A method for controlling the temperature of the tube side of a heat exchanger with constant temperature of the mother tube

Abstract

This invention provides a method for controlling the tube-side temperature of a heat exchanger with a constant mother tube temperature. The heat exchanger includes a tube side and a shell side, and heat exchange occurs between the tube-side fluid and the shell-side fluid. The tube side includes a tube inlet and a tube outlet, and the tube side includes a shell. The shell side includes heat exchange tubes disposed within the shell. The mother tube temperature remains constant. The method for controlling the tube-side outlet temperature of the heat exchanger mainly includes steps 1)-3). This invention achieves rapid control of the tube-side temperature of the heat exchanger by quickly locating the two inlet valves that need to be opened and then adjusting the opening and closing of the two adjacent inlet valves to quickly reach the predetermined temperature.

Description

Technical Field

[0001] This invention relates to a shell-and-tube heat exchanger, and more particularly to a method for controlling the tube-side temperature of a heat exchanger with a constant main tube temperature. Background Technology

[0002] Shell-and-tube heat exchangers are widely used in industries such as chemical, petroleum, refrigeration, nuclear power, and energy. Due to the global energy crisis, the demand for heat exchangers in industrial production is increasing, and the quality requirements for heat exchangers are also becoming more stringent. In recent decades, although compact heat exchangers (plate, plate-fin, and welded plate heat exchangers, etc.), heat pipe heat exchangers, and direct contact heat exchangers have developed rapidly, shell-and-tube heat exchangers still dominate in terms of production and usage due to their high reliability and wide adaptability. According to relevant statistics, shell-and-tube heat exchangers still account for about 70% of all heat exchangers used in industrial plants.

[0003] Shell-and-tube heat exchangers used for heat exchange with hot and cold fluids present several problems when employing a conventional structure with only one tube inlet and outlet. Firstly, because the heat exchange area of ​​the tube bundle within a conventional shell-and-tube heat exchanger is essentially fixed, controlling the temperature of the heat exchange medium at the tube outlet is difficult, especially given constant temperatures and flow rates at both the shell-side and tube-side inlets. Secondly, if the temperature of the heat or cold source is too high or too low, the heat exchanger is prone to temperature instability, significantly impacting its lifespan.

[0004] However, traditional heat exchangers also suffer from the aforementioned problems, and their development has been greatly limited under the new circumstances of energy conservation and emission reduction. Therefore, to address these shortcomings, a shell-and-tube heat exchanger with a simple structure has been developed. By setting up multiple shells and headers, multiple tube passes are formed, which can dynamically adjust the output temperature of the heat exchanger tube passes, thereby effectively improving both the heat exchange area and heat exchange efficiency. This is of great significance for industrial production and energy conservation and emission reduction.

[0005] Currently, the determination of tube side temperature generally relies on flow rate changes. This invention provides a method for quickly and accurately locating the tube side output temperature while ensuring stable flow rate. Summary of the Invention

[0006] To overcome the defects and shortcomings of the existing technology, the present invention provides a heat exchanger tube-side temperature control method with constant mother tube temperature. By setting multiple tube-side inlets and controlling the fluid flow at different positions through inlet valves, the tube-side outlet temperature can be intelligently adjusted. At the same time, it provides a method to quickly and accurately locate the tube-side output temperature.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] A method for controlling the tube-side temperature of a heat exchanger with a constant main tube temperature, wherein the heat exchanger includes a tube side and a shell side, and heat exchange occurs between the tube-side fluid and the shell-side fluid; the tube side includes a tube inlet and a tube outlet, the tube side includes a shell, and the shell side includes heat exchange tubes disposed within the shell, the main tube temperature remains constant, and the control method for controlling the tube-side outlet temperature of the heat exchanger mainly includes the following steps:

[0009] Preferably, one inlet valve is opened to its maximum opening, while all other inlet valves are closed. The output temperature is detected, and the temperature data and inlet valve data are stored in a second database to obtain the output temperature of the tube when each inlet valve is opened to its maximum opening.

[0010] Preferably, the user sets the tube output temperature T, and the controller automatically retrieves data from the second database based on the set output temperature T. If the temperature T is equal to the tube output temperature when a certain inlet valve is opened to its maximum opening, then the controller controls that inlet valve to open and the other inlet valves to close.

[0011] Preferably, if the database does not find the output temperature of the tube when a certain inlet valve is opened to its maximum degree, then the data Tg and Td of the two adjacent inlet valves, namely the high temperature inlet valve and the low temperature inlet valve, are found when they are opened to their maximum degree, requiring Tg>T>Td. Then, the output temperature is adjusted by adjusting the opening degree of the two inlet valves.

[0012] Preferably, when the detected output temperature is higher than the predetermined temperature, the opening of the low-temperature inlet valve is increased and the opening of the high-temperature inlet valve is decreased.

