Simulation of migration and accumulation of obstructions in open channel water intake of coastal power plants and water intake safety assessment method

Abstract

The present invention relates to a method for simulating the migration and aggregation of blockages in open channel water intake of coastal power plants and assessing water intake safety, including: determining a far zone index-the risk rate of the source of blockages, determining a middle zone index-the scope of the water intake boundary layer influence zone, determining a middle zone index-the relative aggregation of particles in the water intake boundary layer influence zone, determining a near zone index-the water intake entrainment rate, determining a near zone index-the water intake entrainment intensity, and analyzing the migration and aggregation state of blockages in open channel water intake. Aiming at the limitations of the current open channel water intake safety assessment method for coastal power plants based on a single evaluation index, the present invention proposes three scales of far, middle and near and five levels of evaluation indexes, and on this basis gives the detailed steps of the open channel water intake blockage risk assessment method, provides quantitative evaluation indicators for the optimization of water intake schemes and the determination of the suitability of the pollution removal capacity of the water intake system, provides a scientific basis for the scientific and effective assessment of the open channel water intake risk of coastal power plants, and provides technical support for ensuring water intake safety.

Description

Technical Field

[0001] The present invention relates to a comprehensive assessment method for the blockage risk of open channel water intake in coastal power plants based on multiple indicators, a safe operation prediction method for hydraulic engineering projects, and a method for simulating the migration and aggregation of blockages and assessing water intake safety in open channel water intake in coastal power plants. Background Art

[0002] Thermal power plants and nuclear power plants built along the coast usually adopt direct cooling, using seawater from the sea area near the plant site as the circulating cooling water source. The operating status of the water intake directly affects the safety, reliability and economy of the power plant unit operation. If marine organisms, floating objects and other blockages invade the water intake system, it may cause the power plant to lose all or part of its cooling source, causing unplanned shutdowns or reactor shutdowns, and thus impacting the safe and stable operation of the power grid. Therefore, it is necessary to evaluate the peripheral environment of the water intake open channel and predict possible blockages so that measures can be taken in advance to avoid blockages and maintain normal power generation operations.

[0003] Most of the existing water intake safety assessment methods are based on a single evaluation indicator. For example, they are only aimed at sudden and drastic changes in a certain aquatic organism. The existing single evaluation indicator assessment method is still quite effective for the assessment of single factor events, such as the sudden jellyfish blockage outside the open channel of a nuclear power plant, which caused the water intake to be blocked and caused an emergency shutdown. For the large-scale reproduction of jellyfish, the existing single indicator assessment method can basically accurately predict the rapid growth of jellyfish. However, since sudden open channel blockage events are often caused by multiple factors, and the factors that cause them are not very clear, this single indicator assessment method has great limitations, and the assessment results may be greatly different from the actual situation. Considering the limitations of computing resources, it is impossible to consider all influencing factors. Therefore, how to accurately assess the risk of open channel blockage of water intake while fully considering relevant factors is a problem that needs to be solved. Summary of the invention

[0004] In order to overcome the problems of the prior art, the present invention proposes a method for simulating the migration and accumulation of blockages in the open channel of a coastal power plant and assessing water intake safety. The method combines the tidal characteristics of the engineering sea area, the source risk of blockages and the law of migration and accumulation, the water intake convergence effect at the front edge of the water intake gate, the layout of the pollution interception net and the pollution removal capacity, etc., and proposes multi-scale and multi-level evaluation indicators. Based on this, a multi-indicator-based risk assessment method for the blockage of the open channel of a coastal power plant water intake is established, thereby providing a basic basis for determining the suitability of the pollution removal capacity of the open channel water intake system of the power plant and optimizing the water intake plan.

[0005] The object of the present invention is achieved by: a method for simulating the migration and aggregation of blockages in an open channel of a coastal power plant and assessing water safety, wherein the blockages are used as tracer particles for simulation;

[0006] The steps of the method are as follows:

[0007] Step 1: Determine the remote area index - the risk rate R of the source of the blockage: The determination method is as follows:

[0008] Sub-step 101, establishing a mathematical model: according to the coastline topography of the project sea area, the layout of the power plant intake and discharge, and the intake and discharge flow, a mathematical model of the tidal field in a large area and the migration and movement of tracer particles is established;

[0009] Sub-step 102, calibration verification of tidal current field: calibration verification of tidal current field is performed based on the full tidal hydrological measured data of the project sea area;

[0010] Sub-step 103, selecting the section for placing the line source of the obstruction in the far area of ​​water intake: firstly, analyzing and determining the sea area type of the water intake project; then selecting the appropriate section for placing the line source in the far area according to the different types;

[0011] Sub-step 104, line source release: release continuously at a certain time interval Δt, assuming that the density of the blockage in the unit water body is G a , divide the line source delivery section into n sub-sections (i = 1, 2, ..., n), the length of the i-th sub-section is B i , the average water depth is H i The average tidal flow velocity is V i , then the particle delivery intensity per unit time in the i-th section is M i =B i H i V i G a ; If the release time interval is Δt, the number of particles released each time in the i-th section is Q li =ΔtB i H i V i G a ;

[0012] Sub-step 105, calculate the remote area index - the risk rate of the source of the blockage R: use a mathematical model to simulate the migration and aggregation of the tracer particles with the tide under the placement method described in sub-step 104; first count the total number of particles N entering the water intake channel in ; Secondly, by marking and tracing the particles entering the open water intake channel, the number of particles originating from the i-th sub-section of the offshore line source delivery section is obtained as N li ; Based on this, calculate the risk rate of the source of blockage in the i-th sub-section

[0013] Step 2: Determine the middle area index - the water intake boundary layer impact area range A ef :The determination method is as follows:

[0014] Sub-step 201, selecting the range of the blockage surface source: the surface source range is large enough to cover the influence range of the water intake boundary layer and its peripheral transition area that is not directly affected by water intake, and at least covers the maximum possible migration range of water flow particles during a rising and falling tide process starting from the open channel inlet;

[0015] Sub-step 202, surface source deployment: select unfavorable tide type and unfavorable tide state, deploy once, calculate the duration T, consider the 2-3 days of tide level process, divide the deployed surface source into n sub-areas (i = 1, 2, ..., n), the area of ​​the i-th sub-area is A i , then the number of particles placed in the i-th sub-area is Q ai =A i H i G a ;

[0016] Sub-step 203, draw the contour line of water intake entrainment probability P: use a mathematical model to simulate and calculate the migration and aggregation of tracer particles with tide under the delivery method described in sub-step 202, first count the total number of particles N entering the water intake open channel in Secondly, by marking and tracing the particles entering the open water intake channel, the number of particles originating from the i-th sub-area on the surface source is obtained as N ai , based on which the water entrainment probability of the i-th sub-area is calculated According to P i (i=1,2,…,n) performs spatial interpolation and draws the contour map of water intake probability P accordingly;

[0017] Sub-step 204, draw the entrainment probability envelope diagram for P>0, the envelope range is the range of the water intake boundary layer influence area, and calculate the envelope range area A ef ;

[0018] Step 3: Determine the middle zone index - the relative aggregation of particles in the water intake boundary layer influence zone G ％ :The determination method is as follows:

[0019] Sub-step 301, searching for sub-regions within the surface source delivery range that are within the water intake boundary layer influence area: according to the water intake boundary layer influence area determined in step 2, determining one by one whether sub-regions i (i=1, 2, ..., n) within the surface source delivery range are within the water intake boundary layer influence area, and if so, recording them in sequence j; assuming that there are m sub-regions within the water intake boundary layer influence area, then j=1, 2, ..., m;

[0020] Sub-step 302, calculate the water volume and the number of particles contained in each sub-region of the j-th sequence: the area of ​​the j-th sub-region is A j , the average water depth is H j , the volume of water is V j =A j Hj , according to the calculation results of step 2, count the number of particles N in the jth sub-region j ;

[0021] Sub-step 303, calculate the water volume weighted average particle density G in the water intake boundary layer influence area in :

[0022] Sub-step 304, calculating the relative aggregation degree G of particles in the water intake boundary layer influence area ％ :

[0023] Step 4: Determine the near-area index - water entrainment rate P s :The determination method is as follows:

[0024] Sub-step 401, defining the open channel range: taking the open channel mouth as the boundary line, and the area from the boundary line to the root of the open channel as the water intake open channel range, as the range for counting the number of particles entering the water intake open channel;

[0025] Sub-step 402, total number of particles delivered from surface sources: Count the total number of particles delivered from surface sources in sub-step 202, N s :N s =∑Q i (i=1,2,…,n);

[0026] Sub-step 403, counting the total number of particles N entering the water intake open channel in : Based on the calculation results after the surface source is placed in step 2, the total number of particles N entering the open water intake channel at time t is counted in-t (t=0,1,…,T), the total number of particles N entering the water intake channel at time T in-T ;

[0027] Sub-step 404, giving the water entrainment rate P s-t Curve over time: Based on Calculate the water entrainment rate P at time t (t = 0, 1, 2, ..., T) s-t , giving the water entrainment rate variation process P s-t ~t;

[0028] Sub-step 405, calculate the final water entrainment rate P s-T :in accordance with Calculate the water entrainment rate P at the final time T s-T ;

[0029] Step 5: Determine the near-area index - water suction intensity I in :The determination method is as follows:

[0030] Sub-step 501, counting the number of particles N that enter the water intake channel at time t in (t): Based on the calculation results of the surface source in step 2, the number of particles N that enter the water intake channel at time t is counted in (t), that is, the number of particles entrained by water at the instant; plot N in (t)~t variation curve, giving N in (t) time when the peak value appears;

[0031] Sub-step 502, counting the relative flow rate R(t) of water intake at time t: Based on the calculation results of the tidal field in step 2, counting the relative flow rate of water intake at time t That is, the number of particles sucked by water at the instant; plot N in (t)~t variation curve, giving N in (t) time when the peak value appears;

[0032] Sub-step 503, analyzing the correlation: the number of particles N sucked by the instantaneous water intake in The curves of tide level H(t)~t, tide level H(t)~t and tide level R(t)~t are plotted on one graph to analyze and explain N in (t) The correlation between the time of peak occurrence and tide level and relative flow rate of water intake;

[0033] Sub-step 504, water inlet door width segmentation: divide the water inlet door width B in It is divided into several segments with equal spacing, and the length of each segment is Taking the left bank of the water intake channel as the starting point and the right bank as the end point, the distance from the left bank is y, then the coordinates of the kth segment are Count the number of instantaneous particles N entrained at time t and segment k in (y k , t), calculate the water suction strength of this section at this moment

[0034] Sub-step 505, find the position where the water intake suction intensity peaks: plot the water intake suction intensity I at the characteristic moments of rapid rise, rest rise, rapid fall, and rest fall in (y, t) distribution curve along the horizontal y of the mouth, that is, I in (y, t)~y, find the position where the water suction intensity peaks;

[0035] Step 6, analyze the migration and aggregation status of open channel water intake blockages: Based on the particle density of the surface source in step 2 and the density of the actual blockages in the corresponding project, combined with the calculation results of the water intake suction intensity at the inlet section of the water intake open channel, analyze and determine the suitability of the water intake system's pollution removal capacity, and provide a basis for optimizing the water intake plan.

[0036] The advantages and beneficial effects of the present invention are as follows: in view of the limitations of the current open channel water intake safety assessment method for coastal power plants based on a single evaluation indicator, the present invention proposes three scales of long, medium and short distances and five levels of evaluation indicators, and on this basis gives detailed steps of the open channel water intake blockage risk assessment method, and the simulation research work is closely linked to the actual project, so that the risk assessment results of the coastal power plant water intake blockage can more objectively and truly reflect the actual situation, and provide quantitative evaluation indicators for the optimization of water intake schemes and the suitability judgment of the pollution removal capacity of the water intake system, etc., and provide a scientific basis for the scientific and effective assessment of the open channel water intake risk of coastal power plants, and provide technical support for ensuring water intake safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0038] Figure 1 is a flow chart of the method described in an embodiment of the present invention;

[0039] Figure 2 It is a grid map of an engineering sea area of ​​an application example of the method described in an embodiment of the present invention;

[0040] Figure 3 It is a grid diagram of the vicinity of a water intake of an application example of the method described in an embodiment of the present invention;

[0041] Figure 4 It is a schematic diagram of the flow field near the water intake during rapid water inflow in an application example of the method described in an embodiment of the present invention;

[0042] Figure 5 It is a schematic diagram of the flow field near the water intake during high and normal times in an application example of the method described in an embodiment of the present invention;

[0043] Figure 6 It is a schematic diagram of the flow field near the water intake when the water is falling rapidly in an application example of the method described in the embodiment of the present invention;

[0044] Figure 7 Schematic diagram of the flow field near the water intake in low and normal times of an application example of the method described in an embodiment of the present invention;

[0045] Figure 8 It is a schematic diagram of the line source placement position of an application example of the method described in an embodiment of the present invention;

[0046] Fig. 9 It is a schematic diagram of the particle tracing result of entering the water intake open channel in the application example of the method described in the embodiment of the present invention;

[0047] Fig.10 A schematic diagram of a surface source delivery setting of an application example of the method described in an embodiment of the present invention;

[0048] Fig.11A schematic diagram of the entrainment probability P contour lines of an application example of the method according to an embodiment of the present invention;

[0049] Fig.12 Relative aggregation degree G of particles in the water intake boundary layer influence zone of the application example of the method described in the embodiment of the present invention ％ Schematic diagram of the curve changing over time;

[0050] Fig.13 The water entrainment rate P of the application example of the method described in the embodiment of the present invention s Schematic diagram of the curve changing over time;

[0051] Fig.14 The number of particles N that instantly enter the open water intake channel in the application example of the method described in the embodiment of the present invention in Schematic diagram of the curve changing over time;

[0052] Fig.15 A schematic diagram of a curve showing the change of the relative flow rate R(t) of water intake over time in an application example of the method described in an embodiment of the present invention;

[0053] Fig.16 Instantaneous water entrainment particle strength I of the application example of the method described in the embodiment of the present invention in (t), tidal level H(t), and relative flow rate R(t) of water intake change with time;

[0054] Fig.17 Segmented instantaneous particle entrainment intensity I of the application example of the method described in the embodiment of the present invention in (t)(x k , t) Schematic diagram of the curve changing with time;

[0055] Fig.18 The instantaneous particle entrainment intensity I of the application example of the method described in the embodiment of the present invention at the moment of rapid expansion in (x k , t) Schematic diagram of the change of the horizontal coordinates of the door;

[0056] Fig.19 The instantaneous particle entrainment intensity I at the expansion and rest time of the application example of the method described in the embodiment of the present invention in (x k , t) Schematic diagram of the change of the horizontal coordinates of the door;

[0057] Fig. 20 The instantaneous particle entrainment intensity I of the falling moment of the application example of the method described in the embodiment of the present invention in (x k , t) Schematic diagram of the change of the horizontal coordinates of the door;

[0058] Fig.21 The instantaneous particle entrainment intensity I at the time of rest in the application example of the method described in the embodiment of the present inventionin (x k , t) Schematic diagram of the change of the lateral coordinates of the door. DETAILED DESCRIPTION

[0059] Example:

[0060] This embodiment is a method for simulating the migration and aggregation of blockages in the open channel water intake of a coastal power plant and assessing water intake safety. In the method described, the blockages are simulated as tracer particles. Five indicators are proposed, including 1 far-zone indicator, 2 mid-zone indicators, and 2 near-zone indicators. The details are as follows:

[0061] Indicator 1: Far area indicator - risk rate of blockage source R. Indicator 2: Middle area indicator - water intake boundary layer impact area range A ef Indicator 3: Middle zone indicator - relative aggregation of particles in the water intake boundary layer influence zone G ％ Indicator 4: Near-area indicator - water suction rate P s Indicator 5: Near-area indicator - water suction intensity I in .

[0062] The specific steps of the method are as follows: Figure 1 As shown:

[0063] Step 1: Determine the remote area indicator - the risk rate of the source of blockage (the proportion of the source of blockage) R: This indicator reflects the risk of blockage of the water intake of the power plant caused by the outbreak of marine organisms or floating objects at different locations in the open sea. The determination method is as follows:

[0064] Sub-step 101, establishing a mathematical model: according to the coastline topography of the engineering sea area, the layout of the power plant intake and discharge, and the intake and discharge flow, a mathematical model of the tidal field in a large area and the migration and movement of tracer particles is established.

[0065] Application examples (the application examples in the following steps are all continuations of the application examples in this step):

[0066] The sea area of ​​a nuclear power plant with a length of 60 km from east to west and a width of 30 km from north to south is used as the calculation domain of the mathematical model of the tidal field. Figure 2 , 3 The southern boundary is the coastline ( Figure 2 , 3 According to the rule of north up, south down, west on the left and east on the right, the south is down. The water intake is located at the midpoint of the south, with a width of 50m and a length of 400m for the water intake channel. The sea area involved in the engineering sea area grid is 60km wide and extends 22km overseas. Figure 2 The grid width near the water intake is 4 km and extends 800 meters offshore. Figure 3 , the depth of the entire calculation domain is taken as 10m, and it is a triangular grid. Figure 2As shown in the figure, the grid is divided into four areas. The grid near the water intake is relatively dense, and the grid gradually expands. The tidal field is driven by the tidal difference between the east and west boundaries. The west tidal level is taken as a sine function with an amplitude of 0.8m and a period of 12h, and the east tidal level is taken as a negative cosine function with an amplitude of 0.8m and a period of 12h. The northern boundary is a free slip boundary. The simulation period is from 0:00 on January 1, 2000 to 0:00 on January 9, 2000, of which 0:00 on January 1 to 0:00 on January 2 is the flow field warm-up period.

[0067] Sub-step 102, calibration and verification of tidal field: calibration and verification of tidal field is performed based on the full-tidal hydrological measured data of the project sea area.

[0068] Application example: Measure the flow fields of several types of sea tides in the water intake open channel, including: the flow field near the water intake during rapid rise, the flow field near the water intake during high and normal times, the flow field near the water intake during rapid fall, and the flow field near the water intake during low and normal times. Figures 4 to 7 shown.

[0069] Figure 4 It is the flow field near the water intake at the moment of rapid rise. At this time, the flow direction is from west to east, and the maximum flow velocity is greater than 0.5m / s, which occurs in the area 200-400m offshore. The flow velocity within 200m offshore is between 0.3-0.45m / s, and the flow velocity at the open channel mouth of the water intake is between 0.35-0.45m / s.

[0070] Figure 5 This is the flow field near the water intake at high temperatures. At this time, the flow direction is from west to east, and the maximum flow velocity is greater than 0.5m / s, appearing in the area 500m away from the shore. The flow velocity within 100m from the shore is between 0.2-0.3m / s, within 100-200m from the shore is between 0.3-0.4m / s, within 200-500m from the shore is between 0.4-0.5m / s, and the flow velocity at the open channel mouth of the water intake is between 0.25-0.35m / s.

[0071] Figure 6 It is the flow field near the water intake at the moment of emergency. At this time, the flow direction is from east to west. Except for the flow velocity within about 50m near the shore between 0.4-0.5m / s, the flow velocity in other areas is greater than 0.5m / s, and the flow velocity at the water intake open channel mouth is between 0.3-0.45m / s.

[0072] Figure 7It is the flow field near the water intake at low moments. At this time, the flow direction is from east to west, with the maximum flow velocity between 0.45-0.5m / s, basically appearing in the area 400m away from the shore, the flow velocity within 100m from the shore is between 0.15-0.3m / s, the flow velocity within 100-200m from the shore is between 0.3-0.4m / s, the flow velocity within 200-400m from the shore is between 0.4-0.45m / s, and the flow velocity at the open channel mouth of the water intake is between 0.2-0.35m / s.

[0073] Sub-step 103, select the line source release section of the distant water intake obstruction: the sea area where the water intake project is located can be divided into semi-enclosed bays, reciprocating flow sea areas, and rotating flow sea areas. First, analyze and determine the sea area type of the water intake project; then select the appropriate distant line source release section according to the different types. Specifically as follows: for semi-enclosed bays, the bay mouth control section is used as the line source release section; for reciprocating flow sea areas, the rectangular boundary with the water intake gate as the center and 15km along the shore and 15km offshore is used as the line source release section; for rotating flow sea areas or mixed flow sea areas, the arc boundary with the water intake open channel gate as the center and a radius of 15km is used as the line source release section.

[0074] The sea area of ​​the application example is a reciprocating flow sea area. The rectangular boundary with the water intake gate as the center and 15km along the shore and 15km offshore is used as the line source delivery section. The line source is set as a south opening rectangle, such as Figure 8 A total of 226 point sources are set up, and the distance between point sources is B = 200m. Figure 8 The middle box indicates the release position. Starting from 0:00 on January 2, 2000, a particle is released every time interval Δt = 300s until the end of the simulation. The line source release parameters are shown in Table 1.

[0075] Table 1. Line source delivery parameters

[0076] parameter Value unit Δt 300 s n 226 indivual <![CDATA[B i ]]> 200 m <![CDATA[H i ]]> 10 m <![CDATA[V i ]]> 0.594 m / s <![CDATA[G a ]]> <![CDATA[2.8×10 -6 ]]> <![CDATA[per / m 3 > <![CDATA[M i ]]> 1 pcs / s <![CDATA[Q i ]]> 300 indivual

[0077] Sub-step 104, line source release: release continuously at a certain time interval Δt, assuming that the density of the blockage in the unit water body is G a (Unit: pieces / m 3 ), divide the line source delivery section into n sub-sections (i = 1, 2, ..., n), and the length of the i-th sub-section is B i (Unit: m), average water depth is H i (Unit: m), the average tidal velocity is V i (Unit: m / s), then the particle delivery intensity per unit time in the i-th section is M i =B i H i V i G a(Unit: pieces / s); if the time interval between releases is Δt, the number of particles released each time in the i-th section is Q li =ΔtB i H i V i G a (Unit: piece). Sub-section length B i It should not be too large, otherwise it will not be possible to accurately capture the location of offshore risk sources. The continuous release time should be sufficient to ensure that the particles in the line source release section can be transported to the water intake area with the tide.

