CN111256500A

CN111256500A - Method for controlling flow rate of four-fluid heat exchanger with three valves to be opened and closed

Info

Publication number: CN111256500A
Application number: CN202010074156.XA
Authority: CN
Inventors: 王逸隆; 籍艳
Original assignee: Qingdao University of Science and Technology
Current assignee: Qingdao University of Science and Technology
Priority date: 2020-01-21
Filing date: 2020-01-21
Publication date: 2020-06-09

Abstract

The invention provides a method for controlling a four-fluid heat exchanger with three valves to be opened and closed by flow rate, wherein inlets of a first heat exchange tube, a second heat exchange tube and a third heat exchange tube are provided with a first valve, a second valve and a third valve, a speed sensing element is arranged in a free end of a tube bundle and used for detecting the flow rate of fluid in the free end of the tube bundle, the speed sensing element is in data connection with a controller, and the controller is used for opening and closing the first valve, the second valve and the third valve according to the detected speed of the fluid so as to control whether the first fluid, the third fluid and the second fluid exchange heat or not. The invention starts new fluid to perform alternate heat exchange by detecting the change of the detection speed, thereby continuously driving the vibration of the elastic tube bundle, and further realizing the heat exchange efficiency and the descaling operation.

Description

Method for controlling flow rate of four-fluid heat exchanger with three valves to be opened and closed

Technical Field

The present invention is a further improvement over the previous applications, which is applied to the field of heat exchangers. The invention relates to a shell-and-tube heat exchanger, in particular to a shell-and-tube heat exchanger for gas heat exchange.

Background

The invention relates to heat exchanger descaling, which is a novel invention applied to a shell-and-tube heat exchanger on the basis of research and development of Qingdao science and technology university (application number 2019101874848).

The shell-and-tube heat exchanger is widely applied to industries such as chemical industry, petroleum industry, refrigeration industry, nuclear energy industry and power industry, and due to the worldwide energy crisis, the demand of the heat exchanger in industrial production is more and more, and the quality requirement of the heat exchanger is higher and more. In recent decades, although compact heat exchangers (plate type, plate fin type, pressure welded plate type, etc.), heat pipe type heat exchangers, direct contact type heat exchangers, etc. have been rapidly developed, because the shell and tube type heat exchangers have high reliability and wide adaptability, they still occupy the domination of yield and usage, and according to relevant statistics, the usage of the shell and tube type heat exchangers in the current industrial devices still accounts for about 70% of the usage of all heat exchangers.

After the shell-and-tube heat exchanger is scaled, the heat exchanger is cleaned by adopting conventional modes of steam cleaning, back flushing and the like, and the production practice proves that the effect is not good. The end socket of the heat exchanger can only be disassembled, and a physical cleaning mode is adopted, but the mode is adopted for cleaning, so that the operation is complex, the consumed time is long, the investment of manpower and material resources is large, and great difficulty is brought to continuous industrial production.

The mode of passively strengthening heat exchange is to strictly prevent the fluid vibration induction in the heat exchanger from being changed into effective utilization of vibration, so that the convective heat transfer coefficient of the transmission element at low flow speed is greatly improved, dirt on the surface of the heat transfer element is restrained by vibration, the thermal resistance of the dirt is reduced, and the composite strengthened heat transfer is realized.

In application, it is found that continuous heating can cause the internal fluid to form stability, i.e. the fluid does not flow or has little fluidity, or the flow is stable, so that the vibration performance of the heat exchange tube is greatly weakened, thereby affecting the descaling of the heat exchange tube and the heating efficiency. There is therefore a need for improvements to the above-described heat exchangers.

The heat exchanger generally exchanges heat by two fluids, and the heat exchange of four fluids is rarely researched, the four-fluid heat exchange is researched, a novel induced vibration four-fluid shell-and-tube heat exchanger is developed,

current shell and tube heat exchangers include dual headers, one header evaporating and one header condensing, thereby forming a vibrating descaled heat pipe. Thereby improving the heat exchange efficiency of the heat pipe and reducing scaling. However, the heat pipe has insufficient uniformity of heat exchange, only one side is used for condensation, and the heat exchange amount is small, so that improvement is needed to develop a heat pipe system with a novel structure. There is therefore a need for improvements to the above-described heat exchangers.

