OPERATING FURNACES ON DRY BLAST

Dried blast, or dry blast, as it is commonly known, is the practice of controlling, at a predetermined point or level, the water vapour content of air which serves a blast furnace or cupola. It means reducing the water vapour content in summer months, but may include the reverse, that is, raising the water vapour content of the blast, during the winter months, up to that same predetermined level. From another angle, it is the practice of eliminating, from furnace operation, throughout the 12 months, both the fast moving and long-term variables which otherwise are introduced by variations in weather. The main advantage of such a process is control of furnace temperature which is made possible by the fact that part of the water vapour is broken down into hydrogen and oxygen, and that the heat of dissociation is absorbed in the melting zone.

Fundamentally, dry blast is a tool for eliminating one of the variables in blast furnace operation and can be made to serve two different purposes: to drive for maximum production and to secure fuel economy, smoothness of operation, uniformity of product, and low cost.

It gives five major advantages:

1. The operation of other equipment is simplified by its feeding air to the blowers at a constant temperature and a constant humidity. With that type of plant, there is no need of continually, hour by hour, readjusting blower speed to make it supply the blast furnace with a constant weight of oxygen.

2. The cost of maintenance is reduced by feeding clean air to the blowers.

3. With respect to increased production, constant humidity permits driving the furnace safely up to the limit of other variables or factors. Sudden changes in humidity cause sudden changes in the temperature of critical furnace zones. Without dry blast, there must be held a reserve for meeting sudden changes in humidity. But when this danger is eliminated, all this reserve can be safely applied to the production of more tonnage.

4. With respect to fuel economy it is known that, as the humidity of furnace blast increases, more carbon must be burned to produce a ton of iron.

5. With respect to a more uniform product, regularity and smoothness of operation reduce off-grades both as to specification and temperature. In the case of mill iron, the advantages of uniformity extend on through the Bessemer and the open-hearth. In the case of foundry iron, the furnace can be changed quickly and with certainty from one specification to another, it can reduce off-grade product and supply iron of more precise specifications.

TOPIC: «MY SPECIALITY IS FOUNDRY»

I am a second-year student. I study at the Technical University, in the machine-building faculty, its foundry department. I want to be a foundry engineer. We study the following special subjects: technology of foundry, physical fundamentals of metallurgy, theory of foundry processes, equipment of foundry shops and others. At the same time we get practice in the laboratories. In laboratories we try our theoretical knowledge and study the main technological processes.

After the graduation from the University we shall become foundry engineers. This speciality is the most important one in machine-building and metalworking. Most of all machine parts are cast. All the products made of metal begin their life in a foundry.

The process of producing castings may be divided into three stages: making a mold, melting metal, making casting and their finishing. The process of making molds is the most complex one and it consists of making a pattern, preparing molding materials, making and assembling molds, making and drying cores and molds. Foundries work with a large number of ferrous and non-ferrous metals. The foundries mix the relatively pure metals to produce the desired alloy. For producing castings foundry-men apply various methods. The oldest method is making sand castings in the foundry. These molds are used only once and each casting requires a new mold. There are some other casting processes such as die-casting, centrifugal casting, investment casting, and vacuum casting which are also very important in the foundry practice.

Abbreviations

amps – amperes – ампер

C/ Cent – Centigrade – шкала Цельсия

Co – Company – компания

deg – degree – градус, степень

dia – 1) diameter – диаметр, 2) diagram – диаграмма

dprt – department – отдел, отделение, участок

etc – et cetera/ and so on – и так далее

F – Fahrenheit – шкала Фаренгейта

fce – furnace – печь

Fig. – figure – рисунок, чертёж

ft – foot (feet) – фут (футы) = 30,5 см.

fph – feet per hour – футов в час

fpm – feet per minute – футов в минуту

fps – feet per second – футов в секунду

HP/ hp – horse power – лошадиная сила

hr – hour – час

in – inch – дюйм = 25,4 мм.

kw – kilowatt – киловатт

lb – libra, pound – фунт = 453,6 г.

No – number- номер

oz – ounce – унция = 28, 35 г.

p.c. – per cent – процент

viz – videlicet – то есть, а именно

vs – versus – против

yd – yard –ярд = 91,44 см.

yr – year – год

z – zero – нуль

Bibliography

1. Агабекян И.П., Коваленко П.И. Английский для технических вузов.– Серия «Высшее образование».- Ростов н/Д: «Феникс», 2004.– 352 с.

2. Балабан М.А. Английский язык для учащихся вузов по специальности «Машиностроение». – М.: УРАО, 1991.– 225 с.

3. Бгашев В.Н. Английский язык для машиностроительных специальностей.– М.: Высш. шк., 1990.– 416 с.

4. Комиссаров В.Н., Кораллова А.Л. Практикум по переводу с английского языка на русский.- М.: Высш. шк., 1991.– 320 с.

Contents

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