INFLUENCE OF THE MODEL SCALE ON HYDRODYNAMIC SCALING IN CFB BOILERS

Mirek, P.

doi:10.1590/0104-6632.20160334s20150348

P. Mirek ^**To whom correspondence should be addressed

Institute of Advanced Energy Technologies, Czestochowa University of Technology Dąbrowskiego 69, 42-201 Częstochowa, Poland. Phone: + 48 34 3250 933; Fax: + 48 34 3250 933. E-mail: pmirek@neo.pl

*To whom correspondence should be addressed

Thumbnail

Figure 1
Schematicdiagram of the Lagisza 966 MW_th supercritical CFB boiler.

Thumbnail

Figure 2
Cross-sectionsof the Lagisza 966 MW_th supercritical CFB boiler (27.6×10.6 m²) and 1/20 (0.69×0.53 m²; 1/2 of the Lagisza CFB boiler cross-section) and 1/10 (0.69×0.53 m²; 1/8 of the Lagisza CFB boiler cross-section) scale cold models.

Thumbnail

Figure 3
Massflow of solids measured in downcomers DC1, DC2, DC3 and DC4 of the 1/20 cold model.

Thumbnail

Figure 4
Externalsolids circulation flux for different loads of the Lagisza 966 MW_th CFB boiler estimated based on tests carried-out on the 1/20 scaled-down model.

Thumbnail

Figure 5
Thescaled-down models of the Lagisza 966 MW_th supercritical CFB boiler.

Thumbnail

Figure 6
PSDsof the inert material circulating in the Lagisza 966 MW_th CFB boiler and the scaling models calculated from the set of Eq. (7).

Thumbnail

Figure 7
Suspensiondensity distributions for the Lagisza 966 MW_th CFB boiler and 1/10 and 1/20the scale cold models at 100% MCR.

Thumbnail

Figure 8
Suspensiondensity distributions for the Lagisza 966 MW_th CFB boiler and the 1/10 and 1/20 scale cold models at 80% MCR.

Thumbnail

Figure 9
Suspensiondensity distributions for the Lagisza 966 MW_th CFB boiler and the 1/10 and 1/20 scale cold models at 60% MCR.

Thumbnail

Figure 10
Suspensiondensity distributions for the Lagisza 966 MW_th CFB boiler and the 1/10 and 1/20scale cold models at 40% MCR.

Thumbnail

Table 1
Particulate materials and scale factors used in scaling experiments.

Thumbnail

Table 2
Proximate and ultimate analyses of bituminous coal.

Thumbnail

Table 3
Parameters of the Lagisza 966 MW_th CFB boiler and small-scale equivalents according to the set of simplified scaling laws Eq. (7)

Thumbnail

A cross-sectional area (m2) Ar Archimedes number dp3ρf (ρp-ρf)g/μ2 (-) Cd drag coefficient (-) dp particle diameter (m) d* dimensionless particle diameter (-) d32 Sauter mean particle diameter (m) d50 mass mean particle diameter (m) D riser hydraulic mean diameter 4A/P (m) g acceleration of gravity (m/s2) h height (m) H combustion chamber height (m) Hb boiler's combustion chamber height (m) Hm cold model's combustion chamber height (m) FrH Froude number based on H U02/gH) (-) Ġs external solids circulation flux (kg/m2s) kx, ky, kz scale factor in x, y and z directions (-) L width of the core region along the line of measurements (m) L1,L2 cross-sectional bed dimensions (m) MCR Maximum Continuous Rating (%) ṁb mass flow of solids in the boiler (kg/s) ṁm mass flow of solids in the cold model (kg/s) U 0 superficial gas velocity (m/s) U0b superficial gas velocity in the boiler (m/s) U0m superficial gas velocity in the cold model (m/s) U* dimensionless velocity, (4Red/(3Cd))1/3 (-) umf minimum fluidization velocity (m/s) ut terminal velocity of particle (m/s) p pressure (Pa) P wetted perimeter of the cross-section (m) PSD particle size distribution PA/SA primary/secondary air ratio (-) ReH Reynolds number based on the riser height H (-) Rep particle Reynolds number (-) T temperature (K) x coordinate of the combustion chamber height (m) Greek Letters ρb solids suspension density (kg/m3) ρf gas density (kg/m3) ρp particle density (kg/m3) φ particle sphericity (-) μ gas viscosity (Pa s) ε static porosity (-)

