The Venturi is a lower Specific Energy Design for Good Fiber Quality. Its design principle enables a proprietary bar and groove configuration that creates a turbulent flow of steam to delicately break down chips and gently treat separated fibers. The design is especially unique because it enables lower specific energy consumption and optimized fiber characteristics simultaneously.
Venturi/CD Refiner Fillings
- Constant Angle
- Single or Multizone
- Steam Grooves
- Strategically Placed Dams
- Simultaneously changing bar, groove and depth dimensions
- Curved bar edges for longer cutting edge length
- Steeper angle pattern design
- Bar and groove shape creates strong, non-breakable refining bars
Advantages of Venturi
- Improves Steam Flow
- Reduces Plate Gap Pressure and Temperature
- Allows Steeper Angle Unidirectional Bar Layout
- Enables Higher Production Levels to be used for Enhanced SEC Savings
- Boosts Energy Efficiency
- Lower specific energy requirements for excellent fiber quality
- More gentle disintegration of chips and fiber bundles results in longer fibers with less shives and a lower amount of fines
- High turbulence of steam and fiber flow in the grooves minimizes carbon and pitch build-up
- Longer plate life due to improved utilization of refining surface
- Suitable for all raw materials
Key Features of our Venturi Design:
- Non-dammed design for easier steam evacuation
- Lower pressure/temperature in the plate gap
- Improved refiner stability
- Large open volume in the grooves
- Reduced carbon/pitch build-up
- Unidirectional design for optimized fiber characteristics
- Pumping—low specific energy
When comparing, the Venturi inlet zone will break down chips into usable fiber fractions without generating fines while standard subsurface dams in the inlet will generate a high level of fines which increases resin requirements when making fiberboard.
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Refiner Plate Design
Different refiner applications require different plate designs as system optimization is undertaken.
Fiber treatment, hydraulic capacity and breakage resistance are three critical parameters that must be considered when designing and applying low consistency refiner plate patterns.
A paper mill can optimize its low consistency refining operations on two fronts:
- Monitoring and eliminating as many detrimental hydraulic, mechanical and process conditions as possible.
- Ensuring that the proper plate designs and alloys have been selected.
By working together with our papermakers, J&L Fiber Services seeks to develop strategies to optimize the unique needs and performance of a particular paper mill.
Given the difficulties of being able to control all of the many process variables, refiner plate design becomes extremely critical. The key design parameters, relative to delta P (refiner pressure control) are: groove depth, groove profile, number of bars & total pumping angle.
The intensity of refining that is required will determine the bar width/groove relationship,or pitch. However, groove width should be altered to optimize the throughput rate. This can be done without changing the pitch or intensity by altering the bar width correspondingly.
A special caution when altering groove depth for flow control: While no appreciable negative effect will occur when groove depth is reduced for lower flow rates, increasing groove depth poses some risks. First, it is less efficient than increasing groove width. Second, it can have a negative effect on energy efficiency, because increasing groove depth increases the no-load energy required to spin the rotating element in the stock slurry.
Bar angle is significant to the extent that it affects the delta P and is a tool for hydraulically balancing the refiner.
The relatively infrequently used practice of running the low consistency refiner plates in the holdback position can effectively compensate for low flow conditions which are detrimental to fiber quality, plate life, etc. During holdback, the intersecting bar angle between the rotor and the stator is moving towards the center line of the refiner rather than towards the periphery of the disc, as in pumping position. Holdback will increase the turbulence in the grooves and the plate gap.