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Saving of Energy in Cement Production

 

Use of a large-scale cellular wheel sluice with mechanically forced discharge for feeding wet and sticky raw material into the drier

The challenge in terms of sustainability:

A problem that has not been solved for years in the construction of cement plants was the reliable and batched sluicing of the ingoing material for cement production into the air system under high negative pressures of a vertical roller mill or a high-speed impact wheel drier in the preheating compound of the cement kiln plant (semi-wet procedure). 
The starting material is a wet, abrading chalk and marl with the tendency to stick. A successful solution of this task would reduce enormous heat losses and thus clearly diminish the use of energy (heating oil or others). Thus, cement production, in particular in Eastern Europe, where the semi-wet procedure is still used, can be op-erated more ecologically and more power-efficiently in the long run.

The initial situation:

In a cement factory built in 2004 at Chelm, a town located in Eastern Poland, the three-fold rotary lock supplied by the erector of the plant was removed again because of high product sticking already after a short operating period. For years, the kiln plant has still been operated by accepting high losses of air entering through a leak and/or of heat and throughput via an open pressure shaft. The erected plant consists of a rotary tubular kiln with a planned throughput of 4,500 t/d. For this particularly sophisticated case of application, KREISEL GmbH & Co. KG developed for the first time a clearing cellular wheel sluice which had to be in a position to reliably feed an hourly mass flow rate of approx. 400 t of the impact wheel mill while, at the same time, the gas regime had to be sealed against negative pressures of up to 5,000 Pa.
Further goals:

  • Process optimisation by avoiding air entering through a leak
  • Noise reduction
  • Stabilisation of the drying process by eliminating fluctuations of temperature caused by the climate

 

The solution:

The developed clearing cellular wheel sluice consists of a cellular wheel with a diameter of 1,800 mm and an overall height of 3,000 mm. It is driven by a geared motor having an output of 15 kW. Both, the housing of the sluice and the cellular wheel itself, have been equipped with exchangeable anti-wear plates. The access to the cellular wheel and the clearing tool is possible through respective inspection openings. This way, it will also be possible to repair the clearing knife without any problems. The sluice can be heated and is protected against dust and choking in the outer side disk area by using scavenging air. Meeting a request of one of our customers, the clearing cellular wheel sluice was placed onto a mobile unit specially designed for this case of application. Thus, in case of repair work or also for the purpose of inspections that had to be con-ducted at regular intervals, it was possible to laterally move the clearing cellular wheel sluice out. The plant was commissioned at Chelm from 27 April to 01 May 2007 with the staff members of KREISEL GmbH & Co. KG being present. Since this time, the plant has been running in continuous operation without any notable disturbances.

The sustainable strengths:

The benefit of this solution is a considerable reduction of the environmental impacts, protection of the resources and decrease in costs for new plants.

  • Reduction of the CO2 emission by saving approx. 600,000 litres of heating oil for each plant (1,680 tons of2/a )
  • Improvement of quality of the cement because the whole process runs under stable conditions by being hermetically closed off
  • Reduction of power consumption, for example for fans because less air is blown
  • Reduction of the investment costs for new plants by diminishing the cross-sections of the ducts and the fan performances (material, power)
  • Reduction of the noise level at the point of material feeding from originally 140 dB to 110 dB

If one takes into consideration that, since 2008, after the introduction of this solution on the market, between 5 to 10 plants have been ordered on a worldwide scale, the sustainable advantage is remarkable. The clearing cellular wheel sluice that has been developed with the support of Deutsche Bundesstiftung Umwelt (German Environment Foundation) in cooperation with the Polish cement factory at Chelm will be introduced on the market just at that time when the need for efficient and, in particular tightly closing material sluices has raised to a high extent in cement industry due to the increased use of the vertical roller mill. However, multi-fold fields of application in other industries will also result for the new sluice, such as handling of especially difficult secondary materials, for example sewage sludge.

The inventors:

The following staff members decisively took part in this development:

  • Mr. Ralf Trautmann: Head of the design department for bulk material engineering
  • Mr. Uwe Vogt: Design engineer for bulk material engineering
  • Mr. Stanislaw Masny: Staff member of the marketing department in Poland

Brief profile of the company:

Name: Kreisel GmbH & Co. KG
Main place of business: Krauschwitz
Year of foundation: 1912
Number of staff members: 112
Solutions: Bulk material engineering, dust removal equipment, pneumatic conveying systems, recuperators/heat exchangers, tank construction, service, job order production 
Internationality: KREISEL GmbH & Co. KG located at Krauschwitz (main place of business), KREISEL Engineering GmbH & Co. KG at Hamburg (branch establishment), representations for Russia, France, the Netherlands, Poland, Austria, India, and South Africa