A method for preventing local overheating of a tower type optical thermal mirror field heat absorber

Abstract

The present application relates to the technical field of tower type photo-thermal power station, and discloses a method for preventing local overheating of a tower type photo-thermal mirror field heat absorber, comprising the following steps: dividing the heat absorber into N small rectangular panels, calculating the power upper limit of each small rectangular panel; according to the target point strategy initially set by the mirror field, finding the small rectangular panel corresponding to the overheating area of the heat absorber and all heliostats corresponding to the small rectangular panels around the small rectangular panel; obtaining the current environmental information of the mirror field, updating the optical efficiency of the heliostats according to the light trace tracking method; and calculating the power of the i-th heliostat on the j-th small rectangular panel; establishing a 0-1 type integer linear programming model; using the implicit enumeration method to solve the above model to obtain an optimal solution, and controlling the heliostats of the mirror field according to the optimal solution. The method disclosed by the present application can eliminate local overheating as quickly as possible and reduce unnecessary power loss to the maximum extent, which is conducive to keeping the tower type photo-thermal mirror field safe and efficient operation.

Description

Technical Field

[0001] This invention relates to the field of tower solar thermal power plant technology, and in particular to a method for preventing local overheating of the receiver in a tower solar thermal mirror field. Background Technology

[0002] With more and more tower-type concentrated solar power (CSP) projects being implemented, and most of them operating well, with some even exceeding design specifications, tower-type CSP has become a popular power generation method. CSP not only boasts low power generation costs but is also a novel energy storage method, enabling continuous 24-hour power generation.

[0003] like Figure 1 As shown, the principle of tower-type concentrated solar power (CSP) is as follows: tens of thousands of heliostats 1 are arranged in different geometric shapes around a heat-absorbing tower 3. These reflect the large amount of low-density solar energy emitted by the sun 4 onto the heat absorber 2 at the top of the tower 3, transforming it into high-density solar energy, which is then converted into heat energy by the working fluid. Current CSP plants offer advantages such as high power generation efficiency, stable power output, and high-performance thermal storage. In commercial practice, they can generate electricity continuously for up to 24 hours. Tower-type CSP technology can be used for oil extraction, hydrogen production, and other applications, making it increasingly popular.

[0004] Tower-type solar thermal concentrating systems mainly consist of a mirror field and a receiver. The receiver, located hundreds of meters above the ground and prone to burnout and blockage, is particularly difficult to maintain. During mirror field operation, a special condition—localized overheating—can cause the receiver to burn out and become damaged. Therefore, the industry places great importance on solutions for localized overheating. Currently, the solution is simply to mechanically remove the heliostat corresponding to the overheated area, but this causes a decrease in power in the surrounding non-overheated areas, thus affecting receiver efficiency. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for preventing local overheating in a tower-type photothermal mirror field absorber, thereby eliminating local overheating while maximizing the preservation of power in the surrounding area.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A method for preventing local overheating in a tower-type photothermal mirror field absorber includes the following steps:

[0008] Step 1: Divide the heat absorber into N small rectangular panels, and calculate the maximum power (W) of each small rectangular panel. j This represents the upper limit of power for the j-th small rectangular panel, where j = 1, 2, ..., N;

[0009] Step two, according to the target point strategy of the mirror field initial setting, find the small rectangular panel corresponding to the super-temperature area of the heat absorber and all M heliostats corresponding to the small rectangular panel around the small rectangular panel;

[0010] Step three, obtain the current environment information of the mirror field, update the optical efficiency of the M heliostats according to the light path tracking method, and calculate the power p of the i-th heliostat on the j-th small rectangular panel according to the optical efficiency of the heliostat ij , i = 1, 2, …, M;

[0011] Step four, establish the following 0-1 type integer linear programming model:

[0012]

[0013]

[0014] Wherein, x i indicates whether the i-th heliostat participates in work, x i = 1 indicates that the i-th heliostat participates in work, i.e. reflects sunlight to the specified heat absorber panel, x i = 0 indicates that the i-th heliostat does not participate in work; the objective function f is the number of heliostats in operation;

[0015] Step five, use the implicit enumeration method to solve the above model to obtain the optimal solution (x1, x2, …, x M );

[0016] Step six, according to the obtained optimal solution, control the mirror field heliostat, if x i = 1, keep the i-th heliostat in operation, if x i = 0, remove the i-th heliostat and do not participate in operation.

