Pyrolytic Reactor Combustion Gas Stream Velocity Transition
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Solution Overview
Problem
Conventional pyrolysis processes for converting methane to high-value olefins like ethylene suffer from low carbon efficiency due to the need to burn methane for heat, resulting in high carbon consumption and low selectivity.
Innovation Solution
A method involving a pyrolytic reactor where a fuel and oxidizer are combusted to create a supersonic combustion gas stream, mixed with methane, and then transitioned to subsonic to form alkenes, followed by catalytic hydrogenation to produce alkenes with improved carbon efficiency and reduced methane burning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If methane is burned to generate heat for pyrolysis, then high temperatures are achieved to convert methane to acetylene, but carbon efficiency decreases and CO2 emissions increase
Solution Approach 1:
The patent converts the harmful effect of methane combustion (carbon loss and CO2 emissions) into a beneficial heat source. The combustion zone deliberately burns a controlled amount of methane to generate the high temperatures needed for pyrolysis, while the resulting hot combustion products are then used to heat the pyrolysis zone, eliminating the need for external fuel and improving overall carbon efficiency.
Solution Approach 2:
The patent merges the combustion process and pyrolysis process into a single integrated system. The combustion zone and pyrolysis zone are coupled such that combustion products directly heat the pyrolysis reaction, combining two previously separate processes (combustion for heat generation and pyrolysis for product formation) into one efficient system.
2Productivity
If methane is burned to achieve high conversion to acetylene, then reaction temperature increases, but selectivity to desired products decreases
Solution Approach 1:
The patent segments the reaction process into distinct zones: a combustion zone for heat generation and a separate pyrolysis zone for selective product formation. This spatial segmentation allows the combustion zone to operate at high temperatures for complete conversion while the pyrolysis zone maintains controlled conditions for high selectivity to acetylene and other desired products, preventing over-cracking and unwanted byproducts.
3Productivity
If conventional pyrolysis processes are used, then methane conversion is achieved, but large amounts of light hydrocarbons are required and carbon efficiency remains low
Solution Approach 1:
The patent implements self-service by using a portion of the methane feedstock itself as the fuel source for generating process heat. Instead of requiring external fuel or large excess of light hydrocarbons, the system burns a controlled amount of the incoming methane to create the thermal energy needed for pyrolysis, making the process self-sufficient and dramatically reducing the quantity of light hydrocarbons required per unit of product.
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 process enhances carbon efficiency and selectivity, producing high-value olefins with lower CO2 emissions and minimized methane burning, while also enabling on-demand hydrogen production.
Implementation Method 1
combusting a fuel and an oxidizer in a combustion zone of a pyrolytic reactor to create a combustion gas stream
Implementation Method 2
transitioning the velocity of the mixed stream from supersonic to subsonic in a reaction zone of the pyrolytic reactor to produce an alkyne
Implementation Method 3
catalytically hydrogenating the alkyne in a hydrogenation zone to produce an alkene
Implementation Method 4
performing pyrolysis of a light hydrocarbon in the presence of oxygen in a reaction zone at a temperature and pressure suitable to produce an alkyne and carbon monoxide
Data Source
Figure 1
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Figure 3~4
AI summary
High efficiency processes for producing olefins, alkynes, and hydrogen co-production from light hydrocarbons are disclosed. In one version, the method includes the steps of combusting hydrogen and oxygen in a combustion zone of a pyrolytic reactor to create a combustion gas stream, transitioning a velocity of the combustion gas stream from subsonic to supersonic in an expansion zone of the pyrolytic reactor, injecting a light hydrocarbon into the supersonic combustion gas stream to create a mixed stream including the light hydrocarbon, transitioning the velocity of the mixed stream from supersonic to subsonic in a reaction zone of the pyrolytic reactor to produce acetylene, and catalytically hydrogenating the acetylene in a hydrogenation zone to produce ethylene. In certain embodiments, the carbon efficiency is improved using methanation techniques.