In view of the design problem of cooling steam in low pressure(LP) cylinder cutting technology of supercritical 350 MW units

by using the thermodynamic design calculation method of steam turbine

the temperature distribution at outlet of each stage blades of the low pressure cylinder under different cooling conditions and normal operation conditions was calculated in detail

and the relationship between the outlet temperature of low pressure cylinder with the cooling steam volume and steam temperature was obtained. The results show that

the final stage blade is in the state of blowing

and the exhaust temperature of the low pressure cylinder is linear with the cooling steam flow rate and the cooling steam temperature. It is negatively related to the cooling steam flow rate and positively correlated with the cooling steam temperature. Therefore

the outlet temperature of the last two stage blades can be effectively controlled by setting the cooling steam flow rate and temperature reasonably. This paper provides theoretical basis for design of the cooling steam of low pressure cylinder when the low pressure cylinderis is resected of the unit

and also provides the corresponding safety theoretical support for cylinder cutting.