12500kVA硅铁电炉除尘及投资效益.pdf

12 500 kVA 硅铁电炉除尘及投资效益 刘 圣 攀枝花攀钢集团设计研究院有限公司, 四川 617023 摘要 介绍了 12 500 kVA 硅铁电炉除尘工艺、主要设备组成及除尘系统优势, 并对硅微粉的回收进行了投资分析。 关键词 硅铁电炉 除尘 硅粉回收 效益 1 前言 德昌铁合金集团原有铁合金 含硅铁、 硅锰 生产 车间 2 个, 年产硅铁约10 000 t 。为了扩大硅铁生产 规模, 德铁集团与西昌电力公司合资, 新建 2 台 12 500 kVA硅铁电炉 。电炉只配套设置了半封闭型 电炉矮烟罩 ,生产时产生大量的烟气, 为此新建了电 炉烟气除尘系统 。由于烟尘中 SiO2含量较高, 粒度 极小 ,称为硅微粉,可以作为再利用的一种资源。 2 除尘方式及滤料 电炉基础参数为 烟气量 70 000 Nm 3 h座; 烟气温度 450 ℃; 烟气含尘浓度 3～ 4 g Nm 3 ; 烟气成分 CO23; N275～ 78; O218 ; 烟尘 粒 度 1 μ m 88; 1 ～ 10 μ m 5; 10～ 40 μ m 7; 烟尘成分 SiO290; FeO 0. 5～ 3; MgO 1; Al2O30. 2～ 1. 5; CaO 0. 4～ 1; C 3～ 4 目前, 铁合金厂硅铁电炉除尘, 干法除尘一般是 采用辐射 U 型管空冷器冷却烟气 , 采用大气反吹风 大布袋除尘器除尘的方式净化烟气。净化系统一般 为负压式除尘系统。这种除尘系统虽然效果不错 ,但 一次性投资较高 。综合考虑, 除尘系统设计采用正压 式布袋除尘系统 ,且采用列管式空冷器冷却烟气。 由于烟尘粒径很小, 绝大部分为1 μ m以下, 用普 通滤 料 如 802、729 过 滤, 过 滤 风 速 一 般 较 低 0. 5 m min , 因此, 存在除尘器的过滤面积很大, 检修 、 换袋工作量大 ,除尘器过于庞大、除尘器投资高 等问题。 该除尘器采用覆膜滤料, 这种滤料制成的滤袋过 滤表面复合一层极薄的微孔聚四氟乙烯材料 ,由于聚 四氟乙烯固有的化学和物理特性 , 表面极为光滑, 粉 尘不易粘结在滤袋上 ,较低的清灰能耗就可以把粉尘 清落下来, 提高了滤袋的清灰再生功能和清灰效果, 因此过滤风速可以大大提高。 3 除尘工艺 电炉烟气经列管式空冷器间接冷却后,烟气温度 由450 ℃降至240 ℃,然后直接混入冷空气 ,将烟气温 度降为 180 ℃,经风机送入正压式布袋除尘器净化处 理,达到国家规定的排放标准后直接排放 。工艺流程 见附图。 附图 12 500 kVA 硅铁电炉除尘工艺流程图 112 500 kVA 硅铁电炉; 2出铁口排烟罩; 3矮烟罩; 4出铁口 排烟切换阀; 5放散烟囱; 6烟囱放散阀; 7出铁口排烟风机; 8空气冷却器; 9预收尘器; 10混风阀; 11主引风机; 12正 压式布袋除尘器; 13刮板输送机; 14粉尘包装袋。 当电炉烟气异常或除尘系统出现故障、检修时, 切断除尘系统, 打开烟囱放散阀, 烟气通过烟囱短时 间事故排放 ,不影响电炉正常生产。 对进入除尘器前的烟气温度进行随时检测,当烟 气温度超过设定值时 ,打开混风阀, 混入冷风 ,降低温 度,保护除尘器滤袋 。 采用 PLC 对所有除尘设备实现全自动逻辑控 制,确保系统运行安全、 可靠。 为了回收硅微粉 ,除尘系统中采用了硅微粉预收 尘器 ,确保硅微粉中 SiO2含量达到或超过 90。 38 环 境 工 程 2005年 2 月第23 卷第1 期 4 除尘系统参数计算 4. 1 系统风量 烟气经空冷器间接冷却至240 ℃后, 直接混冷风 30 ℃ ,降至 180 ℃,其最大冷空气量可按下列热平 衡方程式计算 Lp 22. 4[ Cpptp-Cpctc] La 22. 4[ Cpactc-Cpata] 1 式中 Lp 需冷却的高温烟气量 70 000 Nm 3 h; Cpp 从0～ tp℃ 烟气的平均比热kJ kmol℃; 查钢铁企业采暖通风设计手册中表 6-2得 29. 55; Cpc 从 0～ tc℃ 烟气的平均比热kJ kmol℃, 取 29. 47; tp 高温烟气初温 240 ℃; tc 和冷空气混合后的烟气温度 180 ℃; La 吸入的冷空气量 Nm 3 h; ta 吸入的冷空气温度 30 ℃; Cpac 从 0～ tc℃ 烟气的平均比热kJ kmol℃; 取 29. 15。 Cpa 从 0～ ta℃ 烟气的平均比热kJ kmol℃; 取 29. 09。 计算得 La 2. 86 万 Nm 3 h 系统总风量 72. 86 9. 86 万 Nm 3 h 15. 25 万 m 3 h 4. 2 系统阻力 设备阻力 ■Pm ■P1■P2■P3 2 式中 ■Pm 设备总阻力 Pa; ■P1 除尘器阻力 2 000 Pa; ■P2 空冷器阻力 1 700 Pa; ■P3 预收尘器阻力 900 Pa 。 通过计算得 ■Pm 4 600 Pa 管路阻力 P RmL 1 2 ξ V 2 ρ 3 式中 P 管路总阻力 Pa ; Rm 直管段单位摩擦阻力 Pa m ,查钢铁企 业采暖通风设计手册中表 10 - 12得 1. 56; L 风管总长度 140 m ; ξ 局部阻力系数 ; 查钢铁企业采暖通风 设计手册中表 10- 14 得 2. 42; V 管道风速 20 m s; ρ 烟气密度 1. 3 kg m 3 。 通过计算得 P 850 Pa 系统总阻力 ■P ■PmP 4 600 850 5 450 Pa 4 考虑德昌海拔修正, 系统全压为 5 450 0. 1 0. 088 6 190 Pa 综合 计 算 , 除 尘 系 统 主 风 机 的 工 况 点 为 152 400 m 3 h,工况温度 180 ℃, 全压 6 190 Pa。 4. 3 空冷器冷却面积 间接空冷是利用高温烟气在管内流通,室外常温 空气在管外流过 ,将烟气的热量带走, 使烟气温度降 低的一种冷却方式。该装置构造较为简单, 易维护, 不增加烟气体积 ,具有节能效果。 自然对流空冷器进口温度为 450 ℃ 刺火时最大 为500 ℃ , 冷却后烟气温度降为 240 ℃,自然对流空 冷器的冷却面积 ,可按下式计算 F Q K ■tm 5 式中 Q 烟气在空冷器内放出的最大热量 考虑 电炉刺火时 kJ h 。根据 1 可以计算 出 Q 3. 24 10 7 ; K 传热系数 kJ m 2h℃取 80; ■tm 高 温 烟 气 与 空 气 的 平 均 温 差 290 ℃。 通过计算得 F 1 400 m 2 ,根据全国同类型的硅 铁电炉除尘系统的空冷器的实际使用情况,取空冷器 的冷却面积为 1 500 m 2 ,并通过连通阀使冷却面积可 调,以适应不同的电炉工况。 