JP2003090508A - Water feed system and operation method of steam power generating plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the water feed system and the operation method of a steam power generating plant capable of relaxing a load limit during maintenance and inspection of a feed water heater. SOLUTION: When operation isolating the feed water heater is effected, a feed water heater bypass system bypassing one or more feed water heaters situated downstream from the isolated feed water heater is situated. During isolation operation of the feed water heater, water flows to the bypass system, a flow quantity of feed water passing the feed water heater bypassed by the bypass system is reduced. A flow of quantity of feed water passing the feed water heater bypassing through the bypass system is reduced, and a load limit is relaxed by effecting operation at a speed lower than the limit speeds of heating steam piping, the feed water heater, and the like.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a water supply system of a steam power plant and an operating method thereof.

[0002]

2. Description of the Related Art In a steam power plant, a condenser built-in type feed water heater is adopted in consideration of layout when a low-pressure turbine has a plurality of exhausts. In this case, the number of series of feed water heaters has a two-series configuration due to constraints such as steam turbine performance. Also, on the downstream side of the feed water heater of the two series configuration,
A second feed water heater is installed for the purpose of further heating the feed water that has passed through this feed water heater. This second feed water heater is configured as one series from the viewpoint of rationalized specifications. Further, a bypass system is installed in each of the two-system feed water heater and the one-system feed water heater.

Regarding the structure of the low-pressure feed water heater and the low-pressure feed water system, thermal power nuclear power generation Vol. 42, No. 1
1 (19/11/10) "Introductory Course / Heat Exchanger and Piping-
Valve "," Piping and valves used in VII thermal power plants (1) "
2 of FIG.

[0004]

In the water supply system of the conventional steam power plant constructed as described above, when performing maintenance inspection of the water supply heater of the two-series configuration, either one of the two systems is supplied. Is separated from the water supply system, and the other system of the two systems and the bypass system are used to supply water to the one (second) water heater installed downstream. There is.

However, when the above-mentioned operation is performed by the maintenance and inspection of the feed water heater, the heating steam supplied to the feed water heater of one series increases significantly due to the decrease of the inlet feed water temperature of the feed water heater. Therefore, it is necessary to limit the load in order to keep the flow velocity of the heating steam pipe, feed water heater, etc. below the limit. This causes a disadvantage of load limitation for a plant that performs continuous high load operation in base load operation such as a large-capacity coal-fired steam power plant.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a water supply system for a steam power generation plant, which can alleviate a load limitation during maintenance and inspection of a water supply heater, and the same. To provide a driving method.

[0007]

In order to achieve the above object, a water supply system of a steam turbine power plant of the present invention is installed at a first water supply heater and a downstream side of the first water supply heater. A second feed water heater, a bypass system bypassing the second feed water heater, and the second system installed in the bypass system
And a bypass valve for controlling the flow rate of feed water that bypasses the feed water heater.

Further, the method of operating the water supply system of the steam power generation plant of the present invention comprises a first low-pressure feed water heater and a second low-pressure feed water heater installed downstream of the first low-pressure feed water heater. And a bypass system that bypasses the second low-pressure feed water heater, and a bypass valve that is installed in the bypass system and that controls the flow rate of feed water that bypasses the second low-pressure feed water heater. In the method for operating a water supply system, during the isolated operation of the first water heater, the opening degree of the bypass valve is controlled to bypass the water supplied to the second low-pressure water heater. It is a thing.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 shows a schematic configuration example of a low-pressure feed water heater and a low-pressure feed water system of a general steam power plant.

Exhaust gas from the steam turbine 1 is condensed in the condenser 3 to be condensed water, and the low-pressure feed water leaving the condensate pump 4 is heated by passing through the low-pressure feed water heaters 5A, 5B and the downstream low-pressure feed water heater 6. And is supplied to a downstream feed water heater (for example, a deaerator) as needed. The low-pressure feed water heater 5A is provided with a feed-water inlet valve 7A and a feed-water outlet valve 8A so that the low-pressure feed water system 9A and the low-pressure feed water heater 5A can be isolated from each other. Further, heating steam is supplied from the steam system 13 as a heating source of the low-pressure feed water heater, and the steam system 13 and the feed water heater 5A can be isolated by the steam inlet valve 12A. Here, the low-pressure feed water heaters 5A and 5B represent one or more feed-water heater groups, and when there are a plurality of low-pressure turbine exhausts, a condenser-incorporated feed water heater is adopted because of layout considerations. In this case, the number of feed water heaters is set to two due to restrictions such as steam turbine performance. A low pressure feed water heater bypass system 11 and a low pressure feed water heater bypass valve 10 are provided in order to secure a feed water flow rate during maintenance and inspection of the low pressure feed water heaters 5A and 5B.

