Autotherm Equipments Corporation is well known manufacturer,exporter and supplier of Cokeless Cupola Furnaces at market leading price from Coimbatore,, . EcoMelt Cokeless Melting Furnace is a Vertical Shaft Melting furnace and was as a melting unit for Cast iron without use of coke as in a conventional cupola. The development of the cokeless cupola began in the United Kingdom at the foundry of Hayes Shell Cast Limited in the mid s. A pilot furnace was built.
KG shows application examples cokeleas cupolas. This picture highlights conventional coke melting rightand the cleanliness of the cokeless cupola also operating, left. Depending on the requirements, the iron can then be cast or adjusted to the required analysis and temperature in an induction furnace. It acts as a source of heat In the bed it superheats the iron as it trickles over the coke It acts as a source of carbon In the Cokeless Melting Furnace these functions are provided by three cokelesx means: An electric furnace furance not a very efficient melting unit but once the metal is liquid the superheating of the iron is very efficient.
The lining may be consumable and may comprise a silica ganister, or for certain applications a lining with a high alumina content.
USA – Method of operating cokeless cupola – Google Patents
Some examples will now be furjace to illustrate what can happen when a cokeless cupola is not run in accordance with the invention. In both cases when the slag flows it is sufficiently fluid to flow easily. EXAMPLE I In a cokeless cupola lined with a high alumina material, and operated for one week without repair although melting on only a single shift, the quantity of dollastone added to take care of the dirt, and the products of wear on the spheres and the wear on the lining was of the order of 2 to 2.
A pilot furnace was built during to prove the ideas of melting cast iron with gas at a relatively low temperature and then fhrnace by some other means. For these foundries where vokeless is being considered, the capital investment of cupkla a gas or oil fired Cokeless Melting Furnace could well be considerably less than adding additional electric furnaces. The main features are the water cooled grate, consisting of steel tubes which may ckeless coated with refractory for insulation on smaller cupolas as shown left.
To take advantage of the availability of natural gas in many cupolz of the country, Cokeless Melting Furnace should be used extensively. This means higher rate of consumption of spheres. Running the furnace at low slag volumes makes the slag thick and can cause blockage of the slagging and tapping box.
To achieve tapping temperatures of around to deg C a bed height of around mm would be required. High draw speed plate blank continuous casting low carbon steel crystallizer protective slag. Search Expert Search Quick Search. Liquid metal could be transferred from the Cokeless Melting Furnace to the existing electric furnaces where they would be used for superheating and recarburising the metal instead of purely ccupola.
This means that an operator continually has to release the slag by breaking the crust on the top of the box with a suitable bar, which is hot and heavy work. This illustrates the need to keep the slag sufficiently fluid to enable it to flow through the bed properly. This is called duplexing. A cokeless cupola operating with a clean charge and with what were mistakenly thought to be correct proportions in the charge including 12 Kg of dollastone cjpola charge was found to exhibit very rapid consumption of the spheres, with the consequence that the bed almost vanished by the end of an eight-hour shift, resulting in cupols superheating and low metal temperature.
Washers and increasingly also fabric filters are used for dust removal see Dedusting.
However, with continuous tapping we have found that this low slag volume can cause operational problems as the slag cupolw not flow continuously from the front tapping and cuppla box. Another way of deliberately increasing the volume of slag in the furnace is to re-cycle the slag. Each burner has its own gas, air and oxygen valves for precise regulation of burner performance.
According to a second aspect of the present invention we propose that if the slag volume is not sufficient to flow properly when required during tapping then a combination of limestone and silica is added to the charge to deliberately increase the volume so that the slag flows continuously and makes the operator’s job easier.
US5294243A – Method of operating cokeless cupola – Google Patents
In addition most cupola furnaces are lined with a refractory material and as this gradually wears away this material must also be absorbed into the slag.
Moreover in many instances the cokeless cupola is operated as a long-campaign furnace as this is a more energy-efficient method of operation than a series of short runs and it forms an important part of the way the furnace is used. As with other cupolas, steel scrap, scrap iron, return scrap, pig iron and slag forming agents can be used as charging materials.
On the other hand, although we propose to add more fluxing material than is conventional, if too much fluxing material is added, with a view to keeping the slag fluid, the cupo,a will be attacked by the fluxing materials, leading to a high consumption of spheres which not only increases the operating cost but also, because of the reduced thickness of the bed as the spheres are consumed, leads to problems of insufficient superheating of curnace metal and consequently low tapping temperatures.
The metal is pre-heated in the upper part of the furnace and melts just above the spheres; it is then superheated as it trickles down over the spheres.
Tapping temperature has the main influence on economics, which as described above depends mainly on bed height. Automatic combustion control and indication of condition of all important services can be provided, as shown below.
Immediately the slag flowed with good fluidity and the bridging problem disappeared. The limestone absorbs the ash into the slag and leaves the carbon exposed for these two functions. The quality of the fuel cokeHC coke and the combustion process itself must be reproducible since all fluctuations have an impact on the melting process.
Another way of deliberately increasing the volume of slag in the furnace is to re-cycle the slag. We have to import coke from other countries.
In addition most cupola furnaces are lined with a refractory material and as this gradually wears away this material must also be absorbed into the slag. Pig iron Foundry pig iron Furnace clogging Literature: A method according to claim 2 wherein limestone, dollastone is added to the re-cycled slag as another component of the fluxing agents. In a unit melter fairly high tapping temperatures will be required. A wide variety of metal charges can be melted in the cokeless cupola and generally a similar charge to a conventional coke fired cupola can be used.
Wesman Group of Companies, Kolkata. This slag volume would then in cypola circumstances co,eless similar to that in a conventional coke cupola.
The examples show the importance of slag control. This is the purpose of the addition of limestone to the charge in the furnace; the limestone acts as a flux to absorb all these unwanted materials and form a slag which can be easily removed from the furnace and handled outside.
This normally results in excessive consumption of the heat-exchange bodies. With correct charge materials the sulphur content of tapped iron can be below 0.
A method according to claim 6 wherein the silica comprises broken bottles, jars, gravel. This is certainly true for foundries in India where the cost of meeting new regulations is significant.
At the same time, flux is still necessary to absorb the material originating from wear of the furnace lining and whilst in some cases a similar lining is used and the action is therefore similar, the actual lining consumption is much less, so here again there is a difference resulting in a lower need for a flux. Long-term furnace In line with the current state of the art, a long-term furnace can be designed with or without a lining.
Based on its principle, the cupola furnace is a shaft melting furnaceit is filled with fuel cokemetal charge pig ironcirculation material, scrap steel and slag -forming additives limestone from the top. Looking directly into charge of a gas cupola during operation – cleanliness is apparent.
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