Heat exchanger having intermittently movable rotational cleaning arms

A heat exchanger for exchanging heat between a first medium and a second medium, one of the media including incrusting substances, comprising a pair of end walls, one of the end walls having an inlet for the first medium and the other end wall having an outlet for the first medium;

• a rotary shaft extending between the end walls;
• means for rotating the shaft so as to drive the shaft intermittently at preselected intervals of operation;
• a plurality of disc-shaped hollow members each having a central passage for the shaft and a through opening located on a side of the passage, the through opening being sealed from the interior of the member;
• said disc-shaped hollow members having an inlet and an outlet for the second medium;
• cleaning arms non-rotatably connected to and extending radially from the shaft, a cleaning arm and a member alternating between the first and second end walls such that each of the cleaning arms by rotation of the shaft moves either between adjacent members or between an end wall and a member adjacent to the respective end wall wherein the openings of two of said adjacent members are offset by 180.degree. about the shaft in relation to each other;
• and, the cleaning arms in an inoperative state extending substantially centrally over the opening of the respective member whereby an area of the opening of substantially equal size is located on each side of the cleaning arm.