JP2003097224A - Power generating unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal power generating unit wherein an efficiency of power generation is improved by generating electric power by use of a water channel having a drop in a water circulating line of condensed water. SOLUTION: Steam discharged from a steam turbine of a steam turbine generator is made to flow to a condenser, condensed water is produced by cooling it with cooling water, condensed water is pressurized in this condensed water circulating channel and is circulated to a deaerator 56 which is provided at a relatively high place, a plurality of falling water pipe 56 and 57 are connected to a falling channel after deaerated condensed water is temporarily stored in a storage tank 65, and micro hydraulic turbine generators 1 to 3 are installed in this each water falling pipe 66 and 67 via an inlet valve 4 and a guide vane 5 whereby power generation by water power is made. A by-pass pipe 10 is provided in parallel and a by-pass valve 11 is connected to this by- pass pipe 10 so that repairs can be made at the time of failure of the micro hydraulic turbine generators 1 to 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal power generation system with improved power generation efficiency.

[0002]

2. Description of the Related Art A thermal power generator 41 rotates a steam turbine 42 with high-pressure steam and transmits the rotation of the steam turbine 42 to a generator 43 to generate electric power. At this time, the steam discharged from the steam turbine 42 is heat-exchanged with a large amount of cooling water (sea water) in the condenser 44 to generate condensed water, and this condensed water is turned into high-pressure water to generate steam to generate steam. A condensate circulation flow channel 45 is formed so as to rotate 42.

A conventional condensate circulation flow channel 45 is constructed as shown in FIG. The steam turbine generator 46 is provided with a high-pressure steam turbine 47, a low-pressure steam turbine 48, a generator 43, etc. connected to the same rotating shaft. The condenser 44 causes heat exchange between the exhaust steam from the low-pressure steam turbine 48 and cooling water such as seawater. The exhaust steam that has undergone heat exchange is cooled, becomes condensed condensed water, and flows into the condensed water pump 50.

The condensate pump 50 extracts the condensed condensed water, pressurizes it, and causes it to flow back to the condensate demineralizer 51. The condensate demineralizer 51 controls the impurities mixed in the condensate, the condenser 44.
And metal oxides such as iron and copper, which are corrosion products in the system, salt of seawater, and dust, are removed, and the booster pump 52 for pressurization is made to flow. A booster pump 52 for increasing pressure as a water absorption pump to the deaerator raises the pressure of the desalted condensate and injects it into the first and second low pressure heating devices 54 and 55 via the water level adjusting valve 53.

First and second low pressure heating devices 54, 55
Extracts a part of the low-pressure steam from the low-pressure steam turbine 48 and extracts it as a heat source to heat the condensate and inject it into the deaerator 56. The deaerator 56 performs vacuum deaeration of the non-condensable gas from the heated condensate to separate and remove the non-condensable gas such as oxygen and carbon dioxide gas in the condensate, thereby electrically and chemically operating the boiler and auxiliary equipment. Avoid corrosion. The degassed condensate is sent to a boiler feed water pump 58, for example, a boiler feed water pump, via an inlet valve 57. Boiler feed pump 58
Pressurizes the condensate into high-pressure condensate and sends it to the first and second high-pressure heating devices 59 and 60.

First and second high pressure heating devices 59, 60
Is a part of the high-pressure steam discharged by the high-pressure steam turbine 47, and heats the condensate as a heat source to make high-temperature high-pressure condensate.
It flows into the boiler 61. The boiler 61 generates high-pressure steam from the high-temperature and high-pressure condensate, sends the high-pressure steam to the high-pressure steam turbine 47, and rotates it. By circulating the condensate in this way, a large amount of condensate is effectively reused to generate power by effectively using resources.

The inventor of the present invention is carrying out development for the purpose of further improving power generation efficiency. A water level difference is formed in the condensate circulation flow path 45 of the thermal power generation device 41 described above. FIG. 4 shows a relative approximate height difference. For example, if the installation floor of the steam turbine generator 46 is the fifth floor, this height difference is that the condensate demineralizer 51 is installed on the first floor,
The deaerator 61 is on the 5th floor, the inlet valve 57 and the boiler feedwater pump 58 are on the 1st floor, and the boiler 61 is at the uppermost position, which is the 6th floor and above.

