Steam Reformer Inert Contact Zone to Prevent Catalyst Coking
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Solution Overview
Problem
Coke formation and deposition onto steam reforming catalysts during the steam reforming of methane and carbon monoxide-containing feed gases lead to increased pressure drop and decreased catalyst activity, reducing hydrogen production efficiency, and existing methods to prevent coke formation are either costly or require significant unit revamps.
Innovation Solution
Contacting the reaction mixture of methane, carbon monoxide, and steam with an inert material in the heated zone of the steam reformer before it reaches the steam reforming catalyst, quickly heating it to 540°C without coke formation, ensuring effective steam reforming reactions occur.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If additional steam is added to prevent coke formation, then coke deposition is reduced, but hydrogen production decreases due to hydraulic limitations and energy costs
Solution Approach 1:
An inert material is introduced as an intermediary substance between the feed gas/steam mixture and the steam reforming catalyst. This inert material serves as a heat transfer medium that rapidly heats the reaction mixture to temperatures above 500°C, preventing coke formation without requiring additional steam. The inert material absorbs heat from external sources and transfers it to the reaction mixture, acting as a thermal mediator that solves the contradiction between preventing coke and maintaining hydrogen production capacity.
2Object-affected harmful factors
If the reaction mixture is preheated to above 540°C by external heating means, then coke formation is prevented, but equipment complexity and investment costs increase substantially
Solution Approach 1:
The inert material serves as a thermal intermediary that can be heated externally and then used to rapidly heat the reaction mixture. This approach requires minimal modification to existing equipment - the inert material can be heated in the same reformer furnace or by simple external heaters, and then introduced into the reaction zone. This is much simpler than installing complex preheating systems, convection section coils, or additional heat exchangers, thus resolving the contradiction between preventing coke and avoiding substantial equipment revamps.
Solution Approach 2:
The invention changes the thermal parameters of the reaction mixture by introducing a material with different heat transfer characteristics. The inert material has high heat capacity and can be rapidly heated to high temperatures, then transfers this heat to the reaction mixture, causing a rapid temperature increase from below 500°C to above 540°C. This parameter change approach prevents coke formation without requiring complex continuous preheating systems.
3Use of energy by moving object
If the reaction mixture temperature is kept below 500°C before catalyst contact, then energy consumption is reduced, but coke deposits onto the catalyst reducing activity
Solution Approach 1:
The inert material enables the reaction mixture to rapidly skip through the problematic temperature range (below 500°C) where coke formation occurs. By introducing preheated inert material, the mixture temperature jumps quickly from below 500°C to above 540°C, rapidly passing through the coke-forming temperature zone. This rushing through approach minimizes the time the mixture spends at temperatures that cause coke deposition, thus protecting catalyst activity while minimizing energy consumption compared to continuous preheating.
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
Prevents coke deposition while optimizing hydrogen production and equipment use by ensuring the steam reforming catalyst is active at the optimal temperature, thereby enhancing overall hydrogen yield and purity.
Implementation Method 1
the reaction mixture having a temperature below 500°C is quickly heated to a temperature of at least 540°C whilst no coke is formed and deposited onto active steam reforming catalyst
Implementation Method 2
a methane (CH4) comprising feed gas is reacted with steam in the presence of a suitable steam reforming catalyst at an operating pressure of at least 15 bara
Implementation Method 3
The steam reforming reaction is: CH4 + H2O → CO + 3H2
Implementation Method 4
the carbon monoxide (CO) formed is typically converted with steam via the water gas shift reaction into carbon dioxide (CO2) and hydrogen: CO + H2O → CO2 + H2
Implementation Method 5
Predominant carbon forming reactions in such case are the Boudouard reaction: 2CO → C + CO2
Implementation Method 6
the CO reduction reaction: CO + H2 → C + H2O
Data Source
AI summary
Process for the preparation of hydrogen by reacting a feed gas comprising methane and carbon monoxide with steam in the presence of a steam reforming catalyst at a pressure of at least 15 bara in the heated zone of a steam reformer to obtain a raw hydrogen containing product stream, wherein (a) the feed gas is mixed with the steam before entering the steam reformer resulting in a reaction mixture of the feed gas and steam having a temperature below 540ºC; and (b) the reaction mixture obtained in step (a) is fed into the heated zone of the steam reformer where it is first contacted with an inert material before it is contacted with the steam reforming catalyst.