In the prior application, a shell-and-tube heat exchanger for exchanging heat of four fluids has been developed, but the shell-and-tube heat exchanger is controlled according to the period, so that the vibration heat exchange effect is poor, and the intelligent degree is low. The present application therefore provides further improvements over the previous studies.

Disclosure of Invention

The invention provides a four-fluid shell-and-tube heat exchanger with a novel structure aiming at the defects of a shell-and-tube heat exchanger in the prior art. The shell-and-tube heat exchanger can realize heat exchange of four fluids, and the periodic frequent vibration of the heat exchange tubes improves the heating efficiency, thereby realizing good descaling and heating effects.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for controlling the flow rate of a four-fluid heat exchanger with three valves to be opened and closed comprises a shell, a heat exchange part, a shell side inlet connecting pipe and a shell side outlet connecting pipe; the heat exchange component is arranged in the shell and fixedly connected to the front tube plate and the rear tube plate; the shell pass inlet connecting pipe and the shell pass outlet connecting pipe are both arranged on the shell; the shell pass fluid enters from a shell pass inlet connecting pipe, exchanges heat through the heat exchange part and exits from a shell pass outlet connecting pipe;

the heat exchanger also comprises a first heat exchange tube, a second heat exchange tube and a third heat exchange tube, wherein the first heat exchange tube penetrates through the left side tube, the second heat exchange tube penetrates through the central tube, and the third heat exchange tube penetrates through the right side tube; the first heat exchange tube, the second heat exchange tube and the third heat exchange tube respectively flow through a first fluid, a second fluid and a third fluid;

the inlets of the first heat exchange tube, the second heat exchange tube and the third heat exchange tube are provided with a first valve, a second valve and a third valve which are in data connection with the controller;

the device is characterized in that a speed sensing element is arranged in the free end of the tube bundle and used for detecting the flow speed of fluid in the free end of the tube bundle, the speed sensing element is in data connection with a controller, and the controller controls the first valve, the second valve and the third valve to be opened and closed according to the detected speed of the fluid, so that whether the first fluid, the third fluid and the second fluid exchange heat or not is controlled.

Preferably, when the first and third fluids exchange heat and the second fluid does not exchange heat, if the speed detected by the speed sensing element is higher than a certain value, the controller controls the first and third valves to be closed and the second valve to be opened, so that the first and third fluids stop exchanging heat and the second fluid exchanges heat; when the first fluid and the third fluid stop exchanging heat and the second fluid exchanges heat, if the speed detected by the speed sensing element is higher than a certain value, the controller controls the first valve and the third valve to be opened and the second valve to be closed, so that the first fluid and the third fluid exchange heat and the second fluid stops exchanging heat.

The heat exchange component comprises a central tube, a left tube, a right tube and tube groups, wherein the tube groups comprise a left tube group and a right tube group, the left tube group is communicated with the left tube and the central tube, the right tube group is communicated with the right tube and the central tube, so that the central tube, the left tube, the right tube and the tube groups form heating fluid closed circulation, the left tube and/or the central tube and/or the right tube are filled with phase-change fluid, each tube group comprises a plurality of circular arc-shaped annular tubes, the end parts of the adjacent annular tubes are communicated, the annular tubes form a serial structure, and the end parts of the annular tubes form free ends of the annular tubes; the central tube comprises a first tube orifice and a second tube orifice, the first tube orifice is connected with the inlet of the left tube group, the second tube orifice is connected with the inlet of the right tube group, the outlet of the left tube group is connected with the left tube, and the outlet of the right tube group is connected with the right tube; the first pipe orifice and the second pipe orifice are arranged on the same side of the central pipe; the position of the right tube group is the position of the left tube group after rotating 180 degrees along the axis of the central tube;

a left return pipe is arranged between the left side pipe and the central pipe, and a right return pipe is arranged between the right side pipe and the central pipe.

