JPH10267217A - External combustion superheater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably control an external combustion superheater while preventing a vapor flow passage from being superheated and improving heat efficiency with a simplifier construction, the superheater including a vapor superheating passage disposed on a combustion gas flow passage from a combustion chamber and supply air volume adjusting means for adjusting the supply volume of air supplied together with a fuel to the combustion chamber and the superheater being adapted such that vapor from a waste heat boiler of an incinerator to an electric power generation installation can be superheated. SOLUTION: A combustion chamber 1 is divided into a primary combustion chamber 1A and a secondary combustion chamber 1B, and a radiation/heat transfer pipe line 10B communicated with a vapor superheating passage 10A and is disposed so s to surround the primary combustion chamber 1A. A bright frame combustion control part 31 is provided on supply air amount adjusting means 30 for controlling a primary air amount supplied to the primary combustion chamber 1A such that a combustion state in the primary combustion chamber 1A is in the state where air is insufficient. Use of gas fuel is effective as a fuel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an external combustion type superheater, and more particularly, to a method for arranging a steam superheat path in a combustion gas flow path from a combustion chamber and supplying air to the combustion chamber together with fuel. The present invention relates to an external combustion type superheater which is provided with a supply air amount adjusting means for adjusting the temperature and which can superheat steam from a waste heat boiler of an incinerator to a power generator.

[0002]

2. Description of the Related Art Conventionally, in an external combustion type superheater, as shown in FIG. 4, a steam superheat path 10A is arranged in a combustion gas flow path from a combustion chamber 1 so that a combustion chamber provided in the combustion chamber 1 is provided. 4
A superheater control device C for adjusting the amount of fuel supplied to the fuel supply path 5 is provided, and steam from a waste heat boiler of an incinerator is passed through a steam superheater 11 in contact with combustion exhaust gas from the combustion chamber 1. It is configured to overheat.

The combustion chamber 1 has a fuel supply passage 5 connected to a combustor 4.
From the air supply passage 6, and at the same time, combustion air is supplied from the air supply passage 6. A part of the exhaust gas is circulated and a part of the exhaust gas is circulated to the primary combustion chamber 1. The combustion gas is mixed with the combustion gas, and the combustion gas is agitated to promote the contact between the unburned components in the combustion gas and the residual oxygen, thereby causing complete combustion in the secondary combustion chamber 1B.

[0004] The supply amount of the gaseous fuel is determined by the steam supply path 24.
Is set on the basis of the temperature of the steam supplied from the waste heat boiler detected by the temperature detecting section 20a of the inlet steam detecting means 20 and the amount of supplied steam detected by the flow rate detecting section 20b. The fuel adjustment valve 5a is adjusted to be controlled, and the supply amount of the combustion air is controlled by the fuel adjustment valve 5a.
The PID control of the flow control valve 6a is performed in conjunction with the adjustment of the pressure control.

[0005] A cooling mechanism 2a is provided to supply the other part of the circulated combustion gas along the peripheral wall 2 of the combustion chamber 1 as a cooling gas into the room, thereby protecting the peripheral wall from overheating. This is to cool the inner surface of the peripheral wall 2 with the cooling gas and at the same time prevent the combustion gas from coming into contact with the peripheral wall 2, and to guide the cooling gas to the combustion gas flow path to recover cooling heat. It is intended to be. As described above, the circulation of the exhaust gas is intended to reduce the sensible heat of the exhaust gas discharged from the outlet exhaust gas passage 14. For this purpose, an exhaust gas circulation path 15 branched from the outlet exhaust gas path 14 is provided, and the exhaust gas circulation path 15 is fed into the combustion chamber 1 again by the circulation blower 16.

In the superheater S, in order to increase the temperature of the combustion gas as much as possible, the excess air ratio is reduced as much as possible in order to avoid the cooling of the flame by the air, and the heat of the exhaust gas is converted into the combustion air by the air preheater 17. And a part of the circulating exhaust gas from the exhaust gas circulation path 15 is blown into the outlet of the primary combustion chamber 1A as a stirring gas as described above, so that the unburned gas in the primary combustion chamber 1A comes into contact with the remaining oxygen. To complete combustion. For this reason, the secondary combustion chamber 1B
A diffusion mechanism 3 is provided at the inlet of the exhaust gas to enhance the stirring effect of the circulating exhaust gas, and further recovers the sensible heat of the exhaust gas.

