A thermal bypass temperature control system

Abstract

The application discloses a heat bypass temperature control system, wherein a temperature controller outputs a temperature control value according to the outlet temperature of the heat medium in the oil supply main pipeline and a preset target outlet temperature, the input end of a steam valve position controller is connected with the output end of the temperature controller, after the temperature control value is obtained, the opening of the steam regulating valve is determined according to the temperature control value and a preset valve position value, and the steam regulating valve is controlled, so that the steam flow of the heat exchanger is adjusted. The application controls the flow of steam, can gradually reduce the steam load of the heat bypass system when the temperature of the heat medium needs to be reduced, solves the problem that when the temperature of the heat medium is reduced in the prior art, a large amount of heat medium flows through the bypass pipeline, but a large amount of steam is still introduced into the heat exchanger for heating, thereby reducing energy consumption, saving production cost, and protecting the mechanical integrity of the heat exchanger, and the heat exchanger is not damaged by dry burning; when the temperature of the heat medium needs to be adjusted, the response speed of the system can be accelerated by simultaneously adjusting the heat medium flow and the steam flow of the main bypass.

Description

Technical Field

[0001] This application relates to the field of heat exchange system technology, and in particular to a heat bypass temperature control system. Background Technology

[0002] In the thermal bypass system of the carbomer unit, steam heat exchange is used to heat the thermal bypass system. According to the process requirements, the operating temperature of the thermal bypass system needs to be changed within one production cycle using the rake dryer of the thermal unit, and the cooling process needs to be rapid in order to meet the product quality requirements.

[0003] Currently, to meet process requirements, the heat bypass system of the carbomer unit adopts a heat bypass control scheme using a three-way regulating valve controlled by the heat exchanger outlet temperature. For example... Figure 1 As shown, the device includes an outlet temperature controller 001 and a three-way regulating valve 002. The input of the outlet temperature controller 001 is connected to the outlet of the heat exchanger 003 at the bypass pipe 004 manifold, used to monitor and control the outlet temperature; the output is connected to the three-way regulating valve 002, used to control the flow rate of hot oil through the heat exchanger 003 and the bypass pipe 004. If the heating device 005 needs to adjust the hot oil temperature, the outlet temperature controller 001 controls the three-way regulating valve 002 to adjust the flow ratio through the heat exchanger 003 and the bypass pipe 004, thereby adjusting the outlet temperature.

[0004] The heat bypass system's heat-using device 005 rake dryer needs to switch from a high-temperature operation stage to a low-temperature operation stage in the set program, and the low-temperature operation stage lasts for a long time. Since the steam flow is not controlled, a large amount of hot oil flows through the bypass pipe 004 during this period, but a large amount of steam is still introduced into the heat exchanger 003 for heating, which results in energy waste, increased operating costs, and may also cause problems such as dry burning of the heat exchanger 003 and damage to its mechanical integrity. Summary of the Invention

[0005] The purpose of this application is to overcome the limitation of existing thermal bypass temperature control systems in controlling the flow rate of steam when controlling the flow rate of the main bypass heat medium, and to provide a thermal bypass temperature control system.

[0006] The technical solution of this application provides a thermal bypass temperature control system, the system including a main pipeline, a heat exchanger, a bypass pipeline, a main oil supply pipeline, a main oil return pipeline, and a heat-using device; The heat exchanger is connected in the main pipeline. One end of the main pipeline is connected to the oil inlet of the heat-using device through the main oil supply pipeline, and the other end is connected to the oil outlet of the heat-using device through the main oil return pipeline. The bypass pipeline is connected in parallel to both ends of the main pipeline. It also includes steam regulating valves, temperature controllers, and steam valve position controllers; The steam regulating valve is used to regulate the steam flow rate of the heat exchanger; The temperature controller obtains the outlet temperature of the heat medium and the target outlet temperature in the main oil supply pipeline at its input terminal, and outputs the temperature control value after determining the temperature control value based on the heat medium outlet temperature and the target outlet temperature. The input terminal of the steam valve position controller is connected to the output terminal of the temperature controller to obtain the temperature control value, and after determining the opening degree of the steam regulating valve based on the temperature control value and the preset valve position value, output the value from the output terminal. The output terminal of the steam valve position controller is connected to the steam regulating valve.

[0007] Furthermore, the temperature controller is specifically used for: The heat medium outlet temperature is compared with the target outlet temperature, and the temperature control value is output based on the temperature difference between the heat medium outlet temperature and the target outlet temperature. The steam valve position controller is specifically used for: The temperature control value is compared with the preset valve position value, and the opening of the steam regulating valve is adjusted according to the relationship between the temperature control value and the preset valve position value.