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

(11)

	Scaled model			References
	ρ_p, kg/m³	d_p, mm	Scale factor	References
Plastic	1410	144.5; 99.5	0.25; 0.0625	*Glicksman et al. (1993)*Glicksman, L. R., Hyre, M. R., Westphalen, D., Verification of scaling relations for circulating fluidized beds. Proc. of 12th Int. Conf. on Fluidized Bed Combustion, 69-80 (1993).
Plastic	1440	136	-	Bricout and Louge (2004)Bricout, V., Louge, M. Y., A verification of Glicksman's reduced scaling under conditions analogous to pressurized circulating fluidization. Chemical Engineering Science, 59, 2633-2638 (2004).
FCC	1500	67	-	*Qi et al. (2008)*Qi, X., Zhu, J., Huang, W., Hydrodynamic similarity in circulating fluidized bed risers. Chemical Engineering and Science, 63, 5613-5625 (2008).
FCC Catalyst	1780	46.4	0.25	Horio (1996)Horio, M., Hydrodynamics. Chapter 2, In: Circulating Fluidized Beds, Edited by Grace, J. R., Knowlton, T. M., Avidan, A. A, Blackie Academic and Professional (1996).
Sand	2368	125	0.17	Kolar and Leckner (2006)Kolar, A. K., Leckner, B., Scaling of CFB boiler hydrodynamics. Proc. of the 1st National Conference on Advances in Energy Research (AER 2006), Mumbai, 34-40 (2006).
Sand	2710	461	-	*Qi et al. (2008)*Qi, X., Zhu, J., Huang, W., Hydrodynamic similarity in circulating fluidized bed risers. Chemical Engineering and Science, 63, 5613-5625 (2008).
Glass beads	2500	71.4	0.05	Mirek (2011)Mirek, P., Ziaja, J., The influence of sampling point on solids suspension density applied in scaling of the hydrodynamics of a supercritical CFB boiler. Chemical and Process Engineering, 32(4), 391-399 (2011).
	2530	97	-	Bricout and Louge (2004)Bricout, V., Louge, M. Y., A verification of Glicksman's reduced scaling under conditions analogous to pressurized circulating fluidization. Chemical Engineering Science, 59, 2633-2638 (2004).
	2558	81.6; 88.3; 112.3; 78.7	0.25; 0.0625	*Glicksman et al. (1993)*Glicksman, L. R., Hyre, M., Woloshum, K., Simplified scaling relationships for fluidized beds. Powder Technology, 77, 177-199 (1993).
Iron	7860	56	0.11	*Leckner et al. (2011)*Leckner, B., Szentannai, P., Winter, F., Scale-up of fluidized-bed combustion-A review. Fuel, 90, 2951-2964 (2011).
Steel	8027	46	0.11	*Leckner et al. (2011)*Leckner, B., Szentannai, P., Winter, F., Scale-up of fluidized-bed combustion-A review. Fuel, 90, 2951-2964 (2011).
	8097	200	0.25	*Glicksman et al. (1987)*Glicksman, L. R., Yule, T., Dyrness, A., Carson, R., Scaling the hydrodynamics of fluidized bed combustors with cold models: Experimental confirmation. Proc. of 9th Int. Conf. on Fluidized Bed Combustors, 511-514 (1987).
	7300	58; 49.5	0.25; 0.0625	*Glicksman et al. (1993)*Glicksman, L. R., Hyre, M., Woloshum, K., Simplified scaling relationships for fluidized beds. Powder Technology, 77, 177-199 (1993).
Bronze	8563	73.4; 69.5	0.17	Kolar and Leckner (2006)Kolar, A. K., Leckner, B., Scaling of CFB boiler hydrodynamics. Proc. of the 1st National Conference on Advances in Energy Research (AER 2006), Mumbai, 34-40 (2006).
Bronze	8800	60	0.11	*Sterneus et al. (2002)*Sterneus, J., Johnsson, F., Leckner, B., Characteristics of gas mixing in a circulating fluidised bed. Powder Technology, 126, 28-41 (2002).

