Pulverized coal injection method

Background

Iron is a most fundamental metal used for a life of human being, as it is rich in resource resulting in low price, can easily be extracted, and easily modified due to its useful material property. After an industrial revolution (18-19th century), iron becomes a core material of industrial market, its importance was referred to “iron is nation”, its productivity was directly treated as its national power. Therefore after the World War 2, government vigorously supported the growth of iron industrial market; as a consequence, the action significantly contributed and influenced the development of global economy. For the various application uses, iron ore is extracted and smelted through a uses of metallurgical furnace called "Blast Furnace".

Blast furnace is considered to survive for another century because of its highly efficient iron production rate at competitive costs with other iron making technology. Blast furnace efficiency keep on improving by adapting with new technological support which is stimulated from the accumulated global demand, yet the main chemical process remains same. Although improvement of process does not mean solving for the problem associated in uses of blast furnace. Iron production rate is highly influenced from world economics which varies over the time and improvement of operation efficiency can be considered as one of major concerns from uses of blast furnace, however biggest drawback of blast furnace operation is its inevitable carbon dioxide production from iron reduction processes, which is considered as major contributor in global warming. Nowadays, Pulverized Coal Injection (PCI) method is internationally popular method in improving blast furnace operation.

Pulverized Coal Injection method

Pulverized coal injection (PCI) method was developed in 19th century, but this method was not implemented till the 1970s. Rise in concerns due to increased coke cost due to competition from accumulated demand for iron production and limiting resources, this method was attractive to iron making industries and increased its value.

PCI method is based on the simple concept of primary air (termed as conveying gas) carrying pulverized coal through a lance to the tuyere (mid bottom side inlet of blast furnace), then mixed with secondary hot air (termed as blast) supplied through a blowpipe in tuyere then piped to a furnace to create a balloon like cavity called a “raceway”, which then propagates coal, coke combustions and melts solid iron ore and reduces it to molten iron. The most remarkable property of this method was that this method allows for cheaper coal to be consumed in the system to replace expensive coke; as a result, it can remarkably cut down on costs. Due to severe environment inside the furnace, (>2000K), visual observations of raceway shape and size is impossible, therefore sensors regestering numbers are preferred to investigate the chemical and physical reactions inside the furnace.

Better understanding of the raceway and PCI method can optimize the performance of a blast furnace and reduce its cost. In recent years, further improvement of PCI method and the use of coal blend (mixing multiple different coals) injection methods are attracting industry.