# US 11,441,265 B2 · Vent stack temperature as a feedforward variable for smelt dissolving tank TTA control > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,441,265 B2 - Document ID: US11441265B2 - Status: Granted - Kind: B2 - Application number: 16/606,911 - Filed: 2018-05-01 - Published: 2021-01-14 - Granted: 2022-09-13 - Earliest claimed: 2017-05-03 - Assignees: FPInnovations - Applicants: FPInnovations - Inventors: Bruce James Allison; Wei Ren; Brennan Dubord; Jason Johnson - Web page: https://patentgrep.com/patent/US11441265B2 ## CPC - D21C 11/122: {Treatment, e.g. dissolution, of the smelt} - D21C 7/12: Devices for regulating or controlling - D21C 11/00: Regeneration of pulp liquors {or effluent waste waters} - D21C 11/0064: {Aspects concerning the production and the treatment of green and white liquors, e.g. causticizing green liquor} - D21C: PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR ## 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. ## Claims ### 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. ### Claim 2 (depends on 1) 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. ### Claim 3 (depends on 2) The method of claim 2, wherein the output product is green liquor. ### Claim 4 (depends on 3) The method of claim 3, wherein the at least one parameter comprises a density of the green liquor. ### Claim 5 (depends on 3) The method of claim 3, wherein the at least one parameter is a concentration of total titratable alkali in the green liquor. ### Claim 6 (depends on 1) 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. ### Claim 7 (depends on 6) 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. ### Claim 8 (depends on 1) The method of claim 1, wherein the dissolving liquid is recycled water from a milling process. ### Claim 9 (depends on 1) The method of claim 1, wherein measuring the temperature with the sensor comprises measuring the temperature with the sensor located within the vent stack. ### Claim 10 (depends on 1) 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. ### Claim 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. ### Claim 12 (depends on 11) 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. ### Claim 13 (depends on 12) The system of claim 12, wherein the output product is green liquor. ### Claim 14 (depends on 13) The system of claim 13, wherein the at least one parameter comprises a density of the green liquor. ### Claim 15 (depends on 13) The system of claim 13, wherein the at least one parameter is a concentration of total titratable alkali in the green liquor. ### Claim 16 (depends on 11) 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. ### Claim 17 (depends on 11) The system of claim 11, wherein the dissolving liquid is recycled water from a milling process. ### Claim 18 (depends on 11) The system of claim 11, wherein the sensor is located within the vent stack. ### Claim 19 (depends on 11) The system of claim 11, wherein the sensor is located at an output of the vent stack. ### Claim 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.