Coaxial Flare Stack for Cryogenic CO and Syngas Combustion
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Solution Overview
Problem
Existing high-level flare systems for synthesis gas production plants face limitations in safely and efficiently disposing of gases with varying H₂/CO ratios, often requiring complex support structures and risking flame detachment due to inconsistent gas velocities and thermal stresses.
Innovation Solution
A self-supporting coaxial flare stack design with a stainless steel inner pipe for cryogenic CO gas and a carbon steel outer pipe for synthesis gas, allowing uniform combustion and reduced thermal stresses, eliminating the need for external support structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single flare stack is used for both synthesis gas and cryogenic CO gas, then device complexity is reduced, but thermal stresses and flame detachment risk increase due to inconsistent gas velocities
Solution Approach 1:
The flare stack is segmented into two separate coaxial pipes: an inner pipe for cryogenic CO gas and an outer pipe for synthesis gas. This segmentation allows each gas type to be handled independently with appropriate velocity control, preventing flame detachment while maintaining a unified overall structure.
Solution Approach 2:
The inner pipe is nested within the outer pipe, creating a coaxial configuration where the inner pipe carries cryogenic CO gas and the outer pipe carries synthesis gas. This nesting approach enables separate flow paths within a single integrated flare stack structure, reducing overall device complexity while maintaining combustion stability.
2Object-affected harmful factors
If different materials are used for inner and outer pipes, then corrosion resistance is improved, but thermal stresses increase due to differential expansion
Solution Approach 1:
Different material properties are assigned to different parts of the flare stack: the inner pipe is made of stainless steel for superior corrosion resistance against cryogenic CO gas, while the outer pipe uses carbon steel adequate for synthesis gas. This local differentiation optimizes corrosion resistance where needed while managing thermal stress through appropriate material selection in each zone.
Solution Approach 2:
The design accounts for differential thermal expansion between the stainless steel inner pipe and carbon steel outer pipe by allowing independent expansion movements. The coaxial configuration and flexible joint design accommodate the different expansion rates of the two materials, preventing excessive thermal stress buildup.
3Ease of manufacture
If a self-supporting design is used, then investment costs are reduced, but structural stability may be compromised
Solution Approach 1:
The inner and outer pipes are merged into a single integrated coaxial structure that supports itself. The combined structure leverages the strength of both pipes working together, eliminating the need for external support frameworks while reducing installation complexity and investment costs.
Solution Approach 2:
The flare stack employs a composite structure combining stainless steel and carbon steel pipes in a coaxial arrangement. This composite design provides enhanced structural stability through the synergistic effect of the two materials, allowing the system to support itself without external frameworks while maintaining the necessary mechanical strength.
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
Enables safe and efficient thermal disposal of gases with wide H₂/CO ratios without external support, reducing investment costs and preventing flame detachment, while ensuring uniform combustion and reduced corrosion.
Implementation Method 1
a first exhaust pipe (2) made of a second material, in this case unalloyed or low-alloy steel, for example carbon steel, and a second exhaust pipe (5) made of a third material, in this case a high-alloy steel, for example a low-temperature resistant stainless steel
Implementation Method 2
a common burner (8) for simultaneous combustion of both exhaust gases
Data Source
Figure 1
AI summary
The invention relates to a flare system in a synthesis gas production plant for the thermal disposal of exhaust gases generated during synthesis gas production and/or synthesis gas processing, containing at least two different concentrations of carbon monoxide (CO), in particular for the simultaneous flaring or combustion of warm synthesis gas and also cryogenic, extremely cold carbon monoxide. According to the invention, the flare system comprises: (a) a first exhaust pipe made of a first material, arranged perpendicular to the horizontal, and a supply line for exhaust gas with a first CO concentration to the first exhaust pipe; (b) a second exhaust pipe made of a second material, arranged perpendicular to the horizontal, and a supply line for exhaust gas with a second CO concentration to the second exhaust pipe; (c) wherein the first and the second exhaust pipes are arranged coaxially and open into a common burner at their upper ends.