Blast furnace is a counter current chemical reactor where semi-processed raw materials like sinter, ore and coke are charged (charging process)) from the top of the furnace and hot blast air is blown (blowing process) in from the lower part of the furnace.
The hot blast air reacts with the descending coke and produces blast furnace gas (CO, CO2) which progressively reduces the iron-oxide of the charged material and produces hot metal (liquid iron). The hot metal, along with the slag (the impurities) is collected in a pit at the bottom of the furnace called hearth from where it is drained out periodically (tapping process) and transferred to steel making shop to produce steel.
Blast Furnace Level2 system is a collection of mathematical & mass-energy balance models which, based on first principles, mathematical equations and numerical methods, simulate the blast furnace process in segments (charging, blowing, tapping) on real time basis. The models extract plant data like flow, temperature, pressure, distance, velocity etc from the field devices and convert them into trends using fundamental principles of physical laws . For example, a Level2 model uses the radar data that measures the filling rate of hot-metal in torpedo and converts the information to the occupancy of the hot metal in the hearth. It displays the liquid level of hearth to the cast–house operators. Another model uses the radar data that measures the depth of charging material from the furnace top and converts the information to show the layer-wise profiles of the charged materials at the furnace top. Another model predicts the direct and indirect reactions, the solution loss and other thermal and reaction parameters of the furnace using the information of charging, blowing and tapping processes.
The Level2 system helps operators to visualize the process of the blast furnace and in turn assists them in operation with better control facilities. Often the system is used in advisory mode which triggers alarms or guides the operators to take early corrective actions. It also assists the process owners to monitor the health and stability of the furnace.
Automation Division of Tata Steel Ltd has developed the Level2 system of Blast Furnace and implemented at H –Blast Furnace at Tata Steel Jamshedpur. The Level2 system is in operation since 2008. The capacity of H- Blast Furnace is of 2.8 MTPA with 3500 CU. MT of working volume.
Blast Furnace Level2 System is built on following basic features :
This model computes the optimal composition (by weight) of the burden using the available raw materials and achieving the target basicity and hot metal composition
Stock House Matrix Editor - The Stock House Matrix Editor is the facility to the operators to prepare the stock-house matrix.Here the old matrices can be reused, or a new matrix can be created.
Download of Stock-House matrix to Level 1 - The stock-House matrix can be downloaded to Level1 system from the Level 2 Client PC. All used matrices are reserved in Level2 system for re-use.
Burden Profile Monitor - This model generates the radial distribution of burden layers determined from trajectory path of the discharged material. The model is useful for determining the distribution of the charging material at the throat level prior to it's actual discharge to the furnace.
Burden Descent Monitor - This model shows the progressive movement of the charging matrices within the furnace.It shows the position of each charged matrix, predicts the slag and bosh basicity and composition due to each burden composition within the furnace. This model is used to control the PCI rate in order to maintain a uniform fuel rate.
Mass and Energy Balance - This model determines the furnace operating line, indirect & direct reduction, theoretical minimum fuel operation points, solution loss. The model displays the RIST diagram of the furnace based on parameters of last eight (8) hours.
Liquid Level Monitor - This model determines the levels of hot metal and slag in the hearth based on the computed hot metal and slag inflow using mass balance, hot metal outflow using the radar level sensors for the torpedoes, slag outflows through the granulation plant, torque measurement and hearth geometry.
Hearth Wear Monitor - This model computes the hearth lining profile using the hearth thermocouples. The computation is made using Finite Element Method.
Stove Heating Control - The stove model controls the stove heating based on the model computed energy states of individual stoves and the aim hot blast temperature, blast flow and the running blast cycle.
Heat Loss Monitor - This model computes the segment-wise heat-losses from the furnace wall (hearth, tuyeres, bosh, belly, shaft, throat etc.) using the cooling circuit water flow, inlet and outlet temperature of the water flows. It determines the fuel equivalence of the heat losses through wall. It is used to control the fuel rate during the shutdown time.
Water Ingress Monitor - This model is used for early detection of leakage of water through tuyeres.
BF_Level2 System includes the following interface features: