Install Induction Furnace

Induction furnaces offer certain advantages over electric arc or cupola furnaces. An induction furnace emits 75 percent less dust and fumes, due to the less turbulent nature of the heating employed inside the furnace. When coupled with the use of relatively clean scrap material, the need for emission control equipment may be avoided. For more information on induction furnaces, refer to USEPA (1985), and Danielson (1973). 

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The efficiency of an induction furnace installation is determined by the ratio of the load usehil power, P, to the input power P, drawn from the utihty. Losses that must be considered include those in the power converter (transformer, capacitors, frequency converter, etc), transmission lines, cod electrical losses, and thermal loss from the furnace. Figure 1 illustrates the relationships for an induction furnace operating at a constant load temperature with variable input power. Thermal losses are constant, cod losses are a constant percentage of the cod input power, and the usehd out power varies linearly once the fixed losses are satisfied. 

The induction furnace was first patented in Italy in 1877 as a low frequency furnace. It was first commercially appHed, installed, and operated in Sweden. The first installation in the United States was made in 1914 by the American Iron and Steel Company in Lebanon, Pennsylvania however, it was not successhil. Other low frequency furnaces have been operated successhiUy, especially for stainless steel. 

The capture of smoke and dust is the most difficult problem to solve when installing an olT-gas collection system on a coreless induction furnace, since there is no exhaust shaft. Several methods have been developed in the past decade, each with advantages and disadvantages. 

The installation of exhaust capture equipment is applicable to all new and existing induction furnace installations, both in ferrous and non-ferrous foundries. 

The cost and consumption data for a bag filter installation on a melting unit of crucible induction furnaces, melting 15 t/h, able to treat 120000 Nm /h are given in Table 4.44. 

A heat recovery system using the cooling oil of induction furnaces was installed in a Belgian... 

For the operation of induction furnaces, BAT is to melt clean scrap use good practice measures for the charging and operation use medium frequency power and, when installing a new furnace, to change any mains frequency furnace to medium frequency to evaluate the possibility of waste heat recuperation and under specific conditions to implement a heat recovery system. For exhaust capture and treatment fi om induction furnaces, BAT is to use a hood, lip extraction or cover extraction on each induction furnace to capture the furnace off-gas and maximise the off-gas collection during the full working cycle to use dry flue-gas cleaning and to keep dust emissions below 0.2 kg/toime molten iron. 

Low level activity metals remeltlng Installations, l.e. Induction furnaces, were designed Independently In Russia and Slovakia with financial backing of the Joint Fund, their testing carried out colloborated at Beloyarsk and Bohunlce NPP. 

Power Supplies and Controls. Induction heating furnace loads rarely can be connected directiy to the user s electric power distribution system. If the load is to operate at the supply frequency, a transformer is used to provide the proper load voltage as weU as isolation from the supply system. Adjustment of the load voltage can be achieved by means of a tapped transformer or by use of a solid-state switch. The low power factor of an induction load can be corrected by installing a capacitor bank in the primary or secondary circuit. 

Foundries utilise mechanisation and automation depending on the need for reproductivity and on the series sizes. The most flexible installation is typically the jobbing foundry. This produces a variety of products in small numbers (<100). In general, this type of foundry applies manual moulding techniques with resin-bonded sand moulds. The melting furnace works batch wise to allow an easy change of alloy. This implies the use of induction or rotary furnaces. 

The replacement of a cold blast cupola by an induction or rotary furnace is applicable imder the criteria stated above and upon major refurbishment of the installation. 

For new installations, the criteria of Table 4.14, apply besides local and site-specific considerations. If cupola and induction or rotary furnaces are indicated as most adapted, the induction and rotary types may be preferred on the basis of their enviromnental benefits. 

Today, sand bricks are used for lining furnaces such as L-D converters. These have properties similar to semi-silica bricks and are cheaper and quicker to install than normal bricks. They last as long as regular bricks and tiieir thermal conductivity are low. This reduces the heat loss from the furnace. Small induction melting furnaces with up to a three-ton capacity are lined with pure silica sand, which is rammed against a steel former. Afterward, induction heating fires it. 

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