文献翻译-凝土喷射机自动除尘系统的研制

英文原文Design of Concrete Spraying Machines Automatical Dust-removing SystemQingdong WangCollege of Mechanical and ElectricalHebei University of EngineeringHandan, Chinae-mail: Lanfeng Wei Guimei WangCollege of Arts College of Mechanical and ElectricalHebei University of Engineering Hebei University of EngineeringHandan, China Handan, ChinaAbstractShotcrete operation in coal mine face will produce alarge number of cementdust. One of the main dust productionequipments is concrete spraying machine.In order to decreaseharm effectively from cement dusts generated in the coal mineface. Dust removal technology of concrete spraying machine isresearched in the paper, and a new dust removal system isdeveloped. According to producing cement dust characteristicsin the bolt-spray coal face production process, and throughunceasing technological innovation, dust removing device forconcrete spraying machine used in work site is developed andproduced. .It has obtained obvious economic and socialbenefits.Keywords-Concrete Spraying Machine; Automatical DustRemoving;Technology System DesignIntroduction From industrial ventilation and dust removal point ofview, dust refers to solid particles suspending in the air in acertain period of time. Dust generated from the process ofsolid substances mechanical crushing, grinding, mixing isthe dust source of environment pollution. At present, dust isstill one of the major problems in coal production. Highconcentration dust, especially cement respirable dust, is thedirect cause of pneumoconiosis.Therefore, reducing dustconcentration is necessary, cement respirable dustconcentration in particular.This is also a main technicalproblem.Effective method of cement dust control in coalmine face shotcrete operation has not been found by now.“Coal Mine Safety Regulation”of China provides that:Coal mine enterprises must adopt effective measures tocontrol dust and toxic hazards to ensure workplacescondition meeting national hygienic standard. Dust (total，dust, respirable dust) concentration should meet therequirements in Table 1. Free SiO2 content in dust shouldbe less than 10%, and the maximum allowable concentrationof respirable dust is 3.5 mg/m.It is still more difficult formost mines to meet such standard. Therefore, how toeffectively control dust hazard and reduce dust concentrationin coal mines is an important part of safe production and alsoof great significance to workers health.TABLE I. STANDARD OF DUST CONCENTRATION IN WORKPLACE1.CONCRETE SPRAYING MACHINES MECHANISM OFDUST ARISING AND REMOVAL1.1Mechanism of Dust ArisingMain reasons for dust generated when shotcrete machineworks are as following:dust particles own characteristicsand influence of secondary airflow, shearing generated fromhigh-speed spraying stream driving air around it, interactionof aggregates within high-speed spray stream and collisionbetween materials and the jet plane. From the above reasonswe can see that main dust producing device is shotcretemachine, which produces a large number of cement dust inspray process.1.2Mechanism of Dust removalClassified according to physical and chemical propertiesof dust, cement dust are inorganic minerals; according to sizeof dust particle, cement belongs to dust