Abstract: A heating system for a spray dryer has a heating element, a heating unit having an open-pore metal foam, and a fluid input and a fluid output. The metal foam is arranged between the fluid input and the fluid output so that fluid which flows in through the fluid input and out through the fluid output is laminarized. A method for simultaneously heating and laminarizing a fluid with the aid of an open-pore metal foam is also disclosed, as is an electrostatic precipitator having a sleeve-shaped electrode connected to a base part of the precipitator. Also disclosed is a device for detaching particles from an inner surface of a sleeve-shaped electrode, a method for detaching particles, and a spray dryer with a heating system as above and/or with an electrostatic precipitator.