Model cieplno - przepŁywowy przegrzewacza pary w kotle energetycznym

In multistage superheater systems between the furnace and the convective pass of the power boiler there are often located platen radiant superheaters. From standard in-line tube banks they differ in relative tube spacings, and in layout of headers. Such design prevents the slagging of convection tube bundles with narrow spacings and is favourable in view of the radiation heat transfer efficiency. In the range of flue gas temperatures of about 900 - 1300°C, corresponding with the end of furnace, this heat transfer mode dominates. The paper presents the model of flow and temperature distribution in the superheater of a power boiler. The calculation method has been presented, determining the steam enthalpy increase in the chosen tube of platen superheater as well as the evaluation of influence of the variability of specific heat of superheated steam (c_p) on the results of calculation of temperature distribution in the surface. It has been evaluated, on the basis of two actual examples, to which extent it is possible to use the simplified models neglecting the variability of c_p.