Peaking system based on the exhaust steam coupling of the intermediate pressure cylinder of a steam turbine and its operation method

Abstract

The present invention discloses a peak shaving system based on the exhaust steam coupling of a steam turbine intermediate pressure cylinder and its operation method. The system includes a first conventional unitized generating set (13) and a second conventional unitized generating set (14); the first conventional unitized generating set (13) includes a first intermediate pressure cylinder (7), a first low pressure cylinder (8), a first condensate pump (11), and a first intermediate pressure cylinder exhaust steam control and isolation valve group (1), and the second conventional unitized generating set (14) includes a second intermediate pressure cylinder (9), a second low pressure cylinder (10), a second condensate pump (12), and a second intermediate pressure cylinder exhaust steam control and isolation valve group (2); the operation method can achieve flexible switching between the first conventional unitized generating set (13) and the second conventional unitized generating set (14). The present invention can improve the deep peak shaving capacity of the unit and increase the flexibility of the unit operation without technical transformation on the boiler side.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal power generation, and particularly relates to a peak shaving system based on the exhaust steam coupling of the intermediate pressure cylinder of a steam turbine and its operation method. Background Art

[0002] At present, large-capacity thermal power plants in China widely adopt the unit system operation method, that is, one boiler supplies steam to one steam turbine, and the steam turbine drives a generator to generate electricity, forming an independent power generation unit of boiler-steam turbine-generator. There is basically no horizontal connection between each power generation unit. Limited by the minimum stable combustion output of the coal-fired boiler without auxiliary fuel, the minimum electrical load of existing thermal power units is generally limited to about 30%-40%. Continuing to reduce it will have an adverse impact on the safe and continuous operation of the boiler. Chinese Patent Invention Publication Specification CN109653810A discloses a thermal power system with one boiler driving two turbines in a switching operation. By adding superheated steam and reheated steam bypasses and control valves, when one boiler fails, the other boiler is used to drive two steam turbines to generate electricity. At this time, the unit has a certain peak shaving ability, but the system layout is relatively complex, the operation flexibility is low, and the operability in the actual operation of the power plant is poor.

[0003] In recent years, with the continuous advancement of the upgrading and transformation of thermal power units, there is an urgent need to propose a thermal power system and an operation method that can realize the coupled connection between large-capacity thermal power units to enhance the flexibility of the unit to adapt to the dispatching electrical load command and improve the deep peak shaving ability of the unit. Summary of the Invention

[0004] Aiming at the problems existing in the prior art, the present invention provides a peak shaving system based on the exhaust steam coupling of the intermediate pressure cylinder of a steam turbine and its operation method, which can improve the deep peak shaving ability of the unit and increase the operation flexibility of the unit without technical transformation on the boiler side.

[0005] The present invention is realized through the following technical solutions:

[0006] A peak shaving system based on the exhaust steam coupling of the intermediate pressure cylinder of a steam turbine includes a first conventional unit system power generation set and a second conventional unit system power generation set;

[0007] The first conventional unit system power generation set includes a first intermediate pressure cylinder, a first low pressure cylinder, a first condensate pump, and a first intermediate pressure cylinder exhaust steam control and isolation valve group. The second conventional unit system power generation set includes a second intermediate pressure cylinder, a second low pressure cylinder, a second condensate pump, and a second intermediate pressure cylinder exhaust steam control and isolation valve group;

[0008] A medium pressure cylinder exhaust steam connection pipe is connected between the exhaust ports of the first intermediate pressure cylinder and the second intermediate pressure cylinder of the two steam turbines, and a medium pressure cylinder exhaust steam connection pipe control and isolation valve group is installed on the medium pressure cylinder exhaust steam connection pipe;

[0009] A first intermediate pressure cylinder exhaust control and isolation valve group is connected between the exhaust port of the first intermediate pressure cylinder and the steam inlet of the first low pressure cylinder of the two steam turbines, and a second intermediate pressure cylinder exhaust control and isolation valve group is connected between the exhaust port of the second intermediate pressure cylinder and the steam inlet of the second low pressure cylinder;

[0010] A low-pressure feed water connection pipe is connected between the outlets of the first condensate pumps of the two steam turbines and the outlets of the second condensate pumps, and a low-pressure feed water connection pipe control and isolation valve group is installed on the low-pressure feed water connection pipe.

