Decoupling Investigation of Furnace Side and Evaporation System in a Pulverized-Coal Oxy-Fuel Combustion Boiler

A distributed parameter model was developed for an evaporation system in a 35 MW natural circulation pulverized-coal oxy-fuel combustion boiler, which was based on a computational fluid dynamic simulation and in situ operation monitoring. A mathematical model was used to consider the uneven distribution of working fluid properties and the heat load in a furnace to predict the heat flux of a water wall and the wall surface temperature corresponding to various working conditions. The results showed that the average heat flux near the burner area in the air-firing condition, the oxy-fuel combustion with dry flue gas recycling (FGR) condition, and the oxy-fuel combustion with wet flue-gas recycle condition were 168.18, 154.65, and 170.68 kW/m2 at a load of 80%. The temperature and the heat flux distributions in the air-firing and the oxy-fuel combustion with wet FGR were similar, but both were higher than those in the oxygen-enriched combustion conditions with the dry FGR under the same load. This study demonstrated that the average metal surface temperature in the front wall during the oxy-fuel combustion condition was 3.23 °C lower than that under the air-firing condition. The heat release rate from the furnace and the vaporization system should be coordinated at a low and middle load level. The superheating surfaces should be adjusted to match the rising temperature of the flue gas while shifting the operation from air to oxy-fuel combustion, where the distributed parameter analytical approach could then be applied to reveal the tendencies for these various combustion conditions. The research provided a type of guidance for the design and operation of the oxy-fuel combustion boiler.

[1]  R. Laubscher,et al.  Heat transfer modelling of semi-suspension biomass fired industrial watertube boiler at full- and part-load using CFD , 2021 .

[2]  R. Laubscher,et al.  Integrated mathematical modelling of a 105 t/h biomass fired industrial watertube boiler system with varying fuel moisture content , 2021 .

[3]  Joon Ahn,et al.  Combustion Characteristics of 0.5 MW Class Oxy-Fuel FGR (Flue Gas Recirculation) Boiler for CO2 Capture , 2021, Energies.

[4]  Zeenathul Farida Abdul Gani,et al.  Modelling of coal combustion in a drop tube furnace in air and oxy fuel environment , 2021 .

[5]  Shaolin Liu,et al.  Calculation method of gas–liquid two-phase boiling heat transfer in helically-coiled tube based on separated phase flow model , 2020 .

[6]  Matheus dos Santos Guzella,et al.  Simulation of Boiling Heat Transfer at Different Reduced Temperatures with an Improved Pseudopotential Lattice Boltzmann Method , 2020, Symmetry.

[7]  T. Wetzel,et al.  Flow-pattern based prediction of flow boiling heat transfer in horizontal tubes with circumferentially varying heat flux , 2020 .

[8]  R. Laubscher,et al.  CFD study of pulverized coal-fired boiler evaporator and radiant superheaters at varying loads , 2019, Applied Thermal Engineering.

[9]  Hairui Yang,et al.  Thermal-hydraulic calculation and analysis on evaporator system of a 660 MWe ultra-supercritical CFB boiler , 2019, Applied Thermal Engineering.

[10]  Shuiqing Li,et al.  Measurements and modelling of oxy-fuel coal combustion , 2019, Proceedings of the Combustion Institute.

[11]  C. Béguin,et al.  Two-phase flow pattern identification in a tube bundle based on void fraction and pressure measurements, with emphasis on churn flow , 2017 .

[12]  Chuguang Zheng,et al.  Experimental and numerical investigations on oxy-coal combustion in a 35 MW large pilot boiler , 2017 .

[13]  Ping Xu,et al.  Numerical investigation on oxy-combustion characteristics of a 200 MWe tangentially fired boiler , 2015 .

[14]  Zhou Huai-chun,et al.  Development of a distributed-parameter model for the evaporation system in a supercritical W-shaped boiler , 2014 .

[15]  Lin Ma,et al.  Effects of firing coal and biomass under oxy-fuel conditions in a power plant boiler using CFD modelling , 2013 .

[16]  Gautham Krishnamoorthy,et al.  A comparative evaluation of gray and non-gray radiation modeling strategies in oxy-coal combustion simulations , 2013 .

[17]  Xiangyu Zhang,et al.  Distributed parameters modeling for evaporation system in a once-through coal-fired twin-furnace boiler , 2011 .

[18]  Xiaojin Huang,et al.  A lumped parameter dynamic model of the helical coiled once-through steam generator with movable boundaries , 2008 .

[19]  Qiang Cheng,et al.  Distributed parameter modeling and simulation for the evaporation system of a controlled circulation boiler based on 3-D combustion monitoring , 2008 .