5 除尘系统的特点 1 以正压式除尘系统与负压式除尘系统比较, 正压式除尘系统布置更加紧凑 ,而且没有了大烟囱及 大的烟气管路, 投资大为减少 680 万元 。负压式除 尘系统占地面积较大 64 m 24 m ,正压式占地面积 为50 m 16 m ,投资还比较大 891. 05万元 。 2 根据实际运行情况 ,普通滤料每半年就需更 换1 次 ,采用覆膜滤料后,滤料至少能正常使用 2 年, 减少了工人的维护工作量 ,同时也避免了因停机换袋 造成的硅微粉的损失 。 3 采用列管式空冷器 , 列管式空冷器占地仅 4. 5 m 4. 5m ,质量60 t ,而且冷却效果能够通过连通 阀调节,确保工况温度达到最佳,这一点,U 型管空冷 器是很难做到的 。 39 环 境 工 程 2005年 2 月第23 卷第1 期 4 回收硅微粉 为了提高除尘器收集粉尘中的 SiO2含量,德昌集团硅铁电炉除尘系统引进了预收尘 器,该设备能够将硅微粉中SiO2含量由 85～ 90 提 高到92 以上。 5 投资回收期 年 投资回收期 680229. 142. 97 a 投资回收期约 3 年 , 说明投资回收速度快, 效果 好。如执行国家规定的“三废”综合利用 ,产品免税, 效益会更好。 6 结语 德昌集团的 2 台 12 500kVA 硅铁电炉除尘系统, 综合国内硅铁电炉除尘现状, 根据实际情况 ,选择了 正压式除尘系统 ,并采用了覆膜滤料及预收尘器新技 术和新设备 ,具有投资省 、 占地小和硅微粉 SiO2含量 高的特点 。 该除尘系统 ,于 2001年 7 月正式建成,10 月正式 投产 。通过监测, 排放浓度为 35 mg Nm 3 , 单台电炉 每天回收硅微粉8 t ,硅微粉SiO2含量达到94, 各项 指标均超过了设计预期值 。 7 改进建议 硅微粉的增密工艺, 挪威埃肯公司在不用添加剂 的前提下能将硅微粉制成直径为 0. 5～ 1 mm 的微细 球,使堆积密度从 0. 2 t m 3 提高到 0. 5～ 0. 6 t m 3 , 可 降低 65 的运输和包装费用。青海某公司经过多年 探索实践, 采用压缩空气处理方法, 可将硅微粉增密 至0. 4 t m 3 左右 。 受投资条件的限制, 该除尘系统目前尚未建设硅 微粉增密装置, 因此 , 特建议条件成熟时建设硅微粉 增密装置。 参考文献 1 中国冶金建设协会主编. 钢铁企业采暖通风设计手册. 北京 冶金 工业出版社. 2 刘天齐主编. 三废处理工程技术手册 废气卷 . 北京 化学工业出 版社. 3 中国有色金属工业总公司主编. 采暖通风与空气调节设计规范. 北 京 中国计划出版社. 4 上海市建设委员会主编. 通风与空调工程施工及验收规范. 北京 中国计划出版社. 作者通讯处 刘圣 617023 攀枝花攀钢集团设计研究院有限公司 电话 0812 3390994 传真 0812 3397767 E -mail liu570418163. com 2004- 03-02 收稿 上接第 37页 4. 2 工程设计参数及运行情况 附表为高压脉冲除尘器设计参数。 附表 宝源热电公司 3锅炉除尘器设计参数 项 目参 数备 注 处理气量 m3h- 1 430 000单台锅炉 烟气温度 ℃150～ 210实际最高204 入口烟气含尘浓度 gNm- 3≤20 出口粉尘浓度 mgNm- 3≤50 本体阻力 Pa900 过滤速度 mmin- 11. 00 有效过滤面积 m27 162 除尘效率≥99 . 8 该袋式除尘器过滤材料采用 HBT 新型复合滤 料,锅炉满负荷运行稳定后 ,除尘器系统总阻力变化 基本稳定控制在1 000 Pa 左右, 远小于国内其它电站 锅炉袋式除尘器的系统阻力 。滤袋进出口压差在 500 Pa 到 900 Pa 之间波动 ,清灰周期约为 25 min, 出 口粉尘浓度 30 mg Nm 3 ,完全符合设计要求。 5 结论 1 由于新型复合滤料采用了“梯次”结构 ,使得 滤料在过滤过程中压力损失小 ,大大降低了除尘器的 能耗和改造费用 。 2 新型复合滤料的“梯次”结构使得在过滤过程 中微细颗粒不至于堵塞到滤料的深层,而且其采用特 殊的后处理技术 ,使其过滤效率 尤其是对于微细粉 尘 与某些覆膜滤料的过程效率相当 。 3 从长远的角度看 ,随着过滤技术和材料技术 的发展,复合滤料在包括燃煤锅炉除尘等复杂场合将 得到更大规模的发展与应用。 参考文献 1 张殿印. 除尘技术手册. 北京 冶金工业出版社, 2002. 2 刘书平. FMS -氟美斯耐高温集尘布袋用过滤毡系列产品的研制及 应用. 全国袋式过滤技术研讨会论文集, 武汉, 2001. 3 中华人民共和国国家标准. GB12625 -90, 洁净滤料阻力、滤料静态除 尘率. 作者通讯处 李华 200051 上海延安西路 1882 东华大学 200 信箱 电话 021 62379260 E -mail lihua mail. dhu. edu. cn 2004- 06-01 收稿 40 环 境 工 程 2005年 2 月第23 卷第1 期 OPTIMIZATION OF WASTEWATER DISPOSAL LINE OF AUTOMOBILE COATING Liu Qidong 23 Abstract The main problems of the er wastewater disposal line of the coating workshop for No. 3 Chang ′an Automobile Factory were analyzed by researching its run status. Wastewater flow and quality were instable;the same disposal made the disposal of the different wastewater more difficult; the equipments were seriously eroded. The differentwastewater was physically and chemically disposed firstly , and then entered SBR reactor and further bio -chemically treated, a series of anticorrosive measures were taken during the equipments prefabrication