CN105335586B - Method for establishing automatic cloth tube model in design of heat exchanger - Google Patents

Abstract

The invention discloses a method for establishing an automatic pipe layout model in the design of a heat exchanger. According to the obtained basic data of the heat exchanger, the parameters required for the pipe layout are determined, and the vertical distance from the center of the heat exchanger to the partition groove is calculated; According to whether the grid is continuous, calculate the position of the partition slot; build a preliminary pipe layout model, and abstract the corresponding mathematical model according to the different arrangement forms of heat exchange tubes. Pipes are arranged according to the abstracted data model; the preliminary pipe layout model is automatically checked and adjusted to obtain the optimal structure, and the established optimal general automatic pipe layout model is output. The method of the present invention is simple in operation, simple in algorithm, and strong in versatility. Based on the method of combining numerical analysis and geometric figures, a general automatic pipe layout model from low pipe to high pipe is built, and infinite fitting optimization is performed, which greatly improves the pipe layout. tube accuracy.

Description

The Method for Establishing Automatic Piping Model in Heat Exchanger Design

technical field

The invention relates to the field of computer-aided design of chemical engineering, in particular to a design method for establishing an automatic pipe layout model in the design of heat exchangers. According to the basic parameters of the heat exchanger, heat exchangers for floating head type, fixed tube sheet type and U-shaped tube type are obtained. Auto-routing model for low-to-high-level piping design of the machine.

Background technique

In the petrochemical industry, heat exchangers are commonly used energy exchange equipment. In the design process of the heat exchanger, the arrangement of the heat exchange tubes is a relatively important link. The accuracy of the tube arrangement directly determines the heat exchange effect of the heat exchanger. The establishment of baffles and support plates is also closely related to the arrangement of tubes. The arrangement of pipes is a very cumbersome work. Designers often arrange pipes manually based on experience. First, they estimate the pipe arrangement according to empirical values, and then perform multiple trial calculations and make modifications to the drawings, especially when laying out pipes for high-profile , it is easy to cause large errors and greatly reduce the accuracy. Therefore, this traditional design mode is labor-intensive, time-consuming, and less accurate.

In the heat exchanger piping design, after searching the existing literature, it is found that the model design for the piping layout in the existing literature is not accurate and simple enough, does not consider the discontinuity of the grid, and after the piping layout Basically, the close relationship between tube arrangement and baffles and support plates is not considered.

Contents of the invention

In order to solve the deficiencies in the prior art, the present invention discloses a method for establishing an automatic pipe layout model in heat exchanger design. The present invention proposes a method for the design of heat exchangers for grid continuity and grid discontinuity. The method of establishing an automatic pipe layout model, which is based on the combination of numerical analysis and geometric graphics, builds a general automatic pipe layout model from low to high pipes, and performs infinite fitting optimization, programming on the software development platform through c++ Realize the transformation from the preliminary piping model to the precise piping model, realize the reconstruction of the piping model, and obtain the optimal piping model. After the pipe layout model is established, the baffle plate and support plate are established according to the pipe layout effect. The cut edge of the baffle plate passes through the center of the pipe, and the support plate calculates the octagon and hexagon passing through the pipe center according to the pipe arrangement form.

To achieve the above object, the specific scheme of the present invention is as follows:

The method for establishing an automatic pipe layout model in heat exchanger design includes the following steps:

According to the obtained basic data of the heat exchanger, determine the parameters required for pipe layout, and calculate the vertical distance from the center of the heat exchanger tube sheet to the partition groove;

According to whether the grid is continuous or not, calculate the position of the partition slot. When the grid is continuous, the entire mesh pipe is laid out, and the pipe is placed on the entire tube sheet in one pass. After the pipe is laid, the position of the partition slot is calculated. Add the corresponding vertical distance from the center of the tube sheet to the vertical distance from the center of the tube plate of the heater to the partition slot, and then find the starting position of the partition slot, and then determine the position of the partition slot according to the width of the partition slot, and calculate Find the area of the partition groove at the split-pass of a single tube sheet, and then sum the area of the single partition groove to obtain the area of the partition groove at all split-pass;

When the grid is discontinuous, divide the tube sheet into separate pipes. First, get the area of the partition groove according to the calculated vertical distance from the center to the partition groove. After removing the covered area of the partition groove, then distribute the pipes separately ;

Build a preliminary pipe layout model, abstract the corresponding mathematical model according to different arrangements of heat exchange tubes, and arrange the pipes in the quadrants covered by the tubes according to the abstracted data model according to the characteristics of the selected split-pass arrangement form;

The preliminary piping model is automatically checked and adjusted to obtain the optimal structure, and the established optimal general automatic piping model is output.