[0011] A further improvement of the present invention is that the power generation capacities of the first conventional unit type generating set and the second conventional unit type generating set are the same, the capacities are comparable, and the equipment types and thermal system designs are consistent.

[0012] A further improvement of the present invention is that the operating states of the first conventional unit type generating set and the second conventional unit type generating set are that both boilers and both steam turbines are in the operating state.

[0013] A further improvement of the present invention is that the exhaust steam of the first intermediate pressure cylinder of the first conventional unit type generating set can enter the second low pressure cylinder of the second conventional unit type generating set through the intermediate pressure cylinder exhaust connection pipe to do work.

[0014] A further improvement of the present invention is that the exhaust steam of the second intermediate pressure cylinder of the second conventional unit type generating set can enter the first low pressure cylinder of the first conventional unit type generating set through the intermediate pressure cylinder exhaust connection pipe to do work.

[0015] A further improvement of the present invention is that the condensate water at the outlet of the first condensate pump of the first conventional unit type generating set enters the low-pressure feed water system of the second conventional unit type generating set through the low-pressure feed water connection pipe to maintain the stable water level of the deaerator of the second conventional unit type generating set.

[0016] A further improvement of the present invention is that the condensate water at the outlet of the second condensate pump of the second conventional unit type generating set enters the low-pressure feed water system of the first conventional unit type generating set through the low-pressure feed water connection pipe to maintain the stable water level of the deaerator of the first conventional unit type generating set.

[0017] A peak shaving system operation method based on the coupling of the intermediate pressure cylinder exhaust steam of a steam turbine, which is based on the peak shaving system based on the coupling of the intermediate pressure cylinder exhaust steam of a steam turbine, includes the following steps:

[0018] Step 1: The first conventional unit-type generator set and the second conventional unit-type generator set operate normally, the first medium-pressure cylinder exhaust control and isolation valve group of the first conventional unit-type generator set are in an open state; the second medium-pressure cylinder exhaust control and isolation valve group of the second conventional unit-type generator set are in an open state; the medium-pressure cylinder exhaust connection pipe control and isolation valve group of the medium-pressure cylinder exhaust connection pipe are in a closed state; the low-pressure water supply connection pipe control and isolation valve group of the low-pressure water supply connection pipe are in a closed state;

[0019] Step 2: The intermediate pressure cylinder exhaust pipe of the intermediate pressure cylinder exhaust pipe is controlled and the isolation valve group is opened; the first intermediate pressure cylinder exhaust pipe of the first conventional unit-type generator set is controlled and the isolation valve group is slowly closed; the low pressure water supply pipe of the low pressure water supply pipe is controlled and the isolation valve group is slowly opened; the water level of the deaerator of the first conventional unit-type generator set is maintained stable; and the deep peak-shaving operation of the first conventional unit-type generator set is realized;

[0020] Step 3, the intermediate pressure cylinder exhaust communication pipe control and isolation valve group of the intermediate pressure cylinder exhaust communication pipe are maintained open; the first intermediate pressure cylinder exhaust control and isolation valve group of the first conventional unit-type generator set are slowly opened; the second intermediate pressure cylinder exhaust control and isolation valve group of the second conventional unit-type generator set are slowly closed; the low-pressure water supply communication pipe control and isolation valve group are maintained open; the water level of the deaerator of the second conventional unit-type generator set is maintained stable; and the deep peak-shaving operation of the second conventional unit-type generator set is achieved.

[0021] A further improvement of the present invention is that the first conventional unit-based generator set and the second conventional unit-based generator set are both in a grid-connected power generation state, and any one of the generator sets can participate in deep peak regulation at any time.

[0022] A further improvement of the present invention is that the operating states of the first conventional unit-based generator set and the second conventional unit-based generator set can be switched with each other.

[0023] Compared with the prior art, the present invention has the following beneficial technical effects:

[0024] The present invention realizes the switching of deep peak-shaving operation mode of any unit by adding medium-pressure cylinder exhaust connecting pipe and low-pressure water supply connecting pipe; when a unit is in deep peak-shaving operation, its low-pressure cylinder steam inlet flow rate is reduced, and the work done by the low-pressure cylinder is significantly reduced, and the deep peak-shaving capacity of the unit is increased. Utilizing the present invention, under deep peak-shaving operation conditions, most of the steam inlet volume of the low-pressure cylinder of one unit can be transported to the low-pressure cylinder of another unit, achieving a smaller technical output of one unit. It enhances the flexibility of the unit to adapt to the dispatching electric load instructions, increases the deep peak-shaving electricity price income of the power plant, and improves the production and operation efficiency of the power plant. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1It is a schematic diagram of the thermal system of the peak shaving system based on the exhaust steam coupling of the intermediate pressure cylinder in the steam turbine described in the embodiments of the present invention.

