JP3720905B2 - Industrial furnace combustion equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a combustion apparatus that recovers exhaust gas sensible heat by high-temperature preheating of combustion air and is effective in energy saving.
[0002]
[Prior art]
Conventionally, in industrial furnaces such as heating furnaces, heat treatment furnaces, melting furnaces or incinerators, exhaust and combustion are used as a means for high-temperature preheating of combustion air with exhaust gas sensible heat in a combustion apparatus aimed at improving the thermal efficiency of the furnace. A regenerative burner (hereinafter referred to as a regenerative burner) that performs alternately, recovers heat by a heat storage element housed in a heat accumulator during exhaust, and preheats combustion air during combustion is used. The regenerative burner requires a switching valve in each of fuel piping, combustion air piping, and exhaust gas piping because of alternate combustion of combustion and exhaust. Moreover, in an industrial furnace equipped with a regenerative burner, combustion is performed in pairs, so the capacity or number of burners is doubled.
[0003]
Therefore, as a means for solving the problem, a heat recovery combustion apparatus described in Japanese Patent Publication No. 6-56261 has been proposed.
[0004]
[Problems to be solved by the invention]
FIG. 7 is a diagram showing the configuration of the combustion apparatus described in Japanese Patent Publication No. 6-56261. The configuration of this heat recovery type combustion apparatus is such that combustion air passage 40 through which combustion air is disposed in the vicinity of a burner attached to the furnace wall and exhaust gas after combustion are discharged outside the furnace. The exhaust gas passage 42 can rotate between the exhaust gas passage 42 and the combustion air passage 40 so that the combustion air flowing through the combustion air passage 40 is heated by the heat of the exhaust gas flowing through the exhaust gas passage 42. In the combustion apparatus having a heat storage body 41 having a large number of vent holes provided in the air passage 40 and the exhaust gas passage 42 by partitioning the interior with a partition plate 43 in the opening formed in the furnace wall 34. One of the formed ducts 44 is connected, and the heat storage body 41 is arranged in a cylindrical part without the partition plate 43 at the inner end of the duct 44.
[0005]
This heat recovery type combustor has the problem of regenerative burners, that is, the configuration of the regenerative burner is composed of one set of two because the combustion of the regenerative burner is an alternate combustion of combustion and exhaust. Although it has a configuration with an automatic switching valve in the fuel piping, combustion air piping, and exhaust gas piping, the number of burners or the capacity is doubled. There are the following problems.
[0006]
(1) Since the heat accumulator 35 is installed directly on the furnace wall 34 of the industrial furnace, the opening of the furnace wall 34 depends on the dimensions of the heat accumulator 35 and becomes larger, so that the processing range of the burner tile 36 becomes larger. Therefore, the furnace size is restricted by the size of the burner tile 36, and the furnace 37 cannot be made compact.
[0007]
(2) As shown in FIG. 7, the structure of the combustion apparatus is composed of a fuel nozzle 38 and a heat accumulator 35. Since the heat accumulator 35 is directly connected to the inside of the furnace, the combustion air ejection holes 39 to be blown into the furnace It becomes the size of the combustion air passage 40 of the heat accumulator 35 without reducing the area, the ejection speed of the combustion air is slow, the flame becomes a short flame, and the NOx value becomes high. Further, since the fuel nozzle 38 is separated from the combustion air ejection hole 39, there is a possibility that the flame blows off under conditions where the combustibility deteriorates such as when the temperature in the furnace is low when the furnace starts up.
[0008]
(3) The combustion air passage 40 in the heat accumulator 35 narrows the combustion air passage 40 in order to increase the ejection speed of the combustion air into the furnace (the combustion air passage is 1/8 to 1/2 of the entire area). 5), in the heat storage body 41, the time taken by the combustion air and the exhaust gas is different, and the heat recovery rate is deteriorated.
[0009]
(4) A ceramic honeycomb is used for the heat storage body 41, and it is relatively weak against thermal stress and easily cracked.
