Distribution of Specific Steam Loads in Tube Bundles of Condensers for Cogeneration Steam Turbines

Abstract

Results of experimental and numerical studies are presented on the steam distribution among the main bundles and the built-in bundle of condensers in cogeneration turbines using a specific steam load defined as the ratio of the amount of steam condensed in the bundle to the bundle surface area. The experiments agree well with the standard characteristics of the condenser. To calculate the specific steam loads in the condenser tube bundles, the manufacturing plant calculation procedure was updated. It allows for determining a steam flow rate in each tube bundle based on the condition of the same steam pressure in all the zones (tube bundles) of the condenser. It has been demonstrated that the specific steam loads of tube bundles can differ from each other by a factor of 20 or more and depend on the flow rates of steam and cooling water to the condenser, the water temperature at the bundle inlet, the number of water passes in the built-in bundle, and other factors. The effect of specific steam loads in tube bundles on the steam pressure in the condenser has been established to be considerable at steam flow rates close to the nominal values. One of the methods for improving the thermal performance of the built-in tube bundle for additional heating of make-up water, the application of profiled tubes, is examined. The obtained results are important from the standpoint of increasing the heat load of the built-in tube bundle (BB) when make-up water for the heating network is supplied through it and circulation water is fed through the main bundles (MBs) and of rising the oxygen content in the main condensate at the condenser outlet owing to condensate overcooling caused by nonuniform distribution of steam among tube bundles.