Gas-particle flow and rapid load-up characteristics of a novel deep peak regulation burner

Abstract

Existing swirling combustion technology, which relies on faulty coal, is unable to meet deep peak shaving demands without auxiliary methods. This paper developed a deep peak regulation burner (DPRB) to achieve stable combustion at 15%–30% of the boiler’s rated load without auxiliary support. Gas-particle tests, industrial trials, and transient numerical simulations were conducted to evaluate the burner’s performance. At full rated load, the DPRB formed a central recirculation zone (RZ) with a length of 1.5d and a diameter of 0.58d (where d represents the outlet diameter). At 40%, 20%, and 15% rated loads, the RZ became annular, with diameters of 0.30d, 0.40d, and 0.39d, respectively, with a length of 1.0d. At 20% and 15% rated loads, the recirculation peak and the range of particle volume flux were comparable to those at 40% rated load. The prototype burner demonstrated that, without oil support, the gas temperature within 0 to 1.8 m from the primary air outlet remained below 609 °C, insufficient to ignite faulty coal. As the load rate increased from 20% to 30%, the prototype’s central region temperature remained low, with a maximum of 750 °C between 0 and 2.0 m. In contrast, the DPRB’s central region temperature reached 750 °C at around 0.65–0.70 m. At a 3%·min^‒1 load-up rate, when the load increased from 20% to 30%, the prototype burner extinguished after 30 s. However, the DPRB maintained stable combustion throughout the process.

Graphical abstract

Keywords

swirl burner / gas-particle flow (GPF) characteristics / numerical simulation / deep peak regulation / rapid load-up capability

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Acknowledgements

This work was supported by the Heilongjiang Touyan Innovation Team Program and the National Key Research and Development Program, China (No. 2024YFB4104803).

Competing Interests

The authors declare that they have no competing interest.

Notations

DPRB	Deep peak regulation burner
GPF	Gas-particle flow
MSCL	Minimum stable combustion load
PDA	Particle dynamic anemometer
TI	Turbulent intensity
RZ	Recirculation zone
A1	Pre-exponential factor of the primary reaction
A2	Former factor of the secondary reaction
C	Linear anisotropic scattering phase function
C1ϵ, C2ϵ	Empirical constants
C3ϵ	Empirical constants
CD	Drag coefficient
d	Inner diameter of the secondary air outlet
D	Maximum diameter of the recirculation zone
D1	Inner diameter of the primary air nozzle
Dp	Distance from the measurement point to primary air outlet
dp	Particle diameter of solid–phase
E1	Activation energy of the primary reaction
E2	Activation energy of the secondary reaction
Fr	Froude number
fw,0	Proportion of initial moisture in particles
G	Projected radiance
g	Acceleration of gravity
Gk, Gb	Turbulent kinetic energy generated by laminar velocity and buoyancy
Gθ	Rotational momentum of airflow
Gχ	Axial momentum of airflow
k	Turbulent kinetic energy
L	Length of recirculation zone
ma	Ash mass in particles
mp	Mass of coke particles
mp,0	Initial particle mass
pox	Oxygen partial pressure around the particles
Q1	Volumetric flow rate of primary airflow
qr	Radiation heat flux
R	Load rate
Rb	Radius of burner outlet
r	Length from the measuring point to the burner central axis
R1, R2	Primary and secondary reaction rates
r1	Starting position of the recirculation zone in the radial direction
r2	End position of the recirculation zone in the radial direction
Re	Reynolds number
Rt	Total reaction rate constant of coke combustion
S	Customized source terms
St	Stokes number
Sw	Swirl number
Tp	Particle temperature
U	Combined velocity value of the three-dimensional average velocity
u	Axial velocity measured by PDA
uf	Fluctuation value of axial velocity
ug, up	Gas and particle velocity
vf	Fluctuation value of radial velocity
Vp	Average velocity of primary air
w	Tangential velocity measured by PDA
wf	Fluctuation value of tangential velocity
x	Length from the measurement point to the burner outer secondary air outlet
Ym	Fluctuations from transition diffusion in compressible turbulence
α	Absorption coefficients
ρ	Air density
ρp	Solid phase density
μ	Kinematic viscosity
μg	Dynamic viscosity of gas phase
μt	Turbulent kinematic viscosity
ε	Dissipation rate of turbulent kinetic energy
σk, σε	Planck’s constant for k and ε equations
σs	Scattering coefficients

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