Remedial measures and Campaign Life of a Blast Furnace May17

Remedial measures and Campaign Life of a Blast Furnace...

Remedial measures 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. Remedial measures for improving the campaign life of the BF are discussed in this article. The measures which are normally adopted for improving the campaign life of BF are described below. Cold repairs and gunniting repair The stack refractory brick work is usually exposed to mechanical wear in the upper part and also to...

Acetylene Gas- its Characteristics and Safety Requirements...

Acetylene Gas- its Characteristics and Safety Requirements Acetylene is  a gas used in steel plants for oxy-acetylene gas cutting and welding and also in flame cutting machines of continuous casting machines. It is sometimes used for carburization of steel, flame heating, flame gouging, flame hardening, flame cleaning, flame straightening, thermal spraying, spot-heating, brazing, texturing and profile-cutting, and carbon coating. Acetylene is the chemical compound with the formula C2H2. It is an unsaturated hydrocarbon and the simplest alkyne. An acetylene molecule is composed of two carbon atoms and two hydrogen atoms. The two carbon atoms are held together by what is known as a triple carbon bond having CH bond angle of 180 deg. This bond is useful in that it stores substantial energy that can be released as heat during combustion. However, the triple carbon bond is unstable, making acetylene gas very sensitive to conditions such as excess pressure, excess temperature, static electricity, or mechanical shock. Acetylene is a flammable and colourless gas. Its molar mass is 26.04 g/mol. It is unstable in pure form and thus is usually handled as a solution. Pure acetylene is odourless, but commercial grades usually have a marked garlic like odour due to impurities. It has a density of 1.11 kg/cum at 1 atmosphere pressure and 15 deg C. The specific gravity is 0.91 (air=1).  It is lighter than air so does not accumulate at low levels, where it could cause a potential hazard. The boiling point of gas is – 84.7 deg C and melting point is -80.75 deg C. The adiabatic flame temperature (AFT) in air at atmospheric pressure is 2534 deg C. The auto ignition temperature of acetylene gas is 305 deg C.  Its lower and upper explosive limits in air under STP conditions (0 deg C and 1.02 kg/sq cm) are 2.4 volume...

Safe Working Procedures and Safe Work Practices...

Safe Working Procedures and Safe Work Practices For the implementation of the safety management system, the organization is to establish safe working procedures and safe work practices so that all the works are carried out safely and the risks of injury to work men and damage of equipment and property are eliminated or minimized. The safe working procedures and safe work practices are to be established meeting the requirements of the Factories Act as well as meeting the requirements of the work processes. Safe working procedures and safe work practices are established in the organization for addressing significant hazards or for dealing with circumstances that may present other significant risks/liabilities for the organization. They reflect the approach of the organization for controlling safety hazards. Safe working procedure is a step by step process that guides a work man through a task from start to finish in a chronological order. Safe work procedures are designed to reduce the risk by minimizing potential exposure for performing a work safely from beginning to end. Safe work practice is a set of guidelines established to help work men to perform a task which may not require a step by step procedure.  Safe work practices are generally written methods outlining how to perform a task with minimum risk to people, equipment, materials, environment, and processes. Safe working procedures and safe work practices tells work men  how to perform a specific task so as to mitigate hazards that have been identified through the hazard identification process. They are guideline documents for the maintenance of safety in the organization. The extent of the application of the safe working procedures and safe work practices depends on the safety policy of the organization, the nature of the activities in the organization, and complexity of...

Operation practices and Campaign Life of a Blast Furnace May11

Operation practices and Campaign Life of a Blast Furnace...

Operation practices 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 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 furnaces puts great importance on long campaign life. The techniques for prolongation of BF campaign life (Fig 1) 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 actions – 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.   Fig 1 Techniques for prolongation of blast furnace campaign life Operational practices for improved campaign life are discussed in this article. The operating practices affecting the BF campaign life are described below. Productivity The productivity of a BF is normally expressed in tons (t) of HM per unit BF volume (cum) per...

Converter Gas, its Characteristics and Safety Requirements...

Converter Gas, its Characteristics and Safety Requirements During the process of steel making in the basic oxygen furnace (BOF), significant amount of gases, rich in carbon monoxide content, are generated during the blow time at a temperature of 950 deg C. This gas is termed as converter gas or BOF gas. Converter gas is also known as LD gas. It is a byproduct gas produced during the production of liquid steel in a basic oxygen furnace (converter), where impurities of hot metal are oxidized with oxygen gas. The main constituents of converter gas are carbon mono oxide (CO), carbon di oxide (CO2), oxygen (O2) and nitrogen (N2).  Composition wise it is similar to blast furnace gas but with lesser percentage of nitrogen in it. Converter gas is dust laden at the converter mouth. The dust content is around 100 to 120 g/N cum. The recovered converter gas is cleaned in a venturi scrubber using water, followed by processing in the mist eliminators. The gas is then stored in gas holder for steady supply and cleaned further in the electrostatic precipitators (ESP) and finally fed to the gas distribution system. Wet type of gas cleaning plants have capabilities to reduce the dust content of the gas to a level of 5 mg/N cum. The composition of the gas varies from start to the end of the blow and this is a function of the blow time. In the oxygen rich phase (air ratio= 1) at the beginning and at the end of the blowing period the primary gas is burned completely and no gas is recovered during this period. During CO rich phase (air ratio less than 1) only partial oxidation takes place and a combustible waste gas is formed containing CO, H2, CO2 and...