[0013] Preferably, when the detected output temperature is lower than the predetermined temperature, the opening degree of the low-temperature inlet valve is reduced and the opening degree of the high-temperature inlet valve is increased.

[0014] Preferably, the shell includes multiple sub-shells, and the heat exchanger also includes multiple headers, with a sub-shell disposed between two adjacent headers. The heat exchange tubes are connected to the tube sheets in the adjacent headers. Each header is provided with a tube-side inlet or outlet, wherein there is one tube-side outlet, which is disposed on the outermost header, and the remaining headers are provided with tube-side inlets. The heat exchanger also includes a main pipe, which is connected to the tube-side inlet pipe, and the tube-side inlet pipe is connected to the tube-side inlet. The tube-side inlet pipes are in parallel, and each tube-side inlet pipe is provided with an inlet valve.

[0015] Preferably, it also includes a controller, which is connected to the inlet valve via data connection. The pipe outlet is also equipped with a pipe outlet temperature sensor. The controller controls the opening and closing of each inlet valve and the degree of opening based on the temperature detected by the pipe outlet temperature sensor.

[0016] Preferably, one inlet valve is opened to its maximum opening, while all other inlet valves are closed. The temperature of the main pipe and the output temperature of the pipe side are detected, and the temperature data and inlet valve data are stored in a second database to obtain the output temperature when each inlet valve is opened to its maximum opening.

[0017] Preferably, the controller automatically retrieves data from the second database based on the set outlet temperature T of the pipe and the detected temperature of the main pipe. If the output temperature of a certain inlet valve when it is opened to its maximum degree is equal to the set temperature, then that inlet valve is opened directly to its maximum degree. Otherwise, the controller finds the data of the two adjacent inlet valves, namely the high-temperature inlet valve and the low-temperature inlet valve, when they are opened to their maximum degree. Among the data where the output temperature of the high-temperature inlet valve is higher than the set temperature but has the smallest difference, and among the data where the output temperature of the low-temperature inlet valve is lower than the set temperature but has the smallest difference, the controller adjusts the opening degree of the two inlet valves to adjust the output temperature.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] This invention, by setting up multiple headers and sub-shells, quickly locates the two inlet valves that need to be opened, and then adjusts the opening and closing of the two adjacent inlet valves to make the output temperature quickly reach the predetermined temperature. This achieves rapid control of the tube-side temperature of the heat exchanger with a constant main tube temperature, thereby enabling accurate control of the temperature of the fluid output from the tube side, improving the control speed of the output fluid temperature, and realizing intelligent control of the output temperature. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the heat exchanger of the present invention. Detailed Implementation

[0021] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0022] The directional terms used in this article, such as up, down, left, and right, are used to indicate the relative positional relationship between the various components and do not represent their actual installation locations.

[0023] Figure 1 The heat exchanger of this application is disclosed. For example... Figure 1As shown, a heat exchanger for intelligently regulating tube-side temperature includes a tube side and a shell side, with heat exchange occurring between the tube-side fluid and the shell-side fluid. The tube side includes a tube-side inlet 1 and a tube-side outlet 2, and the tube side includes a shell. The shell side includes heat exchange tubes 3, which are disposed within the shell. The shell includes multiple sub-shells 4, and the heat exchanger also includes multiple headers 5, with a sub-shell 4 disposed between two adjacent headers. Each header is equipped with a tube sheet 6, and the heat exchange tubes 3 are connected to the tube sheets 6 in adjacent headers 5. Each header 5 has either a tube-side inlet 1 or a tube-side outlet 2, with only one tube-side outlet 2 located on the outermost header, for example... Figure 1 The heat exchanger is located on the left side. All other headers are equipped with tube-side inlets 1. The heat exchanger also includes a main pipe 7, which connects to tube-side inlet pipes 8. The tube-side inlet pipes 8 are connected in parallel, and each tube-side inlet pipe 8 is equipped with an inlet valve 11. Adjacent sub-shells are interconnected, preferably via connecting pipes 12.

[0024] This invention sets up multiple headers and sub-shells, with a tube-side inlet on each header. The multiple inlets are arranged along the fluid flow direction of the shell, so that the heat exchange of the tube-side fluid at different inlets is different. By controlling the fluid flow rate at each tube-side inlet, the temperature of the fluid output from the tube-side can be accurately controlled, improving the control speed of the output fluid temperature and realizing intelligent control of the output temperature.

[0025] As an improvement, the connecting pipe 12 can be installed inside the header, preferably inside the header. Figure 1 The lower part of the header. Enables communication between two adjacent sub-shells.

[0026] As an improvement, the connecting pipe 12 can be located externally, with adjacent sub-shells connected via an external connecting pipe. For example, both ends of the connecting pipe can be connected to the bottom of adjacent sub-shells, thus achieving communication between the two sub-shells.

[0027] An improvement, such as Figure 1 As shown, the shell-side inlet and outlet are located on the two sub-shells furthest apart. This arrangement maximizes the flow path of the shell-side fluid.

