氯化镁中试热解炉热工过程数值计算研究

doi:10.19964/j.issn.1006-4990.2023-0166

Abstract

Abstract:

In order to explore the complex thermal process in the pyrolysis furnace，the core equipment of MgCl₂ spray pyrolysis process，and improve the quality of process products and equipment service life，Euler-Lagrange method was used to establish a mathematical model of gas-particle two-phase flow heat transfer coupled with pyrolysis reaction.The temperature field，particle decomposition process and HCl distribution during the stable operation of pyrolysis furnace were studied.And the influence of gas inlet temperature and flow rate on MgO conversion and HCl distribution was explored.The results showed that the product conversion rate was gradually increased with the increase of flue gas inlet temperature and inlet flow in the scope of the study.When the flue gas inlet was kept at 1.5 m³/s， the product conversion rate reaches 100% at the inlet temperature of 1 423 K. When the flue gas inlet temperature was kept at 1 273 K， the product conversion rate reaches 100% at the inlet flow rate of 2.25 m³/s.As the particles moving downward，the HCl concentration was radually increased and reached a maximum concentration of 6.5% at the discharge port.Moreover，with the increase of flue gas inlet temperature and inlet flow，the HCl concentration at the discharge port showed a change law of firstly increasing and then decreasing.The flue gas inlet temperature and inlet flow rate corresponding to the maximum value were 1 373 K and 1.75 m³/s，respectively.

Key words: MgCl₂, pyrolysis, Euler-Lagrange method, CFD, numerical simulation

CLC Number:

TQ132.2

WANG Jinji, ZHAO Liang, ZHANG Menghui, XU Hanlu, DONG Hui. Numerical simulation of thermal characteristics in magnesium chloride pilot pyrolysis furnace[J]. Inorganic Chemicals Industry, 2023, 55(12): 140-145.

Figures/Tables 12

Fig.1

Table 1

Kinetic parameters of MgCl2·6H2Othermal decomposition"

编号	方程式	指前因子 A_m/s^-1	活化能E/（kJ‧mol^-1）
1	$M g C l 2 ⋅ 6 H 2 O → M g C l 2 ⋅ 4 H 2 O + 2 H 2 O$	3.6×10⁹	66.8
2	$M g C l 2 ⋅ 4 H 2 O → M g C l 2 ⋅ 2 H 2 O + 2 H 2 O$	8.8×10¹⁷	138.0
3	$M g C l 2 ⋅ 2 H 2 O → M g C l 2 ⋅ H 2 O + H 2 O$	4.6×10⁹	77.2
4	$M g C l 2 ⋅ H 2 O → M g O H C l + H C l$	78.6	135.6
5	$M g O H C l → M g O + H C l$	1.2×10³	92.2

Table 1

Table 2

Table 3

Table 4

Fig.2

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边界	边界类型	DPM设置	热边界类型
烟气入口	Velocity inlet	Escape
烟气出口	Pressure outlet	Escape
排料口	Wall	Escape	绝热
其余炉壁	Wall	Reflect	绝热

入口温度/K	气体出口温度及误差			产品转化率/%
入口温度/K	实验值/K	模拟值/K	误差/%	实验值	模拟值	误差
1 223	890.83	906.96	-1.78	74.50	77.90	-4.36
1 273	897.50	937.54	-4.27	89.14	87.97	1.33
1 323	998.64	967.60	3.21	90.69	94.25	-3.78
1 373	1 020.10	1 002.12	1.79	99.38	97.58	1.84

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Numerical simulation of thermal characteristics in magnesium chloride pilot pyrolysis furnace

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