Factors affecting Lining Life of a Basic Oxygen Converter Sep20

Factors affecting Lining Life of a Basic Oxygen Converter...

Factors affecting Lining Life of a Basic Oxygen Converter The life, reliability and costs of lining in a basic oxygen converter are vital for the smooth operations of the steel melting shop utilizing basic oxygen process for steel production.  Higher lining life results into improved availability of the converter which in turn improves its productivity. Three important factors for achieving higher lining life of the basic oxygen converter (Fig 1) are (i) qualities of refractories and their laying pattern in the converter, (ii) operating practices followed, and (iii) monitoring of the lining wear and practices for the maintenance of the refractory lining. Development of improved refractory materials in combination with improved process control and better maintenance during campaigns make it possible to increase the lining life of the basic oxygen converter. Fig 1 Factors affecting lining life of the basic oxygen converter These days without exception, basic oxygen converters are lined with magnesia – carbon (MgO-C) refractories because of their superior properties than other types of converter lining materials. However zoned refractory lining practices are followed by using MgO-C refractories of different qualities in different areas of the converter. The causes of wear of refractories in the basic oxygen converter are either due to chemical reasons or due to the physical reasons. Chemical causes for the wear of the converter lining are mainly due to gaseous materials (oxidizing gases, reducing gases, and water vapour), liquid materials (slag. hot metal, and liquid steel melt), and solid materials (fluxes, and carbon disintegration).  Physical causes for the wear of the converter lining are excessive temperatures (poor dissipation, and hot spots), static mechanical stresses (spalling, and expansion), and dynamic mechanical stresses (abrasion, impact, and vibrations). The key wear mechanisms of the refractory lining of basic oxygen converter can...

Gears and their types...

Gears and their types Steel plant supplies material for the manufacture of gears and it uses gears of different types and sizes in the equipment and machineries deployed for the production of steel. Gears are the most common means used for power transmission. They are compact, positive-engagement, power transmission elements that determine the speed, torque, and direction of rotation of driven machine elements. They are widely used in various mechanisms and devices to transmit power and motion positively (without slip) between two shafts which are (i) parallel, (ii) collinear, (iii) perpendicular and intersecting, (iv) perpendicular and nonintersecting, and (v) inclined at any arbitrary angle. The power transmission can be (i) without change in the direction of rotation, (ii) with change in the direction of rotation, (iii) without change of speed (of rotation), and (iv) with change in speed at any desired ratio. Sometimes a gearing system (rack – and – pinion) is used to transform rotary motion into linear motion and vice-versa. Gear wheels have projections called teeth that are designed to intersect the teeth of another gear. When gear teeth fit together or interlock in this manner they are said to be in mesh. Gears in mesh are capable of transmitting force and motion alternately from one gear to another. The gear transmitting the force or motion is called the drive gear and the gear connected to the drive gear is called the driven gear. Basically gears are wheels having, on its periphery, equispaced teeth which are so designed that those wheels transmit, without slip, rotary motion smoothly and uniformly with minimum friction and wear at the mating tooth profiles. For the achievement of such favourable conditions, maximum numbers of gears have their tooth form based on involute curve. Involute curve is simply...

Hazard and Risk Management in a Steel Plant...

Hazard and Risk Management in a Steel Plant Hazard is a source or situation that has the potential for harm in terms of human injury, ill health, damage to property or the environment, or a combination of these factors. It has got a short or a long term effect on the work environment with considerable human and economic costs. It has also got a great demoralizing effect on the workforce. A hazard can have a potential to create an emergency like situation at the work place. Hazard is defined as “a condition, an event, or a circumstance that can lead to or contribute to an unplanned or undesirable event”. Hazard is a potential cause to generate a disaster. It has got the potential to cause (i) serious harm to the individual or the environment, (ii) harm, the severity of which depends on the extent and frequency of exposure to the hazard, and (iii) harm that does not usually occur, or is not usually detectable until a significant time (years) after exposure to the known hazard. Any activity, procedure, plant, process, substance, situation or other circumstance that has the potential to cause harm constitutes a hazard. Hazards exist in every workplace in different forms and required to be identified, assessed and controlled regarding the work processes, plant or substances. They arise from (i) workplace environment, (ii) use of plant and equipment (steel plant processes), (iii) use of substances and materials, (iv) poor work and/or plant design, (v) inappropriate management systems and work procedures, and (vi) human behaviour. Types of hazards include the following. Physical – These hazards are due to noise, vibration, lighting, electrical, heat, cold, dust, fire, explosion, moving parts, and workspace etc. Ergonomic – These hazards are due to tool design, equipment design, job...

Blowing of Oxygen in Converter Steelmaking Sep14

Blowing of Oxygen in Converter Steelmaking...

 Blowing of Oxygen in Converter Steelmaking Oxygen (O2) is blown on the hot metal in the converter during steel making for removal of impurities such as carbon (C), silicon (Si), manganese (Mn), and phosphorus (P) etc.  A water cooled lance is used to inject oxygen at very high velocities onto a liquid bath to produce steel. In the 1950s when the top blown converter process was commercialized and the size of the converter was limited to 50 tons maximum then a lance with a single hole lance tip was being used for the blowing of O2 in the converter. With the passage of time the converter size went on increasing. This has necessitated increase of number of holes in the lance tip for better distribution of O2 over a larger surface of the bath in the converter. With the increasing demands to produce higher quality steels with lower impurity levels, O2 of very high purity is required for steelmaking in the converter. The O2 needed for steelmaking is to be at least 99.5 % pure, and ideally 99.7 % to 99.8 % pure. The remaining parts are 0.005 % to 0.01 % nitrogen (N2) and the rest is argon (Ar). In top-blown converters, the O2 is jetted at supersonic velocities with convergent divergent nozzles at the tip of the water cooled lance. A forceful gas jet penetrates the slag and impinges onto the surface of the liquid bath to refine the steel. Today most of the converters operate with lance tips containing 3 to 6 nozzles. Even 8 nozzles lance tips are under use. The axes of each of the nozzles in a lance with a multi hole lance tip are inclined with respect to the lance axes and equally spaced around the tip....

Couplings and Their Types...

Couplings and Their Types In all areas of a steel plant, there is a necessity for the reliability and high performance of machinery and equipment.  Couplings, serving as vital transmission parts, are no exception to meet higher and more stringent quality requirements needed for the steel plant’s equipment and machinery. In the simplest of terms, a coupling’s purpose is to transfer rotational movement from one shaft to another. Couplings are used to connect two shafts for torque transmission in varied applications. It may be to connect two units such as a motor and a generator or it may be to form a long line shaft by connecting shafts of standard lengths say 6 m to 8 m by couplings. In addition, couplings are capable of transmitting axial thrust loads between machines and any axial growth that may occur due to high temperature. Couplings may be rigid or they may provide flexibility and compensate for misalignment. They may also reduce shock loading and vibration. A wide variety of commercial shaft couplings are available ranging from a simple keyed coupling to one which requires a complex design procedure using gears or fluid drives etc. However there are two main types of couplings (Fig 1) which are (i) rigid couplings, and (ii) flexible couplings. Fig 1 Types of couplings Rigid couplings Rigid couplings are used for shafts having no misalignment. Since these couplings cannot absorb any misalignment the shafts to be connected by a rigid coupling must have good lateral and angular alignment. As compared with flexible couplings, rigid couplings have limited application. Rigid couplings do not have the ability to compensate for shaft misalignments and are therefore used where shafts are already positioned in precise lateral and angular alignment. Any misalignment between shafts will create high...