CN112127957B - Method for measuring main steam flow of steam turbine of thermal power plant - Google Patents
Method for measuring main steam flow of steam turbine of thermal power plant Download PDFInfo
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- CN112127957B CN112127957B CN202010777986.9A CN202010777986A CN112127957B CN 112127957 B CN112127957 B CN 112127957B CN 202010777986 A CN202010777986 A CN 202010777986A CN 112127957 B CN112127957 B CN 112127957B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D21/00—Shutting-down of machines or engines, e.g. in emergency; Regulating, controlling, or safety means not otherwise provided for
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D21/00—Shutting-down of machines or engines, e.g. in emergency; Regulating, controlling, or safety means not otherwise provided for
- F01D21/003—Arrangements for testing or measuring
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Abstract
The invention provides a main steam flow of a steam turbine of a thermal power plantThe measuring method comprises the following steps of taking the whole pressure level of a high-pressure cylinder as a primary group, and leading out a main steam flow calculation formula by a Friedel's formula, wherein the main steam flow calculation formula specifically comprises the following steps:
wherein G is r -flow under variable conditions; g 0 -flow under design conditions; t is 0 、P 1 -the absolute temperature and pressure of the main steam under design conditions; t is 0r 、P 1r -main steam absolute temperature and pressure under varying conditions; p 2 -high pressure cylinder exhaust pressure at design conditions; p 2r And the exhaust pressure of the high-pressure cylinder under the variable working condition. The method for measuring the main steam flow of the steam turbine of the thermal power plant avoids various factors influencing the temperature or the pressure of the regulating stage in the actual operation process, improves the accuracy of the main steam flow measurement, and has important significance for calculating and analyzing the economical efficiency of a thermodynamic system.
Description
Technical Field
The invention belongs to the technical field of main steam flow measurement of turbines, and particularly relates to a method for measuring main steam flow of a turbine of a thermal power plant.
Background
The main steam flow is one of key parameters of the generator set, and accurate measurement of the main steam flow is of great importance to online performance monitoring, process control and operation optimization of the generator set. Although the flowmeter is used for measuring the main steam flow, the flowmeter is simple and convenient to operate, the pressure loss caused by the flowmeter can increase the heat consumption of the unit, and particularly for the unit with high parameters and large capacity, the pressure loss is not negligible. Moreover, when the unit is subjected to a large range of variable loads, the measurement accuracy of the flowmeter is not ideal. At present, when a generating set is designed, a main steam flow measuring point is cancelled. In this case, the main steam flow is calculated by using the relevant parameters, and the theoretical basis is the well-known foley formula:
in the formula: g r -flow under variable conditions; g 0 -flow under design conditions; t is 0 、P 0 -nominal high pressure regulating stage steam absolute temperature and pressure; t is 0r 、P 0r -high pressure regulation stage steam absolute temperature and pressure under variable conditions; p 4 -a nominal high discharge pressure; p 4r -high discharge pressure under variable conditions.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a method for measuring the main steam flow of a steam turbine of a thermal power plant.
The invention is realized by the following steps:
the invention provides a method for measuring main steam flow of a steam turbine of a thermal power plant, which takes the whole pressure level of a high-pressure cylinder as a primary group, and introduces a formula for calculating the main steam flow by a Friedel-crafts formula, and specifically comprises the following steps:
wherein G is r -flow under variable conditions; g 0 -flow under design conditions; t is 0 、P 1 -the absolute temperature and pressure of the main steam under design conditions; t is 0r 、P 1r -main steam absolute temperature and pressure under varying conditions; p 2 -high pressure cylinder exhaust pressure at design conditions; p 2r And the exhaust pressure of the high-pressure cylinder under the variable working condition.
Furthermore, considering the switching working condition of the high-pressure heater, the correction coefficient k is added to further perfect the calculation formula,
further, the correction coefficient k only refers to the switching and cutting conditions of the first-stage high-pressure heater.
Further, when the high pressure heater is turned on, k =0; when the high-pressure heater is not put into the steam turbine, k is tested out by comparing the main steam flow of the working condition of the THA of the steam turbine.
Furthermore, after partial work of the steam is performed in a plurality of stages of the high-pressure cylinder of the steam turbine, the steam is completely led into the high-pressure heater to be heated again and enters the boiler, when the superheat degree is improved, the steam is sent back to the intermediate-pressure cylinder and the rest stages of the low-pressure cylinder to continue to expand and perform work, the exhaust steam is finally discharged into the condenser and the low-pressure heater connected with the condenser, and the exhaust steam is heated by the low-pressure heater and then sent into the deaerator.
