Abstract: The 2×330MW cogeneration unit of a power plant was taken as research object. The key technical problems about the selection of the pipe lowing scheme of the unit, the pipe blowing process flow and the matters needing attention in pipe blowing process were researched and analyzed. The practice shows that this task of pipe blowing had been accomplished successfully，and the expected effect was realized. The common problems in pipe blowing process, such as overtemperature of the heating surface and heating of the reheater without steam, were avoided.
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Key words: subcritical boiler, cogeneration unit, pipe blowing, key technical point