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KR-20260065900-A - Method for estimating unburned ammonia concentration, method of operating a heating furnace, method of operating a burner equipment, and control device for a heating furnace

KR20260065900AKR 20260065900 AKR20260065900 AKR 20260065900AKR-20260065900-A

Abstract

The present invention provides a method for estimating unburned ammonia that can measure online the concentration of ammonia contained in the exhaust gas of a furnace (1) that uses ammonia as a fuel gas, which can suppress the emission of carbon dioxide. In addition, the present invention provides a method for operating a furnace, a method for operating a burner equipment, and a control device for a furnace that can suppress the emission of unburned ammonia as exhaust gas of the furnace (1) outside the furnace. A method for estimating the concentration of unburned ammonia contained in exhaust gas discharged from a furnace that performs burner heating using a fuel gas containing ammonia and carbon-containing fuel, the method comprising: a specific step for specifying the correlation between the concentration of carbon monoxide contained in the exhaust gas of the furnace and the concentration of unburned ammonia; a measurement step for measuring the concentration of carbon monoxide contained in the exhaust gas of the furnace during the operation of the furnace; and an estimation step for estimating the concentration of unburned ammonia contained in the exhaust gas of the furnace based on the carbon monoxide concentration measured in the measurement step and the correlation between the carbon monoxide concentration and the concentration of unburned ammonia specified in the specific step.

Inventors

  • 노지마 유스케

Assignees

  • 제이에프이 스틸 가부시키가이샤

Dates

Publication Date
20260511
Application Date
20240722
Priority Date
20231219

Claims (10)

  1. A method for estimating the concentration of unburned ammonia contained in exhaust gas discharged from a furnace that performs burner heating using fuel gas containing ammonia and carbon-containing fuel, wherein A specific step for determining the correlation between the concentration of carbon monoxide and the concentration of unburned ammonia contained in the exhaust gas of the above-mentioned furnace, and A measurement step for measuring the concentration of carbon monoxide contained in the exhaust gas of the furnace during the operation of the furnace, and An estimation step for estimating the concentration of unburned ammonia contained in the exhaust gas of the furnace based on the carbon monoxide concentration measured in the above measurement step and the correlation between the carbon monoxide concentration and the unburned ammonia concentration specified in the above specific step. A method for estimating unburned ammonia concentration, including
  2. In Article 1, The above specific step is a method for estimating the concentration of unburned ammonia, wherein for each classification in which the operating conditions of the furnace are classified into multiple types, the correlation between the concentration of carbon monoxide and the concentration of unburned ammonia contained in the exhaust gas of the furnace is specified.
  3. In Article 1 or Article 2, The above heating furnace is a conveying type heating furnace that heats a material to be heated while conveying it from the charging section to the discharging section. A method for estimating the concentration of unburned ammonia, wherein the above measurement step measures the concentration of carbon monoxide contained in the exhaust gas of the furnace at at least one point among the flue discharging exhaust gas from the furnace, the charging section, and the discharge section.
  4. A method for estimating the concentration of unburned ammonia contained in exhaust gas emitted from a burner facility that performs burner heating using a fuel gas containing ammonia and carbon-containing fuel, wherein A specific step for determining the correlation between the carbon monoxide concentration and the unburned ammonia concentration contained in the exhaust gas of the burner equipment, and A measurement step for measuring the concentration of carbon monoxide contained in the exhaust gas of the burner equipment when performing burner heating by the burner equipment, and An estimation step for estimating the concentration of unburned ammonia contained in the exhaust gas of the burner equipment based on the carbon monoxide concentration measured in the above measurement step and the correlation between the carbon monoxide concentration and the unburned ammonia concentration specified in the above specific step. A method for estimating unburned ammonia concentration, including
  5. In Article 4, The above specific step is a method for estimating the concentration of unburned ammonia, wherein for each classification in which the operating conditions of the burner equipment are classified into multiple types, the correlation between the concentration of carbon monoxide and the concentration of unburned ammonia contained in the exhaust gas of the burner equipment is specified.
  6. A method for operating a furnace, comprising an operation step of operating the furnace's operating conditions such that when the estimated value of the unburned ammonia concentration estimated by the method for estimating the unburned ammonia concentration described in claim 3 is greater than or equal to a predetermined value, the unburned ammonia concentration contained in the exhaust gas discharged from the furnace is reduced.
  7. In Article 6, A method for operating a furnace, wherein the operating conditions of the furnace that are changed in the above operation step include at least one of the flow rate of combustion air used for heating the burner, the flow rate of the fuel gas, the air ratio of the fuel gas to the theoretical amount of air, and the mixing ratio of the ammonia and the carbon-containing fuel.
  8. A method for operating a burner facility, comprising an operation step of operating the operating conditions of the burner facility such that when the estimated value of the unburned ammonia concentration estimated by the method for estimating the unburned ammonia concentration described in claim 4 is greater than or equal to a predetermined value, the unburned ammonia concentration contained in the exhaust gas discharged from the burner facility is reduced.
  9. In Article 8, A method of operating a burner facility, wherein the operating conditions of the burner facility that are changed in the above operation step include at least one of the flow rate of combustion air used for heating the burner, the flow rate of the fuel gas, the air ratio of the fuel gas to the theoretical amount of air, and the mixing ratio of the ammonia and the carbon-containing fuel.
  10. A control device for a heating furnace that performs burner heating using a fuel gas containing ammonia and carbon-containing fuel, A memory unit that stores the correlation between the concentration of carbon monoxide and the concentration of unburned ammonia contained in the exhaust gas of the above-mentioned heating furnace, and A acquiring unit for acquiring the concentration of carbon monoxide contained in the exhaust gas of the furnace measured during the operation of the furnace, and An estimation unit that estimates the concentration of unburned ammonia contained in the exhaust gas of the heating furnace based on the carbon monoxide concentration acquired by the above-mentioned acquisition unit and the correlation between the carbon monoxide concentration and the unburned ammonia concentration stored in the above-mentioned memory unit, and A control device for a heating furnace, comprising a control amount calculation unit for calculating a control amount of the operating conditions of the heating furnace to make the estimated value of the unburned ammonia concentration estimated by the above estimation unit become smaller than the above predetermined value when the estimated value is greater than or equal to the above predetermined value.