[0028] An improvement, such as Figure 1 As shown, the heat exchanger is a horizontal heat exchanger. The tube-side outlet 2 is located on the leftmost header, the shell-side inlet 9 is located on the left sub-shell, and the shell-side outlet 10 is located on the rightmost sub-shell. This arrangement causes the tube-side and shell-side fluids to flow in a counter-current manner, thereby further enhancing heat transfer.

[0029] Baffles are installed inside the shell to ensure that fluid flows through the entire shell side, preventing short-circuiting problems. The heat exchange tubes pass through the baffles.

[0030] As an improvement, within the sub-shell, the tube-side and shell-side flow is counter-current. Along the flow direction of the fluid within the sub-shell, the spacing of the baffles initially increases, then decreases from the middle of the sub-shell. Because the heat transfer per unit length along the fluid flow path is relatively uniform during counter-current flow, the overall heat transfer effect is optimal. However, experiments and simulations revealed that the heat transfer in the middle is significantly greater than that at the shell-side inlet and outlet. Therefore, by varying the baffle spacing, the heat transfer area between the shell-side and tube-side fluids within the baffles also changes. This area variation compensates for the uneven heat transfer, thereby further improving heat transfer efficiency. This invention treats each shell as a separate, small shell-and-tube heat exchanger for heat exchange design.

[0031] As an improvement, the spacing of the baffles increases progressively along the flow direction of the fluid within the sub-shell. Then, starting from the middle of the sub-shell, the spacing of the baffles decreases progressively. This variation in spacing makes the heat transfer per unit length of the fluid flow more uniform, further improving heat transfer efficiency.

[0032] The baffles are arranged vertically, including an upper baffle and a lower baffle, with the upper and lower baffles spaced apart. Along the flow direction of the fluid inside the sub-shell, the height of the lower baffle extending upward from the inner wall of the bottom tube gradually increases, while the length of the upper baffle extending downward from the inner wall of the upper tube gradually decreases.

[0033] During the research, it was found that the baffles in traditional heat exchangers exhibit uneven heat transfer across their cross-sections along the fluid flow direction. As the distance from the inlet increases, the density of the heat-exchange liquid at the bottom of the tubes increases, causing the liquid to flow downwards and significantly increasing the amount of heat-exchange liquid at the bottom. Therefore, an improved heat exchange structure is needed. This invention, with varying heights of the upper and lower baffles along the fluid flow direction, causes the liquid within the sub-shell to gradually move towards the center. This enhances heat transfer around the tubes at the shell center, changing the traditional heat transfer method, improving heat transfer efficiency at different locations, and resulting in more uniform heat transfer overall, further achieving the goal of enhanced heat transfer.

[0034] As an improvement, along the flow direction of the fluid inside the sub-shell, the vertical extension height of the lower baffle from the inner wall of the bottom tube gradually increases, while the vertical extension length of the upper baffle from the inner wall of the upper tube gradually decreases. These variations in amplitude further enhance overall heat transfer uniformity, thereby strengthening the heat transfer process.

[0035] An improvement is that the tube outlet is located at the lower end of the header, and the tube outlet is located at the upper end of the header.

[0036] One improvement is that the shell-side outlet is located at the lower end of the subshell, and the shell-side inlet is located at the upper end of the subshell.

[0037] When a single inlet valve is open and the other inlet valves are closed, the tube-side output temperature gradually increases or decreases along the flow direction of the fluid in the shell side. For example, when the tube side is a heat source, from left to right, the tube-side output temperature gradually decreases as different valves are opened individually; when the tube side is a cold source, from left to right, the tube-side output temperature gradually increases as different valves are opened individually.

[0038] The shell-side fluid enters from the leftmost inlet 9, then enters the shell, exchanges heat with the fluid in the heat exchange tube 3 inside the shell, and then flows out from the rightmost outlet 10, completing the heat exchange with the tube-side fluid.

[0039] Preferably, the heat exchanger also includes a controller, which is data-connected to the inlet valve 11. A tube-side outlet temperature sensor is also provided at the tube-side outlet to detect the fluid temperature output from the tube-side outlet. The controller is data-connected to the tube-side outlet temperature sensor. Based on the temperature detected by the tube-side outlet temperature sensor, the controller controls each inlet valve 11 to perform the following operations: opening the inlet valve 11, closing the inlet valve 11, and adjusting the opening degree of the inlet valve 11.

[0040] Preferably, the system includes a main pipe 7, which connects to each inlet 1 of the pipe side, and the pipes of each inlet 1 are connected in parallel. The main pipe 7 is equipped with a main pipe temperature sensor to detect the temperature of the fluid entering each inlet. The controller is connected to the main pipe temperature sensor. The controller stores the temperature data detected by the pipe side outlet temperature sensor, the temperature data detected by the main pipe temperature sensor, and the opening and closing status and degree of each inlet valve in a first database. Therefore, the first database stores multiple historical data sets.