[0026] Explanation of reference numerals:

[0027] 1. First intermediate pressure cylinder exhaust steam control and isolation valve group; 2. Second intermediate pressure cylinder exhaust steam control and isolation valve group; 3. Intermediate pressure cylinder exhaust steam connection pipe control and isolation valve group; 4. Intermediate pressure cylinder exhaust steam connection pipe; 5. Low-pressure feed water connection pipe; 6. Low-pressure feed water connection pipe control and isolation valve group; 7. First intermediate pressure cylinder; 8. First low-pressure cylinder; 9. Second intermediate pressure cylinder; 10. Second low-pressure cylinder; 11. First condensate pump; 12. Second condensate pump; 13. First conventional unit type generator set; 14. Second conventional unit type generator set. Specific implementation manners

[0028] The following further elaborates on the present invention in combination with specific implementation manners, which is an explanation rather than a limitation of the present invention.

[0029] As Figure 1 shown, the peak shaving system based on the exhaust steam coupling of the intermediate pressure cylinder in the steam turbine provided by the present invention includes a first conventional unit type generator set 13 and a second conventional unit type generator set 14 with the same capacity, equipment type and thermal system.

[0030] The first conventional unit type generator set 13 includes a first intermediate pressure cylinder 7, a first low-pressure cylinder 8, a first condensate pump 11 and a first intermediate pressure cylinder exhaust steam control and isolation valve group 1. The second conventional unit type generator set 14 includes a second intermediate pressure cylinder 9, a second low-pressure cylinder 10, a second condensate pump 12 and a second intermediate pressure cylinder exhaust steam control and isolation valve group 2. A middle pressure cylinder exhaust steam connection pipe 4 is connected between the exhaust ports of the first intermediate pressure cylinder 7 and the second intermediate pressure cylinder 9 of the two steam turbines, and a middle pressure cylinder exhaust steam connection pipe control and isolation valve group 3 is installed on the middle pressure cylinder exhaust steam connection pipe 4. A first intermediate pressure cylinder exhaust steam control and isolation valve group 1 is connected between the exhaust port of the first intermediate pressure cylinder 7 of the two steam turbines and the steam inlet of the first low-pressure cylinder 8, and a second intermediate pressure cylinder exhaust steam control and isolation valve group 2 is connected between the exhaust port of the second intermediate pressure cylinder 9 and the steam inlet of the second low-pressure cylinder 10. A low-pressure feed water connection pipe 5 is connected between the outlets of the first condensate pump 11 and the second condensate pump 12 of the two steam turbines, and a low-pressure feed water connection pipe control and isolation valve group 6 is installed on the low-pressure feed water connection pipe 5.

[0031] Preferably, a middle pressure cylinder exhaust steam connection pipe control and isolation valve group 3 is installed on the middle pressure cylinder exhaust steam connection pipe 4 to realize the switching of the deep peak shaving operation mode of a single unit;

[0032] Preferably, a first intermediate-pressure cylinder exhaust steam control and isolation valve group 1 is installed on the intermediate-pressure cylinder exhaust steam pipe of the first conventional unit steam turbine generator set 13. This valve group can control the steam inlet volume of the first low-pressure cylinder 8 and adjust the output of the first low-pressure cylinder 8 of the first conventional unit steam turbine generator set 13;

[0033] Preferably, a second intermediate-pressure cylinder exhaust steam control and isolation valve group 2 is installed on the intermediate-pressure cylinder exhaust steam pipe of the second conventional unit steam turbine generator set 14. This valve group can control the steam inlet volume of the second low-pressure cylinder 10 and adjust the output of the second low-pressure cylinder 10 of the second conventional unit steam turbine generator set 14;

[0034] Preferably, a low-pressure feed water connection pipe control and isolation valve group 6 is installed on the low-pressure feed water connection pipe 5, which is used to adjust the low-pressure feed water flow of the two units during the deep peak shaving process and maintain the stable water level of the deaerator.

