Turbine system and power generation system including same

Abstract

The invention provides a steam turbine system and a power generation system comprising the steam turbine system. The steam turbine system comprises a waste heat boiler, and a heat exchanger of the waste heat boiler is communicated with a steam turbine set; the high-pressure cylinder is communicated with a first steam outlet end of the waste heat boiler, so that high-pressure steam output by the waste heat boiler expands to do work in the high-pressure cylinder; the low-pressure cylinder communicates with the second steam outlet end of the waste heat boiler and the high-pressure cylinder, so that first low-pressure steam output by the waste heat boiler and second low-pressure steam output by the high-pressure cylinder expand to do work in the low-pressure cylinder; wherein the waste heat boiler communicates with the low-pressure cylinder through a low-pressure pipeline, at least two steam inlets communicating with the waste heat boiler are formed in the low-pressure cylinder in the axial direction at intervals, and the low-pressure pipeline is constructed to selectively open one of the multiple steam inlets according to the pressure of second low-pressure steam output by the high-pressure cylinder; the pressure difference value between the first low-pressure steam and the steam inlet in the open state is within the preset pressure difference range.

Description

Technical Field

[0001] At least one embodiment of the present invention relates to the technical field of steam turbine systems, and in particular to a steam turbine system and a power generation system including the steam turbine system. Background Art

[0002] In the existing gas-steam combined cycle power generation system, the "two-to-one" type unit consisting of two gas turbines and one steam turbine system is a typical configuration form. Each gas turbine and the corresponding waste heat boiler form a gas turbine unit, and the two gas turbine units jointly drive a steam turbine system to operate. The gas turbine of the "two-to-one" type unit has a large exhaust flow rate and high exhaust temperature. The waste heat boiler usually adopts a dual-pressure steam-water system to improve the heat exchange efficiency. The high-pressure steam and low-pressure steam generated by it enter the high-pressure cylinder and low-pressure cylinder of the steam turbine system respectively to expand and do work, thereby achieving a higher cycle thermal efficiency.

[0003] When the "two-on-one" type unit is transformed into "one-on-one" operation, that is, when one gas turbine unit is shut down and the other gas turbine unit is running at full load, the steam parameters provided by the waste heat boiler remain unchanged at the rated value, but because the steam flow is reduced by half, the turbine system is reduced to 50% load operation, so that the steam pressure at the steam inlet output from the high-pressure cylinder to the low-pressure cylinder is reduced to about half of the full-load condition due to the load reduction. At this time, in order to match the pressure of the low-pressure steam output from the waste heat boiler to the steam inlet of the low-pressure cylinder with the pressure of the steam output from the high-pressure cylinder to the steam inlet of the low-pressure cylinder, the low-pressure steam needs to be throttled and reduced in pressure before it can be replenished into the low-pressure cylinder of the turbine system, resulting in energy loss. Summary of the invention

[0004] In view of this, the present invention provides a steam turbine system, which reduces energy loss in the process of low-pressure steam output by a waste heat boiler flowing into a low-pressure cylinder when the steam turbine system is underloaded.

[0005] According to an embodiment of the present invention, a steam turbine system is provided, comprising: a waste heat boiler, a heat exchanger of which is connected to a steam turbine unit; a high-pressure cylinder, which is connected to a first steam outlet end of the waste heat boiler, so that the high-pressure steam output by the waste heat boiler expands inside the high-pressure cylinder to do work; and a low-pressure cylinder, which is connected to a second steam outlet end of the waste heat boiler and the high-pressure cylinder, respectively, so that the first low-pressure steam output by the waste heat boiler and the second low-pressure steam output by the high-pressure cylinder expand inside the low-pressure cylinder to do work; wherein the waste heat boiler is connected to the low-pressure cylinder through a low-pressure pipeline, and at least two steam inlets connected to the waste heat boiler are arranged at intervals in the axial direction on the low-pressure cylinder, and the low-pressure pipeline is configured to select one of the multiple steam inlets to be opened according to the pressure of the second low-pressure steam output by the high-pressure cylinder, so that the pressure difference between the first low-pressure steam and the steam inlet in an open state is within a preset pressure difference range.