[0008] Furthermore, adjusting the opening of the steam regulating valve based on the relationship between the temperature control value and the preset valve position value specifically includes: If the temperature control value is equal to the preset valve position value, then the opening of the steam regulating valve will not be adjusted. If the temperature control value is greater than the preset valve position value, the opening of the steam regulating valve will be continuously reduced at a preset rate. If the temperature control value is less than the preset valve position value, the opening of the steam regulating valve will be continuously increased at a preset rate.

[0009] Furthermore, it also includes heat medium regulating valve assembly, flow controller, and heat medium controller; The heat medium regulating valve group is used to regulate the heat medium flow rate of the main pipeline and the bypass pipeline; The input terminal of the flow controller acquires the total flow rate of the heat medium in the return oil main pipeline, and outputs the flow rate value from the output terminal after determining the total flow rate of the heat medium. The input terminal of the heat medium controller is connected to the output terminal of the temperature controller and the output terminal of the flow controller. It is used to obtain the temperature control value and the flow rate value, and to determine the opening degree of the heat medium regulating valve group based on the temperature control value and the flow rate value before outputting it from the output terminal. The output terminal of the heat medium controller is connected to the heat medium regulating valve group.

[0010] Furthermore, the heat medium regulating valve group includes a bypass regulating valve and a main regulating valve. The bypass regulating valve is connected in the bypass pipeline and is used to control the flow rate of the heat medium flowing through the bypass pipeline. The main regulating valve is in the main pipeline and is used to control the flow rate of the heat medium flowing through the heat exchanger. The heat medium controller is specifically used for: The opening degree of the bypass regulating valve is determined based on the temperature control value and the flow rate value; The opening degree of the main control valve is determined based on the flow rate value and the opening degree of the bypass control valve.

[0011] Furthermore, the heat medium controller includes a bypass controller; The input terminal of the bypass controller is connected to the output terminal of the temperature controller and the output terminal of the flow controller. It is used to obtain the temperature control value and the flow rate value, and to determine the opening degree of the bypass regulating valve based on the temperature control value and the flow rate value before outputting it from the output terminal. The output terminal of the bypass controller is connected to the bypass regulating valve.

[0012] Furthermore, the bypass controller calculates the opening degree of the bypass regulating valve according to the following formula: (1) Where c is the opening degree of the bypass regulating valve, k is the flow coefficient of the main regulating valve and the bypass regulating valve under the design operating conditions, a is the flow value, and b is the temperature control value; Calculate the value of k using the following formula: (2) Wherein, CV1 is the flow coefficient of the bypass control valve, CV2 is the flow coefficient of the main control valve, ΔP1 is the pressure drop of the bypass control valve, and ΔP2 is the pressure drop of the main control valve.

[0013] Furthermore, the heat medium controller also includes a main circuit controller; The input terminal of the main circuit controller is connected to the output terminal of the flow controller and the output terminal of the bypass controller. It is used to obtain the flow rate value and the opening degree of the bypass regulating valve, and to determine the opening degree of the main circuit regulating valve based on the flow rate value and the opening degree of the bypass regulating valve before outputting it from the output terminal. The output terminal of the main circuit controller is connected to the main circuit regulating valve.

[0014] Furthermore, the main circuit controller calculates the opening degree of the main circuit regulating valve according to the following formula: (3) Wherein, d is the opening degree of the main regulating valve, a is the flow rate value, c is the opening degree of the bypass regulating valve, and k is the flow coefficient of the main regulating valve and the bypass regulating valve under the design operating conditions.

[0015] Furthermore, it also includes a user input device, the output of which is connected to the input of the temperature controller and the input of the steam valve position controller, for inputting the target outlet temperature and / or the preset valve position value.

[0016] The above technical solution has the following beneficial effects: The temperature controller in this application outputs a temperature control value based on the outlet temperature of the heat medium in the main oil supply pipeline and a preset target outlet temperature. The input terminal of the steam valve position controller is connected to the output terminal of the temperature controller. After obtaining the temperature control value, the opening degree of the steam regulating valve is determined based on the temperature control value and the preset valve position value, and the steam regulating valve is controlled to regulate the steam flow of the heat exchanger. This application controls the steam flow, which can gradually reduce the steam load of the heat bypass system when the heat medium temperature needs to be reduced. This solves the problem in the prior art where a large amount of heat medium flows through the bypass pipeline but a large amount of steam is still introduced into the heat exchanger for heating when the heat medium temperature is reduced, thereby reducing energy consumption, saving production costs, and protecting the mechanical integrity of the heat exchanger from dry burning damage. When the heat medium temperature needs to be adjusted, the system response speed can be accelerated by simultaneously adjusting the heat medium flow and steam flow of the main bypass. Attached Figure Description

[0017] The disclosure of this application will become more readily understood with reference to the accompanying drawings. It should be understood that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this application. In the drawings: Figure 1 This is a schematic diagram of the structure of a thermal bypass temperature control system in the prior art; Figure 2 This is a schematic diagram of the structure of a thermal bypass temperature control system in one embodiment of this application.

