CN-122003572-A - Method for estimating unburned ammonia concentration, method for operating heating furnace, method for operating burner device, and control device for heating furnace

Abstract

The application provides a method for estimating unburned ammonia, which can measure the ammonia concentration in the exhaust gas of a heating furnace (1) using ammonia capable of inhibiting the discharge of carbon dioxide as fuel gas on line by a simple method. Further, provided are a method for operating a heating furnace, a method for operating a burner device, and a control device for the heating furnace, which are capable of suppressing the discharge of unburned ammonia, which is the exhaust gas of the heating furnace (1), to the outside of the furnace. A method for estimating the concentration of unburned ammonia contained in an exhaust gas from a heating furnace which is heated by a burner using a fuel gas containing ammonia and a carbonaceous fuel, wherein the method for estimating the concentration of unburned ammonia comprises a determination step of determining a correlation between the concentration of carbon monoxide contained in the exhaust gas of the heating furnace and the concentration of unburned ammonia, a measurement step of measuring the concentration of carbon monoxide contained in the exhaust gas of the heating furnace during operation of the heating furnace, and an estimation step of estimating the concentration of unburned ammonia contained in the exhaust gas of the heating furnace based on the concentration of carbon monoxide measured in the measurement step and the correlation between the concentration of carbon monoxide and the concentration of unburned ammonia determined in the determination step.

Inventors

• Noban Yusuke

Assignees

• 杰富意钢铁株式会社

Dates

Publication Date

20260508

Application Date

20240722

Priority Date

20231219

Claims (10)

1. 1. A method of estimating the concentration of unburned ammonia, estimating the concentration of unburned ammonia contained in exhaust gas discharged from a heating furnace that performs burner heating using fuel gas containing ammonia and carbon-containing fuel, wherein, The method for estimating the unburned ammonia concentration comprises the following steps: A determining step of determining a correlation between a carbon monoxide concentration and an unburned ammonia concentration contained in an exhaust gas of the heating furnace; a measurement step of measuring a carbon monoxide concentration contained in an exhaust gas of the heating furnace during operation of the heating furnace, and An estimation step of estimating an unburned ammonia concentration contained in the exhaust gas of the heating furnace based on the carbon monoxide concentration measured in the measurement step and a correlation between the carbon monoxide concentration and the unburned ammonia concentration determined in the determination step.
2. 2. The method for estimating an unburned ammonia concentration according to claim 1, wherein, In the determining step, a correlation between a carbon monoxide concentration and an unburned ammonia concentration contained in the exhaust gas of the heating furnace is determined for each of a plurality of categories of operating conditions of the heating furnace.
3. 3. The method for estimating an unburned ammonia concentration according to claim 1 or 2, wherein, The heating furnace is a conveying type heating furnace which heats a material to be heated while conveying the material from a loading part to a carrying-out part, In the measuring step, a carbon monoxide concentration contained in the exhaust gas of the heating furnace is measured at least one of a flue through which the exhaust gas is discharged from the heating furnace, the loading unit, and the unloading unit.
4. 4. A method of estimating the concentration of unburned ammonia, estimating the concentration of unburned ammonia contained in exhaust gas discharged from a burner apparatus that performs burner heating using fuel gas containing ammonia and a carbon-containing fuel, wherein, The method for estimating the unburned ammonia concentration comprises the following steps: A determining step of determining a correlation between a carbon monoxide concentration and an unburned ammonia concentration contained in an exhaust gas of the burner apparatus; A measurement step of measuring a concentration of carbon monoxide contained in an exhaust gas of the burner apparatus when burner heating is performed by the burner apparatus, and An estimation step of estimating an unburned ammonia concentration contained in the exhaust gas of the burner device based on the carbon monoxide concentration measured in the measurement step and a correlation between the carbon monoxide concentration and the unburned ammonia concentration determined in the determination step.
5. 5. The method for estimating an unburned ammonia concentration according to claim 4, wherein, In the determining step, a correlation between a carbon monoxide concentration and an unburned ammonia concentration contained in the exhaust gas of the burner apparatus is determined for each of a plurality of categories of operating conditions of the burner apparatus.
6. 6. A method of operating a heating furnace, comprising an operation step of operating an operating condition of the heating furnace such that an unburned ammonia concentration contained in an exhaust gas discharged from the heating furnace becomes smaller when an estimated value of the unburned ammonia concentration estimated by the method of estimating an unburned ammonia concentration according to claim 3 is equal to or higher than a predetermined value.
7. 7. The method of operating a heating furnace according to claim 6, wherein, The operation conditions of the heating furnace changed in the operation step include at least one of a flow rate of combustion air for the burner heating, a flow rate of the fuel gas, an air ratio of the fuel gas with respect to a theoretical air amount, and a mixing ratio of the ammonia and the carbonaceous fuel.
8. 8. A method of operating a burner apparatus, comprising an operation step of operating an operating condition of the burner apparatus so that an unburned ammonia concentration contained in an exhaust gas discharged from the burner apparatus becomes smaller when an estimated value of the unburned ammonia concentration estimated by the method of estimating an unburned ammonia concentration according to claim 4 is equal to or higher than a predetermined value.
9. 9. The method of operating a burner apparatus of claim 8 wherein, The operating conditions of the burner apparatus changed in the operating step include at least one of a flow rate of combustion air for the burner heating, a flow rate of the fuel gas, an air ratio of the fuel gas with respect to a theoretical air amount, and a mixing ratio of the ammonia and the carbonaceous fuel.
10. 10. A control device of a heating furnace which uses a fuel gas containing ammonia and a carbon-containing fuel to perform burner heating, wherein, The control device of the heating furnace comprises: a storage unit that stores a correlation between a concentration of carbon monoxide contained in exhaust gas of the heating furnace and a concentration of unburned ammonia; An acquisition unit that acquires a carbon monoxide concentration contained in an exhaust gas of the heating furnace measured during operation of the heating furnace; an estimating unit that estimates an unburned ammonia concentration contained in the exhaust gas of the heating furnace based on the correlation between the carbon monoxide concentration acquired by the acquiring unit and the carbon monoxide concentration and the unburned ammonia concentration stored in the storage unit, and An operation amount calculation unit that calculates an operation amount for operating conditions of the heating furnace such that the estimated value is smaller than a predetermined value when the estimated value of the unburned ammonia concentration estimated by the estimation unit is equal to or greater than the predetermined value.

