11 replies to this topic

[kangas]

Hi,

 

If you have a batch reactor, where Hydrogen is produced over time. What's the best way to avoid explosive atmospheres by H2 accumulation. Reactor is closed. 

 

N2 is an option. Would you recommend anything else?

[thorium90]

Would dilution with large amounts of air be possible? We commonly do this air dilution in electrochlorination plants.

[Chemitofreak]

Hi,

 

I used to work in a plant where Hydrogenation reaction was carried out, it was batch operation at the end of the cycle we use to remove unreacted hydrogen with the help of a steam ejector and released it to atmosphere at safe location. The steam will dilute the hydrogen concentration below the flammable limit.

 

Regards 

[breizh]

Hi,

Can you describe your process ? How do you operate currently ? Do you monitor the H2 content to ensure you are below the limit of explosivity before opening the manhole ? I'm aware of explosion of reactor with fatality due to wrong operation during the replacement of catalyst .

Breizh 

Edited by breizh, 08 September 2020 - 03:40 AM.

[kangas]

 

Hi,

Can you describe your process ? How do you operate currently ? Do you monitor the H2 content to ensure you are below the limit of explosivity before opening the manhole ? I'm aware of explosion of reactor with fatality due to wrong operation during the replacement of catalyst .

Breizh 

 

Hi Breizh,

 

 

So I am working on the scaleup of a process that currently only lab tests have been done.The first scale up will be a pilot size plant (1.5m3 reactor). We will monitor H2 content as a safety control, but we would like to make sure that no H2 builds up in the reactor (which won't be tight closed, since we need to attach a funnel for solid feeding). H2 is produced as a by-product depending on the different conditions (it's still something that needs to be tested). 

 

Hi,

 

I used to work in a plant where Hydrogenation reaction was carried out, it was batch operation at the end of the cycle we use to remove unreacted hydrogen with the help of a steam ejector and released it to atmosphere at safe location. The steam will dilute the hydrogen concentration below the flammable limit.

 

Regards 

Hi,

 

Were all your moving equipment ATEX?

[Chemitofreak]

Yes, the rotating equipment were ATEX certified

[breizh]

Hi ,

To add to the previous answer, make sure all equipment are ATEX certified  i.e motors but also junction boxes, electrical start/stop, Instrument accessories ,etc 

Pay attention to the zone classification .

 https://www.hse.gov....easareaclas.htm

 

Good luck

Breizh 

[kangas]

Many thanks for your useful information! Much appreciated it!

[PHajiani]

Hi,

 

I used to work in a plant where Hydrogenation reaction was carried out, it was batch operation at the end of the cycle we use to remove unreacted hydrogen with the help of a steam ejector and released it to atmosphere at safe location. The steam will dilute the hydrogen concentration below the flammable limit.

 

Regards 

Hi, Would you please kindly provide a reference for this practice? Or name the process so I can find online references? I need to show that it is a common practice. Thanks. 

[Chemitofreak]

 

Hi,

 

I used to work in a plant where Hydrogenation reaction was carried out, it was batch operation at the end of the cycle we use to remove unreacted hydrogen with the help of a steam ejector and released it to atmosphere at safe location. The steam will dilute the hydrogen concentration below the flammable limit.

 

Regards 

Hi, Would you please kindly provide a reference for this practice? Or name the process so I can find online references? I need to show that it is a common practice. Thanks. 

 

 

The logic behind this operation is to dilute the hydrogen below its LFL (Lower Flammability Limit) so that it will not catch fire. No substance catches fire below LFL and above HFL i.e. the substance is too lean or too rich respectively to catch fire.

 

You can google and find information about the same. As far as steam is concerned, you can replace it with any other inert substance like Nitrogen. The relief should be in atmosphere at safe location.

 

Hope that answers your question. You can google for additional information.

 

Regards   

[Pilesar]

So you have a reaction taking place in an air atmosphere in a small reactor that is not tightly closed and you are concerned that hydrogen may accumulate. Why not just exchange the atmosphere continually with fans? Blowing a continual air stream into the reactor head space seems an easy solution. Is there a good reason you don't like thorium90's suggestion?

[kangas]

So you have a reaction taking place in an air atmosphere in a small reactor that is not tightly closed and you are concerned that hydrogen may accumulate. Why not just exchange the atmosphere continually with fans? Blowing a continual air stream into the reactor head space seems an easy solution. Is there a good reason you don't like thorium90's suggestion?

The reason of not choosing this approach is because I have methanol in the tank and this will drive methanol losses due to evaporation