Sintering Department

Sintering department In this department Mr. Baloch gives us valuable info. about the sintering plant controlled by PLC which works as an interface between the DCS and weighing system. Sinter is a material used in IMD(Iron Making Department) for the extraction of iron from m iron ore. It consist of 1. Dolomite 2. Manganese 3. Limestone 4. Moisture The correct quantity of these materials is very important for pure making of sinter so that it can help in extracting more and more iron and to increase production. So this plant is mostly done automation based for that purpose. Normally 2400-2500 ton material is present in the stock and daily 2-3 times the bin is filled which supplies the Weighing hopper. There load cells are connected and by the help of control system the material is inserted. The automation system consist of the main 3 pillars 1. DCS System 2. Weighing System 3. PLC System

DCS (Digital Control System) Here this DCS system is for the SIEMENS S5 PLC. Nowadays HMI(Human Machine Interface is used for interfacing with PLC as in the IMD Depart. This system is used to give input to the plc so that it gives the signal to the weighing system which material to put and in which quantity. It displays the status of the whole sintering plant and the quantity of material present as well as the status of the correct amount of material used. The quantity of moisture required by the material before heating etc. This system works as a computerized manager which is watching and ordering all the actions of the plant. Since in the making of the ore limited quantity of material is used according to demand so this system orders or give signal to the Weighing system to supply that quantity of material. And after that required quantity is supplied then orders the plc to stop that action. Not only it performs this action but also it monitors all the operations and procedures required in the formation of sinter. And wherever the fault occurs then alerts the management to perform action.

Weighing System. Here in sintering Depart the Weighing System is of a German company SCHENCK and is used here for giving correct and accurate amount of input of the materials used in the preparation of sinter. This weighing system is purely based on automation and therefore it helps in getting more productions than done by labor force. This weighing system is PID(Proportional Integrator and Differentiator) controlled through controller. It takes

input from PLC through DCS that which material to be entered by the Weighing Hopper and then with the help of PID controller opens the face of the hopper till the required quantity is achieved. After achieving the required set point, the controller then sends the feed back signal to the DCS system which orders the PLC to switch off the hopper. Also after filling if the level of material gets below the set point then gives the signal to the DCS System to refill the hopper. Here this is not done by automation but manually. There are 24 weighing system in this plant and connected in groups of 12 and in one group it is divided in 3 feeders each so as to monitor easily its working, operation and maintenance. Then the group controller then performs communication of all the 24 weighing systems with the PLC and DCS. The weighing system has the following electronic cards connected. 1. System Card This works here as the CPU. Its programming is done by SCHENCK and it is for every feeder in each group. Here the programming is PID controlled so in short it works as a PID controller. 2. I/O Card Here this card receives input from the PLC through switching and then perform the above action of supplying the material. Here just switching done by PLC and output is given in the form of material dropped by the hopper and after the set point is achieved and material reqd. is inserted then the PID controller gives the feedback back to the DCS to stop the action. PID Controller: The PID controller works on the basis of set point that if the controller achieves the reqd. set point then it gives the feedback signal to perform action. Here this controller is used to control the weighing system, for how much time to turn the hopper on and when the level of the material in the hopper gets below the set point then to turn on the alarm to refill the hopper

PLC(Programmable Logic Control). PLC System here is the backbone of this Sintering plant and is the sole responsible for controlling the plant through automation. Here SIEMENS S5 PLC is used having CPU 945 of series 115u. It consist of 1. 1 Power Supply 2. 1 CPU Module 3. 1 Communication Module (DCS) 4. 2 Communication Module (Weighing System) 5. Master-slave Interface cards 6. I/O Cards The CPU Module here has the PLC programming with is done in STL (Statement List) which is done in DOS mode having programming in coding but not in block format. If any error occur in this programming or fault occur then the DCS system detects where

is the fault and by having flags in the PLC programming, the fault in the programming is reached and fault removed. Communication with DCS is done by the DCS Comm. Module and this module receives all the orders of performing the required switching action. Comm. With Weighing system is done by the Weighing system comm.. module. Through this module the orders of DCS of entering the material is conveyed to W.S and it perform the action required by DCS through switching of 220V Relay. It involves opening and closing of hopper mouth. Not only it perform the above tasks of inserting material but also it is used to run motors according to different time intervals in the plant. For this purpose the master plc is not placed in the main plant but slave plc are connected which are connected to the master plc. Interface cards can only be placed in the master plc and slave programming is also done in the same. 1 Interface cards can control 2 slaves. The many slaves are connected in plant for more and more automation the more these cards are connected. Also there is another master connected in the plant beside the DCS system which conveys this message to the master connected in the Weighing System to perform that task. Both these are connected through the comm. Module. A total of 750 I/O Cards which are performing switching action are connected in the plant. In 1 I/O Card 32 I/O Slots are present in 1 Master and 8 I/O are present in 1 slave. These are responsible to run the whole plant not stop 24 hours. Redundant or backup PLC is also used as a backup or as inverter to work if master fails. PLC Advantage. 1. It saves time 2. It reduces man power. 3. It increases production 4. Faults are reduced in operation with them