JP7036622B2 - Utilization of existing boiler High steam condition boiler plant - Google Patents

Description

The present invention relates to a high steam condition boiler plant utilizing existing boiler equipment.

In recent years, in the technical field of power plants, development for advanced-ultra-supercritical thermal power generation (A-USC: Advanced-Ultra Super Critical) has been promoted in order to further improve power generation efficiency.

For example, Patent Document 1 describes an A-USC plant whose target is a main steam temperature and a reheated steam temperature higher than those of a USC plant having a main steam temperature of about 600 ° C.

Japanese Unexamined Patent Publication No. 2013-13370

However, the invention described in Patent Document 1 does not consider the economical construction of the A-USC plant, and there is room for improvement in this respect. That is, in order to realize A-USC, it is necessary to raise the temperature of the superheated steam supplied to the steam turbine higher than the current temperature, and it has more heat transfer surface and more heat transfer surface than the conventional steam temperature boiler plant. High-temperature materials that can handle higher temperatures are required, but at the same time, reduction of construction costs is required from the viewpoint of overall economic efficiency. When constructing a high steam condition plant, in addition to the case of new construction, when the existing boiler plant is diverted because there are many parts that can be diverted, such as the furnace, low temperature heat transfer surface, combustion device, steel frame, duct, auxiliary equipment, etc. However, it is often difficult to add a heat transfer surface for improved steam conditions to the existing boiler due to space saving and restrictions on adjusting the overall heat absorption balance. Construction costs put pressure on economic efficiency and are difficult to establish.

Therefore, an object of the present invention is to provide an existing boiler utilization high steam condition boiler plant capable of economically constructing an A-USC plant by utilizing the existing boiler equipment.

In order to achieve the above object, the present invention combines an existing boiler with an independent superheater separately placed on the steam system as a means for increasing the temperature of steam conditions while diverting the equipment of the existing boiler as much as possible to generate superheated steam. The system should be exchanged with each other. That is, a part or all of the low temperature steam of the existing boiler is extracted, a steam cooling wall of the independent superheater is constructed, and then the steam is returned to the existing boiler. Further, the outlet steam of the final superheater or the final reheater of the existing boiler is introduced into the heat transfer surface in the separately installed independent superheater by diverting the existing main piping material to increase the heating temperature.

Specifically, it was composed of a boiler equipped with multiple stages of boiler-side superheated steam heat exchangers in the combustion gas passage, and a steam cooling wall cooled by the first superheated steam introduced from the boiler. The furnace and flue, a burner provided in the steam cooling wall to inject fuel into the furnace and burn, and a second superheated steam introduced from the boiler and having a temperature higher than that of the first superheated steam. An independent superheater equipped with an independent superheater-side superheated steam system heat exchanger that exchanges heat with the combustion gas in the furnace and the flue to further heat, and a steam turbine driven by superheated steam derived from the independent superheater. And, the superheated steam outlet of the first superheated steam heat exchanger selected from the multi-stage boiler side superheated steam heat exchanger and the superheated steam inlet of the steam cooling wall are connected by a pipe. , The superheated steam outlet of the steam cooling wall and the superheated steam inlet of the second superheated steam heat exchanger whose steam temperature is higher than that of the first superheated steam heat exchanger are connected by a pipe, and further, the above It is characterized in that the superheated steam outlet of the second superheated steam heat exchanger and the superheated steam inlet of the independent superheater side superheated steam heat exchanger are connected by a pipe.

According to the present invention, A-USC can be economically realized with a relatively simple configuration by making the best use of the existing boiler equipment. In addition, the high-temperature main piping that guides the heated steam to the high-pressure steam turbine uses a special material with high high-temperature strength, which greatly affects economic efficiency. The installation position of the independent superheater has a high degree of freedom, and the ultra-high temperature piping to and from the high-pressure steam turbine can be optimally and shortestly arranged, which is highly effective in improving economic efficiency. Further, since the steam pressure loss can be minimized by minimizing the pipe length, it is also effective in improving the power generation efficiency. Issues, configurations and effects other than those described above will be clarified by the description of the embodiments described below.

It is a block diagram of the power plant which concerns on 1st Example. It is a block diagram of the power plant which concerns on 2nd Example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings for each example.

[First Example]
FIG. 1 shows the configuration of the power plant 1A according to the first embodiment. As is clear from this figure, the power generation plant 1A according to the first embodiment has a boiler 1, an independent superheater 2, a high-pressure steam turbine 3 driven by superheated steam supplied from the independent superheater 2, and a high pressure. It includes a generator 4 driven by a steam turbine 3.

