Biogas Methane CO2 Separation via Amine Chemosorption
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Solution Overview
Problem
Existing methods for separating methane and carbon dioxide from biogas are energetically uneconomical and result in methane gas losses due to high pressure requirements and incomplete CO2 separation, with additional safety and cost burdens in column design.
Innovation Solution
A process utilizing an absorption column operating at normal pressure and temperature with a packing having a large surface area, using an amine solution for chemosorption, followed by desorption under elevated pressure and temperature to achieve complete CO2 separation and efficient methane purification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressure washing is used to separate CO2 from biogas, then CO2 separation is achieved, but energy consumption increases and methane losses occur
Solution Approach 1:
The invention changes the operating parameters from high pressure (10-30 bar) to atmospheric pressure, and from high temperature (40-60°C) to lower temperature (20-40°C). This parameter change eliminates the need for energy-intensive compression while maintaining effective CO2 separation through the use of amine-based washing solutions that work efficiently at these milder conditions.
Solution Approach 2:
The invention replaces the mechanical pressure-based separation system with a chemical absorption system using amine solutions. Instead of relying on high pressure to achieve separation, the system uses the chemical affinity of amines for CO2, substituting mechanical energy input with chemical reaction-based separation that occurs at atmospheric pressure.
2Quantity of substance
If high pressure is applied in absorption columns, then CO2 binding is improved, but methane gas losses increase and safety requirements increase
Solution Approach 1:
The invention changes the pressure parameter from high (10-30 bar) to atmospheric pressure, eliminating methane losses associated with high-pressure operation. The CO2 binding capacity is maintained through the use of amine solutions that have high chemical affinity for CO2, allowing effective separation without requiring pressure elevation.
Solution Approach 2:
The invention substitutes the mechanical pressure-based CO2 binding mechanism with a chemical absorption mechanism using amine solutions. This replacement eliminates the need for high pressure, thereby preventing methane gas losses while maintaining effective CO2 removal through chemical reaction.
3Measurement precision
If pressure washing is used, then CO2 separation is achieved, but additional safety measures and costs are required
Solution Approach 1:
The invention changes the operating pressure from high (10-30 bar) to atmospheric pressure, which eliminates the need for complex high-pressure safety systems. The CO2 separation effectiveness is maintained through the use of amine-based washing solutions that provide efficient chemical absorption at atmospheric pressure, reducing device complexity and safety requirements.
4Measurement precision
If biogas is compressed to high pressure for CO2 removal, then separation is achieved, but energy expenditure increases by 50%
Solution Approach 1:
The invention changes the pressure parameter from high (10-30 bar) to atmospheric pressure, eliminating the energy expenditure associated with gas compression. The CO2 removal efficiency is maintained through the use of amine solutions that provide effective chemical absorption at atmospheric pressure, reducing energy expenditure by approximately 50% compared to pressure washing methods.
Solution Approach 2:
The invention replaces the mechanical compression-based separation system with a chemical absorption system using amine solutions. This substitution eliminates the need for energy-intensive gas compression while maintaining effective CO2 removal, thereby reducing energy expenditure by approximately 50%.
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 achieves complete CO2 separation with minimal methane loss and significantly reduces energy expenditure by 50% compared to pressure washing, allowing for cost-effective and efficient production of high-purity biomethane for natural gas networks.
Implementation Method 1
using an amine solution for chemosorption
Implementation Method 2
followed by desorption under elevated pressure and temperature to achieve complete CO2 separation
Data Source
AI summary
The invention relates to a method of separating methane and carbon dioxide from biogas and to a device for carrying out the method. These are intended for purifying biogas, wherein carbon dioxide is separated off from the biogas. Starting from the disadvantages of the known prior art, a method is intended to be provided which is distinguished by an energetically favourable mode of operation. For this the solution proposed is that the biogas is passed under atmospheric pressure and standard temperature into the absorption column, wherein while the biogas ascends through the packed bed, which preferably has a surface area of 600 to 1200 m2/m3 and at a space velocity of 5 to 40 Nm3/m3h, carbon dioxide present in the biogas is bound in the wash liquid by chemosorption. The purified methane gas is taken off at the top of the absorption column at a defined flow velocity. Carbon dioxide bound in the wash liquid is removed by desorption at a relatively high pressure of 2 to 30 bar and a temperature of at least 120°C. Biogas may be separated particularly economically into methane and CO2 by the suggested procedure.