Steam activation is the opening and development of the porosity of a carbon material through its mild oxidation caused by hot steam passing on it. At 700 - 800°C, typically, H2O reacts with carbon and produces CO + H2. Therefore, the carbon is consumed and very narrow pores are produced (which progressively widen with time), and you get activated carbon.

It is quite easy to do it. Just bend slightly your furnace by a few degrees, and introduce water drom by drop in the flow of nitrogen at a temperature of, say, 750°C. A pump can be used for that, so that the flow of water is controlled but very very low (drop by drop). Each drop will roll towards the hot part of the furnace and transform into steam, which will react with the carbon.

You need to control the time. 15 min can be enough for getting a good burn-of (25%) and 30 min can burn everything. Sometimes, not , as it depends on temperature and carbon. Nothing else but doing trials.

Alain

Dear Celzard,

Thank you very much for your time and valuble information. It is informative. I will try to implement that with my work. Thank you once again 

A very complete and informative answer. Nothing to add to Alain contribution.

Agreed with Juan Casado.

Alain's answer was great.

I just want to add that for enter water into the gas stream, the best and more controllable way is to use a bubble saturator (see link below), it is cheap and you can can control the saturation by putting the bubbler in a temperature controlled bath.

https://www.osha.gov/dts/osta/otm/otm_ii/otm_ii_1photo02.gif