Single large roller mill feeds today's jumbo cement plants

The use of a single roller mill to supply kiln feed has always been the most economical approach to new cement plant construction. However, the ability to design and build mills large enough to supply today's 7500+ tons per day cement kilns has sometimes been questioned. The successful start up and operation of the 5.9-m roller mill at P.T. Semen Gresik's Tuban plant, Indonesia, has proven that reliable mills can be built for this application. Years of experience, together with modern computer-aided design techniques, has been the key to opening up the future for large roller mills. Here, the design capabilities needed to successfully produce large mills, as well as the operational features of modern roller mills, are discussed     

Large Mills for Dry Raw Material and Clinker Grinding

The development of grinding mills, especially in the last few years, shows a continuing trend to larger units. Particular attention must be given to the drying process during dry grinding. Several grinding methods are available, depending upon the material to be ground, and the optimum method must be carefully selected in each case. Special consideration must be made with large ball mills to assure the utilization of all waste heat from the kiln for the drying process. In many cases a roller mill represents a good alternative.     

Gearless Drive for a Finish-Grind Mill with a Capacity of 160 t/h

The principle of the gearless drive has already been applied to some large mills. A synchronous motor is ``wrapped' directly around the mill cylinder and supplied by a thyristor frequency converter at approximately 10-percent system frequency. The drive thus operates at the low mill speed and dispenses with interposed gearing.     

球磨机节能策略与控制方法

球磨机是水泥、陶瓷、冶金以及塑料粉末生产等企业中物料粉碎不可缺少的重要设备.目前有相当多球磨机及其拖动系统还处于非经济运行状态.球磨机启动的大电流,运行的低效率,是造成球磨机工作时电能严重浪费的主要因为.针对球磨机工作特点和要求,研究球磨机节能的策略,分析并给出影响球磨机用电效率的3个关键因素:电压、转差和功率因数;在...     

Large Grinding Mill Drives Update

The trend to larger grinding mills with the attendant increase in motor drive horsepower has affected the options for drive equipment. Also the development of large adjustable speed drives has created new possibilities for mill drives. Grinding mill torque characteristics, drive requirements, and torsional excitations of the various types of available drives will be briefly reviewed.     

Update on Finish Grinding with Improved Energy Efficiency

Machinery and equipment suitable for retrofits in existing finish grinding systems and for new installations are described: adjustable diaphragms for ball mills to control the material transfer from the first to the second compartment; static separators for product separation from the mill vent air; dynamic high-efficiency separators for product separation, with and without recirculation of separation air; and high-pressure grinding rolls for pregrinding or for use in a closed circuit. For all equipment, operating results are given with respect to capacity and energy efficiency. These results clearly demonstrate that considerable improvements in existing grinding systems, as well as higher energy efficiencies of new grinding systems, can be accomplished with these features. Capacity increases of existing systems can easily reach 55-68 percent with higher energy efficiency of 25 or 30 percent. For new grinding systems, energy efficiency can be increased by 30 or 35 percent in comparison to the conventional closed-circuit ball milling system. The improved energy efficiency also has a positive influence on the cement quality.     

Operational results of OK series roller mill

Operational results of a series roller mill, the OK36-4, which was installed at the Ofunato plant of ONODA Cement Co. Ltd. in 1988, are discussed. The maximum capacity and the specific power consumption are 137 t/h and 27.2 kWh/t, respectively, for ordinary cement grinding and 103.3 t/h and 32.8 kWh/t, respectively, for high early strength cement grinding. The quality of both ordinary and high early strength cement was the same as that from conventional tube mills. The mill has been operated stably without any problems due to vibration and wear up to the present. The scale-up policy for the OK mill was confirmed to be adequate to predict a capacity of the OK36-4 mill from that of the OK12-2 mill, which is the smallest among the series     

Rotary Grinding Mill and Drive Motor Torque Relationships

An understanding of torque relationships in the operation of rotary grinding mills necessitates a complete analysis of the mill, gear train, and drive motor insofar as torsional load, inertia, and frictional losses are concerned. Ability of a drive motor to develop the required torque is dependent upon its inherent torque characteristics in combination with its electrical supply system. A complete evaluation of both the drive motor and power system is therefore necessary to assure that proper torque will be supplied by the drive motor for the mill requirements.     

钢球磨煤机负荷检测方法的研究及实现

对发电厂现场采集的钢球磨煤机(球磨机)运行时的噪声信号进行分析，发现球磨机的噪声信号能量可以很好的反映球磨机筒内负荷。由于能量的计算量大且不易用数字电路实现，经过推导找到了用FFT变化后的频谱计算球磨机噪声能量的方法，并在此基础上设计了基于DSP的智能球磨机负荷检测仪，经在国内20多台球磨机上应用，收到了良好的效果。     

球磨机少球磨煤节能技术及其应用

为减少火电厂球磨机耗电量及磨球耗损量,提高磨制煤粉的细度,根据球磨机的工作原理,提出使用一种耐磨性极高、磨损均匀的铬锰钨系抗磨铸铁新材料磨球和不同直径的钢球配比,可以在保证出力情况下减少球磨机装球质量,从而降低磨煤机运行电流,实现节能降耗的目的;并通过试验证实了节能效果。     

