Modeling method of heat exchanger with liquid level control in shell side, heat exchanger and electronic equipment

Abstract

The present invention discloses a modeling method for a heat exchanger with liquid level control in the shell side, comprising: obtaining a first shell side fluid temperature value of the heat exchanger to be modeled; calculating the temperature difference between both ends of the heat exchanger to be modeled, the average heat transfer temperature difference and the heat transfer rate; calculating the tube side fluid molar flow value and the preset first shell side fluid enthalpy value of the heat exchanger to be modeled, and determining the second shell side fluid enthalpy value after heat exchange based on the heat transfer rate, the tube side fluid molar flow value and the first shell side fluid enthalpy value; calling PH flash evaporation based on the second shell side fluid enthalpy value to calculate the second shell side fluid temperature value after shell side heat exchange of the heat exchanger to be modeled; calculating the temperature difference before and after the shell side heat exchange of the heat exchanger to be modeled; when the temperature difference before and after the shell side heat exchange is lower than a preset threshold value, calculating the tube side fluid outlet enthalpy value of the heat exchanger to be modeled after heat exchange; calling PH flash evaporation based on the tube side fluid outlet enthalpy value to calculate the tube side fluid outlet temperature value of the heat exchanger to be modeled after heat exchange.

Description

Technical Field

[0001] The present application relates to the field of heat exchangers, and in particular to a modeling method for a shell-side heat exchanger with liquid level control, a heat exchanger, and electronic equipment. Background Art

[0002] Chemical process simulation is to reproduce the actual production process on the computer by establishing a mathematical model, and obtain detailed material balance and energy balance data for the entire process or unit process. It mainly includes important parameters such as raw material consumption, utility consumption, product composition and quality. Chemical process simulation is divided into steady-state simulation and dynamic simulation. Dynamic simulation refers to the change of all parameters over time during the simulation process, which is mainly used for the analysis of process dynamic characteristics, the formulation of control plans, the optimization of start-up and shutdown plans, and the development of operator training software. Chemical simulation software, whether dynamic or steady-state, contains basic unit module libraries, which are unit mathematical models of actual equipment in the process.

[0003] The shell-side heat exchanger with liquid level control is a device unit often encountered in process simulation. The fluid in the tube side exchanges heat with the liquid and gas in the shell side. This heat exchange equipment is often used as a waste heat boiler, steam generator, etc. in factories.

[0004] The existing commercial dynamic simulation systems available on the market do not have a high-precision unit mechanism model specifically for shell-side heat exchangers with liquid level control. Currently, the simulation of shell-side heat exchangers with liquid level control is composed of several unit modules. On the one hand, this modeling is cumbersome, and on the other hand, there are some shortcomings. It cannot truly reflect all the dynamic characteristics of shell-side heat exchangers with liquid level control, and there are problems such as calculation delay or low accuracy. Summary of the invention

[0005] The technical problem to be solved by the embodiments of the present application is to provide a modeling method, a heat exchanger and an electronic device for a shell-side heat exchanger with liquid level control, so as to solve the technical problems that the simulation of the existing heat exchanger is composed of several unit modules, the modeling is cumbersome, and all the dynamic characteristics of the shell-side heat exchanger with liquid level control cannot be truly reflected, and there are calculation delays and low precision.

[0006] To achieve the above objectives, the present application embodiment adopts the following technical solutions:

[0007] In a first aspect, an embodiment of the present application provides a modeling method for a shell-side heat exchanger with liquid level control, the method comprising:

[0008] Obtain the first shell side fluid temperature value of the heat exchanger to be modeled;

[0009] Calculate the temperature difference between the two ends of the heat exchanger to be modeled, the average temperature difference of heat transfer, and the heat transfer rate;

[0010] Calculating the tube-side fluid molar flow value and the preset first shell-side fluid enthalpy value of the heat exchanger to be modeled, and determining the second shell-side fluid enthalpy value after heat exchange based on the heat transfer rate, the tube-side fluid molar flow value and the first shell-side fluid enthalpy value;

