7.1 Condenser air inleakage
Techniques used for the location of leaks are outlined, and methods for measuring the rate of air inleakage in condensers are described.
The reasons why it is desirable to minimise air inleakage are:
- To improve condenser heat transfer performance.
- To reduce the capital cost of the air extraction equipment required.
- To reduce air extraction plant running costs.
Tests have indicated that with well ventilated condenser tubenests, air inleakage within the capability of the air extraction plant installed (100-200 kg/h for 500 MW units) does not adversely affect the condenser heat transfer performance. The objectives for minimising air inleakage rates on new condensing plant are, therefore, aimed at reducing capital costs and running costs.
Operational levels of air inleakage, however, vary between different station designs. For example, stations with underslung condensers and indirect feedheating plant have an advantage over stations with pannier condensers and direct-contact feedheating plant.