Heat exchanger or condenser tubes will become fouled over time. Often times, deposits like algae, mud, slime, silt, barnacles, mussels, biofouling, and (light) scaling will adhere to the tube walls. By doing so, they create an isolating barrier which negatively impacts the heat transfer coefficient. In other words, the system’s performance will decrease due to deposits inside the tubes. Even heat exchangers with automatic (online) ball cleaning systems will become fouled over time. An offline cleaning will be necessary to get the tubes clean again.

After deciding to perform an offline cleaning to restore efficiency levels, it is possible to choose from different cleaning technologies. Dart cleaning is a safe, fast, and cost-effective technology to clean heat exchanger and condenser tubes. When cleaning with projectiles, it is important to have all the necessary data at hand, such as the expected deposits, tube material, inner diameter, and length. It’s also good to know what kind of cleaning (if any) has taken place in the past.

When all data has been collected, it is time to choose the right type of projectile which will be used to shoot through the tubes and remove the deposits. The experts of Abalco’s DCS team are able to assist with recommendations based on your information and our experience. Projectiles are reusable and travel through the tubes at high speed. Often times, they remove all deposits inside the tube within a single pass.

Projectiles are loaded into the tubes and shot through with specialized equipment, also known as propulsion systems. These systems use a high waterflow of ca. 130 liters/minute to push the projectiles through the tubes. The high waterflow also causes turbulence inside the tubes, which increases the cleaning effect and also flushes out loosened deposits. The entire cleaning process is performed with a low pressure of only 40 bar, which greatly contributes to the safety of the operators and equipment.

A special catching net is attached to the other side of the heat exchanger or condenser. This net is used to catch the projectiles when they exit the tubes. By catching the projectiles safely, maximum reusability is ensured. After projectiles are caught and cleaned, they can be reused. The amount of times a projectile can be used, depends on the type, tube length, deposits, etc. More information can be found on the ”projectiles” page.

After cleaning, it is important to inspect all tubes for potential blockages or stuck projectiles. By performing a light test, a large number of tubes can be inspected in a short period of time. Often times a blockage is just a tube that had been missed during cleaning. By flushing it, the blockage or stuck projectile is often removed right away. In case this doesn’t work, the deposit/projectile can be pushed out with a fiberglass rod.

When the cleaning and inspection has been completed, the heat exchanger or condenser can be returned to service. With the tubes now being clean, it is wise to consider implementing a preventive mechanical tube cleaning strategy. For example, every 1 or 2 years the heat exchanger or condenser is cleaned with projectiles, ensuring maximum efficiency and less hard deposit buildup over time. Furthermore, by doing this, potential tube leaks caused by under deposits- or microbiologically induced corrosion is prevented as much as possible.