The falling flow path in the condensate circulation flow path 45 includes a flow path from the condenser 44 to the condensate demineralizer 51 and a deaerator 56.
To the inlet valve 57 and the boiler feed water pump 58. The flow path from the latter deaerator 56 to the inlet valve 57 and the boiler feed water pump 58 is as shown in FIG. 5 more specifically.

The deaerator 56 temporarily stores the degassed condensate in a water storage tank 65. The water storage tank 65 is provided to stably supply condensate to the boiler feed water pump 58 and the like even when the load changes, and to stably supply high-pressure, high-temperature steam from the boiler 61 to the high-pressure steam turbine 47. is there. The capacity of the water storage tank 65 is, for example, large enough to circulate the total amount of water stored in one hour. The water tank 65 has a plurality of downcomers, for example, three downcomers 66, 67, 68.
Are connected.

The downcomer pipe 58 is a downcomer pipe for initial startup of thermal power generation, and the downcomer pipes 66 and 67 are downcomer pipes in a steady state of thermal power generation. An inlet valve 5 is attached to each downcomer 66, 67.
7, the inlet strainer 69, the boiler feed water pump 58, and the motor drive pump 70 are used to form flow paths in the first and second high-pressure heating devices 59 and 50.

[0011]

In the above-described thermal power generation device, a large amount of condensate flows through the downcomers 66, 67, 68. Therefore, by studying power generation also in this flow path, the thermal power generation device is further improved. We are considering improving the power generation efficiency.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a thermal power generation device with improved power generation efficiency by generating power also by using a water channel having a head of a condensate circulation system. To do.

[0013]

In order to achieve the above object, the present invention provides a thermal power generation device having the following structure, which also causes power generation in the condensate circulation flow path to realize effective recovery of energy.

That is, the thermal power generator according to claim 1 is a steam turbine that rotates by a steam generated in a boiler to rotate a generator, and a condenser that cools the steam discharged from the steam turbine to condense it. And a deaerator that removes non-condensed gas from the condensate from this condenser, a water storage tank installed at a relatively high place to store the condensed water degassed by this deaerator, and this storage water A water supply pump connected to the tank via a downcomer pipe to supply the condensate of the water storage tank to the boiler; and a micro water turbine generator arranged in the flow path of the downcomer pipe. To do.

According to the first aspect of the invention, since the micro-turbine generator is installed in the drop passage after degassing, the energy can be effectively recovered, and the power generation efficiency of the thermal power generator can be improved.

A thermal power generator according to a second aspect is the thermal power generator according to the first aspect, wherein the downcomer is provided with an initial start up downcomer and a steady state downcomer in parallel. The pipe is provided with a micro-turbine generator having a relatively small generated power, and the steady-state precipitation pipe is provided with a micro-turbine generator having a relatively large generated power.

According to the second aspect of the present invention, the micro-turbine generator adapted to the amount of flowing water is used without wasting the condensate flowing from the start of thermal power generation with a relatively small flow rate to the steady-state thermal power generation. Can generate power efficiently.

A thermal power generator according to a third aspect is the thermal power generator according to the first aspect, wherein the downcomer is provided with a downcomer having a relatively small water flow rate and a downcomer having a relatively high water flow rate. A down stream pipe with a small water flow rate is provided with a micro water turbine generator with a relatively small generated power, and a down stream tube with a relatively high water flow rate is provided with a micro water turbine generator with a relatively large generated power. To do.

According to the invention of claim 3, since the micro-turbine generator adapted to the precipitation flow rate is connected, the power generation efficiency is improved.

The thermal power generation device of claim 4 is the same as that of claim 1,
Alternatively, in the thermal power generation device according to 3, the bypass flow path is provided in parallel with the flow path to the micro water turbine generator provided in the downcomer pipe, and the bypass flow path can selectively flow condensate. Is characterized by.

According to the invention of claim 4, since the bypass flow passage for selectively flowing the condensate is provided in parallel with the flow passage to the micro water turbine generator, even if the micro water turbine generator fails, for example. By simply stopping the flow of water to the micro turbine generator, it is possible to repair the failed micro turbine generator while continuing the thermal power generation without stopping the power generation of the thermal power generator.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of a thermal power generator of the present invention will be described with reference to FIGS. Descriptions of the same parts as those in FIGS. 4 and 5 are duplicated, and thus the same reference numerals are given and the description thereof is omitted.