[0010]
(5) Since the combustion air passage 40 and the exhaust gas passage 42 are directly connected to the heat accumulator 35, a drift occurs in the passage and passes through the heat accumulator 41 as it is. Therefore, it is necessary to make the heat storage body 41 longer than necessary.
[0011]
[Means for Solving the Problems]
In order to solve the above problems, the present invention is summarized as follows.
[0022]
( 1 ) A burner formed by providing a primary air nozzle on the outer periphery of the fuel nozzle and forming a primary combustion port in a baffle provided at the tip of the nozzle is spaced from the furnace wall at a predetermined interval. A plurality of provided heat storage bodies that are rotatable around a shaft center by a driving device are formed inside a cylindrical tube installed outside the furnace by filling a large number of small diameter tubes in the same direction as the shaft center. A buffer portion having a constant space is formed at both ends of the body, and each of the buffer portions is divided into two in the same direction as the axis of the cylindrical tube, and one is an exhaust gas buffer chamber and the other is a combustion air buffer chamber; Further, an exhaust gas passage is connected to the exhaust gas buffer chamber and a combustion air passage is connected to the combustion gas buffer chamber to constitute a rotary heat accumulator, and the rotary heat accumulator is disposed between the burners. Exhaust gas passage located on the furnace side and combustion The air passage and forms as occupying passed, communicating with each furnace via an exhaust gas suction hole and the combustion air nozzle is formed in a furnace wall.
[0023]
( 2 ) The combustion apparatus for an industrial furnace according to claim 1 , wherein an exhaust gas suction hole is provided between the burner and the burner, and at least two combustion air nozzles are arranged on both sides of the suction hole. And at least two combustion air passages located on the furnace side of the rotary heat accumulator are formed so as to communicate with the inside of the furnace via the combustion air nozzle.
[0024]
From ( 1 ), ( 2 ), therefore
Since the rotary heat accumulator is independent of the furnace , the burner tile can be processed freely.
[0025]
It is possible to equalize the combustion air passage cross-sectional area and the exhaust gas passage cross-sectional area in rotary type heat accumulator, combustion air, equal time through the exhaust gas each regenerator, heat recovery in the combustion air preheating of the exhaust gas sensible heat The rate will be good.
[0026]
If you are using small diameter tubes independent thermal storage body, the combustion air to the regenerator, when the respective exhaust gas passes, heating, subjected to thermal stress such cooling. Therefore, since the gap between the small-diameter pipes becomes an expansion allowance at the time of heating, it is strong against this thermal stress, and even if it is partially broken, only that part can be replaced.
[0027]
Cylindrical respectively combustion air buffer chamber at both ends of the regenerator within the tube, also provided an exhaust gas buffer chamber, the combustion air passages, compared with the exhaust gas passage constitute a rapidly expanding portion. Accordingly, combustion air and exhaust gas flowing in from the combustion air passage and the exhaust gas passage are once received in the buffer chamber, and the pressure before and after the heat storage body can be made uniform, so that no drift occurs. The same can be said when the heat storage body passes through the combustion air passage and the exhaust gas passage.
[0028]
Since the combustion air nozzles can be designed independently, free to design the ejection speed of the combustion air, by increasing the ejection speed, by increasing the winding amount in the furnace exhaust gas, the long flame of flame and low NOx conversion can be achieved.
[0029]
By the bar burner tip installing a primary combustion port is flame holder, when the furnace temperature is poor combustion of the burner in use at a low temperature is to increase the amount of primary air, the combustion When the burner becomes more flammable, such as when the furnace temperature is high, the amount of primary air is reduced and the amount of secondary air is increased to increase the heat recovery amount of exhaust gas sensible heat. We will try to reduce it.
[0030]
By eliminating the bus Natairu structure, as compared with the case where there is a normal burner tile, it is possible to increase the exhaust gas entrainment amount, can be a low NOx resistance, elongation of the flame.
[0031]
For installing the rotary regenerator at a rate of one to two bar burner, it can be reduced to half the number of rotary regenerator.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on examples with reference to the drawings.
