Analysis of the Design of a Thermal System for a 1350MW Secondary Reheat Power Generator Unit

With the design coordination between both sides of the boiler and steam turbine being taken into account in a comprehensive way,set up was a 1350 MW secondary reheat unit principle thermal system. For different configurations of the feedwater pump steam turbines,a calculation and analysis were performed with the influence of two versions of feedwater pump-purposed steam turbines on the reheat steam flow rate,heat rate of the unit and design of the reheater etc. being quantitatively analyzed,namely,back pressure and extraction type and condensing type steam turbine. It has been found that under the rated load operating condition,the steam flow rates of the primary and secondary reheater of the back pressure and extraction type feedwater pump steam turbine thermal system are 266 and289 t / h smaller than those of the condensing type one,thus making for the design of the convection heating surface of the boiler. Compared with the steam inlet temperatures of No. 4 and 5 heaters in the condensing type steam turbine system,those of the back pressure and extraction type steam turbine thermal system will lower by 350 and 297℃ respectively,favorable for the design and operation of the heaters. However,the heat rate of the back pressure and extraction type steam turbine thermal system version is 6 kJ / kW. h higher than that of the condensing type steam turbine thermal system version. Under the partial load operating conditions,the calculation results show that the primary and secondary reheat steam flow rates of the back pressure and extraction type steam turbine thermal system is still lower than those of the condensing type steam turbine thermal system and the heat rate of the former is still a bit excessively high.