[0006] According to an embodiment of the present invention, a plurality of blade stages are sequentially arranged inside the low-pressure cylinder along the axial direction from upstream to downstream, and at least one blade stage is spaced between two adjacent steam inlets; wherein, when the steam turbine unit is operating at full load, the first low-pressure steam flows into the low-pressure cylinder through the steam inlet located downstream; and when the steam turbine unit is operating at underload, the first low-pressure steam flows into the low-pressure cylinder through the steam inlet located upstream.

[0007] According to an embodiment of the present invention, the low-pressure pipeline includes a main steam circuit and at least two branch steam circuits, and each of the branch steam circuits is connected to one of the steam inlets.

[0008] According to an embodiment of the present invention, the preset pressure difference range is 0.5-1.0ata.

[0009] According to an embodiment of the present invention, a low-pressure steam inlet valve is provided on the main steam circuit to control the on-off of the main steam circuit; a low-pressure regulating valve is provided on each branch steam circuit to control the opening and closing of the branch steam circuit and to adjust the flow rate of the first low-pressure steam in the branch steam circuit.

[0010] According to an embodiment of the present invention, the high-pressure cylinder is connected to the low-pressure cylinder via a connecting pipeline.

[0011] According to an embodiment of the present invention, the high-pressure cylinder and the low-pressure cylinder form a mutually connected whole.

[0012] According to an embodiment of the present invention, the waste heat boiler is connected to the high-pressure cylinder via a high-pressure pipeline, and a high-pressure steam inlet valve and a high-pressure regulating valve are provided on the high-pressure pipeline.

[0013] According to an embodiment of the present invention, the turbine system further comprises an exhaust steam cold end, wherein the exhaust steam cold end is connected to the low-pressure cylinder and is suitable for receiving circulating exhaust steam.

[0014] According to an embodiment of the present invention, there is provided a power generation system, comprising: a steam turbine unit, comprising at least two gas turbines; the steam turbine system described in the above embodiment, wherein the working steam of the steam turbine system is provided by a waste heat boiler connected to the steam turbine unit; and a generator, connected to the steam turbine system, which, under the action of the steam turbine system, converts the kinetic energy of the steam turbine unit into electrical energy of the generator.

[0015] According to the steam turbine system of the above-mentioned embodiment of the present invention, at least two steam inlets connected to the waste heat boiler are arranged on the low-pressure cylinder in an axial direction at intervals, and the low-pressure pipeline is constructed to select one of the multiple steam inlets to open according to the pressure of the second low-pressure steam output by the high-pressure cylinder, so that the pressure difference between the first low-pressure steam and the steam inlet in the open state is within a preset pressure difference range, thereby reducing the energy loss in the process of the first low-pressure steam flowing into the low-pressure cylinder. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic diagram of a first embodiment of a generator system according to an embodiment of the present invention; and

[0017] Figure 2 1 is a schematic diagram of the principle of a second embodiment of a generator system according to an embodiment of the present invention.

[0018] In the figure:

[0019] 1-waste heat boiler; 11-second steam outlet; 12-first steam outlet;

[0020] 2- High pressure cylinder;

[0021] 3- low pressure cylinder; 31- steam inlet; 32- blade stage;

[0022] 4 low pressure pipeline;

[0023] 41-main steam circuit; 411-low-pressure steam inlet valve;

[0024] 42-branch steam circuit; 421-low pressure regulating valve;

[0025] 43-pressure measuring instrument;

[0026] 5-Connect the pipeline;

[0027] 6-high-pressure pipeline; 61-high-pressure steam inlet valve; 62-high-pressure regulating valve;

[0028] 7-Exhaust cold end;

[0029] 8- Generator. DETAILED DESCRIPTION

[0030] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0031] According to the inventive concept of one aspect of the present invention, a steam turbine system is provided, comprising: a waste heat boiler, a heat exchanger of the waste heat boiler being connected to a steam turbine unit; a high-pressure cylinder being connected to a first steam outlet end of the waste heat boiler, so that the high-pressure steam outputted by the waste heat boiler expands inside the high-pressure cylinder to do work; and a low-pressure cylinder being connected to a second steam outlet end of the waste heat boiler and the high-pressure cylinder, respectively, so that the first low-pressure steam outputted by the waste heat boiler and the second low-pressure steam outputted by the high-pressure cylinder expand inside the low-pressure cylinder to do work; wherein the waste heat boiler is connected to the low-pressure cylinder through a low-pressure pipeline, at least two steam inlets connected to the waste heat boiler are arranged at intervals in an axial direction on the low-pressure cylinder, and the low-pressure pipeline is configured to select one of a plurality of steam inlets to open according to the pressure of the second low-pressure steam outputted by the high-pressure cylinder, so that the pressure difference between the first low-pressure steam and the steam inlet in an open state is within a preset pressure difference range.