Further, the basic data of the heat exchanger includes the inner diameter of the shell, the diameter of the heat exchange tube, the number of tube passes, the arrangement form of the heat exchange tube, the arrangement form of the split pass, the width of the separator groove, and the center-to-center distance between the two sides of the separator groove.

Furthermore, when the grid is continuous, according to the principle that the area of each tube is approximately equal, the total area of the limited circle of the tube is subtracted from the area lost by the partition groove to evenly distribute each tube. At the same time, the number of tubes, The partition layout form and partition slot data have been determined. The vertical distance from the center of the heat exchanger tube sheet to the partition slot is calculated by solving the equation with the dichotomy method, and the position of the partition slot is further determined.

Furthermore, when the grid is discontinuous, pipes are arranged according to each basic shape and combined figure when laying out separate pipes. The basic shape is divided into two types: rectangle and trapezoid. The combined figure is a combination of the two basic shapes. The basic properties only involve Combining graphics to single-quadrant ones mainly involves graphics that span quadrants.

Further, a preliminary pipe layout model is built: in the calculation, the combination of numerical analysis and geometric graphics characteristics is used to deal with different heat exchange tube arrangements and split-pass layouts, such as square arrangement, square arrangement, triangular arrangement and equilateral triangle arrangement. These four arrangements have different geometric characteristics. According to these four geometric characteristics, the mathematical model is abstracted; according to the characteristics of the selected split-range arrangement, the pipes are arranged in the quadrants covered by the tubes according to the abstracted data model. .

Further, the actual headspace height and bottom space height are calculated according to the preliminary tube arrangement results. The actual headspace height refers to the distance from the outer wall of the top row of heat exchange tubes to the top of the shell, and the actual bottom space height refers to The most important thing is the distance from the outer wall of the bottom row of heat exchange tubes to the bottom of the shell. At the same time, the position of the tie rod and the position of the gear tube are accurately set in the tube layout area according to the requirements, and the preliminary tube layout model is built.

Further, the pipe layout model is automatically checked and adjusted to obtain the optimal structure. From the obtained preliminary pipe layout model, the current pipe layout error of each pipe pass is calculated, and then the parameters are adjusted by a step, and the adjusted error is compared with the adjusted For the previous error value, judge whether it is in the rising range or the falling range. When it is in the rising range, reduce the step size. When it is in the falling range, increase the step size. Use the infinite fitting optimal result method until you find the rising range and the optimal solution between the descending intervals.

Further, establish appropriate baffles and support plates based on the adjusted piping model: according to the output piping model, create baffles and automatically adjust them so that the cut edges of the baffles pass through the center of the pipe; create support plates , automatically adjusted according to the arrangement of the pipes: when the support plate is a square or turn into a square, calculate the octagon in which all sides of the support plate pass through the center of the pipe according to the flow area of the baffle; , calculate the hexagon in which each side of the support plate passes through the center of the tube, and this support plate plays the role of baffle and support.

Further, the output pipe layout model is used for the pipe layout from low to high strokes of floating head type, fixed tube sheet type and U-shaped tube heat exchangers.

Beneficial effects of the present invention:

The method of the present invention is simple in operation, simple in algorithm, and strong in versatility. Based on the combination of numerical analysis and geometric figures, a general automatic pipe layout model from low pipe to high pipe is built, and infinite fitting optimization is carried out, which greatly improves the pipe layout. tube accuracy. It solves the problems of high labor intensity and low accuracy in the current traditional pipe layout mode, and can well meet various pipe layout requirements in heat exchanger design.