[0017] In the above scheme, the calculation method of the power upper limit W j is as follows:

[0018] W j = fluxMax j · TS j

[0019] Wherein, fluxMax j indicates the maximum energy flux density, TS j indicates the area of the j-th small rectangular panel.

[0020] In the above scheme, the environment information of the mirror field includes DNI value, wind speed and temperature.

[0021] In the above scheme, the optical efficiency of the heliostat includes the cosine efficiency of the heliostat, the shading or shadow efficiency, the atmospheric projection efficiency and the overflow efficiency.

[0022] In the above scheme, the power p ij is calculated as follows:

[0023] p ij = S i · DNI · T i · cos i · M i · A i · I i

[0024] wherein S i represents the reflecting area of the ith heliostat, T i represents whether the ith heliostat is blocked by the heat tower, T i = 0 or 1, T i = 0 indicating that the heliostat is blocked, T i = 1 indicating that the heliostat is not blocked; cos i represents the cosine efficiency of the ith heliostat, M i represents the blocking or shading efficiency of the ith heliostat caused by the surrounding heliostats, A i represents the atmospheric projection efficiency of the ith heliostat, and I i represents the spillage efficiency of the ith heliostat.

[0025] By means of the above technical scheme, the method for preventing local overheating of the heat absorber of the tower type heliostat field provided by the present application has the following beneficial effects:

[0026] 1. The present application is based on an integer linear programming model, and takes the maximum number of heliostats in operation as the objective function, and reduces the temperature of the overheating area by removing the least number of heliostats, so that the overheating area can be restored to normal in the shortest time, and the local overheating can be eliminated more scientifically and rigorously.

[0027] 2. The present application aims to eliminate local overheating as quickly as possible and minimize unnecessary power loss, which is conducive to maintaining the safe and efficient operation of the tower type heliostat field. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows.

[0029] Figure 1 is a schematic view of a tower type heliostat field;

[0030] Figure 2 is a flow chart of the method for preventing local overheating of the heat absorber of the tower type heliostat field disclosed by the present application;

[0031] Figure 3 This is a schematic diagram of a heat absorber.

[0032] In the diagram, 1 is a heliostat; 2 is a receiver; 3 is a heat tower; and 4 is the sun. Detailed Implementation

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0034] This invention provides a method for preventing localized overheating in a tower-type photothermal mirror field absorber, such as... Figure 2 As shown, it includes the following steps:

[0035] Step 1: Divide the heat absorber into N small rectangular panels, and calculate the maximum power (W) of each small rectangular panel. j This represents the upper limit of power for the j-th small rectangular panel, where j = 1, 2, ..., N;

[0036] Power limit W j The calculation method is as follows:

[0037] W j =fluxMax j ·TS j

[0038] Among them, fluxMax j The maximum energy flux density, TS j This refers to the area of ​​the j-th small rectangular panel.

[0039] Step two, based on the initial target point strategy set for the mirror field, such as... Figure 3 As shown, find the small rectangular panel G0 corresponding to the overheating area of ​​the absorber, and all M heliostats corresponding to the small rectangular panels G1-G8 around this small rectangular panel.

[0040] In the design of the mirror field, the orientation of each heliostat corresponds to a target point on the receiver, and this target point is used as the point corresponding to the maximum optical efficiency of the heliostat.

[0041] Step 3: Obtain current environmental information of the heliostat field, including DNI value (direct normal irradiance, an important indicator of light resource quality), wind speed, and temperature; update the optical efficiency of the M heliostats using the light tracing method, including the heliostat's cosine efficiency, shading or shadowing efficiency, atmospheric projection efficiency, and spillover efficiency; and calculate the power p of the i-th heliostat on the j-th small rectangular panel based on the heliostat's optical efficiency. ij , i = 1, 2, ..., M. Ideally, each heliostat will only reflect light onto a few small rectangular panels.

[0042] Power pij The calculation method is as follows:

[0043] p ij = S i · DNI · T i · cos i · M i · A i · I i

[0044] Wherein, S i refers to the reflection area of the i-th heliostat, T i refers to whether the i-th heliostat is blocked by the heat tower, T i = 0 or 1, T i = 0 indicates that the heliostat is blocked, T i = 1 indicates that the heliostat is not blocked; cos i refers to the cosine efficiency of the i-th heliostat, M i refers to the shadowing or shading efficiency of the i-th heliostat caused by the surrounding heliostats, A i refers to the atmospheric projection efficiency of the i-th heliostat, I i refers to the spillage efficiency of the i-th heliostat.

