of a high tensile strength welding material allows the implementation of a small welding groove located between a beveled sidewall of a beveled upper portion of an opening provided in a tube sheet overlay material (that is located atop a tube sheet) and an outermost sidewall of the elongated tube passing through the opening in the tube sheet overlay material.