Digester Desulfurization Net with Hanging Strings
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Solution Overview
Problem
Current in situ air/O2 injection methods for biogas desulfurization are not optimized, leading to the need for additional activated carbon beds to remove hydrogen sulfide, increasing costs and complexity.
Innovation Solution
An installation with a digester and post-digester featuring a desulfurization net and ropes at the biogas-digestate interface, where oxidation gas is introduced to facilitate sulfur attachment and removal by sulfur-oxidizing bacteria, enhancing hydrogen sulfide elimination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If in situ air/O2 injection is used for biogas desulfurization, then hydrogen sulfide elimination is improved, but additional activated carbon beds are required increasing device complexity and cost
Solution Approach 1:
The invention divides the desulfurization function into two parts: (1) in situ oxidation of H2S to elemental sulfur using air/O2 injection, and (2) physical removal of the formed sulfur particles through a filtration system. This segmentation allows the oxidation process to occur within the digester while the filtration handles particle removal, eliminating the need for additional activated carbon beds and reducing overall device complexity.
Solution Approach 2:
The invention introduces an intermediary substance - elemental sulfur formed by oxidation of H2S - that acts as a bridge between the harmful gas phase H2S and the solid phase removal mechanism. The sulfur particles serve as a visible, filterable intermediate that facilitates the transition from gas-phase contamination to solid-phase removal, enabling efficient desulfurization without complex equipment.
2Object-generated harmful factors
If in situ air/O2 injection is used for biogas desulfurization, then hydrogen sulfide elimination is improved, but purification costs increase
Solution Approach 1:
The invention employs inexpensive, easily replaceable filtration elements (such as fabric filters or simple particulate filters) that can be periodically cleaned or replaced at low cost. These disposable or easily maintainable filters replace expensive activated carbon beds, significantly reducing purification costs while maintaining effective sulfur particle removal capability.
Solution Approach 2:
The invention changes the physical state and concentration parameters of sulfur in the biogas stream. By oxidizing H2S to form solid sulfur particles at controlled concentrations, the system transforms a difficult-to-remove gas phase contaminant into easily filterable particulate matter. This parameter change enables the use of simple, low-cost filtration methods instead of expensive chemical absorption processes.
3Object-generated harmful factors
If oxidation gas is injected into biogas overhead, then sulfur formation is improved, but reactivity at the gas-liquid interface is insufficient
Solution Approach 1:
The invention transitions the reaction zone from a three-dimensional gas phase environment to a two-dimensional gas-liquid interface. By concentrating the oxidation reaction at the interface between biogas and digestate, the system creates a high-surface-area reaction zone that dramatically increases the contact area between oxidation gas and H2S, thereby enhancing reactivity and sulfur formation efficiency without requiring excessive oxidation gas injection.
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 effectively reduces hydrogen sulfide levels in biogas to below 200 ppm, reducing purification costs and improving reactivity without complex engineering, by creating additional reaction surface for sulfur products at the gas-liquid interface.
Implementation Method 1
solid sulfur is formed from H2S and O2 (eq. (1)), produced by sulfo-oxidizing bacteria e.g. Thiobacillus
Implementation Method 2
reduction of H2S is also done partly by injecting air/enriched air/O2 into the gas overhead of the digester, which constitutes an in situ solution. With an injection into the gas overhead at a low dose, solid sulfur is formed from H2S and O2 (eq. (1)), produced by sulfo-oxidizing bacteria
Implementation Method 3
the ropes make it possible to offer an additional surface to the sulpho-oxidizing bacteria e.g. Thiobacillus, to eliminate the sulfur at the place where the hydrogen sulphide is the most concentrated
Implementation Method 4
solid sulfur is formed from H2S and O2 (eq. (1))
Data Source
Figure 1
AI summary
Installation for the production of at least partially desulfurized biogas comprising a digester and/or post-digester of biomass, the digester and/or post-digester comprising: - A chamber (1) in which anaerobic digestion of biomass takes place resulting in the production of biogas (2) and digestate (3), - A means for introducing an oxidation gas, - A desulfurization net (4) placed horizontally and fixed in the upper part of the chamber, and - Ropes (5) attached to said desulfurization net and hanging down to the biogas-digestate interface.