The invention has the following advantages:

1. according to the invention, the speed detected by the speed sensing element can ensure that the evaporation of the internal fluid is basically saturated to form stable flow under the condition of meeting a certain speed (such as the highest upper limit), and the speed of the internal fluid is basically not changed greatly. And new fluid is started to perform alternate heat exchange by detecting the speed change, so that the heat exchange effect and the descaling effect are improved.

2. According to the invention, through the intelligent opening and closing of the first valve, the second valve and the third valve under the control of temperature, on one hand, continuous heat exchange is realized for the shell pass process, and meanwhile, the elastic heat exchange tube can vibrate periodically and frequently, so that good descaling and heat exchange effects are realized.

3. According to the invention, through controlling the intermittent flow of the first fluid, the second fluid and the third fluid, continuous heat exchange is carried out on the shell process flow, and meanwhile, the elastic heat exchange tube can periodically and frequently vibrate, so that good descaling and heat exchange effects are realized.

4. The invention designs that the flowing directions of the first fluid, the third fluid and the second fluid are opposite, and further promotes the flowing of the phase-change fluid, thereby enhancing the heat transfer.

5. The invention designs a layout of a heat exchange component with a novel structure in a shell, optimizes the optimal relation between the parameters of the heat exchange tube and the flow, specific heat and the like of the fluid through a large number of experiments and numerical simulation, and creatively integrates the flow, the specific heat, the temperature and the target temperature of the heat exchange fluid into the size design of the heat exchanger relative to the previous design, thereby further improving the heat exchange efficiency.

6. Through the flowing direction of fluid in the shell, the reasonable change of the internal diameter and the interval of the tube bundle of the heat exchange tube improves the heat exchange efficiency.

Description of the drawings:

fig. 1 is a schematic structural view of a heat exchanger according to the present invention.

FIG. 2 is a schematic sectional view of a heat exchange member according to the present invention.

Fig. 3 is a top view of a heat exchange member.

Fig. 4 is a schematic diagram of a preferred structure of the heat exchanger.

Fig. 5 is another preferred schematic construction of the heat exchanger.

Fig. 6 is a schematic layout of heat exchange components arranged in a circular shell.

Fig. 7 is a schematic diagram of a preferred structure of the heat exchanger.

Fig. 8 is another preferred schematic construction of the heat exchanger.

In the figure: 1. tube group, left tube group 11,

right tube group

12, 21, left tube, 22, right tube, 3, free end, 4, free end, 5, free end, 6, free end, 7, annular tube, 8, center tube, 91-93, heat exchange tube, 10 first orifice, 13 second orifice, left return tube 14, right return tube 15, front tube plate 16, support 17, support 18, rear tube plate 19,

shell

20, 21, shell inlet connection, 22, shell outlet connection, 23, heat exchange component, 24 first valve, 25 second valve, 26 third valve, 27 inlet header, 28 outlet header

Detailed Description

A shell-and-tube heat exchanger, as shown in fig. 1, comprises a shell 20, a heat exchange component 23, a shell-side inlet connecting pipe 21 and a shell-side outlet connecting pipe 22; the heat exchange component 23 is arranged in the shell 20 and fixedly connected to the front tube plate 16 and the rear tube plate 19; the shell side inlet connecting pipe 21 and the shell side outlet connecting pipe 22 are both arranged on the shell 20; fluid enters from the shell side inlet connecting pipe 21, exchanges heat through the heat exchange part and exits from the shell side outlet connecting pipe 22.

Preferably, the heat exchange member extends in a vertical direction. The heat exchanger is arranged in the vertical direction.

Preferably, the shell-side fluid is a gas. The gas is preferably air, or carbon dioxide gas.

