JPH0449467Y2 - - Google Patents

Description

[Detailed explanation of the idea]

(Industrial Application Field) The present invention relates to a non-oxidizing burner suitable for non-oxidizing heating of a steel plate at high speed in a heating furnace. (Prior Art) As a method of heating a steel plate in a non-oxidizing state, a direct flame heating method in which the steel plate is heated by injecting high temperature combustion gas from a burner is well known. This direct heating method is characterized in that the heating rate of the steel sheet is significantly faster than the method of indirectly heating the steel plate using a radiant tube or the like, in which the atmosphere inside the furnace is adjusted with a reducing gas. By the way, as a direct flame heating method for rapidly heating steel plates in a non-oxidizing state, a premixed burner called a radiant cup burner is used, and the air ratio is 0.9.
A method of colliding the gas combusted with the steel plate was proposed in US Pat. No. 3,320,085, and is currently used in annealing furnaces for continuous galvanizing lines. However, the non-oxidizing burner used in this direct-fired non-oxidizing heating method mixes fuel gas and combustion air in advance and then supplies this mixed gas to the burner, which can cause backfires, static electricity, etc. There is a risk of explosion inside the burner or piping. Combustion air cannot be preheated. There are drawbacks such as: Therefore, the present applicant proposed a non-oxidizing burner capable of solving these drawbacks in Utility Application No. 72412/1983. In other words, the non-oxidizing burner previously submitted by the applicant has a double-pipe structure consisting of a combustion air jet pipe and a fuel jet pipe extending through the same, and a swirl vane is installed between these two jet pipes. At the same time, the fuel injection pipe is configured to be movable along the air injection pipe and fixed at a predetermined position, and the fuel injection hole at the front end of the fuel injection pipe is opened at a required angle with respect to the burner central axis. This is what I did. (Problems to be solved by the invention) Although the non-oxidizing burner previously proposed by the present applicant is an excellent product that can solve the drawbacks of conventional burners, subsequent research and experiments by the present inventor et al. have shown the following: It was found that there were problems listed in the following. The combustion air jet pipe is fixedly attached to the furnace with a swirl vane fixed to the inside of its front end, so when the fuel jet pipe inside the combustion air jet pipe is moved in and out, the swirl vane and the fuel jet It is thought that the mixing ratio of the swirling air to the injected fuel changes because the relative positional relationship with the hole changes. Since the fuel injection pipe has an injection hole on the outer periphery of its front end, it is thought that the injection state is likely to change in response to changes in the amount of fuel supplied. The present invention aims to provide a non-oxidizing burner which retains the advantages of the non-oxidizing burner previously proposed by the present applicant and which can solve the inherent problems. (Means for solving the problem) As a countermeasure, the present inventors provided a swirling vane on the fuel injection pipe side so that the relative position of the swirling vane and the injection hole remained constant, and also fixed the combustion air injection pipe. It is made movable relative to the furnace so that it can be moved to follow the fuel injection pipe. A reverse feed pipe is installed inside the front end of the fuel injection pipe,
The injection hole position was changed to maintain the fuel injection pressure as constant as possible to achieve equal pressure injection.
That is, in the present invention, a swirling vane is attached to the fuel injection pipe side in an annular space formed between a combustion air injection pipe and a fuel injection pipe disposed penetrating through the combustion air injection pipe. The non-oxidizing burner is configured with a double pipe so that combustion air can be mixed as a swirling flow with the fuel flow jetted from the front end, and the combustion air jet pipe directs the combustion air to the furnace wall hole and to the furnace wall hole. The fuel injection pipes are configured to be slidable in the axial direction with respect to the combustion air injection pipes and can be fixed at desired positions, and the front ends of the fuel injection pipes are closed, and there are holes inside the front ends. A reversing pipe forming a cylindrical flow path for reversing and reversing the fuel flow is installed inside, and a number of jetting holes opening radially on the outer circumference of this fuel jetting pipe are arranged in front of the swirling vanes to form a burner central axis. This is a non-oxidizing burner that is opened at a predetermined angle to the burner. (Function) Since the non-oxidizing burner according to the present invention has the above-described structure, the fuel collides with the front end of the fuel injection pipe and is reversed and then ejected from the injection hole, so that it is evenly mixed with the combustion air. It becomes good. Moreover, once the fuel collides with the front end of the fuel injection pipe, the front end of the fuel injection pipe is cooled, and burnout of the fuel injection pipe is suppressed. Furthermore, since the relative positions of the combustion air jet pipe and the fuel jet pipe