[0011] Based on the enthalpy value of the second shell-side fluid, pH flash is called to calculate the temperature value of the second shell-side fluid after the shell-side heat exchange of the heat exchanger to be modeled;

[0012] Calculating the temperature difference before and after the shell-side heat exchange of the heat exchanger to be modeled, wherein the temperature difference before and after the shell-side heat exchange is determined by the first shell-side fluid temperature value and the second shell-side fluid temperature value;

[0013] When the temperature difference before and after the shell-side heat exchange is lower than a preset threshold, the outlet enthalpy of the tube-side fluid after the heat exchange of the heat exchanger to be modeled is calculated;

[0014] Based on the outlet enthalpy value of the tube-side fluid, PH flash is called to calculate the outlet temperature value of the tube-side fluid after heat exchange of the heat exchanger to be modeled.

[0015] In the second aspect, an embodiment of the present application provides a shell-side heat exchanger with liquid level control, wherein the heat exchanger includes a shell side and a tube side, and the second shell-side fluid temperature value and the tube-side fluid outlet temperature value of the heat exchanger after heat exchange are calculated based on the modeling method of the shell-side heat exchanger with liquid level control described in the first aspect.

[0016] In a third aspect, an embodiment of the present application provides an electronic device, comprising a processor and a memory, wherein the memory stores at least one instruction, at least one program, a code set or an instruction set, and the at least one instruction, the at least one program, the code set or the instruction set are executed by the processor to implement the modeling method of a shell-side heat exchanger with liquid level control as described in the first aspect above.

[0017] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores at least one instruction, at least one program, a code set or an instruction set, and the at least one instruction, the at least one program, the code set or the instruction set are executed by a processor to implement the modeling method of a shell-side heat exchanger with liquid level control as described in the first aspect above.

[0018] The beneficial effects of the embodiments of the present application are as follows: the embodiments of the present application provide a modeling method, a heat exchanger and an electronic device for a shell-side heat exchanger with liquid level control. On the one hand, the shell side strictly simulates the existence of gas-liquid two phases, and the two phases are in a phase equilibrium state; for the tube side, it is assumed that there is no material storage and no phase change occurs. Reasonable assumptions make the modeling method closer to reality; on the other hand, the establishment of this modeling method can make the simulation operation of the shell-side heat exchanger with liquid level control very simple in the future, with high calculation accuracy and fast speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic flow chart of a modeling method for a shell-side heat exchanger with liquid level control provided in one embodiment of the present application;

[0020] Figure 2 A schematic diagram of the structure of a shell-side heat exchanger with liquid level control provided in one embodiment of the present application;

[0021] Figure 3 A schematic diagram of the structure of an electronic device provided in accordance with an embodiment of the present application. DETAILED DESCRIPTION

[0022] The technical solution of the present application is further described in detail below through specific embodiments and in combination with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0023] The present application provides a modeling method, a heat exchanger and an electronic device for a shell-side heat exchanger with liquid level control, so as to solve the technical problems that the simulation of the existing heat exchanger is composed of several unit modules, the modeling is complicated, and all the dynamic characteristics of the shell-side heat exchanger with liquid level control cannot be truly reflected, and there are calculation delays and low precision.

[0024] Before a specific description is given, some terms proposed in the embodiments of the present application are explained.

[0025] The technical solutions provided by each embodiment of the present application are described in detail below in conjunction with the accompanying drawings.

[0026] Please see attached Figure 1 , which shows a flow chart of a modeling method of a shell-side heat exchanger with liquid level control provided by an embodiment of the present application, the method comprising:

[0027] S101, obtaining the first shell fluid temperature value t of the heat exchanger to be modeled shell0 ;

[0028] For step S101, when the heat exchanger to be modeled is in the first round of heat exchange, the first shell-side fluid temperature value t shell0 is a preset constant; when the heat exchanger to be modeled is not the first round of heat exchange, the second shell-side fluid temperature value t after the shell-side heat exchange of the heat exchanger to be modeled is shell1 As the first shell side fluid temperature value t shell0 .

