The structure of the bubble cap tray is mainly composed of a blister (gas-liquid contact element), a gas riser, an overflow weir, a downcomer and a tray.

The bubble tray is provided with a plurality of round holes on the tray plate, and each hole is welded with a short tube called a riser tube, and the tube is covered with a “hat” called a blister, and a plurality of strips are formed around the blister. Hole, during operation, the liquid flows from the upper tray through the downcomer into the lower tray, then flows laterally through the tray plate and flows into the next tray; the gas rises from the lower tray into the riser tube and passes through the annular passage. The strip holes of the blister flow into the liquid layer between the blister.