[0032] Figure 1 is a schematic diagram of the principle of a first embodiment of a generator system according to an embodiment of the present invention; Figure 2 1 is a schematic diagram of the principle of a second embodiment of a generator system according to an embodiment of the present invention.

[0033] According to an exemplary embodiment of the present invention, please refer to Figure 1-Figure 2 , a steam turbine system is provided, comprising a waste heat boiler 1, a high pressure cylinder 2 and a low pressure cylinder 3. The heat exchanger of the waste heat boiler 1 is connected to the steam turbine unit. The high pressure cylinder 2 is connected to the first steam outlet 12 of the waste heat boiler 1, so that the high pressure steam output by the waste heat boiler 1 expands inside the high pressure cylinder 2 to do work. The low pressure cylinder 3 is respectively connected to the second steam outlet 11 of the waste heat boiler 1 and the high pressure cylinder 2, so that the first low pressure steam output by the waste heat boiler 1 and the second low pressure steam output by the high pressure cylinder 2 expand inside the low pressure cylinder 3 to do work. Among them, the waste heat boiler 1 is connected to the low pressure cylinder 3 through a low pressure pipeline 4, and at least two steam inlets 31 connected to the waste heat boiler 1 are arranged at intervals along the axial direction on the low pressure cylinder 3, and the low pressure pipeline 4 is configured to select one of the multiple steam inlets 31 to be opened according to the pressure of the second low pressure steam output by the high pressure cylinder 2, so that the pressure difference between the first low pressure steam and the steam inlet 31 in the open state is within a preset pressure difference range.

[0034] In this embodiment, at least two steam inlets 31 connected to the waste heat boiler 1 are arranged at intervals along the axial direction on the low-pressure cylinder 3, and the low-pressure pipeline 4 is constructed to select one of the multiple steam inlets 31 to open according to the pressure of the second low-pressure steam output by the high-pressure cylinder 2, so that the pressure difference between the first low-pressure steam and the steam inlet 31 in the open state is within a preset pressure difference range, thereby avoiding the need to throttle and reduce the pressure of the first low-pressure steam based on the pressure matching of the first low-pressure steam and the second low-pressure steam, thereby reducing the energy loss in the process of the first low-pressure steam flowing into the low-pressure cylinder 3.

[0035] It should be noted that, in this embodiment, the high-pressure steam output by the waste heat boiler 1 has high pressure, high temperature and large flow rate, and flows through the high-pressure cylinder 2 and the low-pressure cylinder 3 of the steam turbine system in sequence, and expands and works inside the high-pressure cylinder 2 and the low-pressure cylinder 3. The low-pressure steam output by the waste heat boiler 1 has low pressure, low temperature and small flow rate, and expands and works only in the low-pressure cylinder 3 of the steam turbine system. At the steam inlet 31 of the low-pressure cylinder 3, the pressure of the first low-pressure steam and the second low-pressure steam are required to be strictly matched, and the pressure of the first low-pressure steam should be slightly higher than the pressure of the second low-pressure steam flowing to the steam inlet 31 of the low-pressure cylinder 3. If the pressure of the first low-pressure steam is too low, it will not be replenished. If the pressure of the first low-pressure steam is too high, the flow upstream of the steam inlet 31 will be deteriorated. The difference between the temperature of the first low-pressure steam and the temperature of the second low-pressure steam should be less than the limit value, otherwise it will cause a large local thermal stress, wherein the limit value is preferably 40°C.

[0036] Furthermore, through the above-mentioned configuration, the pressure and temperature parameters of the first low-pressure steam and the second low-pressure steam are more matched, thereby reducing the local thermal stress caused by the temperature difference.

[0037] In some exemplary embodiments, referring to Figure 1-Figure 2 , a plurality of blade stages 32 are sequentially arranged inside the low-pressure cylinder 3 from upstream to downstream along the axial direction, and at least one blade stage 32 is spaced between two adjacent steam inlets 31. When the steam turbine unit is running at full load, the first low-pressure steam flows into the low-pressure cylinder 3 through the downstream steam inlet 31. When the steam turbine unit is running at underload, the first low-pressure steam flows into the low-pressure cylinder 3 through the upstream steam inlet 31.

