Sliding pressure operation method of nuclear power plant steam turbine

Abstract

This invention discloses a sliding pressure operation method for a nuclear power plant turbine. The method includes the following steps: determining the flow area of ​​the first-stage diaphragm of the high-pressure cylinder of the turbine; determining the turbine power based on the flow area of ​​the first-stage diaphragm, and determining the corresponding nuclear reactor power based on the turbine power-reactor power correspondence; starting the turbine, maximizing the opening of the turbine's inlet regulating valve, and adjusting the nuclear reactor power to gradually adjust the turbine power to the target value. This sliding pressure operation method maximizes the opening of the turbine's inlet regulating valve, reducing throttling losses, improving turbine unit efficiency, increasing turbine work capacity, and conserving nuclear fuel required for nuclear power plant operation. By rematching the correspondence between reactor power and turbine power, and ensuring the rapid response of the inlet regulating valve under special transient conditions, the stability and safety of the nuclear power plant operation are maintained.

Description

Technical Field

[0001] This invention relates to the field of nuclear power plant operation technology, and in particular to a method for sliding pressure operation of a nuclear power plant steam turbine. Background Technology

[0002] Sliding pressure operation refers to the operation of a steam turbine under different operating conditions, in which not only the main steam valve is fully open, but also the speed regulating valve is fully open. In this case, the change in steam turbine power is achieved by changing the pressure and temperature of the main steam in front of the steam turbine.

[0003] Currently, most nuclear power plant turbines operate at constant pressure. Load reduction is achieved by closing the turbine's inlet steam regulating valve. 100% reactor power control is achieved through the combined action of the inlet steam regulating valve and the first-stage diaphragm. Partial reactor power control is achieved by closing the inlet steam regulating valve. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for sliding pressure operation of a nuclear power plant steam turbine.

[0005] The technical solution adopted by this invention to solve its technical problem is: to construct a method for sliding pressure operation of a nuclear power plant steam turbine, comprising the following steps:

[0006] Determine the flow area of ​​the first-stage diaphragm in the high-pressure cylinder of the steam turbine;

[0007] The turbine power is determined based on the flow area of ​​the first stage diaphragm of the high-pressure cylinder, and the nuclear reactor power corresponding to the turbine power is determined based on the correspondence between the turbine power and the nuclear reactor power.

[0008] Start the steam turbine, bring the steam inlet regulating valve of the steam turbine to its maximum opening, and adjust the power of the nuclear reactor to gradually adjust the power of the steam turbine to the target value.

[0009] Preferably, in the nuclear power plant turbine sliding pressure operation method constructed by the present invention, the step of determining the flow area of ​​the first-stage diaphragm of the high-pressure cylinder of the turbine includes:

[0010] The turbine nozzle outlet angle is corrected according to the nozzle outlet angle correction formula, and the flow area of ​​the first-stage diaphragm of the high-pressure cylinder of the turbine is determined according to the diaphragm flow area formula.

[0011] Preferably, in the nuclear power plant turbine sliding pressure operation method constructed by the present invention, the nozzle steam outlet angle correction formula is as follows:

[0012]

[0013] Where α is the turbine nozzle outlet angle, o is the turbine nozzle throat width, t is the turbine nozzle pitch, and δ is the corrected outlet deflection angle.

[0014] Preferably, in the nuclear power plant turbine sliding pressure operation method constructed by the present invention, the formula for the flow area of ​​the diaphragm is:

[0015]

[0016] Where A is the flow area of ​​the first stage diaphragm of the high-pressure cylinder of the steam turbine, Z is the number of steam passages of the steam turbine, t is the nozzle pitch of the steam turbine, l is the nozzle height of the steam turbine, and α is the steam outlet angle of the steam turbine nozzle.

[0017] Preferably, in the nuclear power plant turbine sliding pressure operation method constructed by the present invention, the step of determining the turbine power based on the flow area of ​​the first-stage diaphragm of the high-pressure cylinder includes:

[0018] The first-stage inlet pressure of the steam turbine is determined based on the flow area of ​​the first-stage diaphragm of the high-pressure cylinder, and the power of the steam turbine is determined by the formula for the first-stage inlet pressure, using the first-stage inlet pressure as a reference.

