Cleaning-up on Concrete Batching
First published in the December 2015 issue of Quarry Management
Stetter’s new automated concrete mixer cleaning system proves popular with batching plant owners
HighEfficient is the name of the new Stetter high-pressure wash-down system for concrete mixers, which uses pressurized water jets to thoroughly clean inside both pan-type and twin-shaft units. Cleaning out the concrete mixer on a regular basis is an important job in order to ensure the reliable production of high-quality concrete, but manual cleaning is both time-consuming and labour intensive, so there can be a temptation to skip intermediate cleaning, especially during busy periods.
A simple solution is to clean/spray the inside of the mixer rather like a dishwasher. Until recently, Stetter (the part of the Schwing Stetter concrete equipment company which specializes in truckmixers, batching plants and concrete recyclers) provided the option of having an automatic cleaning system from other manufacturers built into their batching plants. However, the cleaning capacity and reliability of these third-party systems did not meet customer expectations or Schwing Stetter’s quality requirements, so Stetter set about developing their own solution, resulting in the automatic HighEfficient cleaning system.
This new system thoroughly cleans the mixer within 20 min (for a full clean) using much less water than manual cleaning. Moreover, compared with manual cleaning, personnel costs are significantly decreased, downtime is reduced and employees are relieved from performing a physically difficult task. Additionally, the consistently high-quality cleaning process prevents premature wear that may result from insufficient cleaning and ensures continued system functionality. Regular intermediate cleaning, which takes 10min, avoids deposit build-up and helps reduce the cost of full mixer cleaning at the end of each working day.
According to Herbert Stiegeler from Schwing Stetter in Germany, the new system is becoming increasingly popular. He said: ‘We have sold 40 or 50 units since we implemented the first prototype in 2013 and even though we have only just started to publicise this new system, it has fast become standard technology on all new batching plants sold in Europe. Many customers are choosing a Stetter concrete plant because of the HighEfficient cleaning system.’
Three quarters of the new systems have been incorporated in new Stetter batching plants with the remainder being retrofitted into existing plants, around 50% of which are older Stetter plants.
Cleaning heads
Depending on the size of the mixer, the HighEfficient cleaning system from Stetter has four or five cleaning heads arranged in a set pattern embedded in the mixer cover. The 3D cleaning heads are used sequentially during the cleaning cycle, ensuring each twin-jet nozzle head receives full power from the double-pump unit. The combination of high water pressure and flow ensures that persistent concrete and cement residues are removed effectively. The splash zone within the mixer can be adjusted to, for example, prevent water gaining entry into the cement outlet. In addition to the rotation of the cleaning heads, the end of each head also rotates with its two jet nozzles, ensuring optimal surface coverage.
High-pressure pump unit
Each of the two 11kW pumps in the high-pressure double-pump unit is equipped with a dry-run protection pressure monitor to prevent the unit from starting without water. When in operation, the system provides a constant flow of water (100 litres/min) at 100 bar pressure. The high-pressure pump unit has a separate coax valve for each cleaning head and an additional pipeline outlet to which a hand lance can be connected for manual cleaning work. The supply line to the pump unit is equipped with a dirt filter and a manual three-way valve to drain the pipe for frost protection.
Control
The HighEfficient cleaning system is intuitive to use and easy to operate. The desired cleaning programme (full or intermediate cleaning) can be selected and started via a large-format touch-screen display, and the duration and intensity of cleaning can be adapted according to the requirements of the mixing plant. The display also provides graphic information about the various stages of mixer cleaning and permits quick retrieval of system data and selected settings to allow real-time alterations to the parameters. The cleaning control can be integrated into existing mixing plant controls from Stetter or other providers.
For more information visit: www.schwing-stetter.co.uk
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