Fantasma
Mechanical
- Jan 22, 2003
- 1
I have always accepted that increasing air leakage into a condenser leads to subcooling of the condensate in accordance with Dalton’s Law of Partial Pressures. A recent turbine-generator test series included an output test at a simulated high cooling water temperature. The method chosen for the simulation was to bleed air into the unit to increase the condenser pressure. The apparent subcooling in the condenser decreased from about 2F at 2.25”Hg for normal operation to about 1F at 3.75”Hg at the test conditions. Dalton’s Law is obviously not applicable to this arrangement; does anybody know why and what is happening?
The condenser is a transverse, underslung, twin shell, tubular surface type. The instrumentation was unchanged for the tests at the two different operating conditions. Pressure measurement was by 0.1% pressure transducers, with one connected at each side of each LP turbine exhaust duct. A platinum resistance thermometer, directly immersed in the condensate, measured the temperature in the bottom of each condenser. Data from tests on other similar units showed a similar effect. Some of the units had air admitted directly into the air pump suction through the vacuum-breaking valve. The air was admitted into the other unit through spare connections next to the turbine to condenser joint. This suggests that the location of the air bleed may not have a significant effect on what is happening.
The condenser is a transverse, underslung, twin shell, tubular surface type. The instrumentation was unchanged for the tests at the two different operating conditions. Pressure measurement was by 0.1% pressure transducers, with one connected at each side of each LP turbine exhaust duct. A platinum resistance thermometer, directly immersed in the condensate, measured the temperature in the bottom of each condenser. Data from tests on other similar units showed a similar effect. Some of the units had air admitted directly into the air pump suction through the vacuum-breaking valve. The air was admitted into the other unit through spare connections next to the turbine to condenser joint. This suggests that the location of the air bleed may not have a significant effect on what is happening.