The following is my route around the site. My realtime audio recording is here:
Download TorranceExplosion (yeah I know I said the wrong date at the end. Today is the 18th not the 17th.) I drove clockwise around the refinery. My route is the yellow line. The large damaged building is the red rectangle. The police checkpoints are the blue squares.
This is the best picture I have seen illustrating the damage done to that large building. It's an angle looking northwest from about Del Amo & Crenshaw. That's a big building. Credit to SoCalPix
Actually, this one is even better and shows that the explosion went clearly through the entire structure. As you can see, this building is a good 12 stories high. The unit is an electrostatic precipitator. My guess is that it is a wet setup owing to the steam that is visible. It's basically a very large air pollution device. It conforms with my experience of smelling hydrogen sulfide on that stretch of Crenshaw.