电石炉净化灰回收利用工艺技术研究

发布时间：2018-04-08 21:56

本文选题：密闭电石炉　切入点：净化灰　出处：《北京化工大学》2015年硕士论文

【摘要】：密闭电石炉产生的尾气含有50-150g/Nm~3的粉尘,一般需通过净化装置进行处理方可回收利用。净化处理时尾气首先进入沉降器将40%-50%的大颗粒粉尘沉降下来,然后经空冷器进行降温除尘,再进入布袋除尘器进行精过滤,经沉降器、空冷器及布袋除尘器收集的固体粉尘一般称之为净化除尘灰(简称净化灰)。目前主要的处理方式为填埋,而灰分中含有较高的氧化钙、氧化镁、碱类和氰等,会造成严重的环境污染和资源浪费。因此,对净化灰回收利用工艺技术进行改进,具有较大的环保、经济和社会效益。本文首先深入分析了净化灰产生机理和理化性质,选择制定出利用净化灰替代兰炭粉末进行焚烧的回收利用方案,通过对净化灰收集系统、管道输送系统、终端存储系统、焚烧系统、灰渣回收系统等五大系统的原有设计工艺存在的缺陷进行研究分析和优化设计,在生产实践中取得了较好的成效。主要工作如下：1、净化灰理化性质分析表明,净化灰钙、镁含量较高,含水量低,与兰炭末相比几乎可以忽略,挥发分约为兰炭末的6倍,含碳量约为兰炭末的二分之一,发热量不到兰炭末的三分之一。2、原有净化灰存储仓采用人工控制卸灰阀放灰,改进后,存储仓与氮气罐连接,保证足够的氮气浓度,防止净化灰自燃,且系统自动启动储灰仓输送程序输送,输送完毕后再次卸灰,如此间歇输送。3、原输送工艺使用自卸车接灰,费用高且存在环境污染和安全风险。改进后,采用气力输送技术,实现封闭式输送,确保安全输送,降低净化灰卸灰、输送时对环境造成的污染。4、由管道输送过来的净化灰集中储存在锥形储灰罐中。原储存系统未通入氮气保护,易发生自燃,未加装流化板,下灰不畅易堵塞管道,给检修工作带来很大的困难。改进后,解决了净化灰粘壁、下灰不畅、堵塞管道、灰量难控制及存在粉尘爆炸风险等诸多问题。5、使用纯兰炭粉时沸腾炉风管压力较高,使用净化灰时,沸腾炉风管压力下降。因此,使用净化灰代替兰炭,适当降低沸腾炉风管压力,且效果较好。6、对灰渣回收系统进行优化设计,即在灰渣仓顶部加装旋风除尘器,大颗粒灰渣经旋风沉降后直接进入灰渣仓,灰渣中少量细渣和灰分经负压管道吸至布袋除尘器内。该工艺效果较好,布袋未出现烧损问题,延长了布袋更换周期,同时降低了检修工作量。
[Abstract]:The tail gas produced by closed calcium carbide furnace contains 50-150g/Nm~3 dust.In the process of purification and treatment, the tail gas first enters the precipitator and settles 40% to 50% of the large particle dust, then it is cooled and dusted by an air cooler, and then it enters the bag dust collector for fine filtration, and then it passes through the settler.The solid dust collected by air cooler and bag precipitator is generally called purifying dust.At present, the main treatment is landfill, and ash contains high calcium oxide, magnesium oxide, alkalinity and cyanide, which will cause serious environmental pollution and waste of resources.Therefore, it has great environmental, economic and social benefits to improve the recovery and utilization technology of purified ash.In this paper, the mechanism and physical and chemical properties of purifying ash are analyzed in depth, and the recovery and utilization scheme of incineration using purified ash instead of blue charcoal powder is selected. The collection system, pipeline transportation system and terminal storage system of purifying ash are analyzed through the analysis of purification ash collection system, pipeline transportation system and terminal storage system.The defects in the original design process of the five systems, such as incineration system and ash and slag recovery system, were studied and optimized, and good results were obtained in production practice.The main work is as follows: 1. The physicochemical properties of purified ash show that the content of calcium and magnesium in purified ash is high, the water content is low, and the volatile content is about 6 times as much as that of blue charcoal, and the carbon content is about 1/2 of that of blue charcoal.The calorific value is less than 1/3. 2 of the blue charcoal powder. The original cleaning ash storage bin uses manual control ash unloading valve to release ash. After improvement, the storage bin is connected with the nitrogen tank to ensure sufficient nitrogen concentration to prevent the purification ash from spontaneous combustion.The system automatically starts the conveying process of ash storage bin and unloads the ash again after the transportation is finished. The original conveying process uses the dump truck to connect the ash with high cost and environmental pollution and safety risk.After improvement, the pneumatic conveying technology is adopted to realize the closed conveying, to ensure the safe transportation, to reduce the pollution caused by the clean ash unloading, to pollute the environment when conveying, and to store the purified ash from the pipeline in the conical ash storage tank.Since the original storage system is not protected by nitrogen gas, it is easy to occur spontaneous combustion, no fluidized plate is installed, and the ash is not smooth and easy to block the pipeline, which brings great difficulties to the maintenance work.After improvement, many problems such as sticking to the wall of purifying ash, impairing the lower ash, blocking the pipe, controlling the ash quantity and the risk of dust explosion are solved. 5. The pressure of the blast tube of the fluidized bed furnace is higher when using pure blue charcoal powder, and the pressure of the blast tube of the fluidized bed furnace decreases with the use of the purified ash.Therefore, using purifying ash instead of orchid charcoal, properly reducing the pressure of fluidized bed furnace blast tube, and the effect is better. 6. The optimum design of ash recovery system is carried out, that is, adding cyclone dust collector to the top of ash bin,The large particle ash directly enters the ash bin after the whirlwind settling, and a small amount of fine slag and ash in the ash is absorbed into the bag dust collector by negative pressure pipeline.The effect of this process is good, the bag does not appear burning problem, prolongs the replacement period of cloth bag, and reduces the overhauling work at the same time.
【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

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