[0019] Preferably, in the nuclear power plant turbine sliding pressure operation method constructed by the present invention, the inlet steam pressure formula is:

[0020]

[0021] Where P is the first-stage inlet steam pressure of the steam turbine, and We is the steam turbine power.

[0022] Preferably, in the nuclear power plant turbine sliding pressure operation method constructed by the present invention, the formula expressing the correspondence between turbine power and nuclear reactor power is as follows:

[0023]

[0024] Where We is the turbine power and Wt is the nuclear reactor power of the turbine.

[0025] Preferably, in the nuclear power plant turbine sliding pressure operation method constructed by the present invention, the step of adjusting the nuclear reactor power includes:

[0026] The power of the nuclear reactor is adjusted by regulating the position of the nuclear reactor control rods and the boron concentration of the nuclear reactor, thereby controlling the magnitude of the first-stage inlet steam pressure entering the turbine. At this time, the inlet steam regulating valve is kept at its maximum opening.

[0027] Preferably, the nuclear power plant turbine sliding pressure operation method constructed in this invention further includes the following steps:

[0028] During the transient operation of the steam turbine unit when the load is rapidly reduced, the steam inlet regulating valve is quickly closed to reduce the power of the steam turbine and maintain the stability of the unit.

[0029] By implementing this invention, the following beneficial effects are achieved:

[0030] The present invention provides a sliding pressure operation method for a nuclear power plant turbine, comprising the following steps: determining the flow area of ​​the first-stage diaphragm of the high-pressure cylinder of the turbine; determining the turbine power based on the flow area of ​​the first-stage diaphragm of the high-pressure cylinder, and determining the corresponding nuclear reactor power based on the turbine power-nuclear reactor power correspondence; starting the turbine, maximizing the opening of the turbine's inlet regulating valve, and adjusting the nuclear reactor power to gradually adjust the turbine power to the target value. This sliding pressure operation method maximizes the opening of the turbine's inlet regulating valve, reducing throttling losses, improving turbine unit efficiency, increasing turbine work capacity, and conserving nuclear fuel required for nuclear power plant operation. By rematching the correspondence between reactor power and turbine power, and ensuring the rapid response of the inlet regulating valve under special transient conditions, the stability and safety of the nuclear power plant operation are maintained. Attached Figure Description

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0032] Figure 1 This is a flowchart of the sliding pressure operation method for a nuclear power plant steam turbine according to the present invention;

[0033] Figure 2 This is a pressure-load correspondence curve of the sliding pressure operation method of the nuclear power plant steam turbine of the present invention;

[0034] Figure 3 This is a schematic diagram showing the connection relationship between the steam inlet regulating valve and the first-stage diaphragm of the high-pressure cylinder in the sliding pressure operation method of the nuclear power plant steam turbine of the present invention. Detailed Implementation

[0035] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0036] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0037] See Figure 1 The first embodiment of the present invention discloses a method for sliding pressure operation of a nuclear power plant steam turbine, the method comprising the following steps:

[0038] S1. Determine the flow area of ​​the first-stage diaphragm of the high-pressure cylinder of the steam turbine.

[0039] In this step, since the first-stage inlet steam pressure of the turbine is originally determined by the first-stage diaphragm of the high-pressure cylinder and the inlet steam regulating valve, the flow area of ​​the first-stage diaphragm of the high-pressure cylinder needs to be precisely designed to ensure that it fully opens in coordination with the subsequent turbine inlet steam regulating valve. Therefore, step S1 includes the following steps S101 and S102:

[0040] Step S101: Correct the turbine nozzle steam outlet angle according to the nozzle steam outlet angle correction formula; the nozzle steam outlet angle correction formula is: Where α is the turbine nozzle outlet angle, o is the turbine nozzle throat width, t is the turbine nozzle pitch, and δ is the corrected outlet deflection angle.

[0041] Step S102: Determine the flow area of ​​the first-stage diaphragm in the high-pressure cylinder of the steam turbine according to the diaphragm flow area formula; the diaphragm flow area formula is: Where A is the flow area of ​​the first stage diaphragm of the high-pressure cylinder of the steam turbine, Z is the number of steam passages of the steam turbine, t is the nozzle pitch of the steam turbine, l is the nozzle height of the steam turbine, and α is the steam outlet angle of the steam turbine nozzle.

