For magnet wire annealers, the really large wire sizes are usually coated on a vertical oven. The annealers are often also vertical. the wire enters at the top and travels downward to the floor. the outlet of the annealer tubes are usually submerged in water. The temperature of the water is controlled so that it maintains a temperature that allows the water on the wire to evaporate from the wire surface before it reaches the applicator. The hot wire in the annealer tube creates steam when the hot wire contacts the water. The steam rises creating an atmosphere in the tube that prevents oxidation. Some of the annealers also inject inert gases into the tube but generally not needed.
For horizontal annealers (note some annealers are electrically heated and some by natural gas, propane or manufactured gases) Often there is a steam generator that injects steam into the tube a couple of feet from the exit. slotted plugs are usually used to reduce the cross section of the opening and exit of the tube. Steam is regulated to each tube so that there is a wisp of steam coming from the tube. you have to be careful that the steam is not condensing in the tube. For really fine wire the increased drag from the presence of the condensate can cause the wire to stretch.
The larger wire horizontal annealers can have steam or an inert gas depending upon it is electric or gas heated.
For really fine wire, nitrogen is a very good alternative for a couple of reasons. it does not condense so there is no increased drag on the wire. The tubes are quite small so you are not using large quantities of nitrogen. It is easy to regulate. It is essentially maintenance free and the tubes don't clog from calcification sediment from the water or steam. When ever possible if using steam, used deionized water.