JP3180050B2 - Heat recovery type combustion apparatus and control method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat recovery type combustion apparatus in which heat of exhaust gas after combustion is used for heating combustion air, and a control method thereof.

[0002]

2. Description of the Related Art In order to save energy, industrial furnaces such as forging furnaces, normalizing furnaces, and refining furnaces, and combustion devices used for heating devices for steam generation of turbines, etc. 2. Description of the Related Art A heat recovery type combustion device that heats combustion air by using heat of exhaust gas is often used.

[0003] A recuperator used in this type of combustion apparatus generally has a predetermined heat exchanger disposed between an exhaust gas line and a combustion air line provided in close proximity to each other. Heat is exchanged between the air flowing inside and the exhaust gas, and the heat of the exhaust gas after combustion is used to heat the combustion air. The heat recovered by the use of this recuperator is about 50% when viewed at the temperature level.
In the case of using exhaust gas of ℃, the combustion air after heat exchange is assumed to be about 600 ℃. Recuperators are significantly limited in space as well as in their constituent materials, and sometimes take up more space than the body of a furnace or heating device.

Accordingly, the present applicant has recently proposed a combustion apparatus (see Japanese Patent Application Laid-Open No. 1-222102) as shown in FIGS. The combustion device 10 includes a main body R such as a furnace.
A burner 12 for heating an object W to be heated is provided, and a heat storage body 22 made of air-permeable ceramics having a cylindrical outer shape and partitioned into a honeycomb shape is provided on a furnace wall near the burner 12. I have. The heat accumulator 22 stores the heat when the high-temperature exhaust gas in the main body R is discharged out of the furnace.
The combustion air flowing through the air passage 19 is heated by this heat.
Is rotated by the motor M via the rotary shaft 23, so that the heat supply to the combustion air is continuously performed.

[0005]

However, this combustion apparatus 10 has a heat storage body 22 facing a main body R where the temperature becomes high.
Must be provided between the rotating shaft 23 and the motor M, or a heat insulating means for blocking the heat transmitted from the heat storage body 22 to the motor M via the rotating shaft 23 is provided. It is necessary to install the device at a distance so that the body 22 has no thermal influence. If such a means is applied, the size of the combustion device 10 becomes large and the overall configuration becomes complicated. In addition, the heat storage body 22 of the combustion device 10 includes:
Since it becomes high temperature during operation and cools down during operation and becomes low temperature, expansion and contraction are repeated even with ceramics, but if the ceramic heat storage body expanded and contracted in this way is fixed to the rotating shaft and rotated, It is difficult to increase the size, and it is difficult to obtain a fuel having a high combustion capacity that requires a large amount of combustion air and exhaust gas. Furthermore, since it is difficult to provide a burner at the center of the rotating heat storage body, which is repeatedly expanded and contracted, the burner and the air passage are separated from each other, and the size or sharpness of the flame radiated from the burner is increased. However, there is a problem in that the flexibility of adjustment such as control is reduced, and the range of controllability or versatility is reduced.
In order to improve the controllability and the like of the burner, it is possible to use various electric control devices. However, if such devices are used, the cost of the entire apparatus increases, which is not preferable.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems associated with the prior art, and has a simple structure, has flexibility in flame formation, can be made large, has a high energy saving effect and high safety. It is an object of the present invention to provide a heat recovery type combustion device having a long life and a control method thereof.

[0007]

According to the heat recovery type combustion apparatus of the present invention which achieves the above object, a burner and a burner provided at a substantially central position and a fuel pipe for supplying fuel to the burner pass through the substantially central position. And a mechanism (flow path rotating mechanism) that is disposed on the side opposite to the side on which the burner of the heat storage body is disposed and that allows combustion air and exhaust gas to flow through the heat storage body. I do. The mechanism is configured such that combustion air and exhaust gas flow around the fuel pipe while flowing around the fuel pipe along the fuel pipe.

