Anaerobic Fermentation Tank with Return Opening for Biogas

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Solution Overview

Problem

Anaerobic fermentation processes face challenges such as incomplete fermentation, rapid pass-through of fresh organic material, and reduced biogas production, leading to energy loss and potential survival of germs in the digestate.

Innovation Solution

A method involving the mixing of organic material with an inoculant and the use of a return opening to recycle partly fermented material as an active inoculant, allowing for internal after-fermentation within the same reactor, creating separate zones for extended lingering periods and optimizing biogas production.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If fresh organic material is rapidly mixed and fermented in wet systems, then mixing efficiency is improved, but pass-through time becomes too short causing incomplete fermentation

Engineering Contradiction:

Improvemixing efficiencyVSAvoidpass-through time

Core Design Contradiction:

Ease of operationVSDuration of action of moving object

Solution Approach 1:

The fermentation tank is divided into two distinct zones: a first zone for intensive mixing and initial fermentation, and a second zone for extended retention and completion of fermentation. This segmentation allows the system to achieve both efficient mixing and adequate pass-through time by separating these functions spatially.

Inventive Principle:

Principle #1Segmentation

2Duration of action of moving object

If dry fermentation is used to extend retention time, then fermentation completeness is improved, but mixing efficiency deteriorates due to high viscosity

Engineering Contradiction:

Improveretention timeVSAvoidmixing efficiency

Core Design Contradiction:

Duration of action of moving objectVSEase of operation

Solution Approach 1:

Different zones within the fermentation tank are assigned different operational characteristics: the first zone operates with conditions favorable for mixing (lower viscosity, higher water content), while the second zone provides extended retention (higher dry matter content, slower flow). This local differentiation allows each zone to optimize its specific function.

Inventive Principle:

Principle #3Local quality

3Duration of action of moving object

If additional fermentation tanks are added to extend retention time, then fermentation completeness is improved, but device complexity increases

Engineering Contradiction:

Improvefermentation timeVSAvoidnumber of fermentation tanks

Core Design Contradiction:

Duration of action of moving objectVSDevice complexity

Solution Approach 1:

Multiple fermentation stages (intensive mixing phase and extended retention phase) are merged into a single fermentation tank by creating distinct zones within it. This eliminates the need for multiple separate tanks while achieving the same functional outcome of extended and complete fermentation.

Inventive Principle:

Principle #5Merging (Combining)

4Productivity

If fresh material is quickly processed through the system, then productivity is improved, but biogas production is reduced due to incomplete fermentation

Engineering Contradiction:

Improveprocessing speedVSAvoidbiogas production

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The fermentation process is segmented into two zones: the first zone enables rapid processing of fresh material through intensive mixing, while the second zone ensures complete fermentation for maximum biogas production. This segmentation allows the system to maintain high productivity while avoiding energy loss from incomplete fermentation.

Inventive Principle:

Principle #1Segmentation

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 extends the pass-through time of fresh organic material, maximizes biogas production, and ensures effective germ killing, eliminating the need for additional fermentation tanks while maintaining biological stability and adjusting pH levels.

Implementation Method 1

In a first zone (A) of the fermentation tank (1), organically inoculated material is supplied and anaerobically fermented

Methodology Applied

Scientific EffectAnaerobic fermentation: Anaerobic Digestion

Implementation Method 2

anaerobically fermented

Methodology Applied

Scientific EffectBiological decomposition: Decomposition (biological)

Implementation Method 3

a fraction of the fermenting material, situated between the inlet and the outlet, is prematurely removed from the fermentation tank via a return opening and is carried up to the feed device

Methodology Applied

Scientific EffectMaterial recycling:

Implementation Method 4

organic material to be fermented which is mixed with inoculant and supplied into a fermentation tank and which moves on from an inlet of the fermentation tank to an outlet

Methodology Applied

Scientific EffectGravitational flow: Gravitation

Data Source

PatentEP1930404B1Method and device for the anaerobic fermentation of organic material

Publication Date: 2012.03.28 ORGANIC WASTE SYSTEMS NV

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AI summary

Method for the anaerobic fermentation of organic material, whereby the organic material to be fermented is put in a fermentation tank (1) together with an inoculant and moves or is moved from an inlet (6) of the fermentation tank (1) to an outlet (9) thereof, whereby the fermented material is removed from the tank (1) via the outlet (9), characterized in that a fraction of the fermenting material which is situated between the inlet (6) and the outlet (9) is removed from the fermentation tank (1) via a return opening (12) and is used as an inoculant, while the fermenting material between the return opening (12) and the outlet (9) is still after-fermented for a certain while before it is removed from the fermentation tank (1) via the outlet (9).