Exchange Rate Design for Thermal Workshop Equipment

Contents

Contents

Task

Introduction

Design of pushing methodical furnaces

1.1 Furnace channel profile

1.2 Structure of hearth and conveying devices

1.3 Metal Heating Mode

1.4 Glide tubes

2 Furnace calculation procedure

2.1 Calculation of fuel combustion

2.2 Metal Heating Time

2.2.1 Determination of metal heating time in the methodical zone

2.2.2 Determination of metal heating time in welding zone I

2.2.3 Determination of metal heating time in the II welding zone

2.2.4 Determination of Metal Languishing Time

2.3 Determining the main dimensions of the furnace

2.4 Heat Balance

2.5 Recuperator calculation for air heating

2.6 Burner Selection

Conclusion

List of sources used

Contents

Introduction

1. General part

1.1. Characteristics of pusher furnaces

1.2. Furnace mechanisms

2. Design part

2.1. Source Data for Calculation

2.2. Calculation of fuel combustion characteristics

2.3. Calculation of basic furnace dimensions

2.4. Calculation of metal heating time and furnace temperature mode

2.5. Heat balance and determination of fuel consumption

2.6. Calculation of furnace performance indicators

2.7. Selection of burners

Conclusion

List of literature used

Job for coursework

1. Provide general information on the furnaces as well as a brief description of the furnaces

2. Design of pushing methodical furnace of ferrous metallurgy, operation of furnace and use of furnace in production

3. The principle of operation and arrangement of the pushing methodical furnace, its productivity and technical and economic indicators in production

4. Furnace Calculation Procedure

Introduction

A furnace is a process equipment in which the working type of energy is heat and the working space of which is protected from the environment. The variety of industrial furnaces used in the foundry makes it necessary to subdivide them into major groups.

According to the method of heat generation, all furnaces are divided into fuel ones, where heat is released due to fuel combustion, and electric ones, where electric power is converted to heat by an electric arc, heating resistance elements or induction.

According to heat transfer conditions, furnaces are divided into furnaces with heat transfer mainly by radiation and convection.

The operation of the furnaces is characterized by thermal power, thermal load, temperature and thermal conditions.

According to the thermal mode, the furnaces are divided into furnaces operating according to the chamber mode and furnaces operating according to the methodological mode. In furnaces operating in the chamber mode, the temperature of the working space remains constant throughout the operation of the furnace. In furnaces operating according to the method, the temperature in the furnace varies over the length of the furnace or over time.

Methodical heating furnaces are widely used in rolling and blacksmithing shops for heating square, rectangular, and sometimes round blanks.

According to the method of metal transportation, methodical furnaces belong to the so-called passing furnaces. A series of contiguous blanks fills all under the furnace and is advanced through the furnace by means of a pusher. When loading a new preform into the furnace, one heated preform is discharged from the furnace.

The most important classification features of methodical furnaces are:

1) furnace temperature mode (in length);

2) bilateral or unilateral nature of metal heating;

3) method of metal discharge from furnace (lateral or end outlet).

In addition, the classification is carried out according to the type of preforms to be heated, the method of heat recovery of exhaust flue gases, the type of fuel, the number of rows of preforms in the furnace .

Conclusion

Technical and economic evaluation of methodical furnaces

The widespread use of methodical pushing furnaces is due to the fact that these furnaces provide a sufficiently high productivity at a low specific fuel consumption, as well as provide a high coefficient of heat use in the working space. This is due to the presence of a methodological zone.

The use of glide tubes with raters increases the uniformity of metal heating (without scratches and cold spots) and creates the prerequisites for increasing the width and length of the furnace.

However, all pusher type process furnaces have disadvantages due to the inability to quickly discharge metal from the furnace and the difficulty of moving from heating slabs of one size to heating slabs of another size. These problems can be solved only when using methodical furnaces with walking hearth.

Summary

In this work, a quenching unit based on the TTO210.960.12/9.3G pushing thermal furnace was designed. The fuel was calculated: the amount of air, the amount and composition of combustion products and their temperature. The duration of metal heating and the main dimensions of the furnace are determined. The heat balance of the furnace and its capacity are calculated, on the basis of which the fuel consumption and to the point of the furnace are determined. Fuel incinerator is selected. Hardening tank parameters are calculated. The drawings of the general view of the unit and the devices included in it are also presented .

