Transfer Line Permeable Inserts for High Temperature Gas Separation
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Solution Overview
Problem
In ethylene steam cracking processes, a significant amount of capital equipment and energy is used to separate components like H2, CH4, and CO2 from cracked gases, which could be reduced if these gases were separated prior to entering the separation train, but existing technologies do not effectively achieve this at high temperatures.
Innovation Solution
A transfer line with a continuous metal passageway and permeable inserts, such as ceramic or metal inserts with specific porosity and pore sizes, is used to separate H2, CH4, and CO2 from cracked gases before they enter the quench system, allowing for gas tight chambers and ports to withdraw these gases at temperatures from 500°C to 900°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If permeable inserts are added to the transfer line to separate gases, then the separation capability is improved, but the device complexity increases
Solution Approach 1:
The permeable insert is nested within the existing transfer line passageway, creating a compact integrated structure where the separation function is embedded inside the transport component, thus adding functionality without proportionally increasing overall device complexity
Solution Approach 2:
The patent employs permeable inserts with controlled porosity (pore sizes from 0.003 to 0.5 micrometers) made of ceramic or metallic materials that allow selective gas permeation at high temperatures, providing the separation capability through material properties rather than complex mechanical structures
2Productivity
If the transfer line operates at higher temperatures (500-900°C) for better separation, then the separation efficiency is improved, but the material stability requirements worsen
Solution Approach 1:
The transfer line uses composite construction with a metal passageway providing structural integrity and heat resistance, while ceramic or metallic permeable inserts provide the separation function with appropriate thermal stability, combining materials to meet both temperature and stability requirements
Solution Approach 2:
The patent specifies operating temperature ranges (500-900°C) and pore size parameters (0.003 to 0.5 micrometers) that optimize both separation efficiency and material stability, using parameter optimization to balance performance and durability
3Reliability
If permeable inserts with small pore sizes are used to minimize ethane and ethylene diffusion, then the selectivity is improved, but the manufacturing precision requirements worsen
Solution Approach 1:
The patent utilizes inherently porous ceramic or metallic materials with controlled pore structures that provide the required selectivity through material properties rather than requiring precision-manufactured holes, thus achieving small effective pore sizes (0.003 to 0.5 micrometers) with conventional manufacturing tolerances
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 method reduces the load on the separation train by effectively removing H2, CH4, and CO2 from the cracked gases, minimizing the diffusion of ethane and ethylene, and extending the time between decoking the transfer line.
Implementation Method 1
one or more inserts in the passageway permitting the flow of gases through the passageway, the inserts being permeable to at least one of H2, CH4, CO, and CO2 at temperatures from 500° C. to 900° C.
Implementation Method 2
the inserts having a porosity from 10 to 75 percent of pores having a size from 0.003 to 0.5 micrometers
Data Source
AI summary
A transfer line between the outlet of a steam cracker and the inlet for the quench system has metallic or ceramic inserts having a pore size from about 0.001 to about 0.5 microns inside the line forming a gas tight barrier with the inner surface of the line and having a vent for the resulting gas tight pocket are used to separate H2, CH4, CO and CO2 from cracked gases reducing the load on the down-stream separation train of the steam cracker.