Monocyclic Aromatic Hydrocarbon Production Vibration Control
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Solution Overview
Problem
Conventional methods for producing monocyclic aromatic hydrocarbons using a fluidized-bed system face issues with vibration and heat balance due to the introduction of oil feedstock in a gas-liquid two-phase state, leading to flow resistance changes and problems like coking and corrosion.
Innovation Solution
The method involves pre-heating the oil feedstock to create a two-phase gas-liquid stream, separating it into gas and liquid fractions, and introducing them at different positions within the cracking and reforming reaction apparatus, using a heating device and a catalyst transfer pipe to maintain consistent flow resistance and prevent vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the oil feedstock is heated by exchanging heat with the produced oil to be vaporized before introduction into the reactor, then the vaporization efficiency is improved, but the flow resistance changes repeatedly causing pipe vibration
Solution Approach 1:
The feedstock introduction process is segmented into two separate introduction points: a liquid-phase introduction point and a vapor-phase introduction point. This segmentation allows the liquid and vapor fractions to be introduced separately at different positions, preventing the flow resistance fluctuations that cause vibration while still achieving effective vaporization and reaction.
Solution Approach 2:
The produced oil serves as an intermediary heat transfer medium. It absorbs heat from the reactor and uses it to vaporize the feedstock before introduction. This intermediary approach enables efficient heat recovery while controlling the vaporization process to avoid vibration issues.
2Reliability
If the load of heat exchange is reduced to avoid excessive temperature rise, then pipe vibration is suppressed, but heat recovery becomes insufficient
Solution Approach 1:
By segmenting the feedstock introduction into liquid and vapor phases at different positions, the system can maintain higher heat exchange load without causing vibration. The liquid phase is introduced at one position and the vapor phase at another, distributing the thermal load and preventing the vibration problems associated with single-point two-phase introduction.
Solution Approach 2:
The system changes the physical state parameter of the feedstock from a single two-phase state to separate liquid and vapor phases. This parameter change allows for optimized heat exchange at each introduction point, maximizing heat recovery while avoiding the vibration issues of introducing mixed two-phase flow at a single point.
3Stability of the object's composition
If the oil feedstock is wholly vaporized by pre-heating using a furnace or heat exchanger, then vaporization is complete, but slugs accumulate on the furnace surface causing excessive temperature rise and coking
Solution Approach 1:
The vaporization process is segmented and distributed across two introduction points rather than completing full vaporization in a single furnace. The liquid phase is introduced and partially vaporized, then the vapor phase is separated and introduced at a different position. This prevents slug accumulation on furnace surfaces and the associated coking and corrosion problems.
Solution Approach 2:
The vapor phase is extracted from the heated feedstock stream and separated from the liquid phase. This extracted vapor is then introduced separately at a different position from the liquid phase introduction point. This extraction approach prevents the harmful effects of complete vaporization in a single furnace while still achieving the necessary vaporization for reaction.
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 effectively suppresses vibration and maintains process stability, ensuring efficient heat recovery and reducing issues like coking and corrosion, thereby enhancing the production of monocyclic aromatic hydrocarbons.
Implementation Method 1
heating the oil feedstock in advance before introducing the oil feedstock into the cracking and reforming reaction apparatus and forming a two-phase gas-liquid stream
Implementation Method 2
separating the two-phase gas-liquid stream into a gas fraction and a liquid fraction
Implementation Method 3
heating of the oil feedstock is performed by maintaining a large amount of heat from the cracking and reforming reactor and exchanging heat with produced oil that has been supplied from the distillation tower
Data Source
Figure 1
AI summary
The present invention is related to a producing method of monocyclic aromatic hydrocarbons in which reaction products including monocyclic aromatic hydrocarbons are produced by bringing an oil feedstock and an aromatic production catalyst into contact with each other, the oil feedstock having a 10 volume % distillation temperature of more than or equal to 140°C and a 90 volume % distillation temperature of less than or equal to 380°C, the method including the steps of: introducing the oil feedstock into a cracking and reforming reaction apparatus (10) housing the aromatic production catalyst; bringing the oil feedstock and the aromatic production catalyst into contact with each other at the inside of the cracking and reforming reaction apparatus (10) housing the aromatic production catalyst; heating the oil feedstock in advance before introducing the oil feedstock into the cracking and reforming reaction apparatus (10) and forming a two-phase gas-liquid stream; separating the two-phase gas-liquid stream into a gas fraction and a liquid fraction; and introducing the gas fraction and the liquid fraction at different positions of the cracking and reforming reaction apparatus (10).