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Contenu archivé le 2022-12-27

INNOVATIVE SYSTEM FOR FAST FIRING OF ROOF TILES USING ODS (OXIDE DISPERSION STRENGTHENED) SUPER ALLOY KILN FURNITURE

Objectif

Realisation of an innovative industrial system for fast firing of roof tiles, with a 39500 t/y productivity, using ODS (Oxide-Dispersion-Strengthened) Super Alloy kiln furniture.
The innovative system, which employs, as support material, a new material with higher performance and lower thermal mass than the traditional refractory material, aims to get a reduction both in energy consumption (40-50%) and in firing as well as a considerable reduction in CO2 and NOx emissions in comparison with the traditional firing system.
The operating experience in implementing the project has shown that it is not possible to use ODS in the frame with the thicknesses and mass specified in the PM-Hochtemperature-Metal design and adopted for the material supplied by the same company. On the other hand, there is no guarantee of success if greater thicknesses and mass are employed, and in any case such increases in thickness and mass would lead to increased costs so high as to be industrially of little interest.
Therefore, in order to 1. allow the host company, producer of roof tiles, to go into production and 2. demonstrate the validity of the use of super alloy support systems in the fast firing of roof tiles, ODS was replaced with INCONEL super alloy.
The project will serve as a demonstration for the European companies producing roof tiles of the advantages derived from the innovative system of fast firing.L%
The project demonstrated the validity of the fast-firing of roof tiles by means of Monker kiln as far as (i) the improvement of the quality of product, (ii) the flexibility in operation and (iii) the reduction in environmental impact (more than 50% reduction in Fluorine and Sulphur pollutants in comparison with firing in tunnel kilns).
As far as the performance of super alloy supporting materials are concerned, the project demonstrated :
1. it is not possible to use ODS in the frame with the thicknesses and mass specified in the design, there is no guarantee of success if greater thicknesses and mass for ODS are employed and in any case such increases in thickness and mass would lead to increased costs so high as to be industrially of little interest.
2. a good behaviour in operation and reliability over time of the INCONEL-SiC frames;
3. a non-sufficient reliability over time of the INCONEL saggars mainly due to non-foreseeable behaviour to creep of the welded joints.
For the latter reason, for the time being TBF decided to employ refractory saggars and is going to adopt INCONEL saggars in substitution of the refractory ones, once the results of using INCONEL saggars are shown to be positive as far as reliability over time and cost effective solution are concerned. In this sense, the solution with refractory saggars has to be considered as a non permanent solution.
As far as energy savings are concerned, the innovative support system, with INCONEL saggars, could reduce energy consumptions of nearly 25% in comparison with a tunnel kiln at the same operating conditions, thus resulting in an annual saving of heat energy equal to 326.1 TOE/Y.
Obviously, the use of saggars made of refractory material penalizes the specific heat consumption, due both to (i) the ratio between gross and net weight of the material being fired and (ii) the specific heat of the refractory material which is more than the double of that of the super alloy material.
The innovative, firing system exploits the advantages deriving from the use of ODS (Oxide-Dispersion-Strengthened) Super Alloy as a support material for the fast firing of roof tiles. The innovative firing system, engineered by Mori (patent pending PCT/EP 91/00994) and called MONKER Frame Kiln, consists of a roller kiln in which the firing product does not slide freely on the rollers, as it happens in the traditional roller kilns, but it is conveyed my means of large-sized support frames made of ODS super alloy with a section equal to the useful kiln section carrying super alloy Inconel cassettes laying on SiC bars. The frames are supported and literally moved by means of short motorised SiC (Silicon Carbide) rollers. The innovative system makes it possible to obtain energy savings up to 50% and considerable reduction in firing time in comparison with the traditional firing system, which employs H-shaped refractory cassette as support material. ODS-SiC frame present themselves asan ideal element for supporting the product in firing operation. The roof tiles supported by the Inconel cassettes are loaded onto the support frame before entering the kiln and are unloaded from the support frame at the end of the firing process in a single layer instead of being carried on piles. In such a way, the prodution line is considerably simplified and the rejection of product should be reduced.
The kiln is 102 m long and has a 9630500 roof tile productivity per year, equivalent to nearly 39500 ton per year (1 piece weights 4.1 kg). The kiln is equipped with a double conveying system, one set on the other, each one carrying a single layer of frames. Each conveying system consists of a double 500 mm roller driving system, one on each side of the kiln, the roller system is divided up into pre-assembled units, each 500 mm. long.
The kiln is a part of a continuous line connected with the dryer, it will work three shifts a day and will be in operation 350 days per year.
Whenthe roof tiles have been shaped, they are prepared on a bench, ready for loading on the Inconel cassettes, a multi-point mechanical device provides to the simultaneous loading onto the support frame of the product to be fired. The temperature for firing the product is around 1100 deg. C and the firing time is nearly 4th.
The support frames loaded with the cassettes supporting the fired product are conveyed to a storage station and from here they are picked up in a consequence for unloading.
The roof tiles proceed towards the sorting station and the packing line, while the empty support frames are stacked before being loaded again.
The monker kiln has been installed in a factory of Tuiles TBF Roumazieres-Loubert (F).

Appel à propositions

Data not available

Régime de financement

DEM - Demonstration contracts

Coordinateur

Mori SpA
Contribution de l’UE
Aucune donnée
Adresse
Via Sallustio 81
41100 Modena
Italie

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Coût total
Aucune donnée