Residual Gas Combustion Control for Biogas Purification

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Solution Overview

Problem

Current methods for treating residual gases from biogas purification, such as methane oxidation, trapping, and combustion, either fail to recover methane efficiently or incur high costs, and struggle with incomplete combustion when the methane content is low, leading to inefficient energy recovery and excess methane release into the atmosphere.

Innovation Solution

A system and process that calculates and supplies the precise amount of oxygen needed for complete combustion of residual gases, using a control module to determine the methane volume fraction and enrich atmospheric air with dioxygen based on specific factors, ensuring efficient combustion without additional methane injection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If high purification efficiency is used to maximize biomethane production, then methane content in residual gases is reduced, but investment and operating costs of the purification unit increase

Engineering Contradiction:
Improvebiomethane productionVSAvoidpurification unit cost
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The invention changes the operating parameters of the combustion module by adjusting the air-to-fuel ratio and combustion temperature to optimize the combustion of residual gases with varying methane concentrations, allowing efficient energy recovery across different purification efficiency levels without requiring always-maximal purification capacity

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention converts the previously harmful residual gases (containing methane that would be released to atmosphere) into a beneficial energy source by combusting them in a dedicated combustion module, transforming waste into useful thermal energy for water heating or process applications

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

2Object-affected harmful factors

If methane oxidation processes are used to meet discharge thresholds, then methane content in released gases is reduced, but methane energy recovery is lost

Engineering Contradiction:
Improvemethane emissionVSAvoidmethane energy
Core Design Contradiction:
Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

Instead of simply oxidizing methane to meet emission standards (which destroys the energy), the invention captures the residual gases and combusts them in a controlled manner to recover energy as heat, while still reducing methane emissions by converting the methane into CO2 and H2O through complete combustion

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Loss of energy

If residual gas combustion is performed with low methane content, then energy recovery is reduced, but complete combustion becomes difficult to achieve

Engineering Contradiction:
Improveenergy recoveryVSAvoidcombustion completeness
Core Design Contradiction:
Loss of energyVSReliability

Solution Approach 1:

The invention adjusts combustion parameters including air-to-fuel ratio, combustion chamber temperature, and residence time to ensure complete combustion even when methane content in residual gases is low, maintaining reliable and complete combustion across varying gas compositions

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The system monitors combustion conditions and residual gas composition to dynamically adjust operating parameters, ensuring complete combustion is maintained even when methane content varies, preventing incomplete combustion and ensuring reliable energy recovery

Inventive Principle:
Principle #23Feedback

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 complete combustion of residual gases, minimizing methane release into the atmosphere and optimizing energy recovery, while reducing operational costs by avoiding the need for pure oxygen and minimizing methane from the fermenter.

Implementation Method 1

combustion of the methane contained in the residual gases

Methodology Applied
Scientific EffectCombustion: Combustion

Implementation Method 2

combustion of the methane contained in the residual gases

Methodology Applied
Scientific EffectOxidation: Oxidation

Data Source

PatentEP3862411B1Treatment of residual gas from purification of biogas
Publication Date: 2022.03.09 PRODEVAL SAS
  • EP3862411B1 patent drawingFigure 1
  • EP3862411B1 patent drawingFigure 2
  • EP3862411B1 patent drawingFigure 3

AI summary

biomethane production system (1) comprising a biogas production module (10) (F0), a purification unit (20), a residual gas combustion module (30), a supply module (40) and a control module (50) capable of determining the volume fraction of methane (Y CH4 residual) of the residual gas stream (F2), of calculating an oxygen enrichment rate (Y O2 enriched air), at least one supply module (40) being capable of generating a gas stream whose proportion of oxygen is equal to the oxygen enrichment rate (Y O2 enriched air) and of supplying the generated stream (F4) to the combustion module (30).