[0078] Application example: After 7 days of particle placement, the total number of particles N entering the water intake channel in =63, the traceability results are as follows Fig. 9 shown.

[0079] Sub-step 105, calculate the remote area index - the risk rate of the source of the blockage R: use a mathematical model to simulate the migration and aggregation of the tracer particles with the tide under the placement method described in sub-step 104; first count the total number of particles N entering the water intake channel in ; Secondly, by marking and tracing the particles entering the open water intake channel, the number of particles originating from the i-th sub-section of the offshore line source delivery section is obtained as N li ; Based on this, calculate the risk rate of the source of blockage in the i-th sub-section

[0080] Application example: Calculate the risk rate of the source of blockage in the first sub-section:

[0081]

[0082] Step 2: Determine the middle area index - the water intake boundary layer impact area range A ef :This indicator reflects the influence range of the water intake suction effect of the power plant. The offshore tide flows through the front edge of the open channel water intake. The water flow of a certain width near the shore on the water intake side and the blockages it carries will enter the water intake open channel under the influence of water intake suction confluence. The larger the influence range of the water intake boundary layer, the stronger the water intake suction effect, and the greater the risk of water intake being blocked. The determination method is as follows:

[0083] Sub-step 201, select the range of the obstruction surface source: the surface source range is large enough to cover the influence range of the water intake boundary layer and its peripheral transition area that is not directly affected by water intake. At least cover the maximum possible migration range of water flow particles during a rising and falling tide process starting from the open channel inlet.

[0084] The range (setting) of the blockage surface source selected in the application example is as follows: Fig.10 shown. Fig.10 It is a semicircular dot array set up for surface source delivery, with a radius of 5km, a dot array spacing of 200m, and a total of 997 delivery points.

[0085] Sub-step 202, non-point source delivery: select unfavorable tide type and unfavorable tide state, and deliver once. The calculation time T can consider the tide level process of 2 to 3 days. Assume that the density of the blockage in the unit water body is G a (Unit: pieces / m 3 ). Divide the surface source into n sub-areas (i = 1, 2, ..., n), and the area of ​​the i-th sub-area is A i (Unit: m 2 ), then the number of particles placed in the i-th sub-area is Q ai =A i H i G a (Unit: piece).

[0086] Application example: Surface source delivery method: select unfavorable tide type, deliver once, and calculate the duration for 7 days. Surface source delivery parameters are shown in Table 2.

[0087] Table 2. Surface source delivery parameters

[0088] parameter Value unit n 997 indivual <![CDATA[A i ]]> 40000 <![CDATA[m 2 ]]> <![CDATA[H i ]]> 10 m <![CDATA[G a ]]> 0.0005 <![CDATA[per / m 3 > <![CDATA[Q ai ]]> 200 indivual

[0089] Sub-step 203, draw the contour line of water intake entrainment probability P: use a mathematical model to simulate and calculate the migration and aggregation of tracer particles with tide under the delivery method described in sub-step 202, first count the total number of particles N entering the water intake open channel in Secondly, by marking and tracing the particles entering the open water intake channel, the number of particles originating from the i-th sub-area on the surface source is obtained as N i , based on which the water entrainment probability of the i-th sub-area is calculated According to P i (i=1,2,…,n) is used for spatial interpolation, and a contour map of the water intake probability P is drawn accordingly.

[0090] The contour map of water intake probability P of the application example is as follows: Fig.11 shown. Fig.11 It is a contour map of the water intake entrainment probability P under the condition of surface source delivery. In the current tidal field, the probability of water intake entrainment is relatively high within the rectangular range of about 200m north of the water intake and about 500m east and west. There is also an entrainment risk area within the 200m nearshore range 5km to the west, but the probability is relatively small.

[0091] Sub-step 204, draw the entrainment probability envelope diagram for P>0, the envelope range is the range of the water intake boundary layer influence area, and calculate the envelope range area A ef .

[0092] Application example: According to Fig.11 Calculate the area of ​​the water boundary layer influence zone A ef =7.4518×105 m 2 .

[0093] The area of ​​the water intake boundary layer A ef It is the area enclosed by the entrainment probability envelope line of P>0 in the contour map of water intake entrainment probability P.

[0094] Step 3: Determine the middle zone index - the relative aggregation of particles in the water intake boundary layer influence zone G ％ : G in Calculate the volume-weighted average particle density of water in the water boundary layer influence area after a certain period of time or after the end of step 2, G a Calculate the particle density of the water body in the initial state of the surface source area for step 2. Relative aggregation G ％ It reflects the potential risk of water intake being blocked. The determination method is as follows:

[0095] Sub-step 301, finding the sub-regions within the surface source delivery range that are within the water intake boundary layer influence area: Based on the water intake boundary layer influence area determined in step 2, determine one by one whether the sub-regions i (i = 1, 2, ..., n) within the surface source delivery range are within the water intake boundary layer influence area, and if "yes", record them in the sequence j. Assuming that there are m sub-regions in total within the water intake boundary layer influence area, then j = 1, 2, ..., m.