Further, T 0r 、P 1r And P 2r Are all obtained by direct measurement techniques.
The invention has the following beneficial effects:
1. by introducing the formula (2) or (3), various factors influencing the temperature or pressure of the regulating stage in the actual operation process are avoided, the accuracy of the main steam flow measurement is improved, and the method has important significance for the economic calculation and analysis of the thermodynamic system.
2. The accurate measurement has a vital significance on online performance monitoring, process control and operation optimization of the unit, and the main steam flow measured by the method is high in accuracy.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic diagram of a reheating unit thermodynamic system in an embodiment of the invention.
In the figure: 1-a high pressure cylinder; 2-intermediate pressure cylinder; 3-low pressure cylinder; 4-a boiler; 5-a high pressure heater; 6-low pressure heater; 7-a deaerator; 8-a gas condenser.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The embodiment of the invention provides a method for measuring main steam flow of a steam turbine of a thermal power plant, which takes the whole pressure level of a high-pressure cylinder as a primary group, and introduces a formula for calculating the main steam flow by using a Friedel formula, and specifically comprises the following steps:
wherein G is r -flow under variable conditions; g 0 -flow under design conditions; t is 0 、P 1 -the absolute temperature and pressure of the main steam under design conditions; t is a unit of 0r 、P 1r -main steam absolute temperature and pressure under varying conditions; p 2 -high pressure cylinder exhaust pressure at design conditions; p 2r And the exhaust pressure of the high-pressure cylinder under the variable working condition.
Since the main steam flow is calculated using equation (1), there are generally many factors that affect:
(1) influence of change in flow area
When the sequential valve control mode is adopted, if the working condition changes within the range of one hundred percent to fifty percent, the partial steam admission degree of the regulating stage can change along with the change of the number of the valves participating in the control regulation, and the through-flow degrees of the first pressure stages after the regulating stage can be changed, namely the individual steam through-flow areas in the several stage groups selected by us are changed. Meanwhile, when the unit runs for a long time, the flow area is scaled and reduced, so that the actual steam pressure value before the stage group under the same condition is increased, the calculation result is higher than the actual value, and the calculation accuracy is affected.
(2) Influence of reheat desuperheating Water
The reheater pressure will be reduced because of the addition of the reheat desuperheated water. Moreover, these flows are all injected into the medium and low pressure cylinders, which changes the pressure drop value of the medium and low pressure cylinders, and these additional factors cause the actual steam pressure value before the stage group to become higher, which results in the displayed value of the main steam flow measurement to become higher.
(3) Influence of heater throw-in and cut-off
Because the steam turbine stage group is switched under certain conditions, the change of the steam extraction amount can affect the pressure in front of the steam turbine stage group, and particularly after the heater of the high-pressure cylinder is cut off, the steam extraction amount in the front section of the high-pressure cylinder can be obviously reduced, so that under the same main steam flow, the pressure in front of the steam turbine stage group can be increased, and the calculation result of the main steam flow is high.
In order to avoid the above-mentioned influence factors, when formula (1) is applied and only the high pressure cylinder is measured, it can be seen from fig. 1 that if the operation mode of the high pressure heater is not changed for the high pressure cylinder, the whole pressure level of the high pressure cylinder is regarded as a primary group, and only P is considered 1 、P 2 The application condition of the Friedel formula can be met, so that the formula (2) is led out, and the Friedel formula can also be applied in the dynamic state because the volume of the circulation part of the high-pressure cylinder is small and the response is quick in the variable working condition.
If the formula (2) adds the correction coefficient k to consider the switching working condition of the high-pressure heater, the main steam flow is as shown in the formula (3):
usually, the high-pressure cylinder only has one-stage steam extraction, and the correction coefficient k in the formula (3) only refers to the cutting and feeding of the one-stage high-pressure heater. Zero when the high pressure heater is put in; when the high-pressure heater is not put into the steam turbine, the main steam flow of the working condition THA of the steam turbine is compared to test out.
Referring to fig. 1, after a part of work is done by steam in a plurality of stages of a high-pressure cylinder of the steam turbine, the steam is completely led into a high-pressure heater to be heated again and enters a boiler, when the superheat degree is improved, the steam is sent back to the intermediate-pressure cylinder and the rest stages of the low-pressure cylinder to continue to expand and do work, the exhaust steam is finally discharged into a condenser and a low-pressure heater connected with the condenser, and the exhaust steam is heated by the low-pressure heater and then sent into a deaerator.
