'Thermal Analysis' simulation project by aferreira


#1

I created a new simulation project called 'Thermal Analysis':

Profile thermal of the steel landle of the steelwork


More of my public projects can be found here.


#2

Overview

This work aims to present some modifications made in the steel ladle of Siderúrgica Norte Brasil aiming to increase its nominal capacity and, consequently, to increase the steel production of the steel mill. After an analysis of the layout of the melt shop, it was verified that it was possible to increase the edge of the steel ladle by 100mm, which means a gain of 0,26m3 in its nominal volume. Through a thermal analysis using finite element methods it was found that it was possible to change the refractory configuration of the ladle in order to increase its internal volume without increasing the external working temperature of its metal housing. The result was a gain of 0.15m3 in its nominal volume. There was a real increase in production of 1,7 tons of steel per run.

Geometry

Aiming to increase the nominal volume of the pot was proposed a reduction of the permanent refractory brick from 83mm to 63mm. However, reducing the size of the refractory means increasing the external working temperatures of the metal housing of the ladle, which, consequently, increases its thermal-structural deformation. According to AISE Standard No. 9, Specifications for design of hot metal ladles [3], the maximum working temperature for ladles of nominal capacity up to 100t and thickness of 25.4mm is 673.15K, characteristics that fit the ladles of the Sinobras.

To reduce the permanent refractory while maintaining the structural safety of the ladle and its maximum working temperature in accordance with the standard, the addition of an 8mm thermal insulation in its refractory configuration is proposed. With such changes, the ladle would gain 0.15m3 in its nominal volume, about 1.06 tons of steel. Figure 2 shows the configuration of the refractory before and after the changes.


Figure 1: 3D steel ladle geometry and Mesh


Figure 2: Configuration of the refractory bricks (a) before and (b) after the proposed changes

Boundary Conditions

Firstly, it is necessary to verify if the new configuration of refractories attends the conditions proposed by the standard. In this way, a thermal profile analysis was carried out using the finite element method in steady state mode using the SimScale cloud-based software.

Based on the last companies, it was considered a rate of wear of the working brick in the slag line, which is the most critical region, of 1.3mm per run was considered, and it was also considered that the ladle is removed for repair with 85 runs. The refractory was thus modeled with 152mm at the start of the campaign and 41.5mm at the end.
The thermal conductivity data of the refractories and the metal housing were raised according to the maximum working temperature for application in the boundary conditions in the modeling.

Table 1: Thermal conductivity [W/m.K] according to the temperatures
table

The boundary conditions used to modeled the heat flux problem being exchanged with the natural convection and radiation refrigeration fluid were:

  • Steady-state regime;

  • Conduction of heat through refractories and sheet metal;

  • Natural convection and radiation by the sheet metal in contact with ambient air;

  • Constant ambient temperature equal to 323,15 K;

  • Temperature of the liquid steel equal to 1923,15 K;

  • The ladle was considered cylindrical and the imperfections of refractory assembly were disregarded;

  • Working refractory thickness of 152mm, beginning of campaign and 41.5mm, end of campaign;

  • The thermal conductivity coefficient of the working refractory is 1.98 W / mK, backfill equal to 1.38 W / mK, permanent refractory equal to 1.29 W / mK and insulation equal to 0.2 W / mK.

Results


Figure 3: Thermal ladle profile before proposed changes in (a) the beginning of the campaign and (b) the end of the campaign. Thermal profile of the ladle after the proposed changes in ( c) the beginning of the campaign and (d) the end of the campaign.

Before the proposed changes the maximum temperatures in the ladle shell was 610K at the beginning of the campaign, refractory work with 152mm, and 722K at the end of the campaign, refractory work with 41.5mm. After the proposed changes the maximum temperature in the ladle housing was 604K at the beginning of the campaign and 699K at the end of the campaign, refractory of work with 41.5mm. Both at the beginning of the ladle campaign and at the end the proposed refractory configuration did better than the standard configuration. However, according to the standard, in both cases the temperature at the end of the campaign is above the permissible values.

The amount of production per run was monitored before and after the proposed changes, comparing the first 85 runs of the 3rd ladle, the ladle without changes, and the 2nd ladle, the ladle with the alteration, the results are presented in the Graphic 1.

graph
Graphic 1: Comparison between the amount of steel produced from ladle 2 and 3.

On average, there was a gain of 1.8 tons of steel per run. A standard deviation for the 3rd ladle of 1.6 tons and for the 2nd ladle of 1.7 tons. The gain calculated numerically with the changes in the geometry of the ladle and the refractories were 0.4m3, or 2.8 tons. In this way, it can be seen that there was a difference of one tonne of steel between what was expected to be gained from the changes and real gains, mainly due to the variations in the operational process of steel tapping, quantity of liquid foot and volume of slag in the FEA.

  • After analyzing the layout of the steelworks it was verified that it was possible to increase the edge of the ladle by 100mm by removing the last two refrigerated rings from the FP.

  • The working temperatures of Sinobras S.A steel ladles when at the end of the campaing exceed the permissible limit of 723,15K, as seen in the computational simulation.

  • Working temperatures with the new refractory configuration fall by about 6K at the beginning of the compaign and 23K at the end of the campaign compared to the temperatures of the ladle before the size of the permanent refractory brick and the addition of the insulation changed. That is, even after the reduction of the permanent refractory brick the maximum temperature of the ladle was lower than the temperature of the ladle with standard configuration due to the addition of the refractory insulation, which validated the proposed change to increase the nominal volume of the ladle.

  • With the increase of the edge of the ladle in 100mm and with the reduction of the permanent refractory brick from 83mm to 63mm there was an analytical gain of 2.8 tons of steel in the nominal capacity of the same. However, actual production gains were, on average, 1.7 tons of steel.

Acknowledgments

Siderúrgica Norte Brasil and Federal University of the South and Southeast of Pará.


#3

Hey
I like table 1 description,wonderful.Stunning result!
A lot work already done,keep going
All the best JonWalter