[0041] As an improvement, the first database can also store pipe outlet flow data.

[0042] Preferably, the controller automatically retrieves the inlet valve opening / closing and opening degree data from the first database based on the set outlet temperature of the pipe and the detected temperature of the main pipe.

[0043] As an improvement, the mother tube temperature remains constant. The retrieved data is the closest to the tube-side outlet temperature. Preferably, the set tube-side outlet temperature is T, the outlet temperature in the database is T1, and the retrieved data should be (T-T1). 2The data with the smallest absolute value of the difference. By setting it in this way, the output temperature can be made closest to the set temperature, and then the opening of the inlet valve can be adjusted according to the detected output temperature, so that the output temperature reaches the set temperature as quickly as possible.

[0044] As an improvement, the mother tube temperature varies. The retrieved data is the closest to the tube-side outlet temperature and the mother tube temperature. Preferably, the set outlet temperature is T, the outlet temperature in the database is T1, the detected mother tube temperature is T2, the mother tube temperature in the database is T3, and the retrieved data should be (T-T1). 2 +(T2-T3) 2 Minimum data. By setting it this way, the output temperature can be made closest to the set temperature, and then the opening of the inlet valve can be adjusted according to the detected output temperature, so that the output temperature can reach the set temperature as quickly as possible.

[0045] As an improvement, if the tube side is a heat source, and an increase in the tube side outlet temperature is required, the opening of one or more inlet valves on the left side is increased, while the opening of one or more inlet valves on the right side is decreased, thereby allowing the temperature to rise to the predetermined temperature as quickly as possible. If a decrease in the tube side outlet temperature is required, the opening of one or more inlet valves on the left side is decreased, while the opening of one or more inlet valves on the right side is increased, thereby allowing the temperature to drop to the predetermined temperature as quickly as possible.

[0046] As an improvement, if the tube side is a cold source, and an increase in the tube side outlet temperature is required, the opening of one or more inlet valves on the left side can be reduced, while the opening of one or more inlet valves on the right side can be increased, thereby allowing the temperature to rise to the predetermined temperature as quickly as possible. If a decrease in the tube side outlet temperature is required, the opening of one or more inlet valves on the left side can be increased, while the opening of one or more inlet valves on the right side can be reduced, thereby allowing the temperature to drop to the predetermined temperature as quickly as possible.

[0047] As an improvement, the total opening degree of all inlet valves 11 remains constant, thus ensuring a constant output flow rate. Therefore, this application is able to regulate the temperature to quickly reach the optimal temperature while maintaining a constant flow rate.

[0048] Preferably, one inlet valve 11 is opened to its maximum opening, while all other inlet valves are closed. The temperature of the main pipe and the output temperature of the pipe side are detected, and the temperature data and inlet valve data are stored in the second database, thereby obtaining the output temperature when each inlet valve is opened to its maximum opening.

[0049] Preferably, the controller automatically retrieves data from the second database based on the set outlet temperature T and the detected head pipe temperature. If the output temperature of a particular inlet valve at its maximum opening is equal to the set temperature, then that inlet valve is opened directly to its maximum opening. Otherwise, the controller finds the data of the two adjacent inlet valves (the high-temperature and low-temperature inlet valves) at their maximum openings. Among the data where the output temperature of the high-temperature inlet valve is higher than the set temperature but has the smallest difference, and among the data where the output temperature of the low-temperature inlet valve is lower than the set temperature but has the smallest difference, the controller adjusts the opening of the two inlet valves to adjust the output temperature.

[0050] As an improvement, the main pipe temperature remains constant. The set outlet temperature is T. In the second database, the adjacent high-temperature inlet valve has a higher temperature (Tg), and the low-temperature inlet valve has a lower temperature (Td). The required data to be retrieved is (T-Tg). 2 +(T-Td) 2 Minimum data. By setting it this way, the output temperature can be made closest to the set temperature, and then the opening of the inlet valve can be adjusted according to the detected output temperature, so that the output temperature can reach the set temperature as quickly as possible.

[0051] As an improvement, the main pipe temperature is variable. The set outlet pipe problem is T, the detected main pipe temperature data is T2, the adjacent inlet valve temperature in the database is Tg (higher temperature) and Td (lower temperature), the main pipe temperature is T3, and the required retrieved data is ((Tg+Td) / 2-T). 2 +(T3-T2) 2 Minimum data. By setting it this way, the output temperature can be made closest to the set temperature, and then the opening of the inlet valve can be adjusted according to the detected output temperature, so that the output temperature can reach the set temperature as quickly as possible.

[0052] As an improvement, when the detected output temperature is higher than the predetermined temperature, the opening of the low-temperature inlet valve is increased, and the opening of the high-temperature inlet valve is decreased; when the detected output temperature is lower than the predetermined temperature, the opening of the low-temperature inlet valve is decreased, and the opening of the high-temperature inlet valve is increased. By quickly locating the two inlet valves that need to be opened, and then adjusting the opening and closing of the two adjacent inlet valves, the output temperature is quickly brought to the predetermined temperature.