In this embodiment, in the thermal power plant 41 described with reference to FIG. 4, the deaerator 56 and the condensate falling flow path from the water storage tank 65 are formed by downcomers 66 to 68, and the downcomers 56 to 68 are formed. In this case, a hydroelectric generator is installed at 58 to generate power with improved power generation efficiency. The hydraulic power generator is a small-sized hydraulic power generator, and the generated power is, for example, 5 kw to 100
It is a kw class micro turbine generator.

In the downcomer pipe 66, in the initial power generation period of the thermal power plant 1, a micro water turbine generator 1 is installed which can generate power with a pipe diameter that allows a relatively small amount of condensed water and a relatively small amount of water. The magnitude of the generated power is, for example, about 30 kW.

The downcomer pipes 67 and 68 are provided for flowing a relatively large amount of condensate flowing out of the water storage tank 65 during the steady-state power generation period of the thermal power generation system 41. In this embodiment, two downcomer pipes 67 and 68 are additionally installed. The diameters of the downcomers 67 and 68 are larger than the diameter of the downcomer 66. Micro water turbine generators 2 and 3 having a water flow rate suitable for the flow rate are installed in the downcomer pipes 67 and 68, respectively. The amount of electric power generated by each of the micro turbine generators 2 and 3 is, for example, about 50 kW.

Micro water turbine generators 1 to 3 are provided in the condensate inflow paths of the micro water turbine generators 1 to 3 of the downcomer pipes 66 to 68, respectively.
An inlet valve 4 driven by a motor is provided for use when it is desired to prevent the inflow of condensate into the. A guide vane 5 is installed between each inlet valve 4 and each micro turbine generator 1 to 3. The guide vane 5 is installed to automatically adjust the amount of condensed water supplied to each of the micro turbine generators 1 to 3. The automatic control of the guide vanes 5 is controlled as the thermal power generation device 41 by the control device of the boiler feed water pump or the automatic process control device, and the control as the micro water turbine generators 1 to 3 is not executed.

Further, a turbine check valve 6 is installed in the condensate outflow passage of each of the micro turbine generators 1 to 3. The water turbine check valve 6 is for blocking the reverse flow of the condensed water to each of the micro water turbine generators 1 to 3. That is, the water turbine check valve 6 is installed to control the inlet valve 4 in a non-open state and prevent backflow to each of the micro water turbine generators 1 to 3 when condensate is flowing to the bypass pipe 10. There is. In this way, the hydroelectric power generation device 7 is installed in the condensate falling flow path. Micro hydroelectric generators 1-3 connected to each downcomer 66-68,
Multiple machines may be connected in series. In this case, the generated power of the downstream micro hydraulic power generator is small.

This hydroelectric generator 7 requires regular maintenance and may be out of order. In such a case, it is important not only to stop the power generation operation of the thermal power generation device 41 but also to improve the power generation efficiency and to stably supply the power.

As a countermeasure against this, a bypass passage, for example, a bypass pipe 10 is connected in parallel to each hydraulic power generation device 7. A bypass valve 11 driven by a motor is connected to each bypass pipe 10. The diameter of the bypass pipe 10 is the same as or nearly the same as the combined diameter of the downcomers 66 to 68. That is, the water flow rate of the bypass pipe 10 is the same or almost the same as the total water flow rate of the downcomer pipes 66 to 68.

By installing the respective bypass pipes 10 in this way, when maintenance or an unexpected accident occurs, the bypass valve 11 is automatically operated by the motor to be loosened and controlled to the open state. . After confirming that the bypass valve 11 is completely opened, the inlet valves 4 of the hydraulic power generator 7 are automatically operated by the motor to be closed and controlled to be in the non-open state. As a result, the inflow of condensate into the micro turbine generators 1 to 3 is stopped, and after confirming the stop of this inflow, maintenance and accident recovery work are performed. In this way, the thermal power generation device 41 having the hydraulic power generation function is configured.

Next, the micro turbine generators 1 to 3 will be described with reference to FIG.