The low-pressure feed water heater 6 is a low-pressure feed water heater 5A,
Installed for the purpose of further heating the water supply that has passed 5B,
From the viewpoint of rationalization of specifications, the system is configured as a single system, and a low pressure feed water heater bypass system 20 and a low pressure feed water heater bypass valve 19 are installed in consideration of maintenance and inspection of the low pressure feed water heater 6.

In such a water supply system configuration, at the time of maintenance and inspection of the low pressure water supply heater 5A, the low pressure water supply heater 5A is isolated from the water supply system 9A and the low pressure water supply from the condensate pump 4 is separated as described above. After passing through the low-pressure feed water heater 5B and the low-pressure feed water heater bypass system 11, the low-pressure feed water heater 6 is supplied to the downstream feed water heater (for example, a deaerator) as needed. At this time, the heating steam of the low-pressure feed water heater 6 increases due to a decrease in the inlet feed water temperature of the low-pressure feed water heater 6, and a load limit of about 90% load is applied in order to keep the flow velocity below the limit flow velocity of the heating steam pipe, feed water heater, etc. Is required.

Further, in a recent steam power generation plant, as shown in FIG. 3, the low-pressure feed water heater 5 can be constructed as a single series due to the improvement of steam turbine performance and the like. However, in such a water supply system configuration, at the time of maintenance and inspection of the low-pressure water supply heater 5, the low-pressure water supply heater 5 is separated from the water supply system 9, and the low-pressure water supply exiting the condensate pump 4 is supplied to the low-pressure water supply heater bypass. It passes through the system 11, passes through the low-pressure feed water heater 6, and is supplied to a downstream-side feed water heater (for example, a deaerator) as needed, but the heating steam of the low-pressure feed water heater 6 is supplied to the low-pressure feed water heater. A drastic increase due to the decrease in the inlet feed water temperature of No. 6 requires a load limit of about 50% load in order to keep the flow velocity below the limit flow velocity of the heating steam pipe, feed water heater, etc. This causes a disadvantage of load limitation for a plant that performs continuous high load operation in base load operation, such as a large-capacity coal-fired steam power plant.

FIG. 1 shows a steam power plant which is an embodiment of the present invention. In the present embodiment shown in FIG. 1, a steam turbine 1 driven by steam supplied from a steam generator (not shown), a generator 2 connected via a shaft to a steam turbine 1, and a steam driving a steam turbine 1 Condenser for condensing water 3, Condensate pump for pressurizing condensate 4, Low-pressure feed water heater 5 for overheating pressurized condensate 5, Downstream low-pressure feed water heating installed downstream of low-pressure feed water heater 5. And a container 6. A heating steam system 13 is provided as a system for supplying heating steam to the low-pressure feed water heater 5, and the heating steam systems 13 and 18 are provided.
A heating steam inlet valve 12 for controlling the supply amount of the heating steam supplied to the low-pressure feed water heater 5 is installed in the above. Similarly, as a system for supplying heating steam to the downstream low-pressure feed water heater 6, a downstream heating steam system 18 having a downstream heating steam inlet valve 17 is installed.

Further, in the water supply system of the present embodiment, water supply is branched from the middle of the route for guiding the water supply from the condensate pump 4 to the low-pressure water supply heater 5 to bypass the water supply supplied to the low-pressure water supply heater 5. The heater bypass system 11 and the downstream feed water heating for branching the feed water heated by the low pressure feed water heater 5 to the low pressure feed water heater 6 to bypass the feed water supplied to the low pressure feed water heater 6. A bypass system 20 is installed. Further, the feed water heater bypass system 11 and the downstream side feed water heater bypass system 20 are provided with a feed water heater bypass valve 10 and a downstream side feed water heater bypass valve 19 for controlling feed water to be bypassed. A feed water heater inlet valve 7 is installed on the inlet side of the low pressure feed water heater 5, and a feed water heater outlet valve 8 is installed on the outlet side thereof. Similarly, a feed water heater inlet valve 14 is installed on the inlet side of the low pressure feed water heater 6, and a feed water heater outlet valve 15 is installed on the outlet side thereof. Also,
A bypass flow rate control device 30 is provided as a control device for controlling the feed water flow rate that bypasses the downstream side feed water heater 6, and the bypass flow rate control device 30 controls the valve opening degree of the downstream side feed water heater bypass valve 19. .