and the problems were resolved very well in the er wastewater disposal line for the rebuilt wastewater disposal line. Keywords wastewater disposal system of automobile coating and optimization TREATMENT OF SLAUGHTERHOUSE WASTEWATER WITHPROCESS OF FLOATATIONAND SBRZhang Zhaohui et al 25 Abstract The process of floatation and SBR is used to treat slaughterhouse wastewater. When the influent CODCris in the range of 1 200～ 1 850mg L, the effluent CODCrisunder 90 mg L, and all the quality indicationsof the effluent could meetfirst -order of Wastewater Comprehensive Discharge standard GB8978 -1996. Furthermore part of the treated wastewater can be used again. Keywords slaughterhouse wastewater, SBR and air floatation PRIMARY EXPLORATION OF CONSTRUCTION OF MUNICIPAL WASTEWATER PLANT IN AREAS OF LOW-TEMPERATUREZhao Lijun et al 27 Abstract The characteristics of low-temperature municipal wastewater and the effect on wastewater treatment efficiency owing to the change of temperature were introduced, andthe problemsthat should be noticed in selecting wastewater treatmentprocessin areas of low-temperature were pointed out too. Moreover, suggestions on the selection of designing parameters and the running management of project were brought forward. Keywords low -temperature, municipal -wastewater, selection of process and design parameter TREATMENT OF ACIDICWASTE WATER FROM PRODUCTIONOF SEAMLESS STEEL TUBES Yang Weiguo 30 Abstract A complete waste water treatment process is supplied according to the fact that there is a lower pH value and a higher FeO or Fe2O3or Fe3O4in the waste water from hollow billet pickling process in a seamless steel tube mill. Practical running shows that this treatment processis outstanding and this technique is advanced, the treatment result is excellent, and that the processed water can be used for production again. This technique has obvious economic, environmental and social benefits. Keywords hollow billet, pickling waste water and treatment ENGINEERING EXAMPLE OF TREATING ARSENIC -BEARING WASTE WATER Chen Liaoyuan et al 31 Abstract A successful engineering case in which the arsenic -bearing wastewater is treated is introduced. The process, technical parameter and the special design of aerated system are also introduced. This design overcomes the defects in the er design. Keywords arsenic -bearing waste water, FeSO47H2O and aerated system TECHNICAL STUDY ON REMOVING INHALED PM2. 5 USING THERMOPHORESIS IN LAYER FLOW CYCLE CHANNELZhou Tao et al 33 Abstract A kind of new layer flow cycle channel with two cooledwallswas designed onbasic thermophoresis principle. This kind of channel has a higher cumulative efficiency for removing inhaled PM2. 5 than usual channel through calculation. In the meantime, the higher cumulative efficiency for removing inhaled PM2. 