When the heat recovery type combustion device of the present invention is provided in the combustion device main body, the burner heats the object to be heated in the combustion device main body. Then, the heat storage body is fixed to the combustion device main body. A mechanism (passage) that is arranged on the side opposite to the side where the burner of the regenerator is arranged, and rotates an air passage through which combustion air flows and an exhaust gas passage through which exhaust gas flows around the burner with respect to the regenerator. Rotation mechanism). This mechanism is configured such that combustion air passes through the regenerator from the air passage and flows into the combustion device main body, and exhaust gas passes through the regenerator and passes through the exhaust gas passage. Further, the mechanism may have a rotating duct in which a duct through which combustion air flows and a duct through which exhaust gas flows are arranged concentrically around the fuel pipe. In that case,
If one duct located inside is rotated, the other duct located outside is fixed, and a seal member is arranged between one duct and the other duct to allow rotation of one duct. Good. In this way, a seal between the two ducts can be easily and reliably realized. Further, it is preferable that the motor used as the rotary drive source of the mechanism is disposed outside the rotary duct and radially outside the fuel pipe. In this way, it is possible to prevent the motor from being exposed to a high temperature to shorten its life, and to reduce the length of the device.

When the burner extends through a substantially central position of the heat storage body as in the present invention, the air passage and the exhaust gas passage have a cross-sectional area of a portion of the heat storage body through which the exhaust gas passes. It is preferable that the cross-sectional area be larger than the cross-sectional area of the heat storage body through which the air passes. By doing so, the flow velocity of the combustion air can be increased, the fuel can be suppressed from being discharged together with the exhaust gas, the incomplete combustion of the fuel can be suppressed, and the generation of CO can be suppressed. .

In this manner, during operation of the combustion device,
The regenerator is heated by the width radiant heat generated by the combustion and the high-temperature exhaust gas flowing through the exhaust gas passage, and is cooled when the regenerator is stopped, but since the regenerator is fixed to the combustion device body, There is no problem even if a relatively large product is formed, and a product having a high combustion capacity can be obtained with a simple configuration. Then, by rotating the combustion air and the exhaust gas passing through the heat accumulator without rotating the heat accumulator, more specifically, by rotating the air passage and the exhaust gas passage side, the gas is discharged from the air passage. The combustion air is heated when flowing through the heated regenerator, the high-temperature exhaust gas flowing through the exhaust gas passage heats the regenerator, and even if the regenerator is cooled by the combustion air, the rotation of the ducts As a result, the combustion air is successively led to the high-temperature heat storage portion, so that the temperature of the combustion air does not decrease, and the combustion action performed by the high-temperature combustion air is also performed in an extremely high-temperature region.
The time required to reach a predetermined high temperature from the start of combustion is short.

Further, since the burner is provided at a substantially central position of the heat storage body, during combustion, the combustion air is blown out toward the periphery of the flame formed by the burner, and flows upward from the flame radiated from the burner. Promotes complete combustion of fuel while regulating displacement.

In addition, if an air pipe for supplying motive air to the burner is arranged along the fuel pipe to supply motive air to the air pipe in the fuel pipe, the motive air will power the fuel. Therefore, the size or sharpness of the flame radiated from the burner can be adjusted, the flexibility of the flame is increased, and the range of controllability or versatility is increased.

When controlling the heat recovery type combustion apparatus by the method of the present invention, the combustion air and the exhaust gas (or the air passage and the exhaust gas passage) are rotated at a rotation speed of 1 rpm to 3 rpm. Is preferred. By doing so, the preheated air temperature can be raised to some extent. In particular, when the rotation speed is set to a high speed of 2 rpm or more, the preheated air temperature can be kept high and excellent thermal efficiency can be obtained.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view of a heat recovery type combustion apparatus according to one embodiment of the present invention, FIG. 2 is a sectional view taken along line 2-2 of FIG. 1, and FIG. 3 shows a main part of FIG. That
FIG. 3 is a sectional view taken along line 3-3 in FIG. 2. In FIG. 1, a heat recovery type combustion device 30 is attached to a lower portion of a combustion device main body 31 composed of, for example, a forging furnace, and is used as a heat source for heating an object to be heated such as an ingot provided inside the main body 31. Is done.

