High flexibility plant for Western Australia made by KELLER HCW
[May 2006] One of the most modern brickworks in the world, built by KELLER HCW, was officially opened at the beginning of May in Perth, Australia. Apart from the standard Australian extruded brick format the new plant produces soft mud bricks, fast wall internal bricks, blocks, facing tiles, various paver formats and special shapes.
Introduction
Boral Midland Brick, Western Australia’s leading manufacturer of clay brick and pavers, has officially opened its new manufacturing plant in Perth, Western Australia. After a long and thorough tendering and approval process, Midland Brick chose KELLER HCW GmbH, Ibbenbüren-Laggenbeck (Germany) as the principle contractor.
The plant was officially opened by the Minister for Housing and Works and Member for Midland, The Hon Michelle Roberts MLA, with Mr. Rod Pearse, CEO & Managing Director of Boral Limited. The new Kiln 11 is the most technologically and environmentally advanced kiln in the southern hemisphere and has the capacity to produce 52 million standard bricks a year. When fully commissioned it will allow the closure of the 40-year old Kiln 4, which has 20% less capacity.
Kiln 11 is an extremely flexible plant built for the production of both extruded and soft mud products, producing a greater variety of bricks, blocks, pavers and facing tiles in all ranges, and will allow Midland Brick to produce thinner facing tiles and two course soft mud bricks, a first for Western Australia.
During its detail design phase, detail discussions were held between KELLER HCW and Midland Brick personnel ensuring that all aspects of plant design and safety were covered so that minimum manning levels could be achieved for both production and maintenance.
Preparation and moisture control
The raw material is stored in Midland Bricks existing expansive raw material store and is fed via the new pre-mixer line and fine rolls to a box feeder within the new building. The moisture levels in the clay are measured and controlled by two Cellawave GZ01 moisture control systems supplied by KELLER HCW. The first control and water addition is at the pre-mixer and a second unit at the mixer in front of the extruder, alternatively at the mixer in front of the soft mud machine depending on which system is running at the time. For face bricks, molasses are added at the pre-mixer and this is also controlled by the Cellawave system.
The Cellawave is a completely new system, developed by KELLER HCW, using microwave technology to measure and control the moisture content in the clay. The electromagnetic waves permeate completely through the product and, contrary to optical methods, they measure the volume of moisture. The sensor works with a frequency of 2.45 GHz and allows about 10 measurements per second making it extremely suitable for analyzing the moisture content of quick moving materials. The microwave measuring method use the distinct dielectric properties of water. The accuracy and repeatability of the sensor is typically ± 0.2 M.-% moisture, depending on calibration. For more information on this system please contact KELLER HCW.
Shaping
The raw material is fed from the surge box feeder via a series of conveyors to the double shaft mixer and extruder. The final moisture check is done at the headstock of the conveyor feeding into the mixer and water is added just below it in the chute. The de-airing extrusion machine and double shaft mixer is a Steele 90 taken from within the Boral Group, refurbished and modified by Midland Brick to maintain an extrusion with a penetrometer reading of up to 3.2 Kg/cm². To facilitate rapid product change and to cope with the various formats ranging from blocks to tile facings, the drives in the shaping area are all speed controlled.
The soft mud bricks are produced with a Hubert 3 head machine with the new heads being supplied by De Boer. The mould chain and ancillary equipment was supplied by a local West Australian company Centrix Engineering Pty Ltd and clay conveyor systems by Transmin Pty Ltd.
Extruded brick production
After extrusion the clay column runs through a texturing machine, which has the capability of texturing, sanding, adding materials to the column surface such as sawdust and clay slurry, dry powder and spraying. The bricks are cut by a KELLER HCW in-line „Universal" cutter with the possibility of chamfering stretchers and headers on all sides.
Brick transport
The cut bricks are transported via a multi-strand conveyor system, capable of carrying all the different formats, to a transfer gripper which picks the product off the conveyor with in-line tracking and sets them down on the aluminium pallets. There are three alternative transfer grippers at this point to satisfy all products and these can be changed semi-automatically in a short time to minimize changeover times. When running soft mud bricks, the loaded pallets enter the system at this point on the pallets for loading into dryer cars. The loaded pallets are loaded into specially treated dryer car frames layer by layer for transport through the dryer (Fig. 3).
There is a semi-automatic line just before the loader where pallets loaded with bricks can be diverted through a separate system. Special shapes can be hand formed on this line before being re-introduced back into the system for drying.
Dryer
The dryer for Kiln 11 is designed as a double tunnel dryer with slotted jet walls, reversing air circulation and is 75 metres long. There is a wet storage in either tunnel to cope with shift changeovers and maintenance times. There are sluices in either tunnel at the exit end and the dryer is divided into six control zones. All steelwork in the wet end is a special corrosion resistant stainless steel and in the dry end galvanized steel. There are 46 re-circulating fans, 23 in each tunnel, and six wet air fans, three in each tunnel.