The temperature of the combustion gas at the outlet of the combustion chamber 1 is 900
° C or lower, the exhaust gas temperature at the superheater outlet is maintained at about 400 ° C, and the superheated steam temperature at the outlet of the steam superheater 10A is set to 500 ° C.
℃, the wall temperature of the steam superheater 11
It is configured to keep it at about ° C. For this purpose, the combustion control device C is provided, and the combustion gas temperature at the outlet of the combustion chamber 1 detected by the combustion gas temperature detecting means 18 provided at the outlet of the combustion chamber 1 and the combustion gas flow path at the outlet of the superheater are provided. Exhaust gas temperature detected by the temperature detector 19a of the disposed exhaust gas detector 19 and the exhaust gas flow rate detected by the flow rate detector 19b, and the temperature and flow rate detector of the supplied steam detected by the temperature detector 20a of the inlet steam detector 20 20b, the temperature of the outlet superheated steam detected by the temperature detector 21a of the outlet steam detector 21 disposed at the outlet of the steam superheater 10A, and the flow detector 2 provided in the cooling gas passage 22.
2b and flow rate detecting means 23 provided in diffusion gas channel 23
b, the exhaust gas circulating amount detected is input, and the flow rate adjusting valve 6a provided in the air supply path 6, the flow rate adjusting valve 15a provided in the exhaust gas circulating path 15, and the exhaust gas circulating path 15, which guides the cooling gas. The cooling gas flow path 22 and the flow rate adjusting valve 23a provided in the branched gas flow path 23 are configured to be adjusted.

[0008]

The above-mentioned conventional external combustion type superheater has a problem that when the amount of steam supplied from the waste heat boiler through the steam supply passage 24 decreases, the temperature of the superheated steam becomes too high. Therefore, when the flow rate detector 20b of the inlet steam detector 20 detects a decrease in the flow rate,
While measures to reduce the amount of fuel supplied to the combustor 4 and at the same time to reduce the temperature of the combustion gas by supplying excess air can be considered, even if the combustion gas is diluted and cooled by the excess air,
It is difficult to rapidly lower the tube wall temperature, and if excess air is supplied, the amount of exhaust gas increases, resulting in an increase in heat loss due to sensible heat brought by the exhaust gas.

Therefore, the applicant adds water from the water supply mechanism 13A constituting the water addition mechanism 13 to the steam in the steam superheater 10A within a range where the dryness is not excessively reduced. When the temperature detection unit 21a detects that the temperature rises more than necessary, water is further added to the steam in the steam superheating path 10A from the temperature reduction mechanism 13B, which is another component of the water addition mechanism 13, and the superheated steam temperature is increased. (Japanese Patent Application No. 4-115).
623). However, the temperature of the superheated steam increases sharply,
In particular, when the amount of steam at the inlet is sharply reduced, the water added from the water addition mechanism increases the wetness of the steam, so that problems such as erosion of the inner wall of the steam superheater tube 11 are likely to occur. Therefore, the above countermeasure has a fast control response,
The problem remains that the effective operation range of the countermeasure is narrow.

In order to improve the thermal efficiency, the exhaust gas is circulated and supplied along the inner surface of the peripheral wall 2 of the combustion chamber 1 instead of the conventional water-cooled wall structure, so that the combustion gas is diluted and cooled by the circulated exhaust gas. A chamber cooling mechanism 2a has been proposed (Japanese Patent Application No. 8-60651). However, even if it is cooled by the circulating exhaust gas, the point that it is difficult to rapidly lower the tube wall temperature of the steam superheater 11 similarly to the addition of the excess air described above has not been solved. Moreover, simultaneous control of the cooling of the combustion gas and the addition of the water results in a problem that the control response is poor in spite of the complicated control, and that it is difficult to settle in a short time. That is, the water addition mechanism 13 has a problem in that the control response is fast, while the decrease in the fuel supply amount tends to cause a delay in the control response due to a large thermal inertia in the superheater. Accordingly, an object of the present invention is to provide an external combustion type superheater capable of solving the above problems and preventing overheating of a steam flow path, increasing thermal efficiency with a simple structure, and performing stable control. I do.

