JPH04252813A - Steam turbine arrangement - Google Patents

Abstract

PURPOSE:To provide a steam turbine system capable of storing all the heat of surplus steam by supplying the surplus steam extracted from a boiler separately to a high pressure deaerator and a low pressure deaerator and controlling the amount of the extracted steam. CONSTITUTION:Steam is extracted from a steam turbine 2, controlled with a high pressure control valve 10, and supplied to a high pressure deaerator 11 to heat and deaerate water fed from a feed water tank 15 through a high pressure feed water line 18. The extracted steam is also controlled to a low pressure with a low pressure control valve 12 to heat and deaerate water supplied through a low pressure feed water line 20. The deaerated water is stored in a deaerated water tank 25 and fed to a boiler 1. When surplus extracted steam is detected with a pressure detector 14, high pressure and low pressure feed water valves 19 and 21 are controlled so that the amount of deaerated water becomes expected deaerated water amount fed to the boiler 1 during the operation period in which steam is not extracted in excess. Deaerated water in the deaerated water tank 25 is supplied through a deaerated water return line 33 to the high pressure deaerator 11.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention includes a deaerator that heats and deaerates feed water supplied to a boiler using extracted steam from a steam turbine, and a deaerated water tank that stores deaerated water from the deaerator. In particular, the present invention relates to steam turbine equipment that heats and deaerates feed water using surplus extracted steam and stores heat of the surplus extracted steam.

0002

[Prior Art] A boiler is equipped with a boiler that evaporates supplied water to generate steam, and a steam turbine that is driven by the steam from the boiler. 2. Description of the Related Art Steam turbine equipment is known in which electric power is converted into electric power by a generator and supplied to a load, and extracted steam extracted from a turbine is supplied to a process via an extracted steam system.

[0003] In such steam turbine equipment, the feed water supplied to the boiler needs to be degassed to remove oxygen, carbon dioxide, etc. dissolved in the feed water, which can cause corrosion of equipment such as the boiler and turbine. For this purpose, the system is equipped with a deaerator that heats and deaerates the feed water using extracted steam supplied from the steam turbine via the extraction steam system, and a deaerated water tank that stores the deaerated water deaerated by the deaerator. ing.

[0004] Therefore, in operation of steam turbine equipment, water supplied from a water supply tank is sent to a deaerator to be deaerated, and this deaerated water is stored in a deaerated water tank. The stored degassed water is then supplied to the boiler and turned into steam, which drives the steam turbine.

[0005] By the way, when excess extracted steam is generated due to a decrease in the steam load such as a decrease in the amount of steam required by the process connected to the extracted steam system or a decrease in the electrical output from the generator, excess extracted steam is generated from the water supply tank. The amount of water supplied to the deaerator is increased to increase the amount of steam extracted from the turbine supplied for deaeration to generate deaeration water, and this deaeration water is stored in a deaeration water tank for heat storage. things are being done.

[0006]

[Problem to be solved by the invention] As mentioned above, when surplus extracted steam is generated during operation of steam turbine equipment, the amount of deaerated water obtained by increasing the amount of extracted steam for deaeration in the deaerator. is determined in proportion to the amount of excess steam. Therefore, the amount of deaerated water differs between the operating period of the steam turbine equipment in which excess extracted steam is not produced and the operating period in which excess extracted steam is produced. For this reason, even if surplus extracted steam is generated, a portion of it is released into the atmosphere, which poses a problem in that heat storage is not sufficient.

[0007] An object of the present invention is to provide steam turbine equipment that can store all of the excess steam.

