CN114817835B - Real-time calculation method for three-level overrun safety risk of main steam pipeline pressure - Google Patents

Abstract

The invention discloses a real-time calculation method of a three-level overrun safety risk of main steam pipeline pressure, which comprises the following steps: according to the previous time t of each main steam pressure measuring point _i‑1 Is the kth stage overpressure state S _Bk (t _i‑1 ) Each main steam pressure measuring point is at the current time t _i Is the kth stage overpressure state S _Bk (t _i ) Judging whether the k-th overpressure occurs or not; when the kth level overpressure occurs, calculating the current time t according to the time when the kth level overpressure occurs _i Real-time overpressure safety risk value R of each main steam pressure measuring point _jk (t _i ) The method comprises the steps of carrying out a first treatment on the surface of the According to the current time t _i Real-time overpressure safety risk value R of each main steam pressure measuring point _jk (t _i ) Calculating an accumulated overpressure safety risk value R from each main steam pressure measuring point to the moment of calculation _j The method comprises the steps of carrying out a first treatment on the surface of the Based on the accumulated overpressure safety risk value R from each main steam pressure measuring point to the moment of calculation _j The method calculates the accumulated overpressure safety risk value R of the main steam pipeline until the calculation time, and calculates the three-level overrun safety risk of the pressure of the main steam pipeline in real time.

Description

A real-time calculation method for the safety risk of three-level over-limit pressure in the main steam pipeline

Technical field

The invention belongs to the technical field of the thermal power generation industry and relates to a real-time calculation method for the safety risk of three-level over-limit pressure of main steam pipelines.

Background technique

The main steam system of a thermal power plant sends the steam generated by the boiler to the steam turbine to perform work. It is composed of the main steam pipeline, valves and drain devices from the boiler superheater outlet header to the turbine inlet main steam valve. The main steam pipeline is the most important component. As one of the four major pipelines in thermal power plants, its importance is self-evident.

Since the main steam pressure value of thermal power generating units is often hundreds of times the atmospheric pressure, for example, the value of ultra-supercritical units can reach 27MPa (270 times the atmospheric pressure). Considering safety, the main steam pipeline is designed to be large in size. For thick-walled components, design institutes and boiler and turbine manufacturers will also provide appropriate design operating pressures based on various design conditions. However, during service, unstable factors may lead to poor operating conditions, resulting in overpressure in the main steam pipeline. run. The main steam pressure brings axial and circumferential internal pressure stress to the main steam pipeline. Especially during overpressure operation, in high temperature environment and large internal pressure stress environment, it will accelerate the aging of pipeline materials and cause pipe defects. In the case of stress concentration, residual stress caused by welding, and micro-crack defects, frequent overpressure or even large-scale overpressure operation will amplify the stress concentration or cause micro-crack expansion to cause failure accidents. Therefore, it is harmful to the main steam pipeline. It is necessary and important to conduct overpressure operation monitoring and even multi-level overpressure operation monitoring.

To this end, based on the three-level overpressure, a real-time calculation method for the safety risk of the three-level over-limit pressure of the main steam pipeline is proposed. The three-level pressure over-limit safety risk value is used to characterize the overpressure situation of the main steam pipeline, which is convenient for operators. Paying special attention to the operating status of the main steam pressure will help production management professionals strengthen the technical supervision of the main steam pipeline, and provide a reference for maintenance personnel to formulate targeted maintenance plans.

At present, there are only reports in the literature that use ANSYS finite element software numerical simulation to propose an equivalent stress mathematical model of the dangerous point of the main steam pipeline bend, such as the literature "Main steam pipeline life prediction based on reliability theory, 2008, North China Electric Power University ( Beijing)"; there are also literature reports that analyze the current domestic regulations for the design pressure of the main steam pipeline of super (super) critical units, and propose that the working pressure under the boiler maximum continuous evaporation capacity (BMCR) condition be used as the design pressure, such as the literature "Design pressure value of main steam pipeline of super (super) critical unit, 2010(08)". However, there is no report on the real-time calculation method of the safety risk of level three pressure overrun in the main steam pipeline of thermal power plants.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned shortcomings of the prior art and provide a real-time calculation method for the safety risk of a three-level over-limit pressure in a main steam pipeline, which can calculate the safety risk of a three-level over-limit pressure in the main steam pipeline in real time.

