Vent stack temperature as a feedforward variable for smelt dissolving tank TTA control

Patent metadata

Field	Value
Publication number	US-11441265-B2
Application number	US-201816606911-A
Country	US
Kind code	B2
Filing date	May 1, 2018
Priority date	May 3, 2017
Publication date	Sep 13, 2022
Grant date	Sep 13, 2022

Abstract

Methods and systems for controlling operation of a smelt dissolving tank receiving a flow of smelt and having a vent stack in fluid communication are provided. A dissolving liquid is injected into the smelt dissolving tank at a predetermined injection rate. A temperature of a flow of vapour in the vent stack is measured with a sensor. The injection rate of the dissolving liquid is controlled based on the temperature of the flow of vapour.

First claim

The invention claimed is:

1. A method for controlling operation of a smelt dissolving tank receiving a flow of smelt and having a vent stack in fluid communication with the smelt dissolving tank, comprising:
injecting, at a predetermined injection rate, a dissolving liquid into the smelt dissolving tank;
measuring a temperature of a flow of vapour in the vent stack with a sensor; and
controlling the injection rate of the dissolving liquid based on the temperature of the flow of vapour.

2. The method of claim 1 , further comprising:
measuring at least one parameter of an output product of the smelt dissolving tank; and
further adjusting the injection rate of the dissolving liquid based on the at least one parameter.

3. The method of claim 2 , wherein the output product is green liquor.

4. The method of claim 3 , wherein the at least one parameter comprises a density of the green liquor.

5. The method of claim 3 , wherein the at least one parameter is a concentration of total titratable alkali in the green liquor.

6. The method of claim 1 , wherein adjusting the injection rate comprises setting the injection rate between a predetermined minimum injection rate and a predetermined maximum injection rate.

7. The method of claim 6 , wherein at least one of the minimum injection rate and the maximum injection rate is based on a safety requirement.

8. The method of claim 1 , wherein the dissolving liquid is recycled water from a milling process.

9. The method of claim 1 , wherein measuring the temperature with the sensor comprises measuring the temperature with the sensor located within the vent stack.

10. The method of claim 1 , wherein measuring the temperature with the sensor comprises measuring the temperature with the sensor located at an output of the vent stack.

11. A system for controlling operation of a smelt dissolving tank, comprising:
the smelt dissolving tank receiving a flow of smelt and having a vent stack in fluid communication with the smelt dissolving tank;
a processing unit; and
a sensor coupled to the processing unit, the sensor positioned at the vent stack of the smelt dissolving tank;
a non-transitory computer-readable memory having stored thereon program instructions executable by the processing unit for:
injecting, at a predetermined injection rate, a dissolving liquid into the smelt dissolving tank;
measuring a temperature of a flow of vapour in the vent stack with a sensor; and
controlling the injection rate of the dissolving liquid based on the temperature of the flow of vapour.

12. The system of claim 11 , wherein the program instructions are further executable for:
measuring at least one parameter of an output product of the smelt dissolving tank; and
further adjusting the injection rate of the dissolving liquid based on the at least one parameter.

13. The system of claim 12 , wherein the output product is green liquor.

14. The system of claim 13 , wherein the at least one parameter comprises a density of the green liquor.

15. The system of claim 13 , wherein the at least one parameter is a concentration of total titratable alkali in the green liquor.

16. The system of claim 11 , wherein adjusting the injection rate comprises setting the injection rate between a predetermined minimum injection rate and a predetermined maximum injection rate.

17. The system of claim 11 , wherein the dissolving liquid is recycled water from a milling process.

18. The system of claim 11 , wherein the sensor is located within the vent stack.

19. The system of claim 11 , wherein the sensor is located at an output of the vent stack.

20. A system comprising:
a smelt dissolving tank adapted to receive a flow of smelt;
a vent stack in fluid communication with the smelt dissolving tank;
a sensor positioned at the vent stack, configured to measure a temperature of a flow vapour in the vent stack; and
an injection rate controller configured to:
receive a reading indicative of the temperature from the sensor; and

control an injection rate of a dissolving liquid into the smelt dissolving tank based on the reading.

Assignees

• Fpinnovations

Inventors

• Allison Bruce James
• Ren Wei
• Dubord Brennan
• Johnson Jason

Classifications

• D21C11/122 Primary

  Treatment, e.g. dissolution, of the smelt · CPC title

• D21C11/00

  Regeneration of pulp liquors {or effluent waste waters} · CPC title

• D21C7/12 Primary

  Devices for regulating or controlling · CPC title

• D21C11/0064

  Aspects concerning the production and the treatment of green and white liquors, e.g. causticizing green liquor · CPC title