Steam inlet structure for a steam turbine in parallel connection with a second steam source
By connecting the steam inlet structure of the second steam source in parallel in the steam turbine, and using the steam guide vanes to convert the pressure energy of the second steam source into steam kinetic energy, the problems of large throttling losses and steam flow disturbances in the existing steam turbine supplementary structure are solved, and more efficient operation and lower heat consumption are achieved.
Patent Information
- Application Number
- CN202311702077.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-12
- Publication Date
- 2025-07-01
- Estimated Expiration
- 2043-12-12
AI Technical Summary
The existing steam turbine steam replenishment structure has large throttling losses and when the steam replenishment valve is fully opened, almost all the main steam enters from the steam replenishment valve, resulting in a small flow rate after the high-pressure main steam regulating valve, which may cause blowing overheating. The steam flow disturbance caused to the turbine rotor after the steam replenishment valve is opened causes unit vibration.
The steam inlet structure of a steam turbine connected to the second steam source is adopted. By setting a steam position and a steam flow channel in the cylinder and a steam guide vanes are provided in the steam flow channel, the pressure energy of the second steam source is converted into steam kinetic energy by using the steam guide vanes to reduce the pressure loss of the second steam, and a sufficient large pressure difference is formed before and after the steam guide vanes to reduce steam flow disturbance.
Through the steam inlet structure of the second steam source connected in parallel, the steam pressure loss is reduced, the steam flow rate upstream of the steam point when the steam filling valve is fully opened is avoided, and the steam flow disturbance to the turbine rotor is reduced, and the operation efficiency and economicality of the turbine are improved.
Smart Images
Figure CN117536700B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of steam turbines, in particular to the parallel steam admission of the (ultra) high-pressure cylinder of large-capacity and high-parameter steam turbines, and also relates to the intermediate-pressure cylinder, single-cylinder steam turbines, or the steam admission structure for high-parameter steam from other steam sources incorporated into the steam turbine. Background Art
[0002] Large-capacity and high-parameter steam turbines mostly adopt full-arc admission and throttle governing design. The steam turbine design should meet the definition of four operating conditions, namely, the heat consumption acceptance condition (THA) for generating the rated power at the design back pressure, the condition (TRL) for the steam turbine to generate the nameplate power under the summer back pressure and a certain makeup water rate, the condition (TMCR) for the steam turbine to generate the maximum continuous output with the steam inlet flow rate and parameters the same as those in the TRL, and the maximum steam inlet volume of the steam turbine should meet 103% - 105% of the steam inlet volume in the TRL (VWO).
[0003] If the high-pressure steam passage area of the steam turbine is designed according to the VWO operating condition definition, in the THA operating condition, the main steam pressure is about 13% lower than the design pressure, resulting in high heat consumption during the operation of the steam turbine. In order to increase the main steam pressure during operation, generally, the areas of each stage of the high-pressure cylinder are designed according to the TMCR operating condition or the THA operating condition, and in recent years, more stage groups have selected the THA operating condition as the design point. The pressure in front of the main steam valve at the design operating condition is the design pressure. After a certain pressure stage (such as the fifth stage) in the high-pressure cylinder, a supplementary steam point is set, and additional main steam is introduced through a supplementary steam valve. When the flow rate required to enter the steam turbine during operation is greater than the design value, the supplementary steam valve is opened, so that the main steam passes through the supplementary steam valve and enters the supplementary steam position, increasing the steam inlet volume of the steam turbine to achieve the purpose of generating more electricity.
[0004] In the commonly used supplementary steam structure of the steam turbine, the steam passage after the supplementary steam valve is connected between two stages, that is, after the supplementary steam enters the moving blades of the upper stage and before the guide vanes of the lower stage. When the supplementary steam valve is opened, the steam flow rate entering the supplementary steam valve is controlled by throttling through the supplementary steam valve, and the throttling loss is relatively large.
