An Analysis of the Influence of Multilayer Films with Low Thermal Conductivity on the Inner Surfaces of CCPP Headers and Steam Pipelines on Their Thermal Stress State

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An Analysis of the Influence of Multilayer Films with Low Thermal Conductivity on the Inner Surfaces of CCPP Headers and Steam Pipelines on Their Thermal Stress State

March 6, 2021 Chemical Science 0

The outlet high-pressure superheater header is one of the most important critical elements affecting the resource of combined cycle power plants (CCPP) heat recovery steam generators (HRSG). Maintaining the proper water-chemical regime, which causes the formation of thin protective films, protects headers, heat-exchange valves, and steam pipelines from corrosion. The combination of a protective film layer and a layer of heating steam condensate on the inner surface of pipelines with a heat carrier flowing inside, for example, provides a major thermal resistance of the multilayer wall and helps to minimise thermal stresses that arise in them under variable conditions. At temperatures above 230°C and good deaeration, these protective films, which protect pipes from corrosion, form on the inner surfaces of CCPP heat recovery steam generators pipe systems. The results of a computational study of the effect of thin multilayer protective films on the thermal stress state of CCPP HRSG headers and steam pipelines under various variable operating conditions, in particular during start-ups from various thermal states and thermal shocks, are presented in this paper. Calculations were conducted at various film thicknesses and with the assumption that their thermal conductivity is lower than that of the base metal. It was possible to decide the heating modes of headers and steam pipelines, on which the protective films have the greatest power, as a result of the calculations. Multilayer protective films are shown to have a noticeable impact on the stresses that arise in the pipe and the accumulation of damage, particularly when large temperature fluctuations occur (during thermal shocks). Under variable modes, the effect of protective films on the thermal stressed condition of non-heated pipes was evaluated in terms of reducing resource consumption and accumulating equal operating hours. It has been demonstrated that the resource of a high-pressure superheater outlet header 426 x 34 mm can be increased by 6% simply by adding a protective film Fifty microns thick with a thermal conductivity equal to half that of the base metal.

Author (s) Details

Yury. A. Radin
JSC “Mosenergo”, Moscow, Russia.

Tatiana. S. Kontorovich
JSC “Mosenergo”, Moscow, Russia.

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