I realize that I probably misinterpreted your problem. I supposed that your 2D array was a 2D string array, and gave a straighforward solution.
Could you just precise what kind of data you have in your array (1D array of alphanumerical data separated by tabs ?) (you could post an example) and also what is the purpose of replacing Tab by Space (display, file saving, something else ...)?
Chilly Charly (aka CC)