For the drying process, excess cooling air is taken from the kiln and if necessary supplemented with ambient air (Fig. 4). There are two auxiliary gas burners after the hot air fan, which can also be used when required. Electronic sensors for temperature and moisture control, in conjunction with the automatic process computer system "K-Matic TD", are used to set the optimum drying curves for the individual zones so that by automatic product tracking the different formats will be dried with the best possible water extraction curve. The dryer passage time for the reference standard soft mud bricks is 21.1 hours.
Dry side
The bricks are unloaded from the dryer cars with the identical equipment used for loading. The bricks are taken from the pallet by a robot using a double gripper and set down on the double row in-feed to the setting machine. At this point there is the opportunity to remove special shapes which cannot be run through and automatically set by the setting machine. The empty pallets are then cleaned, measured and stacked before being moved into the pallet storage. The pallet storage system is sufficiently large so that it can accommodate all pallets within the system without the need to remove pallet stacks by fork lift.
Setting machine
On the double row in-feed to the setting machine the bricks are grouped and can then be sanded before being doubled or inverted. The bricks are pushed off the in-feed conveyors into the setting machine, grouped, separated with a cellaflex unit and set on kiln cars by 2 × 450 Kg robots (Fig. 5). There is an auxiliary line running parallel with the kiln cars where special shapes, which can be removed from the pallets by the robot and are able to run on the in-feed conveyors towards the setting machine, but which cannot be automatically set, can be loaded manually on top of the kiln car.
Kiln
The kiln is a top fired tunnel kiln approximately 115 meters long with a four car pre-heater and an exit sluice (Fig. 6). Because of its inlet pre-heater and exit sluice, the kiln is a closed system and it is therefore possible to adjust defined pressure profiles in the firing chamber to suit each product. The firing chamber is sealed by the use of an internal steel membrane on the walls and ceiling as well as by a special wheel cooling system on the floor.
The kiln is fitted with four high velocity burner groups in the pre-fire zone fitted as side burners, 14 groups of injector burners in the ceiling plus a further group of high velocity burners also in the ceiling. This group of high velocity burners is used not only in the process but also for starting the kiln from cold. The kiln is also set up for flashing.Rapid cooling groups, in conjunction with the upper take-off, the final blow in fan and the lower take-off provide the product cooling.
The kiln is controlled by the automatic measuring and control equipment using Simatic S7 and the "K-Matic" process computer system. In addition kiln car tracking is controlled by this computer. The "K-Matic" process computer system not only allows for the automatic kiln operation, but also for the reproducibility of the individual firing recipes. Remote monitoring by means of Teleservice allows not only for the internal remote monitoring by the home computer, but also for remote process support and software updates by the supplier.
Unloading
After exiting the kiln, the kiln cars are transported to the kiln car unloading station, which unloads over one track. Using the kiln car unloading gripper complete packs are removed from the kiln car and set down on a bar chain conveyor (Fig. 7). At this point bricks from stock can be blended into the system by placing a hack on the small set-down table with a fork lift and moving them onto the bar chain conveyor with the unloading gripper. The packs then move to the next station on the conveyor to the desticker (Fig. 8). After desticking the packs move into the unloading position where two robots remove the bricks layer by layer and set them down on a table. The bricks are then grouped and can be de-doubled, de-faced and turned according to the dispatch packs required. The bricks are then formed into dispatch packs and are strapped with or without pallets before being transported into stock.
Following unloading the kiln cars are cleaned before moving back into the setting line.
Technical data Midland Brick, Kiln 11
Working time:
7 days / week
2 shifts / day
10 hours / shift
Output:
52 million SBE’s / year
Soft mud bricks and / or
Extruded bricks
Reference size:
Facing bricks 230 × 110 × 76 mm
Total of 38 formats
Dryer:
Jet wall tunnel dryer – 2 tunnels
Brickwork/concrete/steel
Wet storage – 8 dryer cars in each tunnel
35 dryer cars in each tunnel
Drying time for reference product: approx. 21 hours
Dryer length: 76 metres plus wet storage and exit sluice
Total length: approx. 95 metres
Kiln:
Top fired kiln, brickwork
4 kiln cars in pre-heater
25 kiln cars in kiln
Firing time for reference product: approx. 24 hours
Kiln length: approx. 115 metres plus pre-heater and exit sluice
Total length: approx. 139 metres
Kiln car:
Car length: 4,560 mm
Car width: 5,910 mm
Further information can be found under the following links:
Video 06/2006
Kiln 11 »
Video 02/2006
Universal cutter with chamfering device »
Video 11/2007
Universal lateral cutter – 40 mm edge set pavers »
Video 11/2007
Universal lateral cutter – 50 mm edge set pavers »
Project data of the plant »
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