In order to achieve the above purpose, the real-time calculation method of the safety risk of three-level over-limit pressure of the main steam pipeline according to the present invention includes the following steps:

1) Use the real-time grid-connected switch of the unit and the values KG(t _i ) and MW(t _{i )} of the real-time generated power of the unit at the current time t _i to calculate the operating status S _A (t _i ) of the unit at the current time t i; obtain the real-time value of the unit _{Calculate the} unit operating _{status S A} (t _i-1 );

When (S _A (t _i )+S _A (t _i-1 )) ≥ 1, go to step 2);

2) Obtain the value MSP _j (t i _-1 ) of each main steam pressure measuring point at the previous time t _i- 1, and calculate the kth level overpressure state of each main steam pressure measuring point at the previous time t _i-1 S _Bk (t _i-1 ); obtain the value MSP _j (t _i ) of each main steam pressure measuring point at the current time t _i , and calculate the kth level overpressure state of each main steam pressure measuring point at the current time t _i S _Bk (t _i );

3) According to the k-th level overpressure state S _Bk (t _i-1 ) of each main steam pressure measuring point at the previous time t _i-1 and the k-th level overpressure state of each main steam pressure measuring point at the current time t _i S _Bk (t _i ) determines whether the kth level overpressure occurs;

4) When the kth level overpressure occurs, calculate the real-time overpressure safety risk value R _jk (t _i ) of each main steam pressure measuring point at the current time t _i based on the time when the kth level overpressure occurs;

5) Calculate the cumulative overpressure safety risk value R _j of each main steam pressure measuring point up to the calculation time based on the real-time overpressure safety risk value R _jk (t _i ) of each main steam pressure measuring point at the current time _ti ;

6) Calculate the cumulative overpressure safety risk value R of the main steam pipeline as of the calculation time based on the cumulative overpressure safety risk value R _j of each main steam pressure measuring point as of the calculation time.

In step 1), the unit operating status S _A (t _{i )} at the current time ti is:

The unit operating status S _A (t _i-1 ) at the previous time t _i-1 is:

In step 2), the kth-level overpressure state S _Bk (t i _-1 ) of each main steam pressure measuring point at the previous time t _i-1 is:

if MSP _j (t _i-1 ) ≥ LV _k ,S _Bk (t _i-1 )＝1, else, S _Bk (t _i-1 )＝0 (3)

The kth level overpressure state S _Bk (t _i ) of each main steam pressure measuring point at the current time t _i :

if MSP _j (t _i )≥LV _k ,S _Bk (t _i )＝1,else,S _Bk (t _i )＝0 (4)

When the kth-level overpressure state S _Bk (t _i ) of each main steam pressure measuring point at the current time t _i and the k-th level overpressure state S _Bk (t _{i-1 ) at the previous time t i-1 satisfy} When the conditions shown in equation (5) are met, the kth level overpressure does not occur;

if S _Bk (t _i-1 )＝0∨S _Bk (t _i )＝0 (5)

When the kth-level overpressure state S _Bk (t _i ) of each main steam pressure measuring point at the current time t _i and the k-th level overpressure state S _Bk (t _{i-1 ) at the previous time t i-1 satisfy} When the conditions shown in equation (6) are met, the kth level overpressure has just begun to occur;

if S _Bk (t _i-1 )＝0∨S _Bk (t _i )＝1 (6)

When the kth-level overpressure state S _Bk (t _i ) of each main steam pressure measuring point at the current time t _i and the k-th level overpressure state S _Bk (t _{i-1 ) at the previous time t i-1 satisfy} When the conditions shown in equation (7) are met, the kth level overpressure is in the process;

if S _Bk (t _i-1 )＝1∨S _Bk (t _i )＝1 (7)