[0033]
Figure 1 is a schematic view of a combustion apparatus as a reference example of the present invention, a schematic view of a rotary regenerator 8 2 constituting the combustion apparatus as a reference example of the present invention, industrial 3 claim 1 Furnace, FIGS. 4, 5 and 6 are detailed views of the details of FIG.
[0034]
FIG. 1 shows a longitudinal sectional view of a combustion apparatus provided with a rotary heat accumulator 8 and a front view seen from the inside of the furnace, and a reference example of the present invention will be described. The burner 5 has a configuration in which a fuel nozzle 1 is arranged at the center of the burner 5, and a primary air nozzle 2 is arranged around the fuel nozzle 1 so that the fuel nozzle 1 does not become high temperature due to sensible heat of combustion air. In addition, a baffle 3 provided at the tip of the primary air nozzle 2, that is, a primary combustion port 4 for primary combustion flame holding is disposed inside the furnace. Furthermore, around this primary combustion port 4, in this reference example, four combustion air nozzles 6 are equally arranged around the burner 5 axis. Therefore, the combustion air nozzle 6 can be provided at an arbitrary position and number depending on the shape of the baffle 3. A plurality of exhaust gas suction holes 7 are arranged outside the combustion air nozzle 6 so as not to obstruct combustion. Further, the rotary heat accumulator 8 is disposed in the vicinity of the burner 5 and outside the furnace, and the combustion air passage 9 of the rotary heat accumulator 8 and the combustion air nozzle 6 of the burner 5 are connected by a pipe provided with a refractory material. Further, the exhaust gas passage 10 of the rotary heat accumulator 8 and the exhaust gas suction hole 7 of the burner 5 are similarly connected by a pipe provided with a refractory material.
[0035]
The burner 5 is characterized in that the combustion air nozzle 6 is arranged around the fuel nozzle 1, so that the shape of the flame is not biased and the combustion is good. In addition, the primary air is blown into the vicinity of the fuel and the primary combustion port 4 is installed at the same time, which may cause deterioration of combustibility such as when the furnace temperature is low (= combustion air temperature is low). Even in some cases, good combustibility can be maintained. Further, by using air at normal temperature as the primary air, the fuel nozzle 1 is also protected. Furthermore, by adjusting the amount of primary air blown in, the burner 5 can be prevented from starting up a flame when the load is low. Further, by installing the rotary heat accumulator 8 outside the furnace in the vicinity of the burner 5, while performing highly efficient waste heat recovery comparable to that of the regenerative burner, unlike the regenerative burner, all the burners are burned, No fuel switching valve, combustion air switching valve, or exhaust gas switching valve is required. Furthermore, by installing the exhaust gas suction hole 7 in the vicinity of the burner 5, the amount of exhaust gas entrained in combustion can be increased and NOx can be reduced.
[0036]
Next, the rotary heat accumulator 8 which is a reference example of the present invention will be described in detail with reference to the drawings. The rotary heat accumulator 8 is provided with a heat accumulator 25 in the central portion inside the cylindrical tube 11. The heat accumulator 25 is composed of a small-diameter tube 12 filled in the same direction as the shaft center 17 with the shaft center 17 as the center. Rotate freely. FIG. 4 is a cross-sectional view of the heat storage body 17 and the inner wall of the cylindrical tube 11 as seen from above the rotary heat storage unit 8. As shown in the figure, the heat storage body 25 is uneven with respect to the cylindrical tube 11. Accordingly, considering the flow in the circumferential direction, the enlargement / reduction portion is repeated, and the pressure loss increases and the flow becomes difficult. Therefore, mixing of exhaust gas and combustion air can be suppressed to a minimum. FIG. 5 shows the relationship between the shaft center 17 and the heat storage body 25. The shaft center 17 and the heat storage body 25 are in contact with each other without a gap as shown in the figure, and the heat storage body 25 is fixed to the shaft center 17 by bonding between the small diameter pipes 12 with an adhesive or the like. Alternatively, the top and bottom of the heat storage body 25 are fixed with a flange or the like.