[0053] As an improvement, if the detected output temperature is higher than the predetermined temperature, and the requirement is still not met even with the low-temperature inlet valve at its maximum opening, then the high-temperature inlet valve is closed, and another inlet valve adjacent to the low-temperature inlet valve (which, when opened alone, has an output temperature lower than the low-temperature inlet valve) is opened. Temperature regulation is achieved by adjusting the openings of both the low-temperature inlet valve and the other inlet valve. Conversely, if the detected output temperature is lower than the predetermined temperature, and the requirement is still not met even with the high-temperature inlet valve at its maximum opening, then the low-temperature inlet valve is closed, and another inlet valve adjacent to the high-temperature inlet valve (which, when opened alone, has an output temperature higher than the high-temperature inlet valve) is opened. Temperature regulation is achieved by adjusting the openings of both the high-temperature inlet valve and the other inlet valve.

[0054] As an improvement, if the tube side is a heat source, and the output temperature at the tube side outlet needs to be increased, the opening of the leftmost inlet valve should be increased first. If the maximum opening still does not meet the requirements, the opening of the inlet valves should be increased sequentially from left to right. If the output temperature of the tube side needs to be reduced, the opening of the rightmost inlet valve should be increased first. If the maximum opening still does not meet the requirements, the opening of the inlet valves should be increased sequentially from right to left.

[0055] If the tube side is a cold source, and an increase in the tube side outlet temperature is required, reduce the opening of the left inlet valve and increase the opening of the right inlet valve to allow the temperature to rise to the predetermined temperature as quickly as possible. If a decrease in the tube side outlet temperature is required, increase the opening of the left inlet valve and decrease the opening of the right inlet valve to allow the temperature to drop to the predetermined temperature as quickly as possible.

[0056] As an improvement, if the tube side is a cold source, and the output temperature at the tube side outlet needs to be reduced, the opening of the leftmost inlet valve should be increased first. If the maximum opening still does not meet the requirements, the inlet valve openings should be increased sequentially from left to right. If the output temperature of the tube side needs to be increased, the opening of the rightmost inlet valve should be increased first. If the maximum opening still does not meet the requirements, the inlet valve openings should be increased sequentially from right to left.

[0057] Preferably, the total opening degree of the high-temperature inlet valve and the low-temperature inlet valve remains constant, thus ensuring a constant output flow rate. Therefore, this application can adjust the temperature to quickly reach the optimal temperature while maintaining a constant flow rate. As an improvement, increasing or decreasing the opening degree of the left inlet valve corresponds to decreasing or increasing the opening degree of at least one inlet valve on the right side of that inlet valve, again ensuring a constant output flow rate.

[0058] This invention also discloses a method for accurately controlling the outlet temperature of the heat exchanger tubes. Maintaining a constant mother tube temperature, the method primarily includes the following steps:

[0059] 1) Open one inlet valve to its maximum opening, close all other inlet valves, detect the output temperature, and store the temperature data and inlet valve data in the second database to obtain the output temperature of the tube when each inlet valve is opened to its maximum opening.

[0060] 2) The user sets the pipe output temperature T. The controller automatically retrieves data from the second database based on the set output temperature T. If the temperature T is equal to the pipe output temperature when a certain inlet valve is opened to its maximum opening, then the controller controls that inlet valve to open and the other inlet valves to close.

[0061] 3) If the database does not find the output temperature of the pipe side when a certain inlet valve is opened to its maximum degree, then find the data Tg and Td of the two adjacent inlet valves, namely the high temperature inlet valve and the low temperature inlet valve, when they are opened to their maximum degree. Tg > T > Td is required. Then, the output temperature is adjusted by adjusting the opening degree of the two inlet valves.

[0062] 4) When the detected output temperature is higher than the predetermined temperature, the opening of the low-temperature inlet valve is increased, and the opening of the high-temperature inlet valve is decreased; when the detected output temperature is lower than the predetermined temperature, the opening of the low-temperature inlet valve is decreased, and the opening of the high-temperature inlet valve is increased. By quickly locating the two inlet valves that need to be opened, and then adjusting the opening and closing of the two adjacent inlet valves, the output temperature is quickly brought to the predetermined temperature.

[0063] As an improvement, when the mother tube temperature is variable, the following steps are included:

[0064] 1) Open one inlet valve to its maximum opening, close all other inlet valves, detect the output temperature of the tube side outlet and the temperature of the mother tube, and store the temperature data and inlet valve data in the second database to obtain the tube side output temperature at the corresponding mother tube temperature when each inlet valve is opened to its maximum opening.

[0065] 2) The user sets the tube-side output temperature T. The controller, based on the set output temperature T and the detected mother tube temperature, automatically retrieves data from the second database. If the temperature T is equal to the tube-side output temperature when a certain inlet valve is opened to its maximum degree, the controller will open that inlet valve and close the other inlet valves.