[0018] Appendix Label Reference Table: Outlet temperature controller 001, three-way regulating valve 002, heat exchanger 003, bypass pipeline 004, heat-using device 005, main pipeline 01, heat exchanger 02, bypass pipeline 03, main oil supply pipeline 04, main oil return pipeline 05, heat-using device 06, temperature controller 07, steam regulating valve 08, steam valve position controller 09, flow controller 10, bypass controller 11, bypass regulating valve 12, main pipeline controller 13, main pipeline regulating valve 14. Detailed Implementation

[0019] The specific embodiments of this application will be further described below with reference to the accompanying drawings.

[0020] It is readily understood that, based on the technical solution of this application, various structural and implementation methods can be interchanged by those skilled in the art without altering the essential spirit of this application. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this application and should not be considered as the entirety of this application or as limitations or restrictions on the technical solution of the application.

[0021] The directional terms such as up, down, left, right, front, back, front, back, top, and bottom mentioned or possibly used in this specification are defined relative to the structures shown in the accompanying drawings. These are relative concepts and may therefore vary depending on their location and usage. Therefore, these or other directional terms should not be interpreted as restrictive. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0022] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meanings of the above in this application according to the specific circumstances.

[0023] like Figure 2 As shown in the example of this application, a thermal bypass temperature control system includes a main pipeline 01, a heat exchanger 02, a bypass pipeline 03, a main oil supply pipeline 04, a main oil return pipeline 05, and a heat-using device 06. Heat exchanger 02 is connected in main pipeline 01. One end of main pipeline 01 is connected to the oil inlet of heat device 06 through main oil supply pipeline 04, and the other end is connected to the oil outlet of heat device 06 through main oil return pipeline 05. Bypass pipeline 03 is connected in parallel to both ends of main pipeline 01. It also includes steam regulating valve 08, temperature controller 07, and steam valve position controller 09; Steam regulating valve 08 is used to regulate the steam flow rate of heat exchanger 02; The temperature controller 07 obtains the outlet temperature and target outlet temperature of the heat medium in the main oil supply pipeline 04 at its input terminal, and outputs the temperature control value after determining the temperature control value based on the outlet temperature and target outlet temperature. The input terminal of the steam valve position controller 09 is connected to the output terminal of the temperature controller 07 to obtain the temperature control value. Based on the temperature control value and the preset valve position value, the opening degree of the steam regulating valve 08 is determined and output from the output terminal. The output terminal of the steam valve position controller 09 is connected to the steam regulating valve 08.

[0024] Specifically, one end of the main pipeline 01 is connected to the oil inlet of the heat-using device 06 via the main oil supply pipeline 04, and the other end is connected to the oil outlet of the heat-using device 06 via the main oil return pipeline 05. The heat exchanger 02 is connected in the main pipeline 01, while the bypass pipeline 03 is connected in parallel at both ends of the main pipeline 01. After the heat medium flows out of the heat-using device 06, it flows along the main oil return pipeline 05 to the main pipeline 01, and splits at the parallel connection of the bypass pipeline 03. The two heat media flow through the heat exchanger 02 and the bypass pipeline 03 in the main pipeline 01, respectively. The heat medium flowing through the heat exchanger 02 and the other heat medium flowing through the bypass pipeline 03 re-merge at the beginning of the main oil supply pipeline 04 and flow to the heat-using device 06.

[0025] The input terminal of the temperature controller 07 is connected to the main oil supply pipeline 04 to obtain the outlet temperature of the heat medium, and to determine the temperature control value based on the outlet temperature of the heat medium and the preset target outlet temperature, and output the temperature control value from the output terminal. The target outlet temperature can be input into the temperature controller 07, or it can be input through other devices connected to the input terminal of the temperature controller 07.

[0026] The input terminal of the steam valve position controller 09 is connected to the output terminal of the temperature controller 07 to obtain the temperature control value. Based on the temperature control value and the preset valve position value, the opening degree of the steam regulating valve 08 is determined and the opening degree of the steam regulating valve 08 is output from the output terminal. The output terminal of the steam valve position controller 09 is connected to the steam regulating valve 08, and the steam regulating valve 08 is used to regulate the steam flow of the heat exchanger 02.