and the relative positions of both jet pipes and the furnace wall hole can be adjusted in a timely manner, optimal heating conditions can be easily obtained, and with long-term use, Even if both ejection pipes are damaged, they can be replaced with new ones. (Embodiments) The present invention will be described below based on embodiments shown in the accompanying drawings. FIG. 1 is a front view showing a longitudinal cross-section of an embodiment of the non-oxidizing burner according to the present invention. It is attached to a furnace wall hole 6 formed in the furnace wall 5 so as to be slidable in the axial direction and fixed at a predetermined position by a set screw 7 screwed into the provided mounting tube 4. Reference numeral 8 denotes a fuel injection pipe which is disposed through the combustion air injection pipe 1 so that it can be slid in the axial direction and fixed at a predetermined position. 9 is formed. In addition,
Reference numeral 10 indicates a set screw for the fuel injection pipe 8. Because of this configuration, even if the combustion air jet pipe 1 and the fuel jet pipe 8 are damaged due to long-term use, the setscrews 7 and 10 can be loosened and the combustion air jet pipe 1 and the fuel jet pipe 8 can be taken out and replaced with new ones. It can be easily replaced. The front end of the fuel injection pipe 8 is closed, and a reverse flow pipe 12 is disposed inside the front end to form a cylindrical flow path for reversely transporting the fuel flow. Therefore, the fuel traveling straight through the fuel injection pipe 8 passes through the reverse feed pipe 12 and collides with the front end of the fuel injection pipe 8, and then is reversely fed back and placed at a position near the front end of the outer periphery of the fuel injection pipe 8. The fuel is uniformly ejected from the fuel injection holes 13 that are radially opened in front of the swirl vanes 11. By the way, in the present invention, an appropriate number of jet holes 13 that open radially are located near the end of the cylindrical flow path and a predetermined distance in front of the swirling blades 11, and furthermore, the burner It is opened at a required angle θ with respect to the central axis, and by making this angle θ, the combustion air that is given a strong swirl by the swirl vane 11 and the fuel injection hole 13 are
The fuel ejected from the fuel tank always mixes well under a constant relative relationship. According to experiments conducted by the present inventors, the above-mentioned θ is 30 to 90 degrees in order to achieve good mixing of fuel and combustion air.
It is desirable that the range be within the range of Further, in the non-oxidizing burner according to the present invention, the fuel flow is once collided with the front end of the fuel jet pipe 8 to cool the front end, and then the fuel jet is passed from the fuel jet hole 13 to the combustion air jet pipe 1.
Since the fuel is ejected inward, damage to the fuel injection pipe 8 is suppressed even when the furnace temperature is extremely high. By the way, the non-oxidation burner according to the present invention can be used not only when the front end of the fuel injection pipe 8 is located in front of the furnace wall hole 6 as shown in FIG. Even if it is located inside the burner nozzle 14, it is suitable because it has non-oxidizing heating ability. In this case, loosen the set screw 7 and
The combustion air jet pipe 1 and the fuel jet pipe 8 may be moved together into the furnace wall hole 6. However, if the furnace temperature is extremely high, even if the front end is cooled by the fuel flow as in the present invention, the front end of the fuel injection pipe 8 will burn out, so it cannot be used when the furnace temperature is relatively low. desirable. 2 shows a mixed fuel jet area reducing member 15 attached to the outlet of the combustion air jet pipe 1, and FIG. 3 shows a mixed fuel jet area reducing member 15 attached to the outlet of the fuel jet pipe 8. By installing this, the miscibility of the fuel and the combustion air is further promoted, and the jetting speed of the mixed fuel is increased, so that the fuel reaches a longer distance, so that the range in which the steel plate is reduced becomes wider. In addition, FIGS. 4 and 5 show that excellent heat-resistant members 16 (for example, heat-resistant metal, ceramics, etc.) are installed at the front end of the fuel injection pipe, and by attaching these members 16, the fuel injection pipe 8 can be improved. Durability is further improved. Next, an experiment was conducted using the non-oxidizing burner of the present invention to perform non-oxidizing heating of a steel plate in the non-oxidizing heating zone of a vertical direct-fired annealing furnace, which is a type of annealing furnace for continuous galvanizing lines. We will discuss the results. The experiment was conducted under the following conditions using the non-oxidizing burner shown in Fig.
This was done by investigating the difference between using the non-oxidizing burner proposed in No. 72412. [Experimental conditions] Steel plate dimensions: 0.8 mm x 1100 mm width Steel plate transfer speed: 145 m/min Fuel: Coke oven gas (COG) Combustion air temperature: 420°C Fuel air ratio supplied to the burner: 0.9 θ in Figure 1 = The results of the 90° experiment are shown in the table below.
Since air preheated to 420°C can be used and the air and fuel are mixed uniformly, the upper limit temperature of the steel plate at which the steel plate can be heated in a non-oxidizing state can be increased by 100°C compared to the comparative example.