[0011]

[Means for Solving the Problems]

[First characteristic configuration] According to a first characteristic configuration of the external combustion type superheater of the present invention for the above purpose, as described in claim 1, the combustion chamber is divided into a primary combustion chamber and a secondary combustion chamber. And a radiant heat transfer pipe communicating with the steam superheat passage, and disposed so as to surround the primary combustion chamber, and the supply air amount adjusting means includes a primary air amount supplied to the primary combustion chamber. Is provided with a bright flame combustion control unit for controlling the combustion state in the primary combustion chamber to an insufficient air state. [Effects of First Feature Configuration] According to the first feature configuration, the heat input and the combustion chamber exit temperature are changed only by changing the brightness of the flame while suppressing the cooling loss of the wall of the combustion chamber. It is possible to adjust the superheated steam outlet temperature without the need. In other words, since the radiant heat transfer pipe is arranged so as to surround the primary combustion chamber, overheating of the wall can be prevented by the radiant heat transfer pipe, and the gas shortage can be prevented by changing the air shortage rate of the primary combustion chamber. Even with fuel, the brightness of the flame can be adjusted and the amount of radiant heat transfer can be changed, so that the steam temperature at the superheater outlet can be stably controlled without delay. Moreover, since the amount of radiant heat transfer can be maintained high, even when the wetness of the inlet steam of the radiant heat transfer pipe becomes high, it is possible to evaporate quickly, and the influence of the wetness of the steam can be suppressed. . At this time, since the temperature is adjusted only by the change in the amount of primary air, the flame temperature of the primary combustion chamber hardly changes, and the temperature of the combustion gas after the secondary combustion also changes little. It is possible. Therefore, even if the temperature at the inlet of the steam path changes, or if the steam flow rate at the inlet of the steam path changes greatly, it is possible to cope with this with a margin. For example, when the temperature at the outlet of the steam superheat path is extremely reduced, the supply air amount adjusting means is operated to increase the fuel supply amount, and at the same time, increase the luminance of the flame in the primary combustion chamber to increase the radiant heat transfer amount. If the bright flame combustion control unit is operated, the superheated steam temperature at the radiant heat transfer pipe outlet can be maintained high. Also,
For example, when the amount of supplied steam at the inlet of the steam passage is reduced, the temperature of the steam at the outlet of the superheated steam passage becomes higher even when the amount of supplied fuel is reduced by operating the supply air amount adjusting means. If the bright flame combustion control unit is operated so as to lower the brightness of the flame of the radiant heat transfer pipe, the temperature difference between the entrance and the exit of the radiant heat transfer pipe can be reduced. It is possible to prevent overheating of the wall and to stabilize the superheated steam temperature at the outlet of the radiant heat transfer pipe. This control of the brightness of the flame is particularly effective for gaseous fuels, but even when using liquid fuels,
The brightness of the flame can be adjusted by adjusting the atomization of the liquid fuel, and the adjustment of the brightness of the flame is further facilitated by using the liquid fuel and the gaseous fuel together. As a result, stable control is possible while preventing overheating of the steam flow path and increasing thermal efficiency with a simple structure.

