Polysius
Effective protection
against false air.
polysius® Coarse Feed ValveEffective protection against false air.
The airlock upstream of the mill. It keeps false air out of a negative-pressure grinding process while coarse-grained material is continuously fed and passed onwards – for raw material, slag and coal, at grain sizes from 0 to 200 mm.
- Grain size
- 0 to 200 mm, depending on the design
- Valve types
- Two — for raw material and slag, and for coal
- Construction
- Low overall height and extreme robustness
- Sticky material
- Heatable ducts prevent incrustations on the vane rotor
- Spare parts
- Also for plants engineered and erected by third parties
The Task — Protection Against False Air
Coarse feed valves serve as airlocks and as continuous feeding units for coarse-grained materials. They minimize the effect of false air in a grinding system operated under negative pressure and permit continuous further conveyance of the materials. The conveyed material is supplied to the feed valves at a controlled rate by, for instance, belt conveyors, bucket elevators, continuous conveyors or deep bucket conveyors.
This type of feed valve is primarily used upstream of roller mills and ball mills for supplying coarse-grained bulk materials such as limestone and coal, with a particle size range of 0–200 mm depending on the size of feed valve involved. The feed valves are provided with heatable channels to prevent caking during the conveyance of moist or very sticky materials.
DISTINGUISHING FEATURES
Low overall height — a real constraint when retrofitting into an existing building
Extreme robustness and a long service life
Heatable ducts: when moist or highly sticky materials are used, incrustations on the vane rotor are avoided
Impact table protects the vane rotor — the feed material falls onto it first
Wear protection plate on the sealing strips at the vane rotor and on the cylindrical housing section
Low-noise operation
Main Components
Numbering follows the callouts on the product photograph used on the page.
The heatable ducts that prevent incrustations on the vane rotor with moist or sticky material
Where the regulated feed from the conveyor or bucket elevator enters
With motor and safety coupling; the coupling disconnects the motor from the gear unit in the event of a blockage
The discharge into the mill feed
From size III onwards
Made of wear-resistant steel; sealing strips at the vane rotor and the cylindrical housing section are made of wear protection plate
Product Range
We offer two different types according to the application in question: on the one hand a coarse feed valve for raw material and slag, on the other hand a coarse feed valve for coal. Alongside them, the polysius® spring-plate cell airlock covers air sealing and dosing tasks across a far wider temperature and throughput range.
| Raw material & slag | Coal | Spring-plate cell airlock | |
| Application | Upstream of roller mills and ball mills, for coarse-grained bulk materials such as limestone | Coal grinding systems | Air sealing and dosing tasks; particularly suited to material feeds in preheating systems |
| Key figures | Grain sizes 0 to 200 mm depending on the design | Grain sizes 0 to 200 mm depending on the design | −40 °C to +450 °C; throughput from a few m³/h to 1,000 m³/h |
| Design | Low overall height, extreme robustness, heatable ducts, impact table | Same airlock principle and robust construction, heatable ducts | Robust cast design, in successful use for decades |
| Service note | Wearing parts and spare parts easily replaced | Wearing parts and spare parts easily replaced | Spare parts service for existing airlocks; substitutes for other existing airlocks can be offered in the spring-plate design |
Service & Maintenance
Our coarse feed valves have a robust design and a long service life. To protect the vane rotor, the feed material first falls onto an impact table. The sealing strips at the vane rotor and the cylindrical housing section are made of wear protection plate. To make maintenance easier, there are inspection covers and cleaning ports in the housing. The drive has a safety coupling in order to disconnect the motor from the gear unit in the event of a blockage.
| Access | Inspection covers and cleaning ports in the housing; an inspection cover is provided from size III onwards |
| Wear protection | Impact table protects the vane rotor; sealing strips and cylindrical housing section made of wear protection plate; wearing parts and spare parts easily replaced |
| Blockage protection | Safety coupling in the drive disconnects the motor from the gear unit in the event of a blockage |
YOUR SERVICE ADVANTAGES
False air in the grinding process is minimised
Continuous delivery of the feed material
Extreme robustness
Depending on the design, for grain sizes from 0 to 200 mm
Easy installation
Wearing parts and spare parts can easily be replaced
Low-noise
Heatable ducts avoid incrustations on the vane rotor
Note: the flyer's advantage list reads “Easily installation”. This has been corrected to “Easy installation” on the landing page.
Replacement & Modernisation
| Measure | Effect | Condition |
| Substitute an existing airlock | In addition to the spare parts service for existing airlocks, substitutes can be offered with the spring-plate airlock design | Also for airlocks from other manufacturers |
| Fit where headroom is tight | The low overall height is often the deciding factor when a machine has to go into an existing building | Easy installation |
| Add heatable ducts for sticky feed | Avoids incrustations building up on the vane rotor — the usual cause of falling throughput and rising drive load | Hot gas inlet and outlet on the housing |
| Renew the wear protection | Restores the seal without replacing the machine | Wearing parts and spare parts can easily be replaced |
| Move to the right valve type | A change of feed material can be a reason to change the valve | Two types available by application |
| Airlocks for preheating systems | Spring-plate cell airlocks work between −40 °C and +450 °C at throughputs up to 1,000 m³/h | Robust cast design, in use for decades |
The airlock upstream of the mill: coarse material continuously fed and passed onwards — with the effect of false air minimised.