STEAM SURFACE CONDENSER OPERATION
The main heat transfer mechanisms in a surface condenser are the condensing of saturated steam on the outside of the tubes and the heating of the circulating water inside the tubes. Thus for a given circulating water flow rate, the water inlet temperature to the condenser determines the operating pressure of the condenser. As this temperature is decreased, the condenser pressure will also decrease. As described above, this decrease in the pressure will increase the plant output and efficiency. Due to the fact that a surface condenser operates under vacuum, noncondensable gases will migrate towards the condenser. The noncondensable gases consist of mostly air that has leaked into the cycle from components that are operating below atmospheric pressure (like the condenser). These gases can also result from caused by the decomposition of water into oxygen and hydrogen by thermal or chemical reactions. These gases must be vented from the condenser for the following reasons: The gases will increase the operating pressure of the condenser. Since the total pressure of the condenser will be the sum of partial pressures of the steam and the gases, as more gas is leaked into the system, the condenser pressure will rise. This rise in pressure will decrease the turbine output and efficiency.

• The gases will blanket the outer surface of the tubes. This will severely decrease the heat transfer of the steam to the circulating water. Again, the pressure in the condenser will increase.
• The corrosiveness of the condensate in the condenser increases as the oxygen content increases. Oxygen causes corrosion, mostly in the steam generator. Thus, these gases must be removed in order to extend the life of cycle components.
SURFACE CONDENSER OPERATION
STEAM SURFACE CONDENSER AIR REMOVAL
The two main devices that are used to vent the noncondensable gases are Steam Jet Air Ejectors and Liquid Ring Vacuum Pumps. Steam Jet Air Ejectors (SJAE) use high-pressure motive steam to evacuate the noncondensables from the condenser (Jet Pump). Liquid Ring Vacuum Pumps use a liquid compressant to compress the evacuated noncondensables and then discharges them to the atmosphere. To aid in the removal of the noncondensable gases, condensers are equipped with an Air-Cooler section. The Air Cooler section of the condenser consists of a quantityof tubes that are baffled to collect the noncondensables. Cooling of the noncondensables reduces their volume and the required size of the air removal equipment. Air removal equipment must operate in two modes: hogging and holding. Prior to admitting exhaust steam to a condenser, all the noncondensables must be vented from the condenser. In hogging mode, large volumes of air are quickly removed from the condenser in order to reduce the condenser pressure from atmospheric to a predetermined level. Once the desired pressure is achieved, the air removal system can be operated in holding mode to remove all noncondensable gases.

STEAM SURFACE CONDENSER CONFIGURATIONS
Steam surface condensers can be broadly categorized by the orientation of the steam turbine exhaust to the condenser. Most common are side and down exhaust. In a side exhaust condenser, the condenser and turbine are installed adjacent to each other, and the steam from the turbine enters from the side of the condenser. In a down exhaust condenser, the steam from the turbine enters from the top of the condenser and the turbine is mounted on a foundation above the condenser. Condensers can be further delineated by the configuration of the shell and tube sides.
Tubeside
The tubeside of a steam surface condenser can be classified by the following:
• Number of tubeside passes
• Configuration of the tube bundle and waterboxes
Most steam surface condensers have either one or multiple tubeside passes. The number of passes is defined as how many times circulating water travels the length of the condenser inside the tubes. Condensers with a once-through circulating water system are often one pass. Multiple pass condensers are typically used with closed-loop systems. The tubeside may also be classified as divided or non-divided. In a divided condenser, the tube bundle and waterboxes are divided into sections. One or more sections of the tube bundle may be in operation while others are not. This allows maintenance of sections of the tubeside while the condenser is operating. In a non-divided tubeside, all the tubes are in operation at all times.
Shell side
The shell side of a steam surface condenser can be classified by its geometry. Examples of types are:
• Cylindrical
• Rectangular