The micro turbine generators 1 to 3 are composed of a turbine section 15 in which a condensate flow flows and a rotating impeller rotates, and a generator section 16 in which the rotational movement of the rotating impeller is transmitted to generate electric power. The water turbine portion 15 is provided with a cylindrical outer cylinder 17 in which a condensate flow channel is formed, and in the outer cylinder 17, a rotary impeller 18 that rotates by the flow of condensed water is provided. A pulley 20 is fixed to the end of the rotary shaft 19 of the rotary shaft 19 on the inflow side of the condensate flow. The turbine part 15 is a cylindrical outer cylinder 17
The rotary impeller 18 is configured to rotate by the condensate flow flowing inside. The shape of the outer cylinder 17 is cylindrical, and is formed so that the diameter of the rotary impeller 18 is small and the diameter thereof is enlarged on the outflow side.

The generator unit 16 is rotated by the rotation of the rotary impeller 18 being transmitted to generate electricity. A pulley 22 is fixed to the end of the rotary shaft 21 of the generator unit 16. A belt 23 is hung on the pulleys 20 and 22, and the rotation of the rotary impeller 18 is transmitted to the generator unit 16.

Next, the power generation operation of the thermal power generator 41 will be described. Each bypass valve 11 in FIG. 1 is controlled to a non-open state,
The inlet valve 4C of the initial startup downcomer 66 is controlled to be in the open state, and the inlet valves 4A and 4B are controlled to be in the non-open state. In this state, the thermal power generation operation is started. The high-pressure steam turbine 47 of the thermal power plant 41 shown in FIG. 4 rotates at high speed when high-pressure steam is pumped from the boiler 61. High pressure steam turbine 47
The steam discharged from the low pressure steam turbine 48 is supplied to the low pressure steam turbine 48 to rotate the low pressure steam turbine 48 at a high speed. The steam discharged from the low-pressure steam turbine 48 is cooled by the condenser 44 to generate condensed water.

Condensate is condensed by a condensate pump 50 and a condensate demineralizer 51.
The pressure is boosted by the booster pump 52 via the and to the deaerator 56 at the height of the fifth floor. Booster pump 5
2 is a pump for supplying condensate water to the deaerator 56.
The condensed water degassed by the deaerator 56 is stored in the water storage tank 65. The stored condensate drops in a relatively small amount during the initial period from the downcomer 66 having a small diameter. This fall is the drop from the 5th floor to the 1st floor. A micro water turbine generator 1 is provided in this drop flow path to generate power corresponding to the flow rate.

The micro turbine generators 2 and 3 for driving the steam turbine have a boiler feed pump 58 for driving the steam turbine.
When the boiler water supply pump 58 is in-service, the circuit breakers 32 and 33 for the micro water turbine generator are turned on, and the output of the generated power is started.

Condensate discharged from the micro turbine generator 1 is
The boiler water supply pumps 58A and 70A raise the pressure to a high pressure, and the water is sent to the boiler 61 on the sixth floor via the first and second high pressure heating devices 59 and 60. The boiler 61 heats the high-pressure high-temperature condensate to generate high-pressure steam. When the generated high-pressure steam is supplied to the high-pressure steam turbine 47, the high-pressure steam turbine 4
7 rotates at high speed to generate electricity. By repeating such a cycle, the amount of condensate gradually increases. This sequential increase in the amount of condensate controls the inlet valve 4A sequentially to the fully open state. When the thermal power generation is in a steady state, the inlet valves 4B and 4C are also sequentially controlled to the fully open state.

In steady-state thermal power generation, the amount of condensate increases, the amount of water that falls from the deaerator 56 and the water storage tank 65 increases, and the amount of water that falls from the downcomers 66 to 68 increases. The flow rate of the condensate flows to the micro turbine generators 1 to 3 to generate hydroelectric power. When the steam turbine generator 46 generates 700 mw, the steam flow needs 2000 tons per hour. Therefore, the flow rate of water flowing through the deaerator 56 and the downcomers 66 to 68 is 20 per hour.
It is 00 tons. The deaerator 56 is installed on the 4th floor to 5th.
When installed on the first floor, the drop between the inlet strainer 69, the boiler feed pump 58 installed on the first floor, and the water storage tank 65 installed on the fifth floor is about 20 m. When the micro turbine generators 1 to 3 are installed in the drop flow path of this head, the micro turbine generator 1 with a flow rate of 2000 tons per hour and a head of 20 m
The generated power p of 3 to 3 is p = 9.8 × 2000/3600 × 20 = 109 kw, and the pressure loss of the piping system, the micro turbine generator 1 to
Considering the power generation efficiency of 3, it is possible to install the micro turbine generators 1 to 3 of 100 kw class.

