Supersonic Reactor Methane Pyrolysis with Methanation Recycling
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Solution Overview
Problem
Current methods for converting methane to acetylene or ethylene are inefficient and costly due to high compression costs and low yield, with traditional pyrolysis systems being ineffective for methane conversion, leading to increased energy consumption and CO2 acid gas waste.
Innovation Solution
A process integrating a supersonic reactor with a methanation reactor and a quench unit, where methane is pyrolyzed, quenched, and then recycled with hydrogenation and solvent separation to optimize methane conversion and reduce acid gas production, using a methanation reactor to convert excess carbon oxides back into methane for recycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional pyrolysis systems are used to convert methane to acetylene or ethylene, then the process can operate with simple equipment, but the conversion efficiency is low and compression costs are high
Solution Approach 1:
The process is divided into distinct functional segments: a supersonic reactor for high-temperature pyrolysis, a quench unit for rapid cooling, and a methanation reactor for CO/CO2 conversion. Each segment performs a specific function that contributes to overall efficiency, with the supersonic reactor achieving high conversion rates and the methanation reactor recovering valuable methane from waste streams
Solution Approach 2:
The patent combines the supersonic reactor, quench unit, and methanation reactor into an integrated system where the output of one unit becomes the input of the next. The quench unit rapidly cools the pyrolysis effluent to preserve product yield, while the methanation reactor converts CO and CO2 back to methane that can be recycled to the supersonic reactor, creating a closed-loop system that maximizes methane utilization
2Productivity
If higher temperatures and short residence times are used to increase acetylene yield from methane, then the conversion efficiency improves, but compression costs and energy consumption increase
Solution Approach 1:
The supersonic reactor pre-heats the methane feed to extremely high temperatures (2000-3500°C) before the actual pyrolysis reaction occurs. This preliminary heating in a controlled environment ensures that the methane is ready for rapid conversion when it enters the reaction zone, achieving high yields without requiring sustained high-energy input throughout the entire process
Solution Approach 2:
The process utilizes extremely short residence times (milliseconds) in the supersonic reactor, allowing the pyrolysis reaction to complete rapidly at high temperatures. The quench unit then immediately cools the effluent to freeze the reaction products, preventing further energy consumption and preserving the high yield achieved during the brief high-temperature exposure
3Ease of operation
If CO and CO2 are carried through compressors in the conversion process, then the complete gas stream is processed, but compression costs increase and CO2 acid gas waste is produced
Solution Approach 1:
The methanation reactor selectively extracts and converts CO and CO2 from the pyrolysis effluent by reacting them with hydrogen to form methane. This extraction removes the problematic acid gases from the stream that would otherwise require expensive compression and disposal, while simultaneously generating valuable methane that can be recycled to the supersonic reactor
Solution Approach 2:
The methanation reactor converts the harmful CO and CO2 byproducts into beneficial methane fuel. By catalyzing the reaction between CO/CO2 and hydrogen, the system transforms waste acid gases into a valuable feedstock that can be recycled to the supersonic reactor, turning a disposal cost into a resource recovery opportunity
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 increases methane conversion efficiency, reduces compression costs, and improves overall process economics by achieving higher yields of acetylene or ethylene compared to traditional methods, while minimizing CO2 production and optimizing compression profiles.
Implementation Method 1
pyrolyzing a feed stream in a pyrolysis zone of a supersonic reactor to produce a pyrolysis zone effluent stream
Implementation Method 2
The pyrolysis zone effluent stream is then quenched in a quenching zone to produce a quenched stream
Implementation Method 3
At least a portion of the carbon oxide of the net gas stream is converted in a methanation reactor into a methanation reactor effluent stream comprising primarily methane
Data Source
AI summary
A process for producing acetylene, ethylene, or both is disclosed. The process includes combusting a fuel stream to produce a combustion gas effluent stream and pyrolyzing a feed stream in a pyrolysis zone in the presence of the combustion gas effluent stream to produce a pyrolysis zone effluent stream which is further quenched and compressed. The compressed quenched stream is separated in a solvent separation column to produce a net gas stream comprising hydrogen, methane, and at least one carbon oxide and a product stream. A portion of the carbon oxide of the net gas stream is converted into methane in a methanation reactor and a reactor effluent stream is sent to an amine scrubber where carbon dioxide is removed and a methane containing stream is generated as an effluent. The methane containing stream is then recycled to the pyrolysis zone of the supersonic reactor.