[0042] Steps S101 and S102 further optimize the flow area of ​​the first diaphragm in the high-pressure cylinder of the steam turbine and the steam flow rate in the first stage of the high-pressure cylinder, ensuring the safe passage of steam through the nuclear island and achieving 100% reactor power with the regulating valve fully open. In other embodiments, due to the increased pressure difference upstream and downstream of the diaphragm, the strength of each stage of the high-pressure cylinder and the enthalpy drop distribution of each stage are also calculated and modified for matching.

[0043] Step S2: Determine the turbine power based on the flow area of ​​the first stage diaphragm of the high-pressure cylinder, and determine the corresponding nuclear reactor power based on the correspondence between turbine power and nuclear reactor power.

[0044] In this step, the first-stage inlet steam pressure of the turbine is determined based on the flow area of ​​the first-stage diaphragm. Then, using this first-stage inlet steam pressure as a reference, the turbine power is determined through the inlet steam pressure formula. (See also...) Figure 2 The pressure-load curve shown reflects the relationship between inlet steam pressure and turbine power. The formula for inlet steam pressure is: Where P is the first-stage inlet steam pressure of the steam turbine, and We is the steam turbine power. The formula expressing the relationship between steam turbine power and nuclear reactor power is: Where We represents the turbine power and Wt represents the nuclear reactor power of the turbine. This step ensures that the nuclear reactor power and turbine power are matched during sliding pressure operation of the nuclear power plant turbine, allowing for stable and accurate matching and adjustment of the turbine's operating status.

[0045] Step S3: Start the steam turbine, make the steam inlet regulating valve of the steam turbine reach the maximum opening, and adjust the nuclear reactor power to gradually adjust the steam turbine power to the target value.

[0046] In this step, the nuclear reactor power is adjusted by regulating the position of the reactor control rods and the reactor boron concentration, with the steam inlet regulating valve opening at 100%. The relationship between nuclear reactor power and turbine power is referenced in the aforementioned turbine power-nuclear reactor power correspondence. In some other embodiments, the opening of the steam inlet regulating valve is fixed at a specific value between 40% and 100%. For example, taking a 45% opening of the steam inlet regulating valve as an example, see [link to relevant documentation]. Figure 3 With the current design reactor outlet steam header pressure remaining unchanged, taking 66.3 Bar as an example, practice has shown that when the flow area of ​​the first stage diaphragm is reduced from 0.11 square meters to 0.1 square meters, and the opening of the steam inlet regulating valve is increased from 35% to 45%, the throttling loss at the regulating valve is reduced. This part of the energy can be used to do work, improve efficiency, and increase the turbine inlet steam pressure to 61 bar.

[0047] Furthermore, to improve the safety and stability of the sliding pressure operation of the nuclear power plant turbine, taking the turbine inlet regulating valve starting to close rapidly from about 40% opening during load shedding of the original unit as an example, compared with constant pressure operation, the stroke required for the inlet regulating valve to close from 100% opening is longer during the sliding pressure operation of the turbine. Therefore, the sliding pressure operation method of the nuclear power plant turbine in this embodiment also includes:

[0048] Step S4: Under the transient condition of rapid load reduction of the steam turbine unit, the steam inlet regulating valve is quickly closed to reduce the steam turbine power and maintain the stability of the unit.

[0049] In the sliding pressure operation method of a nuclear power plant steam turbine disclosed in this invention, except for special transient conditions, the steam turbine's inlet regulating valves are fully open, meaning all unit inlet regulating valves are open and maintained at 100%. Therefore, the first-stage inlet steam pressure of the steam turbine depends only on the pre-set flow area of ​​the first-stage diaphragm of the high-pressure cylinder. Compared to traditional constant pressure operation, the throttling loss at 100% opening of the inlet regulating valves is very small, and a smaller flow area of ​​the first-stage diaphragm of the high-pressure cylinder can achieve a higher first-stage inlet steam pressure than before. During transient conditions of rapid load reduction in the steam turbine unit, the inlet regulating valves are quickly closed to reduce turbine power and maintain unit stability.