Description

Method for estimating unburned ammonia concentration, method of operating a heating furnace, method of operating a burner equipment, and control device for a heating furnace The present invention relates to a method for estimating the concentration of unburned ammonia, a method for operating a heating furnace, a method for operating a burner facility, and a control device for a heating furnace. In integrated steel mills, byproduct gases—such as blast furnace gas discharged from the furnace top of the blast furnace used to reduce iron ore to produce molten iron, converter gas generated from converters, and coke oven gas generated from coke ovens—are effectively utilized as fuel gases. However, with the recent increase in demands for reducing carbon dioxide emissions, combustion technologies are required to decrease the usage of these byproduct gases. In the heating furnaces that heat slabs prior to rolling in hot rolling lines and plate rolling lines of integrated steel mills, it is also required to reduce the use of byproduct gases and thereby decrease carbon dioxide emissions. Therefore, the technology of using ammonia as a fuel gas for heating furnaces is attracting attention. Since the combustion of ammonia, which does not contain carbon elements, produces mainly water and nitrogen, it has a significant effect on reducing carbon dioxide emissions, and thus the development of technology to use ammonia as a fuel gas for heating furnaces is desired. However, since ammonia is toxic, if unburned ammonia (also called "unburned ammonia") is released outside the furnace, it deteriorates the environment outside the furnace. For this reason, when using ammonia as a fuel gas for a furnace, it is necessary to measure the concentration of unburned ammonia contained in the furnace exhaust gas to prevent unburned ammonia from being released outside the furnace. In this regard, Patent Document 1 discloses a method for analyzing ammonia gas in exhaust gas discharged from the outlet of a denitrification device that treats boiler exhaust gas. Specifically, when analyzing ammonia gas coexisting with sulfur dioxide by the indophenol method, the analytical precision is improved by distilling the absorption solution to remove SO₃²⁻ions in the solution. The indophenol method, also known as the indophenol blue spectrophotometric method, is a method of calculating the concentration of ammonia in gas by absorbing ammonia in the gas into a boric acid solution, adding a sodium phenolpentacyanonitrosilferri(III)ate solution and a sodium hypochlorite solution to produce indophenol blue, and measuring the absorbance (640 nm). In addition to the indophenol method, ion chromatography is also known as a method for analyzing ammonia in exhaust gas. Ion chromatography is a method in which ammonia in the gas is absorbed into a boric acid solution, a sample solution for analysis is injected into an ion chromatograph, a chromatogram of ammonium ions is obtained, and the concentration of ammonia in the gas is calculated from the ammonium ion concentration. In addition, Patent Document 2 discloses a method for analyzing ammoniacal nitrogen, nitrate/nitrite nitrogen, and total nitrogen. Specifically, a method is described in which ammonia gas is oxidized into NO gas by an oxidation catalyst formed in the combustion section of a heated reaction tube, and the NO gas is sent to a chemiluminescent NO detector to analyze ammoniacal nitrogen. In addition, Non-patent Literature 1 discloses a dry gas measurement method for measuring ammonia concentration using an infrared analyzer. Specifically, a method is disclosed in which a cooler is installed in a pipe that returns the gas to be measured to the infrared analyzer, and thereby the dehumidified gas is provided to the infrared analyzer. FIG. 1 is a cross-sectional view schematically showing a furnace to which an embodiment of the method for estimating unburned ammonia concentration, the method for operating a furnace, the method for operating a burner facility, and the control device for a furnace related to the present invention is applied. FIG. 2 is a cross-sectional view schematically showing a furnace to which an embodiment of the method for estimating unburned ammonia concentration, the method for operating a furnace, the method for operating a burner facility, and the control device for a furnace related to the present invention is applied. FIGS. 3(a) and FIGS. 3(b) are a side view and a front view showing details of a burner equipment using ammonia as a fuel gas. FIGS. 4(a) and FIGS. 4(b) are a side view and a front view showing details of a burner system that does not use ammonia as a fuel gas. Figure 5 is a graph showing the correlation between the concentration of carbon monoxide and the concentration of unburned ammonia in the exhaust gas from a burner facility when the combustion rate of the carbon-containing fuel included in the fuel gas is faster than the combustion rate of ammonia. Figure