Biogas Digester Concrete Wall Protection Against Sulfuric Acid Corrosion
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Solution Overview
Problem
Fermentation tanks in biogas plants are prone to biogenic sulfuric acid corrosion (BSK), leading to costly damage and downtime due to the production of sulfuric acid from microbiological processes, which attacks the concrete surfaces, especially in the gas exchange zone, causing porosity, cracks, and potential collapse.
Innovation Solution
A protective film is attached to the inner wall of the fermentation tank using anchoring elements, with a media-tight cover at the joints and a crown protector at the top, made of polypropylene with a 1.5 mm thick protective coating, ensuring the film is gas and liquid tight, and anchored using dowels and screws to prevent further damage from BSK.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the fermentation tank is protected with a protective film, then the concrete is protected from further BSK damage and operational life is extended, but the device complexity increases due to additional components (protective film, anchoring elements, covers, seals)
Solution Approach 1:
The protective system is segmented into distinct functional components: the protective film itself, anchoring elements for attachment, covers for sealing anchor points, and crown guards for edge protection. This segmentation allows each component to be optimized independently and facilitates easier installation and maintenance of the overall protection system.
Solution Approach 2:
The solution employs composite material structures, combining the protective film with anchoring elements made of corrosion-resistant materials, sealed with media-tight covers. This composite approach creates a multi-layered defense system that leverages the strengths of different materials to provide comprehensive protection against BSK while managing the complexity through functional integration.
2Reliability
If a protective film is applied to the entire wall, then complete protection from BSK is achieved, but the cost and time for application increases significantly
Solution Approach 1:
The protective film is strategically applied only to the gas exchange zone where BSK occurs most severely, rather than covering the entire wall. This localized approach maintains high reliability in the most vulnerable areas while significantly reducing material costs and application time. The crown guards and anchoring elements are also positioned specifically at critical locations to maximize protection efficiency.
3Strength
If the protective film is anchored to the wall, then the film remains securely in place, but the anchoring elements create potential entry points for corrosive media
Solution Approach 1:
Media-tight covers are introduced as intermediary elements that seal the anchoring points where the protective film attaches to the wall. These covers act as mediators that maintain the mechanical attachment function while simultaneously blocking the penetration pathway for corrosive media, thus resolving the contradiction between secure anchoring and corrosion prevention.
Solution Approach 2:
The anchoring elements and their protective covers are designed to prevent corrosion before it can occur at the vulnerable anchor points. By pre-sealing these potential entry points with media-tight covers, the system proactively counteracts the harmful effect of corrosive media attempting to penetrate through the anchoring locations.
Data Source
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AI summary
The invention relates to a method for protecting a digester (5) of a biogas plant by means of the following steps: At least one circumferentially circumferential strip of a protective film (10) is arranged on the inside of the wall (9) of the digester (5), which is attached to the wall (9) by means of several anchoring elements (14). A cover (22) is welded onto the protective film (10) in a media-tight manner in the area of the anchoring elements (14) and in the area of the joint (12) between the beginning and end of the protective film (10).The invention also relates to a digester (5) for a biogas plant, comprising a concrete wall (9) which is pre-damaged by aggressive media at least in one gas exchange zone, and a protective film (10) which is attached to the wall (9) inside the digester (5), wherein the protective film (10) is provided at its upper edge with a crown guard (30) which extends outwards over the upper edge of the wall (9), wherein a seal (16) is provided between the lower edge of the protective film (10) and the wall (9), and wherein several anchoring elements (14) are provided with which the protective film (10) is anchored to the wall (9) of the digester (5), wherein the anchoring elements (14) are covered in a media-tight manner by a cover (22) which is welded to the protective film (10).