JP6810378B2 - Garbage power generation system - Google Patents

Description

The present invention relates to a waste power generation system, and more particularly to a steam turbine power generation system using combustion energy of waste incineration.

As a waste power generation system installed in a cleaning factory or the like, a system in which a steam turbine power generation device is connected to a waste heat boiler of a waste incinerator is generally known. The efficiency of such a waste power generation system is improved mainly by increasing the temperature and pressure of steam conditions, and a system equipped with a superheater that superheats steam from a boiler to a high temperature is known (see Patent Document 1 below). ). As the superheater, there are a method of installing it in a waste heat boiler and a method of using the waste heat of the gas turbine by installing a gas turbine.

Japanese Unexamined Patent Publication No. 9-4420

To improve the efficiency of the waste power generation system using a superheater, the steam conditions are set to high temperature and high pressure of 3 to 4 MPa · g and 300 to 400 ° C to improve the power generation end efficiency, but the steam temperature is increased. Has the advantage of improving power generation end efficiency, but has the problem of increasing the risk of high temperature corrosion of boilers (superheater tubes, etc.). Garbage, which is the fuel for power generation, has the property of containing chlorine (Cl). This chlorine content becomes hydrogen chloride (HCl) in the combustion process, and it is known that hydrogen chloride causes severe high-temperature corrosion on boiler tubes and superheated tubes in the region where the steam temperature is 300 ° C. or higher. This high temperature corrosion also occurs when the chlorine content is low.

For this reason, in the waste incineration boiler, the steam temperature is generally limited. However, in recent years, there have been an increasing number of cases in which high-efficiency power generation is aimed at by setting the steam conditions to about 4 MPa / g and 400 ° C. by using an expensive corrosion-resistant material for the superheat tube. In such a case, even if an expensive corrosion-resistant material is used, the high-temperature corrosion itself cannot be eliminated. Therefore, in order to realize stable continuous operation for a long period of time, it is inevitable to replace the superheat tube regularly. There is a problem that a large amount of repair costs are required.

An object of the present invention is to deal with such a problem. In other words, when achieving high efficiency of the waste power generation system, it is possible to eliminate the risk of high temperature corrosion of the boiler, enable continuous operation of the highly efficient and stable waste power generation system without requiring a large repair cost, etc. Is the subject of the present invention.

In order to solve such a problem, the waste power generation system according to the present invention has the following configurations.

A boiler heated by waste heat from waste incineration and a steam turbine power generation device driven by steam from the boiler are provided, and the steam turbine power generation device has a temperature of about 270 ° C., which is a temperature at which high-temperature corrosion does not occur from the boiler. A high-pressure turbine to which the following steam is supplied, a medium-low pressure turbine to which the exhaust of the high-pressure turbine is supplied, and a water supply path for returning the exhaust of the medium-low pressure turbine to the boiler are provided. Exhaust is supplied to the medium-low pressure turbine via a dehumidifier, and the water supply path is provided with a water supply heater to which steam extracted from the medium-low pressure turbine is supplied, and the boiler is provided with a superheater. The boiler and the inlet of the high-pressure turbine are connected by a steam path that does not have a superheater, and a part of the steam from the boiler reheats the exhaust of the high-pressure turbine. A waste power generation system characterized by being used as a heat source for boilers.

In the waste power generation system having such characteristics, steam at a temperature that does not cause high temperature corrosion is supplied from the boiler to the high pressure turbine, so that the risk of high temperature corrosion of the boiler can be eliminated, and the exhaust of the high pressure turbine is a dehumidifier. Since the water supply is heated by the steam extracted from the medium-low pressure turbine and supplied to the medium-low pressure turbine via the above, high-efficiency power generation can be performed without raising the steam temperature to a high temperature.

