A sponge rubber ball serves for tube cleaning and is used for removing fouling from the tubes of shell-and-tube heat exchangers in general and from the cooling tubes of condensers in particular. For this purpose the ball is used in quantities from 20 to up to several thousands, depending on the special application, in the so-called Taprogge System. The sponge rubber ball is added to the cooling water flow via a special ball injection and is transported through the tubes to be cleaned by the cooling water. At the other end of the condenser there is a strainer in the same nominal diameter as the cooling water pipe by means of which the balls can be separated again from the cooling water flow. A rotary pump looks after the transport of the balls back to the ball injection point – and we've come full circle. Under normal conditions the balls can remain in use for a maximum four weeks.
Sponge rubber balls are produced in diameters from 10 mm to 45 mm. They are made of biodegradable natural rubber which is worked in a vulcanizing process. In the course of vulcanizing the balls get their diameters and further desired properties:
Decisive for the effectiveness of the cleaning is a ball diameter that is adjusted to the tube, as well as the surface property of the cleaning ball. The buoyancy has an influence on the distribution of the balls to the individual tubes of the tube bundle. During production various dyes are added which mark the ball properties.
To improve the cleaning effect, the balls can be provided with a coating. If particularly hard scales have to be removed, corundum is used as coating material. Another addition is pumice which removes surface roughness in the tubes through polishing. Other added substances improve the temperature resistance of the balls, so that they can be applied in the heat exchangers of seawater desalination plants.
The definition of the size of the sponge rubber ball and of its further properties depends on a multitude of parameters and should always be made by the producer.