[0037]
Buffer portions are formed at both ends of the heat storage body. These buffer portions are divided into two in the same direction as the axis 17 of the cylindrical tube 11 by partition walls 22 and 23, respectively, and one is an exhaust gas buffer chamber 13 and 14 and the other is a combustion air buffer chamber 15 and 16. Yes. Further, exhaust gas passages 10 and 19 made of piping are connected to the exhaust gas buffer chambers 13 and 14, and the exhaust gas passage 10 on the furnace side is connected to the exhaust gas suction hole 7 of the burner 5 by a pipe constructed with a refractory material. The exhaust gas passage 19 is connected to an exhaust gas suction blower by piping. The combustion air buffer chambers 15 and 16 are connected with combustion air passages 9 and 21 made of piping, and the combustion air passage 9 on the furnace side is made up of the combustion air nozzle 6 of the burner 5 and piping constructed of a refractory material. The other combustion air passage 21 is connected to the combustion air blower by piping. The combustion air buffer chamber 16 and the exhaust gas buffer chamber 13 suddenly expand from each passage to each buffer chamber. Further, since the pressure resistance of the heat storage body 25 is large, the pressure is equalized in the buffer chamber and passes through the heat storage body 25. It prevents fluid drift. The combustion air buffer chamber 15 and the exhaust gas buffer chamber 14 are rapidly reduced from each buffer chamber to each passage, and the fluid is rectified in the buffer chamber and flows into each passage, so that the pressure and temperature of the fluid are uniform.
[0038]
FIG. 6 shows a state of the partition walls 22 and 23 between the exhaust gas buffer chambers 13 and 14 and the combustion air buffer chambers 15 and 16. As shown in the figure, the partition walls 22 and 23 are two to three times as thick as the small-diameter pipe 12, and when the small-diameter pipe 12 passes through the partition walls 22 and 23 during heat exchange, the partition walls 22 and 23 cause exhaust gas or combustion. Air is confined in the small-diameter pipe 12 to prevent continuous mixing of exhaust gas and combustion air. The same applies to the partition wall between the exhaust gas buffer chamber and the combustion air buffer chamber.
[0039]
In the heat recovery method of the rotary heat accumulator 8, exhaust gas having a higher temperature than the exhaust gas passage 10 communicating with the inside of the furnace enters the rotary heat accumulator 8 and is rectified in the exhaust gas buffer chamber 13 to form the heat accumulator 25. It flows evenly inside and outside each small diameter pipe 12. Then, heat exchange with the small-diameter pipe 12 is performed, the temperature becomes low, the temperature and pressure of the fluid are equalized in the exhaust gas buffer chamber 16, and the fluid is discharged from the exhaust gas passage 19 to the outside through the exhaust gas suction blower. The heat accumulator 25 that has become hot due to heat exchange rotates about the axis 17 and passes over the partition walls 22 and 23 and moves from the exhaust gas passage side to the combustion air passage side. On the other hand, normal-temperature combustion air is sent to the rotary heat accumulator 8 through the combustion air passage 21 by the combustion air blower, rectified in the combustion air buffer chamber 16, and evenly passes through the small-diameter pipe 12 that is the heat storage body 25. . And the small diameter pipe | tube 12 heated by exhaust gas and high temperature and combustion air exchange heat, and combustion air is preheated to high temperature. The combustion air preheated to a high temperature is rectified in the combustion air buffer chamber 15 to equalize the temperature and pressure, and sent to the burner 5 from the combustion air passage 9. Then, the small-diameter pipe 12 that has become low temperature again rotates around the shaft center 17, moves to the exhaust gas passage side, and performs heat exchange with the exhaust gas again. As described above, the heat storage body 25 is continuously rotated around the axis 17 so that the exhaust gas sensible heat can be continuously recovered. Here, the rotation of the heat storage body 25 is continuously rotating, and the rotation speed thereof is increased in proportion to the flow rate of the combustion air and exhaust gas passing through the heat storage body 25.
According to the above-described reference example, heat recovery is performed continuously with high efficiency, so that all the burners can be burned simultaneously, and a switching valve is not necessary. Moreover, since the burner part is independent of the rotary heat accumulator, the burner can be designed independently.
