Solid Particle Bed Grading for Oil Hydrogenation Coke Control
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Solution Overview
Problem
The hydrogenation of oils is hindered by coking and increased pressure drop due to coke powder deposition at the reactor's inlet, leading to a shortened operating cycle and reduced catalyst adsorption capacity.
Innovation Solution
A catalyst grading method is employed, where hydrogenation catalysts with different voidages are packed in a specific manner, forming a grading packing section with columnar reaction cells, alternating or inserted configurations, to enhance sediment dispersion and deposition capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If protective agents with larger voidage are filled in the inlet section to reduce pressure drop increase, then the operating period is prolonged, but the catalyst adsorption capacity is reduced
Solution Approach 1:
The catalyst bed is segmented into multiple sections with different voidage characteristics. The inlet section uses catalyst particles with larger voidage (0.40-0.60) to reduce pressure drop and provide deposition capacity, while downstream sections use catalyst particles with smaller voidage (0.20-0.40) to maintain high adsorption capacity. This segmentation allows each section to perform its specific function optimally without compromising the other.
Solution Approach 2:
Different regions of the catalyst bed are assigned different local qualities in terms of voidage. The inlet region has higher voidage to accommodate sediment deposition and reduce pressure drop increase, while the outlet region has lower voidage to maximize catalytic activity and adsorption capacity. This local differentiation resolves the contradiction by matching voidage characteristics to the specific functional requirements of each zone.
2Quantity of substance
If catalyst particles with smaller voidage are used to increase adsorption capacity, then the pressure drop increases quickly, but the operating cycle is shortened
Solution Approach 1:
The catalyst bed is divided into sections where the inlet section uses high voidage particles to handle sediment deposition, preventing rapid pressure drop increase, while downstream sections use low voidage particles for high adsorption capacity. This segmentation allows the system to maintain both adsorption capacity and operating cycle length.
Solution Approach 2:
The inlet section with larger voidage particles performs a preliminary function of capturing and depositing sediments before the oil stream reaches the main catalytic reaction zone. This preliminary deposition action prevents sediments from quickly clogging the high-capacity downstream catalyst, thereby extending the operating cycle while maintaining adsorption capacity.
3Ease of manufacture
If uniform catalyst packing is used to simplify the structure, then the manufacturing is easier, but the sediment dispersion and deposition capacity is reduced
Solution Approach 1:
The catalyst bed is segmented into sections with different particle voidage characteristics. The inlet section uses particles with larger voidage (0.40-0.60) to enhance sediment deposition capacity, while downstream sections use particles with smaller voidage (0.20-0.40). This segmentation improves deposition capacity while maintaining reasonable manufacturing simplicity through clear zonal differentiation.
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 method slows down the increase in pressure drop and maintains good hydrodesulfurization efficiency by preferentially depositing sediments in areas with larger voidage, thereby prolonging the reactor's operating cycle.
Implementation Method 1
the dispersion and deposition of sediments in the oil can be realized, the adsorption and deposition capacity of the catalyst for sediments can be increased
Implementation Method 2
the adsorption and deposition capacity of the catalyst for sediments can be increased
Data Source
AI summary
A solid particle bed has a sea zone and at least one island zone distributed in the sea zone, and has an upper surface, a lower surface, an axial direction and a radial direction. The island zone extends along the axial direction of the solid particle bed but does not extend to the lower surface, and the voidage of the island zone is 110-300% of the voidage of the sea zone. In the solid particle bed, the oil preferentially enters the packing area with a small voidage through the tail section of the packing area with a large voidage. As the deposition amount increases, the oil gradually changes its way by entering the packing area with a small voidage through the side of the packing area with a large voidage.