As an old steam engineer, let me say this: There is no excuse for an oil-fired warship in good condition to send up black smoke, especially in this quantity.
Shit, coal-fired ships often didn't smoke that badly.
The smoke suggests to me that either the plant design or the snipes of the Admiral Kuznetsov suck. Proper naval boilers have economizers; the hot flue gasses from the boiler fires pass over the economizer tubes to pre-heat the feedwater prior to it being fed into the boiler. The fuel savings of economizers are significant, something like 10%, but that level of efficiency can't be achieved if the economizer tubes and their vanes are covered with soot.
Even if the ship was "blowing tubes" (using steam to blow the soot from boiler tubes), for that much soot to be blown off indicates that the plant is running too rich a mixture. There should be no smoke visible from a properly-fired naval boiler.
This article may overstate things, but I am prepared to believe that the Kuznetsov is a piece of shit.
10 hours ago