Particle velocity and concentration distribution in double-exit staged entrained-flow gasifier

doi:10.11949/0438-1157.20220608

Abstract

Abstract:

Staged utilization of coal is one of the main ways of efficient and low-carbon utilization of coal, a new type of staged entrained-flow gasifier is investigated for production of pyrolysis gas and synthesis gas, the upper part of the gasifier is a coal pyrolysis chamber and the lower part is a coal coke gasification chamber. In order to reveal the characteristics of the gas-solid flow in the gasifier, PV6M particle velocimeter was used to measure the velocity and concentration distribution of solid particles in the gasifier, and the gas-solid flow field in the gasifier was simulated with CFD software. The results indicated that the particle velocity was higher in the jet development region and the refraction flow development region after jet collision. The particle velocity in the side area was lower and the phenomenon of backflow appeared. Under the effect of inertia and airflow traction, most of the particles in the pyrolysis chamber flowed into the gasification chamber. The radial particle concentration centering in the upper part of the pyrolysis chamber was higher than the side wall. The radial particle concentration centering in the lower part of the gasification chamber was higher in the side area. The pyrolysis chamber to gasification chamber inlet air ratio, nozzle angle and particle diameter had an important influence on the particle outflow distribution at the gasifier outlet. The deflection angle of the pyrolysis nozzle and the Stokes number of the particles increased, and the proportion of the particles flowing out from the outlet of the pyrolysis chamber decreased.

Key words: staged gasification, pyrolysis, gas-solid two-phase flow, numerical simulation

摘要：

煤炭分级利用是煤炭高效低碳利用的主要途径之一，提出一种同时制备热解气和合成气的分级气流床气化炉，炉体上部为煤热解室，下部为煤焦气化室。采用PV6M颗粒测速仪对气化炉内固体颗粒的速度和浓度分布进行测量，并运用CFD软件对气化炉内气固两相流场进行模拟。结果表明，在射流发展区域与射流碰撞后的折射流发展区域，颗粒速度较高；边壁区域颗粒速度较低且出现回流现象。在惯性和气流曳力作用下，热解室内大部分颗粒自流进入气化室。热解室上部径向颗粒浓度中心高边壁低；气化室下部径向颗粒浓度中心低边壁高。热解室与气化室进气量比、喷嘴角度及颗粒直径等对气化炉出口颗粒流出量分配有重要的影响。热解室进气量增大，颗粒从热解室出口流出占比先减小后增大；热解喷嘴偏转角与颗粒Stokes数增大，颗粒从热解室出口流出占比减小。

关键词: 分级气化, 热解, 气固两相流, 数值模拟

CLC Number:

O 359⁺.2

Huaxing ZHU, Jingxiao WANG, Jianliang XU, Zhenghua DAI, Haifeng LIU. Particle velocity and concentration distribution in double-exit staged entrained-flow gasifier[J]. CIESC Journal, 2022, 73(10): 4355-4365.

朱华兴, 王景效, 许建良, 代正华, 刘海峰. 双出口分级气流床气化炉内颗粒速度和浓度分布[J]. 化工学报, 2022, 73(10): 4355-4365.

Figures/Tables 17

Fig.1 Schematic diagram of gasifier structure

Fig.2 Experiment process1—blower; 2—valve; 3—rotameter; 4—silos; 5—feeder; 6—P-nozzle; 7—G-nozzle; 8—P-exit; 9—G-exit; 10—gasifier; 11—probe; 12—PV6M particle velocimeter; 13—computer

Fig.3 Grid independence verification

Fig.4 Simulation grid profile of gasifier

Table 1 Experimental conditions

热解喷嘴下偏转角γ/(°)

热解喷嘴左偏转角θ/(°)

颗粒流量/

(kg/h)

总进气量/

(m³/h)

热解室进气量/

(m³/h)

气化室进气量/

(m³/h)

Fig.5 Particle velocity, concentration distribution at inlet air ratio α=1∶4

Fig.6 Axial particle velocity distribution in the gasifier

Fig.7 Particle velocity distribution along the pyrolysis chamber nozzle axis

Fig.8 Radial particle velocity distribution in different planes in the gasifier

Fig.9 Axial particle concentration distribution in the gasifier

Fig.10 Radial particle concentration distribution in different planes in the gasifier

Fig.11 Particle concentration distribution on the inner wall of the gasifier

Fig.12 Particle outflow distribution in different exits at different inlet air ratio

Table 2 Simulated conditions

进气量比α	下偏转角γ/(°)	左偏转角θ/(°)
1∶4	10.0	0
	12.5	0
	15.0	0
	17.5	0
	20.0	0
	15.0	3
	15.0	6
	15.0	9
	15.0	12

Fig.13 Particle outflow distribution in different exits at different pyrolysis chamber nozzle angles

Fig.14 Particle outflow distribution in different exits at different mean particle diameter

Fig.15 Particle outflow distribution in different exits at different Stokes number

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