The Rotorrake is a robust in-line single-shaft grinder for the coarse processing of solids.
Blades and counter-cutting plates are mounted alternately on the carrier shaft. The counter-cutting plates fixed to the shaft are constantly cleanedby the rotating blades. The blades are driven by the rotation of the shaft. The range includes various sizes of the Rotorrake with capacities up to 800 m³/h. It is designed to grind very coarse solids and fibrous matter. The Rotorrake copes where other grinders run into trouble.
Components
Parts of the Rotorrake grinder
| 1 | Quick-release cover | The quick-release cover gives fast access to the grinder chamber for replacing any part in contact with the medium. |
| 2 | Blade holder and counter-cutting plates | Blades and counter-cutting plates are mounted alternately on the carrier shaft. The counter-cutting plates are fixed so that they cannot work loose. By turning the plates and blades you can use every cutting edge. |
| 3 | Grit collection chamber | In solids separation mode the blades rotate so that non-grindable particles fall into the grit collection chamber. |
| 4 | One-piece housing | The grinder housing can be made of high-grade grey cast iron or stainless steel. |
| 5 | Drive | Three drive options are available: a motor with a flat gearbox, a hydraulic motor, or a free shaft end on a support bearing. |
Operating principle
The Rotorrake is a single-shaft grinder for processing coarse solids with an effective solids separation function. Because of the effectiveness of its grinding action, the Rotorrake can be used at treatment works to process fibrous matter. Liquid with solids flows through the angled counter-cutting plates. Solids caught by the plates are cut by the rotating blades. The liquid then flows on together with the ground solids. Material that is too coarse or cannot be ground collects in the grit chamber.
Capacity up to 800 m³/h
Reversible flow direction
Advantages of the Börger Rotorrake
Remarkable power
The Rotorrake can process even the coarsest solids and fibrous matter that other grinders cannot handle.
The grinder is built to the requirements of the particular duty it has to perform.
The Börger Rotorrake can be adapted to any duty. It can be installed in a production line, where it works as a fixed unit. Mounted on a trailer together with a pump, it becomes a mobile unit.
To reach the working parts of the grinder all you have to do is remove the quick-release cover and undo the central bolt. The Rotorrake is built on the MIP principle (Maintenance in Place). It is as convenient and simple to service as all equipment made by Börger.
Product range
With or without a grit collection chamber
Depending on the application, the grinder is installed with or without a grit collection chamber (16 l or 150 l). If the operating situation
changes, the grit chamber can be altered, replaced or removed.
Various installation options
A wide range of options
Rotorrake grinders come in a great variety of versions. The direction of liquid flow can be changed even after the unit has been installed (a short list is given below).
Rotorrake pure — installation example
- without a stone trap
- Flow direction right to left
- The medium contains no solids that cannot be ground
Rotorrake plus — installation example
- with a 16 l stone trap
- Flow direction left to right
- Solids that cannot be ground automatically fall into the stone trap
Rotorrake plus 150 — installation example 1
- with a 150 l stone trap
- The medium enters the Rotorrake from the right through the stone trap
- Solids that cannot be ground stay in the stone trap
Rotorrake plus 150 — installation example 2
- with a 150 l stone trap
- The medium enters the Rotorrake from the right through the stone trap
- Solids that cannot be ground stay in the stone trap
Control system
Built to your requirements
Our electrical engineering department can build and program a control system exactly to your requirements.
Overview and choice of version
- A high level of safety thanks to reversing control (time-based or load-based reversal)
- Reversal parameters are easy to set
- External operator control via smartphone, WLAN or DSL is possible (remote access by Börger specialists is also available)
- Collection of operating data
- Simple entry and administration via touchscreen
- Modular solutions and control cabinets
- Integration into an industrial network (Profinet, Profibus and others)
- Starting under high and very high load is possible
- and more
Application examples
Rotorrake Grinder
We have been building Rotorrake grinders specifically for particularly demanding duties since the late nineties. The equipment is striking in its robustness and reliability. The Rotorrake is excellent for processing very coarse solids and fibrous «matter».
The versions presented here will give you an idea of what our engineering can do.
Pumping station
The same problem kept recurring at a pumping station and kept breaking the pumps. Hard and soft solids settled in the pumps and obstructed the pumping of wastewater.