The heat recovery type combustion apparatus 30 is provided with the main body 3
Burner 32 that emits a flame toward the object to be heated in 1
An air passage 33 provided in the vicinity of the burner 32 and through which combustion air flows, and an exhaust gas provided in the vicinity of the air passage 33 and exhausting burned exhaust gas to the outside of the main body 31 It has a passage 34 (see FIG. 2) and a heat exchange member 35 that transfers the heat of the exhaust gas to the combustion air flowing through the air passage 33.

The combustion device main body 31 is made of, for example, a refractory material such as a refractory brick, and has an opening 31a formed in a side wall. The heat exchange member 35 is provided inside the opening 31a. The heat exchange member 35 is made of a ceramic honeycomb-shaped air-permeable heat accumulator 37,
The heat storage body 37 is supported by a mortar part 36 provided between the heat storage body 37 and the opening 31a. The burner 32 is provided at the center of the heat storage body 37, and the tip thereof faces the inside of the combustion device main body 31. This burner 32
Is a normal gas or oil burner, and combustion air is blown from an air passage 33 through a heat storage body 37 provided so as to surround the burner 32. Therefore, since the combustion air is ejected from the periphery of the burner 32, a side effect of preventing the flame of the burner 32 from being displaced upward by the combustion air itself is produced. .

A plate 38 for supporting the burner 32 is provided at the outer edge of the opening 31a. A flange 40 of the burner body case 39 is connected to the plate 38 by a bolt 41 via a gasket G. The burner body case 39 and the heat storage body 37 are connected so as to communicate with each other.

The burner body case 39 has an air inlet 42 for introducing combustion air through a blower or the like, an outlet 43 for discharging exhaust gas to the outside, and the air inlet 42.
Rotating duct 44 provided between the heat storage 37
And a drive unit 45 for rotating the rotating duct 44.

A large diameter portion 44a of a rotating duct 44 is provided in the body 43a of the outlet 43. The large-diameter portion 44a is a part of the air passage 33, and has a cross section of an acute fan shape as shown in FIG. In the body portion 43a, the air passages 33 and the exhaust gas passages 34 are provided so as to be alternately arranged in the circumferential direction.
a denotes an air passage 33, and a portion between which the cross section is obtuse fan-shaped is an exhaust gas passage 34. With such a configuration, the cross-sectional area of the exhaust gas passage 34 through which the exhaust gas passes becomes larger than the cross-sectional area of the air passage 33 through which the combustion supply air passes. In other words, the cross-sectional area of the portion of the regenerator through which the exhaust gas passes becomes larger than the cross-sectional area of the portion of the regenerator through which the combustion air passes. By doing so, the flow velocity of the combustion air can be increased, the fuel can be suppressed from being discharged together with the exhaust gas, the incomplete combustion of the fuel can be suppressed, and the generation of CO can be suppressed. .

In this example, the air passage 33 and the exhaust gas passage 3
4 is formed to be an independent passage from the inlet to the outlet. For example, the air passage 33 is
The air flowing from the small diameter portion 44 of the rotary duct 44
b through the large-diameter portion 44a that is gradually expanded.
It flows out toward 7. In particular, in the air passage 33 of this embodiment, the end on the side of the heat storage 37 is closed by an end plate 48 having a large number of small holes 47. The exhaust gas to be leaked from between the heat storage body 37 and the rotating duct 44 is drawn into the air passage 33 by the Venturi effect caused by the flow, thereby suppressing the amount of the leaked exhaust gas. ing.

