Biogas Buffer Storage System for Digester Pressure Control
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Solution Overview
Problem
Biogas facilities face pressure and flow rate fluctuations in anaerobic digesters, leading to system damage, unnecessary flare operations, and revenue loss due to inconsistent biogas flow, which affects the efficiency and operation of renewable natural gas facilities.
Innovation Solution
A biogas buffer storage system with a control system that uses a pressure transmitter and variable frequency drive-enabled screw compressor to modulate digester pressure and flow rate, capturing excess biogas and maintaining consistent flow by storing it in a buffer vessel for later use during low flow periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a flare is used to handle excess biogas pressure, then pressure relief is achieved, but biogas is wasted and revenue is lost
Solution Approach 1:
A buffer storage vessel is introduced as an intermediary component between the digester and the flare system. This vessel temporarily stores excess biogas that would otherwise be burned off, allowing the system to maintain pressure relief while preserving the biogas for later use during low-flow periods
Solution Approach 2:
The buffer storage vessel performs preliminary storage of excess biogas before it reaches the flare system. By capturing and holding the biogas in advance, the system prevents immediate waste while maintaining operational pressure control in the digester
2Stability of the object's composition
If biogas flow is not continuous from the digester, then pressure control is difficult, but the system becomes more complex to manage
Solution Approach 1:
The buffer storage vessel serves as a mediator that decouples the variable output of the digester from the requirements of the downstream processing equipment. This intermediary storage allows the system to handle inconsistent biogas flow without requiring complex active control mechanisms
Solution Approach 2:
The buffer storage vessel provides beforehand cushioning by maintaining a reservoir of biogas that can compensate for fluctuations in digester output. This cushioning effect smooths out flow variations and maintains stable operation without complex control systems
3Reliability
If the digester pressure gets too high, then system damage may occur, but flaring causes shutdown and revenue loss
Solution Approach 1:
The buffer storage vessel acts as an intermediary pressure management device that prevents excessive digester pressure by providing an alternative storage path for excess biogas. This eliminates the need to flare and subsequently shutdown the facility, maintaining both safety and productivity
Solution Approach 2:
The system converts what would be a harmful excess pressure condition into a beneficial stored resource. By directing excess biogas to the buffer storage vessel instead of flaring, the system transforms a potential safety hazard into a valuable fuel reserve that can be used during low-flow periods
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 solution stabilizes biogas flow, reduces waste, optimizes output, and enhances the efficiency of the renewable natural gas facility by maintaining normal operating conditions and preventing unnecessary shutdowns, thereby increasing the quality and consistency of the biogas output.
Implementation Method 1
the buffer storage system controller will start a buffer screw compressor or similar compressor
Implementation Method 2
The biogas compressed by the buffer screw compressor may be stored in a buffer storage vessel
Data Source
AI summary
Processes, systems, and associated control methodologies are disclosed that control the flow of biogas during the biogas cleanup process to create a more consistent flow of biogas through the digester, while also optimizing the output and efficiency of the overall renewable natural gas facility. In representative embodiments, a biogas buffer storage system may be used during the cleanup process to control the pressure and flow rate of biogas. The biogas buffer storage system may monitor and control the biogas flow rate to either bring down or increase the digester pressure, thereby maintaining a normalized biogas flow rate.