Thermophilic Anaerobic Digester with Internal Baffles
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Solution Overview
Problem
Current anaerobic digester systems face challenges such as temperature uniformity issues, accumulation of inorganic and heavy organic matter, and extended hydraulic retention times, leading to reduced efficiency and increased operational costs due to the need for secondary digestion processes.
Innovation Solution
A thermophilic anaerobic digester system with a modular design, optimized vessel geometry, and internal baffles ensures plug flow and uniform heating, allowing for continuous operation with contaminated feedstock, reducing hydraulic retention time, and achieving higher volatile solids destruction and pathogen kill rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If heating coils or pipes are installed under the digester or in central walls to maintain temperature, then temperature control is improved, but heat distribution becomes non-uniform causing hot and cold areas that reduce digester performance
Solution Approach 1:
The digester is divided into multiple heating zones with independently controlled heating elements distributed throughout the vessel. This segmentation allows each zone to be optimized for uniform heat distribution, eliminating the single-point heating problem that causes hot and cold areas.
Solution Approach 2:
Heating elements are positioned in three-dimensional space throughout the digester volume rather than concentrated at the bottom or center. This spatial distribution across multiple dimensions ensures uniform heat penetration and eliminates temperature gradients that reduce performance.
2Device complexity
If the digester operates without agitation to reduce mechanical complexity, then device complexity is reduced, but inorganic and heavy organic materials accumulate reducing operating volume and requiring shutdowns
Solution Approach 1:
The digester design uses the natural convection currents generated by non-uniform heating to create self-agitation. The temperature gradients cause density differences that drive circulating flows, automatically preventing material accumulation without requiring external mechanical agitation devices.
Solution Approach 2:
The system utilizes hydraulic convection currents created by thermal gradients to circulate digester contents. The heated less-dense material rises while cooler denser material sinks, creating continuous natural circulation that prevents accumulation of inorganic and heavy organic materials.
3Ease of manufacture
If the digester uses a shallow lagoon geometry with large surface area to reduce construction cost, then ease of manufacture is improved, but evaporation and lack of agitation cause accumulation of inorganic and heavy organic matter requiring annual shutdowns
Solution Approach 1:
The system transforms the static shallow lagoon into a dynamic system where thermal convection creates continuous circulation patterns. This dynamic flow prevents material accumulation even in shallow geometries, eliminating the need for annual shutdowns while maintaining the cost-effective shallow design.
Solution Approach 2:
The invention changes the thermal parameters of the system by implementing distributed heating that creates strong convection currents. This parameter change transforms the fluid dynamics from stagnant to actively circulating, preventing material accumulation without requiring deeper construction or more complex agitation mechanisms.
4Ease of operation
If the digester operates at mesophilic temperatures to simplify temperature control, then ease of operation is improved, but pathogen kill rates and volatile solids destruction are reduced requiring secondary digestion processes
Solution Approach 1:
The digester is divided into multiple temperature zones, with lower zones operating at mesophilic temperatures for stable operation and upper zones operating at thermophilic temperatures for pathogen kill and enhanced volatile solids destruction. This vertical segmentation allows both temperature regimes to coexist in a single vessel.
Solution Approach 2:
The system uses the vertical dimension to create temperature stratification, with temperature increasing with height in the digester. This dimensional approach allows mesophilic conditions at the bottom for stable digestion and thermophilic conditions at the top for pathogen elimination, eliminating the need for secondary digestion processes.
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
The system achieves faster throughput, higher gas production, superior pathogen and BOD/COD destruction, better odor control, and smaller space requirements, eliminating the need for secondary digestion processes and reducing operational costs.
Implementation Method 1
the heat is transferred by a combination of conduction and convection through the wall and then across the full width of the plug flow within the channel
Implementation Method 2
the heat is transferred by a combination of conduction and convection through the wall and then across the full width of the plug flow within the channel
Implementation Method 3
thermophilic anaerobic digester system
Implementation Method 4
breaks down organic matter into a liquid
Data Source
AI summary
An anaerobic digestion system is provided that includes a blend tank operable to control and perform pre-treatment of feedstock. An anaerobic digester is operable to digest the feedstock provided from the blend tank in a totally enclosed oxygen-free environment within a specific temperature range. A bio-mass tank processes liquid digestate from the anaerobic digester. One or more baffles are positioned in the digester, with the one or more baffles providing for plug flow through at least a portion of the digester to create baffled zones that are at least partially operable independently of adjacent baffled zones. A bio-mass tank processes liquid digestate from the anaerobic digester. An energy source is coupled to the anaerobic digester.