Fig. 2 shows a top view of a heat exchange part 23, which comprises a central tube 8, a left tube 21, a right tube 22 and tube groups 1, wherein the tube groups 1 comprise a left tube group 11 and a right tube group 12, the left tube group 11 is communicated with the left tube 21 and the central tube 8, the right tube group 12 is communicated with the right tube 22 and the central tube 8, so that the central tube 8, the left tube 21, the right tube 22 and the tube groups 1 form a closed circulation of heating fluid, the left tube 21 and/or the central tube 8 and/or the right tube 22 are filled with phase change fluid, each tube group 1 comprises a plurality of circular tubes 7 in the shape of circular arcs, the ends of the adjacent circular tubes 7 are communicated, so that the plurality of circular tubes 7 form a serial structure, and the ends of the circular tubes 7 form free ends 3-6 of the circular tubes; the central tube comprises a first tube orifice 10 and a second tube orifice 13, the first tube orifice 10 is connected with the inlet of the left tube group 11, the second tube orifice 13 is connected with the inlet of the right tube group 12, the outlet of the left tube group 11 is connected with the left tube 21, and the outlet of the right tube group 12 is connected with the right tube 22; the first orifice 10 and the second orifice 13 are arranged on the same side of the central tube 8. Preferably, the position of the right tube group is a position of the left tube group rotated by 180 degrees along the axis of the center tube.

The ends of the two ends of the central tube 8, the left tube 21 and the right tube 22 are arranged in the openings of the upper and

lower tube plates

16 and 19 for fixation. The first orifice 10 and the second orifice 13 are located on opposite sides of the central tube 8.

Preferably, a left return pipe 14 is arranged between the left pipe 21 and the central pipe 8, and a right return pipe 15 is arranged between the right pipe 22 and the central pipe 8. Preferably, the return pipe is arranged at the end of the central pipe. Preferably the bottom of the central tube.

The heat exchanger further comprises a first heat exchange tube 91, a second heat exchange tube 92 and a third heat exchange tube 93, wherein the first heat exchange tube 91 penetrates through the left side tube 21, the second heat exchange tube 92 penetrates through the central tube 8, and the third heat exchange tube 93 penetrates through the right side tube 22. The first heat exchange pipe 91, the second heat exchange pipe 92, and the third heat exchange pipe 93 flow a first fluid, a second fluid, and a third fluid, respectively. The first fluid, the second fluid, the third fluid and the shell side fluid can exchange heat among the four fluids. The four fluid heat sources can be 1-3, and the rest of the fluid is a cold source, or the cold source can be 1-3, and the rest of the fluid is a heat source.

As a preferred example of the heat exchange, for example, the heat exchange process is as follows:

the first fluid is a heat source, the second fluid, the third fluid and the shell pass fluid are cold sources, phase change fluid in the heat exchange component is subjected to phase change through heat exchange of the first fluid, so that the shell pass fluid is subjected to heat exchange through the annular pipe 7, meanwhile, vapor phase fluid enters the central pipe and the right side pipe to exchange heat with the second fluid and the third fluid, and condensed fluid after heat exchange returns to the right side pipe through the return pipe, so that heat exchange of the four fluids is realized.

Preferably, the third fluid and the second fluid are heat sources, the first fluid and the shell-side fluid are cold sources, and the phase-change fluid in the heat exchange part is subjected to phase change through heat exchange of the second fluid and the third fluid, so that the shell-side fluid is radiated outwards through the annular pipe 7, meanwhile, the vapor-phase fluid enters the left side pipe and exchanges heat with the first fluid, and the condensed fluid after heat exchange returns to the right pipe box through the return pipe, so that the four-fluid heat exchange is realized.

Preferably, the shell-side fluid is a heat source, the first fluid, the second fluid and the third fluid are cold sources, and the heat exchange of the shell-side fluid enables the fluid in the heat exchange component to absorb heat and exchange heat with the first fluid, the second fluid and the third fluid, so that the four-fluid heat exchange is realized.

Preferably, the first fluid and the third fluid are cold sources, the second fluid and the shell-side fluid are heat sources, and the heat exchange is realized through the second fluid and the shell-side fluid, so that the four-fluid heat exchange is realized.

Preferably, the second fluid is a cold source, the first fluid, the third fluid and the shell-side fluid are heat sources, and the second fluid is subjected to heat exchange through heat exchange of the first fluid, the third fluid and the shell-side fluid, so that four-fluid heat exchange is realized.