Introduction

A furnace is a process equipment in which the working type of energy is heat and the working space of which is protected from the environment. The variety of industrial furnaces used in the foundry makes it necessary to subdivide them into major groups.

According to the method of heat generation, all furnaces are divided into fuel ones, where heat is released due to fuel combustion, and electric ones, where electric power is converted to heat by an electric arc, heating resistance elements or induction.

According to heat transfer conditions, furnaces are divided into furnaces with heat transfer mainly by radiation and convection.

The operation of the furnaces is characterized by thermal power, thermal load, temperature and thermal conditions.

According to the thermal mode, the furnaces are divided into furnaces operating according to the chamber mode and furnaces operating according to the methodological mode. In furnaces operating in the chamber mode, the temperature of the working space remains constant throughout the operation of the furnace. In furnaces operating according to the method, the temperature in the furnace varies over the length of the furnace or over time.

Methodical heating furnaces are widely used in rolling and blacksmithing shops for heating square, rectangular, and sometimes round blanks.

According to the method of metal transportation, methodical furnaces belong to the so-called passing furnaces. A series of contiguous blanks fills all under the furnace and is advanced through the furnace by means of a pusher. When loading a new preform into the furnace, one heated preform is discharged from the furnace.

The most important classification features of methodical furnaces are:

1) furnace temperature mode (in length);

2) bilateral or unilateral nature of metal heating;

3) method of metal discharge from furnace (lateral or end outlet).

In addition, the classification is carried out according to the type of preforms to be heated, the method of heat recovery of exhaust flue gases, the type of fuel, the number of rows of preforms in the furnace .

During the course project the following tasks are set:

Deepening of theoretical knowledge obtained in the study of equipment for thermal treatment of mechanical engineering products;

Study of structures of modern thermal furnaces;

Acquisition of engineering skills for furnace units;

Mastery of methods of thermal and engineering calculations.

General part

1.1 Characteristics of pusher furnaces

Pushing furnaces are installed in front of most small-grade, wire, grade and sheet mills at domestic metallurgical plants. These furnaces are characterized by countercurrent movement of heated metal and combustion products, as well as the presence at the beginning of the furnace (from the side of the metal landing) of a developed unheated methodical zone, as a result of which they are often called methodical furnaces. In modern heating pusher furnaces, these principles are not always strictly observed. For example, straight-flow and mixed direct-flow heating zones are created, burners are installed in the methodical zone. However, in general, the distinctive features of these furnaces remain, and the basic principles of calculation remain the same.

Heating pushing furnaces are classified by the presence of lower heating and by the heat-technical mode of metal heating (dual-zone and three-zone modes). In addition, the furnaces are separated by the heating method (end, roof and side), and in end heating, when the heating zones are clearly expressed structurally, the furnaces are also classified by the number of heating zones (two, three, etc.).

The presence of lower heating determines the nature of the boundary conditions for the heated metal. Metal up to 100 mm thick is heated on one side in furnaces without lower heating, and > 100 mm thick - on two sides in furnaces with lower heating.

Note here that metal is pushed over lower zones via water-cooled bottom pipes to organize lower heating. As a result of the cooling and shielding action of the hearth pipes, relatively cold areas - "dark spots" - are formed on the metal. To eliminate them and increase the uniformity of heating at the end of the furnace (along the metal), a single-sided heating section is created on a monolithic hearth, where in the absence of hearth pipes, temperatures in the metal are equalized. Thus, the temperature unevenness created by the hearth tubes significantly affects the temperature distribution in the metal and thereby the heating time. Therefore, the influence of hearth pipes on the temperature field in the metal must be taken into account in the calculation.

Heating method and number of heating zones determine distribution of combustion products temperature along furnace length.

Conclusion

The pushing furnaces are relatively reliable in operation and sufficiently tight, which is ensured by the relative simplicity of the design and the absence of transporting mechanisms in the working chamber. The main disadvantage is the need to use expensive pallets of heat-resistant steels and significant heat costs for their heating (2030% of the total heat input).