The integration of supercritical CO2 Brayton power cycles with existing industrial heat and power steam cycles can potentially increase thermal efficiency and net power output. However, it may also present specific operational challenges, due to the changes in the flue gas temperature distribution and fuel firing rate. In this paper, a steady-state 1D thermofluid model is used to investigate the impact of integrating an sCO2 heat exchanger within an existing biomass-fired boiler of a heat and power steam cycle. The model is based on a network approach where the mass, energy, momentum, and species balance equations are solved in an integrated manner together with individual component characteristics and fluid properties. The boiler model includes the combustion air and flue gas streams, the complete water/steam flow path, and the sCO2 flowing through the heat exchanger. The models account for the complex interaction among the heat transfer phenomena, including direct radiation, gas radiation, convection, and conduction for various boiler heat exchangers. The model was applied to evaluate the integrated cycle for the 60% and 100% load cases, with and without the sCO2 heater integrated into the gas flow path. Overfiring of the boiler is required to compensate for the additional heat extraction to the sCO2. The results show that heat exchangers downstream of the sCO2 heater are adversely affected due to the reduced flue gas temperatures. The control is also impacted with less attemperation required between the superheaters. The model can be used in future to analyse various heater configurations, as well as to study the integration of a complete Brayton cycle.