Cracked Gas Heat Exchanger Weld-Backed Inlet Connection
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Solution Overview
Problem
Existing heat exchangers with tube connections between uncooled and cooled tubes face challenges in maintaining a fully welded-through weld seam connection between the gas inlet header and the water chamber, which can lead to thermal stress and potential leaks due to differing materials and heat expansion coefficients.
Innovation Solution
The implementation of a weld pool backing ring embedded in a heat-insulating layer within the cooling intermediate space, which is in contact with the tube inner surface of the gas inlet header, ensures a fully welded-through connection by maintaining a defined weld shrinkage and preventing ethylene penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a weld seam connection is made between the gas inlet header and water chamber, then the tubes can be connected, but thermal stress and potential leaks occur due to differing materials and heat expansion coefficients
Solution Approach 1:
A ceramic ring is introduced as an intermediary component between the gas inlet header and water chamber. This ceramic ring serves as a mediator that accommodates thermal expansion differences between the dissimilar materials (steel and cast iron), preventing thermal stress from directly affecting the weld seam connection while maintaining connection integrity and reliability
Solution Approach 2:
The invention changes the material parameter of the connection system by using a ceramic ring instead of direct metal-to-metal connection. The ceramic material has different thermal expansion properties that bridge the gap between steel and cast iron, allowing the connection to withstand thermal cycling without compromising weld seam strength or reliability
2Reliability
If a seal ring is used to prevent cracked gas penetration, then gas leakage is prevented, but the weld seam connection may remain incomplete with gaps
Solution Approach 1:
The sealing function is segmented from the weld seam connection function. The ceramic ring provides sealing by preventing cracked gas penetration through its material properties and fit, while the weld seam connection separately joins the gas inlet header to the water chamber. This segmentation allows each function to be optimized independently, ensuring both sealing reliability and weld seam completeness
3Adaptability or versatility
If different materials with different heat expansion coefficients are used, then the connection can be made between steel gas inlet header and cast iron water chamber, but thermal stress occurs during operation
Solution Approach 1:
The ceramic ring acts as a thermal expansion mediator between the steel gas inlet header and cast iron water chamber. Its intermediate position and material properties allow it to absorb and accommodate the differential thermal expansion, preventing stress transmission to the weld seam connection while maintaining adaptability between different materials
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 configuration ensures a fully welded-through weld seam connection without any remaining gaps, maintaining a defined weld shrinkage and preventing thermal stress and leaks, thereby enhancing the reliability and efficiency of the heat exchanger.
Implementation Method 1
an end piece (22) of the GI tube outer part (13) on an end face (9) of the cooling intermediate space (14) and a WC bottom end face (8) of a water chamber (6) are welded together with the water chamber (6) in full connection without a remaining gap with a fully welded-through weld seam
Implementation Method 2
a weld pool backing ring (16), which is embedded in an inserted insulating layer (15) consisting of a heat-insulating material on the end face (9) of the cooling intermediate space (14) and is in contact with a tube inner surface (10) of a GI tube outer part (13)
Implementation Method 3
The rapid cooling of the cracked gas is carried out in cracked gas columns by means of an indirect transfer of heat from the cracked gas to evaporating water, which is under high pressure
Data Source
AI summary
A cracked gas cooling heat exchanger includes a tube connection between an uncooled tube (1) and a cooled tube (2), having a cooled inner tube (3) enclosed by a jacket tube (4), with a tube intermediate space (5) for flowing cooling medium. A gas inlet header (11) has a GI tube inner part (12) and a GI tube outer part (13) and a cooling space (14) with an insulating layer (15). The GI tube outer part connects via a water chamber (6) to the jacket tube. The GI tube inner part faces the inner tube and is connected on a face (8) of the water chamber. A weld backing ring (16), between an end face (9) of the cooling space and a bottom face (8) of the water chamber, is in the insulating layer of the cooling space, arranged in a turn-out/groove (17) in the insulating layer.