Automatic layout method for FLNG liquid cargo tank pipelines

Abstract

The invention discloses an FLNG liquid cargo tank pipeline automatic layout method, and belongs to the technical field of pipeline automatic layout. An FLNG liquid cargo tank pipeline automatic layout method comprises the steps that S1, a layout space is established, and rasterization processing is conducted on the layout space; s2, dividing grids in the layout space into an infeasible area, a high-danger area and a low-danger area according to space planning in the cargo hold; s3, assigning different risk information values to grids in the infeasible region, the high-risk region and the low-risk region, wherein the risk information value of the high-risk region is between the risk information value of the infeasible region and the risk information value of the low-risk region; s301, the height information value of the grid is calculated according to the spatial height of the grid, and the height information value is in positive correlation with the spatial height; s4, setting an evaluation function; and S5, in the high-danger area and the low-danger area, taking the minimum evaluation function as a target, and adopting a path planning algorithm to calculate an optimal arrangement route.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automatic pipeline layout, in particular to a FLNG liquid cargo tank pipeline automatic layout method. BACKGROUND

[0002] In a floating liquefied natural gas production, storage and offloading device, a large number of low-temperature, high-pressure or two-phase flow pipelines need to be arranged in the liquid cargo tank area, including liquefied natural gas loading and unloading main pipes, reliquefaction return pipes, BOG compression pipelines, safety relief / flare pipelines and utility pipe racks, etc. The liquid cargo tank is related to low temperature, high pressure, explosion prevention and other factors, and the pipeline layout design is greatly affected by environmental factors. Manual design of layout scheme has poor quality, long occupation time, and it is difficult to meet the increasing design requirements and task quantity.

[0003] Through retrieval, the existing Chinese patent CN114415679B discloses a ship engine room pipeline layout method based on an improved ant colony algorithm. The method introduces virtual nodes, and introduces safety factors, smooth factors, straight factors and length factors as pheromone heuristic functions. On this basis, the improved ant colony algorithm is used for ship engine room pipeline layout, which increases the smoothness of the pipeline, reduces the blindness and randomness of pipeline layout planning, effectively prevents pipeline layout stagnation, and improves the path search efficiency.

[0004] The above method does not consider the adverse effects of equipment in the cabin on LNG pipelines when arranging and planning pipelines. Although it can increase the smoothness of the pipeline, it cannot avoid high-pressure and high-temperature equipment, and there is a safety hazard. In view of this, we propose a FLNG liquid cargo tank pipeline automatic layout method. SUMMARY

[0005] 1. Technical problem to be solved The purpose of the present application is to provide a FLNG liquid cargo tank pipeline automatic layout method to solve the problems raised in the background.

[0006] 2. Technical scheme The present application is realized by the following technical scheme: A FLNG liquid cargo tank pipeline automatic layout method, comprising the following steps: S1, establishing a layout space and performing grid processing on the layout space; S2, dividing the grid in the layout space into unfeasible areas, high-risk areas and low-risk areas according to the space planning in the cargo tank; S3, different risk information values are respectively given to the grids in the unfeasible region, the high-risk region and the low-risk region, the risk information value of the unfeasible region is greater than the risk information value of the low-risk region, and the risk information value of the high-risk region is between the risk information value of the unfeasible region and the risk information value of the low-risk region; S301, according to the spatial height of the grid, the height information value of the grid is calculated, and the height information value is positively correlated with the spatial height; S4, an evaluation function is set:

[0007] In the formula, L is the pipeline laying length, W is the number of pipeline elbows, and P is the risk avoidance degree; 、 、 is a weight parameter; The risk avoidance degree is calculated by the following formula:

[0008] In the formula, n is the number of grids occupied by the pipeline, is the risk information value of the grid i, is the height information value of the grid i; S5, in the high-risk region and the low-risk region, the optimal layout route is calculated by using a path planning algorithm with the minimum evaluation function as the target.

[0009] 3. Advantages Compared with the prior art, the advantages of the present application are: (1) The present application proposes a region type division, combines a node secondary diffusion search, and improves the risk avoidance degree of the algorithm calculation result for the cabin pipeline layout scheme to the engineering rules.