[0096] Sub-step 302, calculate the water volume and the number of particles contained in each sub-region of the j-th sequence: the area of ​​the j-th sub-region is A j , the average water depth is H j , the volume of water is V j =A j H j According to the calculation results of step 2, count the number of particles N in the jth sub-region j .

[0097] Sub-step 303, calculate the water volume weighted average particle density G in the water intake boundary layer influence area in :

[0098] Sub-step 304, calculating the relative aggregation degree G of particles in the water intake boundary layer influence area ％ :

[0099] Relative aggregation of particles in the boundary layer of the water taken from the application example 0 to 6 days after release G ％ Change curve, such as Fig.12 shown. Fig.12 is the relative aggregation degree of particles in the water boundary layer influence zone G ％ Curve changing over time, after delivery, G ％In the first two days, the water showed fluctuating characteristics with the tide, but the peak gradually decayed. After January 4, because the particles left the water intake boundary layer influence area with the flow or were sucked into the open channel, G ％ becomes 0 and does not change over time.

[0100] Step 4: Determine the near-area index - water entrainment rate P s : Water suction rate P s Defined as the total number of particles N entering the open intake channel in Total amount of surface source N s The two indicators directly reflect the entrainment effect of open channel water intake. The determination method is as follows:

[0101] Sub-step 401, defining the open channel range: taking the open channel mouth as the boundary line, and the area from the boundary line to the root of the open channel as the water intake open channel range, as the range for counting the number of particles entering the water intake open channel.

[0102] Sub-step 402, total number of particles delivered from surface sources: Count the total number of particles delivered from surface sources in sub-step 202, N s :N s =∑Q i (i=1,2,…,n);

[0103] N s =199400

[0104] Sub-step 403, counting the total number of particles N entering the water intake open channel in : Based on the calculation results after the surface source is placed in step 2, the total number of particles N entering the water intake open channel at time y is counted in-t (t=0,1,…,T), the total number of particles N entering the water intake channel at time T in-T .

[0105] Sub-step 404, giving the water entrainment rate P s-t Curve over time: Based on Calculate the water entrainment rate P at time t (t = 0, 1, 2, ..., T) s-t , giving the water entrainment rate variation process P s-t ~t.

[0106] Application example: The water entrainment rate changes with time. Fig.13 shown. Fig.13 is the change of water entrainment rate over time. In the first 4 hours after the release, the entrainment rate P s-t Rapid growth, followed by intermittent growth, and then a slowdown in growth. Finally, since the released particles migrate with the flow and leave the water intake boundary layer influence area, there are no new particles entering the water intake open channel, and the entrainment rate P s-t tends to a constant value.

[0107] Sub-step 405, calculate the final water entrainment rate P s-T :in accordance with Calculate the water entrainment rate P at the final time T s-T .

[0108]

[0109] Step 5: Determine the near-area index - water suction intensity I in :This indicator is defined as the number of particles entering the open channel through the water intake gate per unit time and per unit width of the water intake gate control section. This indicator can provide high-risk tide times and locations, and provide guidance for determining the suitability of the pollution removal capacity of the power plant water intake system and the implementation of water intake safety prevention and control measures. The determination method is as follows:

[0110] Sub-step 501, counting the number of particles N that enter the water intake channel at time t in (t): Based on the calculation results of the surface source in step 2, the number of particles N that enter the water intake channel at time t is counted in (t), that is, the number of particles entrained by water at the instant; plot N in (t)~t variation curve, giving N in (t) The time when the peak value appears.

[0111] The curve of the instantaneous water entrainment particle number changing with time in the application example is as follows: Fig.14 As shown, the peak time of the instantaneous water entrainment particle number was 12:00 on January 2, 2000. Fig.14 It is the curve of the change of the number of particles sucked by instantaneous water intake over time. The number of particles sucked by instantaneous water intake is defined as the total number of particles in the water intake open channel at the current moment minus the total number of particles in the water intake open channel one hour ago. The unit of intensity is pieces / h. Fig.14 The number of particles entrained in the medium instantaneous water intake increases rapidly and reaches a peak after the release, and then decays rapidly. There are still several entrainment peaks in the two days after the release, but the intensity gradually weakens and finally tends to 0.

[0112] Sub-step 502, counting the relative flow rate R(t) of water intake at time t: Based on the calculation results of the tidal field in step 2, counting the relative flow rate of water intake at time t where u in(t) is the instantaneous flow rate at the water intake gate, u a is the instantaneous flow velocity of the external flow field; draw the R(t)~t variation curve.

[0113] The relative flow rate R(t) of water intake in the application example changes with time as follows: Fig.15 shown. Fig.15It is the change of relative flow velocity R(t) over time. R(t) has strong periodicity. Two maximum peaks of about 4.5 appear at two low tide moments in one day. It is smaller during rapid tide rise and fall, about 0.5. A local smaller peak of about 2.5 appears at low tide moments.

[0114] Sub-step 503, analyzing the correlation: the number of particles N sucked by the instantaneous water intake in The curves of tide level H(t)~t, tide level H(t)~t and tide level R(t)~t are plotted on one graph to analyze and explain N in (t) The correlation between the time of peak occurrence and tide level and relative flow velocity of water intake.

[0115] Fig.16 is the number of particles N sucked by water in an instantaneous manner in the application example in The curve of change of tide level H(t)~t, the curve of change of tide level R(t)~t over time. Fig.16 Display, N in (t) The peak value occurs when the tide is low and the relative flow rate of water is maximum. Fig.16 is the number of particles N sucked up by water instantaneously in (t), tide level H(t), relative flow rate R(t) of water intake change with time, N in The peak value of (t) basically coincides with the peak value of R(t). At this time, the tide level is low, the external flow velocity is low, the water intake flow velocity is dominant, and particles are more easily sucked into the open channel.

