Split Cracker Furnace Pyrolysis Oil Injection
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Solution Overview
Problem
The challenge lies in efficiently processing pyrolysis oil (pyoil) in gas furnaces, as it has varying molecular weights and phases, making it difficult to control cracking severity and yield olefins effectively, especially when compared to ethane and propane feeds, leading to fouling and reduced olefin production.
Innovation Solution
A method involving feeding a cracker stream comprising recycle content pyrolysis oil into a split cracker furnace, with separate tubes for pyrolysis oil and C2 to C4 hydrocarbon streams, and controlling steam-to-hydrocarbon ratios to optimize olefin production, while also incorporating a system for atomizing and dispersing pyrolysis oil in the furnace.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pyrolysis oil is fed to a gas furnace operating under ethane/propane cracking conditions, then the furnace can process liquid feedstock, but the cracking severity cannot be controlled and olefin yields are reduced due to overcracking and fouling
Solution Approach 1:
The invention divides the feed system into separate liquid feedlines for pyrolysis oil and gas feedlines for ethane/propane, allowing independent control of each feedstream. This segmentation enables the liquid pyrolysis oil to be introduced without disrupting the gas-phase cracking conditions optimized for ethane/propane, thereby maintaining high olefin yields while processing liquid feedstock.
Solution Approach 2:
The invention uses steam as an intermediary medium to facilitate the introduction of liquid pyrolysis oil into the gas-phase cracking environment. The steam acts as a carrier that vaporizes and disperses the liquid pyrolysis oil droplets throughout the gas feed, enabling homogeneous mixing and controlled cracking while preventing direct liquid injection issues that would cause fouling and uncontrolled reaction.
2Adaptability or versatility
If pyrolysis oil is fed to a gas furnace, then liquid feedstock can be processed, but fouling occurs and residence time control becomes difficult
Solution Approach 1:
The feed system is segmented into separate liquid and gas feedlines, with the liquid pyrolysis oil introduced through dedicated injection points. This prevents liquid feed from disrupting the gas-phase flow patterns and heat distribution, thereby minimizing fouling on furnace tubes while maintaining the ability to process liquid feedstock.
Solution Approach 2:
Steam serves as an intermediary that vaporizes and disperses liquid pyrolysis oil droplets before they reach the cracking zone. This prevents direct contact between liquid oil and furnace tube surfaces, eliminating the fouling mechanism while still enabling the liquid feed to be processed effectively.
3Adaptability or versatility
If pyrolysis oil is fed to a gas furnace, then liquid feedstock can be processed, but cracking severity cannot be controlled due to phase and molecular weight differences
Solution Approach 1:
The invention segments the feed control system into independent liquid and gas feedlines with separate flow control mechanisms. This allows the cracking severity to be controlled by adjusting the gas feed rate while the liquid pyrolysis oil feed rate is controlled independently, enabling precise control of cracking conditions despite the phase and molecular weight differences between feedstocks.
Solution Approach 2:
Steam acts as an intermediary that ensures uniform distribution and vaporization of liquid pyrolysis oil before cracking. This standardized intermediate state allows the cracking severity to be controlled by adjusting steam and gas flow rates rather than dealing directly with the complex variables of liquid pyrolysis oil properties.
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 allows for the effective production of olefins by optimizing the cracking conditions, reducing fouling, and enhancing yield, thereby improving the efficiency and environmental impact of recycling processes.
Implementation Method 1
cracking the first and the second cracker feeds in respective first and second tubes in the cracker furnace to form an olefin-containing effluent stream
Implementation Method 2
controlling steam-to-hydrocarbon ratios to optimize olefin production
Data Source
AI summary
A predominantly C2 to C4 hydrocarbon cracker stream is combined with recycle content pyrolysis oil to form a combined cracker stream and the combined cracker stream is cracked in a cracker furnace to provide an olefin-containing effluent. The r-pyoil can be fed to a first coil while a second cracker feed with none of the r-pyoil or less of the r-pyoil is fed to a second coil, and both are cracked in a cracker furnace to form an olefin-containing effluent stream. Alternatively, the r-pyoil can be fed and distributed across multiple coils along with the non-recycle cracker feed. The furnace can be a gas fed furnace, or split cracker furnace. Further, a first cracker stream with r-pyoil in a first coil can have a lower total molar flow rate than a second cracker stream in a second coil in the same furnace.