High consistency re-pulping method, apparatus and absorbent products incorporating recycled fiber

Patent metadata

Field	Value
Publication number	US-11486089-B2
Application number	US-202017062789-A
Country	US
Kind code	B2
Filing date	Oct 5, 2020
Priority date	May 31, 2017
Publication date	Nov 1, 2022
Grant date	Nov 1, 2022

Abstract

A method of pulping wastepaper includes providing a pulping vessel with a rotor and at least one flow sensor adapted to measure slurry flow within the pulping vessel. The pulping vessel is charged with wastepaper and water to form a slurry, the amounts of wastepaper and water being present such that the slurry has consistency in the range of from 10% to 30%. The wastepaper charge in the pulping vessel is pulped at a pre-selected power level while monitoring poloidal slurry flow in the pulping vessel; and from time-to-time, water may be added to the pulping vessel when the poloidal flow falls below a predetermined lower threshold flow value in order to reduce viscosity and thereby restore poloidal flow within the pulping vessel. Doppler velocimetry is a preferred method of monitoring pulp flow. In a particularly preferred construction the rotor has a variable power drive. The inventive method is especially useful for making high quality, high brightness furnishes from wastepaper which varies from batch to batch.

First claim

What is claimed is:

1. A high consistency pulping apparatus comprising:
(a) a pulping tub receiving a wastepaper slurry at a consistency of from 10% to 30%;
(b) a rotor disposed in the pulping tub, coupled to a power drive; and
(c) at least one flow sensor attached to the pulping tub adapted to measure upward slurry flow within the pulping vessel,
wherein the pulping apparatus is operated batchwise and provided in a batch pulping cycle with an initial wastepaper charge having an initial consistency and thereafter during the batch pulping cycle with a wastepaper charge having a consistency of less than the initial consistency and wherein the upward slurry flow is maintained within the range of from 0.05 ft/sec to 0.6 ft/sec during pulping based on the flow sensor measurements of upward slurry flow.

2. The apparatus according to claim 1 , wherein the flow sensor is an ultrasonic Doppler flow sensor.

3. The apparatus according to claim 2 , wherein the flow sensor is a directional Doppler effect ultrasonic flow sensor.

4. The apparatus according to claim 2 , wherein the pulping tub is provided with a plurality of ultrasonic Doppler flow sensors.

5. The apparatus according to claim 1 , wherein the power drive is a variable power drive.

6. The apparatus according to claim 5 , wherein the variable power drive is a variable frequency power drive comprising an AC drive and an AC motor.

7. The apparatus according to claim 1 , wherein the pulping apparatus is operated batchwise and provided in a pulping cycle with an initial wastepaper charge having an initial consistency of above 20% and thereafter during the pulping cycle with a wastepaper charge having a consistency of less than 20%.

8. A high consistency pulping apparatus comprising:
(a) a pulping tub with a bottom and a sidewall containing a wastepaper slurry at a consistency of from 10% to 30% having a height H above the bottom of the tub;
(b) a rotor disposed centrally within the tub coupled to a power drive and being operative to circulate the wastepaper slurry upwardly along the sidewall of the tub and downwardly through the center of the tub; and
(c) at least one flow sensor attached to the pulping tub measuring upward slurry flow along the sidewall of the tub, wherein the flow sensor is disposed at a height of from 10-90% of height, H, above the bottom of the tub and wherein the flow sensor measures upward poloidal velocity of the slurry in the range of from 0.05 ft/sec to 0.5 ft/sec and wherein upward poloidal velocity of the slurry is maintained within the range of from 0.05 ft/sec to 0.5 ft/sec during pulping based on upward poloidal velocity measurements of the flow sensor.

9. The apparatus according to claim 8 , wherein the flow sensor is an ultrasonic Doppler flow sensor.

10. The apparatus according to claim 9 , wherein the flow sensor is a directional Doppler effect ultrasonic flow sensor.

11. The apparatus according to claim 9 , wherein the pulping tub is provided with a plurality of ultrasonic Doppler flow sensors measuring upward slurry flow along the sidewall of the tub.

12. The apparatus according to claim 11 , wherein the pulping tub is provided with a first ultrasonic Doppler flow sensor disposed at a height of from 10-20% of height, H above the bottom of the tub, a second ultrasonic Doppler flow sensor disposed at a height of from 40-60% of height, H above the bottom of the tub, as well as a third ultrasonic Doppler flow sensor disposed at a height of from 70-90% of height, H above the bottom of the tub.

13. The apparatus according to claim 11 , wherein the plurality of ultrasonic Doppler flow sensors measuring upward slurry flow along the sidewall of the tub are circumferentially staggered around a circumference of the tub.

14. The apparatus according to claim 8 , wherein the power drive is a variable power drive.

15. The apparatus according to claim 8 , wherein the wastepaper slurry is at a consistency of from 12% to 25%.

16. The apparatus according to claim 8 , wherein the apparatus delivers an energy input to the wastepaper slurry during pulping within the range of from about 5 kwh/MT to about 40 kwh/MT.

17. The apparatus according to claim 8 , wherein the pulping apparatus is operated batchwise and provided in a batch pulping cycle with an initial wastepaper charge having an initial consistency and thereafter during the batch pulping cycle with a wastepaper charge having a consistency of less than the initial consistency.

18. The apparatus according to claim 17 , wherein the pulping apparatus is operated batchwise and provided in a pulping cycle with an initial wastepaper charge having an initial consistency of above 20% and thereafter during the pulping cycle with a wastepaper charge having a consistency of less than 20%.

Assignees

• Gpcp Ip Holdings Llc

Inventors

• Lee Jeffrey A

Classifications

• D21H11/14

  Secondary fibres (working-up waste paper D21C5/02) · CPC title

• D21C7/00 Primary

  Digesters · CPC title

• D21B1/345

  Pulpers · CPC title

• D21C7/06

  Feeding devices · CPC title

• D21C5/025

  De-inking · CPC title