The boiler 1 is a so-called conventional boiler such as a coal-fired boiler, an oil-fired boiler, and a gas-fired boiler, and has a furnace 12 provided with a burner 11 and an exhaust gas passage 13 leading to the furnace 12. In the exhaust gas passage 13, the economizer 14, the primary superheater 15, the secondary superheater 16, the tertiary superheater 17, the primary reheater 18, the secondary reheater 19 and the tertiary reheater 20 Are arranged in a predetermined arrangement. In the present specification, the primary superheater 15, the secondary superheater 16, the tertiary superheater 17, the primary reheater 18, the secondary reheater 19, and the tertiary reheater 1 provided in the boiler 1 are used. The vessels 20 are collectively referred to as "boiler-side superheated steam heat exchangers".

As the boiler 1, an existing boiler is used. The boiler 1 burns coal, oil (heavy oil or light oil), gas, etc. injected from the burner 11 in the furnace 12.

The combustion gas generated in the furnace 12 is guided into the exhaust gas passage 13, the secondary superheater 16, the tertiary superheater 17, the primary reheater 18, the secondary reheater 19, the primary superheater 15, and the primary superheater 15. After exchanging heat with superheated steam or water supply in the economizer 14, flying ash and the like are removed by entering a smoke exhaust treatment facility (not shown). Exhaust gas from which fly ash and the like have been removed is released into the atmosphere through a chimney and the like (not shown).

The independent superheater 2 includes a furnace and a flue composed of a steam cooling wall 21 cooled by the first superheated steam introduced from the boiler 1, a burner 22 that injects fuel into the furnace and burns, and smoke. The heat in the steam cooling wall 21 and the independent superheater side superheated steam heat exchanger 23, which is arranged in the path and exchanges heat with the combustion gas in the flue to further heat the second superheated steam introduced from the boiler 1. It is provided with a heat recovery unit 24 for recovering the above. In the first embodiment, a superheater is provided as the superheated steam system heat exchanger 23 on the independent superheater side. In the following description, the independent superheater side superheated steam heat exchanger 23 is referred to as "independent superheater side superheater 23".

As shown in FIG. 1, in the first embodiment, the superheated steam outlet 15a of the primary superheater 15 provided in the boiler 1 and the superheated steam inlet 21b of the steam cooling wall 21 constituting the independent superheater 2 are used. Is connected by a pipe 31, and the superheated steam outlet 21a of the steam cooling wall 21 and the superheated steam inlet 16b of the secondary superheater 16 provided in the boiler 1 are connected by a pipe 32. Further, the superheated steam outlet 17a of the tertiary superheater 17 provided in the boiler 1 and the superheated steam inlet 23b of the independent superheater side superheater 23 provided in the independent superheater 2 are connected by a pipe 33 and become independent. The superheated steam outlet 23a of the superheater side superheater 23 and the superheated steam inlet 3b of the high-pressure steam turbine 3 are connected by a pipe 34. Further, the water supply pipe 35 that supplies water to the economizer 14 and the water supply inlet 24b of the heat recovery unit 24 provided in the independent superheater 2 are connected by a pipe 36 to the water supply outlet 24a of the heat recovery unit 24. , The outlet pipe 37 of the economizer 14 and the outlet pipe 37 are connected by a pipe 38. Therefore, a second superheated steam having a temperature higher than that of the first superheated steam introduced into the steam cooling wall 21 is introduced into the independent superheater side superheater 23.

The combustion gas generated in the independent superheater 2 exchanges heat with the superheated steam in the superheater 23 on the independent superheater side and the water supply in the heat recovery unit 24, and then is shown exclusively for the independent superheater or attached to the boiler 1. No flying ash or the like is removed by entering the smoke exhaust treatment facility, and the exhaust gas from which the flying ash or the like is removed is discharged to the atmosphere through a chimney or the like (not shown) dedicated to the independent superheater or attached to the boiler 1. The boiler 1 and the independent superheater 2 may share the flue gas treatment equipment.

The burner 22 burns using coal, gas or oil as fuel. In this case, in order to simplify the configuration of the fuel supply system provided in the boiler 1 and the independent superheater 2, it is desirable to share the fuel of the boiler 1 and the fuel of the independent superheater 2. That is, when the boiler 1 is a coal-fired boiler, the burner 22 burns coal, and when the boiler 1 is a gas-fired boiler, the burner 22 burns gas, and the boiler 1 is an oil-fired boiler. In some cases, the burner 22 burns the oil. When gas is used as the fuel, temperature control becomes easy and the problem of high temperature corrosion does not occur.