[Table] (Effects of the invention) As explained above, since the non-oxidizing burner according to the invention has the above-mentioned configuration, the fuel once collides with the front end of the fuel injection pipe and is reversed and sent back, and then is kept constant from the front end. The combustion air is ejected from the nozzle at the position, and the mixture with the combustion air, which has been given a strong swirl by the action of the swirl vane, is improved. Furthermore, once the fuel collides with the front end of the fuel injection pipe, the front end of the injection pipe is cooled, and burnout of the fuel injection pipe is suppressed. In addition, it becomes possible to change the positions of both jet pipes as appropriate, and to replace the combustion air jet pipe and the fuel jet pipe in the event of fire damage. Furthermore, since preheated air can be used, energy can be saved and safety is also excellent.

[Brief explanation of drawings]

The drawings are cross-sectional front views showing embodiments of the non-oxidation burner according to the present invention, and FIG. 1 shows the first embodiment and the second to second embodiments.
FIG. 5 is an enlarged view of the second to fifth embodiments. 1 is a combustion air jet pipe, 2 is a burner, 7, 10
A locking screw, 8 a fuel injection pipe, 11 a swirl vane,
12 is a reverse feed pipe, and 13 is a fuel injection hole.

Claims (1)

[Scope of utility model registration request] Fuel jetted from the front end of the fuel jet pipe by interposing swirl vanes on the side of the fuel jet pipe in an annular space formed between a combustion air jet pipe and a fuel jet pipe extending through the fuel jet pipe. The non-oxidizing burner has a double pipe structure so that fuel air can be mixed with the flow as a swirling flow, and the combustion air jet pipe is connected to the furnace wall hole, and the fuel jet pipe is connected to the furnace wall hole. The combustion air jet pipe is configured to be slidable in the axial direction and fixed at a desired position with respect to the combustion air jet pipe, and the front end of the fuel jet pipe is closed, and a fuel flow is allowed inside the front end. A reverse feed pipe forming a cylindrical flow path for reversing and reverse feeding is installed inside, and a number of injection holes opening radially on the outer periphery of the fuel injection pipe are arranged in front of the swirling vanes at a predetermined angle with respect to the burner central axis. A non-oxidizing burner characterized in that it is opened with.