[0066] 3) If the database cannot find the output temperature of the pipe side when a certain inlet valve is opened to its maximum degree at the corresponding parent pipe temperature, the data for the adjacent inlet valve with the higher temperature is Tg, and the data for the lower temperature is Td. That is, the data for the high-temperature inlet valve and the low-temperature inlet valve at their maximum opening are Tg and Td, respectively. The data for the parent pipe is T3. The required data to be retrieved is ((Tg+Td) / 2-T). 2 +(T3-T2) 2The minimum data is then used. The opening of adjacent inlet valves is adjusted based on the detected output temperature to ensure the output temperature reaches the set temperature as quickly as possible.

[0067] 4) When the detected output temperature is higher than the predetermined temperature, the opening of the low-temperature inlet valve is increased, and the opening of the high-temperature inlet valve is decreased; when the detected output temperature is lower than the predetermined temperature, the opening of the low-temperature inlet valve is decreased, and the opening of the high-temperature inlet valve is increased. By quickly locating the two inlet valves that need to be opened, and then adjusting the opening and closing of the two adjacent inlet valves, the output temperature is quickly brought to the predetermined temperature.

[0068] 5) If the detected output temperature is higher than the predetermined temperature, and the requirement is still not met even with the low-temperature inlet valve at its maximum opening, then the high-temperature inlet valve is closed, and the other inlet valve adjacent to the low-temperature inlet valve (which, when opened alone, has an output temperature lower than the low-temperature inlet valve) is opened. If the detected output temperature is lower than the predetermined temperature, and the requirement is still not met even with the high-temperature inlet valve at its maximum opening, then the low-temperature inlet valve is closed, and the other inlet valve adjacent to the high-temperature inlet valve (which, when opened alone, has an output temperature higher than the high-temperature inlet valve) is opened.

[0069] 6) If the output temperature still does not meet the requirements, continue to repeat step 5) until the required output temperature is finally reached.

[0070] The above method can quickly achieve the desired temperature by controlling only two inlet valves, resulting in higher efficiency.

[0071] As an improvement, the present invention also provides a heat exchanger and method for intelligently controlling the tube-side temperature output based on data memory.

[0072] Temperature sensors are installed at the inlet and outlet of the shell side to detect the temperature at these points. Preferably, the main pipeline temperature, tube-side output temperature, and shell-side inlet and outlet temperatures detected by the first and second temperature monitors are stored in real-time in a third database. Simultaneously, the opening and closing information of each inlet valve is stored in the third database. A one-dimensional deep convolutional neural network is used to extract data features and perform pattern recognition to control the opening and closing of each inlet valve and the degree of opening, thereby controlling the tube-side output temperature.

[0073] The intelligent temperature output control based on data memory includes the following steps:

[0074] 1. Generate dataset: Divide the prepared data into training set / training set labels and detection set / detection set labels.

[0075] 2. Network Training: The training set data is input into the convolutional neural network, and after continuous convolution and pooling, feature vectors are obtained and fed into the fully connected network. By calculating the network output and the training set labels, the network error is obtained. Using the backpropagation algorithm, the network weights, biases, convolution coefficients, and pooling coefficients are continuously adjusted until the error meets the set accuracy requirements, and the network training is completed.

[0076] 3. Network detection: Input the detection set data into the pre-trained network and output the detection result labels.

[0077] 4. Heat exchanger operation: Control the opening and closing of each inlet valve and the degree of opening based on the test result label, thereby controlling the tube-side output temperature.

[0078] This invention provides a novel intelligent heat exchanger for controlling temperature output. Based on machine learning and pattern recognition theories, it designs corresponding heat exchanger inlet valve data by utilizing time-dependent temperature data and inlet valve data from a centralized heat exchanger real-time monitoring system, based on different operating conditions of the shell-side and tube-side parameters of the heat exchanger, and trains a deep convolutional neural network with a large amount of data to control the tube-side output temperature.

[0079] Preferably, the steps for generating the dataset include the following:

[0080] 1) Generating Training Set Data and Labels: Based on different operating conditions of the solar collector, the system reads data values ​​corresponding to each operating condition from the database and generates training set data and operating condition labels for various operating conditions. Preferably, in specific applications, we categorize operating conditions as follows: labels are set according to the inlet valve opening percentage; for example, a label of 100 is assigned when the inlet valve is 100% open, a label of 50 is assigned when the inlet valve is 50% open, and a label of 0 is assigned when the inlet valve is closed. The inlet valve opening label ranges from 0 to 100. The program automatically generates operating condition labels based on different operating conditions.

[0081] 2) Generate detection set data and tags: Based on different operating conditions of the heat exchanger, read the corresponding data values ​​from the database, including temperature and inlet valve data, and generate detection set data and operating condition tags for various operating conditions. The operating condition tags, like those in the training set, are automatically generated by the program based on the operating conditions.