[0116] Sub-step 504, water inlet door width segmentation: divide the water inlet door width B in Divide into several segments with equal spacing (such as segment l, numbered as k = 1, 2, ..., l), each segment length is The left bank of the water intake channel (left side in the downstream direction) is the starting point, the right bank is the end point, and the distance from the left bank is y. Then the coordinates of the kth segment are Count the number of instantaneous particles N entrained at time t and segment k in (y k , t), calculate the water suction strength of this section at this moment

[0117] In the application example, the water intake gate is divided into three sections: left, middle and right. The instantaneous particle entrainment intensity I in (x k , t) changes with time Fig.17 . Fig.17 is the instantaneous particle entrainment intensity I at the left, middle and right sections of the water intake in (x k, t) Curve of changes with time. The trends of the three-segment entrainment strength changes with time are basically consistent with the trend of the number of instantaneous water entrainment particles changes with time. The entrainment strength of the right segment is much greater than that of the left and middle segments.

[0118] Sub-step 505: plotting the water suction strength I at the characteristic moments of rapid rise, rest rise, rapid fall, and rest fall in (y, t) distribution curve along the horizontal y of the mouth, that is, I in (y, t) ~ y, find the location where the water suction intensity peaks, such as Figure 18-Figure 21 shown.

[0119] Fig.18 The instantaneous particle entrainment quantity I of the application example at the moment of rapid expansion in (x k , t) changes with the horizontal coordinate of the mouth, the horizontal coordinate is the width of the mouth and the position coordinate x, the vertical coordinate is I in (x). At the moment of rapid expansion, there are more particles on the left and middle sections, and more particles on the right.

[0120] Fig.19 is the instantaneous particle entrainment quantity I at the expansion and rest time of the application example in (x k , t) changes with the lateral coordinate of the mouth. There are basically no particles in the lateral direction of the mouth at the moment of expansion and rest.

[0121] Fig. 20 is the instantaneous particle entrainment quantity I at the moment of falling in the application example in (x k , t) changes with the horizontal coordinate of the mouth. At the instant of falling, there are many particles on the left side of the mouth, but there are no particles or very few particles in the middle and right side.

[0122] Fig.21 is the instantaneous particle entrainment quantity I at the resting moment of the application example in (x k , t) changes with the lateral coordinate of the mouth. At the instant of rest, there are a certain number of particles on the left and right sides of the mouth, while a large number of particles gather in the middle.

[0123] Step 6, analyze the migration and aggregation status of open channel water intake blockages: Based on the particle density of the surface source in step 2 and the density of the actual blockages in the corresponding project, combined with the calculation results of the water intake suction intensity (total amount, distribution) at the inlet section of the water intake open channel, analyze and determine the suitability of the pollution removal capacity of the water intake system (net, etc.), etc., to provide a basis for optimizing the water intake plan.

[0124] According to the ratio of the particle density of the surface source in step 2 and the density of the actual blockage of the corresponding project, the total amount of actual water intake suction strength (kg / h) is obtained. The total amount of suction strength is used to evaluate whether the maximum suction strength under the current water intake scheme is within the pollution removal capacity. At the same time, by analyzing the distribution of water intake suction strength in the water intake section, the interception nets in the areas with higher strength should be reinforced and monitored.