The optimal universal automatic pipe layout model output and established by the present invention is the obtained optimal pipe layout model, and the pipe layout is carried out based on the optimal result to improve the structural stability and heat exchange efficiency of the heat exchanger design.

Description of drawings

Figure 1 Basic steps to find the optimal solution;

Fig. 2 Explanatory diagram of trimming octagon of support plate;

Figure 3 is a flow chart of obtaining the optimal pipe layout model;

Fig. 4 is a schematic diagram of the overall flow of the present invention.

Detailed ways:

The present invention is described in detail below in conjunction with accompanying drawing:

As shown in Figure 4, on the basis of the design surface model of the heat exchanger piping layout, according to the basic information of the piping layout in the heat exchanger design, the parameters required for the piping layout are determined through the combination of numerical analysis and geometric figures; according to whether the grid is Continuously, calculate the position of the partition slot; initially build the pipe layout model; the preliminary pipe layout model is automatically checked and adjusted to obtain the optimal structure. According to the pipe layout effect, the baffle and the support plate are established, and the cutting edge of the baffle is automatically adjusted to pass through the center of the pipe. The support plate calculates the octagon and hexagon passing through the pipe center according to the pipe arrangement form. The method has the advantages of simple operation, simple algorithm, strong versatility, and high accuracy, and can well meet various pipe layout requirements in heat exchanger design.

A more detailed implementation example:

Step 1. The user enters basic information through the interactive operation area of the interface area, including the inner diameter of the shell, the diameter of the heat exchange tube, the number of tube passes, the arrangement of the heat exchange tube, the layout of the split pass, the width of the partition slot, and the tubes on both sides of the partition slot. Heart distance, etc.;

Step 2. According to the basic information of pipe layout obtained in step 1, calculate the important parameters in pipe layout. Implementation steps: In step 1, the basic information of user needs is obtained through user interaction, and the computer uses the dichotomy method based on these basic information Calculate the important parameters in the pipe layout, that is, the vertical distance from the center of the pipe to each partition slot, that is, the position of the side of the partition slot near the center. According to the principle that the pipe layout area of each tube pass is approximately equal, the layout The total area of the tube-defining circle minus the area lost by the partition groove is evenly distributed to each tube pass. The layout of the tubes in GB151 is fixed, and the geometric calculation is performed according to the layout of each tube. Here, the dichotomy method is used to solve the vertical distance of each partition groove. Due to the symmetry of the piping structure, it is only necessary to calculate one of the symmetrical partition slots, and store the calculated parameter data.

Step 3. According to whether the grid is continuous, calculate the position of the partition groove Implementation steps: the user sets whether the grid is continuous through the interface interaction operation. When the grid is discontinuous, the user needs to choose whether to route pipes in the center.

When the mesh is continuous, the computer carries out the whole mesh cloth pipe, and then performs split processing according to the basic parameters obtained in step 2. Mesh continuity refers to the entire mesh tube, all the one-way tube layout on the entire tube sheet, calculate the position of the partition groove after the tube layout, according to the obtained vertical distance from the center of the heat exchanger tube sheet to the partition groove, from the tube Add the corresponding vertical distance to the center of the plate, and then find the starting position of the partition groove, and then determine the position of the partition groove according to the width of the partition groove. Calculate the area of the partition groove according to the calculation method of the area of the tube-sheet split-pass in the latest version of GB151, and then sum the area of the single partition groove to obtain the area of the partition groove at all split-pass;

When the grid is discontinuous, calculate the diaphragm groove according to the basic parameters obtained in step 2, and remove the area covered by the current diaphragm groove and the distance between the tube centers on both sides of the diaphragm groove on the entire tube sheet.

After removing the covered area of the bulkhead slot, the pipes are distributed separately. When laying pipes individually, arrange pipes according to each basic shape and combined graphics. The basic shape is divided into two types: rectangle and trapezoid. A composite shape is a combination of two basic shapes. Basic shapes only involve single quadrants, and composite shapes mainly involve cross-quadrant shapes.