[0082] The specific steps for network training are as follows:

[0083] 1) Read in a set of training data d, the size of which is [M×1×N], where M represents the size of the training batch and 1×N represents one-dimensional training data;

[0084] 2) Perform the first convolution operation on the input training data to obtain the feature map t. Initialize the coefficients of the convolution kernel g, and let the size of g be [P×1×Q], where P represents the number of convolution kernels and [1×Q] represents the size of the convolution kernel. The resulting convolution is t=∑(d*g), and the size of the feature map is [M×1×N×Q].

[0085] 3) Perform max pooling on the feature map t obtained from the convolution operation to obtain the feature map z. Initialize the pooling coefficients, give the pooling stride as p, and the pooling window size as k. The final size of the feature map z is [M×1×(N / p)×Q]. The pooling process reduces the dimensionality of the data.

[0086] 4) Repeat steps 2)-3) above, repeatedly performing convolution and pooling operations to obtain the feature vector x. At this point, the feature extraction process of the convolutional neural network is complete.

[0087] 5) Initialize the weight matrix w and bias b of the fully connected network, feed the extracted feature vector x into the fully connected network, and perform operations with the weight matrix w and bias b to obtain the network output y = ∑(w×x+b);

[0088] 6) Subtract the network output y from the training set label l to obtain the network error e = yl. Take the derivative of the network error and use this derivative to backpropagate, and successively correct the weights w, bias b, pooling coefficients of each layer, and convolution coefficients of each layer of the fully connected network.

[0089] 7) Repeat the above process until the network error e meets the accuracy requirements. The network training process is complete, and a convolutional neural network model is generated.

[0090] The specific steps for network testing are as follows:

[0091] 1) Load the pre-trained convolutional neural network model. At this point, the convolution kernel coefficients, pooling coefficients, network weights w, and bias b of the convolutional neural network have all been trained.

[0092] 2) Input the detection dataset into the pre-trained convolutional neural network and output the detection results. For example, based on the output labels, the operating status can be determined, including the various opening degrees and opening / closing states of the inlet valve.

[0093] This invention proposes a novel method for controlling heat exchanger heat exchange, which makes full use of online monitoring data of the heat exchanger, resulting in fast detection speed and low cost.

[0094] This invention organically integrates data processing technology, machine learning, and pattern recognition theory, which can improve the accuracy of heat exchanger temperature output.

[0095] The specific working process of a convolutional neural network is as follows:

[0096] 1) Input a set of training data d, the size of which is [M×1×N], where M represents the size of the training batch and 1×N represents one-dimensional training data;

[0097] 2) Perform the first convolution operation on the input training data to obtain the feature map t. Initialize the coefficients of the convolution kernel g, and let the size of g be [P×1×Q], where P represents the number of convolution kernels and [1×Q] represents the size of the convolution kernel. The resulting convolution is t=∑(d*g), and the size of the feature map is [M×1×N×Q].

[0098] 3) Perform max pooling on the feature map t obtained from the convolution operation to obtain the feature map z. Initialize the pooling coefficients, set the pooling stride to p, and the pooling window size to k. The final size of the feature map z is [M×1×(N / p)×Q]. The pooling process reduces the dimensionality of the data.

[0099] 4) Repeat steps 2)-3) above, repeatedly performing convolution and pooling operations to obtain the feature vector;

[0100] The heat exchanger operation steps are as follows:

[0101] 1) The opening degree and opening / closing data of each inlet valve are automatically retrieved based on the input temperature and output temperature of the shell side, the input temperature of the tube side, and the set temperature of the tube side.

[0102] 2) When the detected tube output temperature is inconsistent with the set temperature, perform the following operations:

[0103] If the tube side is a heat source, and an increase in the tube side outlet temperature is required, increase the opening of the left inlet valve and decrease the opening of the right inlet valve to quickly raise the temperature to the predetermined temperature. If a decrease in the tube side outlet temperature is required, decrease the opening of the left inlet valve and increase the opening of the right inlet valve to quickly lower the temperature to the predetermined temperature.

[0104] As an improvement, if the tube side is a heat source, and the output temperature at the tube side outlet needs to be increased, the opening of the leftmost inlet valve should be increased first. If the maximum opening still does not meet the requirements, the opening of the inlet valves should be increased sequentially from left to right. If the output temperature of the tube side needs to be reduced, the opening of the rightmost inlet valve should be increased first. If the maximum opening still does not meet the requirements, the opening of the inlet valves should be increased sequentially from right to left.

[0105] If the tube side is a cold source, and an increase in the tube side outlet temperature is required, reduce the opening of the left inlet valve and increase the opening of the right inlet valve to allow the temperature to rise to the predetermined temperature as quickly as possible. If a decrease in the tube side outlet temperature is required, increase the opening of the left inlet valve and decrease the opening of the right inlet valve to allow the temperature to drop to the predetermined temperature as quickly as possible.