火电厂球磨机铬锰钨抗磨铸铁磨球的研制与应用

针对目前火力发电厂球磨机磨球存在的问题进行了分析,研制了一种铬锰钨抗磨铸铁新材料.该材料晶粒细小、金相组织均匀、耐磨性优异,用其制作的磨球,运行1 000h直径磨损0.52～1.20mm,并且磨损均匀,可保证磨球级配的稳定,从而提高磨煤效率,减少球磨机装球量,减少磨球消耗.实际应用试验表明:球磨机的装球重量可减少30%～50%,球磨机电耗可降低20%～30%,球磨机的磨球消耗可降低60%～80%.     

Selection criteria for SAG mill drive systems

The various options available for large-horsepower semiautogenous grinding (SAG) mill drive systems are examined, together with their impacts on mill design and relative capital and operational costs. A brief history of large-mill drive systems is given. State-of-the-art mill design and mechanical design considerations are also discussed. A design for fixed-speed or variable-speed operation is presented, and the capital and operational cost factors that influence design are considered. The choice of a drive system is independent on the size of the mill, its critical speed, and the horsepower required. Several areas of concern are outlined for each drive-system design. A criterion for selecting the best design for large mills is developed     

火力发电厂钢球磨煤机弹簧隔振基础的发展与应用

火力发电厂中的钢球磨煤机属于较大的动力机器, 由于其外型庞大, 其基础往往压在主厂房基础上。为了避免磨煤机的振动传到主厂房基础上, 影响结构的正常使用, 同时也为了保证设备的正常运行, 须对电厂中的磨煤机采取隔振措施。钢球磨煤机基础采用弹簧隔振技术是一项很好的隔振措施, 能使动力机器基础结构简单, 施工方便, 还可以减少振动对结构及周围环境的影响, 提高机器的使用寿命, 延长大修周期, 从而取得良好的社会经济效益。     

浅议大容量机组磨煤机选型

介绍了国内电厂磨煤机应用的现状及各种磨煤机的主要特点。通过双进双出磨和中速磨的技术经济比较，提出了双进双出磨为首选机型     

基于PLC的水泥厂粉磨机控制系统设计与实现

针对水泥配料与磨机负荷控制水泥粉磨机这一关键技术问题,选取球磨机为设计对象,采用S7 200PLC作为主控制器,西门子MM420变频器作为调速装置,借助西门子WinCC V7开发工具,设计了一种基于PLC的水泥厂粉磨机控制系统,实现了水泥厂粉磨机在生产过程中对温度、压力和转速等参数的采集、过程控制及质量监控。实践结果表明,设计完成的基于PLC水泥厂粉磨机控制系统,不仅可以直观、清晰显示粉磨机生产工艺流程的各个环节并能进行控制或监控,而且还能对故障进行报警,对于改善工人劳动环境,提高水泥配料自动化水平和水泥粉磨机长期安全运转等具有重要的现实意义。     

The method for determining the ball load and the grinding capacity of a ball-tube mill from the power consumed by its electric motor

The method for determining the ball load and the grinding capacity from the power consumed by the ball-tube mill under operating and emptying conditions is presented. The implementation of this method when grinding gas coals in the ball-tube mill of the ShBM 370/850(Sh-50a) type is discussed.     

钢球配比对制粉系统球磨机运行优化的实验研究

在实验室的条件下,通过调整钢球配比及煤样的磨制时间,得出不同的磨煤指标数据;从分析磨煤机理,得出最佳钢球配比。结果表明,最佳钢球组合应为30 mm、40 mm、60 mm,其最佳钢球配比为1∶3∶1～3∶4∶3;最小制粉单耗与最大磨煤机出力所对应的钢球配比相同;随磨制时间的延长,磨煤噪声增大,磨煤机输出功率逐渐减小,制粉单耗呈增大趋势。     

火电站中磨煤机的运行机理

介绍了火电站的制粉系统中所采用的磨煤机的历史,解释了磨煤机的研磨理论,并从理论和实践上着重介绍了双进双出钢球磨的工作特点。     

燃用山西贫煤电厂采用中速磨制粉系统的探讨

山西贫煤具有低挥发份、较强磨损、较高着火温度的特性.因此燃用山西贫煤的电厂多采用钢球磨制粉中储仓热风送粉或双进双出钢球磨制粉直吹式送粉系统.本文对燃用山西贫煤电厂采用中速磨制粉系统的可行性进行了分析,并提出采用该制粉方式应注意的问题,供业内同行设计借鉴.     

燃用山西贫煤电厂采用中速磨制粉系统的探讨

山西贫煤具有低挥发份、较强磨损、较高着火温度的特性。因此燃用山西贫煤的电厂多采用钢球磨制粉中储仓热风送粉或双进双出钢球磨制粉直吹式送粉系统。本文对燃用山西贫煤电厂采用中速磨制粉系统的可行性进行了分析,并提出采用该制粉方式应注意的问题,供业内同行设计借鉴。