fall, commonlycalled visibility dust, and its particle size is generally largerthan 10 m.In static air its residence time is shorter andfalling easier and its falling speed is generally believed byacceleration.According to nature of the cement dust mentioned above,dust removal in coal face shotcrete operation is mainly basedon the principle of gravity wet dust removal and inertialforce dust removal. That is to say, according nature ofcement dust, dust falls in gravity settling chamber.Meanwhile, inertia force dust removal is graded inaccordangce with its different speed and combined with wetdust settling chamber through spraying mist. Desired dusteffect can be achieved by means based on the process above.（1）principle of gravity wet spraying dust removalThe simplest kind of gravity wet spraying dust collector isas shown in Figure 1. The size of droplet in dust collectorand relative motion between droplet and airflow containingdust have a significant impact on dust removal efficiency.(2) principle of inertial force dust removalProduction practice and experimental studies have shownthat when airflow containing dust impinges on carrier, theairflow turns off. Dust particles will generate a inertialacceleration in form of centrifugal acceleration.Thusaccelerates separation of dust particles. According to thisprinciple, different types of baffles are set in inertial filter tochange the direction of airflow, then different forms ofinertia force dust collector are made out. Airflow and dustparticles are at same velocity before gas and dust particlesimpinge on the baffle when airflow containing dust flows ininertial filter.Dust falls and separates from air when airflowcontaining dust impinges on baffle B1 and B2. The process isshown as Figure Airflow passes by baffle B1 before airflow containingdust reaches it, and then turns off. Dust particles with largerquality and size continue to maintain forward movementbecause of their large inertia, until impinges on Bj. Dustparticles generate inertia collision and lose kinetic energy,and then falls and seperates under action of gravity.Figure 1. Wet Spraying Dust Collector Structure Diagram1Inlet of Airflow Containing dust；2Spraying Equipment；3Outlet of Purify Airflow ；4Outlet of SludgeFigure 2. Seperation Principle of Dust Particle Impinging on Baffle1Dust Particle d1；2Baffle B1；3Airflow Streamline ；4Baffle B2；5Dust Particle d2；6 Falling Direction of Dust Particle d1；7Falling Direction of Dust Particle d2；Figure 3. Dust Removal System Structure1Upper Dust Cover ；2 Main Pipe for Collecting Dust；3Pressure Air；4Water Source；5Cleaning Exhaust Port ；6 Dust Collector；7Peripheral Dust Collection Hood；8Concrete Spraying Machine；9Loading Port2. SYSTEM DESIGN OF DUST REMOVAL2.1Dust Removal System Structure DesignThe structure is shown as Figure 3.The dust removal system has three points of keytechnology as following:First, the system realizes all-round control of concretespraying machines dust producing, be able to achieve fullclosure of the dust in process of concrete spraying machinesproduction. Therefore, the dust generated is hard to spread.Structure of concrete spraying machines dust collector is asshown in Figure 4.Figure 4. Structure of Concrete Spraying Machines Dust Collector1Upper