Furthermore, by using the rotary heat accumulator of this reference example, high-efficiency heat recovery that preheats combustion air to a high temperature can be performed continuously. Moreover, since the heat storage body is composed of an independent small-diameter pipe, the amount of leakage is small and the spalling resistance is good.
[0040]
Next, as an embodiment of the present invention , FIG. 3 shows an image diagram of an industrial furnace provided with a rotary heat accumulator 8 according to claim 1 between burners 30. (A) is a view seen from outside the furnace, (b) is a view seen from inside the furnace, a cross section (c) is a cross sectional view of the burner 30 part, and a cross section (d) is the rotary regenerator 8 and the exhaust gas suction hole 31. It is sectional drawing. In this industrial furnace, the exhaust gas suction hole 31 is arranged in the center between the burners 30 on the furnace wall 33, the combustion air nozzles 32 are arranged on both sides thereof, and they are arranged in the rotary heat accumulator 8 installed outside the furnace. Located on the furnace side. Each nozzle is connected to the exhaust gas passage 10 and the combustion air passage 9 by pipes each constructed with a refractory material. Here, the rotary heat accumulator 8 is arranged as close as possible to the industrial furnace, that is, outside the furnace within 2 m from the furnace wall 33 of the industrial furnace. The burner 30 has a structure in which a fuel nozzle 26 is disposed at the center of the burner 30, a primary air nozzle 27 is disposed around the fuel nozzle 26, a baffle 29 provided at the tip of the nozzle is disposed, and primary combustion is performed inside the furnace. Port 28 is arranged.
[0041]
The feature of this industrial furnace is that the primary combustion port 28, which is a flame holder, increases the amount of primary air when the furnace temperature is low, such as when the furnace temperature is low, to improve the combustibility. When the combustibility is good like a high temperature, the flow rate of the primary air is decreased in order to improve the heat recovery of the low NOx property and the rotary regenerator 8. By eliminating the burner tile structure, the low NOx property and the extension of the flame can be achieved by increasing the amount of exhaust gas entrained. Further, when the furnace height is restricted by the size of the burner as in a conventional burette heating furnace, the exhaust gas suction hole 31 and the combustion air nozzle 32 are arranged in parallel with the burner, and thus the restriction is eliminated. Further, by arranging the exhaust gas suction hole between the burners and the combustion air nozzles on the left and right of the exhaust gas suction hole, unburned fuel is prevented from being sucked from the exhaust gas suction hole.
[0042]
Next, the rotary heat accumulator 8 in the present embodiment will be described. The detailed configuration is substantially the same as that of the rotary heat accumulator in the reference example described above. However, in the case of the present embodiment, as described in claim 2 , by arranging the rotary heat accumulator 8 between the burner 30 and the burner 30, the quantity thereof is compared with the case attached to each burner 30. Half is enough. That is, there are two combustion air passages 9 and one exhaust gas passage 10 communicating with the rotary regenerator 8 and the furnace side, and each one communicating with the combustion blower and the exhaust gas blower. . Since the combustion air passage 9 communicating with the furnace side is disposed symmetrically with respect to the combustion air buffer chamber 15, the combustion air is not biased.
[0045]
【The invention's effect】
Since the industrial furnace provided with the rotary heat accumulator according to claims 1 and 2 has the rotary heat accumulator independently outside the furnace, as compared with the case where one rotary heat accumulator is provided per burner. Can be reduced. Further, by eliminating the burner tile structure, low NOx properties and flame extension can be achieved.
[Brief description of the drawings]
FIG. 1A is a cross-sectional view of a combustion apparatus provided with a rotary heat accumulator, and FIG. 1B is a front view of the combustion apparatus provided with a rotary heat accumulator as viewed from inside a furnace.
FIG. 2 is an image diagram of a rotary heat accumulator.
