When they are doing well, some orchids secrete droplets of sap. sometimes called 'happy sap'. It's sweet so attracts insects. I'd be surprised if the ants are doing anything beyond harvesting this liquid and taking it back to their nest so, in my inexperienced opinion, they are unlikely to do any damage to the plant. It looks like your Phal is in the house, though, so you need to find out how/where they're getting in and put down some ant powder.
Terro bait put between your Phal and where the ants are entering should help get rid of the ants. Examine the Phal and make sure the ants haven't started to farm mealy bugs/aphids/or scale on the orchid. Good luck!
You said the ants are *in* your Phal. Do you mean that they have made a nest inside the pot? If that is the case, just soak the pot in a bucket of water for a few hours. The ants will vacate the pot, taking as many larvae with them as they can. One time should do it, but if you feel like they're still there after a few days, it won't hurt to do it again.
If ants try to re-invade, you can also keep the pot in a saucer of water (raised, so that the roots aren't touching it). A little dish soap might help.
Ants infamously farm sap-sucking insects . Look closely for scale, mealy bugs or aphids. If you're lucky they are just after the plant's natural sap. However ants do carry insects from plant to plant so it's best to deter them.