Condensers remove heat from steam exhausted in the electricity generation process using cooling water. This maintains the pressure gradient exiting the turbine. However, the surfaces of condensers can be polluted by contaminants within the cooling water stream.
Over time, these contaminants can build up on the condenser tube surface and reduce the heat transfer properties of the condenser. This reduces steam turbine efficiency and increases energy consumption.
Generally, condenser tube cleaning is carried out during a turbine maintenance outage. For a large coal-fired plant this occurs every few years. For plants where condenser fouling is a significant issue, monitoring of condenser back-pressure and cooling water and steam temperatures can indicate that on-line cleaning is required.
Off-line cleaning during an outage can be done with high-pressure water jets or mechanical tube cleaners that scrape the fouling loose from inside the tubes. On-line cleaning can be achieved by injecting plastic balls into the cooling water stream, which loosen fouling as they pass through the condenser tubes. Cleaning condensers can also improve detection of leaks.
Sectors and common applications
- Electricity generation sector − steam turbine outlet
- Estimated energy savings in 2014 across the sectors were 18 PJ/pa.
|1. Energy saving and cost achievement|
|1.1 Energy saving||9/15|
|1.2 Cost effectiveness||6/10|
|2. Market contexts|
|2.1 Sector energy savings||5/10|
|2.2 % of industry $ gross added value||10/10|
|3. Originality and innovation|
|4.1 General applicability||4/5|
|4.2 Ease of implementation||5/5|
|4.3 Ability to integrate external resources||4/5|
|5.2 Social awareness||1/3|
A series of off-line condenser cleanings were undertaken by AGL Energy Ltd across all four units at one of their facilities. This was the first time cleaning had been undertaken passing a plastic ball through each tube. At the same time, the acid-dosing plant was re-established to redirect a drain line, which had been allowing dirty water to enter the cooling tower basin. Significant improvement in condenser performance was identified across all units.
Condensers at one of the Electricity Generation Corporation’s power stations were often experiencing high back-pressure problems, which caused a significant loss of energy and profit. The potential energy saving associated with condenser cleaning was 45 000 GJ and about 4,200 tCO2e abated, with annual net savings of $103 000. The payback period of an off-line cleaning cost is usually within two weeks of the unit’s return to service.
Other companies which have identified condenser cleaning as a source of energy savings include:
For more information:
Energy Efficiency Best Practice – Industrial Refrigeration (PDF, opens in a new window)