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

Patent metadata

Field	Value
Publication number	US-2021010200-A1
Application number	US-201816606911-A
Country	US
Kind code	A1
Filing date	May 1, 2018
Priority date	May 3, 2017
Publication date	Jan 14, 2021
Grant date	—

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

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 receiving a flow of smelt and having a vent stack in fluid communication with the smelt dissolving tank, comprising:
a processing unit; and 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 control system for a smelt dissolving tank receiving a flow of smelt and having a vent stack in fluid communication with the smelt dissolving tank, comprising:
a sensor configured to measure a temperature of a flow of 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 the 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

• D21C11/0064

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

• D21C7/12 Primary

  Devices for regulating or controlling · CPC title

• D21C11/00

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