The electric power generated by the micro turbine generator 1 is used as electric power for driving a motor such as a pump in the condensate circulation path 45, for example. Other micro turbine generator 2,
The generated electric power of No. 3 is used as electric power for the boiler 61 in the condensate circulation route, for example.

In the thermal power plant 41, two boiler feed pumps 58B and 58C for driving a steam turbine and one boiler feed pump 58A for driving a motor are installed. This one boiler feed pump for driving the motor is operated from the time of ignition of the boiler 61 to a unit start up to a load of about 25% and from the load of 25% or less to extinguishing the boiler 61. In the operation load zone in the steady state, two steam turbine drive boiler feed pumps 58 are operated. The distribution of the feed water flow rate at 100% load is the same for the two boiler feed water pumps for driving the steam turbine. Therefore, three micro turbine generators 1-3
The output power of the micro turbine generator 1 is about 30 kW, and the output of the micro turbine generators 2 and 3 is about 50 kW.

(Operation (Activation) of Micro Hydro Turbine Generator) After the boiler water supply pump 58 is activated, the operation of the motor driven micro hydro turbine generator 1 is started. During high-pressure cleanup and boiler cleanup, the inlet valves 4 of the micro-turbine generators 1 to 3 are controlled to be fully opened, and the micro-turbine generator 1 is idled under no load. Before the boiler 61 is ignited, the motor feed micro turbine generator 1 drive breaker 20 is turned on in accordance with the activation of the boiler feed pump 58,
Start output.

This electric power is supplied to the motors of the thermal power generator 41,
It can be used for pumps, heating devices, lighting, etc.

As described above, by installing the micro turbine generator in the water channel having the head of the condensate circulation flow path of the steam discharged during thermal power generation, the power generation efficiency of the thermal power generator can be improved.

Next, a case where the micro turbine generators 1 to 3 are maintained or broken down will be described. The thermal power generation operation can be performed for maintenance and repair without stopping. By-pass valve 11 of bypass pipe 10 of micro-turbine generators 1 to 3 that has been maintained or failed
Are controlled to the fully open state. After the bypass valve 11 is fully opened, it controls the inlet valve 4 connected to the inflow passage of the micro hydraulic turbine generator so that it is not opened. After that, the inflow of condensed water is stopped in the micro turbine generators 1 to 3,
After confirming this stop, maintenance or repair of the failure is executed.

After the maintenance and the repair of the trouble are completed, the inlet valve 4 is controlled to the fully opened state relatively slowly. After confirming that the inlet valve 4 is fully opened, the bypass valve 11 of the bypass pipe 10 is controlled to be closed. As a result, all the condensate flowing in the downcomers 66 to 68 can be made to flow to the micro water turbine generators 1 to 3. In this way, the maintenance and repair of the failure are completed.

The electric circuit of such a thermal power plant is as shown in FIG. The power generation output circuit of the thermal power generator is connected to the bus 25 of the main circuit (internal m / c bus). This bus 2
The AC voltage generated at 5 is, for example, 3 kv to 6 kv. This bus 25 and the bus 26 of the primary circuit (internal p
/ C busbar) circuit breaker 27, transformer 28, circuit breaker 2
Nine serial connection circuits are connected. On the bus 25, the output circuits of the micro-turbine generators 1 to 3 are respectively provided with circuit breakers 31,
They are connected via 32 and 33. The AC voltage generated on this bus bar 26 is, for example, 460v. A load circuit 34 such as a motor of a power plant is connected to each of the bus bars 26 via a circuit breaker 33.

Each micro-turbine generator 1 to 3 has a voltage output 4
The rated voltage is 60 v, and the voltage is output to the bus bar 26 through the breakers 31 to 33 for the micro hydraulic turbine generators 1 to 3.

(Stop, interlock operation) The stop operation of the micro turbine generators 2 and 3 is performed by the micro turbine generator 2,
3. Before out-service of the boiler feed water pump 58 for driving the boiler, the circuit breakers 32 and 33 are controlled to be in the non-conducting state and disconnected from the bus bar 26, and when the boiler feed water pump 58 is stopped, the micro turbine generator 2, Stop 3.

