流化床生物质与煤掺混燃烧的全三维数值模拟研究

doi:10.11949/0438-1157.20250586

摘要/Abstract

摘要：

本文采用多相质点网格方法耦合传热、传质以及化学反应等子模型，对流化床内生物质与煤的混合燃烧过程开展了全三维数值模拟研究。通过模拟结果与实验数据进行对比，证明了所发展模型的合理性。研究了流化床内生物质与煤混合燃烧过程的气固流动、气固组分分布及颗粒温度分布等特性，并探讨了不同入口风质量流速（0.01、0.012、0.014 kg/s）和不同燃料掺混比（1∶4、3∶7、2∶3）对颗粒温度分布、传热系数以及气体产物浓度的影响。结果表明，由于颗粒尺寸/密度不同，反应器内存在明显的颗粒偏析现象，并且在密相区颗粒温度分布存在较大梯度。提高入口风质量流速显著降低了床料颗粒传热系数，缩短燃料颗粒在高温区的停留时间。入口风质量流速从0.01 kg/s增至0.014 kg/s时，出口O₂物质的量浓度升高3.7%，其余气体组分浓度降低。生物质掺混比从1∶4增至2∶3时，因生物质氢碳比高、挥发分含量高，促进H₂O和CO₂生成，出口O₂物质的量浓度降低2.1%，其余气体组分浓度上升，且生物质颗粒全床层温度升高，但对整体传热系数影响不显著。

关键词: 气固两相流, 鼓泡流化床, 生物质与煤掺混燃烧, 多相质点网格方法, 数值模拟

Abstract:

This work employs a multiphase particle grid method to couple sub-models for heat transfer, mass transfer, and chemical reactions, and conducts a full three-dimensional numerical simulation study on the mixed combustion process of biomass and coal in a fluidized bed. By comparing the simulation results with experimental data, the rationality of the developed model is verified. Subsequently, the gas-solid flow, gas-solid component distribution, and particle temperature distribution characteristics of the biomass and coal mixed combustion process in the fluidized bed were studied, and the effects of different inlet air mass flow rates (0.01, 0.012, 0.014 kg/s) and different fuel blending ratios (1∶4, 3∶7, 2∶3) on the temperature distribution of particle, particle heat transfer coefficient and gas product concentration were explored. The results show that due to differences in particle size and density, significant particle segregation occurred within the reactor, and a large gradient in particle temperature distribution was observed in the dense phase. Increasing the inlet air mass flow rate significantly reduces the bed material particle heat transfer coefficient and shortens the residence time of fuel particles in the high-temperature zone. When the inlet air mass flow rate increases from 0.01 kg/s to 0.014 kg/s, the mole concentration of O₂ at the outlet increases by 3.7%, while the concentrations of other gas components decrease. When the biomass blending ratio increases from 1∶4 to 2∶3, due to the high hydrogen-carbon ratio and high volatile content of the biomass, H₂O and CO₂ are promoted to be generated, resulting in a decrease of 2.1% in the mole concentration of O₂ at the outlet, an increase in the concentrations of other gas components, and an increase in the full bed layer temperature of the biomass particles, but the overall heat transfer coefficient is not significantly affected.

Key words: gas-solid two-phase flow, bubbling fluidized bed, biomass and coal combustion, multiphase particle-in-cell method, numerical simulation

中图分类号:

TK 121

张盼兮, 田大勇, 次东辉, 王帅, 罗坤, 樊建人. 流化床生物质与煤掺混燃烧的全三维数值模拟研究[J]. 化工学报, 2025, 76(11): 6027-6039.

Panxi ZHANG, Dayong TIAN, Donghui CI, Shuai WANG, Kun LUO, Jianren FAN. Three-dimensional numerical simulation of biomass-coal mixed combustion in fluidized beds[J]. CIESC Journal, 2025, 76(11): 6027-6039.