In the formula, T 0r 、P 1r And P 2r All are obtained by a direct measurement technology, in the embodiment, corresponding measuring equipment can be arranged at the rear part of a high-pressure cylinder regulating stage blade and the steam outlet to measure T 0r 、P 1r And P 2r Then G can be calculated by the formula (2) or (3) r By adopting the method, various factors influencing the temperature or pressure of the regulating stage in the actual operation process are avoided, the accuracy of the main steam flow measurement is improved, and the method has important significance for calculating and analyzing the economical efficiency of the thermodynamic system.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (5)
1. The method for measuring the main steam flow of the steam turbine of the thermal power plant is characterized in that the whole pressure level of a high-pressure cylinder is taken as a primary group, and a formula for calculating the main steam flow is introduced by a Friedel formula, and the method specifically comprises the following steps:
wherein G is r -flow under variable conditions; g 0 -flow under design conditions; t is 0 、P 1 -the absolute temperature and pressure of the main steam under design conditions; t is 0r 、P 1r -main steam absolute temperature and pressure at varying conditions; p 2 -high pressure cylinder exhaust pressure at design conditions; p 2r And the exhaust pressure of the high-pressure cylinder under the variable working condition.
2. The method for measuring the main steam flow of the steam turbine of the thermal power plant according to claim 1, characterized in that: considering the working conditions of switching and cutting of the high-pressure heater, the correction coefficient k is increased to further perfect the calculation formula,
when the high pressure heater is put in, k =0; when the high-pressure heater is not put into the steam turbine, k is tested out by comparing the main steam flow of the working condition of the THA of the steam turbine.
3. The method for measuring the main steam flow of the steam turbine of the thermal power plant according to claim 2, characterized in that: the correction coefficient k only refers to the switching and cutting conditions of the first-stage high-pressure heater.
4. The method for measuring the main steam flow of the steam turbine of the thermal power plant according to claim 2 or 3, characterized in that: after the steam performs a part of work in a plurality of stages of the high-pressure cylinder of the steam turbine, the steam is completely led into the high-pressure heater to be heated again and enters the boiler, after the superheat degree is improved, the steam is sent back to the middle-pressure cylinder and the other stages of the low-pressure cylinder to continue to expand and do work, the exhaust steam is finally discharged into the condenser and the low-pressure heater connected with the condenser, and the exhaust steam is heated by the low-pressure heater and then sent into the deaerator.
5. The method for measuring the main steam flow of the steam turbine of the thermal power plant according to claim 2, characterized in that: t is a unit of 0r 、P 1r And P 2r Are all obtained by direct measurement techniques.
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| CN113566186B (en) * | 2021-07-28 | 2023-08-29 | 西安热工研究院有限公司 | Boiler drum water level adjusting method after damaged stage pressure measuring points |
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| CN106354999A (en) * | 2016-08-25 | 2017-01-25 | 哈尔滨工业大学 | On-line diagnosis method for load oscillation and sudden load change of thermal power unit |
| CN110206595A (en) * | 2019-03-26 | 2019-09-06 | 云南华电镇雄发电有限公司 | A kind of Steam Turbine operation heat consumption rate on air real time test method and device |
| CN110702175A (en) * | 2019-09-11 | 2020-01-17 | 湖南大唐先一科技有限公司 | Online soft measurement device and method for main steam flow of steam turbine of thermal power plant |
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Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102073773A (en) * | 2011-01-18 | 2011-05-25 | 王卫良 | Main steam pressure tracking optimization method for steam turbine |
| CN104330260A (en) * | 2014-10-17 | 2015-02-04 | 哈尔滨工业大学 | Turbine sequence valve load abrupt fault diagnosis method based on high control valve switch test |
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| CN106354999A (en) * | 2016-08-25 | 2017-01-25 | 哈尔滨工业大学 | On-line diagnosis method for load oscillation and sudden load change of thermal power unit |
| CN110206595A (en) * | 2019-03-26 | 2019-09-06 | 云南华电镇雄发电有限公司 | A kind of Steam Turbine operation heat consumption rate on air real time test method and device |
| CN110702175A (en) * | 2019-09-11 | 2020-01-17 | 湖南大唐先一科技有限公司 | Online soft measurement device and method for main steam flow of steam turbine of thermal power plant |
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