It is explanatory drawing which showed the main part of the waste power generation system which concerns on embodiment of this invention. It is explanatory drawing which showed the flow sheet of the cleaning plant to which the waste power generation system which concerns on embodiment of this invention is attached. It is explanatory drawing which showed the system configuration example of the steam steam power generation apparatus in the waste power generation system which concerns on embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a main part of a waste power generation system according to an embodiment of the present invention. The waste power generation system 1 includes a boiler 10 and a steam turbine power generation device 2 driven by steam from the boiler 10. The boiler 10 is heated by the waste heat of a waste incinerator (not shown) and generates steam at a temperature (less than 300 ° C.) that does not cause high-temperature corrosion. The steam turbine power generation device 2 includes a steam turbine 2A driven by steam from the boiler 10 and a generator 2B driven by the steam turbine 2A.

The steam turbine 2A includes a high-pressure turbine 11 and a medium-low-pressure turbine 12, and the generator 2B is coaxially connected to these. The boiler 10 and the inlet of the high-pressure turbine 11 are connected by a steam path S1 having no superheater, and the outlet of the high-pressure turbine 11 and the inlet of the medium-low pressure turbine 12 are connected to the steam path S2 via the dehumidifier 13. It is connected with. Further, the outlet of the medium-low pressure turbine 12 is connected to the condenser 14, and the water supply path W1 from the condenser 14 is connected to the boiler 10. Then, the steam path S3 extracted from the medium-low pressure turbine 12 is connected to the feed water heater 15 provided in the feed water supply path.

In the steam turbine power generation device 2 of such a waste power generation system 1, steam at a temperature that does not cause high temperature corrosion is supplied from the boiler 10 to the high pressure turbine 11, and the exhaust of the high pressure turbine 11 is supplied to the medium and low pressure turbine 12, and the medium and low pressure turbines. The exhaust of 12 is restored by the condenser 14, and is supplied to the boiler 10 via the water supply path W1. Here, the exhaust of the high-pressure turbine 11 is dehumidified via the dehumidifier 13 to become saturated steam having a high degree of dryness and an increased specific enthalpy, and is supplied to the medium- and low-pressure turbine 12. Further, the water returning to the boiler 10 via the water supply path W1 is heated by the feed water heater 15 to which the steam extracted from the medium-low pressure turbine 12 is supplied.

According to such a waste power generation system 1, since the steam from the boiler 10 is supplied to the high-pressure turbine 11 without overheating, it is possible to avoid high-temperature corrosion of the boiler 10 due to chlorine content in the waste, which has been a problem in the past. it can. As a result, it is not necessary to replace the boiler water pipe or the like for a long period of time, and safe and secure operation can be performed for a long period of time while suppressing maintenance costs. Further, by eliminating the risk of high temperature corrosion, it is not necessary to use an expensive corrosion-resistant material for each part of the boiler, and the initial equipment cost can be suppressed.

Further, since the boiler 10 is not provided with a superheater, the structure of the boiler 10 is simplified, and the boiler 10 can be easily manufactured and assembled. Further, since the thermal transmission rate of the boiler main body is generally higher than that of the superheater, the heat transfer area of the boiler 10 can be reduced by eliminating the superheater if the amount of heat exchanged is the same. Therefore, the structure of the entire boiler 10 becomes simple and compact.

Then, the exhaust of the high-pressure turbine 11 is dehumidified by the dehumidifier 13, so that the specific enthalpy is increased and supplied to the medium-low pressure turbine 12, and the exhaust of the medium-low pressure turbine 12 is restored to the boiler 10 in the feed water path W1. Since the feed water heater 15 that is overheated by the extraction air of the medium-low pressure turbine 12 is provided, a steam turbine cycle with high thermal efficiency can be realized, and the efficiency of the waste power generation system 1 can be improved.

FIG. 2 shows an example of a cleaning plant provided with a waste power generation system according to an embodiment of the present invention. The waste incinerator 20 into which the waste Re is charged includes a stoker furnace 21 to which the primary air is supplied, a primary combustion furnace to which the combustion gas is supplied, a secondary combustion furnace 23 to which the secondary air is supplied, and the like. A boiler 10 is installed next to the waste incinerator 20. The boiler 10 includes an economizer (ECO) 10A that preheats water supply by using the residual heat of the boiler main body 10P, the exhaust gas of the waste incinerator 20, and a drum 10B, and the water supply preheated by the economizer 10A incinerates waste. It is sent to the drum 10B heated by the waste heat of the furnace 20, and the drum 10B generates steam to be supplied to the high-pressure turbine 11. The steam generated here is steam that is suppressed to a temperature of less than 300 ° C. and has no risk of high temperature corrosion.

