Thermal Design Calculation of Thermal Furnace

Contents

INTRODUCTION

1 DEVELOPMENT OF TEMPERATURE SCHEDULE

2 CALCULATION OF FUEL AND DETERMINATION OF ACTUAL TEMPERATURE IN FURNACE

3 DETERMINATION OF HEATING TIME

3.1 Calculation of heat exchange process of furnace working chamber

3.2 Calculation of the residence time of the cage in the working space of the furnace

4 PROFILING OF FURNACE WORKING SPACE

5 HEAT BALANCE. SELECTION OF BURNER DEVICES

6 RECUPERATOR CALCULATION

7 AUTOMATIC CONTROL OF FURNACE HEAT LOAD

8 TECHNICAL AND ECONOMIC INDICATORS

CONCLUSION

LIST OF LITERATURE USED

APPENDIX A

APPENDIX B

APPENDIX B

APPENDIX D

APPENDIX D

EXHIBIT E

APPENDIX G

APPENDIX Z

Introduction

Thermal furnaces serve to heat materials for thermal or chemical-thermal treatment.

Thermal furnaces are divided into quenching, tempering, annealing and normalization furnaces, cement, etc. All of them are classified by degree of mechanization and structural design into chamber, conveyor, pusher, with walking hearth, etc.

As fuel in thermal furnaces, various grades of gas are most often used, but fuel oil is also sometimes used.

A large number of thermal furnaces of machine-building and automotive enterprises of the country work on electric energy. However, the feasibility of its use should be economically justified in each individual case.

Thermal furnaces have higher requirements for the accuracy of heating and cooling, so more careful consideration of all factors affecting heat exchange in the working space of the furnace is required.

Chamber furnaces are used for both heating and heat treatment of ingots, slabs, pipes, finished products of large mass and complex configuration. Typically, the furnaces are large, and the articles therein are loaded in bags or stacks. Most often, they heat metal supplied in small batches that differ in size and heating or heat treatment modes.

The advantage of chamber furnaces is their versatility, that is, the ability to load various products into them each time, including inconvenient ones for transportation in continuous furnaces, and to vary the heating or heat treatment modes in a wide range .

The heating system of the chamber furnaces is designed to create maximum uniformity of temperatures in the working space of the furnace, therefore it is made dispersed .

Normalization (normalization annealing) is a type of heat treatment consisting in heating to a certain temperature, holding and subsequent cooling. This type is mainly used in heat treatment of steel. It is also used in the heat treatment of cast iron, copper alloys and some other alloys.

The purpose of this course project is to perform the thermal design calculation of the thermal furnace for the heat treatment operation - normalization (900℃).

Conclusion

The purpose of this course project was to carry out the thermal design calculation of the thermal furnace for the heat treatment operation - annealing (900℃).

The temperature plot, first drawn in the first approximation, is then specified, and its parameters can serve as the basis for calculating the duration of the metal in the furnace. The refinement of the temperature schedule consists in its correction according to the data of full-scale measurements of temperatures in the reference sections of the furnace zones, effective values ​ ​ of heat transfer coefficients, as well as a number of other changes.

Since the ratio > tg1 is satisfied, heating of the fuel is not necessary, and, therefore, we are limited only to heating of the oxidizing air. The temperatures of the combustion products for further calculations are taken according to the temperature schedule.

The following workspace profiling results were obtained during the calculation:

- length of the zone (of the whole furnace) L = 3.85 m;

- furnace width B = 2.3 m;

- furnace height H = 0.956 m.

By substituting the incoming and outgoing items in the heat balance equation for the first zone, fuel consumption was found:

According to the assignment, gas-oil burners of KGMGA type are installed in the furnace. Burners of the same type are selected for the entire furnace, and for the temperature zone - one type. Based on the air flow rate and pressure, the gas-gas burner KGMGA1 was selected.

By comparing the actual coolant velocities obtained as a result of the calculation with those previously accepted, it can be concluded that one recuperator is needed.

Figure 7.1. one furnace zone control units are presented:

1. temperature control unit;

2. fuel-to-air ratio unit;

3. furnace medium pressure control unit.

This scheme applies to each furnace zone individually.

The process efficiency of the furnace in question was 29.83%.