It will burn fine, but you must split even the smaller wood, the bark on hemlocks as with all pines has a fire retardant in the bark, to protect it in a forest fire.
Several years ago I had some scotch pines I cut to burn. I did not split them if they were over 4" diameter. When I put some into a roaring fire every other thing burnt up and at the end of the day, I still had a 4" chunk (Scotch Pine), blackened but still full size.