The Traditional Approach
- Conventionally, the ACCW is cleaned by an automated in built, externally mounted system.
- In addition to being relatively slow, there are areas of the units around the plenum internal finned surface periphery which it cannot reach at all, so it is difficult to restore commissioned air flow and therefore cooling performance.
- Blocked or restricted air flow can create a stall situation; where blown air cannot escape the plenum through the finned surface and therefore returns in the direction of the fan only to be recycled back toward the fins gaining temperature through each cycle, the result being a severe underperformance of the unit due to lack of cooling.
- Previous contractors employed by Scottish Power had not been able to clean the ACCW fin-fan cooling systems successfully.
- With the extensive experience of cleaning in-fan units of all sizes and configurations, Tube Tech assured Scottish Power that their ACCW's could be cleaned to a higher standard and faster than had previously been thought possible.
- The objective of the clean was to remove as much deposit as possible from the finned surfaces on both the internal and external of the plenums to improve air flow and therefore performance.
- To ensure that output from the power station could be maintained during cleaning, the ACCW units would remain on-line, with individual fans isolated and re-instated chamber-by-chamber as the cleaning progressed.
- To carry out the cleaning, Tube Tech used a custom-designed telescopic lance system. This enabled the team to work safely from the standard walkways inside the apexes of the fin-fan units - where the deposits accumulate the greatest while eliminating the need for costly scaffolding.