Looks to me like to me like one or two BLEVE’s. That’s a Boiling Liquid Expanding Vapor Explosion. Basically, it’s when a liquid storage vessel over-heats and ruptures... The sudden loss of containment causes the liquid to rapidly expand into a vapor cloud, which then explodes.
They can be devastating.
Tianjin was a major source of chemical shipment in and out of China. There’s no telling what all might have been stored there. And, let’s just say.... Their safety standards are not “quite” as stringent as ours.
This event will cause a disruption in chemical transport and supply.
As a container port, the possibility exists that it may have been a dirty bomb inside a container. The mooselimbs would love to send us one from China to start it all.
BLEVE is quite plausible, but the shape of the blast wasn’t linear enough (assuming cylindrical high pressure storage vessel with thinner end caps like we use here). Then again, Chinese steel and welding..... You’re probably right.
The reported use of water by the firemen would have gone far to increase the vapor, not to mention any adverse reactions to the chemicals ...