[0050] By implementing this invention, the following beneficial effects are achieved:

[0051] The present invention provides a sliding pressure operation method for a nuclear power plant turbine, comprising the following steps: determining the flow area of ​​the first-stage diaphragm of the high-pressure cylinder of the turbine; determining the turbine power based on the flow area of ​​the first-stage diaphragm of the high-pressure cylinder, and determining the corresponding nuclear reactor power based on the turbine power-nuclear reactor power correspondence; starting the turbine, maximizing the opening of the turbine's inlet regulating valve, and adjusting the nuclear reactor power to gradually adjust the turbine power to the target value. This sliding pressure operation method maximizes the opening of the turbine's inlet regulating valve, reducing throttling losses, improving turbine unit efficiency, increasing turbine work capacity, and conserving nuclear fuel required for nuclear power plant operation. By rematching the correspondence between reactor power and turbine power, and ensuring the rapid response of the inlet regulating valve under special transient conditions, the stability and safety of the nuclear power plant operation are maintained.

[0052] It is understood that the above embodiments only illustrate preferred embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that for those skilled in the art, the above embodiments or technical features can be freely combined, and several modifications and improvements can be made without departing from the concept of the present invention. These all fall within the protection scope of the present invention. That is, the embodiments described "in some embodiments" can be freely combined with any of the embodiments above and below. Therefore, all equivalent transformations and modifications made within the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A method for sliding pressure operation of a nuclear power plant steam turbine, characterized in that, Includes the following steps: Determine the flow area of ​​the first-stage diaphragm in the high-pressure cylinder of the steam turbine; The turbine power is determined based on the flow area of ​​the first stage diaphragm of the high-pressure cylinder, and the nuclear reactor power corresponding to the turbine power is determined based on the correspondence between the turbine power and the nuclear reactor power. Start the steam turbine, bring the steam inlet regulating valve of the steam turbine to its maximum opening, and adjust the power of the nuclear reactor to gradually adjust the power of the steam turbine to the target value; The step of determining the turbine power based on the flow area of ​​the first-stage diaphragm of the high-pressure cylinder includes: The first-stage inlet pressure of the steam turbine is determined based on the flow area of ​​the first-stage diaphragm of the high-pressure cylinder, and the power of the steam turbine is determined by the formula of the first-stage inlet pressure, using the first-stage inlet pressure as a reference. The formula for the first stage inlet steam pressure is: Where P is the first-stage inlet steam pressure of the steam turbine, and We is the steam turbine power.

2. The method for sliding pressure operation of a nuclear power plant steam turbine according to claim 1, characterized in that, The step of determining the flow area of ​​the first-stage diaphragm of the high-pressure cylinder of the steam turbine includes: The turbine nozzle outlet angle is corrected according to the nozzle outlet angle correction formula, and the flow area of ​​the first-stage diaphragm of the high-pressure cylinder of the turbine is determined according to the diaphragm flow area formula.

3. The method for sliding pressure operation of a nuclear power plant steam turbine according to claim 2, characterized in that, The nozzle outlet steam angle correction formula is: Where α is the turbine nozzle outlet angle, o is the turbine nozzle throat width, t is the turbine nozzle pitch, and δ is the corrected outlet deflection angle.

4. The method for sliding pressure operation of a nuclear power plant steam turbine according to claim 2, characterized in that, The formula for the flow area of ​​the partition is: Where A is the flow area of ​​the first stage diaphragm of the high-pressure cylinder of the steam turbine, Z is the number of steam passages of the steam turbine, t is the nozzle pitch of the steam turbine, l is the nozzle height of the steam turbine, and α is the steam outlet angle of the steam turbine nozzle.

5. The method for sliding pressure operation of a nuclear power plant turbine according to claim 1, characterized in that, The formula for expressing the correspondence between turbine power and nuclear reactor power is as follows: Where We is the turbine power and Wt is the nuclear reactor power of the turbine.

6. The method for sliding pressure operation of a nuclear power plant turbine according to claim 1, characterized in that, The step of adjusting the power of the nuclear reactor includes: The power of the nuclear reactor is adjusted by regulating the position of the nuclear reactor control rods and the boron concentration of the nuclear reactor, thereby controlling the magnitude of the first-stage inlet steam pressure entering the turbine. At this time, the inlet steam regulating valve is kept at its maximum opening.

7. The method for sliding pressure operation of a nuclear power plant steam turbine according to claim 1, characterized in that, It also includes the following steps: During the transient operation of the steam turbine unit when the load is rapidly reduced, the steam inlet regulating valve is quickly closed to reduce the power of the steam turbine and maintain the stability of the unit.

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