The problem of the surface condenser overall heat transfer coefficient determining at high temperatures of cooling water

Abstract

The article presents a comparison of the real overall heat transfer coefficient, based on thermal tests of the condenser of the steam turbine PT-25-90 KTZ during off-design operation (with a degraded vacuum) and its expected value, calculated via the Metropolitan Vickers formula. The average cooling water inlet temperature was 61.2 °C, average exhaust steam pressure was 0.542 bar during thermal tests. The average deviation of the expected overall condenser heat transfer coefficient from the real value was 27,18%. The calculations showed a higher difference between the real and expected value at the regimes with low cooling water velocity and with high exhaust stem pressure. The obtained results showed the need to refine the methodology of the condenser's overall heat transfer coefficient calculation in the degraded vacuum mode. This can be done by adding correction factors to the water temperatures that are typical for the degraded vacuum regime.

Keywords

• Condenser
• Steam turbine
• Thermal test
• Cooling water
• Heat transfer coefficient
• Energy infrastructure