As a system supplier, BEUMER Group develops tailor-made solutions for the specific requirements of cement plants. This includes conveying, loading and filling systems that are continually optimised and can be modified to accommodate a variety of tasks. BEUMER's goal is to allow the customer to develop a more efficient operation. For the user, this means less maintenance and a significant increase in bucket elevator capacities with precise filling results. International cement companies can modernise their plants with innovative solutions - sustainably and at low cost.
The conveying system has to meet high requirements to ensure safe and economic clinker transport in cement plants. The clinker leaves the kiln cooling system at temperatures of up to 600 degrees Celsius and is stored temporarily in the clinker silo. To ensure a trouble-free transport of the clinker, the conveying system must withstand these high temperatures. This is where BEUMER apron conveyors are used. They are extremely resistant and can navigate through complicated routings and great conveying heights. "We generally use the very robust BEUMER double sprocket chains as traction elements," explains Andre Tissen, Director Business Unit Cement at BEUMER Group. It makes it possible to handle inclinations of up to 60 degrees at a speed of 0.3 metres per second. "We developed a version that uses a belt instead of a chain for transporting the cells," says Andre Tissen.
More compact and more powerful
The basis is the well-proven BEUMER belt technology that is also used in bucket elevators. The belt is reinforced with steel wires and can be designed with different widths. In the feeding area the belt is - in case of instable kiln operation - protected by special deflector plates that divert the hot clinker away. "With up to 1,300 cubic metres of clinker per hour, the belt apron conveyor reaches higher conveying capacities than conventional apron conveyors with chain," explains Andre Tissen. This can be attributed to the higher running speed of up to 0.6 m/s. Angles of inclination up to 60° are possible. By using a belt you can basically avoid any wear and tear, which occurs frequently with a chain. You also no longer need to lubricate the system. And because of its more compact and lightweight design, this solution reduces the costs not only for the steel structure but for the entire project. The entire belt lies with its surface on the drive and return pulley, thus avoiding the unwanted polygon effect caused by the central chain. This ensures smooth operation and low noise emission, which means no additional impact on the system and the adjacent buildings.
The BEUMER belt apron conveyor is an optimal choice for system modernisations. Thanks to faster conveying speeds, higher quantities of material can be transported while keeping the existing conveyor frames and steel bridges. "One concrete example: A chain apron conveyor with a width of 1,600 mm and a centre distance of 131 metres weighs about 128 tons", explains Andre Tissen. "The steel structure weighs about 80 tons." An 800 x 131 metre belt apron conveyor capable of conveying the same capacity weighs only 90 tons - that is 38 tons less than the chain version. For the belt version, the net costs for the equipment are 25 percent lower and the steel structure weighs only 50 tons. A smaller drive unit can be used due to the reduced constructional size, which further lowers the running costs compared to conventional apron conveyors.
How to increase the capacity of belt bucket elevators Modernisations are an important aspect to consider for bucket elevators. A cost-efficient production requires bucket elevators with low investment costs, a long service life and easy maintenance. The buckets are mounted either to a belt or a central chain. Belt bucket elevators are best suited for fine-grained bulk material, because coarse material could fall between the bucket and the belt and damage the belt. Central chain bucket elevators, however, are designed to transport all types of coarse, hot or abrasive bulk material. The fine dust of the material causes wear and tear on the chains faster than on a belt. The user has to maintain the bucket elevators and replace the chains frequently. During repair, the operation has to stop. Additionally, replacement chains are very expensive. "This is why we developed the innovative high-capacity belt bucket elevators type HD," says Andre Tissen.
They are designed so that there is no more space between the individual buckets and the belt, where coarse material could otherwise get caught during the filling and scooping process. This way, the service life of the belt is considerably increased. The buckets are mounted firmly to the back of the belt by segments and bolts that were especially developed by BEUMER. BEUMER belts with wire-free zones are used for the heavy-duty bucket elevators just as with all BEUMER belt bucket elevators. The bucket mounting holes can be punched without damaging or cutting the steel wires. The traction forces of the belt are maintained to the full extent. The strongest belt that is currently available has a tensile load of 2,500 N/mm; the new BEUMER belt with wire-free zones has a tensile load of 3,300 N/mm. The special BEUMER bucket shape also allows for smoother running and therefore less noise generation. Depending on the material to be conveyed, BEUMER offers specially adapted buckets or mounts a dynamic bottom into the bucket elevator boot. This prevents wet and sticky material in the bucket elevator boot. When conveying highly abrasive material like clinker, these belt bucket elevators are a lot more durable than central chain bucket elevators.