[Second characteristic configuration] The second characteristic configuration of the external combustion type superheater of the present invention is that, as set forth in claim 2, combustion is performed using gaseous fuel as the fuel in the first characteristic configuration. This facilitates the adjustment of the brightness of the flame as described above. In other words, gas fuel, which is a gaseous fuel, burns completely in a blue flame if burned with excess air, and has a very low thermal emissivity, whereas if burned in a lack of air state, the flame turns yellow, The bright flame starts to burn. By taking advantage of the large change in the brightness of this flame,
The radiant heat transfer coefficient can be easily changed, and there is no delay in the control response. As a result, overheating of the steam flow path can be easily prevented, and control stability can be improved. [Third characteristic configuration and operation and effect] According to a third characteristic configuration of the external combustion type superheater of the present invention, the exhaust gas from the superheater outlet is supplied to the combustion chamber in the first characteristic configuration. An exhaust gas circulation path that can be circulated and supplied is provided, so that the superheated steam outlet temperature can be changed with respect to the inlet steam temperature without changing the combustion gas flow rate in the combustion gas flow path. In other words, the incinerator is 2
Even though it is a continuous operation for 4 hours, the power demand fluctuates day and night, so at night when the power demand falls, the superheated steam outlet temperature is lowered and the fuel supply is reduced while using the steam from the waste heat boiler as it is. The exhaust gas from the exhaust gas circulation path is introduced into the combustion chamber while recovering the sensible heat of the exhaust gas at the outlet of the superheater and supplementing the combustion gas flow rate to prevent a decrease in the heat transfer coefficient in the steam superheat path. I can do it. Naturally, since the heat input decreases, the superheated steam outlet temperature decreases. As a result, it is possible to suppress the generator output without increasing the heat loss.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the above-mentioned external combustion type superheater of the present invention will be described below with reference to the drawings. In addition, regarding the same element as the element described in the above conventional technology and the element having the same function,
The same reference numerals as in FIG. 4 are used, and a part of the detailed description is omitted.

As shown schematically in FIG. 1, the external combustion type superheater S is provided with a steam superheater 1 in a combustion gas flow path from the combustion chamber 1.
0A and a radiant heat transfer pipe 10B along the peripheral wall 2 of the combustion chamber 1.
0B is connected to the steam superheating path 10A, the inlet thereof is connected to a steam path from a waste heat boiler of an incinerator, and the supplied steam is superheated and the outlet of the radiant heat transfer pipe 10B is connected to a power generator. Are connected to each other.

The combustion chamber 1 comprises a primary combustion chamber 1A and a secondary combustion chamber 1B formed above the primary combustion chamber 1A. The primary combustion chamber 1A is provided with a combustor 4 that mixes gaseous fuel such as natural gas or the like supplied with air and ignites to form a combustion flame in the primary combustion chamber 1A. The fuel supply passage 5 and the primary air passage 7 are connected to the vessel 4. The primary air passage 7 is connected to the air supply passage 6 via a primary air regulating valve 7a.
The secondary air passage 8 is branched from between the flow control valve 6a and the primary air control valve 7a to supply secondary air to the boundary between the primary combustion chamber 1A and the secondary combustion chamber 1B. It is configured in. The total amount of combustion air is adjusted by the flow control valve 6a in accordance with the required air amount determined in this manner, and the primary air amount is adjusted in accordance with the insufficient air ratio set to make the combustion flame bright. It is configured to be adjusted by the valve 7a. A forced blower 9 is provided in the air supply path 6.
Supply air for combustion.

The steam superheat path 10A is formed by a steam superheat pipe 11 arranged in a combustion gas flow path above the secondary combustion chamber 1B so as to be able to contact the combustion gas from the combustion chamber 1. The radiant heat transfer pipe 10 </ b> B is provided on the peripheral wall 2 of the combustion chamber 1.
A plurality of radiant heat transfer tubes 12c arranged in the vertical direction along the peripheral wall 2 and arranged in the circumferential direction along the peripheral wall 2 are connected to the lower steam inlet side by a distribution pipe 12a, and the plurality of radiant transfer tubes are connected. The steam outlet side above the heat pipe 12c is the collecting pipe 1
It is formed as a radiant heat transfer tube group 12 connected by 2b,
The steam inlet side of the distribution pipe 12a is connected to the steam superheating path 10A.
The flow passage is connected to the steam outlet side of the steam superheater 11 constituting the above. Further, a water addition mechanism 13 for adding water to the steam in the flow path is disposed in the steam flow path 10 connecting the steam superheated pipe 11 and the radiant heat transfer pipe group 12. The steam inlet side of the steam superheater 11 serves as a steam inlet of the superheater S, and the steam outlet side of the collecting pipe 12b serves as a superheated steam outlet of the superheater S. The radiant heat transfer tube group 12 includes a plurality of radiant heat transfer tubes 12.
c may be disposed separately from the inner surface of the peripheral wall 2, or the plurality of radiant heat transfer tubes 12 c may be connected to each other and formed on a membrane wall to form the inner surface of the peripheral wall 2. You may have.

