Total Systems Approach to Condenser Oxygen Control as Applied to a Combined Cycle Cogeneration Power Plant
ABSTRACT
Amultifaceted approach to condenser design was applied to the Gilroy Foods Cogeneration Plant in order to optimize oxygen control. This unique design incorporated the following components:
• A vacuum deaerator to remove noncondensible gases from the makeup water. The deaerator is connected to the condenser through steam piping and a return line to the hotwell
• A segregated condensate reheat hotwell to further deaerate the water from both the condenser and the vacuum deaerator. Steam injected into the hotwell reheats the condensate and acts to scrub out any reabsorbed gases;
• An enhanced venting system ensuring that whatever noncondensible gases are released will be removed and which maintains a low air partial pressure within the condenser.
INTRODUCTION
Power plant designers, operators and manufacturers are only now beginning to appreciate the interrelationship between the condenser, the vacuum level, deaeration, and the system venting equipment. Low load operation with coincident low cooling water temperature requires a venting equipment modification to cope with operating pressures and increased water vapor carryover affecting both power train efficiency and condensate dissolved oxygen.
The Gilroy Foods Cogeneration Project offered an opportunity to apply several concepts of improved oxygen removal in the steam condenser. This plant has a wide range of operating conditions including severe, coincident parameters of low condenser load, low incoming water temperature, and high makeup water flow to the unit. Stringent oxygen removal requirements will have to be maintained under all flow conditions.