The Portugal Under-21 striker leaves Everton after two years with the Club.
In that time he has featured for the reserve team, but departs without having made a first-team appearance.
Silva was signed from Portuguese second tier side Desportivo Das Aves in June 2010 after 14 goals in 32 appearances convinced the Club to bring him to England.
The 6ft 2in left-footed frontman had caught the attention of teams in Portugal's top flight before he switched to Merseyside.
Loan spells with Uniao Desportiva de Leiria and Vitoria FC took him back to his homeland before the Blues decided to accept an offer from Bulgarian outfit Levski.
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