I am wanting to remove 9.5' of a 11.5' 2x4 wall on our first floor separating the kitchen from the dining room. The wal is load bearing, the 2x12 joist are spliced(run past wall 6" each side) I can put the one end on the exterior wall with a 4x4 down to foundation, and the other right on a beam( that's why I'm leaving the 2' piece. It's a bedroom above. Could I double up a 2x10with 1/2" ply between for that distance?

The size and type of beam would have to be approved by the building dept in your area. They will probably want a drawing by a certified architect or construction engineer.

Both sides of new girder have to be supported down to the foundation or a footing. A floor beam is not strong enough to support girder and may break from the extra weight.

Chuck