When the kth-level overpressure state S _Bk (t _i ) of each main steam pressure measuring point at the current time t _i and the k-th level overpressure state S _Bk (t _{i-1 ) at the previous time t i-1 satisfy} When the conditions shown in equation (8) are met, the kth level overpressure will end:

if S _Bk (t _i-1 )＝1∨S _Bk (t _i )＝0 (8)

When the kth level overpressure of each main steam pressure measuring point begins to occur, the real-time overpressure safety risk value R _jk (t _i ) of the main steam pressure measuring point is:

When the kth level overpressure of each main steam pressure measuring point is in process, the real-time overpressure safety risk value R _jk (t _i ) of the main steam pressure measuring point is:

When the kth level overpressure of each main steam pressure measuring point will end, the real-time overpressure safety risk value R _jk (t _i ) of the main steam pressure measuring point is:

The cumulative overpressure safety risk value R _j of each main steam pressure measuring point as of the calculation time is:

Among them, t _start is the initial time for calculating the cumulative overpressure safety risk value, and t _now is the current time for calculating the cumulative overpressure safety risk value.

Calculate the cumulative overpressure safety risk value R of the main steam pipeline up to the calculation time as:

Among them, j indicates that the main steam pipeline has n main steam pressure measuring points.

The invention has the following beneficial effects:

During specific operation, the real-time calculation method of the safety risk of the main steam pipeline pressure three-level overrun according to the present invention screen the operating conditions of the unit by obtaining the real-time grid connection switch of the unit and the real-time power generation of the unit in real time, and obtains the main steam pressure measuring point in real time. The value is used to judge the three-level overpressure status, and the corresponding real-time overpressure safety risk value calculation is performed based on the overpressure status. Based on this, the real-time calculation of the cumulative overpressure safety risk value of the main steam pressure measuring point and the main steam pipeline are realized in turn. Real-time calculation of the cumulative overpressure safety risk value, using the overpressure safety risk value to characterize the overpressure situation of the main steam pipeline, providing a reference for operators to adjust main steam parameters and related parameters, and for production management personnel to carry out inspections of main steam pipelines Provide technical supervision and provide technical support for maintenance personnel to formulate targeted maintenance plans.

Description of drawings

Figure 1 is a flow chart of the present invention.

Detailed ways

In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only These are part of the embodiments of the present invention, not all of them, and are not intended to limit the scope of the disclosure of the present invention. Furthermore, in the following description, descriptions of well-known structures and techniques are omitted to avoid unnecessarily obscuring the concepts disclosed in the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts should fall within the scope of protection of the present invention.

A schematic structural diagram according to a disclosed embodiment of the present invention is shown in the accompanying drawings. The drawings are not drawn to scale, with certain details exaggerated and may have been omitted for purposes of clarity. The shapes of the various regions and layers shown in the figures and the relative sizes and positional relationships between them are only exemplary. In practice, there may be deviations due to manufacturing tolerances or technical limitations, and those skilled in the art will base their judgment on actual situations. Additional regions/layers with different shapes, sizes, and relative positions can be designed as needed.

Referring to Figure 1, the real-time calculation method of the safety risk of the three-level overrun of main steam pipeline pressure according to the present invention includes the following steps:

1) Determine the calculation object

According to the actual situation of the thermal power plant, the calculation object is the main steam pipe on side A or B of a single unit.

2) Determine condition parameters and calculation parameters

The condition parameters are: the unit’s real-time grid connection switch KG, the unit’s real-time power generation MW and the unit’s installed capacity MW _Design ;

The calculation parameters are: main steam pressure MSP;

When there are multiple main steam pressure measuring points on the main steam pipeline, they are distinguished by j in the lower right corner, and the value MSP _j of each measuring point is independently involved in the calculation.

3) Determine the level three overpressure limit

The three-level overpressure limits are respectively the first-level overpressure limit LV _I , the second-level overpressure limit LV _II and the third-level overpressure limit LV _III , where LV _I < LV _II < LV _III .

For the convenience of calculation, each level of overpressure of the three-level overpressure is uniformly represented by the subscript k in the lower right corner, and the limit value of the three-level overpressure is expressed as LV _k .

4) Start calculation and obtain real-time data

Start calculation from the current time t _i , obtain the condition parameters and calculation parameters from the database, and then go to step 5);

5) Judgment of continuous operating conditions of the unit

Obtain the condition parameters KG(t _i ) and MW(t _i ) of the real-time grid-connected switch of the unit and the real-time generated power of the unit at the current time t _i . Then the operating status S _A (t _i ) of the unit at the current time t _i is:

Obtain the condition parameters of the unit's real-time grid-connected switch and the unit's real-time power generation value KG (t _{i-1 )} and MW (t _i-1 ) at the previous moment t i-1, where the unit's real-time power generation at the previous moment t _i-1 The operating state S _A (t _i-1 ) is:

When (S _A (t _i ) + S _A (t _i-1 )) ≥ 1, the unit continues to run, then go to step 6), otherwise, go to step 4);

6) Judgment of level three overpressure status

Obtain the value MSP _j (t _{i-1 )} of each main steam pressure measuring point at the previous time t i-1, and calculate the k-th level overpressure state S _Bk of each main steam pressure measuring point at the previous time t _i-1 (t _i-1 ) is:

if MSP _j (t _i-1 ) ≥ LV _k ,S _Bk (t _i-1 )＝1, else, S _Bk (t _i-1 )＝0 (3)

Obtain the numerical value MSP _j (t _i ) of each main steam pressure measuring point at the current time t _i , and calculate the k-th level overpressure state S _Bk (t _i ) of each main steam pressure measuring point at the current time t _i :

if MSP _j (t _i )≥LV _k ,S _Bk (t _i )＝1,else,S _Bk (t _i )＝0 (4)

When the kth-level overpressure state S _Bk (t _i ) of each main steam pressure measuring point at the current time t _i and the k-th level overpressure state S _Bk (t _{i-1 ) at the previous time t i-1 satisfy} When the conditions shown in equation (5) are met, then the kth level overpressure does not occur, then go to step 4);

if S _Bk (t _i-1 )＝0∨S _Bk (t _i )＝0 (5)

When the kth-level overpressure state S _Bk (t _i ) of each main steam pressure measuring point at the current time t _i and the k-th level overpressure state S _Bk (t _{i-1 ) at the previous time t i-1 satisfy} When the conditions shown in equation (6) are met, the kth level overpressure has just begun to occur, then go to step 71);

if S _Bk (t _i-1 )＝0∨S _Bk (t _i )＝1 (6)

When the kth-level overpressure state S _Bk (t _i ) of each main steam pressure measuring point at the current time t _i and the k-th level overpressure state S _Bk (t _{i-1 ) at the previous time t i-1 satisfy} When the conditions shown in equation (7) are met, then the kth level overpressure is in process, then go to step 72);

if S _Bk (t _i-1 )＝1∨S _Bk (t _i )＝1 (7)

When the kth-level overpressure state S _Bk (t _i ) of each main steam pressure measuring point at the current time t _i and the k-th level overpressure state S _Bk (t _{i-1 ) at the previous time t i-1 satisfy} When the conditions shown in equation (8) are met, when the kth level overpressure will end, go to step 73):

if S _Bk (t _i-1 )＝1∨S _Bk (t _i )＝0 (8)

7) Calculation of real-time overpressure safety risk value of main steam pressure measuring point

For different k-th level overpressure states, according to the value MSP _j (t _i ) of each main steam pressure measuring point at the current time t _i and the value MSP _j (t _{i-1 ) at the previous time t i- 1} As well as the third-level overpressure limit LV _k , calculate the real-time overpressure safety risk value of each main steam pressure measuring point at the current time t _i , specifically as follows:

7-1) When the kth level overpressure of each main steam pressure measuring point begins to occur, the real-time overpressure safety risk value R _jk (t _i ) of the main steam pressure measuring point is:

7-2) When the kth level overpressure of each main steam pressure measuring point is in process, the real-time overpressure safety risk value R _jk (t _i ) of the main steam pressure measuring point is:

7-3) When the kth level overpressure of each main steam pressure measuring point will end, the real-time overpressure safety risk value R _jk (t _i ) of the main steam pressure measuring point is:

8) Real-time calculation of the cumulative overpressure safety risk value of the main steam pressure measuring point

According to the real-time overpressure safety risk value R _jk (t _i ) of each main steam pressure measuring point at the current time t _i , the cumulative overpressure safety risk value R _j of each main steam pressure measuring point up to the calculation time is calculated as:

Among them, t _start is the initial time for calculating the cumulative overpressure safety risk value, and t _now is the current time for calculating the cumulative overpressure safety risk value.

9) Real-time calculation of the cumulative overpressure safety risk value of the main steam pipeline

According to the cumulative overpressure safety risk value R _j of each main steam pressure measuring point as of the calculation time, the cumulative overpressure safety risk value R of the main steam pipeline as of the calculation time is calculated as:

Among them, j indicates that the main steam pipeline has n main steam pressure measuring points.

The real-time calculation of the cumulative overpressure safety risk value at each main steam pressure measuring point as of the calculation time and the cumulative overpressure safety risk value of the main steam pipeline as of the calculation time is completed, and the data is written into the database, ending this round of real-time calculation. Go to 4) to start a new round of real-time calculation.

The above embodiment is only one of the ways to realize the technical solution of the present invention. The scope of protection claimed by the present invention is not only limited by this embodiment, but also includes any technical scope disclosed by the present invention. Changes, substitutions and other implementations may be easily imagined by those skilled in the art.

Claims (10)

