# Thermal Analysis of an Industrial Furnace

^{1}

^{2}

^{*}

## Abstract

**:**

## 1. Introduction

## 2. Model Settings

#### 2.1. Geometry Creation

#### 2.2. Meshing Process

#### 2.3. Models for Convection and Radiation

#### 2.4. Boundary Conditions

#### 2.5. Dynamic Mesh

#### 2.6. Control Surfaces

## 3. Results

#### 3.1. Fluids Behavior

#### 3.2. Heat Flux Evaluation

#### 3.2.1. Radiative Heat Flux

#### 3.2.2. Convective Heat Flux

#### 3.2.3. Conductive Heat Flux

#### 3.3. Total Energy Loss and Validation of the Model

^{3}, the flow rate is equal to 165 Nm

^{3}of methane. However the methane consumption calculated is relative to the model created with the ideal operating condition of the furnace. The real behavior instead is conditioned by many parameters such as, for example, the presence of thermal bridges and damaged refractories, which increase the heat flux through the walls. Another aspect is the presence of an interstice between the bogie hearth and the lateral walls of the furnace, which is necessary to avoid friction during movement, but allows part of the heat to exit from the furnace increasing the losses. These, and other phenomena, influence the real consumption of natural gas, increasing the total amount of fuel necessary to maintain the furnace chamber at a certain temperature.

_{2}caused by the combustion of the 165 Nm

^{3}of methane is evaluated. From the stoichiometric equation of the methane combustion results that 1 mol of CH

_{4}produces 1 mol of CO

_{2}(Equation (3)):

_{2}equal to 44 g/mol, results that the combustion of 1 kg of CH

_{4}produces 2.75 kg of CO

_{2}. For a density of the methane equal to 0.73 kg/m

^{3}results that 1 kg of CH

_{4}corresponds to 1.4 m

^{3}of CH

_{4}. So the kg of CO

_{2}produced by the combustion of 165 Nm

^{3}of methane are 331 kg, where 309 kg are due to the combustion of natural gas for the heat lost for convection.

## 4. Application of the Model

_{2}is saved simply with the implementation of a reduced door opening time. A further reduction of this time is not allowed due to the mechanical limits of the door lifting system. The data obtained from this study is also being used for other studies concerning the design of an air knife system to install close to the door.

## 5. Conclusions

## Acknowledgments

## Author Contributions

## Conflicts of Interest

## References

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**Figure 1.**Geometry used for the simulation: (

**a**) The entire domain considered for the analysis, consisting of a fluid domain of the furnace enclosed in another fluid domain which represents the ambient air; (

**b**) Particular of the geometry where the fluid domain of the furnace is shown in grey, while the door is showed in blue.

**Figure 2.**Drawings of a meshed domain: (

**a**) Representation of the entire domain meshed with a conformal method; (

**b**) Particular of the meshed domain near the door which is not included in the meshing process.

**Figure 3.**The three control surfaces created for the evaluation of the convective flow in different zones: (

**a**) Control surface A positioned in correspondence of the exit of the gases from the furnace; (

**b**) Control surface B created in the upper section between the door and the furnace edge; (

**c**) Control surface C created outside the door.

**Figure 4.**The trend of the maximum temperature reached in the surface B and C during the 157 s of the door opening.

**Figure 5.**Sequence of the velocity vectors at different time at the exit of the furnace: (

**a**) Velocity vectors at 0 s; (

**b**) Velocity vectors at 0.5 s; (

**c**) Velocity vectors at 1 s.

**Figure 6.**Velocity vectors of the gases for an opening of 3 cm: (

**a**) Velocity vectors and formation of convective motion; (

**b**) Particular of convective motion at the bottom of the furnace.

**Figure 7.**Fluid motion during the transient time from the opening of the door, up to the complete opening of 4.7 m at 157 s.

**Figure 8.**The velocity vectors’ directions in the air domain that move vertically upwards between the door and the furnace, and immediately outside the door.

**Figure 10.**The convective heat flux evaluated in the three control surfaces created for a complete opening of the door of 4.7 m.

**Figure 11.**Drawing showing the stratigraphy of the walls of the furnace with the decrease of the temperature when the furnace is under operating conditions.

**Figure 12.**Pictures taken during the experimental test made in SdF: (

**a**) The picture is related to a partial opening at 60 s; (

**b**) The picture is related to a complete opening at 157 s.

**Figure 13.**Convective heat flux evaluated on the control surface A for the three different opening of 40 s, 60 s and 157 s.

Component | Height (m) | Width (m) | Depth (m) |
---|---|---|---|

Furnace | 6.9 | 4.7 | 18.55 |

Door | 6.9 | 4.7 | 0.5 |

Enclosure | 25.7 | 16.9 | 30.06 |

Type of Heat Flux | Energy (MJ) |
---|---|

Radiation | 313 |

Convection | 5252 |

Conduction | 41 |

TOTAL | 5606 |

**Table 3.**Energy fluxes evaluated on the control Surface A in the three different case studies for the time of the door opening and the total time.

Time (s) | Energyflux (MJ) | Time (s) | Energyflux (MJ) |
---|---|---|---|

40 | 499 | 640 | 4586 |

60 | 607 | 660 | 4664 |

157 | 1304 | 757 | 5252 |

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## Share and Cite

**MDPI and ACS Style**

Filipponi, M.; Rossi, F.; Presciutti, A.; De Ciantis, S.; Castellani, B.; Carpinelli, A. Thermal Analysis of an Industrial Furnace. *Energies* **2016**, *9*, 833.
https://doi.org/10.3390/en9100833

**AMA Style**

Filipponi M, Rossi F, Presciutti A, De Ciantis S, Castellani B, Carpinelli A. Thermal Analysis of an Industrial Furnace. *Energies*. 2016; 9(10):833.
https://doi.org/10.3390/en9100833

**Chicago/Turabian Style**

Filipponi, Mirko, Federico Rossi, Andrea Presciutti, Stefania De Ciantis, Beatrice Castellani, and Ambro Carpinelli. 2016. "Thermal Analysis of an Industrial Furnace" *Energies* 9, no. 10: 833.
https://doi.org/10.3390/en9100833