150 years of kiln engineering and 30 years of mechanical engineering

1 Introduction

Since its founding as a brass foundry by ­Heinrich Eberhardt in 1860, EBERHARDT GmbH focused predominantly on the development and production of equipment for the sugar and soda industries. The company recently took an important and successful step into the future, however, with the integration of new know-how and the setting-up of the Schaffrath division specializing in lime shaft kilns, milk-of-lime plants and flue gas cleaning installations. 150 years of experience in lime shaft kiln engineering, coupled with 30 years of tried and proven mechanical engineering in the field of feed and hydraulic discharge systems are Eberhardt‘s basis for a large range of draft solutions for the modernization of existing lime shaft kilns, including those operated in the lime and building materials industries (Fig. 1).

2 Lime shaft kilns

The Eberhardt name has long been popularly asso­ciated only with the coke- or anthracite-fired „mixed-fuel“ kiln. This is, to some extent, understandable, when one remembers that more than four hundred mixed-fuel Eberhardt lime kilns have been installed around the world. Since 2008 at the latest, however, this identification solely with mixed-fuel kilns has been obsolete; this was the year in which two Eberhardt Type G 135 gas-fired lime shaft kilns, each with a daily output of 150 t/d burnt lime, were commissioned [1]. The operating data recorded at the time were exceeded at the recently completed inspection trials and have also been confirmed by the customer (Table 1). The relatively long period separating commissioning and acceptance is the result, on the one hand, of the campaign-based mode of operation in the beet sugar industry and, on the other hand, of the customs and practices of the Egyptian market. Both kilns are now meeting the customers‘ requirements for the third successive campaign.

In parallel, two further Eberhardt Type O 135 lime shaft kilns have now been completed and commissioned, using light fuel oil as their energy source (Fig. 2). The operating data achieved up to now are even better than expected (Table 1). The data reproduced here for the two plants relate to a limestone with a CaCO3 content of 95  %. Both kilns are to be converted to natural gas firing as soon as the plant‘s centralized natural gas supply is assured; the necessary combustion system has already been installed. To permit fuel changeover from oil to natural gas, the oil injectors (Fig. 3) are swung back into their side mountings on the combustion chamber, and the natural gas burner elements with their burner housing are inserted. The main burner is ignited by means of a pilot burner, which then serves the purpose of flame monitoring. Following this changeover, each combustion chamber can then be successively started using the new fuel.

In addition to the two oil-fired kilns, a small Eberhardt Type G 30 lime shaft kiln is also being constructed at the same location, to meet the considerably lower demand for lime for use in raw sugar refining.

At a third sugar plant, the structural steel work for three Eberhardt Type G 135 lime shaft kilns has been completed, and commissioning is scheduled for January, 2011.

This number of gas/oil-fired lime shaft kilns should, at last, put an end to the misconception that Eberhardt‘s product range consists only of mixed-fuel kilns, the more so, in view of the fact that twelve lime kilns of the gas/oil type had already been commissioned by Eberhardt up to 1979, their linings [1], combustion systems and feed systems having in the meantime also been modernized. In addition to retrofitting of an ignition and pilot burner, burner control and flame monitoring have also been implemented in a central cabinet in the burner platform control room (Fig. 4). This thus eliminates the detrimental effects of thermal radiation close to the combustion chambers, guaranteeing operation with the minimum of problems. Modern Eberhardt hoisting winches equipped with safety brakes are used, on the one hand, for the charging of the kiln. On the other hand, tightness has been improved and the potential for ingress of false air during the charging cycle thus eliminated, by means of a hydraulically operated charging bell in combination with metal-on-metal sealing and machined sealing surfaces.

3 Key components

In 2008, Eberhardt’s focus on the sugar and soda industries was broadened by the setting-up of the Schaffrath division. The newly incorporated know-how and the commitment of the key employees mean that components such as skip systems, battery charging systems, hoisting winches, charging, extraction and lime sluice systems are now available for all lime-producing branches of industry. Kiln projects of all types can now be implemented on the basis of the project management skills and the engineering and design services of the long-established expert Eberhardt. The first projects have already been successfully started, including, for example, an order for supply of key mechanical components for a new multi-chamber shaft kiln for 200 t/d burnt lime (Fig. 5) in the Ukraine, and a service package for modernization of a smaller existing multi-chamber shaft kiln in Saudi Arabia.

The bell charging systems (Fig. 6) for two high-temperature kilns in Germany have already been mechanically commissioned this year. The system here already incorporates, as a battery charging installation, the facility for expansion to serve a third kiln.

All the key mechanical components have been delivered and installed for a 200 t/d burnt lime annular shaft kiln in Russia; this plant is scheduled for commissioning in the near future. The components for three mixed-fuel kilns, each for 150 t/d, are already in store on the same site.

From 2003 to 2006, Eberhardt was definitively involved, in cooperation with a local partner, in work on five 300 t/d and 500 t/d burnt lime annular shaft kilns for the Chinese steel industry. Eberhardt continues to furnish technical consulting services and supply combustion systems for this market.

