Extraction of melting furnaces and cupolas

Home Applications Extraction of melting furnaces and cupolas

Flue gas extraction from melting furnaces is one of the most important extraction systems in foundries, smelters, and ironworks. During metal melting a large amount of flue gas, which must be extracted with a performance-stable extraction and filtration system, is created. Flue gas extraction from melting furnaces is divided into hot and cold applications according to the temperature of the flue gas extracted. Hot flue gases are created in gas melting furnaces, cupolas, and rotary kilns. The temperature at the outlet of the furnace is around 350 to 500 °C.

For extraction and filtration of flue gases, it is necessary to use filter units of special construction, equipped with a ceramic filter medium with a heat resistance of up to 900 ° C, or to cool these flue gases before this type of filtration. We used tubular coolers or recuperators, which ensure the cooling of the exhaust gases to a temperature suitable for filtration by a textile filter. Cold flue gases are extracted from electric induction furnaces. In electric induction furnaces, flue gases are not produced by burning gas or other fuel, but the molten material is gradually heated using electric induction. Flue gases are extracted using the integrated furnace lid or an additional hinged cover. The extracted flue gases have a temperature of approx. 60 to 80 °C.

Conventional extraction of gas melting furnaces

Extraction of gas furnaces is most often applied in aluminum smelting. Modern furnaces are equipped with flue gas regenerators or with recuperation exchangers. These exchangers reduce the temperature of the flue gas and transfer the energy to the flue air. Despite the flue gas regenerators is the flue gas temperature around 350 °C. We design the filtration system equipped with our own flue gas cooling system using a tubular flue gas-air exchanger. Before the cooled flue gases enter the filter unit, we add a sorbent to the flue gas to reduce the content of HF and HCl. We design the filter unit with textile filter elements with a temperature resistance of up to 200 °C. Filters are equipped with automatic regeneration of filter medium using compressed air. The filter is divided into individual chambers for the possibility of offline regeneration. The entire exhaust system must be thermally insulated to prevent condensation of wet flue gases.

Electricity generation during hot flue gas extraction

Modern exhaust systems use the temperature of the flue gas to produce electricity. This method of flue gas extraction differs from others by the return-on-investment costs. It is applicable for continuous kilns, such as rotary cement kilns or continuous casting plants. The extraction system works in such a way that the flue gases are not cooled before filtration but are filtered at a high temperature. For the filtration of hot flue gases, flue gas filters with a ceramic filter medium are used, which can withstand the effects of high temperatures up to 900 °C. The exhaust gases from the ceramic filters are led to the exchanger of the cogeneration unit. Filtration takes place in front of the cogeneration unit to prevent clogging of the cogeneration unit exchanger. The exhaust flue gases behind the cogeneration unit reach a temperature of approx. 120 °C so that there is no condensation of flue gases in the entire pipeline up to the chimney head. The whole system requires the continuity of process parameters such as the amount and temperature of flue gases.

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