5 will be obtained by taking into account developing flow and developed flow of speed temperature at different inlet gas temperature conditions. It is a new way that isworth researching further. Keywords two cooled walls, thermophoresis, inhaled particle matter and cumulative efficiency EXPERIMENT AND APPLICATION OF FILTRATION PERANCE FOR NEW COMPOUND FILTER MEDIALi Hua et al 36 Abstract To decrease the pressure drop and increase filtration efficiency of the filter media in a bag filter, a new compound filter media named HBT was introduced, and the experimental study on filtration perance was carried out. The results indicated that HBT filter media had the perance of high efficiency and low resistance in the same operating conditions, Therefore, it ismore suitable for a coal -fired boiler. Keywords compound filter media, filtration perance, application and coal-fired boiler DEDUSTING ANDINVESTMENTBENEFITOF12 500 kVAFERROSILICONELECTRIC FURNACELiu Sheng 38 Abstract It was introduced that the dedusting technique, main equipment composition and the dedusting system′ s superiority of 12 500 kVA 3 ENVIRONMENTAL ENGINEERING Vol. 23, No. 1,Feb. , 2005 ferrosilicon electric furnace. The investment analysis of recovering microsilicon fume was also conducted. Keywords ferrosilicon electric furnace, dedusting, recovery of microsilicon fume and benefit TECHNICALREOFDEVICEFORTREATINGPELLETINGTAILGASFROM PRODUCTIONOF COMPOSITE FERTILIZERYang Zhongmiao et al 41 Abstract It was analyzed that the problems of phosphoric acid -washing for primary treatment of pelleting tailgas from production of composite fertilizer, and that the causes of large amount of ammonia in the tailgas when water -washing is used for primary and secondary treatments. A technical scheme of using phosphoric acid -washing for secondary treatment is also proposed, whose operations show that the re is successful and using phosphoric acid-washing for secondary treatment is feasible. Keywords pelleting tailgas, ammonia, phosphoric acid and re EXPERIMENTAL STUDY ON FUSION AND PICK-UP BY SOAKING FOR FLY ASH IN MUNICIPAL SOLID WASTE MSWINCINERATIONZhong Zhaoping et al 43 Abstract It isdescribedthat the process of experimental study on the fusion at high temperature for fly ash in municipal solidwaste MSW incineration and the perance of the pick -up by soaking for the fusing dregs. The experiment of fusion is operating in Marver stove, and the experiment of pick -up by soaking is operating in distilledwater, acetic acid,whose pH is4. 