This seems unlikely. Officially, they had 2750 tones of ammonium nitrate on that dock. Even if it were properly mixed with fuel oil to make ANFO, that would give you 2200 tones of tnt equivalent. It is quite unlikely that it was mixed to the perfect proportions, so we’d expect actual yield to be below theoretical max So unless if something else was involved (or the official amount of ammonium nitrate was wrong) I wou…
There are plenty of petroleum distillates in a dockyard. Diesel, bunker fuel, kerosene, gasoline....not to mention other flammable hydrocarbons and powders. You're assuming an 80% ratio ANFO/TNT but you're neglecting the mass of the FO, as well as the possibility of other oxidizers being stored near the blast site. I guess you could make some assumptions about the fuel based on detonation velocity as observed on vide…
However, we know that the explosion wasn't stoichiometrically perfect, because of the brown NO2 clouds that were hanging over Beirut. Properly mixed ANFO should release only H2O, CO2, and N2. So we know that there was some level of explosive power that wasn't fully consumed. This is why I put the ANFO yield as the absolute theoretical max, I think in reality the actual yield was much much lower.
Some other people have speculated that the fireworks like mini explosions between the first and second big explosions was actually ammonium nitrate decomposing, which would imply that this was a pure ammonium nitrate explosion and not one accelerated by some sort of oil or other fuel. If that's true, various manufacturers give the AN to TNT equivalent of poorly handled AN at 15-40% of TNT, giving a yield somewhere in the 412-1,100 tonne range.