Description

Method for estimating unburned ammonia concentration, method for operating heating furnace, method for operating burner device, and control device for heating furnace Technical Field The present invention relates to a method for estimating an unburned ammonia concentration, a method for operating a heating furnace, a method for operating a burner device, and a control device for the heating furnace. Background In a combined iron and steel mill, by-product gases such as blast furnace gas discharged from the top of a blast furnace for producing molten iron by reducing iron ore, converter gas produced in a converter, and coke oven gas produced in a coke oven are effectively used as fuel gas. However, in recent years, there has been an increasing demand for reduction of carbon dioxide emissions, and there has been a demand for a combustion technology for reducing the amount of these by-product gases. In a hot rolling line, a thick plate rolling line, and the like in a steel and iron mill, even in a heating furnace for heating a slab before rolling, it is required to reduce the amount of by-product gas used and reduce the amount of carbon dioxide emissions. Therefore, attention is paid to a technique of using ammonia as a fuel gas for a heating furnace. Since only water and nitrogen are mainly produced when ammonia containing no carbon element is burned, the effect of reducing the carbon dioxide emissions is great, and it is desired to develop a technique for using ammonia as a fuel gas for a heating furnace. However, since ammonia is toxic, if unburned ammonia (also referred to as "unburned ammonia") is discharged to the outside of the heating furnace, the external environment of the heating furnace is deteriorated. Therefore, in the case of using ammonia as the fuel gas of the heating furnace, it is necessary to measure the concentration of unburned ammonia contained in the exhaust gas of the heating furnace in order to suppress the emission of unburned ammonia to the outside of the heating furnace. In view of this, patent document 1 discloses a method of analyzing ammonia gas in exhaust gas discharged from an outlet of a denitration device for treating boiler exhaust gas. Specifically, when ammonia gas in which sulfur dioxide is present is analyzed by the indophenol method, SO 32- ions in the liquid are removed by distilling the absorption liquid, thereby improving the analysis accuracy. The indophenol method is also called as an indophenol blue absorbance method, and is a method in which boric acid solution is allowed to absorb ammonia in a gas, then sodium phenolpentacyano nitrosoiron (III) carboxylate solution and sodium hypochlorite solution are added to generate indophenol blue, and the absorbance (640 nm) is measured to calculate the ammonia concentration in the gas. As a method for analyzing ammonia in exhaust gas, ion chromatography is known in addition to the indophenol method. Ion chromatography is a method in which a boric acid solution is allowed to absorb ammonia in a gas, and then a sample solution for analysis is injected into an ion chromatograph to obtain a chromatogram of ammonium ions, and the concentration of ammonia in the gas is calculated from the concentration of ammonium ions. Patent document 2 discloses a method for analyzing ammonia nitrogen and nitric acid/nitrous acid nitrogen, and total nitrogen. Specifically, a method is described in which ammonia gas is oxidized into NO gas by an oxidation catalyst provided in a combustion section of a heated reaction tube, and the NO gas is sent to a chemiluminescent NO detector to analyze ammonia nitrogen. Further, non-patent document 1 discloses a dry gas measurement method for measuring an ammonia concentration using an infrared analyzer. Specifically, a method is disclosed in which a cooler is provided in a pipe for conveying a gas to be measured to an infrared analyzer, and the dehumidified gas is supplied to the infrared analyzer. Prior art literature Patent literature Patent document 1 Japanese patent laid-open No. 61-17955 Patent document 2 Japanese patent application laid-open No. 2001-21546 Non-patent literature Non-patent document 1: gong Benmin, implementation status of "Infrared gas Analyzer", journal of Industrial chemistry, society of chemical society, japan, proc. Nature, 1963, 11 th month, volume 66, 11 th, p.1561-1563) Disclosure of Invention Problems to be solved by the invention However, if the above-described conventional technique is applied to measurement of the concentration of unburned ammonia contained in the exhaust gas of a heating furnace, the following problems occur. First, in order to measure the ammonia concentration by the method disclosed in patent document 1, steps such as absorption of ammonia gas into an absorption liquid, reaction with a reagent, and analysis are required. That is, it is necessary to measure the ammonia concentration by batch processing, and it takes a certain time (for example, 10 minute