The key components developed and marketed by Eberhardt are used not only in new lime kiln projects, but also provide the basis for the modernization and optimization of existing kiln installations. Such activities include the replacement of old vibratory extraction systems with hydraulic reciprocating discharge tables, which are now standard equipment on all annular shaft kilns and on many mixed-fuel kilns (Fig. 7). The benefit of this arrangement is its volumetric discharge and thus guaranteed homogenous operation. A further modernization step is the replacement of leaking lime sluices with modern, tight systems featuring hydraulically sealing elements (Fig. 8).

Eberhardt‘s product range extends from all types of lime shaft kiln up to and including all shaft diameters. Contracts have been concluded during the past two years in the Netherlands and Germany for modernization of old lime kilns originally constructed by competing companies by means of the installation of new charging systems in order, for example, to ensure the meeting of ever stricter environmental regulations for tightness or the variable use of coke or anthracite as solid fuels. The particular challenge in this context is presented by the differing densities and the concomitant differences in the flight parabolas of these products (Fig. 9).

4 Services

In accordance with the M-Group’s holistic philosophy, not only key mechanical components, but also refractory systems and plant engineering services, are furnished for all the lime kilns mention­ed above, and indeed others, whether these are of ­Eberhardt ­origin, or of the multi-chamber shaft kiln or the annular shaft kiln type.

Eberhardt‘s range of services extends from project management, the inspection of all mechanical equipment and qualified testing of our hoisting winches, process-engineering consulting services, up to and including commissioning (Fig. 10). Comprehensive interchange of process knowledge and engineering experience with regard to various kiln types is another feature which makes Eberhardt unique in this field.

The extremely close cooperation with Eberhardt’s M-Group associate companies, Möller and Schwab, in the field of refractory systems, also contributes a significant portion of the company’s boosted process knowledge – in particular, joint kiln inspections (Fig. 11) and subsequent documentation and discussion of the causes and origins of damage or wear, and also joint drafting of design concepts for refractory lining systems. All these activities contribute to the fact that the lining is a central element in a lime shaft kiln, exercising great influence on the kiln‘s performance and its servicing and maintenance costs. The refractory systems and plant hardware must never be observed separately. There is, within the M-Group, a clearly defined assignment of responsibilities, with Schwab and Möller being responsible for refractory systems and lining installation projects, while Eberhardt is the plant engineer. Both of these sectoral demarcations apply across all markets and kiln types, with a holistic interdisciplinary orientation.

5 Innovations

Two factors are the essential force driving innovations: on the one hand, our customers who expect high levels of flexibility in fuel selection, combined with continuously rising potentials for optimization; and, on the other hand, the Eberhardt engineering team itself, which monitors and supports the entire product cycle, from the consulting stage through the bidding phase project management and design to installation and commissioning as an integrated unit. The concentrated experience from the individual project cycles, whether positive or i need of improvement, is reflected as a matter of course in the input for the next project. Internally motivated quality management is itself supported by certification in conformity to DIN ISO EN 9001:2000.

In everyday practice, the road to innovations is founded on annual customer visits and inspections of our lime-burning facil­ities and on intensive interchange of experience through customer seminars, training courses and workshops. These events are held at the M-Center, the M-Group’s communications and training facility in the town of Lemgo (Fig. 12). The proximity of the University of Lemgo and the Institute for Applied Simulation and Research Transfer is exploited to support and reinforce Research & Development activities. Flow simulation in combustion chambers [2] and bulk products, in particular, and simulation of combustion of pulverized coals in the Eberhardt lime shaft kiln are or have been the subject of completed or still ongoing research projects (Fig. 13).

6 Prospects

On May 2, 1860, Heinrich Eberhardt paid two thalers to acquire citizenship of the City of Wolfenbüttel  thus enabling him to carry on his trade as a foundry man. Nowadays, Eberhardt is firmly embedded in the M-Group corporate alliance, with a predominantly family-based shareholder structure, and with conscious social responsibility and sustainable action. The challenge of the future is faced on a solid basis of reliability, innovative creativity, willingness to invest and strict adherence to agreements. Eberhardt sees itself as a lime shaft kiln engineer, as an engineering center and as a service provider that constructs, on the basis of an equitable partnership with its customers in the sugar, soda, lime and building-materials industries, new turnkey plants, and modernizes and optimizes existing installations. The far reaching spectrum of products leaves nothing to be desired for applications for production of 500 t/d burnt lime using a range of different fuels. Eberhardt can supply modern feed, discharge and sluice systems for all types of lime shaft kiln. Thanks to the Schaffrath division, the equipment originally used is in many cases still available, irrespective of the original kiln engineer.

When the talk is of visions and the future, the M-Group is confident that it is not necessarily the size of a company, but rather quick reactions and flexibility combined with an extremely high level of quality and performance, and backed up by far-seeing, consistent and sustainable corporate policy and orientation, that are the keys to a successful future. Both of M-Group‘s business sectors, Refractory Systems and Plant Engineering, will confront the challenges of the future side-by-side and hand-in-hand. We will provide evidence that, in a globalized and networked world, reliable performance, rapid reactions and market flexibility, plus a calculable human resources policy, linked with ultra-modern technology, innovative creativity and rational management continue to be the keys to long-term and sustainable success.

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