Blast Furnace Gas Top Pressure Recovery Turbine Jun24

Blast Furnace Gas Top Pressure Recovery Turbine...

Blast Furnace Gas Top Pressure Recovery Turbine  Modern blast furnaces in steel plants operate at a high top gas pressure. The blast furnace (BF) gas leaving the BF at the top still maintain a pressure of around 1.6 kg/sq cm (g) to 3 kg/sq cm (g) and has a temperature of around 200 deg C.  This BF gas which is coming out at the top of a BF is cleaned to remove dust and the cleaned gas is used in the steel plant as a fuel for heating purpose at a relatively low pressure. In the process, a large amount of pressure energy is lost across the valve. BF gas top pressure recovery turbine (TRT) is a mechanism that utilizes the BF gas heat and pressure energy to drive a turbine.  The work generated by the turbine is transferred to a generator and converted to electric power. TRT generates power by exploiting a known property of all gases which is the expansion of gas volume with the reduction of its pressure. The system comprises dust collecting equipment, a gas turbine, and a generator. TRT is basically an energy saving measure at the BF which utilizes the waste pressure energy of the BF top gas to generate electric power. A TRT unit can produce around 15 to 60 kWh/t of hot metal (HM). Its output can meet around 30 % of the power needed by the all equipment (including the air blower) of the BF. The BF gas leaving the TRT unit can still be used as fuel in the steel plant. During iron making process, BF gas with high pressure and temperature is produced in blast furnace. In conventional practice, the energy of BF gas is wastage by pressure reduction at septum valve. Equipping TRT...

Complex Phase Steels

Complex Phase Steels  The complex phase (CP) steels belong to the group of advanced high strength steels (AHSS) grade, which gain their strength through extremely fine grain size and a micro structure containing martensite in small amounts, and pearlite embedded in the ferrite/bainite matrix. A very high grain refinement is achieved by precipitation of micro alloying elements such as niobium (Nb), or titanium (Ti), or retarded recrystallization. The advantage of the CP steels is that cold forming, without subsequent quenching and tempering, is possible, thus implying a considerable cost saving potential. CP steels are currently being produced as hot rolled steel strips as well as cold rolled advanced high strength steels, which are hot dip galvanized for corrosion protection. The chemical composition of CP steels, and also their microstructure, is very similar to that of TRIP steels, but, additionally it contains some quantities of Nb, Ti and or V (vanadium) to cause the precipitation strengthening effect. Typically, CP steels have no retained austenite in the microstructure, but contain more hard phases like martensite and bainite. The microstructure of CP steels is composed of a very fine ferrite with the high volume fraction of hard phase, For cold shaped products, a triple phase steel containing ferrite, bainite and martensite can be designed which are obviously more difficult to produce. The bainitic complex phase microstructure exhibits better strain hardening and strain capacity than that for fully bainitic micro structure. It involves a strength graded microstructure where the martensite and bainitic ferrite phases are separated by a third phase of intermediate strength. Fig 1 shows typical micro structure of CP steels. Fig 1 Typical micro structure of CP steels  Properties of CP steels The mechanical properties of CP steels are characterized by continuous yielding and high uniform...

Customer Satisfaction...

Customer Satisfaction  Customer is defined as one who receives the product or service which is provided by the organization and which has value. Customer satisfaction is a term which is frequently used in marketing. The term is the measure of the degree to which a product or service provided by the organization meets or exceeds the expectations of the customer. Customer satisfaction is defined as ‘the number of customers, or percentage of total customers, whose reported experience with the organization, its products, or its services (ratings) exceeds specified satisfaction goals’. Customer expectations are continuously increasing. Brand loyalty is a thing of the past. Customer seeks out products and organizations that are best able to satisfy his requirements. A product does not need to be rated highest by the customer on all dimensions, only on those he thinks are important. The customer is always right. The job of the organization is to provide the customer what he wants and when he wants it. Customer satisfaction is the perception of the customers that the organization has met or exceeded their expectations. Customer satisfaction is important since it provides the management of the organization with a metric that can be used to manage and improve the operations and the functioning of the organization. It is also essential for the organization so that it can achieve success in today’s competitive market place. An organization cannot create customer satisfaction just by meeting customer’s requirements fully because these are to be met in any case. However falling short is certain to create dissatisfaction of the customers. Customer satisfaction is seen as a key performance indicator within an organization and is often part of a balanced score card. Low levels of customer satisfaction adversely affect the sales and profitability of the organization. In a competitive marketplace where organizations...

Roll Pass Design Jun18

Roll Pass Design

Roll Pass Design  Long products are normally rolled in several passes, whose numbers are determined by the ratio of the initial input steel material (square or round billet or bloom) and final cross section of finished product. The cross section area is reduced in each pass and form and size of the steel material being rolled gradually approach to the desired profile. Rolling is carried out between grooved rolls. Two opposite grooves in the collaborating rolls form a pass, which corresponds to a work piece’s cross section shape expected after the pass. After every pass, the cross section decreases and its shape becomes closer to a shape of the final product. Development of subsequent pass shapes and its proper location on the rolls is called the roll pass design. Roll pass design is an essential part of long product rolling process, since the long products are rolled between the shaped rolls in the long product rolling mills. Roll pass design generally means the cutting of grooves in the roll body through which steel to be rolled is made to pass sequentially to get the desired contour and size. The primary objective of the roll pass design is to ensure production of a product of correct profile within the tolerance limits, free of defects, with good surface quality and the required mechanical properties. In addition, economic condition must be achieved while rolling the product, for example, maximum productivity at the lowest cost, optimum energy utilization, easy working conditions for the rolling crew and minimum roll wear. Roll pass design is a set of methods for determining the dimensions, shape, number, and type of arrangement of rolling mill passes. Roll pass design also includes the calculation of pressing forces and their distribution on the roll passes. Several   passes are made for each section; a square or round billet or bloom acquires a specified form on each successive pass. The roll passes are designed to avoid excessive stresses in the steel being rolled, since such stresses can lead to the formation of cracks and other flaws. Roll pass design is based on the characteristics of initial input...

Interstitial Free Steels...

Interstitial Free Steels  The term ‘Interstitial Free steel or IF steel’ refers to the fact, that there are no interstitial solute atoms to strain the solid iron lattice, resulting in very soft steel. IF steels have interstitial free body centered cubic (bcc) ferrite matrix. These steels normally have low yield strength, high plastic strain ratio (r-value), high strain rate sensitivity and good formability. Conventional IF steels which were developed commercially in Japan during 1970s following the introduction of vacuum degassing technology contained carbon (C) in the range of 40 – 70 ppm and nitrogen (N) in the range of 30 -50 ppm. Later, niobium (Nb) and/or titanium (Ti) were added to these steels to stabilize the interstitial C and N atoms. IF steel is termed as ‘clean steel’ as the total volume fraction of precipitates is very less. In spite of this, the precipitates appear to have a very significant effect on the properties of IF steels. Liquid steel is processed to reduce C and N to levels low enough that the remainder can be ‘stabilized’ by small additions of Ti and Nb. Ti and Nb are strong carbide/nitride formers, taking the remaining C and N out of solution in liquid iron, after which these latter two elements are no longer available to reside in the interstices between solidified iron atoms. IF steel has ultra low carbon content, achieved by removing carbon monoxide, hydrogen, nitrogen, and other gasses during steelmaking through a vacuum degassing process. Interstitial elements like nitrogen or carbon are also in the form of nitrides and carbides due to the alloying elements such as Nb and/or Ti used for the stabilization of the residual interstitials. Therefore, IF steels posses typically non aging properties. Because of their non ageing properties, IF steels...