[0027] In this embodiment, the temperature controller 07 outputs a temperature control value after determining the temperature control value based on the outlet temperature of the heat medium in the main oil supply pipeline 04 and the preset target outlet temperature. The input terminal of the steam valve position controller 09 is connected to the output terminal of the temperature controller 07. After obtaining the temperature control value, it determines the opening degree of the steam regulating valve 08 based on the temperature control value and the preset valve position value, and controls the steam regulating valve 08 to regulate the steam flow rate of the heat exchanger 02. This embodiment controls the steam flow rate, which can gradually reduce the steam load of the heat bypass system when the heat medium temperature needs to be reduced. This solves the problem in the prior art where a large amount of heat medium flows through the bypass pipeline 03 but a large amount of steam is still introduced into the heat exchanger 02 for heating when the heat medium temperature is reduced, thereby reducing energy consumption, saving production costs, and protecting the mechanical integrity of the heat exchanger 02 from dry burning damage. When the heat medium temperature needs to be adjusted, the system response speed can be accelerated by simultaneously adjusting the heat medium flow rate and steam flow rate of the main bypass.

[0028] In one embodiment, the temperature controller 07 is specifically used for: The heat transfer medium outlet temperature is compared with the preset target outlet temperature, and the temperature control value is output based on the temperature difference between the heat transfer medium outlet temperature and the target outlet temperature. Steam valve position controller 09 is specifically used for: The temperature control value is compared with the preset valve position value, and the opening of the steam regulating valve 08 is adjusted according to the relationship between the temperature control value and the preset valve position value.

[0029] In this embodiment, the temperature control value is determined by the temperature difference between the heat medium outlet temperature and the target outlet temperature. If the heat medium outlet temperature is higher than the target outlet temperature, it indicates that the heat medium needs to be cooled down. At this time, the temperature control value increases. After receiving the temperature control value, the steam valve position controller 09 compares it with the preset valve position value. If the temperature control value is not equal to the preset valve position value, the opening of the steam regulating valve 08 is adjusted and output according to the relationship between the temperature control value and the preset valve position value.

[0030] In a preferred embodiment, the opening of the steam regulating valve 08 is adjusted according to the relationship between the temperature control value and the preset valve position value, specifically including: If the temperature control value is equal to the preset valve position value, the opening of the steam regulating valve 08 will not be adjusted. If the temperature control value is greater than the preset valve position value, the opening of the steam regulating valve 08 will be continuously reduced at a preset rate. If the temperature control value is less than the preset valve position value, the opening of the steam regulating valve 08 will be continuously increased at the preset rate.

[0031] In this embodiment, the steam valve position controller 09 continuously compares the temperature control value with the preset valve position value. If the temperature control value is equal to the preset valve position value, the opening of the steam regulating valve 08 is not adjusted. If the temperature control value is not equal to the preset valve position value, the opening of the steam regulating valve 08 is adjusted at the same preset rate according to the relationship between the two values ​​until the temperature control value is equal to the preset valve position value, at which point the adjustment of the opening of the steam regulating valve 08 is stopped.

[0032] Specifically, in steady state, the temperature control value is equal to the preset valve position value. When it is necessary to reduce the outlet temperature of the heat medium, the outlet temperature of the heat medium is higher than the target outlet temperature. At this time, the temperature control value will increase. The steam valve position controller 09 detects that the temperature control value is greater than the preset valve position value, and will continuously reduce the opening of the steam regulating valve 08 at a preset rate, thereby slowly reducing the steam flow through the heat exchanger 02, saving production costs, reducing energy consumption, and preventing the heat exchanger 02 from being heated by a large amount of steam, thus protecting the mechanical integrity of the heat exchanger 02. This allows the temperature of the heat medium flowing through the heat exchanger 02 to decrease more quickly, improving the system's response speed.

[0033] When it is necessary to raise the outlet temperature of the heat medium, if the outlet temperature of the heat medium is lower than the target outlet temperature, the temperature control value will decrease. If the steam valve position controller 09 detects that the temperature control value is less than the preset valve position value, it will continuously increase the opening of the steam regulating valve 08 at a preset rate, thereby increasing the steam flow through the heat exchanger 02, so that the temperature of the heat medium flowing through the heat exchanger 02 can rise more quickly and improve the system response speed.

[0034] In one embodiment, it also includes a heat medium regulating valve assembly, a flow controller 10, and a heat medium controller; The heat medium regulating valve assembly is used to regulate the heat medium flow rate between the main pipeline 01 and the bypass pipeline 03; The input terminal of the flow controller 10 obtains the total flow rate of the heat medium in the return oil main pipeline 05, and outputs the flow rate value from the output terminal after determining the total flow rate of the heat medium. The input terminal of the heat medium controller is connected to the output terminal of the temperature controller 07 and the output terminal of the flow controller 10. It is used to obtain the temperature control value and the flow rate value, and to determine the opening degree of the heat medium regulating valve group based on the temperature control value and the flow rate value before outputting it from the output terminal. The output terminal of the heat medium controller is connected to the heat medium regulating valve group.

