proposed equipment for flotation cleaning of high poly containing pulp

Proposed Equipment Proposed Equipment for Flotation Cleaning for Flotation Cleaning of High Poly of High Poly Containing PulpContaining Pulp

Concept:

D K Singhal

[email protected]

IntroductionIntroduction

� With more and more cup stock, milk cartons and similar wastepaper grades in market for recycling, we need good equipment for handling of the pulp that equipment for handling of the pulp that contains high amount of poly.

� This presentation presents concept of Float-Pro, a flotation based poly removal equipment.

2Proposed Equipment for Flotation Cleaning of High Poly Containing Pulp, July 2014

Existing AlternativesExisting Alternatives

� Screen plate in Pulper

� Drum Screen

� Vibrating Screens

� Pressure Screening� Pressure Screening

◦ Hole

◦ Slot


Screen Plate in Screen Plate in PulperPulper

� This option is possible only in selected pulper types.

� Some manufacturers have developed pulper add-on units (e.g. Contaminax, pulper add-on units (e.g. Contaminax, Poire etc.) which are also working fine.

� For bigger poly pieces, these are extremely good.

� However, small poly particles remain with the pulp.


Drum ScreenDrum Screen

� Here, the operating consistency is much lower.

� Drum screens are very efficient, yet some fine poly still remains with the pulp which fine poly still remains with the pulp which needs to be removed.


Vibrating ScreensVibrating Screens

� As far as cleaning is concerned, vibrating screens are very efficient.

� However, these are not suitable for large production rates.production rates.


Pressure ScreensPressure Screens

� Pressure screens (both hole and slot type) are good and efficient.

� Still, they have a limitation on contamination, and a too heavy poly contamination, and a too heavy poly percentage in inlet stream can result in clogging of screen basket.


Present ObjectivePresent Objective

� With existing systems, if the poly content is limited to 10-12% or a little higher in water paper, there is generally no problem.problem.

� But in case poly content is increased, it becomes often necessary to reduce the production rates to efficiently clean the pulp.


Present ObjectivePresent Objective

� Basically, there lies a gap between coarse screening (pulper cleaning/drum screening etc.) and fine screening (pressure screens).screens).

� We need some equipment in between the two so that the reliability of the whole process remains good.


ApproachApproach

� In the proposed approach, the use of following properties is suggested-

�Poly is generally lightweight (0.91-0.93 sp. gr.), and slowly floats in pulp suspension.

�The shape factor of poly results in more drag and �The shape factor of poly results in more drag and hence retards easy removal due to low density.

�Fine air bubbles in the suspension tends to attach with different suspended particles, thus further reducing their apparent specific gravity.

�Bigger air bubbles move up in the suspension at a faster rate and cannot get attached to pulp fibers in the suspension.


Equipment DesignEquipment Design

� The cleaning equipment is a rectangular tank shaped structure, with different partitions in between to allow having different zones.different zones.

� For ease, the equipment has been named as Float-Pro.

� A schematic of the same is given on the next sheet.


Schematic of FloatSchematic of Float--ProPro


DescriptionDescription

� As clear from the schematic, the unit looks like a tank with partitions to create different chambers.

� The pulp enters the first zone, where a coarse air diffuser (ADP-M) mixes the coarse air diffuser (ADP-M) mixes the pulp to create turbulence and uniform mixture.

� From the bottom of separator plate S0, the pulp enters ‘Zone-1’ where the poly based contaminants float upwards.


ConstructionConstruction

� Float-Pro looks like a rectangular tank. It can be either fabricated in SS, epoxy coated carbon steel or casted in RCC.

� The top of Float-Pro is open to allow � The top of Float-Pro is open to allow easy removal of poly.

� Separator plates S1, S2 and S3 have small openings/perforations at bottom that allow pulp to go to next zone.



� In ‘Zone-1’ pulp gets some time and poly contamination moves upwards. The pulp with lesser poly contamination moves to ‘Zone-2’, and in the process passes through ‘ADP-1’, where more air is injected in the ‘ADP-1’, where more air is injected in the pulp.

� Air from ‘ADP-1’ does two jobs. First to get attached to poly so that its floatation in the next stage is faster, and second keeping away the separated poly on the top.



� Similarly, pulp passes through ‘Zone-2’ and ‘Zone-3’ and most poly is effectively removed from pulp.

� A drain valve at bottom is provided to � A drain valve at bottom is provided to empty out the unit if required.

� The floated poly can be removed by robotic or hydraulic arm grabber, similar to one as shown in next slide.


ADP DesignADP Design

� Thicker, larger poly floats first. That is why air diffuser pipes ADP-1,2,and 3 are designed in such a way that the size of air bubble decreases in each subsequent stage.stage.

� So, you get larger poly in Zone-1, and smallest poly in Zone-3.

� However, the bubble size should be significantly higher than the fiber size in any stage.


Operational ParametersOperational Parameters

� The size of unit is a function of operating production rate and consistency, which should be less than 1%.

� Minor increase in production rate and � Minor increase in production rate and hence operating consistency does not result in significant impact on performance, except that the poly removal efficiency decreases slightly.


Water HardnessWater Hardness

� A soft water promotes longer bubble life, and makes the floated poly very bulky. That is why it is not desirable. Addition of suitable chemicals for increasing water suitable chemicals for increasing water hardness, or defoamers will be better for the system.


� I’d like to hear from machinery suppliers or innovative paper mills that they have developed an equipment on this concept, and that is working fine.and that is working fine.

Thank You.


About the Author:

Born in 1968, D K Singhal is B.E., M.E. (Pulp & Paper, 1993) from Deptt. of Paper Technology, University of Roorkee (now IIT, Roorkee). He is a Certified Energy Auditor and Chartered Engineer also.

With nearly 7 dozen publications, he has emphasized on development of low cost technologies and management practices for quality and profitability improvement. With publications on slideshare.net, energymanagertraining.com and paperonweb.com, he has been constantly contributing to IPPTA (Indian Pulp & Paper Technical Association). He is also serving IPPTA as a member of Editorial Board. Board.

An initiative by D K Singhal, a cyber campaign initiated against unjustified targeting of paper industry by “Idea” mobile, in their “Sirjee” advertisement campaign, after which this advertisement was taken off air.

He also moderated a Yahoo group, “PaperTechnology” with nearly 360 members from India and abroad to discuss problems related to pulp & paper making for five years.

He can be contacted at [email protected]