Preferably, the shell-side fluid is a cold source, the first fluid, the second fluid and the third fluid are heat sources, and the four-fluid heat exchange is realized by exchanging heat between the first fluid, the second fluid and the third fluid and the shell-side fluid.

Preferably, the first heat exchange tube, the second heat exchange tube and the third heat exchange tube have the same inner diameter.

Preferably, the fluid is a phase change fluid, preferably a vapour-liquid phase change fluid.

The following description focuses on the case where the shell-side fluid is the heat sink and the first fluid, the second fluid, and the third fluid are the heat sources.

The fluid is heated and evaporated in the central tube 8, flows to the left and

right headers

21 and 22 along the annular tube bundle, and is heated to expand in volume, so that steam is formed, and the volume of the steam is far larger than that of water, so that the formed steam can flow in the coil in a rapid impact manner. Because of volume expansion and steam flow, the free end of the annular tube can be induced to vibrate, the vibration is transmitted to the surrounding heat exchange fluid by the free end of the heat exchange tube in the vibration process, and the fluid can also generate disturbance, so that the surrounding heat exchange fluid forms disturbance flow, a boundary layer is damaged, and the purpose of enhancing heat transfer is realized. The fluid is condensed and released heat in the left and right side pipes and then flows back to the central pipe through the return pipe. Conversely, the fluid may be heated in the left and right pipes, condensed in the central pipe, and returned to the left and right pipes through the return pipe to be circulated.

According to the invention, the prior art is improved, and the condensation (evaporation) collecting pipe and the pipe groups are respectively arranged into two pipes which are distributed on the left side and the right side, so that the pipe groups distributed on the left side and the right side can perform vibration heat exchange descaling, the heat exchange vibration area is enlarged, the vibration is more uniform, the heat exchange effect is more uniform, the heat exchange area is increased, and the heat exchange and descaling effects are enhanced.

The flow rate in the present application is a flow rate per unit time, not specifically described. Unit is m³/s。

Preferably, as shown in fig. 7 and 8, the first valve 24, the second valve 25 and the third valve 26 are arranged at the inlets of the first heat exchange pipe 91, the second heat exchange pipe 92 and the third heat exchange pipe 93, the first valve 24, the second valve 25 and the third valve 26 are in data connection with a controller, and the controller controls the opening and closing and the opening of the first valve 24, the second valve 25 and the third valve 26 for controlling the flow of the heat exchange fluid entering the first heat exchange pipe 91, the second heat exchange pipe 92 and the third heat exchange pipe 93.

It has been found in research and practice that the heat exchange of the heat source with continuous power stability can cause the fluid forming stability of the internal heat exchange components, i.e. the fluid is not flowing or has little fluidity, or the flow rate is stable, and the vibration performance of the annular tubes 7 is greatly weakened, thereby affecting the descaling of the left tube group 11 and the right tube group 12 and the heat exchange efficiency. There is therefore a need for improvements to the heat exchangers described above as follows.

In the prior application of the inventor, a periodic heat exchange mode is provided, and the vibration of the annular tube is continuously promoted through the periodic heat exchange mode, so that the heat exchange efficiency and the descaling effect are improved. However, adjusting the vibration of the tube bundle with a fixed periodic variation can lead to hysteresis and too long or too short a period. Therefore, the invention improves the previous application and intelligently controls the vibration, so that the fluid in the fluid can realize frequent vibration, and good descaling and heat exchange effects are realized.

Aiming at the defects in the technology researched in the prior art, the invention provides a novel heat exchanger capable of intelligently controlling vibration. The heat exchanger can improve the heat exchange efficiency, thereby realizing good descaling and heat exchange effects.

Self-regulation vibration based on pressure

Preferably, a first pressure sensor, a second pressure sensor and a third pressure sensor are respectively arranged in the left tube 21, the central tube 8 and the right tube 22 and used for detecting the pressure in the left tube, the central tube and the right tube, the first pressure sensor, the second pressure sensor and the third pressure sensor are in data connection with a controller, and the controller controls the opening and closing of the first valve 24, the second valve 25 and the third valve 26 according to the detected pressure in the left tube, the right tube and the central tube, so as to control whether the first fluid, the third fluid and the second fluid exchange heat or not.