The exhaust gas passage 34 is configured to guide the exhaust gas discharged from the heat storage body 37 to the internal space 43b of the body 43a at the outlet 43 through a portion having an obtuse fan-shaped cross section. .

The drive unit 45 includes an inner end of a closing plate 49 provided to close an end of the body 43 a on the side opposite to the heat storage body at the outlet 43, and a right end of a small-diameter portion 44 b of the rotating duct 44. The rotating duct 44 is rotatably supported by a seal member S and a bearing J provided on the inner end of a support plate 50 provided on the motor, and a sprocket 51 and a motor M fixed between the bearings J, J. And a drive gear 52 rotated by a shaft 53 connected via a chain 53. The motor M is arranged outside the fuel pipe 58 in the radial direction.

As described above, in this embodiment, the rotating duct 4
4 is well-balanced by the two bearings J, J, the rotating duct 44 can be rotated at a relatively high speed, and the higher the rotating speed, the higher the thermal efficiency. The relationship between the rotational speed of the rotating duct 44 and the thermal efficiency was examined by an experiment, and the result is as shown in FIG.

In the experiments, when LPG was used as a fuel and the combustion was performed using the combustion apparatus of the present embodiment, the temperature of exhaust gas, the temperature of preheated air, and the temperature in the furnace with respect to the rotation speed of the rotating duct 44 were measured. Was measured. FIG.
Is the rotation speed of the rotating duct 44, and the vertical axis is the temperature.

According to the experimental results, if the rotation speed of the rotating duct 44 is 1 rpm or less, the temperature of the exhaust gas rises rapidly, and if it exceeds 1 rpm, the rate of decrease in the temperature of the exhaust gas is small. It turned out to be. That is, 1r.p.
It was found that the preheating temperature could be maintained to some extent higher than m.

Here, the thermal efficiency can be obtained from the relationship between the amount of heat input and the amount of heat loss of the exhaust gas, and is given by the following equation.

Η = (Q−Cp · GT) · 100 / Q where, η: thermal efficiency Q: heat capacity of LPG gas Cp: specific heat of exhaust gas G: amount of exhaust gas T: temperature of exhaust gas The thermal efficiency is determined by substituting the results obtained by the above experiment into the above. For example, if the rotation at a relatively high speed of 2 rpm is selected, the corresponding exhaust gas temperature is 250 ° C. Therefore, the thermal efficiency at this time is η = (25000−0.32 · 26 · 250) × 100/2500 = 91.68 (%), and it is clear that excellent thermal efficiency exceeding 90% is exhibited.

As described above, when the rotation speed of the rotating duct 44 is increased, the heat storage body does not significantly decrease in temperature due to the air discharged from the rotating duct 44 when the rotating speed of the rotating duct 44 is increased. Since it is heated by the exhaust gas in the state, the temperature of the intake air can be made higher, so that it is considered that the thermal efficiency will be improved.

The air inlet 42 is formed by connecting a base pipe 54 and a branch pipe 55 in an inverted T-shape. One end of the base pipe 54 is closed by a lid 56 and the other end is connected to the rotating duct. The small-diameter portion 44 b is attached to the support plate 50 so as to communicate with the reference 44. In addition, the code | symbol "57" in FIG. 1 is a current plate.

Further, a fuel pipe 58 for supplying fuel to the burner 32 is provided along the central axis of the rotating duct 44, and the burner 3 is provided in the fuel pipe 58.
Air pipe 59 supplying motive air to 2
(Shown in FIG. 3) is provided, and the size or sharpness of the flame radiated from the burner 32 is adjusted by adjusting the amount of motive air discharged from the air pipe 59. As shown in FIG. 4, the amount of the motive air is suitably about 2 to 5% in relation to the flame sharpness and the heat loss of the theoretical amount of air. By adjusting the motive air, the flexibility, controllability or versatility of the flame can be increased.

