Annealing of Steels

Annealing of Steels Annealing is a process of heat treatment that alters the properties of steel to increase its ductility and to make it more workable. It involves heating the steel to slightly above its critical temperature, soaking at that temperature for a time sufficient to allow the necessary changes to occur and then cooling at a predetermined rate (Fig 1) Fig 1 Heating range of different annealing processes There are two main reasons for annealing. The first is to soften the steel material and remove the stresses. The second is to homogenize the structure of the steel material. By the process of annealing the properties of steel material are enhanced to meet machinability requirements. Annealing process induces ductility, improves toughness, softens the steel, relieves internal stresses, refines the structure by making it homogeneous, and improves cold working properties. Annealing also prepares the steel for further heat treatment. Theory of annealing process Annealing occurs by the diffusion of atoms within the steel material, so that the steel material progresses towards its equilibrium state. Heat increases the rate of diffusion by providing the energy needed to break bonds. The movement of atoms has the effect of redistributing and destroying the dislocations in the steel material. This alteration in dislocations allows steel material to deform more easily, so increases its ductility.] The amount of process initiating Gibbs free energy in a deformed steel material is also reduced by the annealing process. This reduction of Gibbs free energy is termed also as stress relief. The relief of internal stresses is a thermodynamically spontaneous process. However, at room temperatures, it is a very slow process. The high temperature at which annealing occurs serve to accelerate this process. The reaction that facilitates returning the cold worked steel material to its stress free state has many reaction pathways, mostly involving the elimination of lattice vacancy gradients...

Computerized Maintenance Management System...

Computerized Maintenance Management System Computerized Maintenance Management System (CMMS) is a computerized data base designed to optimize the management of maintenance activities in an organization. It is an orderly and systematic approach to planning, organizing, monitoring and evaluating maintenance activities and their costs. It is a management tool for planning and budgeting of equipment maintenance (routine, break down, preventive and predictive), capital repairs and equipment replacement activities. A good CMMS coupled with knowledgeable and capable maintenance work force can prevent problems related to equipment health, safety and environment deterioration. It CMMS also ensures that the organization maximizes the available maintenance resources it has at a plant, minimizes the operational downtime of its equipment, reduces the overall maintenance costs within the organization, improves the quality of the management decisions, helps in the verification of the regulatory compliance, and extends the life of the equipment at the plant. It also contributes into lowering of capital costs and improvement in quality of life. CMMS automates most of the functions performed by the maintenance personnel in an organization and hence improve their effectiveness. The main component of a CMMS is shown in Fig 1. Fig 1 Main components of a CMMS Objectives of CMMS The primary objectives of a CMMS are as follows. • To optimize the use of available funds, personnel, facilities and equipment through effective maintenance management methods. • To monitor the equipment conditions. • To provide accurate data for decision making regarding maintenance activities. • To identify systematically maintenance needs and equipment deficiencies as well as needs for capital repairs. • To determine the maintenance backlog and made provision for this maintenance. • To determine the maintenance priorities and plan accordingly • To enable preparation of maintenance budget using systematic standardized procedures. • To monitor...

Steam Turbine and Power Generation Feb28

Steam Turbine and Power Generation...

Steam Turbine and Power Generation A steam turbine is a mechanical device that converts thermal energy of the pressurized steam into useful mechanical work. It is the heart of a power plant. It has a higher thermodynamic efficiency and a lower power-to-weight ratio. It derives most of its thermodynamic efficiency because of the use of multiple stages in the expansion of the steam which results in a closer approach to the ideal reversible process. Steam turbines are one of the most versatile and oldest prime mover technologies being used to drive a generator. Power generation using steam turbines has been in use for more than 100 years. A turbo generator is the combination of a turbine directly connected to a generator for the generation of electrical power. Large steam power generators provide the majority of the electric power. Steam turbines are ideal for very large power configurations used in power plants because of their higher efficiencies and lower costs. In a power plant, the steam turbine is attached to a generator to produce electrical power. The turbine acts as the more mechanical side of the system by providing the rotary motion for the generator, while the generator acts as the electrical side by employing the laws of electricity and magnetism to produce electrical power. In a steam turbine rotor is the spinning component that has wheels and blades attached to it. The blade is the component that extracts energy from the steam. A typical schematic diagram of afossil fuel powered steam turbine based  power plant for electricity generation is given in Fig 1  Fig 1 Schematic diagram for steam turbine based power generation The energy conversion process Steam has the following three components of energy components Kinetic energy –  by virtue of its velocity Pressure energy...

Terms used related to Steam...

Terms used related to Steam The terms used related to steam are given below. Absolute pressure – It is gauge pressure plus atmospheric pressure. Atmospheric pressure – It is the normal pressure of the atmosphere on the sea level at 0 deg C. Boiling point – It is the temperature (100 deg C) at which water boils. Water boils when its absolute pressure reaches the vapour pressure. Condensation – It is defined as the change in the physical state of water vapour to liquid water. It is reverse of vaporization. Condensate – It is the liquid phase produced by the condensation of steam. Density of steam – It is the mass of steam per unit of volume of steam at the given pressure and temperature. It is the reciprocal of the specific volume. Dry saturated steam – On heating the wet steam, the water particles, which are in suspension, starts evaporating gradually and at a particular moment the final particles just evaporates. The steam at that moment is called dry steam or dry saturated steam. The resulting volume is known as specific volume of dry steam. This steam does not obey the gas laws. Dryness fraction of saturated steam – It is a measure of quality of wet steam. It is the ratio of the mass of dry steam to the mass of total wet steam. Enthalpy – Enthalpy of a system is defined as the mass of the system (m) multiplied by the specific enthalpy (h) of the system and can be expressed as H = m h, where H is enthalpy in kJ, m is mass in kg, and h is specific enthalpy in kJ/kg. Enthalpy is the total amount of heat received by 1 kg of water from O deg C at constant pressure to convert it to...

Supply Chain Management...

Supply Chain Management Supply chain is a network of facilities and distribution options that performs the functions of procurement of materials, transformation of these materials into intermediate and finished products, and the distribution of these finished products to customers. Supply chain management (SCM) is the management of the flow of materials, equipment, finances, information, and manpower resources within and among organizations to ensure the efficient and fast delivery of quality goods and services to the customer. It is the design, planning, execution, control, and monitoring of supply chain activities with the objective of creating net value, building a competitive infrastructure, leveraging logistics, synchronizing supply with demand and measuring performance. It is the conscious effort of an organization towards active management of supply chain activities to maximize customer value and achieve a sustainable competitive advantage. Different definitions of supply chain management which are commonly being used are given below. Supply chain strategies require a total systems view of the links in the chain that work together efficiently to create customer satisfaction at the end point of delivery to the consumer. As a consequence, costs get` lowered throughout the chain by driving out unnecessary expenses, movements, and handling. The main focus is turned to efficiency and added value or to the end user’s perception of value. Through the supply chain strategies efficiency is increased and bottlenecks are removed. The measurement of performance focuses on total system efficiency and the equitable monetary reward distribution to everyone within the supply chain. The supply chain system has to be responsive to customer requirements. The integration of key business processes across the supply chain for the purpose of creating value for customers and stakeholders. The management of upstream and downstream value added flows of materials, final goods, and related information among suppliers, organization, sellers,...