The exhaust gas from the waste incinerator 20 that has passed through the boiler 10 (economizer 10A) is attracted by the attracting ventilator 26 and dissipated from the exhaust stack 27, but Na-based chemicals are introduced before reaching the attracting ventilator 26. Fly ash is removed by passing through the bag filter 24, and NOx is removed by passing through the NOx reduction catalyst 25.

FIG. 3 shows a system configuration example of the steam turbine power generation device according to the embodiment of the present invention. The same reference numerals are given to parts that overlap with the above description, and duplicate description will be omitted. In FIG. 3, the solid line is the steam distribution line, and the dashed line is the water distribution line. A pressure control valve V1 or a normally closed valve V2 is appropriately provided in the steam flow line, and a level control valve V3 is appropriately provided in the water flow line.

In the illustrated example, the steam generated in the boiler 10 is supplied to the inlet of the high-pressure turbine 11 via the pressure control valve V1 and the speed control valve Vs. Further, a part of the steam from the boiler 10 is used as a heat source for steam reheating and is supplied to the reheater 16 described later.

A part of the steam exhausted from the outlet of the high-pressure turbine 11 is used as the heating steam for the dehumidifier 17 of the process P and the heat in the facility, and the remaining steam is guided to the dehumidifier 13. The drain generated in the dehumidifier 13 is guided to the dehumidifier 17.

Here, the operating pressure of the boiler (natural circulation type waste heat boiler with economizer) 10 is, for example, saturated steam of 5.4 MPa · g, and the temperature thereof is about 270 ° C. where there is no risk of high temperature corrosion. No superheater is provided in the boiler 10. The exhaust of the high-pressure turbine 11 becomes saturated steam having a pressure of 0.9 MPa · g, a temperature of 180 ° C., and a dryness of about 88%, but it dries by using the heat of some steam and dehumidifying with the dehumidifier 13. It becomes saturated steam with a degree of 99% or more.

Then, the dry saturated steam at the outlet of the dehumidifier 13 is further guided to the reheater 16 to become superheated steam having a pressure of 0.8 MPa · g and a temperature of about 220 ° C., and the medium-low pressure turbine 12 via the speed governor Vs. It is supplied to the entrance of. As described above, the heat source of the reheater 16 utilizes the steam generated by the boiler 10. The drain water after heating of the reheater 16 is flushed by sending it to the flash tank 18 for the reheater, the flash steam is collected at the inlet of the reheater 16, and the remaining drain water is passed through the level control valve V3. Is sent to the deaerator 17.

The steam supplied to the medium-low pressure turbine 12 is extracted in the middle stage of the medium-low pressure turbine 12 and sent to the feed water heater 15 via the pressure control valve V1 to heat the boiler feed water. The residual steam supplied to the medium- and low-pressure turbine 12 is exhausted from the outlet of the medium- and low-pressure turbine 12, and all of it is guided to the air-cooled condenser 14, condensed and stored in the tank 14A as condensate. The exhaust of the medium-low pressure turbine 12 is, for example, saturated steam having an exhaust pressure of about 10.1 kPa · a and a temperature of about 46 ° C. at an outside air temperature of 20 ° C., and saturated steam having an outside air temperature of about 18.8 kPa · a and a temperature of about 58 ° C. It becomes.

The steam extracted by the medium-low pressure turbine 12 is sent to the flush tank 19 after passing through the feed water heater 15, the flush steam is restored and sent to the tank 14A, and the residual drain water in the flush tank 19 is leveled. It is sent to the tank 14A via the control valve V3.

The condensate stored in the tank 14 is once sent to the deaerator 17 through the water supply path W1 by the condensate pump 28, and is supplied from the deaerator 17 to the boiler 10 through the water supply path W2 by the water supply pump 29. (A level control valve V3 is provided in the water supply paths W1 and W2 as needed).

