Biogas Riser Pipe Gas Lift Mixing

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Solution Overview

Problem

Existing biogas plants require mechanical stirring systems for homogeneous mixing of the fermentation medium, which are costly and require intensive maintenance, and do not ensure effective suspension of solids.

Innovation Solution

A biogas plant design where biogas from the first fermentation chamber is introduced into a riser pipe in the second fermentation chamber, utilizing gas pressure to create an ascending flow that circulates the fermentation medium and maintains solids in suspension, potentially aided by a heating device for enhanced mixing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If mechanical stirring systems are used for homogeneous mixing of the fermentation medium, then mixing effectiveness is improved, but acquisition costs and maintenance requirements increase

Engineering Contradiction:
Improvehomogeneous mixing of fermentation mediumVSAvoidmechanical stirring system complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent replaces mechanical stirring systems with a gas-driven circulation system. Biogas produced during fermentation is redirected through a gas line into a riser pipe, creating gas bubbles that rise and drive liquid circulation through density differences, eliminating the need for mechanical agitators while maintaining homogeneous mixing

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention utilizes pneumatic principles by introducing biogas into the riser pipe to create an ascending flow. The gas bubbles reduce the density of the liquid-gas mixture compared to surrounding liquid, generating natural circulation through density-driven flow without mechanical components

Inventive Principle:
Principle #29Pneumatics and hydraulics

2Stability of the object's composition

If mechanical agitators are used to keep solids in suspension, then solids suspension is improved, but maintenance requirements and costs increase

Engineering Contradiction:
Improvesolids suspensionVSAvoidmaintenance requirements
Core Design Contradiction:
Stability of the object's compositionVSEase of repair

Solution Approach 1:

The patent eliminates mechanical agitators by using gas-driven circulation. The biogas introduced into the riser pipe creates upward flow that continuously circulates the fermentation medium, keeping solids in suspension through fluid motion rather than mechanical agitation, thereby reducing maintenance needs

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system uses the biogas produced during fermentation itself as the driving force for circulation. The gas pressure and flow from the fermentation process directly power the mixing and suspension function, making the system self-sufficient without requiring external mechanical energy input or maintenance

Inventive Principle:
Principle #25Self-service

3Device complexity

If gas pressure is used to induce ascending flow in the riser pipe, then mechanical mixing is eliminated, but gas pressure must overcome hydrostatic pressure

Engineering Contradiction:
Improveelimination of mechanical agitatorsVSAvoidgas pressure requirement
Core Design Contradiction:
Device complexityVSStress or pressure

Solution Approach 1:

The patent optimizes the riser pipe geometry and gas injection parameters to achieve effective circulation. By controlling the gas flow rate, riser pipe diameter, and injection point, the system generates sufficient ascending flow using the naturally produced biogas pressure, which typically ranges from 0.5 to 2 meters water column pressure

Inventive Principle:
Principle #35Parameter changes

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 design achieves homogeneous mixing and suspension of solids without mechanical agitators, improving biogas production efficiency and reducing maintenance costs, while ensuring complete decomposition and high-quality biomanure.

Implementation Method 1

The riser pipe of the second fermentation chamber - which preferably extends over at least a large part of the maximum height of the fermentation chamber - is based on the basic principle of a mammoth pump, in which the biogas feed produces a fermentation medium-biogas mixture with a significantly lower specific weight than that of the riser pipe surrounding it

Methodology Applied
Scientific EffectGas lift: Gas Lift

Implementation Method 2

the biogas feed produces a fermentation medium-biogas mixture with a significantly lower specific weight than that of the riser pipe surrounding it. In other words, the rising gas bubbles in the riser pipe of the second fermentation chamber reduce the density of the liquid compared to the surrounding liquid. The difference in density induces an ascending flow in the riser

Methodology Applied
Scientific EffectDensity difference: Density Gradient

Implementation Method 3

the riser pipe has a heating device, preferably a heat exchanger. In this way, the reactor can be heated, with the increased temperature of the liquid in the riser tube generating an additional density difference compared to the liquid in the surrounding reactor space

Methodology Applied
Scientific EffectThermal heating: Heating

Implementation Method 4

the increased temperature of the liquid in the riser tube generating an additional density difference compared to the liquid in the surrounding reactor space

Methodology Applied
Scientific EffectThermal convection: Convection

Data Source

PatentEP2064309B1Biogas system
Publication Date: 2016.05.04 UNIVERSITY OF INNSBRUCK
  • EP2064309B1 patent drawingFigure 1~3

AI summary

The invention relates to a biogas system (1) having a fermenter (2), which has a first and at least a second fermenting chamber (K1, K2) for the fermentation of the fermenting medium, wherein biogas formed in the first fermenting chamber (K1) can be introduced into a riser pipe (7) disposed in the second fermenting chamber (K2).