[0038] Through the above arrangement, the first low-pressure steam expands and performs work in more blade stages 32 inside the low-pressure cylinder 3 to increase the output power. This avoids the need to throttle and reduce the pressure of the first low-pressure steam due to the pressure matching between the first low-pressure steam and the second low-pressure steam, which causes energy loss. Furthermore, the cycle thermal efficiency of the steam turbine system is improved to a certain extent.

[0039] It should be noted that, in this embodiment, the direction from upstream to downstream is Figure 1 The direction indicated by arrow A.

[0040] In some exemplary embodiments, referring to Figure 1-Figure 2 The low-pressure pipeline 4 includes a main steam circuit 41 and at least two branch steam circuits 42 , and each branch steam circuit 42 is connected to a steam inlet 31 .

[0041] Through the above-mentioned setting method, according to different operating conditions of the steam turbine unit, the first low-pressure steam flows into the low-pressure cylinder 3 through different steam inlets 31 through different branch steam paths 42 to match the first low-pressure steam with the second low-pressure steam under different operating conditions of the steam turbine unit.

[0042] In some exemplary embodiments, the preset pressure difference range is 0.5-1.0 ata.

[0043] In some exemplary embodiments, referring to Figure 1-Figure 2 The main steam circuit 41 is provided with a low-pressure steam inlet valve 411 to control the on-off of the main steam circuit 41. Each branch steam circuit 42 is provided with a low-pressure regulating valve 421 to control the on-off of the branch steam circuit 42 and to adjust the flow rate of the first low-pressure steam in the branch steam circuit 42.

[0044] It should be noted that, in this embodiment, a pressure measuring gauge 43 is provided on the main steam circuit 41 and each branch steam circuit 42 to detect the pressure value of the first low-pressure steam flowing through the main steam circuit 41 and each branch steam circuit 42 .

[0045] In some exemplary embodiments, referring to Figure 1 The high-pressure cylinder 2 is connected to the low-pressure cylinder 3 through a connecting pipe 5.

[0046] In some exemplary embodiments, referring to Figure 2 The high-pressure cylinder 2 and the low-pressure cylinder 3 form an interconnected whole.

[0047] In some exemplary embodiments, referring to Figure 1-Figure 2 The waste heat boiler 1 is connected to the high-pressure cylinder 2 through a high-pressure pipeline 6, and a high-pressure steam inlet valve 61 and a high-pressure regulating valve 62 are provided on the high-pressure pipeline 6.

[0048] It should be noted that, in this embodiment, pressure measuring gauges 43 are respectively provided at the steam outlet end of the high-pressure pipeline 6 and the high-pressure cylinder 2 to respectively detect the pressure values ​​of the high-pressure steam flowing through the high-pressure pipeline 6 and the second low-pressure steam output by the high-pressure cylinder 2.

[0049] In some exemplary embodiments, referring to Figure 1-Figure 2 The turbine system also includes an exhaust cold end 7, which is connected to the low-pressure cylinder 3 and is suitable for receiving circulating exhaust steam.

[0050] It should be noted that, in this embodiment, when the steam turbine unit is running at full load, for example, when two gas turbines are running at full load, the steam turbine system is running at 100% load, and at the downstream steam inlet 31, the second low-pressure steam output by the high-pressure cylinder 2 matches the pressure and temperature of the first low-pressure steam output by the waste heat boiler 1. At this time, the upstream steam inlet 31 is closed, and all the first low-pressure steam output by the waste heat boiler 1 enters the low-pressure cylinder 3 through the branch steam path 42 connected to the downstream steam inlet 31 to expand and do work.

[0051] When the steam turbine unit is underloaded, for example, when one gas turbine is shut down and the other gas turbine is running at full load, the steam turbine system is running at 50% load, and at the upstream steam inlet 31, the second low-pressure steam outputted by the high-pressure cylinder 2 matches the pressure and temperature of the first low-pressure steam outputted by the waste heat boiler 1. At this time, the downstream steam inlet 31 is closed, and all the first low-pressure steam outputted by the waste heat boiler 1 enters the low-pressure cylinder 3 through the branch steam path 42 connected to the upstream steam inlet 31 to expand and perform work.