The actual pipe layout area is the remaining area after subtracting the area covered by the partition groove and the tube center distance on both sides of the partition groove from the pipe layout area within the limited circle of the pipe layout on the tube plate.

Step 4. The implementation steps of initially building the pipe layout model:

The user sets the split-pass layout form in the operation interface area. According to the geometric characteristics of the set split-pass layout form, the computer background calls the common mathematical model function, and builds the pipe layout model according to different parameters. Users can adjust the height of the top space and bottom space according to the needs in the interface operation area, and obtain the real top space and bottom space values after the model is built.

The user can set the tie rods and gear tubes in the graphic operation area according to the needs, and the computer background can directly obtain the precise position of the tie rods and gear tubes required by the customer, and create the tie rods and gear tubes.

Step 5. After establishing the preliminary model, calculate the average number of pipes according to the pipe data in the initial pipe layout model. The optimal solution is obtained by using the infinite fitting optimal result method. The basic steps are shown in Figure 1. From the preliminary general data model obtained in step (4), the current pipe layout error of each pipe is calculated, and then the parameters are adjusted by a step. Compare the adjusted error with the pre-adjusted error value to determine whether it is in the rising range or the falling range. When it is in the rising range, reduce it by one step, and when it is in the falling range, increase it by one step. Until the optimal solution located in the rising interval and the descending interval is found.

The computer performs the fitting operation in the background, and after adjusting the stride, iteratively calls the pipe layout function. Re-model, count the error of the current tube, calculate the error of the current tube, and compare and adjust until it approaches the optimal model infinitely. As shown in Figure 3, the optimal pipe layout model is obtained.

Step 6. After completing all piping modeling, output the optimal model of piping.

Step 7. Establish appropriate baffles and support plates based on the piping results. Considering that the settings of the baffles and support plates are closely related to the arrangement of the pipes, according to the output pipe layout model, the baffles are established and automatically adjusted so that the cut edges of the baffles pass through the center of the pipes. Create a support plate and automatically adjust it according to the arrangement of the pipes, as shown in Figure 2. When the pipe layout is square or converted to a square pipe, it is calculated according to the flow area of the baffle that each side of the support plate passes through the center of the pipe. Hexagonal shape, when it is arranged in a triangle or turned into a regular triangle, calculate the hexagon in which each side of the support plate passes through the center of the pipe, and this kind of support plate plays the role of baffle and support.

Users can set the basic parameters of baffles and support plates in the interface operation area. The computer background automatically cuts the edge to set the baffle and support plate. At the same time, users are allowed to adjust the edge trimming in the graphic operation area according to special needs.

Although the specific implementation of the present invention has been described above in conjunction with the accompanying drawings, it does not limit the protection scope of the present invention. Those skilled in the art should understand that on the basis of the technical solution of the present invention, those skilled in the art do not need to pay creative work Various modifications or variations that can be made are still within the protection scope of the present invention.

Claims (9)