[0045] Step four, the following 0-1 type integer linear programming model is established:

[0046]

[0047]

[0048] Wherein, x i refers to whether the i-th heliostat participates in work, x i = 1 indicates that the i-th heliostat participates in work, i.e. reflects sunlight to the designated heat collector panel, x i = 0 indicates that the i-th heliostat does not participate in work; the objective function f is the number of heliostats in operation; under the condition of meeting the limit, the temperature of the over-temperature area is reduced by removing the least heliostats, in other words, the over-temperature area is restored to normal in the shortest time.

[0049] Step five, the above model is solved by using implicit enumeration method to obtain the optimal solution (x1, x2, …, x M ); implicit enumeration method is the most common and efficient algorithm for solving 0-1 type integer linear programming model, which is pruned by comparing the upper and lower bounds of branching, without enumerating all solutions for calculation, greatly reducing the calculation amount.

[0050] Step six, according to the obtained optimal solution, the control of heliostat in the heliostat field is carried out, if x i = 1, the i-th heliostat is kept in operation, if xi = 0, the ith Heliostat is removed from operation.

[0051] The foregoing description of the disclosed embodiments enables a person skilled in the art to make or use the application. Numerous modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Therefore, the application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preventing local overheating in a tower-type photothermal mirror field absorber, characterized in that, Includes the following steps: Step 1: Divide the heat absorber into N small rectangular panels, and calculate the maximum power (W) of each small rectangular panel. j This represents the upper limit of power for the j-th small rectangular panel, where j = 1, 2, ..., N; Step 2: Based on the target point strategy initially set for the mirror field, find the small rectangular panel corresponding to the overheating area of ​​the receiver and all M heliostats corresponding to the small rectangular panels around the small rectangular panel. Step 3: Obtain the current environmental information of the mirror field, update the optical efficiency of the M heliostats according to the light tracing method; and calculate the power p of the i-th heliostat on the j-th small rectangular panel based on the optical efficiency of the heliostats. ij , i = 1, 2, ..., M; Step 4: Establish the following 0-1 type integer linear programming model: Where, x i Indicates whether the i-th heliostat participates in the operation, x i =1 indicates that the i-th heliostat is involved in the operation, that is, reflecting sunlight onto the designated receiver panel, x i =0 indicates that the i-th heliostat does not participate in operation; the objective function f is the number of heliostats put into operation; Step 5: Solve the above model using the implicit enumeration method to obtain the optimal solution (x1, x2, ..., x...). M ); Step six: Control the heliostat field based on the obtained optimal solution, if x i =1, then keep the i-th heliostat in operation, if x i If the value is 0, then the i-th heliostat will be removed and will not participate in the operation. Power p ij The calculation method is as follows: p ij =S i ·DNI·T i ·cos i ·M i ·TO i ·YO i Among them, S i T refers to the reflective area of ​​the i-th heliostat. i Indicates whether the i-th heliostat is blocked by the heat-absorbing tower, T i =0 or 1, T i =0 indicates that the heliostat is blocked, T i =1 indicates that the heliostat is not obstructed; cos i M refers to the cosine efficiency of the i-th heliostat. i A refers to the shading or shadowing efficiency of the i-th heliostat caused by the influence of surrounding heliostats. i I refers to the atmospheric projection efficiency of the i-th heliostat. i The overflow efficiency of the i-th heliostat.

2. The method for preventing local overheating of a tower-type photothermal mirror field absorber according to claim 1, characterized in that, Power limit W j The calculation method is as follows: W j =fluxMax j ·TS j Among them, fluxMax j The maximum energy flux density, TS j This refers to the area of ​​the j-th small rectangular panel.

3. The method for preventing local overheating of a tower-type photothermal mirror field absorber according to claim 1, characterized in that, The environmental information of the mirror field includes DNI value, wind speed, and temperature.

4. A method for preventing local overheating in a tower-type photothermal mirror field absorber according to claim 1, characterized in that, The optical efficiency of the heliostat includes its cosine efficiency, shading or shadowing efficiency, atmospheric projection efficiency, and spillover efficiency.

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