[0052] According to an exemplary embodiment of the present invention, please refer to Figure 1-Figure 2 , a power generation system is provided, comprising a steam turbine unit, the steam turbine system described in the above embodiment and a generator 8. The steam turbine unit comprises at least two gas turbines. The working steam of the steam turbine system is provided by a waste heat boiler 1 connected to the steam turbine unit. The generator 8 is connected to the steam turbine system, and under the action of the steam turbine system, the kinetic energy of the steam turbine unit is converted into electrical energy of the generator 8.

[0053] It should be noted that, in this embodiment, the generator 8 is connected to the rotor of the high-pressure cylinder 2 and the rotor of the low-pressure cylinder 3 of the steam turbine system through a coupling to achieve the conversion of mechanical energy into electrical energy.

[0054] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A steam turbine system, characterized in that: include: A waste heat boiler (1), wherein a heat exchanger of the waste heat boiler (1) is connected to a steam turbine unit; The high-pressure cylinder (2) is connected to the first steam outlet end (12) of the waste heat boiler (1), so that the high-pressure steam output by the waste heat boiler (1) expands inside the high-pressure cylinder (2) to perform work; and The low-pressure cylinder (3) is respectively connected to the second steam outlet end (11) of the waste heat boiler (1) and the high-pressure cylinder (2), so that the first low-pressure steam output by the waste heat boiler (1) and the second low-pressure steam output by the high-pressure cylinder (2) expand inside the low-pressure cylinder (3) to perform work; The waste heat boiler (1) is connected to the low-pressure cylinder (3) via a low-pressure pipeline (4); at least two steam inlets (31) connected to the waste heat boiler (1) are arranged at intervals along the axial direction on the low-pressure cylinder (3); the low-pressure pipeline (4) is configured to select one of the plurality of steam inlets (31) to be opened according to the pressure of the second low-pressure steam output by the high-pressure cylinder (2), so that the pressure difference between the first low-pressure steam and the steam inlet (31) in the open state is within a preset pressure difference range.

2. The steam turbine system according to claim 1, characterized in that: A plurality of blade stages (32) are arranged in sequence from upstream to downstream in the axial direction inside the low-pressure cylinder (3), and at least one blade stage (32) is spaced between two adjacent steam inlets (31); Wherein, when the steam turbine unit is operating at full load, the first low-pressure steam flows into the low-pressure cylinder (3) through the steam inlet (31) located downstream; when the steam turbine unit is operating at underload, the first low-pressure steam flows into the low-pressure cylinder (3) through the steam inlet (31) located upstream.

3. The steam turbine system according to claim 2, characterized in that: The low-pressure pipeline (4) comprises a main steam circuit (41) and at least two branch steam circuits (42), and each branch steam circuit (42) is connected to one of the steam inlets (31).

4. The steam turbine system according to any one of claims 1 to 3, characterized in that: The preset pressure difference range is 0.5-1.0ata.

5. The steam turbine system according to claim 3, characterized in that: The main steam circuit (41) is provided with a low-pressure steam inlet valve (411) to control the on-off of the main steam circuit (41); Each of the branch steam lines (42) is provided with a low-pressure regulating valve (421) to control the opening and closing of the branch steam line (42) and to regulate the flow rate of the first low-pressure steam in the branch steam line (42).

6. The steam turbine system according to claim 1, characterized in that: The high-pressure cylinder (2) is connected to the low-pressure cylinder (3) via a connecting pipeline (5).

7. The steam turbine system according to claim 1, characterized in that: The high-pressure cylinder (2) and the low-pressure cylinder (3) form a mutually connected whole.

8. The steam turbine system according to claim 1, characterized in that: The waste heat boiler (1) is connected to the high-pressure cylinder (2) via a high-pressure pipeline (6), and a high-pressure steam inlet valve (61) and a high-pressure regulating valve (62) are provided on the high-pressure pipeline (6).

9. The steam turbine system according to claim 1, characterized in that: The turbine system further comprises an exhaust steam cold end (7), wherein the exhaust steam cold end (7) is in communication with the low-pressure cylinder (3) and is suitable for receiving circulating exhaust steam.

10. A power generation system, characterized in that: include: a steam turbine unit, comprising at least two gas turbines; The steam turbine system according to any one of claims 1 to 9, wherein the working steam of the steam turbine system is provided by a waste heat boiler (1) connected to the steam turbine unit; as well as A generator (8) is connected to the steam turbine system and, under the action of the steam turbine system, converts the kinetic energy of the steam turbine unit into electrical energy of the generator (8).

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