In the present embodiment configured as described above,
At the time of maintenance and inspection of the low-pressure feed water heater 5, the flow rate of water flowing through the low-pressure feed water heater bypass system 20 on the downstream side needs to be operated at a speed equal to or less than the limiting flow velocity of the heating steam pipe, the feed water heater, etc.
It is necessary to set the feedwater heater bypass flow rate ratio corresponding to the required turbine load.

In this case, setting of the feedwater heater bypass flow rate corresponding to the required plant load can be achieved by setting the valve opening of the feedwater heater bypass valve whose flow rate can be adjusted in advance. , Shows the case where this can be set from the control device.

FIG. 4 shows an example of feed water heater bypass flow rate setting corresponding to the turbine load. That is, when the turbine load is 50% or less, the low pressure feed water heater bypass system 2
When the turbine load is 100%, if the water flow rate of the downstream low-pressure feed water heater bypass system 20 and the water flow rate of the downstream low-pressure feed water heater 6 are equalized (feed water heater bypass Flow rate ratio = 1.0), and further reduce the feed water heater bypass flow rate ratio (operate below the restricted flow velocity of the heating steam pipe, feed water heater, etc.) to improve the thermal efficiency during bypass operation. Is shown as an example. Here, the feedwater heater bypass flow rate indicates the rate of the feedwater heater bypass flowrate and the feedwater heater passing feedwater flowrate.

FIG. 5 shows an example of the relationship between the feed water heater bypass flow rate and the feed water heater bypass valve opening. If the feed water heater bypass flow rate is determined based on FIG. 4, this flow rate ratio is secured. It suffices to select a possible feed water heater bypass valve opening.

The feed water heater bypass flow rate and the feed water heater bypass valve opening are determined depending on the feed water heater bypass valve flow rate characteristic.
It is shown as a characteristic. The feed water heater bypass flow rate may be the feed water heater bypass flow rate.

As described above, at the time of maintenance and inspection of the low-pressure feed water heater 5, the downstream low-pressure feed water bypass valve 19 provided in the downstream low-pressure feed water heater bypass system 20 is operated to open so that the downstream low-pressure feed water is supplied. It is possible to reduce the flow rate of the feed water passing through the heater 6 and reduce the flow rate of the heating steam of the low pressure side feed water heater 6 on the downstream side, and to operate the heating steam pipe, the feed water heater or the like at a flow velocity equal to or less than the restricted flow rate.

Therefore, the load restriction at the time of maintenance and inspection of the feedwater heater of the power plant is eased, and the feedwater heater bypass operation corresponding to the target turbine load is enabled.

There are cases where the maintenance and inspection of the feed water heater are carried out regularly and cases where it is necessary to carry out the work urgently. In either case, no load limitation is required, or the water supply system corresponding to the target load is not required. Since it can be operated, reliability as a stable power supply facility is secured and
Economic loss due to load limitation can be avoided.

[0024]

According to the present invention, there is an effect that it is possible to provide a water supply system of a steam power generation plant and a method of operating the same, in which load limitation can be eased during maintenance and inspection of the water supply heater.

[Brief description of drawings]

FIG. 1 shows a water supply system of a steam power plant that is an embodiment of the present invention.

FIG. 2 shows an example of a water supply system configuration of a general steam power plant.

FIG. 3 shows an example of a water supply system configuration of a general steam power plant.

FIG. 4 shows an example of a turbine load and feed water heater bypass flow rate ratio in the present embodiment.

FIG. 5 shows an example of feed water heater bypass flow rate and feed water heater bypass valve opening in this embodiment.

