Bioreactor Mist for Explosion Prevention

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Solution Overview

Problem

Bioreactors face a risk of explosion due to the presence of flammable gases and oxygen in the gaseous sky, which can lead to significant safety and economic challenges in biogas production.

Innovation Solution

A misting device generates a non-flammable liquid mist with droplets less than 1 mm in diameter, capable of absorbing heat radiation, trapping oxygen, and reducing the oxygen content, thereby reducing or eliminating the risk of explosion by maintaining high humidity and preventing energy transfer during potential ignition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the bioreactor is designed to withstand thermal explosion, then safety is improved, but economic profitability deteriorates due to considerable costs

Engineering Contradiction:
ImprovesafetyVSAvoideconomic profitability
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The system performs preliminary action by injecting a non-flammable gas (nitrogen or carbon dioxide) into the bioreactor before the explosive conditions can develop. This proactive measure prevents the formation of an explosive atmosphere by displacing oxygen, thereby avoiding the need for expensive explosion-resistant reactor designs while maintaining safety

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

A non-flammable gas acts as an intermediary substance between the flammable biogas and the oxygen in the air. This intermediary gas creates a physical barrier that prevents the ignition and propagation of explosions, protecting the bioreactor without requiring it to be built with expensive explosion-resistant materials

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the bioreactor is designed to withstand thermal explosion, then safety is improved, but device complexity increases

Engineering Contradiction:
ImprovesafetyVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system performs preliminary action by injecting a non-flammable gas (nitrogen or carbon dioxide) into the bioreactor before the explosive conditions can develop. This proactive measure prevents the formation of an explosive atmosphere by displacing oxygen, thereby avoiding the need for expensive explosion-resistant reactor designs while maintaining safety

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

A non-flammable gas acts as an intermediary substance between the flammable biogas and the oxygen in the air. This intermediary gas creates a physical barrier that prevents the ignition and propagation of explosions, protecting the bioreactor without requiring it to be built with expensive explosion-resistant materials

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If liquid mist is generated to reduce explosion risk, then safety is improved, but liquid consumption increases

Engineering Contradiction:
ImprovesafetyVSAvoidliquid consumption
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The system changes the parameter of droplet size by using ultrasonic vibration to generate extremely fine mist with droplet diameters of 1 micrometer or less. This parameter change dramatically increases the surface area to volume ratio, allowing much lower liquid consumption (0.01-10 mL/m³) while maintaining effective explosion prevention through enhanced heat absorption and oxygen displacement

Inventive Principle:
Principle #35Parameter changes

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 liquid mist effectively reduces the risk of explosion by absorbing thermal radiation, maintaining high humidity, and lowering oxygen levels, allowing for safe biogas production with minimal liquid consumption, even in aerobic fermentations, thus enhancing operational safety and economic viability.

Implementation Method 1

The absorption of thermal radiation by the liquid mist reduces the risk of ignition of the gaseous sky by heating

Methodology Applied
Scientific EffectAbsorption of thermal radiation: Absorption (EM radiation)

Implementation Method 2

The liquid mist allows cooling of the internal walls of the bioreactor in its upper part. This reduces the risk of mechanical bursting due to gas compression

Methodology Applied
Scientific EffectCooling: Cooling

Implementation Method 3

The liquid mist makes it possible to lower the oxygen content of the gaseous sky by dissolving in droplets of this liquid at least a part of the residual oxygen contained in the gas leaving the reaction medium

Methodology Applied
Scientific EffectDissolution: Solvation

Data Source

PatentEP3406702B1System and method for producing biogas
Publication Date: 2020.04.08 IPSB
  • EP3406702B1 patent drawingFigure 1

AI summary

Biogas is produced using a bioreactor (5) comprising a reaction medium and a gaseous headspace (4) above the reaction medium. A misting device (2, 3, 9) generates a mist of non-flammable liquid in the gaseous headspace (4) of the bioreactor (5) by misting. The non-flammable liquid mist comprises droplets with a nominal diameter of less than 1 mm, so that the non-flammable liquid mist is capable of absorbing thermal radiation and trapping oxygen. This reduces, or even eliminates, the risk of explosion in the bioreactor (5).