The air passage 33, as shown in FIG.
Without extending to the end face of the ceramic heat storage body 37,
A gap t may be provided between the heat storage body 37 and the ceramic heat storage body 37, and the gap t may be used as the communication portion 60 in which a part of the exhaust gas flows by bypassing as indicated by a broken arrow in the drawing. In this case, a part of the exhaust gas is sucked into the air passage 33 again and recombusted.
The amount of NOx in the exhaust gas can be adjusted. In particular, as described above, if high-speed combustion air is discharged using the large number of small holes 47 formed in the end plate 48 of the rotating duct 44, it becomes easier to reburn part of the exhaust gas. .

Next, the operation of the embodiment will be described. The heat recovery type combustion device 30 is attached to a forging furnace, and the burner 32 is ignited while rotating the motor M, and the combustion air is blown by a blower. The fuel flow injected from the burner 32 through the fuel pipe 58 is supplied with oxygen by the combustion air flowing through the air passage 33 and the heat accumulator 37 and becomes a flame to be a flame, for example, an ingot or the like to be heated. Stretch toward you. Then, the temperature in the forging furnace gradually increases, and after a predetermined time elapses, the ingot in the forging furnace is heated and softened.

In this case, the exhaust gas flows out of the exhaust gas passage 34 through the heat accumulator 37. Since the heat accumulator 37 is heated by the flow of the exhaust gas and has a high temperature, the heat accumulates. When the combustion air discharged from the rotating air passage 33 flows into the body 37, the combustion air is heated by the heat storage body 37.

This heating is of an immediate heating type, in which air is blown out from the air passage 33 toward the heat storage body 37 and the combustion air is immediately heated. That is, there is no heat loss at the time of heating. Air can be produced efficiently, and the combustion action performed by the high-temperature heated air is also performed in an extremely high-temperature region, and the time required to reach a predetermined high temperature from the start of combustion is short. Since the exhaust gas is transferred from the exhaust gas passage 34 through the outer periphery of the air passage 33 through which relatively low-temperature air flows after the heat transfer to the regenerator 37, the chimney is not necessarily required.

If a part of the exhaust gas passes through the communicating part 60 between the rotating duct 44 and the ceramic heat storage 37 during combustion, a part of the exhaust gas mixes with the air in the air passage 33. And burned again, the N contained in the exhaust gas
Ox emission can be suppressed to a predetermined value or less. Further, by providing the communication portion 60, the space between the air passage 33 and the exhaust gas passage 34 is not unnecessarily sealed, so that the structure of the entire device is simplified and the assemblability of the device is improved. There are also benefits.

FIG. 6 shows still another embodiment of the combustion apparatus according to the present invention, in which the combustion apparatus 30 is connected to a radiant tube 61 so that exhaust gas is not discharged into a furnace or the like. 61, and heats the object to be heated only by the ambient temperature.
It is intended to be discharged from. Therefore, although the structure is the same as that described above, the clean combustion device 30 is obtained.

The present invention is not limited to a furnace such as the above-described forging furnace, but may be applied to various other apparatuses, for example, a drying apparatus, a steam generating apparatus for a turbine, and so on. Can also be used. In the above-described embodiment, the air passage 33 and the exhaust gas passage 3
4 are formed by dividing the inside of the rotating duct 44, but the present invention is not limited to this, and a large number of air passages and exhaust gas passages may be formed. Further, although an air duct for supplying motive air is provided at the center of the rotating duct 44, this duct is not necessarily provided.

[0038]

As described above, according to the present invention, since the rotating duct is rotated and the heat storage body is fixed, the heat storage body can be increased in size, and a combustion device having a large capacity can be obtained. be able to. Further, since a burner is provided at a substantially central position of the heat storage body, complete combustion of fuel is promoted, and NOx is reduced.
Can be reduced or controlled. Further, since the burner is provided substantially at the center of the heat storage body, it is possible to promote complete combustion of the fuel while restricting upward displacement of the flame radiated from the burner. In addition, if motive air is supplied to the air pipe in the fuel pipe, the size or sharpness of the flame radiated from the burner can be adjusted, increasing the flexibility of the flame and improving controllability or versatility. The width is also large.

