There usually aren't completely instrumental blues albums (like, every song is an instrumental). Completely instrumental albums usually deviate from blues, as well. I could, for example, recommend Buckethead albums but it would be a stretch to call them "blues guitar" albums. I guess I'll recommend songs instead.
Most of Jeff Beck's work is instrumental. I recommend Cause We've Ended As Lovers.
Stevie Ray Vaughan's rendition of Little Wing is completely instrumental.
The song Blue Monday by White Lion is a great blues guitar song. Unfortunately, Vito Bratta isn't active anymore because of a hand injury.
Joe Bonamassa's rendition of Just Got Paid has very limited vocals and is almost completely instrumental.
Blues usually features vocals, man. It's an integral part of its history and culture. I would recommend songs like Since I've Been Loving You (Led Zeppelin), La Grange (ZZ Top), Pride and Joy (SRV), and Voodoo Child (Jimi Hendrix) where there are vocals but the songs' main features are lengthy guitar work.
On a side note, I heavily recommend Parisienne Walkways (Gary Moore) for string bending and vibrato practice.