[0125] Finally, it should be noted that the above is only used to illustrate the technical solution of the present invention and is not a limitation. Although the present invention has been described in detail with reference to the preferred arrangement scheme, a person skilled in the art should understand that the technical solution of the present invention (such as the water intake method of the power plant, the application of various formulas, the sequence of steps, etc.) can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for simulating the migration and accumulation of blockages in open channel water intake of coastal power plants and assessing water intake safety, characterized in that: The method described simulates the blockage as a tracer particle; The steps of the method are as follows: Step 1: Determine the remote area index - the risk rate R of the source of the blockage: The determination method is as follows: Sub-step 101, establishing a mathematical model: establishing a mathematical model of the tidal field in a large sea area and the migration and movement of tracer particles based on the coastline topography of the project sea area, the layout of the power plant intake and discharge, and the intake and discharge flow; Sub-step 102, calibration verification of tidal current field: calibration verification of tidal current field is performed based on the full tidal hydrological measured data of the project sea area; Sub-step 103, selecting the section for placing the line source of the obstruction in the far area of ​​water intake: firstly, analyzing and determining the sea area type of the water intake project; then selecting the appropriate section for placing the line source in the far area according to the different types; Sub-step 104, line source release: release continuously at a certain time interval Δt, assuming that the density of the blockage in the unit water body is G a , divide the line source delivery section into n sub-sections (i = 1, 2, ..., n), the length of the i-th sub-section is B i , the average water depth is H i The average tidal flow velocity is V i , then the particle delivery intensity per unit time in the i-th section is M i =B i H i V i G a ; If the release time interval is Δt, the number of particles released each time in the i-th section is Q li =ΔtB i H i V i G a ; Sub-step 105, calculate the remote area index - the risk rate of the source of the blockage R: use a mathematical model to simulate the migration and aggregation of the tracer particles with the tide under the placement method described in sub-step 104; first count the total number of particles N entering the water intake channel in ; Secondly, by marking and tracing the particles entering the open water intake channel, the number of particles originating from the i-th sub-section of the offshore line source delivery section is obtained as N li ; Based on this, calculate the risk rate of the source of blockage in the i-th sub-section Step 2: Determine the middle area index - the water intake boundary layer impact area range A ef :The determination method is as follows: Sub-step 201, selecting the range of the blockage surface source: the surface source range is large enough to cover the influence range of the water intake boundary layer and its peripheral transition area that is not directly affected by water intake, and at least covers the maximum possible migration range of water flow particles during a rising and falling tide process starting from the open channel inlet; Sub-step 202, surface source deployment: select unfavorable tide type and unfavorable tide state, deploy once, calculate the duration T, consider the 2-3 days of tide level process, divide the deployed surface source into n sub-areas (i = 1, 2, ..., n), the area of ​​the i-th sub-area is A i , then the number of particles placed in the i-th sub-area is Q ai =A i H i G a ; Sub-step 203, draw the contour line of water intake entrainment probability P: use a mathematical model to simulate and calculate the migration and aggregation of tracer particles with tide under the delivery method described in sub-step 202, first count the total number of particles N entering the water intake open channel in Secondly, by marking and tracing the particles entering the open water intake channel, the number of particles originating from the i-th sub-area on the surface source is obtained as N ai , based on which the water entrainment probability of the i-th sub-area is calculated According to P i (i=1,2,…,n) performs spatial interpolation and draws the contour map of water intake probability P accordingly; Sub-step 204, draw the entrainment probability envelope diagram for P>0, the envelope range is the range of the water intake boundary layer influence area, and calculate the envelope range area A ef ; Step 3: Determine the middle zone index - the relative aggregation of particles in the water intake boundary layer influence zone G ％ :The determination method is as follows: Sub-step 301, searching for sub-regions within the surface source delivery range that are within the water intake boundary layer influence area: according to the water intake boundary layer influence area determined in step 2, determine one by one whether sub-regions i (i=1, 2, ..., n) within the surface source delivery range are within the water intake boundary layer influence area, and if so, record them in sequence j; assuming that there are m sub-regions within the water intake boundary layer influence area, then j=1, 2, ..., m; Sub-step 302, calculate the water volume and the number of particles contained in each sub-region of the j-th sequence: the area of ​​the j-th sub-region is A j , the average water depth is H j , the volume of water is V j =A j H j , according to the calculation results of step 2, count the number of particles N in the jth sub-region j ; Sub-step 303, calculate the water volume weighted average particle density G in the water intake boundary layer influence area in : Sub-step 304, calculating the relative aggregation degree G of particles in the water intake boundary layer influence area ％ : Step 4: Determine the near-area index - water entrainment rate P s :The determination method is as follows: Sub-step 401, defining the open channel range: taking the open channel mouth as the boundary line, and the area from the boundary line to the root of the open channel as the water intake open channel range, as the range for counting the number of particles entering the water intake open channel; Sub-step 402, total number of particles delivered from surface sources: Count the total number of particles delivered from surface sources in sub-step 202, N s :N s =∑Q ai (i=1,2,…,n); Sub-step 403, counting the total number of particles N entering the water intake open channel in-T : Based on the calculation results after the surface source is placed in step 2, the total number of particles N entering the open water intake channel at time t is counted in-t (t=0,1,…,T), the total number of particles N entering the water intake channel at time T in-T ; Sub-step 404, giving the water entrainment rate P s-t Curve over time: Based on Calculate the water entrainment rate P at time t (t = 0, 1, 2, ..., T) s-t , giving the water entrainment rate variation process P s-t ~t; Sub-step 405, calculating the final water entrainment rate P s-T :in accordance with Calculate the water entrainment rate P at the final time T s-T ; Step 5: Determine the near-area index - water suction intensity I in :The determination method is as follows: Sub-step 501, counting the number of particles N that enter the water intake channel at time t in (t): Based on the calculation results of the surface source in step 2, the number of particles N that enter the water intake channel at time t is counted in (t), that is, the number of particles entrained by water at the instant; plot N in (t)~t variation curve, giving N in (t) time when the peak value appears; Sub-step 502, counting the relative flow rate R(t) of water intake at time t: Based on the calculation results of the tidal field in step 2, counting the relative flow rate of water intake at time t where u in(t) is the instantaneous flow rate at the water intake gate, u a(t) is the instantaneous velocity of the external flow field; draw the R(t)~t variation curve; Sub-step 503, analyzing the correlation: the number of particles N sucked by the instantaneous water intake in The curves of tide level H(t)~t, tide level H(t)~t and tide level R(t)~t are plotted on one graph to analyze and explain N in (t) The correlation between the time of peak occurrence and tide level and relative flow velocity of water intake; Sub-step 504, water inlet door width segmentation: divide the water inlet door width B in The system is divided into several segments with equal spacing, numbered as k=1, 2, ..., l, and the length of each segment is Taking the left bank of the water intake channel as the starting point and the right bank as the end point, the distance from the left bank is y, then the coordinates of the kth segment are Count the number of instantaneous particles N entrained at time t and segment k in (y k , t), calculate the water suction strength of this section at this moment Sub-step 505, find the position where the water intake suction intensity peaks: plot the water intake suction intensity I at the characteristic moments of rapid rise, rest rise, rapid fall, and rest fall in (y, t) distribution curve along the horizontal y of the mouth, that is, I in (y, t)~y, find the position where the water suction intensity peaks; Step 6, analyze the migration and aggregation status of open channel water intake blockages: Based on the particle density of the surface source in step 2 and the density of the actual blockages in the corresponding project, combined with the calculation results of the water intake suction intensity at the inlet section of the water intake open channel, analyze and determine the suitability of the water intake system's pollution removal capacity, and provide a basis for optimizing the water intake plan.

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