Air Blast System for Blast Furnace Jan29

Air Blast System for Blast Furnace...

Air Blast System for Blast Furnace A blast furnace (BF) produces liquid iron (hot metal) by the reduction of ore burden with reducing gases. The reducing gases are produced by the reaction of oxygen with coke and coal. This oxygen is part of enriched hot air blast which is blown and distributed at the bottom of the BF through the straight pipes, blowpipes and the tuyeres. This set is connected to the main bustle pipe. The volume of air which is enriched with oxygen and blown for the process in the BF to take place is provided by the air blowers. These air blowers take the air from atmosphere and compress it to the required pressure. This compressed air which is at about up to 200 deg C temperatures after compression is enriched with oxygen and blown into the hot stoves where the temperature is raised up to 1.200 to 1250 deg C. This hot blast air is then taken to bustle pipe through hot blast main. Air blast systems of modern high capacity blast furnaces operate with blast temperatures of up to 1350 deg C and blast pressures up to 5 kg/sq cm (g). The whole process is typically shown in Fig 1. Fig 1 Schematics of typical air blast system The main components of an air blast system of a blast furnace consist of (i) air blower, (ii) cold blast main, (iii) hot blast stove along with its combustion system, (iv) hot blast main, (v) bustle pipe, (vi) blow pipes and tuyeres known as tuyere stocks, (vii) set of valves, and (viii) control instruments. The air blower is the first equipment in the air blast system. It is located in the blower house and is meant for providing cold air blast to the...

Improved Designs  and Campaign Life of a Blast Furnace May23

Improved Designs and Campaign Life of a Blast Furnace...

Improved Designs  and Campaign Life of a Blast Furnace The cost of rebuilding or relining a blast furnace (BF) is very high. Hence techniques to extend BF campaign lives are important and need to be pursued very actively. Large BFs usually have a slightly higher campaign output per unit volume. This difference is because larger BFs generally are of more modern design and are well automated.  Since the viability of an integrated steel plant depends on a continuous supply of hot metal (HM), which, in a plant with a small number of large BFs, puts great importance on long campaign life. The techniques for prolongation of BF campaign life falls under the following three categories. Operational practices – The control of the BF process has a major effect on the campaign life. BF is to be operated not only for meeting the production needs but also to maximize its life. Hence it is necessary to modify operating practices as the campaign progresses and in response to the problem areas for the maximization of campaign life. Remedial measures – Once wear or damage that affects the life of the BF becomes evident, engineering repair techniques are to be used or developed to maximize campaign life. Improved designs – As improved materials and equipment are developed, these are to be incorporated into future rebuilds to extend the life of critical areas of the BF, where it is cost effective to do so. Improved designs of the BF for improving the campaign life are discussed in this article. The correct design of the furnace proper is fundamental to reliable operation, metallurgical performance, sustained high productivity, long campaign life and an availability of more than 98 %. BF design has had many improvements in recent decades and campaigns...

Coke Oven Gas Injection in a Blast Furnace Jul19

Coke Oven Gas Injection in a Blast Furnace...

Coke Oven Gas Injection in a Blast Furnace  The iron and steel industry is one of the main consumer of energy and hence responsible for high emissions of carbon di oxide (CO2). Despite remarkable decrease in specific CO2 emissions by most of the steel plants, the total amount of CO2 emissions is growing across worldwide due to the continuous increasing of steel production which has reached to a level of 1606 million tons in 2013. Nowadays the steel industry is facing an increasing demand to minimize the energy consumption and gas emissions especially from ironmaking processes. The efficient use of byproduct gases is essentially important for the profitability of steel plant operation due to the high energy volumes and the costs involved. The injection of coke oven gas (COG) into the modern blast furnace is one of effective measures for steel industry to achieve low carbon ironmaking, energy saving and emission reduction. Coke is an essential input to the iron making process and is produced by heating coal in coke ovens. To make coke, coal is heated in the absence of oxygen to drive volatile matter from it. COG is produced as a byproduct of the process in case of byproduct coke oven batteries normally installed in steel plants. The specific amount of COG generated during coke making in the byproduct coke ovens is in the range from 290 to 340 N cum/t of coal charge depending on the volatile matters in the coal charge. The COG is currently used after its cleaning from tar, naphthalene, raw benzene, ammonia, and sulfur for heating of blast furnace stoves, ignition furnaces in sintering plant, heating furnace in rolling mills and electric power generation in power plant. The COG has a composition which consists of around 55...

Pulverized coal injection in a blast furnace May10

Pulverized coal injection in a blast furnace...

Pulverized coal injection in a blast furnace Pulverized Coal Injection (PCI) is a process that involves injecting large volumes of fine coal particles into the raceway of a blast furnace (BF). This provides not only a supplemental carbon source but also speeds up the production of liquid iron besides reducing the need for metallurgical coke for reactions in the blast furnace. The desire to move away from the production of the metallurgical coke with its inherent environmental problems has motivated the use of pulverized coal injection in blast furnace. History Pulverized coal injection was developed in 19th century, but was not implemented for industrial use. In early sixties of the last century PCI was successfully implemented in AK Steel of USA and Shougang in China. Though trials in several countries at that time had proved that the technology for pneumatic transport and injection of coal were available, but the economics and relative ease of the process was such that oil and natural gas injection became more popular. During energy crises of seventies people started showing interest in the process of PCI. This process developed very fast during 1980s and in the second half of the 1980s there were successful practices of coal injections at rates ranging from 180 Kg/tHM to 200 Kg/tHM. In nineties PCI technologies became mature. But the real shift to PCI has taken place only when the cost of metallurgical coke started rising due to the increased global demand. Concept and the process of coal injection The PCI technology is based on the simple concept of carrying the finely ground (pulverized) dried coal by a conveying gas (normally nitrogen) to the blast furnace where it is distributed to different tuyeres and injected through a lance in the blow pipe. In the...