氧热法电石生产复合移动床反应器模型化设计研究
发布时间：2018-07-13 19:52
【摘要】：传统的电热法生产电石技术存在“高污染、高排放、高能耗”等缺点,故北京化工大学刘振宇等提出了一种氧热法电石生产工艺,同时也提出了不同的反应器设计模型。本文针对年产1万吨电石的中试规模的复合床反应器开展了模型化设计研究,也即,采用散体力学方法验证并考察了两种搅拌式的复合床反应器固体布料器的流动性能,并采用计算流体力学(CFD)模拟考察了反应器密相区颗粒的热解和传热特性；同时针对反应器稀相燃烧区的设计,运用数值模拟方法考察了不同燃烧喷嘴设置下燃烧区的流动特性,据此提出喷嘴设置的优化设计方案。首先,利用离散元法研究了复合床反应器内两种不同桨叶(平桨叶和下压式桨叶)下器内颗粒流动以及布料情况。具体结论如下：(1)在两种搅拌桨叶下颗粒在床层中的速度分布基本一致,靠近搅拌桨叶的下部床层颗粒速度相对较大；上部床层由于颗粒远离桨叶,表现出明显的架桥现象,床层中颗粒速度分布不均匀；(2)平桨叶下颗粒在反应器径向上呈现“中间多,两边少”的布料分布,而下压式桨叶呈现“中间少、两边多”的布料分布;(3)在相同的转速下,采用平桨叶时颗粒在反应器径向上的分布波动比较大,而下压式桨叶布料相对均匀,从相对理想的布料形式来说,下压式桨叶是更可采取的。其次,以复合移动床反应器的移动床段为研究对象,以40mm复合颗粒为电石原料,研究了移动床段从冷态开车到热态运行所需时间及反应器热态运行时器内组分、温度等分布情况。结论如下：(1)通过模拟得到移动床从冷态运行至热态正常运行时,所需时间为1200s,即开车时间至少为1200s;(2)随着时间增加,反应器内流场、温度场、组分分布明显不同。热解初期,反应器内三场分布相对均匀；随着热解时间增加,壁面效应增强,反应器内三场分布均呈现W型分布;(3)随着床层中热解前沿的上移,反应器内可以明显的划分为热解完成区、热解区、未反应区的三段分布状态；(4)随着温度升高,复合颗粒内先后发生水分蒸发、煤热解、氢氧化钙热解,但是各物质在释放过程并没有表现出明显的界限。最后,对复合移动床反应器冷态下的流动建立数学模型,研究不同氧气喷嘴入口位置、入口角度、进气速度对反应器内流动、旋流的影响,选出了适宜的喷嘴设计参数：氧喷嘴入口位于距熔池表面的高度为0.43m、入射角度为150、进气速度为80m/s。
[Abstract]:The traditional technology of producing calcium carbide by electrothermal method has the disadvantages of "high pollution, high emission and high energy consumption". Therefore, Liu Zhenyu, Beijing University of Chemical Technology, has put forward an oxythermal calcium carbide production process and different reactor design models. In this paper, the model design of a pilot-scale composite bed reactor with an annual production of 10,000 tons of calcium carbide has been studied. In other words, the fluidity of solid distributor in two kinds of stirred bed reactors has been verified and investigated by means of bulk mechanics method. The pyrolysis and heat transfer characteristics of the dense phase particles in the reactor were investigated by computational fluid dynamics (CFD) simulation, and the flow characteristics of the combustion zone with different combustion nozzles were investigated by numerical simulation for the design of the lean phase combustion zone of the reactor. According to this, the optimal design scheme of nozzle setting is put forward. Firstly, the particle flow and distribution in two different blades (flat blade and lower pressure blade) in a composite bed reactor were studied by discrete element method. The specific conclusions are as follows: (1) the velocity distribution of particles in the bed is basically the same under the two kinds of agitating blades, the velocity of the lower bed near the agitating blade is relatively large, and the upper bed is obviously bridging because the particles are far away from the blade. The velocity distribution of particles in the bed is not uniform; (2) the distribution of particles under the flat blade is "more in the center, less in both sides" in the radial direction of the reactor, while the distribution of "less in the middle and more on both sides" in the bottom pressure blade; (3) at the same speed, The distribution of the particles in the radial direction of the reactor is more fluctuant when the flat blade is used, but the distribution of the lower pressure blade is relatively uniform, so the lower pressure blade is more suitable for the relatively ideal distribution form. Secondly, taking the moving bed section of the complex moving bed reactor as the research object and the 40mm composite particle as the raw material of calcium carbide, the time required for the moving bed section to start up from cold to hot state and the components in the reactor during the hot state operation were studied. Temperature distribution The results are as follows: (1) when the moving bed is running from cold to hot, the time required is 1200 s, that is, the start-up time is at least 1 200 s; (2) with the increase of time, the flow field, temperature field and component distribution in the reactor are obviously different. In the initial stage of pyrolysis, the distribution of the three fields in the reactor is relatively uniform; with the increase of the pyrolysis time, the wall effect increases, and the distribution of the three fields in the reactor is W-shaped; (3) with the moving up of the pyrolysis front in the bed, The reactor can be divided into three stages of pyrolysis, pyrolysis and non-reaction. (4) with the increase of temperature, water evaporation, coal pyrolysis and calcium hydroxide pyrolysis occur successively in the composite particles. However, the release of the substances did not show a clear boundary. Finally, the mathematical model of the flow in the cold state of the complex moving bed reactor is established, and the effects of the inlet position, inlet angle and inlet velocity of the oxygen nozzle on the flow and swirl in the reactor are studied. The optimum design parameters of the nozzle are as follows: the inlet height of the oxygen nozzle is 0.43m from the surface of the molten pool, the angle of incidence is 150, and the inlet velocity is 80m / s.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ161;TQ052