FIG. 3A is a view as seen from the outside of a part of a furnace wall of an industrial furnace provided with a rotary heat accumulator independently from a burner, and FIG. 3B is a view showing a rotary heat accumulator independent of a burner. The figure seen from the inside of one part of the furnace wall of the industrial furnace, (c) is a sectional view of the burner of the industrial furnace provided with the rotary heat accumulator independently of the burner, and (d) is the burner of the rotary heat accumulator. Sectional drawing of the rotary regenerator of the industrial furnace provided independently.
4 is a diagram showing a relationship (part I) between a heat storage body inside the rotary heat storage device and the outer wall of the heat storage device of FIG. 2;
5 is a diagram showing a relationship (part II) between the shaft center of the rotary heat accumulator of FIG. 2 and a heat accumulator.
6 is a view showing details (part III) of a partition wall in the rotary heat accumulator of FIG. 2;
FIG. 7 is a diagram showing a configuration of a combustion apparatus described in Japanese Patent Publication No. 6-56261.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Fuel nozzle 2 ... Primary air nozzle 3 ... Baffle 4 ... Primary combustion port 5 ... Burner 6 ... Combustion air nozzle 7 ... Exhaust gas suction hole 8 ... Rotary regenerator 9 ... Combustion air passage (communicating with the furnace side) 10 ... Exhaust gas passage (communication with furnace side)
11 ... Cylindrical tube 12 ... Small diameter tube 13 ... Exhaust gas buffer chamber (communication with furnace side)
14 ... Exhaust gas buffer chamber (communication with exhaust gas suction blower)
15 ... Combustion air buffer chamber (communication with furnace side)
16 ... Combustion air buffer chamber (communicating with combustion air blower)
17 ... Center 19 ... Exhaust gas passage (communication with exhaust gas blower)
21 ... Combustion air passage (communicating with combustion air blower)
22: Partition wall (partition of exhaust gas buffer chamber and combustion air buffer chamber)
23 ... Partition wall (partition of exhaust gas buffer chamber and combustion air buffer chamber)
DESCRIPTION OF SYMBOLS 24 ... Drive device 25 ... Heat storage body 26 ... Fuel nozzle 27 ... Primary air nozzle 28 ... Primary combustion port 29 ... Baffle 30 ... Burner 31 ... Exhaust gas suction hole 32 ... Combustion air nozzle 33 ... Furnace wall 34 ... Furnace wall 35 ... Regenerator 36 ... Burner tile 37 ... Furnace 38 ... Fuel nozzle 39 ... Combustion air ejection hole 40 ... Combustion air passage 41 ... Heat storage body 42 ... Exhaust gas passage 43 ... Partition plate 44 ... Duct

Claims (2)

 A burner (1) is provided with a primary air nozzle (27) on the outer periphery of the fuel nozzle (26) and a primary combustion port (28) is formed on a baffle (29) provided at the tip of the nozzle. 30) are provided at predetermined intervals on the furnace wall (33), and can be rotated around a shaft center (17) by a driving device (24) inside a cylindrical tube (11) installed outside the furnace. The heat storage body (25) is formed by filling a large number of small-diameter pipes (12) in the same direction as the axis, and a buffer portion having a constant space is formed at both ends of the heat storage body. Each is divided into two in the same direction as the axis of the cylindrical tube, one is an exhaust gas buffer chamber (13) (14), the other is a combustion air buffer chamber (15) (16). The passages (10) and (19) are connected to the combustion gas buffer chamber through the combustion air. (9) A rotary regenerator is constructed by connecting (21) and (21), and the rotary regenerator is disposed between the burners, and an exhaust gas passage and a combustion air passage located on the furnace side of the regenerator are provided. A combustion apparatus for an industrial furnace characterized in that it communicates with the inside of the furnace through an exhaust gas suction hole (31) and a combustion air nozzle (32) formed in the furnace wall. An exhaust gas suction hole (31) is provided in the furnace wall (33) between the burner (30) and the burner (30), and at least two combustion air nozzles (32) are arranged on both sides of the suction hole. while setting, the combustion air passage located on the furnace side of the rotary regenerator (9) to form at least two, according to claim 1, characterized in that form as communicating with the furnace through the combustion air nozzles Industrial furnace combustion equipment.

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