Filter Technology & Gas CleaningEMC Filter Technology
EMC filter technology from Scheuch has revolutionised dedusting in the cement industry and set new standards in bag length, pressure loss, cleaning pressure and bag service life. The results point to clear reduction in life cycle costs (LCC). Thanks to its patented status, EMC is unique and is deemed to be the Best Available Technology (BAT) for process filters – even when compared with electrostatic and reverse-air filters. More than 200 EMC filter plants installed within the first ten years of this technology outline its pre-eminent status worldwide:
- Volume flow rate up to 3,000,000 Bm3/h
- Filter area up to 40,000 m2
- Bag length as much as 12 m and beyond
- Dust quantity over 1,000 g/m3
- Hot gas design up to 280oC
Kiln Dedusting – Cement Industry
Thanks to the development of filter media that is suitable for higher exhaust gas temperatures and the growing trend towards the use of secondary fuels, bag filter plants have eclipsed virtually every other kind of system when it comes to today’s kiln dedusting applications, with some electrostatic precipitators being converted into bag filters.
Because of their size, kiln filters are the ideal application for EMC technology, allowing it to tap into their full potential for using energy efficiently and making operating cost savings. Additionally, EMC filters operate with a stable level of differential pressure – that is, without fluctuations – and are not affected by the kind of temporary overloading that occurs when secondary fuels are added, in kiln sections or during switchover processes, for instance. As a result, this application is guaranteed to offer maximum plant availability during continuous operation. This unique technology uses bag lengths of up to 10 m, something which has positive repercussions for investment costs too. Even bag lengths of 12 m and more can be used.
Clinker Cooler Dedusting – Cement Industry
Because of the temperature peaks of 500 °C and higher that occur in upset mode, in most cases Scheuch installs an air/air heat exchanger upstream of the bag filter for gas cooling purposes. It is critical that this system has a carefully designed control and safety concept that enables the heat exchanger to respond to upset mode in good time.
The main benefits that EMC technology offers in clinker cooler dedusting applications are the significantly longer service lives of the filter bags and the reduced differential pressure levels – resulting in reduced operating costs throughout the plant’s life cycle.
Mills & Sifters – Cement Industry
The lumpy material is transported to the silo plant on a conveyor belt and is either sold in its lumpy format or ground into fine material. The process of grinding clinker, blast furnace slag or slag sand produces extremely fine dust in significant quantities: it is not unusual to see as much as 1,000 g/Bm³. A key requirement in these applications is a uniform filter inflow in order to ensure efficient material recycling.
EMC filters operate with low levels of pressure loss and minimum compressed air consumption – regardless of the type of mill or sifter construction. The main advantage of EMC technology in grinding plants is the consistently low level of differential pressure and considerably longer service life of the filter bags. This makes it possible to achieve a constantly high level of product quality as well as reduced operating costs throughout the entire life cycle.
Shaft Kiln Dedusting – Lime Industry
The lime industry carries out lime burning tasks almost exclusively in shaft kilns. The lumpy raw material is burned in the shaft kiln at temperatures of 1,000 to 1,500 °C.
Thanks to the development of filter media that is suitable for higher exhaust gas temperatures, bag filter plants have eclipsed virtually every other kind of system when it comes to today’s kiln dedusting applications, with some electrostatic precipitators being converted into bag filters.
In contrast to rotary kilns, shaft kilns have a vertical design. They are also equipped with rupture discs to counteract overpressure; in fact, they are ideal for applications where overpressure occurs simply by virtue of their structure.
Rotary Kiln Dedusting – Plaster Industry
Rotary kilns are a very common sight in applications where plaster of Paris is being manufactured. They are ideal for burning granular gypsum rock that is continually dispensed into them together with hot gases and without a pre-drying process. They are made up of thick steel sheets with baffles that ensure the material is distributed evenly.
As a result of trends such as the use of recycled material, bag filter plants have eclipsed virtually every other kind of system when it comes to today’s kiln dedusting applications, with some electrostatic precipitators being converted into bag filters.
Grinding and Drying, Gypsum Calcination – Plaster Industry
Whether the process involves grinding, drying or calcination, the aim in every case is to eliminate water from the raw material. In state-of-the-art technology, this is accomplished using an all-in-one unit. At the end of the grinding product calcination process, the exhaust air that is produced is extracted and separated in a filter.
The moisture lands in the filter, whose design has to be able to ensure that the filter medium has a sufficiently long service life. Scheuch specialises in this area and boasts years of expertise in using extraction systems in the plaster industry.
The following requirements must be considered:
- Various fuels (light or heavy oil, gas, etc.)
- Recycling material, FGD gypsum and natural gypsum with some impurities (glass fibres, cardboard, paper, etc.) land in the filter
- High moisture level
- Materials with a tendency towards caking
- Operating temperatures close to dew point (water and acid dew point) -> stainless steel design
- Intermittent operation