图/表 15

表1 燃料的工业分析及元素分析

Table 1 Proximate analysis and ultimate analysis of fuels

燃料类型	工业分析/%（质量，空气干燥基）									低位热值/（kJ/kg）
燃料类型	挥发分	固定碳	灰分	水分	碳	氢	氧	氮	硫	低位热值/（kJ/kg）
烟煤	33.23	45.50	9.27	12.00	63.51	3.90	7.47	0.98	2.87	26660
木屑	87.03	3.76	3.21	6.00	45.80	5.60	38.90	0.38	0.11	17086

表2 化学反应方程及反应速率

Table 2 Chemical reaction equations and reaction rates

方程	反应速率
$C + H 2 O ⇌ C O + H 2$	$r 1 f = 1.272 m c T s e x p - 22645 / T s [H 2 O]$
$C + H 2 O ⇌ C O + H 2$	$r 1 r = 1.044 × 10 - 4 m c T s 2 e x p - 6319 / T s - 17.29 [H 2] [C O]$
$C + C O 2 ⇌ 2 C O$	$r 2 f = 1.272 m c T s e x p - 22645 / T s [C O 2]$
$C + C O 2 ⇌ 2 C O$	$r 2 r = 1.044 × 10 - 4 m c T s 2 e x p - 2363 / T s - 20.92 [C O] 2$
$C + 2 H 2 ⇌ C H 4$	$r 3 f = 1.368 × 10 - 3 m c T s e x p - 8078 / T s - 7.087 [H 2]$
$C + 2 H 2 ⇌ C H 4$	$r 3 r = 0.151 m c T s 0.5 e x p - 13578 / T s - 0.372 [C H 4] 0.5$
$C + O 2 → C O 2$	$r 4 = 4.34 × 107 θ s T s 0.5 e x p - 13590 / T s - 0.372 [O 2]$
$C O + H 2 O ⇌ C O 2 + H 2$	$r 5 f = 7.68 × 1010 θ s T s e x p - 36640 / T g [C O] 0.5 [H 2 O]$
$C O + H 2 O ⇌ C O 2 + H 2$	$r 5 r = 6.4 × 109 T s e x p - 39260 / T g [C O 2] [H 2] 0.5$
$C O + 0.5 O 2 → C O 2$	$r 6 = 5.62 × 1012 T s e x p - 16000 / T g [C O] [O 2]$
$C H 4 + 2 O 2 → C O 2 + 2 H 2 O$	$r 7 = 3.552 × 1011 T s - 1 e x p - 1570 / T g [C H 4] [O 2]$
$H 2 + 0.5 O 2 → H 2 O$	$r 8 = 1.63 × 1011 T s - 1.5 e x p - 34300 / T g [H 2] 0.5 [O 2]$
$C 2 H 4 + O 2 → 2 C O + 2 H 2$	$r 9 = 1 × 1012 T s - 1.5 e x p - 20818.3 / T g [C 2 H 4] [O 2]$
$C H 4 + H 2 O → C O + 3 H 2$	$r 10 = 3.0 × 105 e x p - 15042 / T g [C H 4] [H 2 O]$

