Heat ExchangersDOE-HDBK-1018/1-93HEAT EXCHANGER APPLICATIONSFigure 9 Single-Pass CondenserThere are different condenser designs, but the most common, at least in the large powergeneration facilities, is the straight-through, single-pass condenser illustrated Figure 9. Thiscondenser design provides cooling water flow through straight tubes from the inlet water boxon one end, to the outlet water box on the other end. The cooling water flows once through thecondenser and is termed a single pass. The separation between the water box areas and thesteam condensing area is accomplished by a tube sheet to which the cooling water tubes areattached. The cooling water tubes are supported within the condenser by the tube support sheets.Condensers normally have a series of baffles that redirect the steam to minimize directimpingement on the cooling water tubes. The bottom area of the condenser is the hotwell, asshown in Figure 9. This is where the condensate collects and the condensate pump takes itssuction. If noncondensable gasses are allowed to build up in the condenser, vacuum willdecrease and the saturation temperature at which the steam will condense increases.Non-condensable gasses also blanket the tubes of the condenser, thus reducing the heat transfersurface area of the condenser. This surface area can also be reduced if the condensate level isallowed to rise over the lower tubes of the condenser. A reduction in the heat transfer surfacehas the same effect as a reduction in cooling water flow. If the condenser is operating near itsdesign capacity, a reduction in the effective surface area results in difficulty maintainingcondenser vacuum.The temperature and flow rate of the cooling water through the condenser controls thetemperature of the condensate. This in turn controls the saturation pressure (vacuum) of thecondenser.Rev. 0ME-02Page 15
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