Turbo Mash Agitator Control for Biogas Substrate Mixing
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Solution Overview
Problem
Biogas production from agricultural residues like straw and manure faces challenges due to fluctuations in substrate quality and energy content, requiring flexible adjustment of input materials, temperature control, and removal of contaminants, while conventional methods struggle with efficient mixing and oxygen introduction.
Innovation Solution
A turbo mash system with a container having a height-to-diameter ratio of at least 1:3, equipped with a two-stage large-blade propeller agitator and ventilation ring, controlled by a unit that adjusts liquid supply, temperature, and ventilation based on current consumption and gas concentrations to optimize substrate mixing and fermentation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If agricultural residues like straw and manure are used as substrates, then the energy content and flexibility of biogas production are improved, but the substrate quality fluctuates greatly requiring constant adjustment of feedstock amounts
Solution Approach 1:
The system dynamically adjusts operating parameters including liquid supply rate, aeration intensity, and mixing speed based on real-time monitoring of substrate composition and fermentation progress. This dynamic adaptation allows the system to handle varying substrate qualities from agricultural residues while maintaining stable biogas production
Solution Approach 2:
Sensors continuously monitor parameters such as pH, temperature, biogas production rate, and substrate composition. This feedback information is used to automatically adjust feeding rates, liquid addition, and aeration to compensate for substrate quality fluctuations, enabling consistent biogas output despite variable input material
2Use of energy by moving object
If substrates are mixed with liquid in the turbo mash, then oxygen transfer into the liquid is improved, but excess liquid places unnecessary strain on the methane fermenter
Solution Approach 1:
The system optimizes liquid-to-substrate ratio as a controllable parameter, adjusting it based on substrate type and fermentation stage. By precisely controlling the amount of liquid added rather than using excess liquid, the system achieves adequate oxygen transfer for aerobic pretreatment while preventing overloading of the subsequent anaerobic fermenter
Solution Approach 2:
The turbo mash operates with periodic aeration cycles rather than continuous aeration, providing oxygen transfer in controlled intervals. This periodic action maintains sufficient oxygen for aerobic degradation while minimizing total liquid volume requirements and reducing the burden on downstream anaerobic digestion
3Temperature
If the container is heated in winter and cooled in summer for temperature control, then the optimal temperature range for aerobic processes is maintained, but energy consumption increases
Solution Approach 1:
The system utilizes the exothermic heat generated by aerobic biological degradation processes to maintain temperature during colder periods, reducing the need for external heating. The aerobic pretreatment naturally produces heat that can be retained to keep the substrate in the optimal temperature range for mesophilic organisms
Solution Approach 2:
The system recovers and retains heat generated during aerobic pretreatment of the substrate. This recovered thermal energy is used to preheat incoming substrates or maintain fermenter temperature, reducing the overall energy input required for temperature control throughout the year
4Object-affected harmful factors
If stone traps are installed in front of pumps, then contaminants are removed from the process, but the stone traps are barely capable of keeping contaminants away given their type and quantity
Solution Approach 1:
The contaminant removal function is divided into multiple stages: preliminary screening before the turbo mash, mechanical separation during mixing, and final filtration before the fermenter. This segmented approach distributes the filtration load across several points, making each stage more effective than a single stone trap would be
Solution Approach 2:
The liquid medium acts as an intermediary that facilitates contaminant separation. By mixing substrates with liquid in the turbo mash, heavier contaminants like stones and metals settle out or can be mechanically separated more effectively, while the liquid carries the prepared substrate to the fermenter
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 ensures flexible biogas production adapted to energy demands, minimizes liquid usage, prevents floating layers, and enhances oxygen introduction, reducing air requirements and operational costs while maintaining efficient methane production.
Implementation Method 1
an at least two-stage large-blade propeller agitator for mixing in the solid substrates
Implementation Method 2
at least one aeration ring comprising at least one aeration element, which are supplied with air by a compressor
Implementation Method 3
supplied with air by a compressor
Implementation Method 4
aerobic biological processes take place in the turbo mash, which preferably occur in the temperature range between 30 °C and 38 °C and have a positive heat tone, which causes the container to self-heat by several degrees Celsius
Implementation Method 5
to regulate the desired temperature in the turbo mash by heating or cooling
Implementation Method 6
to regulate the desired temperature in the turbo mash by heating or cooling
Data Source
Figure 1
Figure 2
Figure 3a
AI summary
The invention relates to a system for pretreating solid substrates in biogas plants, and a control unit configured to control the quantity of liquid to be supplied by comparing the current current consumption of the agitator with a predetermined current consumption of the agitator, to regulate the temperature in the turbo mash; and to control the quantity of air to be supplied as well as the duration of the aerated and unaerated intervals based on the evaluation of the gas concentrations in the exhaust air, in particular oxygen and carbon dioxide, as well as the fermentation acid profile in the mash liquid. The invention further comprises a biogas plant and a method for producing biogas.