A combustion gas temperature detector 18 for detecting the temperature of the combustion gas is provided at the outlet of the secondary combustion chamber 1B, and a temperature detector for detecting the temperature of the exhaust gas from the combustion gas passage at the outlet of the superheater S. An exhaust gas detecting means 19 is provided which includes a flow sensor 19a for detecting the flow rate of the exhaust gas.
Further, an inlet steam detecting means 20 having a temperature detecting section 20a for detecting the temperature of the inlet steam and a flow rate detecting section 20b for detecting the flow rate is provided at the steam inlet, and the temperature of the outlet superheated steam is detected at the superheated steam outlet. An outlet steam detecting means 21 having a temperature detecting section 21a is provided. Then, the amount of fuel supplied to the combustor 4 is adjusted based on inputs from the combustion gas temperature detecting means 18, the exhaust gas detecting means 19, the inlet steam detecting means 20, and the outlet steam detecting means 21. The fuel control valve 5a, the primary air control valve 7a for adjusting the primary air supply amount to the combustor 4, and the superheater control device C for controlling the water addition mechanism 13 are provided.

The combustion control device C includes a supply air amount adjusting means 30 for adjusting an air supply amount with respect to a fuel supply amount supplied to the combustor 4, and further includes the radiant heat transfer tube group. In order to adjust the amount of radiant heat transfer to the radiant heat transfer tube 12c that constitutes the blast tube 12, a bright flame combustion control unit 31 that adjusts the amount of primary air supplied to the combustor 4 is provided.

The above-described external combustion type superheater S is controlled by the superheater control device C as follows. First, the temperature and flow rate of the inlet steam detected by the inlet steam detecting means 20 are input to the superheater control device C to calculate the required heat quantity, determine the fuel supply amount, and adjust the fuel regulating valve 5a.
When the detected inlet steam flow rate is low, the required water addition amount is calculated, and the water addition amount to the water addition mechanism 13 is adjusted. At the same time, based on the detection result of the flow meter 5b for detecting the fuel supply amount to the combustor 4, the supply air amount adjusting means 3
With 0, the flow control valve 6a provided in the air supply path 6 is proportionally controlled. Next, the outlet steam detector 21 is provided to the bright flame combustion controller 31 of the supply air amount controller 30.
In order to adjust the brightness of the flame in the primary combustion chamber 1A so as to maintain the temperature at 500 ° C. by inputting the outlet superheated steam temperature detected by the temperature detecting section 21a, a required insufficient air ratio is calculated, and the primary air regulating valve is adjusted. Adjust 7a. Further, the superheater control device C corrects the opening of the flow regulating valve 6a of the air supply passage 6 so that the combustion gas temperature detected by the combustion gas temperature detecting means 18 is maintained at 900 ° C. Next, based on the temperature of the exhaust gas detected by the temperature detecting section 19a of the exhaust gas detecting means 19, the opening of the fuel control valve 5a and the flow control valve 6a is corrected and controlled.

With the above configuration, in the external combustion type superheater of the present invention, the control response characteristic of the combustion gas temperature and the exhaust gas temperature with respect to the control by the combustion control device C is improved, and the control delay of the outlet superheated steam temperature is reduced. Restrained,
As a result of the matching of the overall control, control of the superheater with a fast settling was realized. Furthermore, as a result of forming the final superheating stage in the vertical radiant heat transfer tube group 12, the amount of water added from the water addition mechanism 13 becomes excessive, and the steam supplied to the vertical radiant heat transfer tube group 12 becomes wet steam. Even if the temperature rises, superheated steam can be generated without any problem. In particular, even if the water level increases in the radiant heat transfer tubes 12c due to an increase in moisture, the vertical radiant heat transfer tube group 12 functions as an evaporation tube. Moreover, since the total pipe area of the radiant heat transfer tube 12c can be made larger than the other steam flow paths, the steam flow rate can be reduced, so that the heat transfer amount per unit volume can be kept high, and furthermore, Erosion caused by the wetness of the steam can also be prevented.