[0008]

[Means for Solving the Problems] In order to solve the above problems, the present invention includes a boiler, a steam turbine driven by steam from the boiler, a water supply tank for storing water to be supplied to the boiler, and a steam turbine. A high-pressure deaerator that heats and deaerates water supplied from a water supply tank through a first water supply system using first steam whose pressure is controlled by a first pressure control valve on extracted steam extracted from a turbine; a low-pressure deaerator that heats and deaerates water supplied from a water supply tank through a second water supply system using a second steam whose pressure is controlled to be lower than the pressure of the first steam by a second pressure control valve; , a first water supply control valve provided in the first water supply system to control the flow rate of water to be supplied, and a second water supply control valve provided in the second water supply system to control the flow rate of water to be supplied. , a deaerated water tank that stores the deaerated water deaerated by the high-pressure and low-pressure deaerators and supplies it to the boiler, and a pressure sensor that detects the increase in bleed steam pressure due to the generation of excess bleed steam when the steam load is reduced. High-pressure and low-pressure deaeration is controlled by the detector and the first and second water supply control valves so that the amount of deaeration water supplied to the boiler during the operating period in which no excess bleed steam is generated is controlled by the first and second water supply control valves. The system shall be equipped with a control unit that controls the flow rate ratio of water supplied from the water supply tank to each of the water tanks to a planned value.

[0009] Furthermore, a degassed water return system is provided which is equipped with a degassed water flow rate control valve that supplies the degassed water in the degassed water tank to the high-pressure deaerator and controls the flow rate of this degassed water. do.

0010

[Operation] When the load of a steam turbine driven by steam from a boiler or the load of extracted steam extracted from the steam turbine, for example, the steam load of a process, is reduced, surplus steam is generated in the extracted steam. This surplus extracted steam is controlled by the first pressure control valve (hereinafter referred to as high pressure steam)
and the high pressure steam controlled by the second pressure control valve to produce low pressure steam at a lower pressure. and the first one from the water tank.
The water supplied through the second water supply system is heated and degassed by the high pressure steam in the high pressure deaerator, while the water supplied through the second water supply system is heated and degassed by the low pressure steam in the low pressure deaerator. I care.

By the way, the saturation temperature of degassed water heated and degassed in a high-pressure deaerator with high-pressure steam is higher than the saturation temperature of degassed water heated and degassed in a low-pressure deaerator with low-pressure steam. The thermal energy of the degassed water in the degasser is larger than that of the degassed water in the low-pressure deaerator, which is advantageous for heat storage. The amount caused by the deaerator is larger than that caused by the high pressure deaerator.

Utilizing this characteristic, when the steam load of the steam turbine is reduced and surplus extracted steam is generated, the amount of deaerated water is adjusted from the water supply tank to the expected amount of deaerated water to be supplied to the boiler during the operation period when no surplus extracted steam is generated. By controlling the flow rate ratio of water supplied to the high-pressure deaerator and the low-pressure deaerator to a planned value calculated in advance by the first water supply control valve and the second water supply control valve, it corresponds to the flow rate ratio. degassed water is produced in a high pressure deaerator and a low pressure deaerator. Note that heating deaeration in the high-pressure and low-pressure deaerators is carried out during the operating period when excess extracted steam is generated.

[0013] Degassed water degassed by the high pressure deaerator and the low pressure deaerator are mixed and stored in a degassed water tank. In this case, the amount of deaerated water stored in the deaerated water tank is determined by the planned flow rate ratio of the water from the water supply tank that supplies the high-pressure deaerator and the low-pressure deaerator to an operation that does not generate excess bleed steam. This is the amount of deaerated water required for the period.

Note that if there is a considerable amount of surplus extracted steam, the first water supply control valve is controlled and the second water supply control valve is closed, that is, the flow rate ratio is set to 1:0, and only the high-pressure deaerator is operated. By heating and deaerating the water from the water supply tank at , an amount of deaerated water with high thermal energy required during the operating period in which the surplus bleed steam is not generated can be obtained.

On the other hand, when there is little surplus steam, the first water supply control valve is closed and the second water supply control valve is controlled, that is, the flow rate ratio is set to 0:1 and the water supply tank is closed using only the low pressure deaerator. By heating and deaerating the water from the reactor, the amount of deaerated water required for an operating period with lower thermal energy but without producing excess bleed steam can be obtained.

