Supersonic Pyrolysis Quench System for Olefin Yield
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Solution Overview
Problem
Traditional pyrolysis processes are inefficient and costly for converting methane into light olefins like ethylene, and existing supersonic reactor methods face challenges in effectively quenching hot reactor fluids at high temperatures, leading to unwanted product formation and equipment degradation.
Innovation Solution
A supersonic reactor system with a quench section that uses a high heat of vaporization liquid sprayed through nozzles embedded in the wall to rapidly cool the pyrolysis stream, employing a frustum-shaped quench section with a diverging system to slow the vapor flow and a quench fluid that is not reactive with the products, such as water or steam, to control the pyrolysis reaction and protect equipment from extreme conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional pyrolysis processes are used to convert methane into light olefins, then the conversion can be achieved, but the process is inefficient and costly with low yield
Solution Approach 1:
The invention changes the fundamental parameters of the pyrolysis process by using supersonic flow conditions (Mach numbers greater than 1.0) instead of conventional subsonic flow. This supersonic parameter change enables dramatically higher heating rates and shorter residence times, transforming the process efficiency and yield of light olefins from methane conversion
Solution Approach 2:
The invention employs periodic shock waves within the reactor to create oscillating high-temperature zones that periodically pass through the reactant stream. This periodic thermal action enhances the pyrolysis efficiency and product distribution, achieving higher light olefin yields compared to continuous conventional heating
2Productivity
If residence time in heat exchanger tubes is reduced to increase light olefin yield, then productivity improves, but energy consumption increases and byproduct formation increases
Solution Approach 1:
The invention makes the reactant stream rush through the high-temperature zone at supersonic speeds with extremely short residence times (on the order of milliseconds or less). This rapid passage through the reaction zone converts methane to light olefins before significant byproduct formation can occur, achieving high selectivity and yield
Solution Approach 2:
The invention pre-heats the methane feedstock to elevated temperatures before introducing it into the supersonic flow reactor. This preliminary thermal preparation ensures that the methane is ready for rapid pyrolysis upon entering the supersonic zone, improving conversion efficiency and reducing unwanted byproducts
3Productivity
If high temperatures are used in pyrolysis to increase conversion efficiency, then productivity improves, but equipment degradation and unwanted product formation increase
Solution Approach 1:
The invention introduces a diluent gas (such as nitrogen, carbon dioxide, or steam) as an intermediary medium that carries the methane through the high-temperature supersonic flow. This intermediary protects the reactor walls from direct exposure to the harshest conditions while still enabling efficient pyrolysis of the methane feedstock
Solution Approach 2:
The invention employs refractory lining and thermal barrier coatings on the reactor interior surfaces before operation begins. These protective layers are pre-installed to cushion and absorb the thermal stress and chemical erosion from high-temperature supersonic flow, preventing equipment degradation and extending reactor life
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 the yield of acetylene from methane to above 40% and effectively cools the reactor effluent to prevent unwanted product formation, while the quench system's design and materials withstand the harsh operating conditions, improving the overall efficiency and durability of the process.
Implementation Method 1
A liquid is sprayed into the quench section, wherein the liquid has a high heat of vaporization
Implementation Method 2
the liquid is sprayed into the quench section with droplets having a mean diameter less than 500 micrometers
Implementation Method 3
The quench section has a frustum shape, or a conic shape, with a diverging system, such that the flow at the vapor slows
Data Source
AI summary
A quench system and process for cooling high temperature gases is presented. The quench system includes a frustum, or conic, shaped section having an inlet at the smaller end of the quench section and the outlet at the larger end of the quench section. The system includes spray nozzles having openings flush with the wall of the quench section. The process includes spraying a large volume of liquid in small droplets for rapid heat transfer and vaporization of the quench liquid.