1. A real-time calculation method for safety risks of three-level over-limit pressure in main steam pipelines, which is characterized by including the following steps: 1) Obtain the unit's real-time grid-connected switch and the unit's real-time power generation value KG(t _{i )} and MW(t _i ) at the current time t _i , and calculate the unit operating status S _A (t _i ) at the current time t i; obtain the unit The real-time grid connection switch and the unit's real-time power generation value KG (t i _{- 1} ) and MW (t _i-1 ) at the previous moment t _i-1 are used to calculate the unit operating status S _A ( t _i-1 ); When (S _A (t _i )+S _A (t _i-1 )) ≥ 1, go to step 2); 2) Obtain the value MSP _j (t i _-1 ) of each main steam pressure measuring point at the previous time t _i- 1, and calculate the kth level overpressure state of each main steam pressure measuring point at the previous time t _i-1 S _Bk (t _i-1 ); obtain the value MSP _j (t _i ) of each main steam pressure measuring point at the current time t _i , and calculate the kth level overpressure state of each main steam pressure measuring point at the current time t _i S _Bk (t _i ); 3) According to the k-th level overpressure state S _Bk (t _i-1 ) of each main steam pressure measuring point at the previous time t _i-1 and the k-th level overpressure state of each main steam pressure measuring point at the current time t _i S _Bk (t _i ) determines whether the kth level overpressure occurs; 4) When the kth level overpressure occurs, calculate the real-time overpressure safety risk value R _jk (t _i ) of each main steam pressure measuring point at the current time t _i based on the time when the kth level overpressure occurs; 5) Calculate the cumulative overpressure safety risk value R _j of each main steam pressure measuring point up to the calculation time based on the real-time overpressure safety risk value R _jk (t _i ) of each main steam pressure measuring point at the current time _ti ; 6) Calculate the cumulative overpressure safety risk value R of the main steam pipeline as of the calculation time based on the cumulative overpressure safety risk value R _j of each main steam pressure measuring point as of the calculation time. 2. The real-time calculation method for the safety risk of three-level overrun of main steam pipeline pressure according to claim 1, characterized in that in step 1), the unit operating status S _A (t _{i )} at the current time ti is: The unit operating status S _A (t _i-1 ) at the previous time t _i-1 is: 3. The real-time calculation method for the safety risk of three-level overrun of main steam pipeline pressure according to claim 1, characterized in that in step 2), the kth level of each main steam pressure measuring point at the previous time t _i-1 The overpressure state S _Bk (t _i-1 ) is: if MSP _j (t _i-1 ) ≥ LV _k ,S _Bk (t _i-1 )＝1, else, S _Bk (t _i-1 )＝0 (3) The kth level overpressure state S _Bk (t _i ) of each main steam pressure measuring point at the current time t _i is: if MSP _j (t _i ) ≥ LV _k , S _Bk (t _i ) = 1, else, S _Bk (t _i ) = 0 (4). 4. The real-time calculation method for the safety risk of three-level over-limit pressure of the main steam pipeline according to claim 1, characterized in that when each main steam pressure measuring point is in the k-th level overpressure state S _Bk at the current time t _i (t _i ) and the k-th level overpressure state S _Bk (t _i-1 ) at the previous moment t i _-1 satisfy the conditions shown in equation (5), then the k-th level overpressure does not occur; if S _Bk (t _i-1 )=0∨S _Bk (t _i )=0 (5). 5. The real-time calculation method for the safety risk of three-level over-limit pressure of the main steam pipeline according to claim 1, characterized in that when each main steam pressure measuring point is in the k-th level overpressure state S _Bk at the current time t _i (t _i ) and the k-th level overpressure state S _Bk (t i _-1 ) at the previous time t _i-1 satisfy the conditions shown in equation (6), then the k-th level overpressure has just begun to occur; if S _Bk (t _i-1 )=0∨S _Bk (t _i )=1 (6). 6. The real-time calculation method for the safety risk of three-level over-limit pressure of the main steam pipeline according to claim 1, characterized in that when each main steam pressure measuring point is in the k-th level overpressure state S _Bk at the current time t _i (t _i ) and the k-th level overpressure state S _Bk (t _i-1 ) at the previous moment t _i-1 satisfy the conditions shown in equation (7), then the k-th level overpressure is in the process; if S _Bk (t _i-1 )=1∨S _Bk (t _i )=1 (7). 7. The real-time calculation method for the safety risk of three-level over-limit pressure of the main steam pipeline according to claim 1, characterized in that when each main steam pressure measuring point is in the k-th level overpressure state S _Bk at the current time t _i (t _i ) and the k-th level overpressure state S _Bk (t i- ₁ ) at the previous time t _i-1 satisfy the conditions shown in equation (8), then the k-th level overpressure will end: if S _Bk (t _i-1 )=1∨S _Bk (t _i )=0 (8). 8. The real-time calculation method for the safety risk of the three-level over-limit pressure of the main steam pipeline according to claim 1, characterized in that when the k-th level overpressure of each main steam pressure measuring point just begins to occur, the main steam The real-time overpressure safety risk value R _jk (t _i ) of the pressure measuring point is: When the kth level overpressure of each main steam pressure measuring point is in process, the real-time overpressure safety risk value R _jk (t _i ) of the main steam pressure measuring point is: When the kth level overpressure of each main steam pressure measuring point will end, the real-time overpressure safety risk value R _jk (t _i ) of the main steam pressure measuring point is: 9. The real-time calculation method of safety risk of three-level over-limit of main steam pipeline pressure according to claim 1, characterized in that the cumulative overpressure safety risk value _Rj of each main steam pressure measuring point up to the calculation time is: Among them, t _start is the initial time for calculating the cumulative overpressure safety risk value, and t _now is the current time for calculating the cumulative overpressure safety risk value. 10. The real-time calculation method of the safety risk of the three-level overpressure of the main steam pipeline according to claim 1, characterized in that the cumulative overpressure safety risk value R of the main steam pipeline up to the calculation time is: Among them, j indicates that the main steam pipeline has n main steam pressure measuring points.