Note that when there is no need to increase the amount of deaerated water stored in the deaerated water tank and there is excess extracted steam, this deaerated water is passed through the deaerated water return system and the deaerated water flow rate is controlled. By controlling the flow rate with a valve and supplying it to the high-pressure deaerator, this degassed water is heated and heated by the supplied surplus bleed steam, and is mixed with the high-temperature degassed water in the high-pressure deaerator to be degassed. The air is returned to the water tank. As a result, the temperature of the degassed water in the degassed water tank rises, making it possible to further store heat of excess extracted steam.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below based on the drawings. FIG. 1 is a system diagram of a steam turbine facility according to an embodiment of the present invention. In FIG. 1, 1 is a boiler, 2 is a steam turbine driven by steam passing through a steam supply system 3, and 4 is a steam turbine driven by steam passing through a steam supply system 3.
is a generator connected to the steam turbine 3 via a speed increaser 5. Note that 6 is an exhaust system that supplies exhaust steam from the steam turbine 2 to a condenser (not shown).

The extraction steam system 8 is connected to an intermediate stage of the steam turbine 2, a process 9, a high pressure deaerator 11, and a low pressure deaerator 13. In addition, the high pressure pressure control valve 10,
The low pressure pressure control valve 12 is connected to the high pressure, low pressure deaerator 11,
The pressure of the extracted steam supplied to 13 is controlled. Here, the pressure of the extracted steam supplied to the high-pressure deaerator 11 and controlled by the high-pressure pressure control valve 10 is lower than the pressure of the extracted steam supplied to the low-pressure deaerator 13 and controlled by the low-pressure pressure control valve 12. expensive. Note that 14 is a pressure detector that detects the pressure of the extracted steam flowing through the extracted steam system 8.

The water supply tank 15 stores condensate and make-up water from a condenser (not shown).

The water supply system 16 includes a supply pump 17, a high pressure water supply system 18 with a high pressure water supply control valve 19 connected downstream to the high pressure deaerator 11, and a low pressure water supply control valve 21 connected to the low pressure deaerator 13. It is branched into a low pressure water supply system 20,
Water consisting of condensate and make-up water in the water supply tank 15 is supplied by a supply pump 17 to the high pressure and low pressure deaerators 11 and 13, respectively.

The degassed water tank 25 contains degassed water in the high pressure deaerator 11 which is fed by a pump 26 through a high pressure degassed water supply system 27 and water is fed by a pump 28 through a low pressure degassed water supply system 29. It is mixed with deaerated water in the low pressure deaerator 13 and stored.

The boiler water supply system 30 is connected to the deaerated water tank 25 and the boiler 1, and includes a boiler water supply pump 31.
The degassed water in the degassed water tank 25 is supplied to the boiler 1.

The deaerated water return system 33 is connected to the deaerated water tank 25 and the high-pressure deaerator 11 with a deaerated water flow rate control valve 34 and a pump 35. The degassed water inside is returned to the high pressure deaerator 11.

The control unit 40 uses the pressure detector 14 to detect a rise in steam pressure due to excess extracted steam flowing through the extracted steam system 8, and uses a signal of this detected pressure increase to adjust the opening degrees of the high pressure and low pressure water supply control valves 19 and 21. High pressure water supply system 1
The high pressure water supply control valve 1 is set so that the flow rate ratio of water from the water supply tank 15 flowing into the water supply system 8 and the low pressure water supply system 20 is set to the above-mentioned planned value.
9 and a low pressure water supply control valve 21.

With this configuration, when the power load receiving power from the generator 5 and the steam load of the process 9 are reduced and surplus extracted steam is generated, this surplus extracted steam is used to reduce the water supply to the boiler 1. Deaeration is performed. This deaeration method will be explained below.

[0026] If surplus bleed steam is generated as described above,
The pressure of the extracted steam flowing into the extracted steam system 8 increases. This pressure increase is detected by the pressure detector 14, and a signal of the detected pressure increase is input to the control section 40.

