Structured-Packing Methanation Reactor for CO2 and pH Control
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Solution Overview
Problem
Existing methanization reactors face challenges in achieving high conversion rates of hydrogen and carbon dioxide to methane due to pH fluctuations caused by carbon dioxide solubility, leading to acidification and reduced efficiency, especially when hydrogen is in surplus.
Innovation Solution
A device and method that regulate the amount of dissolved carbon dioxide in the liquid nutrient medium by controlling the liquid level in the methanization reactor, using structured packings and aeration lances to introduce carbon dioxide and hydrogen, maintaining a stoichiometric excess of hydrogen and controlling pH through adjustable immersion depth of aeration lances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If carbon dioxide is continuously supplied in excess to achieve high conversion rates, then methane production increases, but the liquid medium becomes acidified due to dissolved CO2 forming carbonic acid
Solution Approach 1:
The patent implements dynamic control of the liquid level in the reactor to regulate the immersion depth of aeration lances. This dynamic adjustment allows the system to optimize CO2 dissolution and methane production while preventing excessive acidification by controlling the amount of CO2 that dissolves into the liquid medium, thus adapting to varying operational conditions.
Solution Approach 2:
The patent changes the physical parameter of liquid level height to control the process. By adjusting the liquid level, the immersion depth of aeration lances is modified, which directly affects the amount of CO2 dissolving into the medium. This parameter change enables precise control over the balance between methane production and pH stabilization.
2Productivity
If hydrogen is supplied in stoichiometric excess to maximize conversion rates, then methane yield increases, but excess hydrogen must be separated for gas grid injection
Solution Approach 1:
The patent utilizes the natural solubility differences and reaction kinetics to allow the methanogenic microorganisms to self-regulate the consumption of hydrogen and CO2. By controlling the liquid level and aeration, the system enables the biological process itself to manage the stoichiometric balance, reducing the need for external separation mechanisms while maintaining high conversion rates.
3Productivity
If the liquid level is increased to enhance CO2 dissolution and methane production, then conversion rates improve, but pH control becomes more difficult due to increased carbonic acid formation
Solution Approach 1:
The patent employs dynamic liquid level control to adjust the immersion depth of aeration lances in real-time. This dynamic approach allows the system to optimize CO2 dissolution for high conversion rates while simultaneously preventing excessive pH acidification by regulating the amount of CO2 that contacts and dissolves in the liquid medium.
Solution Approach 2:
The system implements feedback control through liquid level regulation, where the liquid level itself serves as the control variable. By monitoring and adjusting the liquid level, the system provides feedback control over the dissolution process, ensuring that CO2 is dissolved at optimal rates for methane production without causing harmful acidification.
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 enables consistently high conversion rates, producing 100 m³ of methane per hour from 100 m³ of reactant gas, with pH stabilization and efficient hydrogen utilization, ensuring high methane yields and productivity.
Implementation Method 1
Biological methanization is based on the activity of methanogenic microorganisms (archaea) that convert carbon dioxide (CO2) and hydrogen (H2) into methane (CH4) and water (H2O)
Implementation Method 2
carbon dioxide is more soluble in liquids than hydrogen, leading to the formation of carbonic acid (H2CO3) even at low partial pressures. This lowers the pH of the liquid
Data Source
Figure 1
Figure 2A~2B
AI summary
The present invention relates to an apparatus and method for increasing the conversion rates in biological methanization for the production of methane from hydrogen and CO2-containing gas. The apparatus comprises a column (10) with structured packings (12) arranged inside the column body for mass transfer between different phases, an outlet for produced methane-containing product gas (14) and an inlet for liquid nutrient medium (16) in the top region of the column, and an outlet for the liquid nutrient medium (26) and an inlet for hydrogen (24) in the bottom region of the column. A liquid chamber (20) for the liquid nutrient medium is provided below the structured packings (12), the liquid level (32) of which in the liquid chamber (20) can be variably controlled via the filling volume during operation.In the upper part of the liquid chamber (20), at least one ventilation lance (22) extending obliquely downwards into the liquid chamber (20) is provided, through which CO2 gas can be introduced into the liquid chamber (20) of the column (10), while hydrogen is introduced into the liquid chamber (20) via the hydrogen inlet (24) located below it. With this device and method, it is possible to regulate the amount of CO2 introduced into the liquid and its pH value by changing the liquid level in the liquid chamber.