Tempdb is getting full very quickly in microsoft sql server 2008
Tempdb is growing like this because something is using it.  No attempt to fix, clean or manipulate tempdb is going to work as long as this is going on.

To address this problem, you need to find out what is causing it to grow like this and then fix that problem first.  This alone may resolve the whole issue and remove your need to do anything else with tempdb.  In my experience, the most likely cause for something like this is an out-of-control Cross Join query (though there are lots of other possibilities).