1. The method for establishing an automatic pipe layout model in heat exchanger design is characterized in that it comprises the following steps: According to the obtained basic data of the heat exchanger, determine the parameters required for pipe layout, and calculate the vertical distance from the center of the heat exchanger tube sheet to the partition groove; According to whether the grid is continuous or not, calculate the position of the partition slot. When the grid is continuous, the entire mesh pipe is laid out, and the pipe is placed on the entire tube sheet in one pass. After the pipe is laid, the position of the partition slot is calculated. Add the corresponding vertical distance from the center of the tube sheet to the vertical distance from the center of the tube plate of the heater to the partition slot, and then find the starting position of the partition slot, and then determine the position of the partition slot according to the width of the partition slot, and calculate Find the area of the partition groove at the split-pass of a single tube sheet, and then sum the area of the single partition groove to obtain the area of the partition groove at all split-pass; When the grid is discontinuous, the tube sheet is divided into pipes, first, according to the calculated vertical distance from the center to the partition slot, the area of the partition slot is obtained, and the current partition slot and both sides of the partition slot are removed on the entire tube sheet After the area covered by the tube center distance, the tubes are distributed separately; Build a preliminary pipe layout model, abstract the corresponding mathematical model according to different arrangements of heat exchange tubes, and arrange the pipes in the quadrants covered by the tubes according to the abstracted data model according to the characteristics of the selected split-pass arrangement form; The preliminary piping model is automatically checked and adjusted to obtain the optimal structure, and the established optimal general automatic piping model is output. 2. The method for establishing an automatic pipe layout model in heat exchanger design as claimed in claim 1, wherein the basic data of the heat exchanger includes shell inner diameter, heat exchange tube diameter, number of tube passes, heat exchange tube Arrangement form, split-range layout form, width of partition plate slot and distance between tube centers on both sides of plate slot. 3. The method for establishing an automatic pipe layout model in heat exchanger design as claimed in claim 1, wherein when the grid is continuous, according to the principle that the pipe layout area of each tube pass is approximately equal, the pipe layout is limited After the total area of the circle is subtracted from the area lost by the partition slots, each tube pass is evenly distributed. At the same time, the number of tube passes, the layout of the sub-passes and the data of the partition slots are known. The vertical distance from the center of the heater tube plate to the partition groove further determines the position of the partition groove. 4. The method for establishing an automatic pipe layout model in heat exchanger design as claimed in claim 1, wherein when the grid is discontinuous, the pipes are arranged according to each basic shape and combined graphics when the separate pipes are distributed , the basic shape is divided into two types: rectangle and trapezoid. The combined figure is the combination of the two basic shapes. The basic shape only involves a single quadrant, and the combined figure mainly involves the cross-quadrant figure. 5. The method for establishing an automatic pipe layout model in heat exchanger design as claimed in claim 1, characterized in that, to build a preliminary pipe layout model: in the calculation, the combination of numerical analysis and geometric figure characteristics is used to process different The arrangement of heat exchange tubes and the layout of split-pass arrangements, the four arrangements of square arrangement, square arrangement, triangle arrangement and regular triangle arrangement have different geometric characteristics. According to these four geometric characteristics, a mathematical model is abstracted; According to the characteristics of the selected split-pass layout, the tubes are arranged in the quadrants covered by the tubes according to the abstracted data model. 6. The method for establishing an automatic pipe layout model in heat exchanger design as claimed in claim 5, wherein the actual headspace height and bottom space height are calculated according to the preliminary pipe layout results, and the actual headspace height It refers to the distance from the outer wall of the top row of heat exchange tubes to the top of the shell, and the actual height of the bottom space refers to the distance from the outer wall of the bottom row of heat exchange tubes to the bottom of the shell. In the pipe layout area, the position of the tie rod and the position of the file pipe are accurately set, and the preliminary pipe layout model is built. 7. The method for establishing an automatic pipe layout model in heat exchanger design as claimed in claim 1, wherein the pipe layout model is automatically checked and adjusted to obtain the optimal structure, and the obtained preliminary pipe layout model is statistically Find out the current pipe layout error of each tube pass, then adjust the parameters by a step, compare the adjusted error and the pre-adjusted error value, and judge whether it is in the rising range or the falling range. When it is in the rising range, reduce a step. When it is a descending interval, add a step, and use the infinite fitting optimal result method until the optimal solution between the ascending interval and the descending interval is found. 8. The method for establishing an automatic pipe layout model in heat exchanger design as claimed in claim 1, characterized in that, according to the adjusted pipe layout model, suitable baffles and support plates are established: according to the output layout Pipe model, create baffles and automatically adjust them so that the cut edge of the baffles passes through the center of the pipe; create support plates and automatically adjust according to the arrangement of the tubes: when the support plate is square and turns into a square pipe, the baffles The flow area is calculated by calculating the octagon in which all sides of the support plate pass through the center of the pipe; when arranged in a triangle or regular triangle, calculate the hexagon in which each side of the support plate passes through the center of the pipe. This kind of support plate plays a role in baffle and support role. 9. The method for establishing an automatic pipe layout model in heat exchanger design according to any one of claims 1-8, wherein the output pipe layout model is used for floating head type, fixed tube sheet type and U-type Tube heat exchanger from low to high pipe layout.