[0029] Specifically, when performing the first round of calculations on the heat exchanger to be modeled, the first shell side fluid temperature value t shell0 Set the temperature to 25℃. In the calculations after the first round, the second shell fluid temperature value t of the previous round is used. shell1 As the first shell fluid temperature value t of the next round shell0 .

[0030] S102, calculating the temperature differences Δt1 and Δt2 at both ends of the heat exchanger to be modeled, the average heat transfer temperature difference Δt, and the heat transfer rate Q;

[0031] With respect to step S102, in one embodiment, calculating the temperature differences Δt1 and Δt2 at both ends of the heat exchanger to be modeled includes:

[0032] Obtain the preset tube fluid inlet temperature value t of the heat exchanger to be modeled tube_in , preset the outlet temperature of the fluid in the tube tube_out , based on the preset tube fluid inlet temperature value t of the heat exchanger to be modeled tube_in , preset the outlet temperature of the fluid in the tube tube_out , the first shell side fluid temperature value t shell0 Determine the temperature difference Δt1 and Δt2 at both ends of the heat exchanger to be modeled. The specific calculation formula is as follows:

[0033]

[0034] In one embodiment, the average heat transfer temperature difference Δt is calculated based on the temperature differences Δt1 and Δt2 at both ends of the heat exchanger to be modeled. The specific calculation formula is as follows:

[0035]

[0036] In one embodiment, the preset heat transfer coefficient value K, the preset heat transfer area value A, and the preset correction factor value Ft of the heat exchanger to be modeled are obtained, and the heat transfer rate Q is calculated based on the preset heat transfer coefficient value K, the preset heat transfer area value A, the preset correction factor value Ft and the average heat transfer temperature difference of the heat exchanger to be modeled. The specific calculation formula is as follows:

[0037] Q=KAΔtF t

[0038] S103, calculating the molar flow value F of the tube-side fluid of the heat exchanger to be modeled molar_tube , the preset first shell fluid enthalpy value H shell0 , based on the heat transfer rate Q, the tube side fluid molar flow value F molar_tube , the first shell side fluid enthalpy H shell0 Determine the enthalpy value H of the second shell fluid after heat exchange shell1 ;

[0039] For step S103, in one embodiment, the molar flow rate value F of the tube-side fluid of the heat exchanger to be modeled is calculated. molar_tube include:

[0040] Obtain the preset flow coefficient Cv and the preset tube inlet pressure P of the heat exchanger to be modeled tube_in , preset pipe outlet pressure P tube_out , preset pipe fluid molecular weight MW tube And the preset tube fluid molar density ρ molar_tube ;

[0041] Based on the preset flow coefficient Cv, the preset pipe inlet pressure P tube_in , preset pipe outlet pressure P tube_out , preset pipe fluid molecular weight MW tube And the preset tube fluid molar density ρ molar_tube Calculate the molar flow rate value F of the tube side fluid of the heat exchanger to be modeled molar_tube The specific calculation formula is as follows:

[0042]

[0043] In one embodiment, the second shell side fluid enthalpy H is calculated. shell1 The specific formula is as follows:

[0044] Q=F molar_shell *(H shell0 -H shell1 )

[0045] S104, based on the second shell-side fluid enthalpy H shell1 Call PH flash to calculate the second shell side fluid temperature value t after shell side heat exchange of the heat exchanger to be modeled shell1 ;

[0046] For step S104, the second shell side fluid temperature value t shell1 The specific calculation formula is as follows:

[0047] t shell1 =PH(H shell1 )

[0048] S105, calculating the temperature difference before and after the shell-side heat exchange of the heat exchanger to be modeled, wherein the temperature difference before and after the shell-side heat exchange is calculated by the first shell-side fluid temperature value t shell0 , the second shell side fluid temperature value t shell1 Sure;

[0049] For step S105, the specific formula for calculating the temperature difference before and after the shell-side heat exchange of the heat exchanger to be modeled is as follows:

[0050] abs(t shell1 -t shell0 )

[0051] S106, when the temperature difference before and after the shell-side heat exchange is lower than the preset threshold ε, calculate the outlet enthalpy value H of the tube-side fluid after heat exchange of the heat exchanger to be modeled tube_out ;

[0052] With respect to step 106, in one embodiment, the formula for determining whether the temperature difference before and after the shell-side heat exchange is lower than a preset threshold value ε is as follows:

[0053] abs(t shell1 -t shell0 )<ε

[0054] It can be understood that ε represents the temperature difference accuracy, which can be obtained by artificial preset.

