NTE (NOL-TEC Europe) Steelmaking Plants:

• Lime and Carbon Injection System

In  steel  making  process, they  inject pulverized lime and carbon into EAF furnaces  for  process  reasons  especially  sludge formation. To inject the mentioned   material   into   the   furnace   under   operation ,  they   need pneumatic force.

Lime  and  carbon  injection  system  is  actually  a  pneumatic   conveying system  which  conveys  pulverized  material  from  the  silos  to   injection lances   of   the  furnace. This   system  is  comprised  of  two  distinct  and independent parts. The first part conveys material from  outdoor  storage facilities to daily bins  inside  the  workshop  and  the  other  part  conveys material from daily bins into the furnace.

The main components of the system include:

>  Siloes and  storage  facilities in which all of provisions for fluidization and inertization are envisaged. The  whole process is under monitoring by  means  of  sensors to  evaluate  temperature  and  pressure  of  the system. In  case temperature exceeds a certain limit about combustible material  like  carbon, Nitrogen injection facilities will be put into action to eliminate  combustion  threat. The  silos are also equipped with level controlling  devices. All  of  silos  have  a  top  silo  filter  on their roof to mitigate dust emission  during  silo  or  transporter  loading cycles. The silos can  be charged both by truck loading device or big bag unloading stations.

>  Transporters  which  are  pressured vessels equipped with level and pressure  sensors. They  receive  material from storage  silos and inject them   into   the  conveying  pipeline. The   indoor   transporters   which receive material from daily bins are equipped with weighing sensors to inject the right quantity of material into  the  furnace  according  to  the set point defined by the operator. The  mechanism  is like LIW feeder in which the weight of the  transporter  is  measured  periodically  in  time and the feedback of the  control  system  controls  quantity  of  injected material    commanding    a    proportioning     valve    underneath    the transporter.

>  Conveying  lines  which  are  equipped with revolutionary NTE patent named  “Air Assist”. The  function  of  this system is to balance pressure of  certain  positions  of the conveying line with transporter and in case the  pressure  drop  is  considerable , compensates   this  pressure  loss injecting   compressed   air   into   the   pipeline. The  advantage  of  this system  is  that  generally  the  conveying  pressure  reduces  compared with  the other technologies and compressed air consumption is saved considerably. Furthermore, the column of material  inside  the  pipeline is broken into several parts with air packs  in  between. So  in  the  case system   stops  due  to  power  failure  or  any  other  reason , it  will  be possible  to  bring back  the system  into o peration  simply pushing the push button without needing to open the elbows to empty the pipeline manually. This problem is very common in pneumatic conveying lines.

>  Control  System which consists of RIO cabinets to collect field signals to  communicate them to the LCP panel under network communication protocols  like  Profibus .  As  RIO  cabinets  are   located   close   to   the equipment, weighing boards are  also mounted inside them. The LCP is equipped  with  IO  and  PLC modules to monitor and control the whole system. The  control  system  is normally based on Siemens technology although it is possible to supply other control systems upon customer’s request.