表2 化学反应方程及反应速率

Table 2 Chemical reaction equations and reaction rates

方程	反应速率
$C + H 2 O ⇌ C O + H 2$	$r 1 f = 1.272 m c T s e x p - 22645 / T s [H 2 O]$
$C + H 2 O ⇌ C O + H 2$	$r 1 r = 1.044 × 10 - 4 m c T s 2 e x p - 6319 / T s - 17.29 [H 2] [C O]$
$C + C O 2 ⇌ 2 C O$	$r 2 f = 1.272 m c T s e x p - 22645 / T s [C O 2]$
$C + C O 2 ⇌ 2 C O$	$r 2 r = 1.044 × 10 - 4 m c T s 2 e x p - 2363 / T s - 20.92 [C O] 2$
$C + 2 H 2 ⇌ C H 4$	$r 3 f = 1.368 × 10 - 3 m c T s e x p - 8078 / T s - 7.087 [H 2]$
$C + 2 H 2 ⇌ C H 4$	$r 3 r = 0.151 m c T s 0.5 e x p - 13578 / T s - 0.372 [C H 4] 0.5$
$C + O 2 → C O 2$	$r 4 = 4.34 × 107 θ s T s 0.5 e x p - 13590 / T s - 0.372 [O 2]$
$C O + H 2 O ⇌ C O 2 + H 2$	$r 5 f = 7.68 × 1010 θ s T s e x p - 36640 / T g [C O] 0.5 [H 2 O]$
$C O + H 2 O ⇌ C O 2 + H 2$	$r 5 r = 6.4 × 109 T s e x p - 39260 / T g [C O 2] [H 2] 0.5$
$C O + 0.5 O 2 → C O 2$	$r 6 = 5.62 × 1012 T s e x p - 16000 / T g [C O] [O 2]$
$C H 4 + 2 O 2 → C O 2 + 2 H 2 O$	$r 7 = 3.552 × 1011 T s - 1 e x p - 1570 / T g [C H 4] [O 2]$
$H 2 + 0.5 O 2 → H 2 O$	$r 8 = 1.63 × 1011 T s - 1.5 e x p - 34300 / T g [H 2] 0.5 [O 2]$
$C 2 H 4 + O 2 → 2 C O + 2 H 2$	$r 9 = 1 × 1012 T s - 1.5 e x p - 20818.3 / T g [C 2 H 4] [O 2]$
$C H 4 + H 2 O → C O + 3 H 2$	$r 10 = 3.0 × 105 e x p - 15042 / T g [C H 4] [H 2 O]$

图1 鼓泡流化床反应装置示意图：（a）几何模型及尺寸；（b）计算域网格

Fig.1 Bubbling fluidized bed reactor: (a) geometry and dimensions; (b) computational mesh

表3 鼓泡流化床生物质与煤掺混燃烧的操作参数

Table 3 Operating parameters of bubbling fluidized bed co-combustion of biomass and coal

参数	数值	单位
进料量	0.0025	kg/s
进料温度	300	K
入口风温度	643	K
辅助风速	0.05	m/s
辅助风温度	300	K

图2 不同网格下鼓泡床内的轴向变量分布：（a）压力；（b）温度

Fig.2 Axial distributions of quantities in the bed under different grid resolutions: (a) pressure; (b) temperature

图3 反应器出口气体组分：（a）质量分数随时间的变化；（b）不同统计时间段的时均摩尔分数

Fig.3 Gas species obtained at the reactor outlet: (a) time-evolution profiles of mass fraction of gas species; (b) time-averaged molar fraction of gas species in different statistical time periods

图4 出口气体摩尔分数的模拟结果和实验结果对比：（a）煤燃烧；（b）生物质燃烧

Fig.4 Comparison of gas species molar fraction between simulation results and experimental data: (a) coal combustion; (b) biomass combustion

图5 流化床内气固流型随时间的发展：(a) t = 0 s；(b) t = 0.4 s；(c) t = 1 s；(d) t = 2 s；(e) t = 5 s；(f) t = 30 s

Fig.5 Evolution of gas-solid flow patterns in the fluidized bed: (a) t = 0 s；(b) t = 0.4 s；(c) t = 1 s；(d) t = 2 s；(e) t = 5 s；(f) t = 30 s

图6 流化床颗粒组分分布：（a）颗粒组分分布云图；（b）生物质质量轴向分布；（c）煤质量轴向分布；（d）沙子质量轴向分布

Fig.6 Particle distribution in the bubbling fluidized bed: (a) snapshot of particle components; (b) axial distribution of biomass mass; (c) axial distribution of coal mass; (d) axial distribution of sand mass

图7 流化床内颗粒温度分布：（a）瞬时颗粒温度分布云图；（b）颗粒温度轴向分布

Fig.7 Temperature distribution of particles in the bubbling fluidized bed: (a) instantaneous particle temperature distribution; (b) axial distribution of particle temperature

