Simulation of heat transfer in combustion chamber waterwall tubes of supercritical steam boilers

Abstract

The paper presents the results of numerical computations performed for the furnace chamber waterwalls of a supercritical boiler with a steam output of 240010 3 kg/h. A model of distributed parameters is proposed for the waterwall operation simulation. It is based on the solution of equations describing the mass, momentum and energy conservation laws. The aim of the calculations was to determine the distribution of enthalpy, mass flow and fluid pressure in tubes. The balance equations can be brought to a form where on the left-hand side space derivatives, and on the right-hand side -time derivatives are obtained. The time derivatives on the right-hand side were replaced with backward difference quotients. This system of ordinary differential equations was solved using the Runge-Kutta method. The calculation also takes account of the variable thermal load of the chamber along its height. This thermal load distribution is known from the calculations of the heat exchange in the combustion chamber. The calculations were carried out with the zone method.

Analysis of thermal flow in waterwall tubes of the combustion chamber depending on the fluid parameters

“…In the following subsections, will be presented the equations describing the principles of mass, momentum, and energy conservation. Then, equations will be solved using the method proposed in [1]. S1336 THERMAL SCIENCE: Year 2019, Vol.…”

“…The equation of energy balance for the control volume can be written as a comparison of the internal energy, heat transfer and kinetic energy of the fluid. The initial equation is presented in [1], after its transformations, we can write the equation of energy balance:…”

“…The variability of thermal stresses in the tubes during operation after the start-up phase occurs from the transient conditions of the flow of the working fluid inside them and the uneven heat flux on the exchanger surface. The dependencies are allowing determining the pressure distribution and mass-flow of the working fluid, taking into account the type of the boiler, are presented in [1]. In this paper were presented the results of numerical calculations carried out using the Runge-Kutta method to solve a system of equations describing the behavior of energy, mass, and momentum.…”

Analysis of temperature drops on the wall thickness of a supercritical boiler water-wall tube

“…Various models describing the heat transfer in the supercritical power boiler evaporator can be found in literature, for example [1][2][3][4][5]. The model proposed in [1] is based on 3-D temperature distribution in the boiler furnace chamber.…”

“…S1091-S1100 drops for different operating conditions. Selected results of numerical computations performed for the furnace chamber water-walls of a supercritical boiler are presented in [3]. The developed mathematical model is based on equations describing the principles of mass, momentum, and energy conservation which are solved using the Runge-Kutta method.…”