JP2771763B2 - Combustion superheater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion section, a heat exchange section in which a heat transfer tube is arranged and which guides high-temperature combustion gas generated in the combustion section, and a combustion section which passes the heat exchange section and passes the combustion gas through the combustion section. The present invention relates to a combustion type superheater having an exhaust gas circulation path for returning to a combustion chamber.

[0002]

2. Description of the Related Art As shown in FIG. 5, in a conventional combustion type superheater, a high-temperature combustion gas generated in a combustion section 4 is mixed with an exhaust gas returned through an exhaust gas circulation path 7 to reach a set temperature. By supplying the adjusted combustion gas to the heat exchange unit 5, the temperature of the combustion gas passing through the heat exchange unit 5, that is, the temperature of the exhaust gas, is kept constant.

[0003]

However, when the amount of combustion gas generated in the combustion section 4 is small, the flow of the combustion gas in the heat exchange section 5 is constantly biased, and the heat transfer tube 6 is locally localized. As a result of being excessively heated and corroded, there is a fear that durability may be lacking. In addition, the scale and soot adhere to the surface of the heat transfer tube, resulting in a decrease in thermal efficiency. An object of the present invention is to eliminate the above-mentioned conventional disadvantages.

[0004]

In order to achieve this object, a first feature of the combustion type superheater according to the present invention is to discharge the exhaust gas from the exhaust gas circulation path to the heat exchange section, Is provided with a stirring mechanism for stirring the combustion gas guided to the combustion chamber. Further, a second characteristic configuration is that a cleaning mechanism for ejecting exhaust gas from the exhaust gas circulation path to the heat transfer tube to remove deposits on the heat transfer tube is provided.

[0005]

According to the first feature, even when the amount of combustion gas guided to the heat exchange section is small and a steady deviation occurs, a part of the exhaust gas in the exhaust gas circulation path is stirred by the stirring mechanism. Alternatively, the combustion gas is agitated by ejecting all of the gas to the heat exchange section, thereby achieving uniform heat exchange in the entire heat transfer tube. According to the second characteristic configuration, even if scale or soot adheres to the surface of the heat transfer tube, a part or all of the exhaust gas in the exhaust gas circulation path is ejected to the surface of the heat transfer tube by a cleaning mechanism. By blowing away the scale and soot, the heat exchange efficiency in the heat transfer tubes is improved.

[0006]

According to the first characteristic configuration, even if the amount of combustion gas is small, local overheating of the heat transfer tube due to uneven gas flow in the heat exchange section is prevented, and the durability is excellent. It has become possible to provide a combustion type superheater. According to the second characteristic configuration, it is possible to provide a combustion type superheater excellent in thermal efficiency by removing scale and soot attached to the surface of the heat transfer tube using exhaust gas for circulation. Further, by providing the damper mechanism, it is possible to provide a combustion type superheater having excellent durability and excellent thermal efficiency.

[0007]

Embodiments will be described below. The combustion type superheater according to the present invention is, for example, as shown in FIG. 1, 60 kgf / cm ² , 31 in the waste heat boiler 2 provided in the municipal waste incinerator 1.
It is used to heat the generated steam of 0 ° C. to about 500 ° C. and supply the generated steam to the power generator 3.
And a heat exchange unit 5 for guiding the high-temperature combustion gas generated in the combustion unit 4 and an exhaust gas circulation path 7 for returning the combustion gas passing through the heat exchange unit 5 to the combustion unit 4. It is.

As shown in FIG. 2, the combustion section 4 comprises a combustion burner 4a for burning fuel such as city gas or heavy oil and a combustion chamber 4b, and an exhaust gas recirculation port is provided at a peripheral portion on the upstream side of the combustion chamber 4b. 4c is connected to the exhaust gas circulation path 7. The heat exchange section 5 is configured by arranging a plurality of heat transfer tubes 6 in a flue 5a for guiding the combustion gas in the combustion section 4 in a direction orthogonal to the flow of the combustion gas. 2
The steam generated in the above is guided to the heat transfer tube 6 to be overheated. After the combustion gas that has passed through the heat exchange unit 5 is collected by the electric dust collector 11, a part of the combustion gas is returned to the return port 4c through the exhaust gas circulation path 7, and a part of the combustion gas is used as the combustion gas in the incinerator. 1 and partially exhausted from a chimney (not shown).

That is, about 1800 ° C. generated in the combustion section 4
The exhaust gas returned through the exhaust gas circulation path 7 is mixed with the high-temperature combustion gas before and after the high-temperature combustion gas, and the combustion gas after being adjusted to a set temperature of about 800 ° C. (varies depending on the amount of superheat) is supplied to the heat exchange unit 5. The temperature of the supplied combustion gas passing through the heat exchange unit 5, that is, the temperature of the exhaust gas is maintained at a constant temperature of about 400 ° C., and a part of the gas is efficiently used as the secondary combustion gas of the incinerator 1. aim.