Next, another embodiment of the present invention will be described. <1> In the above-described embodiment, an example in which the radiant heat transfer pipes 10B are arranged along the peripheral wall 2 of the combustion chamber 1 has been described, but the radiant heat transfer pipe group 12 constituting the radiant heat transfer pipes 10B A part may be arranged in the combustion chamber 1. <2> In the above-described embodiment, an example is shown in which the radiant heat transfer pipe 10B is arranged along the peripheral wall 2 of the combustion chamber 1; however, the radiant heat transfer pipe 10B is a peripheral wall 2 having only the primary combustion chamber 1A. May be arranged along the peripheral wall 2 extending from the combustion chamber 1 to the combustion gas flow path. <3> In the above embodiment, an example is shown in which the combustion chamber 1 is constituted by the primary combustion chamber 1A and the secondary combustion chamber 1B formed above the primary combustion chamber 1A. As shown in FIG. <4> In the above embodiment, the radiation heat transfer pipe 10B
An example in which a steam path is connected to a steam superheat path 10A, a steam path from a waste heat boiler of an incinerator is connected to an inlet of the steam superheat path 10A, and a steam path to a power generator is connected to an outlet of the radiant heat transfer pipe 10B. However, a steam superheater 10A is further connected to the outlet of the radiant heat transfer pipe 10B, so that the radiant heat transfer pipe 10B
A steam path to the power generator may be connected to the downstream steam superheat path 10A outlet. <5> In the above embodiment, the radiation heat transfer pipe 10B
Are arranged in a vertical posture along the peripheral wall 2 of the combustion chamber 1,
Further, the lower steam inlet side of the plurality of radiant heat transfer tubes 12c arranged in the circumferential direction along the peripheral wall 2 is connected by a distribution pipe 12a, and the upper steam outlet side of the plurality of radiant heat transfer tubes 12c is assembled. Although the example formed as the radiant heat transfer tube group 12 connected by the tube 12b was shown, for example, as shown in FIG.
The radiant heat transfer pipe 12c formed in a spiral shape is
B may be configured. With this configuration, the radiant heat transfer pipe 12c is used as the radiant heat transfer pipe 10B, and the cross section of the flow path is made larger than that of the steam flow path 10, so that the residence time of the steam can be increased. The effect can be effective. The radiant heat transfer tube 12 c may be arranged separately from the inner surface of the peripheral wall 2, or may be embedded in the inner surface of the peripheral wall 2. Further, the radiant heat transfer tube 12c may be formed by a plurality of pipes arranged in parallel.
The spiral radiant heat transfer pipe 10B is arranged in the steam flow direction (as a counter flow) opposed to the combustion gas flow direction, but is arranged in the opposite direction (as a parallel flow). Is also good. <6> FIG. 2 shows an example in which the secondary air passage 8 is provided with the secondary air adjustment valve 8a instead of providing the primary air passage 7 with the primary air adjustment valve 7a. In the embodiment shown in FIG. 1, it is also possible to arrange the adjustment valve as shown in FIG. Here, as shown in FIG. 2, the water addition mechanism 13 includes a water supply mechanism 13A disposed in the inlet-side steam flow path 10 of the steam superheat path 10A, and an inlet-side steam flow path 10A to the radiant heat transfer pipe 10B. And the temperature reduction mechanism 13B arranged in the first position. Furthermore, although the external combustion type superheater S has been exemplified as a vertical type, the external combustion type superheater S may be a horizontal type, and as shown in the prior art, a type in which the combustor 2 is arranged in a horizontal direction. Good. <7> In the above embodiment, the water addition mechanism 13 that adds water to the steam in the flow path is disposed in the steam flow path 10 that connects the steam superheated pipe 11 and the radiant heat transfer pipe group 12. Although an example has been shown, the water addition mechanism 13 may not be provided. That is, when there is no request to keep the outlet superheated steam amount constant, the bright flame combustion control unit 31 of the supply air amount adjustment unit 30 does not use the water addition mechanism 13 as a superheated steam temperature reduction mechanism. This is because it is possible to prevent overheating of the radiant heat transfer tube 12c by adjusting the brightness of the combustion flame in the primary combustion chamber 1A. The bright flame combustion control section 31 may be independent of the supply air amount adjusting means 30. Further, the supply air amount adjusting means 30 may be independent of the superheater control device C. <8> In the above-described embodiment, the example in which the gas fuel is burned in the combustor 2 has been described. However, the fuel burned in the combustor 2 may be a liquid fuel. The combustion flame surely turns into a bright flame. The brightness of the combustion flame may be adjusted by adjusting the spray particle diameter, by adjusting the preheating temperature of the liquid fuel, or by adjusting the amount of secondary air blown. <9> The external combustion superheater S connects the exhaust gas circulation path 15 branched from the outlet exhaust gas path 14 to the air supply path 6 to circulate the exhaust gas and supply the exhaust gas to the combustion chamber 1, as shown in FIG. You may have. In this way, a part of the heat energy discharged with the exhaust gas can be recovered, the flame temperature in the combustion chamber 1 can be reduced, and the combustion gas flow rate can be maintained even when the fuel supply amount is reduced. Therefore, for example, when nighttime power demand falls, steam from the waste heat boiler is heated to a relatively low temperature and supplied to the generator, and the waste heat of the incinerator is effectively used while suppressing heat loss. Becomes possible. In addition, this exhaust gas circulation path 15 may be connected to the primary air path 7, and in this case,
The temperature of the primary combustion flame is reduced while maintaining the heat transfer in the steam superheat path 10A, and the amount of radiant heat transfer to the radiant heat transfer pipe 10B is reduced, so that the superheated steam outlet temperature can be reduced. Further, the exhaust gas circulation path 15 may be connected to the secondary air path 8, so that the temperature of the combustion gas can be reduced without lowering the temperature of the primary combustion flame. Steam superheat path 10A
When the temperature of the steam from the furnace decreases or the steam flow rate decreases, the superheated steam outlet temperature can be adjusted with good control responsiveness by adjusting the brightness of the primary combustion flame.

