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JP-7854673-B2 - Industrial furnace

JP7854673B2JP 7854673 B2JP7854673 B2JP 7854673B2JP-7854673-B2

Inventors

  • 竹村 信一郎
  • 井上 武
  • 廣瀬 亮
  • 橋本 望
  • 中村 寿

Assignees

  • ロザイ工業株式会社
  • 国立大学法人北海道大学
  • 国立大学法人東北大学

Dates

Publication Date
20260507
Application Date
20231218
Priority Date
20221222

Claims (5)

  1. A metal or non-ferrous metal industrial furnace is equipped with a regenerative burner that alternately burns at least one pair of burners, stores the waste heat obtained from the combustion of one burner in a heat accumulator of the other burner, and uses that waste heat when burning the other burner, An industrial furnace characterized by having an air nozzle for discharging combustion air into the furnace located in the center of the burner, a fuel nozzle for discharging fossil fuel into the furnace on one side of the air nozzle, and an ammonia nozzle for discharging ammonia into the furnace on the other side, and burning the ammonia in the burner.
  2. On one of the burner sides, the fuel nozzle is provided above the air nozzle, and the ammonia nozzle is provided below it. The industrial furnace according to claim 1, characterized in that the other burner side is provided with the ammonia nozzle above the air nozzle and the fuel nozzle below the air nozzle.
  3. On one of the burner sides, the ammonia nozzle is provided on the left side and the fuel nozzle on the right side when viewed from the air nozzle towards the inside of the furnace. The industrial furnace according to claim 1, characterized in that, on the other burner side, the ammonia nozzle is provided on the left side and the fuel nozzle is provided on the right side when viewed from the air nozzle into the furnace.
  4. The industrial furnace according to claim 2 or 3, characterized in that it is provided with a mechanism for varying the angle of both or one of the fuel nozzle and the ammonia nozzle.
  5. The industrial furnace according to claim 2 or 3, characterized in that a second ammonia nozzle for discharging ammonia into the furnace is provided between the air nozzle and the ammonia nozzle.

Description

This invention relates to industrial furnaces such as heating furnaces, heat treatment furnaces, forging furnaces, melting furnaces, and ladle preheating devices. In recent years, ammonia, which does not produce carbon dioxide when burned, has been attracting attention as a new fuel from the perspective of mitigating global warming. In industrial furnaces, ammonia is rarely used as fuel. While research and development by various research institutions and companies is leading to the practical application of ammonia combustion using conventional burners, it is not used in high-temperature air combustion burners such as regenerative burners. A regenerative burner works by alternately burning a pair of burners, storing the waste heat obtained from the combustion of one burner in a heat regenerator of the other burner, and using that waste heat when burning the other burner (see, for example, Patent Document 1). However, there are no examples of using ammonia as fuel. In particular, when ammonia is mixed with existing fossil fuels or burned alone, it is known that the amount of nitrogen oxides ( NOx ), a combustion product, produced increases by 5 to 10 times compared to the combustion of fossil fuels alone. Therefore, its use in general industrial furnaces is prohibited by environmental regulations. Therefore, equipping industrial furnaces with denitrification equipment in the flue or exhaust gas ducts increases the installation space and significantly raises equipment costs, ultimately leading to higher product prices. Furthermore, in the co-firing of fossil fuels and ammonia, it is necessary to consider the impact on the heated materials that will be processed (the finished product), as well as on the heat-resistant steel and refractories inside the furnace, due to the formation of nitrides and corrosion caused by nitrogen oxides (NOx) contained in the combustion exhaust gas and unburned ammonia. Furthermore, since combustion becomes unstable at low furnace temperatures, it is conceivable to start by burning only existing fossil fuels to raise the furnace temperature, and then switch to co-firing with ammonia once a certain temperature is reached. However, from a decarbonization perspective, it is preferable to achieve ammonia co-firing from as low a temperature as possible. Japanese Patent Publication No. 2015-132408 This is a cross-sectional view showing the main part of an industrial furnace according to an embodiment of the present invention.This is a cross-sectional view taken along line A-A, as shown in Figure 1.This is a schematic diagram showing the fluid supply system to the burner 10 shown in Figure 1.This is a partial cross-sectional view showing the mechanism for varying the angle of the ammonia nozzle 13 shown in Figure 1.This is a schematic diagram showing a fluid supply system to a burner 10 provided in an industrial furnace according to another embodiment of the present invention.This shows an industrial furnace according to yet another embodiment of the present invention, where (a) is a cross-sectional view and (b) is a cross-sectional view taken along line B-B in (a). An industrial furnace 100 according to an embodiment of the present invention will be described with reference to Figures 1 to 3. Here, a metal heating furnace 100 for heating metal will be used as an example of the industrial furnace 100. As shown in Figure 1, the metal heating furnace 100 according to this embodiment has a substantially rectangular cross-section, and a pair of regenerative burners, consisting of burners 10 and 20, are installed on the opposing first side wall 101 and second side wall 102. The regenerative burner alternately burns a pair of burners 10 and 20, storing the waste heat obtained from the combustion of one burner 10 in a heat accumulator 25 provided on the other burner 20, and using that waste heat when the other burner 20 is burned. Furthermore, the waste heat obtained from the combustion of the other burner 20 is stored in a heat accumulator 15 provided on one burner 10, and using that waste heat when the other burner 10 is burned. An air nozzle 11 for discharging combustion air into the furnace is provided in the center of the burner 10 installed on the first side wall 101 of the metal heating furnace 100. On one side of the air nozzle 11, a fuel nozzle 12 for discharging existing fossil fuels into the furnace is provided, and on the other side, an ammonia nozzle 13 for discharging ammonia into the furnace is provided. The air nozzle 11, fuel nozzle 12, and ammonia nozzle 13 are arranged horizontally at arbitrary distances (here, they are assumed to be at equal intervals, but this is not limited to them) on the first side wall 101. That is, the air nozzle 11, fuel nozzle 12, and ammonia nozzle 13 are parallel, and when viewed from the air nozzle 11 towards the inside of the reactor, the ammonia nozzle 13 is located on the left side (arrow S1 side in Figure 1: third side wall 103 side), and the fu