Modern lime kiln technology
At the invitation of the Dannenfels-based Schwab GmbH, more than 50 experts from the lime industry met at the headquarters of the M-Group in Lemgo on the occasion of the workshop “New kiln type QualiCal Syn 85” from 10th to 11th May 2012 (Fig.1). On their completion at Calcis Warstein GmbH & Co. KG, currently two QualiCal kilns are waiting to be commissioned – one at Calcis Lienen & Co. KG and the second one at Kalkwerke H. Oetelshofen GmbH & Co. KG in Wuppertal. During the course of the workshop, the participants could exchange ideas with the companies involved in the manufacture and with the operators as regards the plant concept and implementation.
Refractory and plant technology
After the welcoming speech by Harald Schwab from Schwab GmbH, Klaus Röpke from Möller GmbH talked about the company history of the M-Group and its range of services. With a turnover of 35 million € in 2011, the group of companies focuses on the core business (Fig. 2) of refractory technology (Schwab GmbH and Möller GmbH) and plant technology (Eberhardt GmbH). The philosophy of the company is “always to be part of the solution and not part of the problem”, which is also the company motto in 2012.
Products for the lime, sugar and soda industries
The next lecturer was Michael Hünerlage from Eberhardt GmbH who presented various different company products, amongst other things, the new Hoist Safety Unit (HSU), which ensures the durable safety as well as the braking readiness and operation of the hoist without any manual tests. Examples of other current projects were a conversion project for the kiln hood including a static stone distributing device and, for major throughputs, the calcining kiln feed. At present three lime kilns from Eberhardt (1 x coke, 2 x gas) are being set up worldwide. Two interesting orders in Germany include the conversion of two existing kilns with combined firing from coke to natural gas. These kilns have a shell diameter of 4.6 m. The current planning includes three further orders for the conversion of kilns with a diameter of up to 7.0 m to be fired with natural gas. Hünerlage pointed out that of course the group is not only implementing technologically elaborate concepts but also solves problems together with the customers and tailors and further develops the plant technology.
Further developed lime kiln concept
Dr. Carlo Cella then presented the QualiCal range of ser-vices. QualiCal is able to supply double-shaft kilns with a throughput of up to 800 t/d (quicklime) or 40 t/h (hydrated lime), respectively, for many fields of application. As the designation ‘synthesis kiln’ already indicates, the core of the kiln concept is the synthesis of various construction advantages of lime kilns in one design. QualiCal kilns are double-shaft-kilns that are distinguished, amongst other things, by varying geometries of kiln height. Curved cross-sections are used for the preheating and burning zone, whereas rectangular cross-sections are used in the discharge zone. A direct overflow duct allows the unhindered exchange of process gases.
Follow-up project after successful execution
Per Wasner from Calcis described how the project management and positive experience gained with the Warstein project also influenced the planning of the new kiln from QualiCal in Lienen (see page 55). The kiln at Warstein was commissioned in 2011 after a project time of only 12 months, in part under difficult winter conditions with -20°C. Due to the perfect cooperation with the producer, the guaranteed values were achieved only one month after commissioning. Besides a consistent lime quality, the kiln is distinguished by very low dust emissions (< 2 mg/m³) and noise levels below 45 dba at a distance of 180 m.
Clean and exact proportioning
After the lunch break Andreas Hentschel from Carbotechnik lectured on proportioning plants for lime kilns. A prerequisite for the plant from Carbotechnik is a dust that can be fluidized, e.g. lignite dust. The exact and clean proportioning is carried out by means of proportioning discs operating in a pressure- and shock-resistant casing.
Metal construction and installation
Then Guido Prinz from Hoffmeier presented the range of services of the company. In their own manufacturing department even plant parts with large volumes can be fabricated by means of the latest technology. In special cases it is possible to transport huge plant parts to the site by ship. In addition to steel and plate construction, Hoffmeier also carry out the installation or the conversion of plant parts, such as mills, kiln hoods etc.
Installation and programming in the cement and
lime industry
André Sommavilla and Christian Schweer from the companies ESL GmbH and ESL Automatisierung continued the program of lectures.
ESL GmbH carries out the electrical installation and cabling of plant parts in the lime and cement industry worldwide. ESL Automatisierung, carried out, amongst other things, the programming of the plant from Carbotechnik and the handling of lump lime in Warstein. One general focus of the company is on the control migration. A check is carried out to verify whether existing control components could be further used or would have to be replaced by new systems.
Optimum and cost-effective lining
The quality of a kiln depends on its refractory lining. In this connection, Harald Schwab explained in the concluding lecture how the optimum lining of a QualiCal kiln could look. The advantages of the kiln, compared to annular shaft kilns and PFR kilns, are the less different refractory brick types, predominantly standard formats, a lower refractory volume and weight, respectively, and, consequently, shorter lining times.Splitting up the overflow duct into various zones, i.e. an upper and lower central zone and the adjacent left and right wear arch, ensure quick replacement of parts in case of wear because partial replacement is possible.
During an evening event, participants had the opportunity to exchange views and to discuss the lectures. On the following day they could intensify and complete the information received the day before in the Lienen plant.
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