本文编号：2120555
[Abstract]:The traditional technology of producing calcium carbide by electrothermal method has the disadvantages of "high pollution, high emission and high energy consumption". Therefore, Liu Zhenyu, Beijing University of Chemical Technology, has put forward an oxythermal calcium carbide production process and different reactor design models. In this paper, the model design of a pilot-scale composite bed reactor with an annual production of 10,000 tons of calcium carbide has been studied. In other words, the fluidity of solid distributor in two kinds of stirred bed reactors has been verified and investigated by means of bulk mechanics method. The pyrolysis and heat transfer characteristics of the dense phase particles in the reactor were investigated by computational fluid dynamics (CFD) simulation, and the flow characteristics of the combustion zone with different combustion nozzles were investigated by numerical simulation for the design of the lean phase combustion zone of the reactor. According to this, the optimal design scheme of nozzle setting is put forward. Firstly, the particle flow and distribution in two different blades (flat blade and lower pressure blade) in a composite bed reactor were studied by discrete element method. The specific conclusions are as follows: (1) the velocity distribution of particles in the bed is basically the same under the two kinds of agitating blades, the velocity of the lower bed near the agitating blade is relatively large, and the upper bed is obviously bridging because the particles are far away from the blade. The velocity distribution of particles in the bed is not uniform; (2) the distribution of particles under the flat blade is "more in the center, less in both sides" in the radial direction of the reactor, while the distribution of "less in the middle and more on both sides" in the bottom pressure blade; (3) at the same speed, The distribution of the particles in the radial direction of the reactor is more fluctuant when the flat blade is used, but the distribution of the lower pressure blade is relatively uniform, so the lower pressure blade is more suitable for the relatively ideal distribution form. Secondly, taking the moving bed section of the complex moving bed reactor as the research object and the 40mm composite particle as the raw material of calcium carbide, the time required for the moving bed section to start up from cold to hot state and the components in the reactor during the hot state operation were studied. Temperature distribution The results are as follows: (1) when the moving bed is running from cold to hot, the time required is 1200 s, that is, the start-up time is at least 1 200 s; (2) with the increase of time, the flow field, temperature field and component distribution in the reactor are obviously different. In the initial stage of pyrolysis, the distribution of the three fields in the reactor is relatively uniform; with the increase of the pyrolysis time, the wall effect increases, and the distribution of the three fields in the reactor is W-shaped; (3) with the moving up of the pyrolysis front in the bed, The reactor can be divided into three stages of pyrolysis, pyrolysis and non-reaction. (4) with the increase of temperature, water evaporation, coal pyrolysis and calcium hydroxide pyrolysis occur successively in the composite particles. However, the release of the substances did not show a clear boundary. Finally, the mathematical model of the flow in the cold state of the complex moving bed reactor is established, and the effects of the inlet position, inlet angle and inlet velocity of the oxygen nozzle on the flow and swirl in the reactor are studied. The optimum design parameters of the nozzle are as follows: the inlet height of the oxygen nozzle is 0.43m from the surface of the molten pool, the angle of incidence is 150, and the inlet velocity is 80m / s.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ161;TQ052
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