[0010] (2) The present application improves the search mechanism, adjusts the initial population position generation strategy, uses two different position updating methods to update the individual position in the population, improves the algorithm layout effect, and improves the probability of the feasible solution obtained by the population individuals.

[0011] (3) The present application increases the orthogonal operation, so that the calculated pipeline path is orthogonal, which meets the requirements of FLNG liquid cargo tank pipeline layout. DETAILED DESCRIPTION

[0012] Figure 1 It is a layout space division schematic diagram of a FLNG liquid cargo tank pipeline automatic layout method; Figure 2 It is a secondary diffusion schematic diagram of a FLNG liquid cargo tank pipeline automatic layout method; Figure 3It is a simulation effect diagram of a FLNG liquid cargo tank pipeline automatic layout method. DETAILED DESCRIPTION

[0013] The technical solutions of the present application will be described clearly and completely below in combination with the drawings.

[0014] Please refer to Figures 1 to 3 , the present application provides a FLNG liquid cargo tank pipeline automatic layout method, comprising the following steps: S1, establish a layout space, and grid the layout space; S2, according to the space planning in the cargo tank, the grid in the layout space is divided into unfeasible area, high-risk area and low-risk area; S3, the grid in the unfeasible area, high-risk area and low-risk area is respectively given different risk information value, the risk information value of the unfeasible area is greater than the risk information value of the low-risk area, the risk information value of the high-risk area is between the risk information value of the unfeasible area and the risk information value of the low-risk area; S301, according to the space height of the grid, the height information value of the grid is calculated, the height information value is positively correlated with the space height; S4, set evaluation function:

[0015] In the formula, L is the pipeline laying length; W is the number of pipe elbows; P is the risk avoidance degree; 、 、 is the weight parameter; The risk avoidance degree is calculated by the following formula:

[0016] In the formula, n is the number of grids occupied by the pipeline, is the risk information value of grid i, is the height information value of grid i; S5, in the high-risk area and the low-risk area, the optimal layout route is calculated by using path planning algorithm with the minimum evaluation function as the target.

[0017] In S1, the grid description precision is determined according to the inner diameter size of the pipeline to be arranged, and the ratio between the grid description precision and the actual layout space size in the cargo hold, the grid description precision being greater than the inner diameter size of the pipeline to be arranged; preferably, a Cartesian coordinate system is established in the liquid cargo hold. Usually, the lower left corner point of the layout space of the liquid cargo hold is taken as the coordinate origin, the directions parallel to the three edges of the liquid cargo hold are taken as the positive directions of the X, Y and Z axes respectively, so as to ensure that all the equipment in the hold and the subsequent containment boxes are positioned and sized in a unified coordinate system; and the inner diameter size of the pipeline to be arranged is taken as the grid description precision.

[0018] Preferably, the ratio between the grid description precision and the actual layout space size in the cargo hold is set to 1:300 mm, and the layout space is divided into 20*20*20 grids.

[0019] The grid can be calculated by the following formula to realize the mutual conversion between the number and the space coordinates:

[0020] In the formula, n is the grid serial number identifier; nx, ny and nz are the coordinate values corresponding to the grid respectively; mod is the remainder function; and ceil is the upward rounding function.

[0021] In S2, the risk information value of the grid in the unfeasible area is 2, the risk information value of the grid in the high-risk area is 1.5, and the risk information value of the grid in the low-risk area is 0.

[0022] Preferably, the high-risk area includes an area adjacent to the grids where the high-pressure, low-temperature and high-temperature equipment are located, and the width of the area is two grid lengths. The unfeasible area includes the grids where the equipment in the cargo hold is located, the grids where the equipment in the cargo hold is located are calculated by the containment box method, and the unfeasible area further includes the grids where the personnel passageway and the electrical equipment are located, as shown in Figure 1

[0023] The containment box method takes the lower left corner point of the equipment as the boundary point coordinate, constructs a cuboid containment box parallel to the coordinate axes, takes the minimum coordinates and the maximum coordinates xmin, ymin, zmin, xmax, ymax and zmax of the equipment on the X, Y and Z axes respectively to determine the shape and position of the entire containment box, thereby completing the preliminary simplified description of the equipment.