In such a steam turbine power generation device 2, in the steam cycle for driving the steam turbine 2A, the heat drop between the inlet of the high pressure turbine 11 and the outlet of the medium and low pressure turbine 12 is a high temperature and high pressure system using a superheater. However, since the outlet enthalpy of the boiler 10 is lower than that of the high-temperature and high-pressure system, the amount of steam generated by the boiler 10 increases. Further, the above-mentioned heat drop is covered by the enthalpy increased by the adoption of the dehumidifier 13 and the reheater 16, and the outlet enthalpy of the medium-low pressure turbine 12 is lower than that of the high-temperature and high-pressure system. This makes it possible to substantially improve the power generation end efficiency as compared with the high temperature and high pressure method. In the configuration example shown in FIG. 3, the specific volume (m ³ / kg) of the inlet steam of the high-pressure turbine 11 can be made smaller than that of the high-temperature and high-pressure system, so that the turbine can be made highly efficient. Can be miniaturized.

As described above, the waste power generation system 1 according to the embodiment of the present invention can be made highly efficient without making the steam generated by the boiler 10 high temperature and high pressure. As a result, the efficiency of the waste power generation system 1 can be improved while eliminating the risk of high-temperature corrosion of the boiler 10. Therefore, it is not necessary to use an expensive corrosion-resistant material for the boiler parts, and it is possible to continuously operate the waste power generation system with high efficiency and stability while suppressing the initial cost and the maintenance cost.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and the design changes, etc. within the range not deviating from the gist of the present invention, etc. Even if there is, it is included in the present invention. Further, each of the above-described embodiments can be combined by diverting the technologies of each other as long as there is no particular contradiction or problem in the purpose and configuration thereof.

1: Garbage power generation system, 2: Steam turbine power generation equipment,
2A: Steam turbine, 2B: Generator,
10: Boiler, 10A: Economizer, 10B: Drum,
11: High pressure turbine, 12: Medium and low pressure turbine, 13: Dehumidifier,
14: Condenser, 15: Feed water heater, 16: Reheater, 17: Deaerator,
18: Flash tank for reheater, 19: Flash tank,
20: Waste incinerator, 21: Stalker furnace, 22: Primary combustion furnace, 23: Secondary combustion furnace,
24: Bag filter, 25: NOx reduction catalyst, 26: Ventilator,
27: Exhaust pipe, 28: Condensate pump, 29: Water supply pump,
S1, S2, S3: steam path, W1, W2: water supply path,
V1: Pressure control valve, V2: Always closed valve, V3: Level control valve, Vs: Speed control valve

Claims (4)

It is equipped with a boiler that is heated by the waste heat of waste incineration and a steam turbine power generator driven by steam from the boiler.
The steam turbine power generator
The high-pressure turbine to which steam of about 270 ° C. or lower , which is a temperature at which high-temperature corrosion does not occur, is supplied from the boiler, the medium-low-pressure turbine to which the exhaust of the high-pressure turbine is supplied, and the exhaust of the medium-low-pressure turbine are condensed. Equipped with a water supply route to supply the boiler
The exhaust gas of the high pressure turbine is supplied to the medium and low pressure turbine via a dehumidifier.
A feed water heater for supplying steam extracted from the medium-low pressure turbine is provided in the feed water supply path.
The boiler is not provided with a superheater, and the boiler and the inlet of the high-pressure turbine are connected by a steam path having no superheater.
A waste power generation system characterized in that a part of steam from the boiler is used as a heat source for reheating the exhaust gas of the high-pressure turbine. Steam through the pre-Symbol dehumidifier claims steam from the steam path is reheated by the reheater which is supplied located outside of the boiler, characterized in that it is supplied in said low pressure turbine Item 1 The waste power generation system. The waste power generation system according to claim 1 or 2, wherein the generator of the steam turbine power generation device is installed at the same time as the high-pressure turbine and the medium-low pressure turbine. The waste power generation system according to any one of claims 1 to 3, wherein a part of the exhaust gas of the high-pressure turbine is used for heating a deaerator provided in the water supply path.

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