Cover ；2Upper Box；3Middle Box；4Down BoxSecond, dust collection part uses pneumatic fan toprovide driving power, convenient for field use, thus avoidadding power control switch and powersupply connectionpart.Last, as concrete spraying machine uses only pneumaticfan which completely replaces electric parts to providedriving power, dust removal device of concrete sprayingmachine can meet intrinsically safe requirement.2.2 Pipe Network Configuration Design of Dust RemovalSystem(1) Under the permission of production process and fieldconditions, spraying machine is closed by upper dust coverand surrounding dust collection enclosures, thus can not onlyshorten the length of pipeline and save investment andoperating costs, but also help trap dust and make operation,maintenance and management of the equipment moreconvenient.(2)Dust is produced not only in loading port of thespraying machine, but also in its exhaust port and outlet ofsludge. By analysis, a joint arrangement concentratingsystem as shown in Figure 1 is adopted. The pipe network isrelatively large, and the pipe is relatively long, so air volumecontrol and balance requirements of the system are morestrict. Thus different seamless-steel-tube diameters and airvolume control parts are adopted to adjust reasonablly airvolume according to dust volume generated.(3)Reduce ressistance loss of the system by minimizingthe number of elbows in pipe network system and choosingseamless steel pipe. This method has the advantages ofreducing ventilation resistance, easy collecting dust, reducingdust stuck in transmission, more than 99 percent of the dustcollected able to be transmitted to the process device.(4)A better connection means between air duct and inletof fan is straight pipe gradually expanding or shrinking. As aresult of site constraints, straight pipe connection can bereplaced by inlet chamber in suction vent to avoid excessivepressure loss; When elbow entrance is really necessary,airflow direction and the direction of impeller rotation mustbe consistent, so as not to affect the fan efficiency.(5)Fans export pipeline should not turn directly, ifturning is really necessary, it should turn after outletdeformed tube, and meanwhile turning direction should beconsistent with that of impeller rotation to avoid increasingresistance loss.3.CONSLUSIONMain performance indexs of concrete spraying machinesdust removal system are as following:Total dust fall rate is97.3%, respirable dust fall rate is 96.3%. Airflow processingrate is 107.6 m3/min;airflow processing deviation is -2.2%;air leakage rate is 3.6%; working resistance is 520Pa;working resistance deviation is -5.5%; liquid-gas ratio is 0.19L/m3; industrial noise 83dB; fan static efficiency is 57.4%. Structure, manufacturing quality: waterway system isequipped with water filters; continuous seam weld in box, nogas leakage; surface smooth, bright and clean; spray paintevenly, no defects of bubbles, cracks, paint stripping and soon.New structure and advanced technology application inthe dust removal system of concrete spraying machineimproves dust removal effect on its operating environment.And the system first chooses pneumatic fan to providedriving power to improve security of dust removal system.The system