[0035] In this embodiment, the heat medium regulating valve group is used to regulate the flow rate of the heat medium flowing through the main pipeline 01 and the bypass pipeline 03. The flow controller 10 determines the flow rate value based on the total flow rate of the heat medium obtained in the return oil main pipeline 05 and outputs it at the output end. After receiving the temperature control value and the flow rate value, the heat medium controller determines the opening degree of the heat medium regulating valve group based on the temperature control value and the flow rate value and outputs it from the output end. The output end of the heat medium controller is connected to the heat medium regulating valve group, thereby adjusting the heat medium temperature of the heat-using device 06. In the initial stage of temperature adjustment, it is necessary to quickly adjust the heat medium outlet temperature to the required target outlet temperature. The heat medium regulating valve group can react quickly to make the heat medium outlet temperature tend to be consistent with the target outlet temperature.

[0036] The heat medium regulating valve assembly can be a three-way regulating valve or two valves that control the main pipeline and the bypass pipeline respectively.

[0037] In one embodiment, the heat medium regulating valve group includes a bypass regulating valve 12 and a main regulating valve 14. The bypass regulating valve 12 is connected in the bypass pipe 03 and is used to control the flow rate of the heat medium flowing through the bypass pipe 03. The main regulating valve 14 is in the main pipe 01 and is used to control the flow rate of the heat medium flowing through the heat exchanger 02. The heat medium controller is specifically used for: The opening degree of the bypass regulating valve 12 is determined based on the temperature control value and the flow rate value; The opening degree of the main control valve 14 is determined based on the flow rate value and the opening degree of the bypass control valve 12.

[0038] In this embodiment, the heat medium regulating valve group includes a bypass regulating valve 12 and a main regulating valve 14, which are used to control the flow rate of the heat medium flowing through the bypass pipe 03 and the heat exchanger 02, respectively. After receiving the temperature control value and the flow rate value, the heat medium controller determines the opening degree of the bypass regulating valve 12 based on the temperature control value and the flow rate value and controls it accordingly. The opening degree of the main regulating valve 14 is determined based on the flow rate value and the opening degree of the bypass regulating valve 12.

[0039] In a preferred embodiment, the heat medium regulating valve group includes two valves that control the flow of heat medium in the main pipeline 01 and the bypass pipeline 03 respectively. By selecting two valves to control the main and bypass pipelines respectively, large flow fluctuations can be avoided during temperature regulation, thereby maintaining the stability of the total flow of heat medium.

[0040] When the outlet temperature of the heat medium differs from the target outlet temperature, the temperature control value changes, while the flow rate value remains unchanged by default. Consequently, the opening of the bypass regulating valve 12 also changes, and the opening of the main regulating valve 14 changes along with the opening of the bypass regulating valve 12. This regulates the flow rate of the heat medium through the main pipeline 01 and the bypass pipeline 03, thereby rapidly adjusting the outlet temperature of the heat medium to make it approach the target outlet temperature.

[0041] In one embodiment, the heat medium controller includes a bypass controller 11; The input terminal of the bypass controller 11 is connected to the output terminal of the temperature controller 07 and the output terminal of the flow controller 10. It is used to obtain the temperature control value and the flow rate value, and to determine the opening degree of the bypass regulating valve 12 based on the temperature control value and the flow rate value before outputting it from the output terminal. The output terminal of the bypass controller 11 is connected to the bypass regulating valve 12.

[0042] In this embodiment, the bypass controller 11 is connected to the output of the temperature controller 07 and the output of the flow controller 10, respectively, to obtain the temperature control value and the flow rate value, and to determine the opening degree of the bypass regulating valve 12 based on the two values ​​and output it from the output. The bypass regulating valve 12 is connected to the output of the bypass controller 11, thereby achieving the function of adjusting the flow rate of the heat medium flowing through the bypass pipe 03 according to the required target outlet temperature.

[0043] Specifically, the output value of the bypass controller 11 changes with the temperature control value and the flow rate value. However, under normal circumstances, the total flow rate of the heat medium flowing through the heat exchanger 02 and the bypass pipe 03 remains unchanged, that is, the flow rate value remains unchanged. Therefore, the output value of the bypass controller 11 only changes with the temperature control value. The output value of the bypass controller 11 is used to control the opening of the bypass regulating valve 12. When the opening of the bypass regulating valve 12 is adjusted, the outlet temperature of the heat medium gradually tends to be equal to the target outlet temperature. Then, the temperature control value tends to be equal to the preset valve position value. At this time, the opening of the bypass regulating valve 12 changes with the temperature control value.

[0044] In one embodiment, the bypass controller calculates the opening degree of the bypass regulating valve according to the following formula: (1) Where c is the opening degree of the bypass control valve, k is the flow coefficient of the main control valve and the bypass control valve under the design operating conditions, a is the flow value, and b is the temperature control value. Calculate the value of k using the following formula: (2) Wherein, CV1 is the flow coefficient of the bypass control valve, CV2 is the flow coefficient of the main control valve, ΔP1 is the pressure drop of the bypass control valve, and ΔP2 is the pressure drop of the main control valve.