[Explanation of symbols]

1 ... Steam turbine, 2 ... Generator, 3 ... Condenser, 4 ... Condensate pump, 5 ... Feed water heater, 6 ... Downstream feed water heater, 7 ...
Water supply heater inlet valve, 8 ... Water supply heater outlet valve, 9 ... Water supply system, 10 ... Water supply heater bypass valve, 11 ... Water supply heater bypass system, 12 ... Heating steam inlet valve, 13 ... Heating steam system, 14 ... Downstream feedwater heater inlet valve, 15 ... Downstream feedwater heater outlet valve, 16 ... Downstream feedwater heater water supply system, 17
… Downstream heating steam inlet valve, 18… Downstream heating steam system,
19 ... Downstream side feed water heater bypass valve, 20 ... Downstream side feed water heater bypass system, 30 ... Bypass flow control device.

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) F22B 35/00 F22B 35/00 F F22D 5/34 F22D 5/34 Z G21D 3/00 G21D 3/00 M

Claims (7)

[Claims] 1. A first feed water heater, a second feed water heater installed downstream of the first feed water heater, a bypass system for bypassing the second feed water heater, and A water supply system for a steam power plant, comprising: a bypass valve installed in the bypass system for controlling the flow rate of the water supply that bypasses the second water heater. 2. A first low-pressure feed water heater, a second low-pressure feed water heater installed downstream of the first low-pressure feed water heater, and a bypass bypassing the second low-pressure feed water heater. And a bypass valve that is installed in the bypass system and that controls a flow rate of feed water that bypasses the second low-pressure feed water heater, wherein the bypass valve is the first valve during the isolated operation of the first feed water heater. 2. A water supply system for a steam power plant, characterized in that the water supplied to the low-pressure water heater of 2 is bypassed. 3. A first low-pressure feed water heater, a second low-pressure feed water heater installed downstream of the first low-pressure feed water heater, and a bypass bypassing the second low-pressure feed water heater. System, a bypass valve installed in the bypass system for controlling the flow rate of feed water that bypasses the second low-pressure feed water heater, and a bypass flow rate corresponding to the target turbine load during isolated operation of the first feed water heater. A control system for controlling the valve opening of the bypass valve so that the water supply system of the steam power plant. 4. A first low-pressure feed water heater, a second low-pressure feed water heater installed downstream of the first low-pressure feed water heater, and a bypass bypassing the second low-pressure feed water heater. System, a bypass valve installed in the bypass system for controlling the flow rate of feed water that bypasses the second low-pressure feed water heater, and a turbine load during the isolated operation of the first feed water heater to reduce the turbine load. 2. A water supply system for a steam power plant, comprising a control device for controlling a valve opening of the bypass valve so as to reduce a flow rate of water supplied to the low-pressure water heater. 5. A first low-pressure feed water heater, a second low-pressure feed water heater installed downstream of the first low-pressure feed water heater, and a bypass bypassing the second low-pressure feed water heater. A method for operating a water supply system of a steam power plant, comprising: a system and a bypass valve that is installed in the bypass system and that controls a flow rate of supply water that bypasses the second low-pressure water heater. In the isolated operation, the valve opening of the bypass valve is controlled to bypass the feed water supplied to the second low-pressure feed water heater, thereby operating the feed water system of the steam power plant. 6. A first low-pressure feed water heater, a second low-pressure feed water heater installed on the downstream side of the first low-pressure feed water heater, and a bypass bypassing the second low-pressure feed water heater. In a method of operating a water supply system of a steam power plant, the system including a system and a bypass valve installed in the bypass system for controlling a flow rate of the supply water for bypassing the second low-pressure feed water heater, and a bypass corresponding to a target turbine load. A method for operating a water supply system of a steam power plant, comprising controlling a valve opening degree of the bypass valve so as to obtain a flow rate. 7. A first low-pressure feed water heater, a second low-pressure feed water heater installed on the downstream side of the first low-pressure feed water heater, and a bypass bypassing the second low-pressure feed water heater. A method for operating a water supply system of a steam power plant, comprising: a system and a bypass valve that is installed in the bypass system and that controls a flow rate of supply water that bypasses the second low-pressure water heater. Of the bypass valve so as to reduce the turbine load during the isolated operation to reduce the flow rate of the feed water supplied to the second low-pressure feed water heater. Driving method.