[0024] In step S301, the height information value is calculated by the following formula:

[0025] In the formula, e is the natural logarithm, i is the current layer number of the grid, high is the total number of layers in the layout space in the height direction, and H is the height information value.​

[0026] In S4, the weight parameters are as follows: =1, =1, =1.5; The evaluation function can cover three key indicators: pipeline laying length, number of pipeline elbows, and risk avoidance achievement, to achieve accurate evaluation and screening of FLNG liquid cargo tank pipeline layout plans to obtain the optimal solution.

[0027] In S5, the path planning algorithm is a gray wolf optimization algorithm, and the gray wolf optimization algorithm includes the following steps: A1. Set the population size, number of iterations, and pipeline nodes; A2. Use random search to generate the positions of individuals in the wolf pack: ; ; Where z rand is a random number with a value of [0, 1] generated by the Sine chaotic map, lb is the lower limit of the layout space; ub is the upper limit of the layout space; A3. Use the following formula to update the position of individuals in the wolf pack:

[0028]

[0029]

[0030] Where, , and These are the positions of the Alpha wolf, Beta wolf, and Delta wolf respectively. The evaluation function value corresponding to the position of the Alpha wolf is the smallest, and the evaluation function values ​​corresponding to the positions of the Alpha wolf, Beta wolf, and Delta wolf increase in turn. , and are the distances between the other wolves in the pack and the Alpha, Beta, and Delta wolves, respectively. is the individual's position before updating, Updated position for the individual; A4 For the wolf individuals whose updated positions fall within the grid of the infeasible area, the grid in the nearest high-risk area or low-risk area is used as their updated position, such as Figure 2 As shown; A5, repeat A3 and A4 until a specified number of iterations is reached, and generate the pipeline path according to the position of the individual that minimizes the evaluation function value.

[0031] In A1, the population size can be set to 5, the number of iterations can be set to 20, and the number of pipeline nodes can be set to 3, In order to increase the search efficiency and avoid falling into local optimum, the position of the new individual can be generated by referring to the position and number of individuals in the wolf pack in step A2, and the number of wolf packs can be expanded; preferably, the number of generated individuals is the same as the number of individuals in the wolf pack in step A2, which is 5, and the following steps can be used to achieve this: A201, the following formula is used to calculate the position of the specified number of individuals for expanding the number of wolf packs;

[0032] In the formula, is the position of the optimal individual in the wolf pack generated in step A2, which minimizes the evaluation function value, k is a random number in [-1, 1], is the upper limit of the position of the wolf pack generated in step A2, is the lower limit of the position of the wolf pack generated in step A2; If the position of the individual calculated in step A201 is located in an infeasible region, the following formula is used to regenerate it:

[0033] where rand() is a random number between 0 and 1.

[0034] In nature, the hunting behavior of wolf packs exhibits high cooperation and strategy. Especially the key link of surrounding prey is an important prelude to the successful capture of food by wolf packs. In the hunting behavior of wolf packs, the wolf pack will first surround the prey, so the position of the individual in the wolf pack can be updated in step A3 to gradually approach the prey.

[0035] In order to further increase the search ability of the gray wolf optimization algorithm, the following formula is used to update the position of the individual generated in step A201:

[0036]

[0037] In the formula, is the position before updating, is the position after updating, r max , r min is a control parameter, respectively 0.9, 0.2, and T is the maximum number of iterations.

[0038] In this way, the position of the individual generated by step A201 is updated, which can keep the position of the individual generated by step A201 always around the wolf pack, so as to find new prey and avoid the algorithm falling into a local optimal solution.