The stop condition of the motor-driven micro water turbine generator 1 is that the circuit breaker 31 is controlled to be in the non-conducting state before the boiler 61 is extinguished to disconnect from the bus bar 26, and the motor-driven boiler feed water pump 58 is stopped. At the same time, the micro turbine generator 1 is stopped. Further, when the boiler water supply pump 58 is stopped during the operation in the steady state, the interlocking interlock is provided to stop the micro turbine generator 1 and control the bypass valve 11A to the open state.

The electrical protection circuit has a minimum interlock circuit when an overload or a short circuit occurs. When an abnormality such as a power failure or a bus protection operation occurs on the bus bar 26, the bus bar 26 side circuit breakers 31 to 33 are controlled to be in a non-conductive state,
The micro-turbine generators 1 to 3 control the guide vanes 5 to be fully opened, and after a short-time no-load operation, the bypass valve 11 is fully opened, and the inlet valve 4 of the micro-turbine generator is controlled to a non-open state.

(Operation of guide vanes) Guide vanes 5 for controlling the amount of water flowing into each of the micro turbine generators 1 to 3.
Receives an opening command from the boiler water supply pump control device or the boiler automatic control device to control the inflow water amount. The discharge pressure of the boiler feed water pump 58 and the flow rate of the condensate water are controlled by the rotational speed of the pump. The guide vane 5 is controlled to open and close in proportion to the control command of the rotation speed of the boiler feed water pump 58, and the load control corresponding to the flow rate of the condensate becomes possible.

[0052]

According to the present invention, hydroelectric power generation can be performed by utilizing a water channel having a head of a condensate circulation system, and a thermal power generation device with improved power generation efficiency can be obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a drop passage for explaining an embodiment of a thermal power generation device of the present invention.

FIG. 2 is a diagram for explaining an embodiment of the micro water turbine generator shown in FIG.

FIG. 3 is an electrical circuit connection diagram for specifically explaining an electrical circuit of the thermal power generation system in FIG.

FIG. 4 is a water channel diagram for explaining a condensate circulation flow channel of a conventional thermal power generation device.

5 is an electric circuit connection diagram for specifically explaining an electric circuit of the thermal power generation system in FIG.

[Explanation of symbols]

1-3 ... Micro water turbine generator, 4 ... Inlet valve, 5 ... Guide vane, 6 ... Water turbine check valve, 7 ... Hydroelectric power generation device, 10 ... Bypass pipe, 11 ... Bypass valve, 15 ... Water turbine section, 16 ... Power generation Machine part, 17 ... Outer cylinder, 18 ... Rotating impeller, 19, 21 ... Rotating shaft, 20, 22 ... Pulley, 23 ... Belt, 25, 26
... Bus, 27-29, 31-33 ... Circuit breaker.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F03B 17/06 F03B 17/06 F22D 11/00 F22D 11/00 C

Claims (4)

[Claims] 1. A steam turbine that rotates a generator by being rotated by steam generated in a boiler, a condenser that cools the steam discharged from the steam turbine to condense it, and a condenser from this condenser. A deaerator for removing non-condensed gas from water, a water tank installed at a relatively high place for storing condensate deaerated by the deaerator, and a water tank connected to this water tank via a downcomer pipe. A thermal power generation device comprising: a water supply pump that supplies the condensate of the water storage tank to the boiler; and a micro-turbine generator disposed in the flow path of the downcomer pipe. 2. The downcomer is provided with an initial start up downcomer and a steady state downcomer in parallel, and the initial start up downcomer is provided with a micro-turbine generator of relatively small generated power. The thermal power generator according to claim 1, wherein the downcomer pipe for steady state is provided with a micro-turbine generator of relatively large generated power. 3. The downcomer is provided with a relatively low water flow downcomer and a relatively high water flow downcomer, and the relatively low water flow downcomer has a relatively small amount of power generated by a micro turbine generator. 2. The thermal power plant according to claim 1, wherein a water turbine generator is provided, and a micro turbine generator having a relatively large generated power is provided in the downcomer pipe having a relatively large water flow rate. 4. A bypass flow path is provided in parallel with the flow path to the micro water turbine generator provided in the downcomer pipe, and the bypass flow path can selectively flow condensate. The thermal power generation device according to claim 1, 2 or 3.