Catalyst Tubes with Foam Supports for H2S Cracking
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Solution Overview
Problem
Conventional regenerative catalyst tubes face issues with limited heat exchange efficiency, mechanical stress due to differential sliding during startup and shutdown, and difficulties in catalyst loading and unloading, particularly when dealing with high-temperature product gases and catalysts supported on conventional materials.
Innovation Solution
The use of catalysts supported on metallic or ceramic foams, which reduce friction with tube walls and utilize preformed structures to enhance heat transfer and simplify loading/unloading operations, along with a dual catalyst bed configuration to optimize heat exchange and quenching of reaction products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional catalyst particles are used in regenerative catalyst tubes, then heat exchange surface area is increased, but friction with tube walls during startup and shutdown causes mechanical stress and catalyst breaking
Solution Approach 1:
The patent applies porous foam structures (metallic or ceramic) as catalyst supports instead of conventional solid particles. These foam materials provide high surface area for heat exchange while their porous nature and flexible structure reduce friction with the tube walls during thermal expansion and contraction cycles, thereby reducing mechanical stress and catalyst breaking.
Solution Approach 2:
The patent uses composite structures combining catalyst particles with foam supports (metallic or ceramic). This composite approach allows the catalyst to be distributed on a flexible foam matrix that can accommodate thermal expansion differences between the riser and catalyst tube, reducing mechanical stress while maintaining adequate heat exchange surface area.
2Force
If catalyst supported on metallic or ceramic foams is used, then friction with tube walls is reduced, but heat transfer rate may be decreased due to lower surface area
Solution Approach 1:
The porous foam structure provides a three-dimensional network of interconnected pores that significantly increases the internal surface area available for heat transfer. Despite the reduced friction with tube walls, the extensive internal surface area of the foam structure compensates by providing adequate heat exchange capacity between the catalyst and the surrounding fluid.
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 solution significantly enhances heat transfer rates, reduces mechanical stress and pressure drops, and facilitates easier catalyst handling by minimizing friction and utilizing dead space for additional catalyst beds, thereby improving the efficiency and reliability of hydrogen and sulfur production in regenerative catalyst tubes.
Implementation Method 1
C.Y.Zhao, T.J-Lu and H.P.Hodson have presented in 2004 results from experimental measurements on radiative transfer in FeCrAIY foams having high porosity and different cells size
Implementation Method 2
Y.Peng and J.T.Richardson have presented in 2004 the properties of ceramic foam as catalyst supports and reported experimental data showing that the catalyst on ceramic foam support shows increased overall heat transfer
Implementation Method 3
The H2S is normally produced in the refineries were the products are desulfurized by hydrotreting with the H2. The H2S is then burned to produce sulfur. The proposed catalyst tube will permit to perform the cracking of the H2S according to the above reaction and other endothermal catalytic reactions
Implementation Method 4
the hydrogen sulphide (H 2 S) at high temperature will form H2 and S in presence of a catalyst according to reaction
Data Source
Figure 1~2
Figure 3~4b
Figure 5
AI summary
A catalyst tube for endothermic reactions suitable for high temperature endothermic reactions performed at temperature from 300 to 12000C for production of hydrogen and sulphur by the cracking of hydrogen sulphide or other products, comprises two feedstock patterns ad one product pattern, coaxial one to another, said pattern being obtained through three concentric tubes which define a first annular space wherein a catalyst bed is installed, an inner annulus where the reaction product is collected and a central circular tube wherein a second catalyst bed is installed in order to have the catalyst on both external and internal side of said annulus. The catalyst on the external side of said annulus is supported on metallic or ceramic foams having suitable form to avoid the problems due to the friction on the walls of the used conventional catalysts and to get an easy unloading and loading in the catalyst tubes.