[0035] The operation method of the peak shaving system based on the coupling of the intermediate-pressure cylinder exhaust steam of the steam turbine provided by the present invention includes the following steps:

[0036] Step 1, the first conventional unit steam turbine generator set 13 and the second conventional unit steam turbine generator set 14 operate normally. The first intermediate-pressure cylinder exhaust steam control and isolation valve group 1 of the first conventional unit steam turbine generator set 13 is in the open state; the second intermediate-pressure cylinder exhaust steam control and isolation valve group 2 of the second conventional unit steam turbine generator set 14 is in the open state; the intermediate-pressure cylinder exhaust steam connection pipe control and isolation valve group 3 of the intermediate-pressure cylinder exhaust steam connection pipe 4 is in the closed state; the low-pressure feed water connection pipe control and isolation valve group 6 of the low-pressure feed water connection pipe 5 is in the closed state;

[0037] Step 2, the intermediate-pressure cylinder exhaust steam connection pipe control and isolation valve group 3 of the intermediate-pressure cylinder exhaust steam connection pipe 4 is opened; the first intermediate-pressure cylinder exhaust steam control and isolation valve group 1 of the first conventional unit steam turbine generator set 13 is slowly closed; the low-pressure feed water connection pipe control and isolation valve group 6 of the low-pressure feed water connection pipe 5 is slowly opened; maintain the stable water level of the deaerator of the first conventional unit steam turbine generator set 13; realize the deep peak shaving operation of the first conventional unit steam turbine generator set 13;

[0038] Step 3, the intermediate-pressure cylinder exhaust steam connection pipe control and isolation valve group 3 of the intermediate-pressure cylinder exhaust steam connection pipe 4 remains open; the first intermediate-pressure cylinder exhaust steam control and isolation valve group 1 of the first conventional unit steam turbine generator set 13 is slowly opened; the second intermediate-pressure cylinder exhaust steam control and isolation valve group 2 of the second conventional unit steam turbine generator set 14 is slowly closed; the low-pressure feed water connection pipe control and isolation valve group 6 remains open; maintain the stable water level of the deaerator of the second conventional unit steam turbine generator set 14; realize the deep peak shaving operation of the second conventional unit steam turbine generator set 14.

[0039] The above are only the preferred specific embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or applied to multiple units, or directly or indirectly used in other related technical fields, shall similarly be included within the patent protection scope of the present invention.

Claims

1. Operating method of a peak shaving system based on the coupling of the exhaust steam of the intermediate pressure cylinder of a steam turbine, characterized in that, The method adopts a peak load regulation system based on steam turbine intermediate pressure cylinder exhaust coupling, comprising a first conventional unit-type generator set (13) and a second conventional unit-type generator set (14); The first conventional unit-type generator set (13) comprises a first intermediate-pressure cylinder (7), a first low-pressure cylinder (8), a first condensate pump (11) and a first intermediate-pressure cylinder exhaust steam control and isolation valve group 1, and the second conventional unit-type generator set (14) comprises a second intermediate-pressure cylinder (9), a second low-pressure cylinder (10), a second condensate pump (12) and a second intermediate-pressure cylinder exhaust steam control and isolation valve group 2; An intermediate pressure cylinder exhaust communication pipe (4) is connected between the exhaust port of the first intermediate pressure cylinder (7) and the exhaust port of the second intermediate pressure cylinder (9) of the two steam turbines, and an intermediate pressure cylinder exhaust communication pipe control and isolation valve group 3 is installed on the intermediate pressure cylinder exhaust communication pipe (4); A first intermediate pressure cylinder exhaust control and isolation valve group 1 is connected between the exhaust port of the first intermediate pressure cylinder (7) and the steam inlet of the first low pressure cylinder (8) of the two steam turbines, and a second intermediate pressure cylinder exhaust control and isolation valve group 2 is connected between the exhaust port of the second intermediate pressure cylinder (9) and the steam inlet of the second low pressure cylinder (10); A low-pressure water supply connection pipe (5) is connected between the outlet of the first condensate pump (11) and the outlet of the second condensate pump (12) of the two steam turbines, and a low-pressure water supply connection pipe control and isolation valve group 6 is installed on the low-pressure water supply connection pipe (5); The method comprises the following steps: Step 1: the first conventional unit-based generator set (13) and the second conventional unit-based generator set (14) operate normally, and the first intermediate pressure cylinder exhaust control and isolation valve group 1 of the first conventional unit-based generator set (13) are in an open state; The second medium-pressure cylinder exhaust control and isolation valve group 2 of the second conventional unit-type generator set (14) are in an open state; the medium-pressure cylinder exhaust connection pipe control and isolation valve group 3 of the medium-pressure cylinder exhaust connection pipe (4) are in a closed state; the low-pressure water supply connection pipe control and isolation valve group 6 of the low-pressure water supply connection pipe (5) are in a closed state; Step 2, the intermediate pressure cylinder exhaust communication pipe (4) of the intermediate pressure cylinder exhaust communication pipe is controlled and the isolation valve group 3 is opened; The first medium-pressure cylinder exhaust steam control of the first conventional unit-type generator set (13) and the isolation valve group 1 are slowly closed; the low-pressure water supply connecting pipe (5) and the isolation valve group 6 are slowly opened; the water level of the deaerator of the first conventional unit-type generator set (13) is maintained stable; and the deep peak-shaving operation of the first conventional unit-type generator set (13) is achieved; Step 3, the intermediate pressure cylinder exhaust communication pipe (4) of the intermediate pressure cylinder exhaust communication pipe is controlled and the isolation valve group 3 is kept open; the first intermediate pressure cylinder exhaust control and isolation valve group 1 of the first conventional unit-type generator set (13) are slowly opened; The second medium-pressure cylinder exhaust steam control and isolation valve group 2 of the second conventional unit-type generator set (14) are slowly closed; the low-pressure water supply connecting pipe is controlled and the isolation valve group 6 is kept open; the water level of the deaerator of the second conventional unit-type generator set (14) is maintained stable; and the deep peak-shaving operation of the second conventional unit-type generator set (14) is achieved.