The independent superheater side superheater 23 exchanges heat with the combustion gas in the steam cooling wall 21 for the second superheated steam extracted from the tertiary superheater 17 of the boiler 1, further superheats it, and supplies it to the high-pressure steam turbine 3. .. Since the independent superheater 2 is a device independent of the boiler 1, the installation position of the independent superheater 2 has a high degree of freedom, and the ultra-high temperature piping between the independent superheater 2 and the high-pressure steam turbine 3 can be optimally arranged in the shortest time. .. Therefore, compared to the case where the superheated steam derived from the boiler 1 is directly supplied to the high-pressure steam turbine 3, the pipe length of the pipe 34 manufactured by using an expensive material can be minimized, and the existing boiler utilization high steam condition can be achieved. It greatly contributes to improving the economic efficiency of boiler plants. It is also effective in improving power generation efficiency because steam pressure loss can be minimized by minimizing the pipe length.

The heat recovery unit 24 recovers the preheat in the steam cooling wall 21 after superheating the independent superheater side superheater 23, and heats the water supply supplied from the economizer 14 to the furnace 12.

Since the power plant 1A according to the first embodiment is configured as described above, the superheated steam that has passed through the primary superheater 15 is introduced into the steam cooling wall 21 through the pipe 31. Further, the superheated steam that has passed through the steam cooling wall 21 is introduced into the secondary superheater 16 of the boiler 1 through the pipe 32, and is combined with the exhaust gas in the exhaust gas passage 13 in the secondary superheater 16 and the tertiary superheater 17. It is heat exchanged and overheated. Further, the superheated steam that has passed through the tertiary superheater 17 of the boiler 1 is introduced into the independent superheater side superheater 23 through the pipe 33, and is further heated by exchanging heat with the combustion gas in the independent superheater 2. .. On the other hand, a part of the water supply in the water supply pipe 35 that supplies water to the economizer 14 is introduced into the heat recovery unit 24 of the independent superheater 2 through the pipe 36, and the combustion gas in the independent superheater 2 is introduced. It is heated by heat exchange with. The water supply that has passed through the heat recovery unit 24 is introduced into the outlet pipe 37 of the economizer 14 through the pipe 38.

As described above, in the power generation plant 1A according to the first embodiment, the independent superheater 2 provided with the steam cooling wall 21 is attached to the boiler 1, and the superheated steam extracted from the primary superheater 15 of the boiler 1 is independently superheated. Since it is sequentially introduced into the steam cooling wall 21 of the vessel 2, the secondary superheater of the boiler 1, the tertiary superheater of the boiler 1, and the superheater 23 on the independent superheater side of the independent superheater 2, it is superheated. In comparison, the steam temperature of the superheated steam supplied to the high-pressure steam turbine 3 can be increased. Therefore, the power generation plant 1A according to the first embodiment can improve the power generation efficiency as compared with the power generation plant provided with the conventional boiler device.

According to the power plant 1A according to the first embodiment, by newly installing an independent superheater 2 while utilizing the existing boiler 1, it is possible to construct an A-USC utilizing the existing power plant. Therefore, the power generation plant 1A according to the first embodiment can make effective use of resources and reduce the cost of the power generation plant having high power generation efficiency, as compared with the case where the existing boiler 1 is dismantled and the A-USC boiler is newly installed. Can be built.

[Second Example]
FIG. 2 shows the configuration of the power plant 1B according to the second embodiment. As is clear from this figure, in the power plant 1B according to the second embodiment, a reheater 51 is provided in the independent superheater 2 instead of the independent superheater side superheater 23, and the high-pressure steam turbine 3 is provided. Instead, a low pressure steam turbine 52 is provided. In the second embodiment, the reheater provided in the independent superheater 2 is referred to as "independent superheater side reheater 51".

In the power generation plant 1B according to the second embodiment, the superheated steam outlet 21a of the steam cooling wall 21 and the superheated steam inlet 18b of the primary reheater 18 provided in the boiler 1 are connected by a pipe 32. ing. Further, the superheated steam outlet 20a of the tertiary reheater 20 provided in the boiler 1 and the superheated steam inlet 51b of the independent superheater side reheater 51 are connected by a pipe 53 and reheated on the independent superheater side. The superheated steam outlet 51a of the heater 51 and the superheated steam inlet 52b of the low-pressure steam turbine 52 are connected by a pipe 54. Since other configurations are the same as those of the power plant 1A according to the first embodiment, the same reference numerals are given to the corresponding portions, and the description thereof will be omitted.

