Biogas Facility Venting Design to Prevent Hydrogen-Oxygen Explosion
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Solution Overview
Problem
Existing biogas production facilities face the risk of explosion due to the accumulation of hydrogen and oxygen, which are non-condensable gases that permeate through membranes and accumulate during the biogas purification process, leading to hazardous concentrations.
Innovation Solution
A biogas production facility equipped with a biogas membrane separation unit, cryogenic distillation unit, and membrane stages to separate methane from an oxygen-hydrogen mixture, with a vent for evacuating the hazardous gases, ensuring continuous recycling of methane and safe evacuation of the oxygen-hydrogen mixture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If hydrogen and oxygen are recycled indefinitely between the purifier and liquefier, then resource utilization is improved, but explosion risk increases due to accumulation of hazardous gases
Solution Approach 1:
The patent extracts the hazardous oxygen-hydrogen mixture from the recycling loop by introducing a vent stream that removes a portion of the recycled gas before it re-enters the purifier. This prevents the accumulation of explosive gases while maintaining the beneficial recycling of methane and other non-hazardous components.
Solution Approach 2:
The patent changes the composition parameter of the recycled gas by selectively removing oxygen and hydrogen through the vent stream. This alters the explosive characteristics of the recycled gas while preserving its utility for further processing.
2Manufacturing precision
If membranes are used to separate gases, then purification efficiency is improved, but hydrogen and oxygen accumulate in the vent stream creating safety hazards
Solution Approach 1:
The patent converts the harmful accumulation of oxygen and hydrogen in the vent stream into a beneficial controlled removal mechanism. By intentionally venting a portion of the recycled gas, the system safely eliminates hazardous gases while maintaining high purification efficiency through the membrane separation process.
3Productivity
If the vent stream is directed to the CO2 liquefaction unit, then CO2 recovery is improved, but hydrogen concentration increases posing explosion risks
Solution Approach 1:
The patent extracts hydrogen from the system by directing the vent stream to the CO2 liquefaction unit where non-condensable gases including hydrogen are removed. This prevents hydrogen accumulation while maintaining efficient CO2 recovery and liquefaction.
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 solution effectively prevents explosion risks by safely venting out hazardous gases while increasing methane yield and ensuring the safety of the facility operation.
Implementation Method 1
hydrogen is a very small molecule which permeates through the membranes and therefore ends up in the vents of the purification unit
Implementation Method 2
A cryogenic distillation unit for the gas mixture M1 for producing liquid CO2 and a gas mixture M2 comprising carbon dioxide, methane, oxygen and hydrogen
Data Source
Figure 1
AI summary
The invention relates to a facility for producing liquid CO2 and biomethane, comprising :- a unit for producing biogas;- at least one unit for the membrane separation of biogas to produce biomethane and a gaseous mixture M1 mainly comprising carbon dioxide;- a unit for cryogenically distilling the gaseous mixture M1 to produce liquid CO2 and a gaseous mixture M2 comprising carbon dioxide, methane, oxygen and hydrogen; - one or more membranes located in the flow of the gaseous mixture M2 to separate the methane from the oxygen-hydrogen mixture contained in the gaseous mixture M2; - a means for recirculating the methane originating from the gaseous mixture M2 to the membrane separation unit; and - a vent for removing the oxygen-hydrogen mixture originating from the gaseous mixture M2.