2. The operation method of the peak shaving system based on the exhaust steam coupling of the intermediate pressure cylinder of the steam turbine according to claim 1, characterized in that Both the first conventional unit type generating set (13) and the second conventional unit type generating set (14) are in the grid-connected power generation state, and any one of the generating sets can participate in deep peak shaving at any time.

3. The operation method of the peak shaving system based on the exhaust steam coupling of the intermediate pressure cylinder of the steam turbine according to claim 1, wherein The operating states of the first conventional unit type generating set (13) and the second conventional unit type generating set (14) can be switched with each other.

4. The method for operating a peak load regulation system based on steam turbine intermediate pressure cylinder exhaust coupling according to claim 1, characterized in that: The first conventional unit type generating set (13) and the second conventional unit type generating set (14) have the same power generation capacity, equivalent capacity, and the same equipment type and thermal system design.

5. The method for operating a peak load regulation system based on steam turbine intermediate pressure cylinder exhaust coupling according to claim 1, characterized in that: The operating states of the first conventional unit type generating set (13) and the second conventional unit type generating set (14) are that both boilers and both steam turbines are in the operating state.

6. The method for operating a peak load regulation system based on steam turbine intermediate pressure cylinder exhaust coupling according to claim 1, characterized in that: The exhaust steam of the first intermediate pressure cylinder (7) of the first conventional unit type generating set (13) can enter the second low pressure cylinder (10) of the second conventional unit type generating set (14) through the intermediate pressure cylinder exhaust connection pipe (4) to do work.

7. The method for operating a peak load regulation system based on steam turbine intermediate pressure cylinder exhaust coupling according to claim 1, characterized in that: The exhaust steam of the second intermediate pressure cylinder (9) of the second conventional unit type generating set (14) can enter the first low pressure cylinder (8) of the first conventional unit type generating set (13) through the intermediate pressure cylinder exhaust connection pipe (4) to do work.

8. The method for operating a peak load regulation system based on steam turbine intermediate pressure cylinder exhaust coupling according to claim 1, characterized in that: The condensate water at the outlet of the first condensate pump (11) of the first conventional unit type generating set (13) enters the low pressure feed water system of the second conventional unit type generating set (14) through the low pressure feed water connection pipe (5) to maintain the stable water level of the deaerator of the second conventional unit type generating set (14).

9. The method for operating a peak load regulation system based on steam turbine intermediate pressure cylinder exhaust coupling according to claim 1, characterized in that: The condensate water at the outlet of the second condensate pump (12) of the second conventional unit type generating set (14) enters the low pressure feed water system of the first conventional unit type generating set (13) through the low pressure feed water connection pipe (5) to maintain the stable water level of the deaerator of the first conventional unit type generating set (13).

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