thermal oxidizer / fired heater

[Julian88]

Hi,

I have been given a design project where i have to design a thermal oxidizer to get rid of a stream of gas that consist of 86% nitrogen, 0.3% Methane and the rest CO2, H2 and H2O.
Should i use a thermal oxidizer or fired heater? which is easier? as im expected to do calculations on them etc.
Have not got a clue on where and how to start the task. Hope you could advice on this.

Thanks alot for your time.

Regards,

Julian.

 

[owg]

I would ask for clarification on what "get rid of" means.

HAZOP at

http://www.curryhydrocarbons.ca

 

[Julian88]

i assume the major concern of discharging this stream is into the environment is the methane gas? and any NOx that is formed from the combustion? is there any book that would be of help in designing this? should it be a fired heater or thermal oxidizer?

 

[Latexman]

Are you sure it has to be treated? Ask your local environmental authority. If it does have to be treated, they can probably help you get started.

The way I handle equipment that I am not familiar with is write up a performance specification and offer it for bid to some reputable companies. These companies can probably give you forms for the information they need.

Good luck,
Latexman

 

[Julian88]

i'm actually tasked with designing it, having only a bit of chemical eng background. its starting at point zero for me. are u familiar with a thermal oxidizer or fired heater?

 

[sshep]

Thermal oxidizer is a pretty generic term. The simplest thermal oxidizer is in fact just a fired heater which serves no other purpose than to burn waste gas, however, this costs fuel- i.e. the easiest and cheapest to build, but most expensive to operate. RTO's make use of heat recovery so they cost more to build, but less to operate.

If you have a fired heater doing something else (boiler, hot oil, process heater, etc) and the stream is small enouh, then putting a disposal burner in that is your absolute cheapest option. Otherwise these things are a matter of economics and there is no single answer.

What is the mass of the stream?

 

[Julian88]

9199.9kg/hr

 

[Latexman]

Then I suggest you look at a catalytic oxidizer. That's pretty big compared to what I'm used to.

Good luck,
Latexman

 

[frguic]

Hi everyone,

I am working on an thermal oxidizer and i am wondering if it can be assimilate to a fired heater ? I am asking that for knowing if API 560 will apply in my case.

 

[786392]

Dear Hello/Good Afternoon,

Kindly start new thread!
Thanks.

Best Regards
Qalander(Chem)

 

[KiwiMace]

Start with a vendor, they will tell you what they think you need and what that costs. Even if you are going to build your own solution, you need an idea of what the market price is just to set a budget.

 

[TD2K]

I'd suggest talking to John Zink, they make thermal oxidizers.

You've got a lot of nitrogen which likely means an external fuel stream to support combustion (I doubt there's enough H2 to maintain combustion). If you have an existing fired heater you can dispose of waste gases in them but to dispose of this stream if an existing heater isn't available you really want an incinerator of some sort.

I suppose the methane prevents you from just venting it to the atmosphere?

 

[Julian88]

My stream is 0.43% methane,65% N2,26% Hydrogen,0.65% carbon dioxide, 7.2% carbon monoxide. . the lower flambility limit for hydrogen is 5% . does this means if i just give a spark to this stream.its gonna lit?

 

[danw2]

Where's the oxygen going to come from to burn any of the gases?

 

[Julian88]

silly me.. ya, im added some natural gas and oxygen to come to a 6% methane gas and 5% hydrogen concentration. think both of it would ignite ?

 

[TD2K]

26% H2 gives you a heating value for the mixture of about 85 BTU/scf (the 0.4% methane doesn't add much) which is pretty low but H2 is pretty easy to burn.

For example, the EPA flags gases with less than 300 BTU/scf as being difficult to burn in a flare. 100% H2 is 325 BTU/scf but you would have no problem burning it in a flare .

I'd talk to John Zink or another TO vendor, I'm not sure what the answer is.