Further, according to the control method of the present invention, it is possible to increase the temperature of the preheated air, thereby increasing the thermal efficiency.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a heat recovery type combustion apparatus according to one embodiment of the present invention.

FIG. 2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is a detailed view of a main part of FIG. 1;

FIG. 4 is a view showing control characteristics of a motive air amount.

FIG. 5 is a graph showing experimental results of the present invention.

FIG. 6 is a schematic sectional view showing still another embodiment of the present invention.

FIG. 7 is a schematic sectional view showing a conventional combustion device.

FIG. 8 is an enlarged sectional view of a main part of FIG. 7;

[Explanation of symbols]

 31 Combustion device main body 32 Burner 33 Air passage 34 Exhaust gas passage 35 Heat exchange member 37 Heat storage 39 Burner main body case 44 Rotating duct 45 Rotating means 47 Small hole 48 End plate 58 Fuel pipe 59 Air pipe 60 Communication part t Gap

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A 64-15041 (JP, U) JP 3-30683 (JP, Y2) (58) Fields surveyed (Int. Cl. ⁷ , DB name) F23L 15/02 F23D 14/66

Claims (4)

(57) [Claims] 1. A burner (32) for heating a body to be heated in a combustion device main body (31), and a fuel pipe (58) provided with the burner at a substantially central position and supplying fuel to the burner. A ventilating heat storage element (37) penetrating a position, and an air passage through which combustion air flows and an exhaust gas through which exhaust gas flows are disposed on a side of the heat storage element opposite to a side where the burner (32) is disposed. A mechanism for rotating a gas passage around the fuel pipe with respect to the heat storage body, wherein the heat storage body (37) is fixed to the combustion device body (31); Air passes through the heat storage body (37) from the air passage (33) and passes through the combustion device main body (3).
1) and the exhaust gas flows into the heat storage body (37).
Through the exhaust gas passageway (34) , the mechanism comprising the combustion air around the fuel pipe.
And the duct through which the exhaust gas flows are concentric
With the rotating ducts arranged in parallel and located inside
Is rotated, and the other duct located outside is rotated.
Is fixed, and the one duct and the other duct
Between the two ducts to allow rotation of the one duct.
A heat recovery type combustion device, wherein a heat recovery member (S) is disposed . 2. The air passage and the exhaust gas passage such that a cross-sectional area of a part of the heat storage body through which the exhaust gas passes is larger than a cross-sectional area of a part of the heat storage body through which the combustion air passes. The heat recovery type combustion apparatus according to claim 1 , wherein the combustion apparatus is configured. 3. It is used as a rotary drive source for the mechanism.
The motor (M) is provided outside the rotating duct and the fuel
The pipe according to claim 1, which is disposed radially outside the pipe.
Heat recovery type combustion device. 4. A heating target in the combustion device main body (31) is heated.
A heating burner (32) , wherein the burner is provided at a substantially central position and the burner is provided;
Fuel pipe (58) for supplying fuel to
The heat-storing body (37) having air permeability and the side of the heat- storing body on which the burner (32) is arranged are opposite to each other.
Are arranged on opposite sides, the air passage and the exhaust flow combustion air
The exhaust gas passage through which gas flows is centered on the fuel pipe.
; And a mechanism for rotating with respect to the heat storage body Te, the heat storage body (37) to said combustion device main body (31)
And the mechanism is such that the combustion air flows from the air passage (33).
After passing through the heat storage body (37), the combustion device body (3
1) and the exhaust gas flows into the heat storage body (37).
Through the exhaust gas passage (34).
A heat recovery type combustion device , wherein an air pipe (59) for supplying motive air to the burner is arranged along the fuel pipe.