An arrangement is proposed for preventing or removing blockages in essentially vertically arranged enclosed spaces such as for example cyclone heat exchangers for the cement industry. In the region of the outlet of the closed space, a tool is provided, which can be introduced translationally and periodically from outside into the inner region of the outlet. The translation movement is performed in a pulsating manner by means of a pneumatic cylinder, a rotation movement being superposed on the translation movement. <IMAGE>
