Mechanical engineer Roy Keld, originally of Sedgefield, lives about 1.5 miles (2km) from the blast site with his Chinese wife and son.
He said it was a scene of "total devastation".
More than 700 were injured and hospitals are struggling to cope.
The first explosion happened at 23:30 local time (15:30 GMT) on Wednesday in an industrial zone home to car factories, aircraft assembly lines and other manufacturing and research firms.
Mr Keld said: "My wife and I felt several shockwaves. We thought it was initially thunder then a much stronger one blew several of our windows open.
"Stupidly, I started to close the windows just as a fourth and even stronger blast or shockwave hit our apartment block. The window I was closing blew open again, hitting me in the face and knocking me to the floor.
"I got two black eyes and a bloody nose. I think in retrospect I got off very lightly considering what's happened to the area. It's just total devastation."
Mr Keld has lived in China for six years as an employee of a UK company called Heat Tech Tooling, which has its Tianjin facility about 25 miles (40km) from the blast site and has been unaffected.
The China Earthquake Networks Centre said the magnitude of the first explosion was the equivalent of detonating three tonnes of TNT, while the second was the equivalent of 21 tonnes.
Mr Keld continued: "We took our son and evacuated into the street, which was rapidly filling up with people.
"The reports started coming through that it was an explosion. Nobody was panicking but there was a lot of confusion and wanting to know what was going on.
"There were a lot of sirens, emergency services going down and we had to decide what to do.
"Driving out of TEDA (Tianjin Economic-Technological Development Area) this morning we passed a long line of emergency vehicles going the other way."
As a precaution Mr Keld and his family have moved to a hotel 30 miles (48km) from the blast site, but he said he hopes they will be able to return home "within the next few days".
A British man living in the Chinese city of Tianjin has spoken of chaos and confusion following several major explosions that have killed at least 50 people.