FLOW-PROMOTING DEVICES FOR OPEN, HEATED BOX TRAYS

A flow-promoting device in combination with a heated box tray open at the top in a reaction and degasification column in which a viscous or highly viscous liquid is flowing from an inlet end to an outlet end of the tray and in which a heating tube register is located to be completely covered by the liquid. The tube register includes a plurality of heating tubes spaced from each other, and the flow-promoting device has a bottom heating unit for the box tray positioned outside and along the bottom of the tray, a siphon plate mounted on the tray at a liquid inlet end of the tray and closely in front of the tube register, with the siphon plate having a bottom end extending to the underside of the tube register, and a weir positioned at the liquid outlet end of the box tray. The weir has a top edge extending at least to the topside of the tube register, and the spacing of the weir from the tube register is larger than the spacing of the siphon plate at the inlet end from the tube register.