[0055] In one embodiment, the outlet enthalpy value H of the tube-side fluid after heat exchange of the heat exchanger to be modeled is calculated. tube_out include:

[0056] Obtain the preset tube fluid inlet enthalpy value H of the heat exchanger to be modeled tube_in , based on the heat transfer rate Q of the heat exchanger to be modeled, the molar flow value F of the tube fluid molar_tube , preset tube fluid inlet enthalpy value H tube_in Calculate the outlet enthalpy H of the tube fluid after heat exchange tube_out The specific calculation formula is as follows:

[0057] Q=F molar_tube *(H tube_in -H tube_out )

[0058] S107, based on the outlet enthalpy value H of the tube-side fluid tube_out Call PH flash to calculate the outlet temperature value t of the tube fluid after heat exchange in the heat exchanger to be modeled tube_out .

[0059] In one embodiment, the tube-side fluid outlet temperature value t is calculated. tube_out The specific calculation formula is as follows:

[0060] ttube_out =PH(H tube_out )

[0061] In one embodiment, when the temperature difference before and after the shell-side heat exchange is not lower than a preset threshold, the step of taking the second shell-side fluid temperature value after the shell-side heat exchange of the heat exchanger to be modeled as the first shell-side fluid temperature value is cyclically performed, and the temperature difference before and after the shell-side heat exchange is iteratively calculated until it is lower than the preset threshold.

[0062] Compared with the ordinary heat exchanger modeling calculation, the technical solution adopted in the above embodiment has only one layer of iteration, that is, iterative calculation is performed when calculating the temperature difference before and after the shell heat exchange. Therefore, the technical solution of the above embodiment has the technical effect of fast calculation speed, and can meet the real-time calculation requirements in large-scale process simulation. This calculation process is based on the assumption that no phase change occurs in the tube side of the heat exchanger (because there is no space in the tube side, and there is no time for the fluid to undergo a phase change). Based on this assumption, the mass transfer from the gas phase to the liquid phase in the tube side and the mass transfer from the liquid phase to the gas phase in the tube side can be ignored in the calculation process of the tube side (because there is no time to complete), and it is considered that the liquid in the tube side is in a superheated state or the gas is in a supercooled state.

[0063] With regard to the contents recorded in the embodiments of the present application, after the heat exchange calculation is completed, when the pH flash is called in the above calculation of the second shell-side fluid temperature value, the density of the shell-side vapor-liquid phase fluid, the vaporization fraction, and the molecular weight of the shell-side vapor-liquid phase fluid can also be obtained at the same time. The molar amount of the shell-side liquid can be calculated by the vaporization fraction, and the liquid hydrocarbon level height can be further calculated. One calculation method is as follows:

[0064]

[0065]

[0066] The gas phase space pressure in the shell is calculated by the above equation and liquid outlet pressure

[0067] In the formula, F in is the molar flow rate of the feed stream, F vapor is the molar flow rate of gas phase discharge, F liquid is the molar flow rate of liquid phase discharge, and the above parameters are provided by the simulation system (or user).

[0068] ρ is the mass density of the material in the tower, in kg / m 3 Z is the compression factor of the gas in the heat exchanger, R is the gas constant, and T is the temperature in the tower. v is the number of moles of gas in the tower, in kmo, ρ mass_shell is the shell side liquid mass density, kg / m3 The flow rate parameter is obtained by calling the pH flash calculation when calculating the shell temperature.

[0069] g is the acceleration due to gravity, m / s 2 is a constant.