5, and sulphuric acid, whose pH is 3. The resultsof the experiments are as follows. The amount of the heavy metal Cd, Cr, Zn, Fe increases asthe time of fusion goeson, the amount separted out decreases obviously. By prolonging the time of fusion, the pollution of these metals can be reduced. Because the heavy metal Hg volatilizes easily, the time of fusion has little effects on its amount separated out. The amount separatedout of heavy metalZn, Cd etc. decreases obviously with its temperature of fusion increasing, so the pollution of these can be reduced by raising its temperature of fusion. The amount separated out of the heavy metal Cr increases with the rising of the solvent s pH,while the amount separated out of Cd, Pb, Zn in acetic acidis the greatest, and water is the smallest. For these heavy metals and acetic acid having complex reactions, so its amount separated out is the greatest. Keywords fusion, pick-up by soaking, MSW incineration and cinder STUDY ONTECHNOLOGY OF PLASTIC SEPARATING AND RECYCLING FROM MSW Lǜ Chuanyi et al 45 Abstract The component of MSW was analyzed, and the necessity of separating plastic and recycling plastic from the MSW wasexpatiated. The new processof separating plastic and recycling plastic from the MSW was brought forward. The motion parameters of separating plastic and the perance parameter of plastic boardwere given. The key techniques, such as crushing, enlacing, changing density and so onwere also solved. The technical inds of the fabricated boards can meet the requirements of building materials. Keywords MSW, plastic separating , changing density , recycling resource and plastic board TREATMENT OF NITROGEN OXIDE WITH SOIL FILTRATIONDu Jijun et al 48 Abstract The biological treatment of nitrogen oxide in waste gas by soil filtration was investigated. The study focused on the effect of soil, concentration, temperature and air velocity through reactor. The experiment result demonstrated that pollution caused by nitrogen oxide canbe controlled by soil filtration. The removal efficiency of nitrogen dioxide was above 90. Enrichment soil was better than poor soil as filtration medium. The removal efficiency was increasedwith increasing of concentration, when concentration higher than 2 mg m3, the removal efficiency was around 95. The increasing of temperature was of benefit to the removal efficiency. On the other hand, it also prolonged the operation time of soil filter. In the range of the experiment, the increasing of gas velocity in the reactor didn t decrease the removal efficiency of NOX. Keywords nitrogen oxide, soil filtration and biopurification DESIGNOFTHEINCINERATIONPLANTFORSOLIDWASTEFROMPUDONG INTERNATIONAL AIRPORTWang Yanming et al 51 Abstract It is introduced systematically that the incineration processfor the treatment of solidwaste from Pudong International Airport. And the process flow and design parameters including material balance and safety control theory have been detailed. Keywords solid waste from airport, incineration technique, material balance and process control PRIORITY LEACHING OF CAMIUM FROM S