[0039] In A5, the pipeline path is generated by an orthogonalization operation, and the final result is as shown in Figure 3 Figure 3 The bending angles of the pipeline paths shown in A5 and A6 are all 90 degrees, which meets the requirements of the FLNG liquid cargo tank pipeline layout.​

Claims

1. A method for automatically laying out FLNG cargo tank piping, characterized by: The following steps are involved: S1. Establish a layout space and rasterize the layout space; S2. Divide the grid in the layout space into an infeasible area, a high-risk area, and a low-risk area according to the space planning in the cargo hold; S3. Assign different risk information values ​​to the grids in the infeasible area, the high-risk area, and the low-risk area, respectively. The risk information value of the infeasible area is greater than the risk information value of the low-risk area, and the risk information value of the high-risk area is between the risk information value of the infeasible area and the risk information value of the low-risk area. S301, calculating a height information value of the grid according to the spatial height of the grid, wherein the height information value is positively correlated with the spatial height; S4. Set the evaluation function: Where, L is the length of pipeline laying; W is the number of pipeline elbows; P is the degree of risk avoidance; 、 、 is the weight parameter; The safe haven achievement is calculated using the following formula: Where n is the number of grids occupied by the pipeline, is the risk information value of grid i, is the height information value of grid i; S5. In high-risk areas and low-risk areas, the path planning algorithm is used to calculate the optimal layout route with the goal of minimizing the evaluation function.

2. The FLNG cargo tank piping automatic layout method according to claim 1, characterized in that: In S1, the grid description accuracy and the ratio between the grid description accuracy and the actual layout space size in the cargo hold are determined according to the inner diameter size of the pipeline to be laid, and the grid description accuracy is greater than the inner diameter size of the pipeline to be laid.

3. The FLNG cargo tank piping automatic layout method according to claim 1, characterized in that: The risk information value of the grid in the infeasible area is 2, the risk information value of the grid in the high-risk area is 1.5, and the risk information value of the grid in the low-risk area is 0.

4. The method for automatically laying out FLNG cargo tank piping according to claim 1, characterized in that: The high-risk area includes an area adjacent to the grids where high-pressure, low-temperature and high-temperature equipment are located and has a width of two grid lengths.

5. The FLNG cargo tank piping automatic layout method according to claim 1, characterized in that: The infeasible area includes the grid where the equipment in the cargo hold is located, and the grid where the equipment in the cargo hold is located is calculated using the box packing method.

6. The FLNG cargo tank piping automatic layout method according to claim 1, characterized in that: The path planning algorithm is a gray wolf optimization algorithm, which includes the following steps: A1. Set the population size, number of iterations, and pipeline nodes; A2. Use random search to generate the positions of individuals in the wolf pack: ； ； Where z rand is a random number with a value of [0, 1] generated by the Sine chaotic map, lb is the lower limit of the layout space; ub is the upper limit of the layout space; A3. Use the following formula to update the position of individuals in the wolf pack: Where, , and These are the positions of the Alpha wolf, Beta wolf, and Delta wolf respectively. The evaluation function value corresponding to the position of the Alpha wolf is the smallest, and the evaluation function values ​​corresponding to the positions of the Alpha wolf, Beta wolf, and Delta wolf increase in turn. , and are the distances between the other wolves in the pack and the Alpha, Beta, and Delta wolves, respectively. is the individual's position before updating, Updated position for the individual; A4. For each wolf whose updated position falls within a cell in the infeasible area, the cell in the nearest high-risk area or low-risk area is used as its updated position. A5. Repeat A3 and A4 until the specified number of iterations is reached, and generate a pipeline path based on the individual position that minimizes the evaluation function value.

7. The FLNG cargo tank piping automatic layout method according to claim 6, characterized in that: Said A2 further comprises the following steps: A201. Use the following formula to calculate the locations of a specified number of individuals to expand the wolf pack. Where, is the position of the best individual in the wolf pack generated in step A2, which minimizes the evaluation function value, and k is a random number in the range [-1, 1]. is the upper limit of the wolf pack positions generated in step A2, is the lower limit of the wolf pack positions generated in step A2; If the individual position calculated in step A201 is within the infeasible region, it is regenerated using the following formula: Among them, rand() is a random number between 0 and 1.

8. The FLNG cargo tank piping automatic layout method according to claim 7, characterized in that: In A3, the position of the individual generated in step A201 is updated using the following formula: Where, is the position before updating, is the updated position, r max 、r min are control parameters, which are set to 0.9 and 0.2 respectively, and T is the maximum number of iterations.

9. The method for automatically laying out FLNG cargo tank piping according to claim 6, characterized in that: In A5, the pipeline path is generated by using an orthogonalization operation.

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