In the control section 40, a flow rate ratio control device is activated by a signal indicating a detected pressure increase due to the amount of surplus steam, and an output signal from this device controls the high pressure water supply control valve 19 and the low pressure water supply control valve 21 to control the excess extracted steam. The opening degrees of the high-pressure and low-pressure water supply control valves 19 and 21 are controlled respectively to supply water from the water tank 15 to the high-pressure water supply system 18 and the low-pressure water supply system 20 so that the expected amount of deaerated water is supplied to the boiler during the operation period in which no deaeration occurs. The high-pressure and low-pressure deaerator 11 is controlled by controlling the flow rate ratio of water flowing through the
, 13 respectively.

The water that has flowed into the high-pressure deaerator 11 and the low-pressure deaerator 13 in this way flows through the extraction steam system 8 by the operation of the high-pressure pressure control valve 10 and the low-pressure pressure control valve 12, and then flows through the high-pressure deaerator 11 and the low-pressure deaerator 13, respectively. 11. The high-pressure and low-pressure excess extraction steam flowing into the low-pressure deaerator 13 heats and degasses. The degassed water is then pumped from the high pressure deaerator 11 to the pump 26.
The degassed water is then sent from the low-pressure deaerator 13 to the degassed water supply system 29 by the pump 28 to the degassed water tank 25, where it is stored.

The degassed water tank 25 stores degassed water that has been degassed in the high pressure deaerator 11 and the low pressure deaerator 13 during the operation period in which excess extracted steam is generated. Note that the amount of deaerated water stored in the deaerated water tank 25 during this operating period is the amount of deaerated water that is supplied to the boiler during the operating period in which no surplus bleed steam is generated. When the electric load and steam load are restored to their original values and excess extracted steam is no longer generated, the steam pressure in the extracted steam system 8 will return to its original value, so the pressure return is detected by the pressure detector 14, and control is performed based on this detection signal. By closing the high-pressure and low-pressure water supply control valves 19 and 21 by the flow rate ratio control device of the section 40, the high-pressure and low-pressure pressure control valves 10 and 12 are closed, and the degassing operation is stopped.

[0030] In this way, during the operation period when surplus extracted steam is generated, the degassed water stored in the deaerated water tank 25 from the high-pressure and low-pressure deaerators 11 and 13 is used during the operation period when surplus extracted steam is not generated. Boiler water supply system 3 by boiler water supply pump 31
It is supplied to the boiler 1 through 0. Then, the boiler 1 generates an amount of steam that corresponds to the power load and process steam load that do not generate surplus extracted steam, and supplies it to the steam turbine 2 via the steam supply system 3. At this time, all the steam flowing through the extraction steam system 8 is supplied to the process 9.

By the way, when the amount of surplus steam is considerably large, the flow rate control device of the control section 40 controls the high pressure water supply control valve 1.
9, close the low-pressure water supply control valve 21, that is, set the flow rate ratio to 1:0, and transfer water from the water supply tank 15 to the high-pressure deaerator 1.
1, and is heated and degassed in a high-pressure deaerator 11 using high-pressure surplus bleed steam controlled by a high-pressure pressure control valve 10. In this case as well, the amount of degassed water sent from the high-pressure deaerator 11 to the degassed water tank 25 and stored therein will be the amount required during the operating period in which no surplus bleed steam is generated, as described above.

Further, when the amount of surplus steam is small, the flow rate ratio control device of the control section 40 closes the high pressure water supply control valve 19 and controls the low pressure water supply control valve 21, that is, the flow rate ratio is 0:
1, the water from the water supply tank 15 is sent only to the low-pressure deaerator 13 with flow rate control, and is heated and degassed in the low-pressure deaerator 13 using low-pressure surplus extraction steam controlled by the low-pressure pressure control valve 12. . In this case as well, as mentioned above, the amount deaerated in the low pressure deaerator 13 is greater than that in the high pressure deaerator 11 for the same amount of surplus steam, so The amount of degassed water stored is the amount required during the operating period when no surplus bleed steam is generated, as described above.

