Designing an inline flare gas combustion chamber

In summary: I 521 states that the flame should stay in the burn chamber by keeping the inlet pipe smaller and the pressure higher. This is done by mixing the correct fuel air mixture to the suction side of the blower where the gas is pulled in.
  • #1
benjaminb
1
0
I have built a nice biomass gasifier that produces about 700,000 btu's of heat per hour by burning or flaring the gas that comes out of it.
What I want to do is, to flare the gas in an enclosed chamber so I would be able to capture all the exhaust and run it through some heat exchangers for heating hot water.
I have a suction fan that pulls the gas out of the gasifier and then blows it into the flare/burn chamber and through the heat exchangers.
In order to save using another blower to blow air, (oxygen) into the flare/burn chamber, I meter it in on the suction side of the blower where it is mixed to the correct fuel air mixture.
This works great burning the gas in the flare/burn chamber into the open atmosphere. But when I put a lid on the chamber and force the exhaust to flow through pipes to the heat exchangers, then the flare doesn't want to stay in the burn chamber. It either jumps down the pipe through the blower right to where the oxygen inlet is, or it travels up the pipes from the burn chamber towards the heat exchangers.
I would like to figure out how to get the flame to stay in the burn chamber.
Does the burn chamber need to be larger?
Does the inlet pipe need to be smaller so the gas is traveling to fast for the flame to jump down the pipe to the oxygen inlet?
What does the pressures and velocities have to do with where the flame stays?
If anyone has any ideas, I'm all ears!
 
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  • #2
benjaminb said:
I have built a nice biomass gasifier that produces about 700,000 btu's of heat per hour by burning or flaring the gas that comes out of it.
What I want to do is, to flare the gas in an enclosed chamber so I would be able to capture all the exhaust and run it through some heat exchangers for heating hot water.
I have a suction fan that pulls the gas out of the gasifier and then blows it into the flare/burn chamber and through the heat exchangers.
In order to save using another blower to blow air, (oxygen) into the flare/burn chamber, I meter it in on the suction side of the blower where it is mixed to the correct fuel air mixture.
This works great burning the gas in the flare/burn chamber into the open atmosphere. But when I put a lid on the chamber and force the exhaust to flow through pipes to the heat exchangers, then the flare doesn't want to stay in the burn chamber. It either jumps down the pipe through the blower right to where the oxygen inlet is, or it travels up the pipes from the burn chamber towards the heat exchangers.
I would like to figure out how to get the flame to stay in the burn chamber.
Does the burn chamber need to be larger?
Does the inlet pipe need to be smaller so the gas is traveling to fast for the flame to jump down the pipe to the oxygen inlet?
What does the pressures and velocities have to do with where the flame stays?
If anyone has any ideas, I'm all ears!

If memory serves me correctly, you should be able to find some information in ANSI/API Standard 521, "Pressure-relieving and Depressurizing Systems".

That standard has a lot of information on flare stacks used in the offshore oil and gas business which sounds similar to what you are working on.

CS
 
  • #3


I would suggest conducting further experiments and simulations to determine the optimal design for your inline flare gas combustion chamber. Here are some potential factors to consider:

1. Chamber size and shape: The size and shape of the chamber can affect the flow of the gas and the stability of the flame. A larger chamber may provide more space for the flame to expand and stabilize, while a smaller chamber may create more turbulence and instability.

2. Inlet pipe size and velocity: As you mentioned, the size and velocity of the inlet pipe can also impact the flow of the gas and the stability of the flame. It is possible that a smaller inlet pipe may result in higher gas velocities, making it more difficult for the flame to jump down the pipe.

3. Pressure differentials: The pressure differential between the gasifier and the flare chamber may also play a role in the stability of the flame. If there is a large difference in pressure, the gas may flow too quickly through the chamber, making it difficult for the flame to stay in place.

4. Heat exchanger design: The design of the heat exchangers may also affect the flow of the gas and the stability of the flame. It is possible that the positioning or size of the heat exchangers may be causing turbulence in the gas flow, disrupting the flame.

5. Computational fluid dynamics (CFD) simulations: Utilizing CFD simulations can help you visualize and analyze the flow of the gas and the behavior of the flame in different designs. This can provide valuable insights and help guide your design choices.

In conclusion, designing an inline flare gas combustion chamber requires careful consideration of various factors such as chamber size and shape, inlet pipe design, pressure differentials, and heat exchanger design. Conducting experiments and simulations can help you determine the optimal design for your specific setup.
 

1. What is the purpose of an inline flare gas combustion chamber?

The purpose of an inline flare gas combustion chamber is to safely and efficiently burn off excess or waste gases from industrial processes. This helps to minimize air pollution and reduce the release of harmful greenhouse gases into the environment.

2. How does an inline flare gas combustion chamber work?

An inline flare gas combustion chamber works by introducing the waste gases into a high-temperature environment and mixing them with a sufficient amount of oxygen. This results in a controlled combustion process that converts the waste gases into carbon dioxide and water vapor, which are less harmful to the environment.

3. What are the key factors to consider when designing an inline flare gas combustion chamber?

When designing an inline flare gas combustion chamber, some key factors to consider include the type and quantity of waste gases, the required combustion temperature, the amount of oxygen needed, and the design of the burner and mixing system to ensure thorough and efficient combustion.

4. How can the efficiency of an inline flare gas combustion chamber be improved?

The efficiency of an inline flare gas combustion chamber can be improved by optimizing the design and placement of the burner, ensuring proper mixing of gases and oxygen, and using advanced technologies such as preheating the gas stream or using a regenerative heat exchanger to recover heat from the combustion process.

5. What safety measures should be taken when designing an inline flare gas combustion chamber?

Safety is a crucial aspect of designing an inline flare gas combustion chamber. Some safety measures that should be considered include proper ventilation and exhaust systems, regular maintenance and monitoring of the chamber, and incorporating emergency shutdown systems in case of any malfunctions. It is also important to comply with relevant safety regulations and standards.

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