Roller dryers for roof tiles

Sacmi supplies new plant for Creaton/Etex in Poland

»1 and 2 El Aguila, Leon, Mexico: a line producing 60 000 interlocking glazed Portuguese roofing tiles per day

»4 Nuovo Corso, Italy: view of E5E dryer, two ventilated façade production lines (max. dimensions 1 200 x 3 000 mm), 1 500 m²/day

»5 and 6 Caribbean Roof Tile, Trinidad & Tobago: S-type and Roman-type roof tile production line. Daily output 40 000 S-type roofing tiles

»7 Kashi Shirkouh Yazd, Iran: three Portuguese and Marsigliese interlocking roof tile production lines, output 22 000 glazed roofing tiles/day per line

Rapid on-roller drying of extruded ceramic products with a moisture content of 16–20% was first introduced onto the market by Sacmi in the 1990s.

This need arose as a result of increases in the surface area of thin extruded products in order to meet the market demand for ever larger tiles, roofing tiles and ventilated façades. Drying of such products on racked cars in traditional tunnel or chamber dryers had become impossible: blowing air onto what was merely the corner of a large piece was nothing less than absurd. Bear in mind that 5% shrinkage over a linear metre corresponds to a huge 50 mm! If such extensive shrinkage were to start from one side only, internal tensions within the material would inevitably lead to cracking.

It was therefore evident that a radical change in the type of machine was required and that products needed to be dried individually with uniform ventilation perpendicular to the product surface. Moreover, uniform shrinkage and the resulting absence of interior tensions allow significant speeding up of the drying cycle.

For this reason, Sacmi introduced 3, 4, 5 and 6-layer rapid roller dryers – for extruded tiles, roofing tiles and ventilated façades – onto the market. Each layer (or level) of the dryer constitutes an independent channel where the product is brought into contact with this “technological air” from both above and below by way of blower pipes emitting high-speed air jets. These upward and downward flows can also be adjusted independently.

Dryer design also focused on another key aspect, that of discontinuous operation. The reasons for this are numerous and well known: for example, the need to run the dryer on a 2-shift basis only or interrupt production (press mould cleaning, non-continuous work shifts, etc.).

It was decided to build these roller dryers, then, in 5-metre-long fully independent macromodules, each equipped with its own burner, air circuit and independent chimney. Each module also features automatic adjustment of humidity and temperature. As it is effectively an autonomous cell there is no contra-flow air along the entire dryer length. This means that producers can set up a step-type curve corresponding to the macromodules and follow the Bigot curve in as precise a manner as possible, with the ensuing possibility of discontinuous operation.

Dozens of these dryers have been installed for the production of ventilated fa- çades, extruded flooring, step pieces, pressed roof tiles and extruded roofing tiles (»1 to »7)

Roofing tile roller dryer for Polish roofing tile factory

The latest installation, due to come on line in summer 2012, is in Koscian, Poland, at a new Creaton/Etex plant that will produce 30 mill. roofing tiles a year (10
pieces/m²) and 2.4 mill. trims.

For this plant, Sacmi’s Heavy Clay Division has supplied the entire drying department, which consists of:

› two rapid roller dryers

› frame automation and storage system (RAT)

› eight static cells and relative RAT plus automation and cars for trims

Each dryer has the following characteristics:

› length: 78.9 m,
width: 3.8 m

› number of levels: 6

› drying cycle: 220 min.

› energy consumption: 1 150 Kcal/kg of evaporated water

› roofing tile support frames measuring 565 x 3 660 mm and containing nine roofing tiles. The total number of frames for a plant with two roller dryers is 2 000. For a corresponding traditional dryer, 10 000 – 12 000 frames would be needed

To optimize energy consumption, great attention has been paid to the design of the system that recovers hot air from the kiln. The additional energy is provided by innovative burners that also use the hot air as combustion air (up to 230 ° C). Most fans are inverter-assisted to ensure lower electricity consumption.