As shown in FIG. 3, an exhaust gas supply passage 8a is provided in the exhaust gas circulation passage 7 at a position on the near side to the recirculation port 4c via a damper 10a at a downstream peripheral portion of the combustion chamber 4b. The stirrer 8 is connected to an annular blower pipe 8b disposed in the heat exchanger 5, thereby forming an agitation mechanism 8 for ejecting exhaust gas to the heat exchange unit 5 and agitating the combustion gas guided to the heat exchange unit 5. An outlet (or a nozzle) 8c for ejecting the supplied exhaust gas so as to generate a swirling flow is formed along the circumference of the annular pipe 8b, and the combustion gas from the burner 4a is formed in the annular pipe 8b. Even when the amount of combustion gas is small, even if the amount of combustion gas is small, the localization of the heat transfer tube 6 due to the unevenness of the gas flow in the heat exchange unit 5 can be achieved by uniformly stirring the gas and supplying the heat to the heat exchange unit 5. Prevents excessive heating, prevents high temperature corrosion and ensures durability.

As shown in FIG. 2, the exhaust gas circulating path 7 is provided with a plurality of blower pipes 9a extending to the flue 5a via a damper 10b, and each blower pipe 9a is provided with the heat transfer pipe 6a. A discharge port (which may be a nozzle) 9b for discharging exhaust gas toward the heat transfer pipe 6 is formed.
The cleaning mechanism 9 that removes the deposits (scale and soot) of the cleaning liquid is constituted.

In a normal state, the dampers 10a and 10b are closed and all of the exhaust gas from the circulation path 7 is circulated to the combustion section 4, but the combustion becomes so large that the gas flow in the heat exchange section 5 becomes uneven. When the amount of combustion gas in the section 4 is small, the opening degree of the damper 10a is adjusted in accordance with the degree thereof (for example, ascertained from the amount of fuel gas or air supplied to the burner 4a) to adjust the stirring mechanism 8 And the damper 10b is closed during the operation of the stirring mechanism 8 to prevent the operation of the cleaning mechanism 9. And, periodically, the damper 10b
To remove the deposits (scale and soot) on the heat transfer tube 6 and collect the dust by the electric dust collector 11, thereby improving the heat exchange efficiency in the heat transfer tube.

Another embodiment will be described below. The superheating condition in the combustion type superheater is not limited to the above numerical values,
It can be set appropriately according to the system used.

Although the case where the combustion type superheater is used for superheating steam in a garbage incinerator has been described, the use is not particularly limited and is arbitrary.

Although the agitating mechanism 8 has been described in which the annular blowing pipe 8b is arranged on the downstream peripheral portion of the combustion chamber 4b, the shape of the blowing pipe 8b and the shape of the injection pipe formed in the blowing pipe 8b are described. The shape of the outlet (which may be a nozzle) 8c is not particularly limited. For example, as shown in FIG. 4, the blower pipe 8b may be formed in a “W” shape in cross section. However, it is necessary to minimize the arrangement that obstructs the combustion gas flow. Further, even if the ejection port (or may be a nozzle) 8c is not formed so as to generate a swirling flow by the exhaust gas discharged from the ejection port 8c, the combustion gas generated in the combustion unit 4 is uniformly stirred. If so, the ejection direction is not particularly limited.

The shape and arrangement of the ventilation pipe 9a constituting the cleaning mechanism 9 are not particularly limited, and may be set as appropriate. In order for the cleaning mechanism 9 to efficiently remove deposits (scale and soot) on the heat transfer tubes 6, the dampers 10b for adjusting the amount of air blown out from each of the ventilation pipes 9a are not opened at the same time, but only one damper 10b. By performing the operation of opening all the dampers 10b in order, the deposits may be removed in a state where the ejection strength is further increased. The control mechanism for performing such an operation can be easily realized by using a known control circuit mechanism.

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 configuration diagram of a garbage incinerator.

FIG. 2 is a longitudinal sectional view of a combustion type superheater.

FIG. 3 is a cross-sectional view of a combustion type superheater.

FIG. 4 is a cross-sectional view of a combustion type superheater showing another embodiment.

FIG. 5 is a longitudinal sectional view of a combustion type superheater showing a conventional example.

[Explanation of symbols]

 Reference Signs List 4 Combustion part 5 Heat exchange part 6 Heat transfer tube 7 Exhaust gas circulation path 8 Stirring mechanism 9 Cleaning mechanism 10 Damper mechanism

Claims (2)

(57) [Claims] 1. A heat exchange part (5), comprising a combustion part (4), a heat transfer tube (6), for introducing high-temperature combustion gas generated in the combustion part (4), and the heat exchange part (5). And a flue gas circulation path (7) for returning the combustion gas passing through the combustion section (4) to the combustion section (4), wherein the exhaust gas in the flue gas circulation path (7) is exchanged with the heat exchange section (5).
A combustion type superheater provided with an agitating mechanism (8) for agitating the combustion gas guided to the heat exchanging section (5). 2. A heat exchange part (5), which is provided with a combustion part (4), a heat transfer tube (6) and guides a high-temperature combustion gas generated in the combustion part (4), and the heat exchange part (5). And a flue gas circulation path (7) for returning the combustion gas passing through the combustion section (4) to the combustion section (4), wherein the flue gas from the flue gas circulation path (7) is sent to the heat transfer tube (6). A combustion type superheater provided with a cleaning mechanism (9) for ejecting the heat transfer tube (6) to remove the deposits.