Proximate analysis (as-received)			Ultimate analysis (air dried basis)
Component	Unit	Overall range	Component	Unit	Overall range
C	wt, %	54.3-58.7	LHV	MJ/kg	21.35-23.48
S^combustible	wt, %	0.95-1.25	Moisture	wt, %	12.20-18.45
H	wt, %	3.93-4.15	Volatile matter	wt, %	26.55-29.72
N	wt, %	0.85-0.91	Ash	wt, %	10.42-18.17
O^bydifference	wt, %	7.82-8.81

		Lagisza SC-CFB				1/20 cold model				1/10 cold model
MCR	⋅	100	80	60	40	100	80	60	40	100	80	60	40
U ₀	m/s	5.10	4.17	3.14	2.62	1.49	1.22	0.92	0.76	1.49	1.22	0.92	0.76
PA/SA	-	1.86	2.33	3.00	5.25	1.86	2.33	3.00	5.25	1.86	2.33	3.00	5.25
d ₃₂	m	122.99⋅10^-6				44.05⋅10^-6				44.05⋅10^-6
d ₅₀	m	234.57⋅10^-6				84.01⋅10^-6				84.01⋅10^-6
**ρ_p/ρ_f**	-	8724				2076				2076
µ	Pa s	4.456⋅10^-5				1.813⋅10^-5				1.813⋅10^-5
T	K	1123				293				293
D	m	15.32				0.6				0.6
*u_t*	m/s	0.479				0.139				0.139
*u_mf*	m/s	0.00639				0.00187				0.00187
*Re_d*	-	4.357	3.563	2.683	2.238	4.357	3.563	2.683	2.238	4.357	3.563	2.683	2.238
Ar	-	7.68				7.68				7.68

A	cross-sectional area (m²)
Ar	Archimedes number d_p³ρ_f (ρ_p-ρ_f)g/μ² (-)
C_d	drag coefficient (-)
d_p	particle diameter (m)
d_*	dimensionless particle diameter (-)
d₃₂	Sauter mean particle diameter (m)
d₅₀	mass mean particle diameter (m)
D	riser hydraulic mean diameter 4A/P (m)
g	acceleration of gravity (m/s²)
h	height (m)
H	combustion chamber height (m)
H_b	boiler's combustion chamber height (m)
H_m	cold model's combustion chamber height (m)
Fr_H	Froude number based on H U₀²/gH) (-)
Ġ_s external solids circulation flux (kg/m²s)
k_x, k_y, k_z	scale factor in x, y and z directions (-)
L	width of the core region along the line of measurements (m)
L₁,L₂	cross-sectional bed dimensions (m)
MCR	Maximum Continuous Rating (%)
ṁ_b	mass flow of solids in the boiler (kg/s)
ṁ_m	mass flow of solids in the cold model (kg/s)
U ₀	superficial gas velocity (m/s)
U_0b	superficial gas velocity in the boiler (m/s)
U_0m	superficial gas velocity in the cold model (m/s)
U*	dimensionless velocity, (4Re_d/(3C_d))^1/3 (-)
u_mf	minimum fluidization velocity (m/s)
u_t	terminal velocity of particle (m/s)
p	pressure (Pa)
P	wetted perimeter of the cross-section (m)
PSD	particle size distribution
PA/SA	primary/secondary air ratio (-)
Re_H	Reynolds number based on the riser height H (-)
Re_p	particle Reynolds number (-)
T	temperature (K)
x	coordinate of the combustion chamber height (m)
Greek Letters
ρ_b	solids suspension density (kg/m³)
ρ_f	gas density (kg/m³)
ρ_p	particle density (kg/m³)
φ	particle sphericity (-)
μ	gas viscosity (Pa s)
ε	static porosity (-)

[1] *To whom correspondence should be addressed

Brasil

Brasil

INFLUENCE OF THE MODEL SCALE ON HYDRODYNAMIC SCALING IN CFB BOILERS

Abstract