[0005] Since the supplementary steam source comes from in front of the main steam valve, the steam entering the first stage from the main steam regulating valve needs to pass through several stages to reach the supplementary steam point. When the supplementary steam valve is opened, the pressure after the supplementary steam valve is much lower than the inlet pressure of the first stage. The flow resistance of the supplementary steam valve is small, and the flow rate passing through the supplementary steam valve is not only the inlet increment but also a large part of the diversion of the main steam regulating valve. The flow rate of the supplementary steam valve increases rapidly, and at the same time, the steam flow rate passing through the main steam regulating valve decreases. In the extreme case, if the diameter of the supplementary steam valve is large enough, when the supplementary steam valve is fully opened, almost all the main steam enters the steam turbine through the supplementary steam valve, and the stage group from behind the high-pressure main steam regulating valve to the supplementary steam point may generate overheating due to small flow rate. Generally, the flow rate entering the steam turbine through the supplementary steam valve is controlled by throttling through the supplementary steam valve. In this way, after the supplementary steam valve is opened, the pressure loss of the second steam flow is large, increasing the heat consumption of the unit.
[0006] For the supplementary steam of steam turbines with different steam sources, such as the steam from the molten salt system and the waste heat utilization steam, when the pressure of the second steam source is relatively high, there are more or less problems of large throttling losses.
[0007] How to reduce the supplementary steam pressure loss, avoid too low steam flow rate upstream of the steam collecting point when the supplementary steam valve is fully open, and solve the problem of unit vibration caused by the steam flow disturbance generated by the turbine rotor after the supplementary steam valve is opened are technical problems that need to be solved urgently by those skilled in the art. Summary of the Invention
[0008] The purpose of the present invention is to provide an inlet steam structure for a steam turbine with a parallel second steam source to solve the above technical problems.
[0009] To achieve the above purpose, the present invention provides an inlet steam structure for a steam turbine with a parallel second steam source, including a cylinder and a rotor. The cylinder is provided with a main steam inlet and a steam combining position. The main steam inlet is connected to a first steam pipeline and a first steam inlet valve. The steam combining position is connected to a second steam pipeline and a steam combining valve. Inside the cylinder, there are an upstream stage group, a pre-steam-combining guide vane, a steam collecting chamber, and a first row of moving blades after steam combining corresponding to the steam combining position. The cylinder is provided with a steam combining flow channel communicating with the steam collecting chamber at the steam combining position, and the inside of the steam combining flow channel is provided with steam combining guide vanes.
[0010] Optionally, the steam combining flow channel has an inclination angle relative to the axis direction of the steam turbine.
[0011] Optionally, the inclination angle of the steam combining flow channel with respect to the axis direction of the steam turbine is less than or equal to 50°.
[0012] Optionally, the steam combining flow channel is an annular channel in cross-section.
[0013] Optionally, a steam combining guide vane partition is provided inside the steam combining flow channel, and the steam combining guide vane partition divides the steam combining guide vanes into at least two groups of steam combining guide vane groups, and each steam combining guide vane group is respectively provided with a corresponding steam combining valve.
[0014] Optionally, the steam combining guide vanes are divided into two or four groups of steam combining guide vane groups by the steam combining guide vane partition.
[0015] Optionally, the horizontal component of the steam flow outlet angle of the steam combining guide vanes is the same as the steam flow outlet angle of the pre-steam-combining guide vanes.
[0016] Optionally, the difference between the steam flow angle after mixing of the pre-steam-combining guide vanes and the steam combining guide vanes and the geometric inlet angle of the first row of moving blades after steam combining is less than ±30°.
[0017] Optionally, the first row of moving blades after steam combining is a low reaction type blade.
[0018] Optionally, the temperature of the second steam source connected to the second steam pipe matches the steam parameters at the steam connection position of the steam turbine, and the pressure is higher than the pressure at the steam connection position of the steam turbine.
