upstream of the mill serves as controlled variable for the return gas quantity with the return gas damper as final control element.
为获得稳定的产品质量，有必要在操作磨机时保持稳定和有效的热风量。除了其它措施，也可以加入必要量的循环风量至热风炉出来的热风中实现。磨机前的静压作为循环风量的控制变量，而循环风阀门作为循环风量的最终控制手段。
During operation of the grinding plant it is necessary to find out the optimal solution between efficient grinding, which is reached with a low material bed and high grinding pressures, and a high degree of smooth running.
在粉磨系统的操作中，在料床厚度和碾磨压力，以及平稳运行之间，找出有效碾磨的最佳操作方法。
Some materials are susceptible to overpressing. This means that no grinding progress is to be expected with increasing grinding pressures. Consequently, an identical product quality can be achieved at a lower grinding pressure, and the specific power requirement going down accordingly.
有些料易受过压影响。这意味增加碾磨压力不会对碾磨效率有多大影响。因此，在用较低的碾磨压力达到相同的粉磨质量的话，相应的额定电耗会下降。
The external circuit via the bucket elevator should be used as far as possible because
mechanical material handling requires less energy than pneumatic material handling to the separator. The quantity of the material being recirculated should amount to approx. two times the new material quantity. The quantity of recirculated material can be influenced by the se-lection of the dam ring and the gas velocity in the nozzle ring. A lower gas velocity caused by a larger, free cross section of the nozzle ring results in a higher quantity of recirculated mate-rial.
应尽可能通过提升机增加外循环物料量，因为机械提升物料相对用气力提升物料至选粉机只需较少的能耗。循环物料量应该是磨机喂料量的约两倍。循环物料量受所选择的挡料圈高度和喷嘴环处的气体流速影响。大截面，小阻力的喷嘴环使得通过的风速降，从而导致大的循环物料量。
Another goal to strive for is safe removal of the fine iron particles from the external circuit. If only an insufficient quantity of iron particles is removed, the specific power requirement will go up.
另一个努力争取的目标是安全地从外部循环中除去细铁颗粒。如果铁颗粒去除的不够，则额定能耗会上升。
3.2 Start-up / Shutdown sequence 启动/停机顺序
3.2.1 Start-up sequence 启动顺序
The exact sequence of mill start-up is shown in the process functional diagrams. The listed order comprises the general sequence steps for a start-up procedure.
正确的磨机启动顺序显示在工艺流程内。表中列示的是常规的开机顺序步骤。 Start-up conditionsContinuous Start-up激活 运行状态 conditions继续条件 Start of oil lubrication system for mill None None 1 gearbox 无 无 启动磨机减速机的油循环系统 伯利休斯水泥 第 31 頁，共 37 頁
2 3 Start of auxiliaries: 附件设备启动 _ Hydraulic system of mill磨机液压系统 _ Separator drive unit选粉机传动 _ Coarse feed valve 粗料进料阀 _ Fine iron particle removal 颗粒铁去除 _ Recirculating bucket elevator 外循环提升机 _ Circulating lubrica-tion of grinding roll-ers 磨辊循环润滑油 _ Confining air fans 启动密封风机 Start of product handling 启动成品输送 None 无 None 无 None 无 Silo level < Max/Max库料位小于最大值 4 5 6 7 _ Temperature downstream of mill < Max/Max _Temperature down-磨机后温度小于最streamof mill < Max 大值 磨机后温度小于 _ Temperature 最大值 downstreamof filter _ Group product han-< Max/Max dling works 袋收尘机后温度小Start gas routes 成品输送组工作 于最大值 启动废气处理 _ Group auxiliaries _ Group product works handling works 附件设备组工作 (timer) _ Compressed air sys-成品输送组工作tem> p min (定时) 压缩空气大于最小_ Group auxiliaries p值 works(timer) 附件设备组工作(定时) Group gas routes Group gas routes Start hot gas producerworks works 热风炉起动 废气处理工作 废气处理工作 Heating of grinding plant加热碾磨车间 _ Level slag silo _ Group product > Min/Min handlingworks 矿渣粉库料位大于Start of group mill 成品输送组工作 driveunit and mill feed 最小值 磨机主传动和进料 _ Level gypsum silo _ Group gas routes works 启动 > Min/Min 废气处理工作 石膏库料位大于最_ Material feed in 小值 伯利休斯水泥 第 32 頁，共 37 頁
_ Group product han-operation dlingworks 进料在运转 成品输送组工作 _ Main mill drive _ Group gas routes works works 磨机主传动工作 废气处理工作 _ Group auxiliaries _ Material feed avail- works附件设备组able进料有效 工作 _ Group auxiliaries works附件设备组工作 _ Temperature down-stream of filter > 80°C 袋收尘机后温度大于80°C 8 Hydraulic system of mill set to working Main drive unit worksMain drive unit workspressure 磨机主传动工作 磨机主传动工作 磨机液压系统设定至工作压力
3.2.2 Shutdown sequence 停机顺序
In principle, shutdown of the grinding plant is made in reverse order. For normal shutdown of the roller mill, material feed must first be reduced to approx. 60-70% of the rated throughput. When stopping the material feed, operation of the main drive unit of the mill is stopped si-multaneously.