[0106] As an improvement, if the tube side is a cold source, and the output temperature at the tube side outlet needs to be reduced, the opening of the leftmost inlet valve should be increased first. If the maximum opening still does not meet the requirements, the inlet valve openings should be increased sequentially from left to right. If the output temperature of the tube side needs to be increased, the opening of the rightmost inlet valve should be increased first. If the maximum opening still does not meet the requirements, the inlet valve openings should be increased sequentially from right to left.

[0107] Repeat step 2) until the output temperature reaches the set value.

[0108] 3) Store the new temperature data and inlet valve data in the third database as data for subsequent data memory operations.

[0109] As an improvement, if the opening of the left inlet valve is increased or decreased, the opening of at least one inlet valve on the right side of that inlet valve will correspondingly decrease or increase, thus keeping the output flow rate constant.

[0110] This invention is based on the theoretical methods of machine memory and pattern recognition. By detecting data, it can automatically retrieve data memory and perform rapid, accurate and intelligent control of the tube-side output temperature of the heat exchanger.

[0111] While the present invention has been disclosed above with reference to preferred embodiments, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for controlling the tube-side temperature of a heat exchanger with a constant main tube temperature, wherein the heat exchanger includes a tube side and a shell side, and heat exchange occurs between the tube-side fluid and the shell-side fluid; the tube side includes a tube-side inlet and a tube-side outlet, the tube side includes heat exchange tubes, the shell side includes a shell, the heat exchange tubes are disposed in the shell, the shell includes multiple sub-shells, the heat exchanger also includes multiple headers, a sub-shell is disposed between two adjacent headers, the headers are provided with tube sheets, and the heat exchange tubes are connected to the tube sheets in adjacent headers; each header is provided with a tube-side inlet or a tube-side outlet, wherein there is one tube-side outlet, which is disposed on the outermost header, and the remaining headers are provided with tube-side inlets; the heat exchanger also includes a main tube, the main tube is connected to the tube-side inlet tube, the tube-side inlet tube is connected to the tube-side inlet, the various tube-side inlet tubes are in parallel, and each tube-side inlet tube is provided with an inlet valve; adjacent sub-shells are interconnected through connecting pipes; With the main tube temperature remaining constant, the control method for controlling the outlet temperature of the heat exchanger tubes mainly includes the following steps: 1) Open one inlet valve to its maximum opening, close all other inlet valves, detect the output temperature, and store the temperature data and inlet valve data in the second database to obtain the output temperature of the tube side when each inlet valve is opened to its maximum opening. 2) The user sets the tube output temperature T. The controller automatically retrieves data from the second database based on the set output temperature T. If the temperature T is equal to the tube output temperature when a certain inlet valve is opened to its maximum opening, then the controller controls that inlet valve to open and the other inlet valves to close. 3) If the database does not find the output temperature of the pipe side when a certain inlet valve is opened to its maximum degree, then find the data Tg and Td of the two adjacent inlet valves, namely the high temperature inlet valve and the low temperature inlet valve, when they are opened to their maximum degree. Tg > T > Td is required. Then, the output temperature is adjusted by adjusting the opening degree of the two inlet valves.

2. The control method as described in claim 1, characterized in that, When the detected output temperature is higher than the predetermined temperature, the opening of the low-temperature inlet valve is increased, and the opening of the high-temperature inlet valve is decreased.

3. The control method as described in claim 1, characterized in that, When the detected output temperature is lower than the predetermined temperature, the opening of the low-temperature inlet valve is reduced, and the opening of the high-temperature inlet valve is increased.

4. The control method as described in claim 1, characterized in that, It also includes a controller, which is connected to the inlet valve via data connection. The pipe outlet is also equipped with a pipe outlet temperature sensor. The controller controls the opening and closing of each inlet valve and the degree of opening based on the temperature detected by the pipe outlet temperature sensor.

5. The control method as described in claim 1, characterized in that, Open one inlet valve to its maximum opening while closing all other inlet valves. Detect the main pipe temperature and the pipe-side output temperature. Store the temperature data and inlet valve data in a second database to obtain the output temperature when each inlet valve is opened to its maximum opening.

6. The control method as described in claim 5, characterized in that, The controller automatically retrieves data from the second database based on the set outlet temperature T and the detected main pipe temperature. If the output temperature of a certain inlet valve when it is opened to its maximum opening is equal to the set temperature, then the controller directly opens that inlet valve to its maximum opening. Otherwise, it finds the data of the two adjacent inlet valves, namely the high-temperature inlet valve and the low-temperature inlet valve, when they are opened to their maximum opening. Among the data where the output temperature of the high-temperature inlet valve is higher than the set temperature but the difference is the smallest, and among the data where the output temperature of the low-temperature inlet valve is lower than the set temperature but the difference is the smallest, then the controller adjusts the output temperature by adjusting the opening of the two inlet valves.

Images