Reformimg of pyrolysis gas with steam and air

[Ujjwal Thakur]

Hello Everyone!
I have a question related to reforming process.

In a process to pre-reform pyrolysis gas (from plastic waste) with steam to obtain hydrogen rich synthesis gas (CO+H2). I am entering high temperature (500°C) pyrolysis gas( 3.5% methane and 7-8% other short chain geseous hydrocarbons+CO+H2+N2+CO2+CO) with steam and also adding air in the pipeline and then sending to reactor (spouted bed) with dolomite catalyst. The air and pyrolysis gas flow is same , will some high combustion take place before? Is there any problem to add air in the mixture of steam and gas? Will the complete gas react with air before getting reformed?

Any suggestions?

 

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[georgeverghese]

You can use air, but it is better to use pure O2 (if you must to get the required CO:H2 ratio), as this will minimise the additional diluent N2 effect on the steam reforming and the shift gas reactions.

 

[Ujjwal Thakur]

Thank you very much for your response. I would like to know adding a premix fuel ( pyrolysis gas + air) seems little dangerous, what do you suggest?

 

[georgeverghese]

There will be partial oxidation of the pygas, but not combustion. Keep pipe velocity low, have the pipes well grounded to prevent electrical sparks, and keep O2 concentration to allow partial oxidation only.
I would prefer not to add air or O2, and use steam based reforming only, but maybe you have a certain CO:H2 ratio to achieve that does not allow this.

 

[Ujjwal Thakur]

Thank you very much for the kind response. I would take care of that. Yeah we are providing air at the reactor to provide autothermal heat for the steam reforming reactions. Yeah you are right for the certain H2/CO ratio as well.
Thank you