Method for controlling carryover in a chemical recovery boiler and a chemical recovery boiler

Patent metadata

Field	Value
Publication number	US-11746470-B2
Application number	US-202017015635-A
Country	US
Kind code	B2
Filing date	Sep 9, 2020
Priority date	Sep 9, 2019
Publication date	Sep 5, 2023
Grant date	Sep 5, 2023

Abstract

A method for controlling carryover in a chemical recovery boiler. The method comprises feeding black or brown liquor to a furnace of the chemical recovery boiler through an injection gun to burn the black or brown liquor. The chemical recovery boiler comprises a bullnose, which narrows the furnace, and a first superheater, of which at least a part is arranged at a higher vertical level than the bullnose. The method comprises measuring information indicative of a spatial temperature distribution on a cross section of the furnace, wherein the cross section is above the injection gun and below the first superheater; determining primary information indicative of carryover using the information indicative of the spatial temperature distribution on the cross section of the furnace; and controlling a temperature of the black or brown liquor that is fed to the furnace using the primary information. In addition, a system for performing the method.

First claim

The invention claimed is:

1. A method for controlling carryover in a chemical recovery boiler, the method comprising the steps of:
feeding black or brown liquor to a furnace of the chemical recovery boiler through an injection gun to burn the black or brown liquor, wherein the chemical recovery boiler comprises a bullnose, which narrows the furnace, and a first superheater, of which at least a part is arranged at a higher vertical level than the bullnose,
measuring information indicative of a spatial temperature distribution on a cross section of the furnace, wherein the cross section is above the injection gun and below the first superheater,
determining, by using the information indicative of the spatial temperature distribution on the cross section of the furnace, primary information that is indicative of at least one of: presence of carryover particles within the cross section of the furnace, an amount of the carryover particles within the cross section of the furnace, and a change of the amount of the carryover particles within the cross section of the furnace, and
controlling a temperature of the black or brown liquor that is fed to the furnace using the primary information.

2. The method of claim 1 , further comprising the steps of:
determining the spatial temperature distribution on the cross section of the furnace using the information indicative of the spatial temperature distribution on the cross section of the furnace,
determining a statistical measure of the spatial temperature distribution, and
determining that the statistical measure exceeds a threshold to determine the primary information.

3. The method of claim 1 , further comprising the steps of:
determining the spatial temperature distribution on the cross section of the furnace using the information indicative of the spatial temperature distribution on the cross section of the furnace,
determining a statistical measure indicative of a variation of the spatial temperature distribution, and
determining that the statistical measure indicative of the variation exceeds a first threshold to determine the primary information.

4. The method of claim 3 , wherein:
black or brown liquor is fed through multiple injection guns to the furnace, the method comprises:
feeding combustion air into the furnace through multiple air inlets; and
affecting combustion of the black or brown liquor in such a way that a variation of the spatial temperature distribution decreases.

5. The method of claim 3 , further comprising the steps of:
determining a statistical measure indicative of a magnitude of the spatial temperature distribution, and determining that the statistical measure indicative of the magnitude exceeds a second threshold to determining the primary information.

6. The method of claim 3 , further comprising decreasing the temperature of the black or brown liquor that is fed to the furnace.

7. The method of claim 1 , further comprising the steps of:
determining the spatial temperature distribution on the cross section of the furnace using the information indicative of the spatial temperature distribution on the cross section of the furnace, determining a statistical measure indicative of a magnitude of the spatial temperature distribution, and determining that the statistical measure indicative of the magnitude exceeds a threshold to determining the primary information.

8. The method of claim 7 , further comprising decreasing the temperature of the black or brown liquor that is fed to the furnace.

9. The method of claim 1 , wherein the information indicative of the spatial temperature distribution on the cross section of the furnace is measured by using at least one of the following: acoustic pyrometry, temperature sensors arranged within the furnace, spectroscopy, or optical pyrometrybly.

10. The method of claim 1 , further comprising:
controlling, by using the primary information, a flow of combustion air into the furnace;
wherein the flow of combustion air into the furnace is controlled by controlling at least such a valve that is configured to control a total amount of combustion air to a vertical level of the chemical recovery boiler.

11. The method of claim 1 , wherein:
a char bed is formed in the furnace such that at least a part of the char bed is arranged at a lower vertical level than the injection gun, and
the method further comprises:
determining information indicative of a height and/or shape of the char bed, and
controlling the temperature of the black or brown liquor that is fed to the furnace using the information indicative of height and/or shape of the char bed.

12. The method of claim 11 , further comprising:
determining information indicative of a temperature of the char bed, and
controlling the temperature of the black or brown liquor that is fed to the furnace using the information indicative of the temperature of the char bed.

13. The method of claim 1 , wherein:
a char bed is formed in the furnace such that at least a part of the char bed is arranged at a lower vertical level than the injection gun, and
the method further comprises:
determining information indicative of a temperature of the char bed, and
controlling the temperature of the black or brown liquor that is fed to the furnace using the information indicative of the temperature of the char bed.

14. A chemical recovery boiler, comprising:
a furnace,
a bullnose, which narrows the furnace,
a first superheater, of which at least a part is arranged at a higher vertical level than the bullnose,
an injection gun for feeding black or brown liquor into the furnace,
a thermometer configured to measure values indicative of a spatial temperature distribution on a cross section of the furnace, wherein the cross section is above the injection gun and below the first superheater,
a temperature controller configured to control a temperature of the black or brown liquor that is fed by the injection gun, and
a processor configured to determine, using the values indicative of the spatial temperature distribution on the cross section of the furnace, primary information indicative of at least one of: presence of carryover particles within the cross section of the furnace, an amount of the carryover particles within the cross section of the furnace, and a change of the amount of the carryover particles within the cross section of the furnace.

15. The chemical recovery boiler of claim 14 , wherein the processor is configured to at least one of:
control the temperature controller using the primary information,
provide the primary information to an operator, or
generate a signal using the primary information and provide the signal to an operator.

16. The chemical recovery boiler of claim 14 , further comprising:
multiple injection guns for feeding black or brown liquor into the furnace, and
multiple air inlets for feeding combustion air into the furnace,
wherein the processor is further configured to at least one of:
control an angle of a first injection gun independent of an angle of a second injection gun,
control a flow of the black or brown liquor through a first injection gun independent of a flow of the black or brown liquor through a second injection gun, or
control a flow of combustion air through a first air inlet independent of a flow of combustion air through a second air inlet.

17. The chemical recovery boiler of claim 14 , wherein the thermometer comprises at least one of the following:
an acoustic pyrometer having at least two sound sources and multiple sound detectors,
temper

Assignees

• Valmet Automation Oy

Inventors

• Mansikkasalo Jarmo
• Koskinen Jukka

Classifications

• D21C11/12 Primary

  Combustion of pulp liquors · CPC title

• F23G7/04

  of waste liquors, e.g. sulfite liquors · CPC title

• F22B1/20

  using heat evolved in a solution absorbing steam; Soda steam boilers · CPC title

• F22B35/00

  Control systems for steam boilers (for regulating feed-water supply F22D5/00; for controlling superheat temperature F22G5/00) · CPC title

• F23G5/50

  Control or safety arrangements · CPC title