[0045] In this embodiment, it is necessary to first determine the flow coefficient k values ​​of the main control valve 14 and the bypass control valve 12 under the design operating conditions. The k value is a compensation factor for the flow difference caused by the valve size and pressure drop distribution of the main control valve 14 and the bypass control valve 12. It can be determined based on the flow coefficient CV1 of the bypass control valve 12, the flow coefficient CV2 of the main control valve 14, and their respective pressure drops. CV1 and CV2 are the characteristic data of the valves, which can be obtained from the information provided by the manufacturer.

[0046] The opening degree of the bypass regulating valve 12 is calculated based on the flow rate value received from the flow controller 10, the temperature control value received from the temperature controller 07, and the value of k. In this embodiment, the value of k can be calculated first according to different systems, and then the opening degree of the bypass regulating valve 12 can be calculated based on the output values ​​of the flow controller 10 and the temperature controller 07. It has high applicability and can be applied to systems with different valves and different pipe shapes.

[0047] In one embodiment, the heat medium controller further includes a main circuit controller 13; The input terminal of the main controller 13 is connected to the output terminal of the flow controller 10 and the output terminal of the bypass controller 11. It is used to obtain the flow value and the opening degree of the bypass regulating valve 12, and to determine the opening degree of the main regulating valve 14 based on the flow value and the opening degree of the bypass regulating valve 12 before outputting it from the output terminal. The output terminal of the main controller 13 is connected to the main regulating valve 14.

[0048] In this embodiment, the main controller 13 is connected to the output terminal of the flow controller 10 and the output terminal of the bypass controller 11. It is used to obtain the flow rate value and the opening degree of the bypass regulating valve 12, and to determine the opening degree of the main regulating valve 14 based on the two values ​​and output it from the output terminal. The output terminal of the main controller 13 is connected to the main regulating valve 14 and is used to control the opening degree adjustment of the main regulating valve 14.

[0049] Specifically, the output value of the main controller 13 changes with the flow rate and the opening of the bypass regulating valve 12. However, under normal circumstances, the total flow rate of the heat medium flowing through the heat exchanger 02 and the bypass pipe 03 remains unchanged, that is, the flow rate remains unchanged. Therefore, the output value of the main controller 13 changes with the opening of the bypass regulating valve 12, and the opening of the bypass regulating valve 12 changes with the temperature control value. When the bypass regulating valve 12 and the main regulating valve 14 are adjusted, the temperature control value tends to be equal to the preset valve position value. Therefore, the opening of the main regulating valve 14 will also change with the temperature control value.

[0050] In another embodiment, the output value of the main circuit controller 13 can be directly derived from the output value of the bypass controller 11.

[0051] In one embodiment, the main circuit controller 13 calculates the opening degree of the main circuit regulating valve 14 according to the following formula: (3) Where d is the opening degree of the main control valve, a is the flow rate value, c is the opening degree of the bypass control valve, and k is the flow coefficient of the main control valve and the bypass control valve under the design operating conditions.

[0052] In this embodiment, the main control controller can calculate the opening degree of the main control valve based on the k value, the flow rate received from the flow controller, and the output value of the bypass controller. Substituting the k value again, instead of directly calculating the opening degree of the main control valve based on the opening degree of the bypass control valve, the calculation accuracy of this system is increased.

[0053] Assuming that the output values ​​of temperature controller 07 are b0 and b1 at the initial time and at any other time, the opening degrees of bypass regulating valve 12 are c0 and c1, and the opening degrees of main regulating valve 14 are d0 and d1, then: c0=(1+k)ab0 c1=(1+k)ab1 d0=a(1+k)-kc0 d1=a(1+k)-kc1 Substituting the values ​​into the calculation, we get: Δc = c1 - c0 = (1 + k)a(b1 - b0) Δd = d1 - d0 = -(1 + k)ak(b1 - b0) It can be known that: kΔc+Δd=0 Regardless of the initial values ​​of k and a, the flow rate change through the bypass regulating valve 12 can be kept consistent with the flow rate change through the main regulating valve 14 during the change of b value, thus eliminating the coupling between flow rate and temperature control and ensuring a constant total flow rate of the hot oil system.

[0054] In one embodiment, a user input device is also included, the output of which is connected to the input of the temperature controller 07 and the input of the steam valve position controller 09, for inputting the target outlet temperature and / or preset valve position value and / or preset rate.

[0055] In this embodiment, the system also includes a user input device. The user can input the target outlet temperature into the temperature controller 07 and preset the valve position value and / or preset rate into the steam valve position controller 09 according to production needs. The user can adjust the heat medium outlet temperature at any time using the steam regulating valve 08.