[0070] Please see attached Figure 2 , which shows a schematic structural diagram of a shell-side heat exchanger with liquid level control provided by an embodiment of the present application, wherein the heat exchanger includes a shell side and a tube side, and the second shell-side fluid temperature value and the tube-side fluid outlet temperature value of the heat exchanger after heat exchange are calculated based on the modeling method of the shell-side heat exchanger with liquid level control described in any of the embodiments.

[0071] Please see attached Figure 3 , which shows a schematic diagram of the structure of an electronic device provided by an embodiment of the present application, which may include: at least one network interface 302, a memory 303 and at least one processor 301. The various components in the electronic device are coupled together through a bus system 304. It can be understood that the bus system 304 is used to realize the connection and communication between these components. In addition to the data bus, the bus system 304 also includes a power bus, a control bus and a status signal bus, but for the sake of clarity, they are not shown in the attached figure. Figure 3 Various buses are labeled as bus system 304 .

[0072] In some implementations, the memory 303 stores the following elements, executable modules or data structures, or a subset thereof, or an extended set thereof: an operating system 3031 and an application program 3032 .

[0073] The operating system 3031 includes various system programs, such as a framework layer, a core library layer, a driver layer, etc., which are used to implement various mailing services and process hardware-based tasks. The application 3032 includes various application programs, such as a media player (Media Player), a browser (Browser), etc., which are used to implement various application services. The program for implementing the method of the embodiment of the present application can be included in the application.

[0074] In the above embodiment, the electronic device also includes: at least one instruction, at least one program, code set or instruction set stored in the memory 303, and the at least one instruction, the at least one program, the code set or instruction set can be executed by the processor 301 to implement the steps of the modeling method of the shell-side heat exchanger with liquid level control in any of the embodiments of the present application.

[0075] In one embodiment, the present application also provides a computer-readable storage medium, which stores at least one instruction, at least one program, a code set or an instruction set. When the at least one instruction, the at least one program, the code set or the instruction set is executed by a processor, the steps of the modeling method of a shell-side heat exchanger with liquid level control described in any of the embodiments of the present application are implemented.

[0076] Those of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment method can be implemented by instructing the relevant hardware through a computer program, and the at least one instruction, at least one program, code set or instruction set can be stored in a non-volatile computer-readable storage medium. When the at least one instruction, at least one program, code set or instruction set is executed, it can implement the steps of any map drawing method described in the embodiment of the present application. Among them, any reference to memory, storage, database or other media used in the embodiments provided in the present application may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0077] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods, which are merely illustrative and not restrictive. At the same time, for those skilled in the art, according to the ideas of the present application, there may be changes in the specific implementation methods and application scopes, which all fall within the scope of protection of the present application.

Claims

1. A modeling method for a shell-side heat exchanger with liquid level control, characterized in that: The method comprises: Obtain the first shell side fluid temperature value of the heat exchanger to be modeled; Calculate the temperature difference between the two ends of the heat exchanger to be modeled, the average temperature difference of heat transfer, and the heat transfer rate; Calculating the tube-side fluid molar flow value of the heat exchanger to be modeled, obtaining a preset first shell-side fluid enthalpy value, and determining the second shell-side fluid enthalpy value after heat exchange based on the heat transfer rate, the tube-side fluid molar flow value, and the first shell-side fluid enthalpy value; Based on the enthalpy value of the second shell-side fluid, pH flash is called to calculate the temperature value of the second shell-side fluid after the shell-side heat exchange of the heat exchanger to be modeled; Calculating the temperature difference before and after the shell-side heat exchange of the heat exchanger to be modeled, wherein the temperature difference before and after the shell-side heat exchange is determined by the first shell-side fluid temperature value and the second shell-side fluid temperature value; When the temperature difference before and after the shell-side heat exchange is lower than a preset threshold, the outlet enthalpy of the tube-side fluid after the heat exchange of the heat exchanger to be modeled is calculated; Based on the outlet enthalpy value of the tube-side fluid, pH flash is called to calculate the outlet temperature value of the tube-side fluid of the heat exchanger to be modeled after heat exchange; When the heat exchanger to be modeled is in the first round of heat exchange, the first shell-side fluid temperature value is a preset constant; When the heat exchanger to be modeled is not in the first round of heat exchange, the second shell-side fluid temperature value after shell-side heat exchange of the heat exchanger to be modeled is used as the first shell-side fluid temperature value.