uses fission structure in which dust absorptionand dust removal connects with hose, so it has highenvironment adaptability and is easy to install.The dustremoval system will effectively improve coal minesoperating environment, reduce or eliminate the incidence ofpneumoconiosis and produce good social benefits. Sincethe device haautomatic sifting material function, workersfor sifting can be reduced, and labor productivity isimproved.Ttherefore, it also has obvious economic benefits.To sum up, the dust removal system of concrete sprayingmachine has broad prospects of popularization andapplication.REFERENCES1 Lu Dezhi, Song Zhifang, Li Shaoku, Relationship of Coal DustComposition and Coal Workers Pneumoconiosis,” Chinese Journal ofCoal Industry Medcine, Mar.2008,Vol.11,No.3, pp. 390-3922 “Coal Mine safety Regulation,” State Administration of Work Safety ,China Coal Safety Supervision Bureau, 20053 Xie Jinliang, Wang Huaping, “Application of Spray Mist dustRemoval in mine,” Express Information of Mining Industry,SerialNo.453, January,2007, pp. 86-874 Ma Junsheng, “Integrated Control Technology of Coal Mine Dust,”Shanxi Coking Coal Science& Technology, 2006(6), pp. 45-465 Furuta N,Ii jima A, Kambe A, et al. “Concentrations, enrichment andpredominant sources of Sb and othertrace elements in size classifiedairborne particu-late matter collected in Tokyo from 1995 to 2004 ,”J Environ Monit, 2005, 7(12), pp.1151-1161中文译文凝土喷射机自动除尘系统的研制摘要：在井下采煤工作面进行喷射混凝土的操作将产生大量的水泥粉尘。最主要的产生粉尘的设备之一就是混凝土喷射机。为了有效地降低在采煤工作面产生水泥粉尘带来的危害，有关混凝土喷射机除尘技术的研制已经出现在在许多论文中。并且已经研制出了新的除尘系统 ，根据在采煤工作面生产工程中产生水泥粉尘的特性以及不断的科技创新，混凝土喷射机的自动除尘设备在采煤工作面的应用已经成熟。并且已经获得明显的经济和社会效益。关键词混凝土喷射机；自动除尘技术；研制系统概述从工业通风除尘的观点来看粉尘是指在坚硬物质的机械破碎、研磨、混合的过程中产生的悬浮于空气中的固体颗粒，是环境污染尘土的主要来源。目前，灰尘仍旧是煤矿安全生产存在的主要问题。高浓度粉尘,尤其是水泥呼吸性粉尘、是引发尘肺的直接原因。因此,降低粉尘浓度是非常必要的,尤其是水泥呼吸性粉尘浓度。这也是一个主要的技术问题。在煤矿采煤工作面有效的水泥粉尘治理方法自今还没有研发出来。中国煤矿安全规程规定:煤矿企业必须采取有效措施来控制灰尘和有毒气体的危害,以确保工作场所的条件达到国家卫生标准。粉尘(总含量、灰尘、呼吸性粉尘)浓度应该符合表 1 的要求游离二氧化硅在粉尘中含量应小于 10%,并且呼吸性粉尘最大允许浓度是 350mg/m。对大多数煤矿符合这样的标准仍然是非常困难的。 因此,如何有效地控制粉尘危害,降低粉尘浓度是煤矿安全生产的重要组成部分,也对工人的健康有着重大的意义。表 1，在工作场所的粉尘浓度的标准测量结果（mg/m 3）游离 SiO2 在粉尘中的含量（%） 粉尘总量 呼吸性粉尘101050508080102223.510.50.31.混凝土喷射机灰尘的产生及其去除的工作原理。1.1 灰尘产生的机理混凝土喷射机在工作过程中产生粉尘的主要原因如下：灰尘颗粒自身的特点和受二次空气流动的影响,高速喷射使得驱动空气围绕它产生剪切流、互动的周围聚集在高速喷流和碰撞的材料和喷气式飞机。从上述原因我们能够看出主要产生粉尘的设备是混凝土喷射机，在喷射过程中能够产生大量的粉尘。1.2 除尘机理根据物理和化学性质分类，灰尘和水泥粉尘都是无机矿物；根据粉尘颗粒的大小，,水泥粉尘属于降尘,通常叫做能见度灰尘，并且其粒径一般大于 10m。在静态空气流中其停留时间比较短,其下落更加容易而且下降速度是人们普遍认为的加速。根据上面提到的水泥粉尘的性质,采煤工作面喷射混凝土施工的除尘主要取决于重力湿喷除尘器和惯性力除尘器的的工作原理。 也就是说,根据水泥粉尘的性质，灰尘落在重力沉降室，这时,惯性力除尘设备是根据其不同的速度分级并且通过喷射雾与潮尘结合落到沉降室。因此，要想达到除尘的目的意味着要通过以上的步骤来实现。（1）重力湿喷除尘器的原理图 1 所示是最简单的重力湿喷吸尘器在吸尘器中液滴直径的大小和液滴与含尘气流之间的相对运动在除尘效率中有显著的影响。使用惯性力除尘原理的开采工艺和实验研究表明,当含尘气流与载体紧密接触，气流将关闭。粉尘颗粒,会产生一个离心加速度运动形式的惯性加速度。从而加速度将 粉尘颗粒分离开来。根据这一原理,不同类型的 挡板设置在惯性滤波器上来改变气流的方向,然后就制造出来不同形式的惯性力集尘器。 当含尘气流流过惯性滤波器时气体和粉尘颗粒以相同的速度撞击挡板。 当含尘气流与挡板 B1、B2 碰撞时 灰尘从空气中分离出来落下。图 2 显示了整个过程。在含尘气流到达 B1 之前气流经过 B1，然后装置关闭。质量和尺寸比较大的粉尘颗粒由于比较大的惯性力，使始终保持向前移动,直到撞到 B1 为止。粉尘颗粒产生惯性碰撞而失去动能,然后在重力的作用下分离出来落下。图 1.湿喷粉尘收集器的结构框图1含尘气流进气口；2 喷射装置3洁净气流出口；4污泥等杂质的出口图 2. 灰尘颗粒碰撞挡板的分离原理1粉尘颗粒 d1；2挡板 B1；3气流流线；4挡板 B2；5粉尘颗粒 d2；6粉尘颗粒下降方向 d1；7粉成颗粒下降方向 d2；图 3 除尘系统的结构1上部防尘盖 2集尘的主管道 3压缩空气 4水源 5清洗排气装置 6集尘器 7外置吸尘罩 8混凝土喷射机 9上料装置2.除尘系统的设计2.1 除尘系统的结构设计图 3 的结构所示。除尘系统的关键技术有如下三方面:（1）实现了全面控制混凝土喷射机粉尘的产生、对喷射机喷射过程中产生的粉尘能够达到完全关闭的状态。因此,粉尘的产