These bucket elevators are already successfully used by many international cement manufacturers such as Dyckerhoff, Yamama Cement, HeidelbergCement, Holcim and Lafarge. At Lafarge, BEUMER retrofitted an existing bucket elevator with an HD belt bucket elevator in a cost-efficient and simple way. This became necessary because the kiln line was renewed and thus its capacity increased. This meant that the flow rate of the bucket elevator for the raw mill had to be considerably increased as well.
"For a long time, one of our German customers had the problem that coarse-grained material was falling between the bucket and the belt, damaging the belt," describes Andre Tissen. Along with the modernisation, the throughput as well as the running time per day increased, adding to this challenge. At Lafarge, the belt started to get porous already after two years of use. Initially, a chain bucket elevator was planned to replace the old belt bucket elevator. But then the manufacturer opted for the BEUMER HD technology instead. The requirement was that the existing bucket elevator housing including the drive unit should remain for the retrofit. This special BEUMER bucket elevator technology is used for example in raw mills and cement mills for the recirculation of material with grain sizes of up to 120 millimetres and a humidity level of up to six percent. Conveying capacities of more than 1,500 tons per hour can be reached.
Not too much, not too little - the optimal filling For filling cement into bags, BEUMER offers the BEUMER fillpac. This rotating machine fills any kind of cement into a variety of different types of bags. It can be individually integrated into already existing packaging lines and adapted to specific parameters. Specific weighing electronics are utilised to ensure weight accuracy of the bags. There are practically no rejects caused by too high or too low filling weights. The weighing unit communicates permanently with the filler neck via specific software. The automatic bag weight control determines the exact filling weight while filling. This way the system always achieves accurate degrees of filling. The packaging line works more efficiently now as it is no longer necessary to remove bags with an incorrect weight from the material flow. In addition, the quantity indicated on the bag always corresponds to the real volume.
This construction series comprises both air and turbine filling machines. The turbine process is the perfect solution for fine-grained materials such as cement. The result is filled bags which are compact and dimensionally stable so that the user is no longer required to vent them. Depending on the task, BEUMER offers BEUMER fillpac R with six, eight, ten, twelve, 16 or 20 spouts. The smallest version fills up to 1,800 50 kilogram bags or 2,250 25 kilogram bags per hour, the biggest version fills up to 6,000 50 kilogram bags or 7,500 25 kilogram bags, and all of the machines can be used for diverse bag types. The HDPE bag placer, an exclusive offering of BEUMER Group, enables dependable filling of HDPE bags. The filling impeller is characterised by its speed and the maximum material throughput. BEUMER Group also offers the turbine filling machines with inline design. The filling modules are placed next to each other for ready access, which makes them extremely easy to maintain. The inline filling machines are best suited for production environments with low throughput rates.
Onto the truck bed
With the BEUMER autopac, BEUMER Group has a system in its portfolio that loads cement bags directly from the filling machine onto the truck bed. Bags can be palletised automatically in stacked rows or patterns - without using pallets. Depending on the performance class, the system stacks between 2,400 and 3,000 50 kilogram bags per hour. The loading height, including the height of the truck bed, can be up to 3.5 meters. The user can freely select the formation of the layers depending on bag size and bag material.
The machine can load bags in double patterns of five or ten bags. In order to attain a high degree of stability for the whole load on the truck, and in order to optimally utilize the truck bed, two mirror-inverted layers are always palletised next to one another. The bags are flattened by the loading process using two stacked belt conveyors, which releases the air from the bags. After being positioned, the bags are also pressed by the loading head, which makes the stack more compact and more stable. The bag feeding lines can be adjusted to the installation conditions. Corresponding technical solutions are available for variable conveyor lines. Unlike on the systems where bags are suctioned and lifted, the bags are not deformed by the BEUMER autopac. In contrast with loading and palletising systems from other manufacturers, the BEUMER autopac is equipped exclusively with electrical drive units in its standard design. This means significantly less maintenance costs for the user. On vacuum drive units and hydraulic drive units, leaks that pollute the load and the system are inevitable. Additionally, the energy-intensive vacuum pumps and hydraulic drive units require additional cooling units, a fact that clearly increases the purchase and operating costs, as well as the energy consumption. The BEUMER autopac uses just 0.15 kilowatts per hour at full capacity. The drive units and machine parts are clearly arranged and easily accessible. This facilitates maintenance considerably.