7 Trumpets of REVELATION SERIES: Opening Scene

And I saw the seven angels which stood before God; and to them were given seven trumpets.

And another angel came and stood at the altar, having a golden censer; and there was given unto him much incense, that he should offer it with the prayers of all saints upon the golden altar which was before the throne. 

And the smoke of the incense, which came with the prayers of the saints, ascended up before God out of the angel's hand. 

“Christ proclaims Himself our Intercessor. He places His merit in the golden censer to offer up with the prayers of His saints, so that the prayers of His dear children may be mingled with the fragrant merit of Christ as they ascend to the Father in the cloud of incense.” E.G.W.

And the angel took the censer, and filled it with fire of the altar, and cast it into the earth: and there were voices, and thunderings, and lightnings, and an earthquake. And the seven angels which had the seven trumpets prepared themselves to sound.
Revelation 8:2-6

The fire is a symbol of the Holy Spirit and 

the incense represents the prayers of the saints 

mingled the merits of Jesus.

Drawn/taken from the book Daniel & Revelation by Uriah Smith---Study Guide by Stephen Bohr---Sermon by Walter Veith---Commentaries from Matthew Henry/Adam Clark---Revelation Made Clear