[0056] As an example, consider the hot oil system of a carbomer unit: To ensure that both the bypass regulating valve 12 and the main regulating valve 14 have significant regulating capacity, the preset valve position value is set to 50%. Based on data calculations, the k value for this system is 0.36. During system temperature adjustment, the total flow rate remains constant, meaning the flow rate value a remains unchanged.

[0057] During the high-temperature operation phase, the target outlet temperature is 180℃. When the steady state is reached, the heat medium outlet temperature is consistent with the target outlet temperature and stabilizes at 180℃. At this time, the temperature control value b output by the temperature controller 07 is equal to the preset valve position value of the steam valve position controller 09, which is 50%. The flow rate value a output by the flow controller 10 is 0.4. Then, the opening degree c of the bypass regulating valve 12 is 27.2%, the opening degree d of the main regulating valve 14 is 44.6%, and the opening degree of the steam regulating valve 08 is 78%.

[0058] In the initial stage of low-temperature operation, the target outlet temperature is 120℃. The outlet temperature of the heat medium is higher than the target outlet temperature, so the temperature control value b increases to 0.7, which causes the opening degree c of the bypass regulating valve 12 to increase to 0.286 and the opening degree d of the main regulating valve 14 to decrease to 0.407. At this time, the flow rate of the heat medium flowing through the bypass pipe 03 without passing through the heat exchanger 02 increases, so the outlet temperature of the heat medium decreases rapidly and tends to be consistent with the target outlet temperature.

[0059] At the same time, the steam valve position controller 09 receives an increase in the temperature control value b, which is greater than the preset valve position value of the steam valve position controller 09. As a result, the opening of the steam regulating valve 08 decreases at a preset rate to reduce the steam flow in the heat exchanger 02. This will also cause the outlet temperature of the heat medium to drop. However, since this adjustment process is a pure integral or weak proportional + large integral PID tuning strategy, this process is slow enough.

[0060] As the outlet temperature of the heat medium decreases, the deviation between the outlet temperature and the target outlet temperature decreases, and the temperature control value gradually decreases. Consequently, the opening of the bypass regulating valve 12 increases rapidly and then slowly decreases, while the opening of the main regulating valve 14 decreases rapidly and then slowly increases. Meanwhile, the opening of the steam regulating valve 08 continues to slowly decrease. This continues until the outlet temperature of the heat medium equals the target outlet temperature, and the temperature control value and the preset valve position value become consistent again, thus reaching a new steady state.

[0061] At this time, the temperature control value received by the steam valve position controller 09 is consistent with the preset valve position value. Since the flow rate value a remains unchanged, it means that the opening of the bypass regulating valve 12 and the main regulating valve 14 has returned to the valve opening corresponding to the previous adjustment, that is, the valve opening of each valve is 27.2% and 44.6% respectively during the high temperature operation stage, and the opening of the steam regulating valve 08 is reduced and stabilized at 56%.

[0062] It can be seen that the bypass regulating valve 12 and the main regulating valve 14 only respond quickly in the initial reaction stage, and quickly adjust the flow rate of the heat medium flowing through the bypass pipe 03 and the main pipe 01 to quickly lower or raise the outlet temperature of the heat medium. Then, under the action of the steam valve position controller 09, the steam regulating valve 08 gradually closes or opens to match the steam heat load at the current set temperature, while the bypass regulating valve 12 and the main regulating valve 14 slowly return to their original opening degree to prepare for the next load adjustment.

[0063] After implementing this scheme, based on the following parameters for the hot oil system of the Carbomer unit: flow rate of 300 m3 / h, density of 800 kg / m3, specific heat capacity of 2.1 kJ / (kg·℃), latent heat of vaporization of S30 steam of 1782 kJ / kg, price of 230 yuan / t, annual production of 8000 h, and calculation that the hot oil system operates at low temperature for 75% of the production cycle, the hot oil system can save 101,600 t / year of steam and save 23.37 million yuan / year of steam energy costs.

[0064] The above description is merely the principle and preferred embodiment of this application. It should be noted that for those skilled in the art, implementation methods obtained by appropriately combining the technical solutions disclosed in different embodiments are also included within the technical scope of this invention. Based on the principle of this application, several other modifications can also be made, which should also be considered within the protection scope of this application.

