Methanation Reactor Staged Cooling for Nickel Carbonyl Prevention
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Solution Overview
Problem
Current methanation methods face challenges in maintaining low reaction temperatures to maximize methane production while avoiding catalyst damage from nickel carbonyl formation, as high temperatures increase equilibrium methane concentration and require significant equipment for CO conversion stages.
Innovation Solution
The method involves dividing the catalyst bed into multiple methanation stages with incremental synthesis gas flow and direct cooling, using a CO conversion stage with a specific shift catalyst upstream, and adjusting temperature and volume ratios to manage reaction heat and prevent nickel carbonyl formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the reaction temperature is kept low to maximize methane production, then the methane content in the gas stream is improved, but the reaction rate becomes slower and the risk of nickel carbonyl formation increases
Solution Approach 1:
The catalyst bed is divided into multiple stages with different temperature zones. The first stage operates at lower temperature (290-350°C) to maximize methane production, while subsequent stages operate at progressively higher temperatures to maintain reaction rate and prevent catalyst deactivation.
Solution Approach 2:
The patent changes the temperature parameter along the length of the catalyst bed, creating a temperature gradient that optimizes both methane production and reaction rate. The temperature increases from the first stage to the last stage, allowing the system to balance thermodynamic equilibrium with kinetic requirements.
2Reliability
If the reaction temperature is kept low to prevent nickel carbonyl formation, then the catalyst reliability is improved, but the reaction rate becomes slower
Solution Approach 1:
The catalyst bed is segmented into multiple stages, with the first stage operating at lower temperature to prevent nickel carbonyl formation and protect catalyst reliability, while subsequent stages operate at higher temperatures to maintain adequate reaction rate.
Solution Approach 2:
The first catalyst stage performs preliminary methanation at controlled lower temperature to convert CO and prevent carbonyl formation before the gas stream proceeds to subsequent stages where higher temperatures can be applied safely.
3Reliability
If a CO conversion stage is added to reduce CO content and prevent carbonyl formation, then the catalyst reliability is improved, but the device complexity and equipment volume increase
Solution Approach 1:
The CO conversion function is merged with the methanation catalyst bed by using the first stage of the methanation catalyst to perform both CO conversion and preliminary methanation, eliminating the need for a separate CO conversion stage and reducing overall equipment volume.
Solution Approach 2:
The methanation catalyst bed is designed to perform multiple functions: CO conversion, methane production, and temperature control. This multi-functionality reduces the need for separate dedicated equipment for each function, simplifying the overall device structure.
4Productivity
If the synthesis gas is heated during CO conversion, then the reaction rate is improved, but the outlet temperature rises and requires additional cooling equipment
Solution Approach 1:
The exothermic heat generated during CO conversion and methanation reactions is converted into a benefit by using it to maintain the temperature of the gas stream, reducing or eliminating the need for external heating and minimizing the temperature increase that would require cooling.
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 lower temperature methanation reactions, reducing reaction heat and increasing methane conversion efficiency, while minimizing catalyst damage and equipment requirements.
Implementation Method 1
a catalyst bed consisting of a methanation catalyst, wherein methanation takes place in the catalyst bed
Implementation Method 2
The formation of methane is accompanied by the generation of considerable heat
Implementation Method 3
the gas stream is heated by released reaction heat
Implementation Method 4
a catalytic shift reaction takes place according to the following reaction equation CO+H2O⇄CO2+H2
Data Source
AI summary
A methane-rich gas from synthesis gas is made in a methane reactor with a row of methanation stages and, at an upstream end of the row of methanation stages, a CO conversion stage. An incoming stream of synthesis gas containing CO and H2 is split into a plurality of partial streams, one of which is fed to the reactor upstream of the CO conversion stage. Each of the other partial syngas streams is fed to the reactor upstream of a respective one of the methanation stages such that methanation takes place in each of the methanation stages and gas exits from the stages and mixes with the partial syngas stream being fed to the next downstream stage. A plurality of partial streams are diverted from a product-gas stream issuing from the furthest downstream stage and are each fed to the reactor upstream of a respective one of the methanation stages.