[0019] When the steam inlet structure for the parallel connection of the second steam source to the steam turbine provided by the present invention is in operation, the main steam enters the cylinder through the first steam pipe and the first steam inlet valve, and after doing work through the upstream stage group, the pre-connection guide vane, the steam collecting chamber, the first row of moving blades after connection, and the downstream stage group after connection, it is discharged from the cylinder through the exhaust passage. As supplementary second steam, it enters the steam collecting chamber from the connection steam passage through the second steam pipe and the connection valve. Since there is a connection guide vane in the connection steam passage, which has the function of converting the pressure energy of the second steam source into steam kinetic energy, the steam passing through the connection guide vane is mixed with the first steam flow after the upstream stage group and the pre-connection guide vane, and drives the downstream stage group to do work. The connection guide vane increases the pressure after the connection valve and reduces the pressure loss of the second steam flow; when the second steam source is the same as the first steam source, the decrease amplitude of the first steam flow can be reduced, and when the connection valve is fully open, there is still enough steam flowing through the upstream stage group. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 It is a system diagram of the steam turbine incorporating the second steam source;
[0021] Figure 2 It is a schematic structural diagram of the steam inlet structure for the parallel connection of the second steam source to the steam turbine provided by the embodiment of the present invention;
[0022] Figure 3 is Figure 2 The A-A view of the steam inlet structure for the parallel connection of the second steam source to the steam turbine shown.
[0023] In the figure:
[0024] 1. First steam inlet valve; 2. Cylinder; 3. Rotor; 4. Steam turbine blade passage; 5. Upstream stage group; 6. Pre-connection guide vane; 7. Steam collecting chamber; 8. First row of moving blades after connection; 9. Downstream stage group after connection; 10. Exhaust passage; 11. Connection valve; 12. Connection guide vane partition; 13. Connection guide vane group; 14. Connection guide vane; 15. Connection passage; 101. First steam pipe; 102. Second steam pipe. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0025] In order to enable those skilled in the art to better understand the solution of the present invention, the present invention will be further described in detail below with reference to the drawings and specific embodiments.
[0026] In this text, terms such as "upper, lower, inner, outer" are established based on the positional relationships shown in the drawings. Depending on the different drawings, the corresponding positional relationships may also change accordingly. Therefore, they should not be understood as absolute limitations on the scope of protection. Moreover, relational terms such as "first" and "second" are only used to distinguish one component with the same name from another, and do not necessarily require or imply any such actual relationship or order between these components.
[0027] Please refer to Figure 1 、 Figure 2 、 Figure 3 , Figure 1 is a system diagram for the steam turbine to be incorporated into the second steam source; Figure 2 is a schematic structural diagram of the steam inlet structure of the steam turbine with a parallel second steam source provided by an embodiment of the present invention; Figure 3 is Figure 2 the A-A view of the steam inlet structure of the steam turbine with a parallel second steam source shown in
[0028] As shown in the figure, in a specific embodiment, the steam inlet structure of the steam turbine with a parallel second steam source provided by the present invention mainly consists of components such as a cylinder 2, a rotor 3, a first steam pipeline 101, a first steam inlet valve 1, a second steam pipeline 102, and a parallel steam valve 11.
[0029] The cylinder 2 is provided with a main steam inlet and a parallel steam position. The main steam inlet is connected to the first steam pipeline 101 and the first steam inlet valve 1, and the parallel steam position is connected to the second steam pipeline 102 and the parallel steam valve 11. Inside the cylinder 2, there are an upstream stage group 5, a pre-parallel guide vane 6, a steam collecting chamber 7, and a first moving blade 8 after parallel steam corresponding to the parallel steam position. Moreover, the cylinder 2 is provided with a parallel steam flow channel 15 communicating with the steam collecting chamber 7 at the parallel steam position. The parallel steam flow channel 15 is an annular channel in cross-section, and parallel steam blades 14 are arranged inside the parallel steam flow channel 15.