Claims

1. A thermal bypass temperature control system, the system comprising a main pipeline, a heat exchanger, a bypass pipeline, a main oil supply pipeline, a main oil return pipeline, and a heat-using device; The heat exchanger is connected in the main pipeline. One end of the main pipeline is connected to the oil inlet of the heat-using device through the main oil supply pipeline, and the other end is connected to the oil outlet of the heat-using device through the main oil return pipeline. The bypass pipeline is connected in parallel to both ends of the main pipeline. Its features are, It also includes steam regulating valves, temperature controllers, and steam valve position controllers; The steam regulating valve is used to regulate the steam flow rate of the heat exchanger; The temperature controller obtains the outlet temperature of the heat medium and the target outlet temperature in the main oil supply pipeline at its input terminal, and outputs the temperature control value after determining the temperature control value based on the heat medium outlet temperature and the target outlet temperature. The input terminal of the steam valve position controller is connected to the output terminal of the temperature controller to obtain the temperature control value, and after determining the opening degree of the steam regulating valve according to the temperature control value and the preset valve position value, output it from the output terminal. The output terminal of the steam valve position controller is connected to the steam regulating valve. The system also includes a heat medium regulating valve assembly, a flow controller, and a heat medium controller; The input terminal of the flow controller acquires the total flow rate of the heat medium in the return oil main pipeline, and outputs the flow rate value from the output terminal after determining the total flow rate of the heat medium. The heat medium regulating valve group includes a bypass regulating valve and a main regulating valve. The bypass regulating valve is connected in the bypass pipeline and is used to control the flow rate of the heat medium flowing through the bypass pipeline. The main regulating valve is in the main pipeline and is used to control the flow rate of the heat medium flowing through the heat exchanger. The heat medium controller includes a bypass controller; The input terminal of the bypass controller is connected to the output terminal of the temperature controller and the output terminal of the flow controller. It is used to obtain the temperature control value and the flow rate value, and to determine the opening degree of the bypass regulating valve based on the temperature control value and the flow rate value before outputting it from the output terminal. The output terminal of the bypass controller is connected to the bypass regulating valve. The bypass controller calculates the opening degree of the bypass regulating valve according to the following formula: （1） Where c is the opening degree of the bypass regulating valve, k is the flow coefficient of the main regulating valve and the bypass regulating valve under the design operating conditions, a is the flow value, and b is the temperature control value; Calculate the value of k using the following formula: （2） Wherein, CV1 is the flow coefficient of the bypass control valve, CV2 is the flow coefficient of the main control valve, ΔP1 is the pressure drop of the bypass control valve, and ΔP2 is the pressure drop of the main control valve.

2. The thermal bypass temperature control system according to claim 1, characterized in that, The temperature controller is specifically used for: The heat medium outlet temperature is compared with the target outlet temperature, and the temperature control value is output based on the temperature difference between the heat medium outlet temperature and the target outlet temperature. The steam valve position controller is specifically used for: The temperature control value is compared with the preset valve position value, and the opening of the steam regulating valve is adjusted according to the relationship between the temperature control value and the preset valve position value.

3. The thermal bypass temperature control system according to claim 2, characterized in that, The step of adjusting the opening of the steam regulating valve according to the relationship between the temperature control value and the preset valve position value specifically includes: If the temperature control value is equal to the preset valve position value, then the opening of the steam regulating valve will not be adjusted. If the temperature control value is greater than the preset valve position value, the opening of the steam regulating valve will be continuously reduced at a preset rate. If the temperature control value is less than the preset valve position value, the opening of the steam regulating valve will be continuously increased at a preset rate.

4. The thermal bypass temperature control system according to claim 1, characterized in that, The heat medium regulating valve group is used to regulate the heat medium flow rate of the main pipeline and the bypass pipeline; The input terminal of the heat medium controller is connected to the output terminal of the temperature controller and the output terminal of the flow controller. It is used to obtain the temperature control value and the flow rate value, and to determine the opening degree of the heat medium regulating valve group based on the temperature control value and the flow rate value before outputting it from the output terminal. The output terminal of the heat medium controller is connected to the heat medium regulating valve group.

5. A thermal bypass temperature control system according to claim 4, characterized in that, The heat medium controller is specifically used for: The opening degree of the bypass regulating valve is determined based on the temperature control value and the flow rate value; The opening degree of the main control valve is determined based on the flow rate value and the opening degree of the bypass control valve.

6. A thermal bypass temperature control system according to claim 5, characterized in that, The heat medium controller also includes a main circuit controller; The input terminal of the main circuit controller is connected to the output terminal of the flow controller and the output terminal of the bypass controller. It is used to obtain the flow rate value and the opening degree of the bypass regulating valve, and to determine the opening degree of the main circuit regulating valve based on the flow rate value and the opening degree of the bypass regulating valve before outputting it from the output terminal. The output terminal of the main circuit controller is connected to the main circuit regulating valve.

7. A thermal bypass temperature control system according to claim 6, characterized in that, The main circuit controller calculates the opening degree of the main circuit regulating valve according to the following formula: （3） Wherein, d is the opening degree of the main regulating valve, a is the flow rate value, c is the opening degree of the bypass regulating valve, and k is the flow coefficient of the main regulating valve and the bypass regulating valve under the design operating conditions.

8. A thermal bypass temperature control system according to any one of claims 1-7, characterized in that, It also includes a user input device, the output of which is connected to the input of the temperature controller and the input of the steam valve position controller, for inputting the target outlet temperature and / or the preset valve position value.

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