The station's operator tested various grinders from different manufacturers. Processing solids this coarse proved a problem for all of them. The operator then tested the Rotorrake, developed specifically for coarse solids. The organisation's specialists were struck by its effectiveness. There were no failures or breakdowns at all while grinding coarse solids. Once the Rotorrake was installed at the pumping station, no further problems with solids occurred. The customer was completely satisfied with the Rotorrake.
Technical specifications
| Grinder | Rotorrake 6000 |
|---|---|
| Medium | Digested sludge |
| Capacity | 50 m³/h |
| Speed | 100 rpm |
Circulation of the digester mixture
At a treatment works, fibrous matter in the sludge caused problems again and again. The grinders in use could not cut thick matter into many small pieces. As a result the centrifugal circulation pumps in the bioreactors kept clogging. The treatment works operator tested the Börger Rotorrake. The Rotorrake is a powerful grinder designed for installation in a production line. Blades and counter-cutting plates are mounted alternately on the carrier shaft. The Rotorrake was tested intensively over a long period. During testing there were no problems with the grinder or the centrifugal pumps. After the test no signs of wear were found on the blades or the counter-cutting plates.
Technical specifications
| Grinder | Rotorrake |
|---|---|
| Medium | Digested sludge |
| Capacity | 100 — 200 m³/h |
| Speed | 200 rpm |
Spreading liquid manure on fields
A contractor carrying out agricultural work for farmers needed a pump and a grinder to mount on a truck with a liquid manure tank. The company owner's idea was that this vehicle would collect manure from farms and take it to the field or to a biogas plant. The pump was needed to fill the tank and to feed the manure into the spreading system. To avoid blockages in the spreading system, it was decided to install a grinder upstream of the pump.
The choice fell on the Börger EL 1550 pump and the Rotorrake 9000 grinder. Besides compactness, the customer's decision was influenced by the high quality of the equipment and, as a result, the long service life of Börger machines. The company needed to keep downtime of the tanker vehicle to a minimum.
The customer was very satisfied with the pump and grinder combination. Thanks to the ease of service, long service life and high capacity of Börger equipment, the efficiency of this vehicle increased considerably compared with trucks at companies using other manufacturers' equipment.
Technical specifications
| Börger | Rotary lobe pump + Rotorrake grinder |
|---|---|
| Medium | Liquid manure with solids |
| Temperature | 20° C |
| Capacity | 9000 l/min |
| Pressure | 1 — 2 bar |
Mobile container filling unit
A company processing liquid manure needed a container filling station. Because the pumped medium often contains solids that can block the distributor, the customer required the mobile station to include both a pump and a grinder. The supplier's ability to build a fully equipped station played an important part in the choice.
The organisation decided to buy a Börger container filling station. Besides the powerful pump and effective grinder, the customer's decision was influenced by the high level of service from Börger GmbH. The unit was designed individually to meet all the customer's wishes.
The pump is driven through the tractor's power take-off. Rotation is transmitted to the grinder shaft from the pump's second shaft by a chain drive that needs no complex maintenance. A slip clutch ensures safe operation. The filling device can be adjusted for height using the tractor's hydraulics. The boom swivels manually through 360°. The customer was very satisfied with the custom-designed filling station.
Technical specifications
| Börger | Rotary lobe pump + grinder |
|---|---|
| Medium | Liquid manure and waste |
| Capacity | 9000 l/min |
| Pressure | 1–2 bar |
| Temperature | 20 — 40 °C |
Silage
At a two-stage biogas plant there were constant problems with a progressing cavity pump that kept clogging. The pump was installed between the primary and secondary digester. The biogas plant processes maize (millet, grass, rye) and dry chicken manure.
The customer decided to buy a Rotorrake grinder. It was installed on the suction side of the progressing cavity pump.
The operator is satisfied with the grinding effect of the Rotorrake. The pump no longer clogged, and the long service life and maintenance-friendly design impressed the customer greatly. He is now considering using other Börger equipment in his plant.
Technical specifications
| Börger | Rotorrake Grinder |
|---|---|
| Medium | Substrate in a biogas plant |
| Capacity | 12 m³/h |
| Speed | 300 rpm |