A plate used in an item of equipment to influence the rate or direction of a flow of material. The plate may be flat or curved and used in vessels such as tanks or heat exchangers to increase turbulence or prevent the formation of a vortex. An impingement baffle is (p. 25) used to minimize the disturbance of a liquid–liquid interface in a decanter device and can also be used in shell and tube heat exchangers to reduce the effects of erosion by forcing a vapour stream around the baffle causing any liquid drops to collide with the baffle.

Baffles are often used in shell and tube heat exchangers to direct the fluid stream across the tubes to increase the fluid velocity and increase the rate of heat transfer. The baffle is a circular plate that is similar in size to the tube plate with many holes through which the tubes fit. A segmental baffle allows the shell-side fluid to move under the baffle or over the baffle through the segmental space (see Fig. 5). The baffle cut is the segment height removed to form the baffle, expressed as a percentage of the baffle disc diameter. The baffle spacing is the distance between the baffles.

Fig. 5