Abstract: The concept of deep reducing the outlet gas temperature was introduced. The internal relation between the deep reducing the outlet gas temperature and the chimney corrosion prevention was analyzed. The evaluation of the additional cold source loss of the steam turbine in the deep energysaving system was discussed; and the key technology of heating surface corrosion prevention design was researched, here the corrosion is caused by the lower outlet gas temperature. It was pointed out finally that the scheme of deep reducing outlet gas temperature must be formulated according to the practical situation of the unit to get the maximum of the increased electricity.

Key words: boiler of power plant, deep energy conservation, outlet gas temperature, cold source loss