原则上，粉磨系统的停机顺序是相反的。正常的立磨停机时进料量必须减至大约通过量的60~70%。当停止进料，磨机的主马达装置同步停止。
The detailed shutdown program for normal stopping of operation, including EMERGENCY-OFF is contained in the process functional diagrams.
正常操作时的详细停机程序（包含紧急停）在过程控制功能块流程中介绍。
3.3 Control loops控制回路
伯利休斯水泥 第 33 頁，共 37 頁
The following control loops are provided and described below: 所提供的下述控制回路介绍如下：
3.3.1 Control of differential pressure of mill 磨机压差的控制
The differential pressure of the mill is the best indication for the filling ratio of the mill. For
伯利休斯水泥 第 34 頁，共 37 頁
this reason it is extremely important to use the differential pressure control from the very beginning of commissioning. After the first operating hours, the differential pressure typical for the respective mill is very quickly reached so that this value can serve as basis for further optimisation.
磨机的压差是磨机内物料填充率的最好指示。因此，从调试开始就采用压差控制是非常重要的。磨机运行几小时后，针对该磨机的进出口压差值特征就显示出来， 它被用作进一步优化的基础。
If the differential pressure is so low that there are still reserves available in the static head of the fan, the set point of the differential pressure controller can be slowly raised, i.e. the feed quantity is slowly increased without changing the grinding force.
如果压差太低，仍有保留可利用的风机静压头，压差设定控制器可以慢慢地提高，在不改变碾磨压力情况下，慢慢地增加进料量。
The limit of the differential pressure has been reached as soon as the following conditions exist: specified static pressure head of the fan has been reached, too much fines pass through the nozzle ring, or the power consumption of the main drive unit exceeds the maxi-mum value.
当存在以下情况时，会出现压差达到极限值：风机的额定静压头已经达到；太多的细粉通过喷嘴环；或者主电机的电耗超过最大值。
In such a case it is necessary to reduce the feed quantity because otherwise the mill will fail as a consequence of overfilling.
在这种情况下必须减少进料量，因为不然会发生填料过载的后果。
The correct value of the differential pressure of the mill having been reached, the mill
throughput should only be varied by changing the grinding force. A reduction of the differen-tial pressure of the mill can be attained either by increasing the grinding force (better grinding result) or by reducing the feed quantity.
正常的磨机进出口压差已达到时，磨机产量只能通过改变碾磨压力来实现。要降低磨机的压差可以通过增加碾磨压力(更好的碾磨结果)或者减少进料量实现。
3.3.2 Control of temperature downstream of mill 磨机出口风温的控制
The purpose of the control is to keep the temperature downstream of the mill constant on a preset setpoint level (approx. 90°C). The manipulated variable is in this case the fuel gas supply to the hot gas producer.
控制的目的是为了保持出磨风温维持在设定值(大约90°C)。此种情况下，热风炉的燃料共给是控制出口温度的操作变量。
A certain quantity of hot gas is required for the combined grinding and drying process ac-cording to the moisture content of the material. Sufficient drying of the material can be con-sidered in the case of a gas temperature of approx. 90°C downstream of the mill. If the tem-perature increases too much, fuel gas supply to the hot gas producer will be throttled until the requested temperature level has been restored. On the other hand, the fuel gas temperature will be increased if the temperature downstream of the mill goes down too much.
根据物料的水份含量，在粉磨和烘干过程中需要一定的热风量。有效的物料干燥可以认为出磨后的气体温度保持在90 °C。如果温度上升太快，供给热风炉的燃气将被节流阀调节减少，直到所需的风温被保持。相反，若出磨后的风温降低太快则燃气增加热风温度会提高。
3.3.3 Control of pressure upstream of mill 磨机入口前静压的控制
伯利休斯水泥 第 35 頁，共 37 頁