Process Steam and its use in a Steel Plant...

Process Steam and its use in a Steel Plant Process steam is the general term used for steam which is used in process applications such as a source of energy for process heating, process cooling, pressure control and mechanical drives among others. Process steam is a popular mode of conveying energy and may come into contact with the final process or product. Like compressed air, steam is often thought of as a utility which is often generated at a central location and then distributed to various points-of-use throughout the steel plant. At atmospheric pressure the saturation temperature is 100 deg C. However, if the pressure is increased, this allows the addition of more heat and an increase in temperature without a change of phase. Therefore, increasing the pressure effectively increases both the enthalpy of water, and the saturation temperature. Water and steam can coexist at any pressure, both being at the saturation temperature. Steam at a condition above the saturation condition is known as superheated steam. Temperature above saturation temperature is called the degree of superheat of the steam and water at a condition below the saturation condition is called sub-saturated water. Steam used as process steam is usually of the following types. (Fig 1) Saturated steam – Steam is said to be ‘saturated’ with energy at a given and constant pressure when the addition of more heat to the generation system results in more steam, but no rise in steam temperature. In this state, the steam cannot hold more heat energy in a given volume unless pressure is allowed to rise. Dry steam – It is the steam that contains 100 % of water vapour in the gas phase. Dry saturated steam – Achieving the above states of dry and saturated steam simultaneously...

CLU process for Stainless Steel Production Dec28

CLU process for Stainless Steel Production...

CLU process for Stainless Steel Production Stainless steel production process has some basic features such as carbon (C) removal, deoxidation and desulphurization. In the production process, these operations are generally combined with some alloying with solid material as well as nitrogen (N2) control.  These requirements are met in different ways in various processes being deployed for the production of stainless steel. The CLU process is similar to the AOD (argon oxygen decarburization) process for making stainless steels. CLU refers to the Creusot-Loire Uddeholm process for stainless steel production. It also uses liquid steel from an electric arc furnace (EAF) or any other similar primary steel making furnace.  The major impetus for the development of the CLU process was the idea to use superheated steam as the diluting gas instead of argon (Ar) gas which is used in the AOD process. Superheated steam has been used as a process gas in stainless steel production since the early 1970s when this technology was developed at Uddeholms Degerfors steel plant in Sweden. In France a similar development took place within the Creusot-Loire group. The developed process was named Creusot Loire Uddeholm (CLU) process. The converter originally used in CLU process was a bottom blown converter thus differentiating it from the side blown AOD converter. However, presently CLU process with the use of a side blown converter is also available. The first commercial plant using the CLU process was built in 1973 by Uddeholm. Between 1973 and 2003 stainless steel was produced in Uddeholms Degerfors steel plant in an 80 ton converter where superheated steam, Ar, N2, oxygen (O2) and compressed air were used as process gases. The converter in the Degerfors steel plant was operated for 30 years as a CLU process for stainless steel production before...

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...

Basics of Steam Boiler Feb22

Basics of Steam Boiler...

Basics of Steam Boiler A steam boiler is an enclosed container where water is heated under controlled conditions to convert it into steam. Boiler is basically a heat exchanger where heat is transferred to water. It is also sometimes referred to steam generator. Thermal energy for heating water is supplied either by fuel (Gas, liquid or solid) or by waste energy available from various industrial processes. Sometimes solar energy is also used for the production of steam. Steam produced in a boiler can be low pressure, medium pressure or high pressure.  In an industrial context, the steam produced is used as process steam in various industrial processes or for driving turbines for the production of electricity. Every boiler is designed to transfer as much thermal energy as possible to the water contained in the boiler. Heat energy is transferred by conduction, convection and radiation. The relative percentage of each is dependent upon the type of boiler, the designed heat transfer surface and the fuels that power the combustion. There are mainly two types of boilers. They are fire tube boiler and water tube boiler. Fire tube boiler consists of numbers of tubes through which hot gasses are passed. These hot gas tubes are immersed into water, in a closed vessel. In this boiler one closed vessel or shell contains water, through which hot gas tubes are passed. These hot gas tubes heat up the water and convert the water into steam and the steam remains in same vessel.  Fire tube boilers are generally used for relatively small steam capacities and low to medium steam pressures. These boilers are compact, of packaged construction and cheaper. Water tube boiler is a kind of boiler where the water is heated inside tubes and the hot gasses surround...