Coupled modeling of combustion and hydrodynamics for a 600 MW Bunsen-type boiler

ABSTRACT

Hydrodynamic calculation is considered to be significantly important to ensure the safe operation of boiler during the peak-shaving process. An accurate furnace heat flux distribution is the basis for the accurate hydrodynamic calculation. To investigate the hydrodynamic characteristics of a 600 MW boiler, a coupled model that consists of combustion simulation and hydrodynamic calculation is applied in this study. The numerical simulation could provide the distribution of the furnace heat flux as a preparation for the hydrodynamic calculation. Results show that the calculated value of the hydrodynamic characteristics agrees well with the measured one. The pressure drop differences of the steam system between the calculated and measured values are 0.04, 0.02, 0.13, and 0.05 MPa under 100% boiler maximum continuous rating (BMCR), 75% turbine heat acceptance (THA), 50% BMCR, and 30% BMCR loads, respectively. The relative error of the mass flux distribution increases as operating load decreases, reaching a maximum (7.63%) under 30% BMCR load. For the four loads discussed in this study, the greatest temperature of the working fluid is 681.0 K, while the fin-center temperature jumps from 708.0 to 801.7 K under 100% BMCR load. The present study is intended to improve the method of the hydrodynamic performance calculation, which would benefit the safety operation of boiler during the peak-shaving process.

KEYWORDS:

• Coupled model
• combustion simulation
• hydrodynamic calculation
• mass flux
• temperature distribution

Nomenclature

$\rho$	=	working fluid density (kg m−3)
$p$	=	fluid pressure (MPa)
$g$	=	gravity acceleration (m s−2)
$E$	=	fluid total energy (J kg−1)
$v$	=	specific volume of the working fluid (m3 kg−1)
$\mathrm{R}$	=	universal gas constant (J mol−1 K−1)
$T$	=	fluid temperature (K)
$S_m$	=	mass source term (kg m−3 s−1)
$S_{\mathrm{m}\mathrm{v}}$	=	momentum source term (kg m−2 s−2)
$S_{\mathrm{h}}$	=	energy source term (W m−3)
$\mathrm{\Delta }p$	=	total pressure drop (MPa)
$\mathrm{\Delta }{p}_{\mathrm{f}}$	=	frictional resistance loss (MPa)
$\mathrm{\Delta }{p}_1$	=	local pressure drop (MPa)
$\mathrm{\Delta }{p}_{\mathrm{g}}$	=	gravity pressure drop (MPa)
$\mathrm{\Delta }{p}_{\mathrm{a}}$	=	acceleration pressure drop (MPa)
$\lambda$	=	coefficient of thermal conductivity (W m−1 K−1)
$\lambda eff$	=	effective thermal conductivity (W m−1 K−1)
$l$	=	tube length (m)
$d_{\mathrm{i}\mathrm{n}}$	=	internal diameter of tube (m)
$\omega$	=	working fluid velocity (m s−1)
${\omega }_0^{\hspace{0.17em}}$	=	circulating velocity of the working fluid (m s−1)
$\bar{x}$	=	average mass vapor rate
$\rho { }^{\mathrm{\prime }}$	=	density of saturated water (kg m−3)
$\rho { }^{\mathrm{\prime }\mathrm{\prime }}$	=	density of saturated vapor (kg m−3)
$\psi$	=	correction coefficient
$\xi$	=	local resistance coefficient for single-phase fluid
$h$	=	height difference of the target tube section (m)
$t_{\mathrm{a}}$	=	outer and inner walls’ average temperature (K)
$t_{\mathrm{p}\mathrm{j}}$	=	average temperature of the medium’s calculated part (K)
$\mu$	=	thermal shunt coefficient
$\beta$	=	ratio of tube’s inner and outer diameters
$q_{\mathrm{w},max}$	=	maximum unit heat absorption for the deviated tube (kW m−2)
${\alpha }_2$	=	exothermic coefficient from the inner wall to the working fluid (W m−2 K−1)
$\delta$	=	tube wall thickness (m)
$t_{\mathrm{o}}$	=	outer wall temperature (K)

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supporting information

Additional supporting information may be found in the online version of this article at the publisher’s web site.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15567036.2023.2282731

Additional information

Funding

This work has been financially supported by the China Power 2022 Science and Technology Project [ZGDL-KJ-2021-010].