[0030] The parallel steam flow channel 15 has a certain inclination angle with respect to the axis direction of the steam turbine, and this inclination angle should not be greater than 50°. In this way, before the second steam flow enters the first moving blade 8 after parallel steam, it has a relatively large horizontal component velocity, which is beneficial for doing work.
[0031] Considering that the second steam flow passes through the parallel steam guide vane 14 to generate a large enthalpy drop, a sufficient large pressure difference will be formed before and after the parallel steam guide vane 14. Therefore, the parallel steam guide vane 14 should have a relatively high strength.
[0032] A number of parallel steam guide vane partitions 12 are provided along the circumferential direction in the parallel steam flow path 15. In this embodiment, these parallel steam guide vane partitions 12 divide the parallel steam guide vanes 14 into four groups of parallel steam guide vane groups 13, and each parallel steam guide vane group 13 is respectively provided with a corresponding parallel steam valve 11. That is to say, a total of four parallel steam valves 11 are provided. The opening sequence of the parallel steam valves 11 corresponding to the four groups of parallel steam guide vane groups 13 has an on-site combination function, and the opening sequence can be adjusted according to the on-site shafting vibration and bearing temperature conditions.
[0033] Of course, in other embodiments, the parallel steam guide vane partitions 12 can also divide the parallel steam guide vanes 14 into two groups or six groups of parallel steam guide vane groups 13, and correspondingly two or six parallel steam valves 11 are provided. It is advisable that the number of guide vane groups be an even number to avoid asymmetric disturbance of the rotor by the second steam flow.
[0034] The horizontal component of the steam flow outlet angle of the parallel steam guide vanes 14 is consistent with the steam flow outlet angle of the pre-parallel steam guide vanes 6, so that the difference between the mixed steam flow angle and the geometric inlet angle of the first row of moving blades 8 after parallel steam admission meets the design requirements. For example, the difference between the two is not more than ±30°. Moreover, the first row of moving blades 8 after parallel steam admission can be designed as low-reaction blades, taking into account the operating characteristics of both the case of only the first steam flow and the case of parallel steam admission.
[0035] The second steam source for parallel steam admission can be the same as the first steam source or other high-pressure steam sources. The temperature of the steam source should match the steam parameters at the parallel steam admission position of the steam turbine, and the pressure of the second steam source should be higher than the pressure at the parallel steam admission position of the steam turbine.
[0036] For large-capacity units using parallel steam valves 11, both the second steam source and the first steam source in front of the parallel steam valves 11 come from the boiler. The areas of each stage in the steam turbine cylinder 2 are designed according to a value less than the maximum evaporation capacity of the boiler. When the steam flow rate through the cylinder is greater than the designed flow rate, the pressure in front of the first steam inlet valve 1 exceeds the designed pressure. To further increase the steam admission volume of the steam turbine and make full use of the maximum evaporation capacity of the boiler, the parallel steam valve 11 is opened, and the second steam flow enters the downstream stage group 9 from the parallel steam admission position of the steam turbine and does work together with the steam flow passing through the upstream stage group 5 to achieve the purpose of increasing power.
[0037] The above embodiments are only the preferred solutions of the present invention, and are not specifically limited thereto. On this basis, targeted adjustments can be made according to actual needs to obtain different implementation manners. For example, the parallel steam guide vanes 14 can also not be partitioned, and the parallel steam flow path 15 forms an integral annular channel. Or, the number of parallel steam guide vanes 14 in the parallel steam guide vane group 13 can be equal, or different blade numbers can be selected according to the flow characteristics requirements, and so on. Since there are many possible implementation ways, they will not be exemplified one by one here.