In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the configuration shown in the attached drawings.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an example of an external combustion superheater according to the present invention.

FIG. 2 is a schematic view illustrating another example of the external combustion superheater according to the present invention.

FIG. 3 is an explanatory view of another example of the external combustion type superheater according to the present invention.

FIG. 4 is an explanatory view showing an example of a conventional external combustion type superheater.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Combustion chamber 1A Primary combustion chamber 1B Secondary combustion chamber 10A Steam superheating path 10B Radiation heat transfer pipe 15 Exhaust gas circulation path 30 Supply air adjusting means 31 Bright flame combustion control section

Claims (3)

[Claims] 1. A supply air amount control for arranging a steam superheat path (10A) in a combustion gas flow path from a combustion chamber (1) and adjusting a supply amount of air supplied together with fuel to the combustion chamber (1). An external combustion type superheater comprising means (30) and configured to be able to superheat steam from a waste heat boiler of an incinerator to a power generation device, wherein the combustion chamber (1) is a primary combustion chamber (1A). The radiant heat transfer pipe (1) is divided into a secondary combustion chamber (1B) and communicates with the steam superheat path (10A).
0B) is formed and disposed so as to surround the primary combustion chamber (1A), and the supply air amount adjusting means (30) is provided with the primary air amount supplied to the primary combustion chamber (1A) by the primary air amount. Combustion chamber (1
An external combustion superheater provided with a bright flame combustion control section (31) for controlling the combustion state in A) to an insufficient air state. 2. The external combustion type superheater according to claim 1, wherein the fuel is burned using gaseous fuel as the fuel. 3. The external combustion type superheater according to claim 1, further comprising an exhaust gas circulation path (15) capable of circulating and supplying exhaust gas from a superheater outlet to the combustion chamber (1).