A variety of sorting and material separation processes are used to prepare recyclable materials and make them available for subsequent utilisation or recycling. Suitable conveyor technologies link the individual plant components and ensure that the material flows are optimally controlled.
In order to offer a holistic portfolio of solutions, GÜNTHER operates as both a component supplier (through to projects with more than 100 aggregates) and also as a general contractor for large plants. The services offered range from consulting, project planning and engineering through to the manufacture of the components at its own production facilities (incl. control programming and visualisation) and installation on-site. And the services are rounded off by customer training and the joint approval and acceptance of the plant. Alongside “off-the-shelf” mobile and stationary solutions, GÜNTHER has successively expanded its expertise in the design and construction of customised plants.
Even if conveyor technology is mostly “just” a means to an end, it nevertheless holds a position of central importance for delivering materials to the star screen or SPLITTER spiral shaft separators. This technology not only connects the components to one another but is a relevant part of the entire process. Factors such as the design (type of belt), running speed and PLC-controlled synchronisation ensure that the individual components of the plant are supplied with material – constantly and at the required dosage. In this respect, intelligently arranged conveyor systems are decisive factors for the efficiency of the entire process and the high-grade quality of the end product.
The importance of using different conveyor technologies in a processing plant will be illustrated using the example of the plant project “Biomass processing for the generation of biogas” for Biothan GmBH based in Fulda.
Biothan GmbH operates a highly innovative plant for generating bio natural gas from biogenic waste sourced from the local region. Organic waste (commercial waste, manure, household organic waste bins) is used for the generation of energy by refining the raw biogas created during its fermentation to produce bio natural gas in the final processing stage. The residue from the fermentation process is used as fertiliser in solid or liquid form in the agricultural sector, while it is used as compost for gardens and woodlands when enriched with green waste.
Challenges
The customer was looking for a solution for the processing of solid bio waste (from household organic waste bins) and green waste into a fermentable form. Furthermore, the processed material also needed to be made available for the subsequent feeding of the digesting plant – consisting of two plug-flow fermenters.
The challenge was to produce an input material that was as far as possible free of impurities and had a grain size of up to 60-80 mm which could be constantly fed into the fermenters at the ideal dosage.
The processing plant also needed to be as compact as possible and set up in the waste reception hall in a space-saving manner.
Solution
The following concept was implemented at Biothan GmbH (overview):
1. The starting material was firstly shredded (1).
2. The shredded material was then fed into a stationary MULTISTAR 2-SE (3) screening system via a troughed conveyor (2). It was separated here into 2 fractions:
- The so-called oversized grain (> 60-80 mm) was discharged into a hopper via a discharge conveyor (4) and partially fed back into the separation cycle.
- The fine grain is then processed further as usable materials with the required maximum grain size of 60-80 mm.
3. Foil and other impurities are filtered out using a wind sifter (5).
4. The fine grain is output via a swivelling stockpile conveyor (6), which feeds a concrete hopper for stockpiling the material (7).
5. The stockpile conveyor is fitted with an ultrasonic sensor at the end that moves the conveyor to the next free space as soon as the cone of discharged material reaches a defined height.
The finished cone is then distributed across the entire surface of the hopper using a hall crane. Amongst other things, the hopper serves as a buffer tank to stockpile the input material and guarantee a constant supply to the fermenter 365 days a year.
6. For feeding the two plug-flow fermenters, Anlagenbau GÜNTHER supplied a TAKER TL-12-18 receiving station (8), which doses the input material via a discharge conveyor (9) onto a reversible distribution conveyor (10) and thus ensures the optimal feeding of the fermenters. Both conveyor belts were enclosed because the process takes place outside.
The TAKER is filled using the hall crane. The TAKER stands on a weighing mechanism with four weighing cells as part of the electronic filling control system.
Requirements for the conveyor technology
Five conveyor belts with different designs were installed in total for the “Biomass processing” project:
1. A troughed conveyor for holding the shredded material and feeding the material into the MULTISTAR 2-SE separating plant
2. A HD-conveyor for discharging the oversized grains
3. A swivelling, sensor-controlled stockpile conveyor for discharging the usable material and feeding the concrete hopper
4. A troughed conveyor for discharging the material from the TAKER L3 receiving station
5. A HD-conveyor in the form of a reversible distribution conveyor for feeding the two plug-flow fermenters
The conveyor technology provides a control function for the entire process. The ideal design of the individual types of conveyor and the procedural synchronisation of the individual conveyor components using optimised PLC-programming are essential prerequisites for achieving the greatest possible efficiency in the production process.
Customer feedback
Biothan is extremely satisfied with the functionality of the plant. “Operation of the plant is constant and stable. The arrangement of the conveyor technology, in particular, ensures that all components are ideally synchronised with one another. As a result, both fermenters are supplied with raw material with the required properties and in the required quantity 365 days a year”, concluded Managing Director Sebastian Tews.