[0038] The steam inlet structure for the parallel second steam source is used to incorporate a second high-pressure steam on the basis of the first high-pressure steam. The second high-pressure steam enters between the guide vane and the moving blade at a suitable position of the steam turbine through the steam combining valve 11, the steam combining flow channel 15, and the steam combining guide vane group 14, and converges with the first steam from the boiler passing through the first steam inlet valve 1 and the upstream stage group 5 to drive the steam turbine to do work and increase the output of the steam turbine generator set. Moreover, when the steam combining valve is opened, the influence on the first steam can be reduced, and the pressure difference between the initial pressure of the second steam and the steam pressure at the steam collecting point is converted into the steam flow velocity through the steam combining guide vane, directly impelling the moving blade after steam combination, reducing the pressure loss of the second supplementary steam, thereby improving the economy of the steam turbine.
[0039] The present invention is particularly applicable to the high-pressure steam collection of steam turbines, and is also applicable to the incorporation of other high-pressure and high-temperature steam sources into steam turbines, such as the ultra-high-pressure cylinder of secondary reheat and the high-pressure cylinder of primary reheat, and is also applicable to the steam combination of the intermediate-pressure cylinder.
[0040] The above has introduced in detail the steam inlet structure for the parallel second steam source of the steam turbine provided by the present invention. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the core idea of the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.
Claims
1. The steam inlet structure for a steam turbine in parallel connection with a second steam source, comprising a cylinder (2) and a rotor (3), wherein the cylinder (2) is provided with a main steam inlet and a steam parallel connection position, the main steam inlet is connected to a first steam pipeline (101) and a first steam inlet valve (1), the steam parallel connection position is connected to a second steam pipeline (102) and a steam parallel connection valve (11), and inside the cylinder (2), there are provided an upstream stage group (5), a pre-steam-parallel guide vane (6), a steam collecting cavity (7) and a first row of moving blades (8) after steam parallel connection corresponding to the steam parallel connection position, characterized in that, The cylinder (2) is provided with a steam combining flow channel (15) communicating with the steam collecting chamber (7) at the steam combining position, and a steam combining guide vane (14) is arranged inside the steam combining flow channel (15); the steam combining flow channel (15) is an annular channel in cross section, a steam combining guide vane partition plate (12) is arranged in the steam combining flow channel (15), and the steam combining guide vane partition plate (12) divides the steam combining guide vane (14) into at least two groups of steam combining guide vane groups (13), and each steam combining guide vane group (13) is respectively provided with a corresponding steam combining valve (11); the horizontal component of the steam flow outlet angle of the steam combining guide vane (14) is consistent with the steam flow outlet angle of the pre-steam-combining guide vane (6), and the range of the difference between the steam flow angle after mixing of the pre-steam-combining guide vane (6) and the steam combining guide vane (14) and the geometric inlet angle of the first row of moving blades (8) after steam combining is ±30°.
2. The steam inlet structure of the second steam source in parallel with the steam turbine according to claim 1, wherein The steam combining flow channel (15) has an inclination angle relative to the axis direction of the steam turbine.
3. The steam inlet structure of the second steam source in parallel with the steam turbine according to claim 2, characterized in that, The inclination angle of the steam combining flow channel (15) relative to the axis direction of the steam turbine is less than or equal to 50°.
4. The steam inlet structure of the second steam source in parallel connection with the steam turbine according to claim 1, characterized in that, The steam combining guide vane (14) is divided into two groups, three groups, four groups or five groups of steam combining guide vane groups (13) by the steam combining guide vane partition plate (12).
5. The steam inlet structure of the second steam source in parallel with the steam turbine according to claim 1, characterized in that, The first row of moving blades (8) after steam combining are low reaction blades.
6. The steam inlet structure of the second steam source in parallel connection with the steam turbine according to any one of claims 1 to 5, characterized in that The temperature of the second steam source connected by the second steam pipeline (102) matches the steam parameters at the steam combining position of the steam turbine, and the pressure is higher than the pressure at the steam combining position of the steam turbine.
Citation Information
Patent Citations
Steam compensating turbine
CN101886556A
Steam supplementing chamber structure of steam turbine cylinder
CN112832875A