Since the power plant 1B according to the second embodiment is configured in this way, the temperature of the superheated steam supplied to the low-pressure steam turbine 52 can be raised by the independent superheater side reheater 51, and the power generation efficiency can be increased. It can be improved.

The scope of the present invention is not limited to the scope described in Examples 1 and 2, and the constituent elements of the invention described in Examples 1 and 2 are modified without departing from the spirit of the present invention. Also included are those in which the components of the invention described in Examples 1 and 2 are replaced with well-known components, and those in which Examples 1 and 2 are appropriately combined.

For example, in the first embodiment, the independent superheater side superheater 23 is provided as the independent superheater side superheater steam system heat exchanger, and in the second embodiment, the independent superheater side superheater steam system heat exchanger is provided. Although the reheater 51 is provided, both the independent superheater side superheater 23 and the independent superheater side reheater 51 may be provided in the steam cooling wall 21. Further, in Examples 1 and 2, the boiler 1 is provided with a primary superheater 15, a secondary superheater 16 and a tertiary superheater 17, and a primary reheater 18 and a secondary reheater 19. The number of superheaters and reheaters provided in the boiler 1 is not limited to this, and can be changed as appropriate.

1A, 1B ... Power plant, 1 ... Boiler, 2 ... Independent superheater, 3 ... High-pressure steam turbine, 4 ... Generator, 11 ... Burner, 12 ... Fire furnace, 13 ... Exhaust passage, 14 ... Economizer, 15 ... 1 Secondary superheater, 16 ... secondary superheater, 17 ... tertiary superheater, 18 ... primary reheater, 19 ... secondary reheater, 20 ... tertiary reheater, 21 ... steam cooling wall, 22 ... Burner, 23 ... Independent superheater side superheated steam heat exchanger, 24 ... Heat recovery unit, 31, 32, 33, 34, 36, 38 ... Piping, 35 ... Water supply pipe, 37 ... Economizer outlet piping, 41 ... piping, 42 ... flow control valve, 51 ... independent superheater side reheater, 52 ... low pressure steam turbine, 53, 54 ... piping, 61 ... piping, 62 ... flow control valve

Claims (8)

An existing boiler equipped with multiple stages of superheated steam heat exchangers on the boiler side in the combustion gas passage,
A furnace and flue composed of a steam cooling wall in which the combustion gas system is independent from the existing boiler and cooled by the first superheated steam introduced from the existing boiler, and the inside of the furnace provided in the steam cooling wall. A burner that injects fuel into the boiler and burns, and a second superheated steam introduced from the existing boiler and having a temperature higher than that of the first superheated steam are exchanged with the combustion gas in the furnace and the flue to further overheat. Independent boiler with an independent superheater equipped with a superheated steam heat exchanger on the side
A steam turbine driven by superheated steam derived from the independent superheater, and
Equipped with
The superheated steam outlet of the first superheated steam heat exchanger selected from the multi-stage boiler-side superheated steam heat exchanger and the superheated steam inlet of the steam cooling wall are connected by a pipe and at the same time.
The superheated steam outlet of the steam cooling wall and the superheated steam inlet of the second superheated steam heat exchanger whose steam temperature is higher than that of the first superheated steam heat exchanger are connected by a pipe.
Further, the existing boiler utilization high steam condition is characterized in that the superheated steam outlet of the second superheated steam heat exchanger and the superheated steam inlet of the independent superheater side superheated steam heat exchanger are connected by a pipe. Boiler plant. The first superheated steam heat exchanger is a primary superheater, and the second superheated steam heat exchanger is another superheater having a higher steam temperature than the primary superheater. The existing boiler utilization high steam condition boiler plant according to claim 1. The first superheated steam heat exchanger is a primary superheater , and the second superheated steam heat exchanger is a reheater having a higher steam temperature than the primary superheater . The existing boiler utilization high steam condition boiler plant according to claim 1, which is characterized. The high steam condition boiler plant utilizing an existing boiler according to claim 1, wherein the fuel is coal. The high steam condition boiler plant utilizing an existing boiler according to claim 1, wherein the fuel is a gas. The high steam condition boiler plant utilizing an existing boiler according to claim 1, wherein the fuel is oil. The high steam condition for utilizing an existing boiler according to claim 1, wherein the independent superheater is newly installed in the vicinity of the existing boiler, and the existing boiler and the newly installed independent superheater are connected by necessary piping. Boiler plant. The high steam condition boiler plant utilizing an existing boiler according to claim 1, wherein the outlet steam temperature of the superheated steam system heat exchanger on the independent superheater side is 650 ° C. or higher.

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