图8 不同工况对颗粒温度分布的影响：（a）不同流速下生物质颗粒；（b）不同流速下煤颗粒；（c）不同流速下沙子颗粒；（d）不同生物质掺混比下生物质颗粒；（e）不同生物质掺混比下煤颗粒；（f）不同生物质掺混比下沙子颗粒

Fig.8 The influence of different operating conditions on the temperature distribution of particles: (a) biomass particles under different flow rates; (b) coal particles under different flow rates; (c) sand particles under different flow rates; (d) biomass particles under different biomass blending ratios; (e) coal particles under different biomass blending ratios; (f) sand particles under different biomass blending ratios

图9 不同工况对颗粒HTC轴向分布的影响：(a) 不同流速下生物质颗粒；(b) 不同流速下煤颗粒；(c) 不同流速下沙子颗粒；(d) 不同生物质掺混比下生物质颗粒；(e) 不同生物质掺混比下煤颗粒；(f) 不同生物质掺混比下沙子颗粒

Fig.9 Axial HTC distribution of particle components under different operating conditions: (a) coal particles under different inlet flow rates; (b) biomass particles under different inlet flow rates; (c) sand particles under different inlet flow rates; (d) coal particles under different biomass blending ratios; (e) biomass particles under different biomass blending ratios; (f) sand particles under different biomass blending ratios

图10 不同工况下反应器内CO2分布云图：（a）入口风质量流速为0.01 kg/s，生物质与煤的掺混比为1∶4；（b）入口风质量流速为0.012 kg/s，生物质与煤的掺混比为1∶4；（c）入口风质量流速为0.014 kg/s，生物质与煤的掺混比为1∶4；（d）入口风质量流速为0.01 kg/s，生物质与煤的掺混比为3∶7；（e）入口风质量流速为0.01 kg/s，生物质与煤的掺混比为2∶3

Fig.10 CO2 distribution in the reactor under different operating conditions: (a) inlet air mass flow rate of 0.01 kg/s, biomass and coal blending ratio of 1∶4; (b) inlet air mass flow rate of 0.012 kg/s, biomass and coal blending ratio of 1∶4; (c) inlet air mass flow rate of 0.014 kg/s, biomass and coal blending ratio of 1∶4; (d) inlet air mass flow rate of 0.01 kg/s, biomass and coal blending ratio of 3∶7; (e) inlet air mass flow rate of 0.01 kg/s, biomass and coal blending ratio of 2∶3

图11 不同工况下反应器内H2O分布云图：（a）入口风质量流速为0.01 kg/s，生物质与煤的掺混比为1∶4；（b）入口风质量流速为0.012 kg/s，生物质与煤的掺混比为1∶4；（c）入口风质量流速为0.014 kg/s，生物质与煤的掺混比为1∶4；（d）入口风质量流速为0.01 kg/s，生物质与煤的掺混比为3∶7；（e）入口风质量流速为0.01 kg/s，生物质与煤的掺混比为2∶3

Fig.11 H2O distribution in the reactor under different operating conditions: (a) inlet air mass flow rate of 0.01 kg/s, biomass and coal blending ratio of 1∶4; (b) inlet air mass flow rate of 0.012 kg/s, biomass and coal blending ratio of 1∶4; (c) inlet air mass flow rate of 0.014 kg/s, biomass and coal blending ratio of 1∶4; (d) inlet air mass flow rate of 0.01 kg/s, biomass and coal blending ratio of 3∶7; (e) inlet air mass flow rate of 0.01 kg/s, biomass and coal blending ratio of 2∶3

图12 不同工况对反应器出口气体产物生成的影响：（a）入口风质量流速；（b）生物质掺混比

Fig.12 The influence of different operating parameters on the gas products at the reactor outlet: (a) inlet air mass flow rate; (b) biomass blending ratio

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