2. The modeling method of a shell-side heat exchanger with liquid level control according to claim 1 is characterized in that: When the temperature difference before and after the shell-side heat exchange is not lower than the preset threshold, the step of cyclically taking the second shell-side fluid temperature value after the shell-side heat exchange of the heat exchanger to be modeled as the first shell-side fluid temperature value is performed, and the temperature difference before and after the shell-side heat exchange is iteratively calculated until it is lower than the preset threshold.

3. The modeling method of a shell-side heat exchanger with liquid level control according to claim 1 is characterized in that: Calculating the temperature difference between the two ends of the heat exchanger to be modeled includes: Obtain a preset tube-side fluid inlet temperature value and a preset tube-side fluid outlet temperature value of the heat exchanger to be modeled, and determine the temperature difference between the two ends of the heat exchanger to be modeled based on the preset tube-side fluid inlet temperature value, the preset tube-side fluid outlet temperature value, and the first shell-side fluid temperature value of the heat exchanger to be modeled.

4. The modeling method of a shell-side heat exchanger with liquid level control according to claim 3 is characterized in that: The heat transfer average temperature difference is calculated based on the temperature difference between the two ends of the heat exchanger to be modeled.

5. The modeling method of a shell-side heat exchanger with liquid level control according to claim 4 is characterized in that: Obtain a preset heat transfer coefficient value, a preset heat transfer area value, and a preset correction factor value of the heat exchanger to be modeled, and calculate the heat transfer rate based on the preset heat transfer coefficient value, the preset heat transfer area value, the preset correction factor value, and the average heat transfer temperature difference of the heat exchanger to be modeled.

6. The modeling method of a shell-side heat exchanger with liquid level control according to claim 1 is characterized in that: Calculating the molar flow rate of the tube-side fluid of the heat exchanger to be modeled includes: Obtaining a preset flow coefficient, a preset tube-side inlet pressure, a preset tube-side outlet pressure, a preset tube-side fluid molecular weight, and a preset tube-side fluid molar density of the heat exchanger to be modeled; The molar flow value of the tube-side fluid of the heat exchanger to be modeled is calculated based on the preset flow coefficient, the preset tube-side inlet pressure, the preset tube-side outlet pressure, the preset tube-side fluid molecular weight and the preset tube-side fluid molar density.

7. The modeling method of a shell-side heat exchanger with liquid level control according to claim 6 is characterized in that: Calculating the outlet enthalpy of the tube-side fluid after heat exchange in the heat exchanger to be modeled includes: The preset tube-side fluid inlet enthalpy value of the heat exchanger to be modeled is obtained, and the tube-side fluid outlet enthalpy value after heat exchange is calculated based on the heat transfer rate of the heat exchanger to be modeled, the tube-side fluid molar flow value, and the preset tube-side fluid inlet enthalpy value.

8. A heat exchanger with liquid level control in the shell side, characterized in that: The heat exchanger includes a shell side and a tube side. The second shell side fluid temperature value and the tube side fluid outlet temperature value after heat exchange are calculated based on the modeling method of the shell side heat exchanger with liquid level control according to any one of claims 1-7.

9. An electronic device, characterized in that: The electronic device includes a processor and a memory, wherein the memory stores at least one instruction, at least one program, a code set or an instruction set, and the at least one instruction, the at least one program, the code set or the instruction set are executed by the processor to implement the modeling method of a shell-side heat exchanger with liquid level control as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores at least one instruction, at least one program, a code set or an instruction set, and the at least one instruction, the at least one program, the code set or the instruction set are executed by a processor to implement the modeling method of a shell-side heat exchanger with liquid level control as described in any one of claims 1 to 7.

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