Abstract

Content

• Introduction
• 1. Relevance
• 2. Purpose and research problems
• 3. Review of researches and developments
• Conclusions
• List of sources

Introduction

PJSC "Donetskstal" - steel works" - the modern enterprise of ferrous metallurgy of Ukraine which main activity is - modernization of production and introduction of new technologies, the solution of environmental issues, expansion of a range and release of high-quality competitive production.

1. Relevance

For the last five-seven years in world economy consumption of the steel products which are especially made by melkosortny camps of steel works was sharply reduced. On world roar demand for such types of rolling production as corners of the different sizes, a channel, circles, squares, hexagons and other types, that is almost most part of production demanded earlier has also fallen, in particular it has affected structure of the orders received in 2012-2014 by the Donetsk steel works on high-quality hire. The volume of big orders by all types of a rolling row was sharply reduced.

The compelled idle times of the heating furnace, so and rolling mill can reach up to 40% of calendar time a year with average duration of idle time up to 5 days. The methodical heating furnace operated on DMZ for heating of square preparations under rolling on a camp 400 unlike modern furnaces differs in the increased thermal losses.

2. Purpose and research problems

- development of a method of calculation of thermal losses;

- decrease in thermal losses through lining of the furnace;

- decrease in costs of fuel of a furnace conclusion in an operating mode.

3. Review of researches and developments

In our work we suggest to cover an internal surface of the furnace (the arch and walls) with insulating plates with low coefficient of heat conductivity.

Internal surface isolated by modern materials from ceramic fibers has a number of advantages before a shamotny brick:

- low heat accumulation during heating;

- the virtual absence of repairs, cost savings;

- rapid heating and cooling, increased productivity;

- lifetime keramovoloknistyh blocks of at least 20 years.

Such way of isolation is applied in the forge, thermal and other furnaces working in the periodic thermal mode and temperature level in them doesn't differ from conditions of heating of metal in the methodical furnace. Operating experience of such furnaces in forge shops has allowed to reduce sharply losses of heat by a warming up of a fire-resistant laying in intervals between technological breaks and to cut fuel consumption.

Figure 1 – Internal isolation in furnaces of the periodic thermal mode

Operation of the heating furnace in the heating cooling mode has demanded to define the most rational and economic way of reduction of thermal losses in working space. This task can be solved as with use of a method of mathematical modeling and expeditious diagnostics on the basis of the analysis of instant thermal balances [1, 2], and by means of engineering techniques. In this work the simplified engineering method of calculation of heat content of lining at the compelled idle time of the furnace is created. For such furnaces of loss of heat about three essentially various directions are formed: through a fire-resistant laying, on heating of the atmospheric air coming to working space through a thinness of constructive elements and a fire-resistant laying, cooling the glissazhnykh of pipes in welding and methodical zones of the furnace.

In this work dynamics of cooling of working space of the furnace in various zones at idle time allowing to define a thermal condition of each zone for various intervals of an idle time of the furnace was investigated. On the basis of laws of heat exchange and taking into account experimental data the method of calculation of thermal losses is made and the program allowing to determine temperature of an internal surface of a laying of the furnace and the residual accumulated heat on any time interval of cooling of the furnace is developed.

Method of calculation of thermal losses

1. Definition of an initial thermal stream

2. Determination of temperatures on borders of layers

3. Determination of size of accumulation of each layer

4. Definition of the general heat of accumulation of a laying of the furnace at the beginning of the I interval of time

5. Definition of losses of heat through a furnace laying

6. Definition of losses of heat on heating of the atmospheric air coming to working space of the furnace

7. Definition of losses of heat through glissazhny pipes

8. Definition of losses of heat for one elementary time interval of cooling of a separate zone or all furnace

9. Definition of the remained accumulated heat in a laying after one interval of cooling

10. Definition of the remained accumulated heat in the first layer

11. Determination of srednemassovy temperature of the first layer after one interval of cooling

12. Determination of temperature of an internal surface of the first layer after one time interval of cooling

13. Definition of a thermal stream through a multilayered laying at a temperature of a surface of the first layer

14. The received thermal stream is the beginning of calculation of the following interval of cooling of the furnace

Conclusions

The developed technique will allow with a sufficient accuracy to predict a thermal condition of lining of the furnace after idle times of any duration. This information is necessary for determination of rational technological parameters on a furnace conclusion in a working thermal condition.

At the moment writing of this paper the master's thesis isn't finished yet. Final conclusion May, 2017. The full text of work and materials on a subject can be provided by the author or his head after the specified date.

List of sources

1. Бирюков А.Б. Диагностика нагревательных печей периодического действия на основании построения и анализа моментальных тепловых балансов / А.Б. Бирюков, Е.В. Новикова, Т.Г. Олешкевич // Промышленная теплотехника. - 2014. - T.36 №2. - С. 29.
2. Современные подходы к диагностике процессов тепловой обработки металла в печах / А.Б. Бирюков, С.М. Сафьянц, А.А. Иванова, Е.Н. Андриенко // Черная металлургия. - 2015. - №1 (1381). - С. 50-55.