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.