Note that if there is surplus extracted steam when there is no need to increase the amount of deaerated water stored in the deaerated water tank 25, the deaerated water flow rate is increased by the pump 35 via the deaerated water return system 33. By controlling the flow rate with the control valve 36 and sending it to the high-pressure deaerator 11, the temperature of the sent deaerated water is raised by the surplus extracted steam sent to the high-pressure deaerator 11 for heating and deaeration. Since the steam is returned to the deaerated water tank 25 again, the excess steam can be further stored as heat.

[0034]

As is clear from the above description, according to the present invention, surplus extracted steam generated during operation of steam turbine equipment is converted into high-pressure steam and low-pressure steam by a pressure control valve, and is then used in a high-pressure deaerator and a low-pressure deaerator, respectively. The water from the water supply tank is supplied to the high-pressure deaerator and the low-pressure deaerator by controlling the high-pressure water supply control valve and the low-pressure water supply control valve to control the flow rate ratio so that no excess bleed steam is generated. By controlling the flow rate ratio such that the amount of deaerated water supplied to the boiler during the operation period is heated and deaerated by the high pressure steam and the low pressure steam, and this deaerated water is accumulated in the deaerated water tank. , since this is the amount of deaerated water supplied to the boiler during the operating period when no excess extracted steam is generated.
All excess extracted steam can be effectively stored as heat.

[0035] Furthermore, by sending the degassed water in the degassed water tank to the high-pressure deaerator, the degassed water is heated and heated by excess extracted steam flowing into the high-pressure deaerator. Therefore, the surplus extracted steam can be further stored as heat.

[Brief explanation of the drawing]

FIG. 1: System diagram of steam turbine equipment according to an embodiment of the present invention.

[Explanation of symbols]

1 Boiler 2 Steam turbine 8. Extraction steam system 10 High pressure pressure control valve 11 High pressure deaerator 12 Low pressure pressure control valve 13 Low pressure deaerator 15 Water tank 18 High pressure water supply system 19 High pressure water supply control valve 20 Low pressure water supply system 21 Low pressure water supply control valve 25 Deaerated water tank 33 Degassed water return system 34 Deaerated water flow control valve

Claims (2)

[Claims] Claim 1: A boiler, a steam turbine driven by steam from the boiler, a water supply tank that supplies water to the boiler, and a first pressure control valve that controls the pressure of extracted steam extracted from the steam turbine. a high-pressure deaerator that heats and deaerates the water supplied from the water supply tank through the first water supply system using the first steam, and a second pressure control valve that controls the extracted steam at a pressure lower than the pressure of the first steam. a low-pressure deaerator that heats and deaerates the water supplied from the water supply tank through the second water supply system using second steam controlled by the water supply system; a second water supply control valve provided in the second water supply system that controls the amount of water supplied; and a second water supply control valve that controls the amount of water supplied to the second water supply system, and stores the degassed water degassed by the high-pressure and low-pressure deaerators and supplies it to the boiler. A deaerated water tank, a pressure detector that detects an increase in extracted steam pressure due to the generation of surplus extracted steam when the steam load is reduced, and a pressure detector that detects the increase in extracted steam pressure due to the generation of excess extracted steam, and supplies it to the boiler during the operating period when excess extracted steam is not generated. and a control unit that controls the flow rate ratio of water supplied from the water supply tank to the high-pressure and low-pressure deaerators, respectively, to a planned value by controlling the first and second water supply control valves so that the expected amount of deaerated water is achieved. Steam turbine equipment characterized by: 2. The steam turbine equipment according to claim 1, further comprising a deaerated water flow rate control valve that supplies deaerated water in the deaerated water tank to the high-pressure deaerator and controls the flow rate of the deaerated water. Steam turbine equipment characterized by being equipped with a deaerated water return system.