USS Serbia, Smederevo, Sinter line 4 control system reconstruction and modernization

High efficiency of the burning process at the Blast furnace plant can be achieved by providing constant parameters of the income material, e.g. sintered ore. During sintering process the iron ores are thermal  treated, the carbonate, sulfide and oxide molecules are dissociated, and the final goal is to provide “self-melted” sinter material which is smelted easily at the Blast furnace plant.The project task was the reconstruction  and modernization  the sintering and cooling line for iron ores, with griddling and transporting  classified material toward the blast furnace.



The raw material comes over conveying system to the Sinter plant, level 36m; with water regulating valve it is wetted in the Secondary mixer drum, and transported by the Heat distributor into the Flow hopper. The regulated drive of the Drum feeder takes it from the hopper, and feeds the cars of Sinter-machine conveyer; this conveyer steadily carry the mixed ore into the Furnace, over 18 Vacuum chambers, and delivers it to the Crusher.Furnace is a set of burners, located over first four  vacuum chambers. It is fueled with natural gas or blast furnace gas, which is combined with air to create an optimum burning mixture. The gas and air regulated valves are provided for the temperature regulating loop.

The crusher breaks up the processed sinter material and feeds it to the Line cooler.The main part of the line cooler is the regulated-drive-conveyer, which is equipped with 8 cooling fans, and designed to cool the processed material and deliver it to Self balance screen; after classification the material is transported to the blast furnace.

During each of the sintering phases, the process of filtering is performed; two Electric precipitators , together with the Knock-off devices and conveyer system are used for dust cleaning. The middle voltage motor Fan sucks the dust air through filters.

The control system regulates the material level in the bin according to signal input from level sensor, and controls two Dosing Scale Conveyers to provide the regulated flow of material into the secondary mixer.

The control system commands to water regulation valve according to requested water flow ratio from moisture regulating loop (cascade control systems)

The sinter process is regulated by controlling the speed of the sinter machine conveyer, according to target temperature profile in all 18 chambers, with the peak value at 17th.

The control system commands to air regulation valve and gas regulation valve according to requested fuel-air ratio from the temperature regulating loop.

Control system is realized with decentralized architecture; the heart is Master PLC, where the control algorithm is executed; PLC communicates over Profibus DP (optical cable) with 8 distributed and decentralized I/O nodes. The exception is decentralized node at electric precipitation location, e.g. that is separate PLC which communicates with master as Intelligent slave.

The decentralized periphery is located at separate and distributed control cubicles Each of them, together with master PLC,  consists of  several digital and analog I/O signal modules. The total number of  I/O signals is:
  • 1275 digital inputs, with relay interface
  • 248 digital outputs, with relay interface
  • 137 analog inputs, with isolating amplifiers (including thermocouple and Pt100 signals)
  • 8 analog outputs

Two 15” color-screen touch panels are used for process control and monitoring. The visualization and data logging is performed with SCADA system, which consists of two clients and one server PC. The HMIs, SCADA PCs and master PLC establish an Profinet LAN.



The sinter line control system reconstruction and modernization process consisted of the following phases:

  • Dismantling of the old control system, cable inspecting with eliminating  damaged and unnecessary cables
  • Electric design phase
  • New cable trays, pulling new cables (signal and energetic, total length approx. 22km)
  • Pulse line test and reconstruction, delivery and assembly  pressure, flow and temperature sensor devices (29 Siemens Sitrans sensors, 45 temperature sensors)
  • Delivery and assembly  two dozing scale conveyers Siemens Milltronics, capacity 200t/h
  • Delivery and assembly a moisture sensor
  • Delivery and assembly  6 AC motors for the drum feeder, sinter machine and line cooler drives (instead of old DC motors)
  • Production, delivery, assembly and connecting  11 control cubicles and MCCs, 2 control pulpits and approx. 70 local pulpits
  • Control algorithm software realizing, Factory acceptance test (FAT), Site acceptance test (SAT), cold tests and production phase commissioning

Since the contracted term the job finishing was 170 days, some phases had been overlapped (dismantling and electrical design, electrical design and control panel production phase, e.t.c.). Although, the complete job was done in 150 days.

The Mikro Kontrol engagement was as follows:

  • Electrical engineers …… 9000 hours at the Site, and at the bureau
  • Electricians …………… 13000 hours at the site
  • Electricians …………… 5000 hours at the Factory
  • Mechanicals ……………1000 hours


Vase Pelagica 30
11000 Belgrade, Serbia
+381 (0)11 3699 080
+381 (0)11 3699 939
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