| Cooling system maintenance
Figure 2. Different kinds of deposits in heat exchangers
Water gun with projectiles Cleaning of condenser tubes with projectiles ‘fired’ from a water gun is relatively easy, and less time consuming than high pressure water jet blasting. Various kinds of projectiles are available, depending on the nature of the deposits, scale or debris (see Figure 5). The risk of pipe damage is less than with high pressure water jet blasting but hard metal scrubber projectiles should only be deployed after careful consideration. EHS concerns are small compared with high pressure water jet blasting but, as with such blasting, water boxes need to be protected to avoid coating damage, and after the tubes are cleaned, the water boxes need separate cleaning.
Mechanical cleaning
Tubes can also be cleaned with brushes or drills, which is required when tubes are completely blocked and flow through them is not possible. Mechanical cleaning takes time as it is done tube-by-tube and requires manual supervision and operation.
Figure 6 shows a selection of cleaning brushes and drills which are available in different materials to match expected debris types and tube materials.
The risk of tube damage is high as the brush or drill centres itself on the tube’s internal diameter. This means that that drills and grinders need to have nearly the same dimensions as the inner diameter of the tubes to be cleaned, with only narrow clearances.
Chemical cleaning
Chemical cleaning is not very time consuming. The composition of the cleaning solution can be adapted to the deposits to be removed. This means that almost any kind of scale can be removed from tubes and water boxes. Heat exchangers and water boxes need to be filled completely with cleaning solution, and constant and even flow through all tubes must be assured, independent of tube location (upper, corner, etc), which requires high flow velocity and volume throughput (see Figure 7). Water boxes do not need separate cleaning, which can be counted as an advantage. However, the chemicals applied might raise EHS concerns and require special mitigations and safety measures.
Specific entropy (kJ/kg.K)
Figure 3. T–S (temperature–entropy) diagram for a steam power plant Carnot cycle 1: Condensation 1’: Condensation with fouled condenser tubes 2: Condensate and feedwater-prewarming 3: Evaporation in the boiler
4: Superheating 5: Expansion in the HP turbine 6: Reheating 7: Expansion in the IP turbine 8: Expansion in the LP turbine (steam wetness 10 – 15%)
www.modernpowersystems.com | March 2026 | 23
Absolute temperature (K)
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