quadropol® - vertical roller mill

thyssenkrupp is one of the few full-range suppliers for the cement industry – from individual machines, all the way up to complete cement plants, and this since decades. The market requirement is easy to define. Present kiln lines have capacities of up to 10,000 tons per day. Kiln lines of 12,000 tons per day were already built by polysius® technology.

polysius provided the latest equipment technology for the plant and as a result the Oruro works is one of the most modern cement facilities in Latin America.

International Cement Review January 2020

„The making of Oruro“ by Cementos de Bolivia and PEC Consulting Group, USA

The quadropol® - advantages at a glance

  • Lower construction costs

  • Easier maintenance

  • Lowest level of vibration (< 2.0 mm/s)

  • Highest level of digitalization

Extract of our references
Cemento de Bolivia, Cement Bolivia, 3000 tons per day plant incl. QMR² and QMC²

Cemento de Bolivia

Cementos de Bolivia ordered a 3,000 tons per day kiln line, successfully commissioned in 2019. This was an EPC contract to the German-Spanish polysius-Imasa-Valoriza consortium. The contract included a QMR² 38/19 for raw grinding and a QMC² 45/23 for cement grinding.

Cemento Progreso, Guatemala, 4500 tons per day plant incl. QMR² and QMC²
Cemento Progreso, VRM, Vertical Roller Mill, quadropol, QMR², QMC²

When developing and designing the machinery for the cement industry, it is necessary to create a technically viable solution to meet the market requirements. Besides a general feasibility study, and further development as well as optimisation of the design, this calls for an intelligent design approach encompassing. This includes a simple mode of operation as well as economic and desired product aspects.

Today the capital expenditure (CAPEX) for plant operators is generally very high and it is thus only natural that high availabilities need to be achieved. Vertical roller mills are an essential part within the production process for grinding raw material (QMR²), coal (QMK²) and increasingly binding agents or slag (QMC²/QMS²).

vertical roller mill, inspection roller mill, roller unit

At the end the cement quality is important to serve the market. Finally, the raw mill product is the supplier for the kiln, means also responsible for the clinker quality. A technical reliable solution within the production process includes our sepol® high efficiency separator to ensure the desired product fineness for all applications. For raw grinding our new developed HDZX double cyclones are part of the technical solution and includes latest process know-how.

The spotlight has also turned on operating and maintenance costs (OPEX). The energy consumption of a mill, as well as of the entire grinding system or section, plays a significant role in decisions made by plant operators. Maintenance work, which includes inspection, servicing, repairs and improvement, is a cost driver and needs to be taken into account.

In the last years, thyssenkrupp has successfully continued stepwise the development process for the quadropol® vertical roller mill concept. This compact and modular conception includes the latest market requirements regarding compact plant layout, efficient operational process, reliable machine design and reduced unscheduled down time. Tailor-made solutions with interchangeable parts are also available. The topic digitalization is being pushed ahead and part of the current design.

polysius® grinding plants – a holistic approach

The development and, in particular, the enhancement of the quadropol® concept incorporates the requirements of the market and is subject to a continuous development process.

Cemento Progreso, Guatemala, 4500 tons per day plant incl. 2 x QMC² 51/25
Cemento Progreso, Guatemala cement plant, quadropol
Simulation tool for maintenance sequences

The roller unit has a very compact design, is fully pre-assembled in the thyssenkrupp proprietary workshop and is the final component to be installed. The vertical roller mill design calculation considers efficient comminution, longevity and highest reliability. The reduction in mechanical components in itself decreases here the probability of failures.

Assembly and adjustment of the mill components is reduced to a minimum in order to shorten the erection time and save costs. The weight of the four preassembled roller units of a medium sized mill is approx. 50 % of the total weight of the mill components and separator. This lowers the total effort regarding assembly, alignment, welding and reduces the total cost of erection. At the same time the erection process will be faster.

The hydraulic system is also smart and compact; one hydraulic unit serves for the four roller units. The grinding force for comminution is generated solely by one hydraulic cylinder per roller unit. This concept also requires only one piston accumulator to act as the spring system. The fixed bearing is maintenance-free, and although the roller bearing is located in the mill, it is fully capsuled without any shaft sealing inside the mill. As no dust can get in, there is no longer any need for a sealing air fan. Accessibility is excellent and it is possible to carry out small maintenance work easily without the necessity to remove the roller unit. The design and working principle or operation principle of the mill are shown here in an animation.

In particular vibrations in the grinding plant are of crucial importance. The using of reinforced concrete pylons for the roller units has a big benefit, apart from easier civil work and cost, the vibrations level is much lower due to the good damping characteristic. During unstable operation all loads are transmitted to the foundation in vertical direction. Components such as the stopper are arranged in an intelligent way, the stoppers are arranged in the effective direction of the hydraulic cylinder. The vibrations need to be avoided in order to protect the mechanical components of the grinding plant. The focus here is not on the vibrations of the gear unit base, as these are approx. 0.5 mm/s in vertical direction only. Rather, it is important to detect the vibrations caused by the grinding process. For this purpose, a sensor is installed in each tension frame of the roller units, namely at the level of the grinding bed. In nearly all installed mills, the vibration value due to the efficient grinding process and foundation solution is less than 2 mm/s in horizontal direction and this sets still the benchmark. The low vibration level demonstrates the smoothness of the running mills and the operational continuity as well as longevity

roller units pre-assembled, vertical roller miller, quadropol

The design philosophy is for all applications the same and part of the holistic approach. For coal or pet coke grinding a safety concept must be considered to protect persons and machinery who work in hazard areas. ATEX is therefore a non-negotiable point in the process installation. All directives need to be carefully fulfilled and part of the design of our coal mill QMK².

Why choosing the quadropol® concept?

  • Compact plant arrangement

  • approx. 50 % pre-assembled of mill & separator

  • Lowest down time due to mechanical simplification

  • Less assembly, less alignment, less welding results in reduction in total costs

  • Simple hydraulic system with only one piston accumulator, one roller bearing, no confining air

  • Roller lubrication with one lubrication pump, return flow by gravity

  • Lowest market vibration level < 2 mm/s (measured horizontal at location of comminution)

  • Vertical roller mill gearbox forces only in vertical direction due to arrangement, vibration level < 0.5 mm/s

  • No extensive scaffolding necessary for maintenance work, considering OSH regulation

  • Changing roller tyre within two shifts on pylon

  • Highest mill compound availability and reliability

  • Efficient grinding – low specific power consumption

  • System Monitoring and Advanced Mill Controller implemented

  • Stable operation and process monitoring/control

  • Digitalization incl. AMC and state-of-the-art data analysis

  • etc.

This state-of-the-art equipment enables the staff to monitor and control all process variables in real-time. (...) As shown the plant is able to deliver a stable process and supply a high-quality product.

International Cement Review January 2020

„The making of Oruro“ by Cementos de Bolivia and PEC Consulting Group, USA

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