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Bag filters for induction melting furnaces

Odsávání spalin z indukčních pecí

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The Gidly catalog includes baghouse units that are directly designed for use in applications of gas fired melting furnaces dedusting. We are offering 18 basic baghouse units for extraction of dust from induction melting furnaces, graded according to the required volumetric airflow.

Dust parameters

The dust resulted from gas fired melting furnaces is dry and made up of light particles. The exhaust gas temperature ranges from 40 ° C to 60 ° C depending on the furnace operating condition. Since it is an electric induction furnace, it is not a true combustion because all the extracted air comes from the environment of the hall and is not a flue gas by definition. The induction furnace itself does not increase the humidity of the extracted air and therefore there is no risk of vapor condensation inside the ducting and the baghouse. The extraction technology does not need to be heat-insulated.  The dust from the furnace is very fine, dark, dry and slightly abrasive.

Dedusting of the induction furnace

Modern induction furnaces come with an integrated lid that can be used in one of two states. When melting, the lid is always closed. The extraction flow rate is then regulated to about 30% of its total capacity. The regulation is achieved with valves or flaps in the extraction ducting. The fan power is then regulated with respect to the vacuum in the ducting by the usage of an power invertor. When the lid is open and the furnace is charging the extraction flow rate is at maximum.  In this moment, the smoke generated is to be extracted by the open lid to prevent spreading into the plant. The regulation valve is open to 100% and the fan power is increased to a desired value.

In most cases, a pair of melting furnaces is dedusted by the bag filter. Regulation valves and the power inverter of the fan is controled automaticaly, linked to the operation state of the furnaces or the lids positions. The extraction flow rate amount required for open lid situation is determined by the furnace manufacturer. So far, we have not met with the induction furnace manufacturer determining a extraction flow rate when the lid is closed. This state is necessary to regulate when operating the technology. The regulation then allows for energy savings when operating the furnace by not extracting too much heat and thereby unncecesarily cool the product. Another benefit of regulating the extraction flow rate during the operation of the induction furnace is also the energy saving of the baghouse and longer life of the bags. The extraction flow rate required for sufficient extraction of the induction furnace is about 5000 to 40,000 m3 / h depending on the size of the induction furnace.

Parameters of the baghouse

Baghouse units in the GIDLY catalog are fabric filter units equipped with automatic regeneration of bags by a reverse pulse jet technology. From our experience of individual extraction applications, the lifetime of the filter media lasts for more than 20,000 hours without the need of any manual refinement. The filter media are flat smooth fabric sleeves made of non-woven fabric with an antistatic coating and an area mass of 600 grams per square meter and a temperature resistance for up to 200° Celsius.  The filter medium does not contain folds where the dust be sedimented and is very mechanically resistant to tearing or scraping. The amount of residual dust particles ranges from 1 mg/m3 do 5 mg/m3 but recirculation of the filtered air is not advised – the flue gas contains a significant odor. The heat from the filtered air can be recovered using any conventional heat exchanger.

Recommended ducting solution

We recommend using Group II welded, thick walled ducting when extracting dust from induction furnaces. The proven surface treatment of the ducts is galvanizing. The ducting itself is not subject to a significant abrasion, but we do not recommend to use Group I spirally wound ducts with respect to the thermal jumps between different operating states of the furnace.

Bag filters for induction melting furnaces in the GIDLY Catalog

To find a specific assembly of the baghouse and fan, please go to the catalog and price list page. Select Baghouse units. From the list select „Induction melting furnaces“. Choose the required volumetric airflow value in the next step. The result will be a set of components – baghouse – fan – which result in the dedusting system. You can then insert the products in your costing.

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