Preferably, when the first and third fluids exchange heat and the second fluid does not exchange heat, and when the pressure detected by the first or third pressure sensing element is higher than a certain value, or the average value of the pressures detected by the first and third pressure sensing elements is higher than a certain value, the controller controls the first and third valves to be closed and the second valve to be opened, so that the first and third fluids stop exchanging heat and the second fluid exchanges heat; when the first fluid and the third fluid stop heat exchange and the second fluid exchanges heat, and when the pressure detected by the second pressure sensing element is higher than a certain value, the controller controls the first valve and the third valve to be opened and the second valve to be closed, so that the first fluid and the third fluid exchange heat and the second fluid stops heat exchange.

Through the pressure that pressure perception element detected, can satisfy under certain pressure condition, the evaporation of the inside fluid of left side pipe, right side pipe or center tube has reached saturation basically, and the volume of inside fluid also changes little basically, and under this kind of condition, inside fluid is relatively stable, and the tube bank vibratility variation at this moment consequently needs to be adjusted, changes heat exchange component, makes the fluid flow towards different directions. Therefore, new fluid is started to perform alternate heat exchange by detecting the pressure change in the left side pipe, the right side pipe and the central pipe, and the heat exchange effect and the descaling effect are improved.

Independently adjusting vibration based on temperature

Preferably, a first temperature sensor, a second temperature sensor and a third temperature sensor are respectively arranged in the left tube 21, the central tube 8 and the right tube 22 and used for detecting the temperature in the left tube, the central tube and the right tube, the first temperature sensor, the second temperature sensor and the third temperature sensor are in data connection with a controller, and the controller controls the opening and closing of the first valve 24, the second valve 25 and the third valve 26 according to the detected temperature in the left tube, the right tube and the central tube, so as to control whether the first fluid, the third fluid and the second fluid exchange heat or not.

Preferably, when the first and third fluids exchange heat and the second fluid does not exchange heat, and when the temperature detected by the first or third temperature sensing element is higher than a certain value or the average value of the temperatures detected by the first and third temperature sensing elements is higher than a certain value, the controller controls the first and third valves to be closed and the second valve to be opened, so that the first and third fluids stop exchanging heat and the second fluid exchanges heat; when the first fluid and the third fluid stop heat exchange and the second fluid exchanges heat, and when the temperature detected by the second temperature sensing element is higher than a certain value, the controller controls the first valve and the third valve to be opened and the second valve to be closed, so that the first fluid and the third fluid exchange heat and the second fluid stops heat exchange.

The temperature that detects through temperature perception element can satisfy under certain temperature condition, the evaporation of the inside fluid of left side pipe, right side pipe or center tube has basically reached saturation, and the volume of inside fluid also changes little basically, and under this kind of condition, inside fluid is relatively stable, and the tube bank vibratility variation at this moment, consequently needs adjust, changes heat exchange component, makes the fluid flow towards different directions. Therefore, new fluid is started to perform alternate heat exchange by detecting the temperature change in the left side pipe, the right side pipe and the central pipe, and the heat exchange effect and the descaling effect are improved.

Thirdly, automatically adjusting vibration based on liquid level

Preferably, a first liquid level sensor, a second liquid level sensor and a third liquid level sensor are respectively arranged in the left side pipe 21, the central pipe 8 and the right side pipe 22 and used for detecting liquid levels in the left side pipe, the right side pipe and the central pipe, the first liquid level sensor, the second liquid level sensor and the third liquid level sensor are in data connection with a controller, and the controller controls the opening and closing of the first valve 24, the second valve 25 and the third valve 26 according to the detected liquid levels of the left side pipe, the right side pipe and the central pipe, so that whether the first fluid, the third fluid and the second fluid exchange heat or not is controlled.

Preferably, when the first and third fluids exchange heat and the second fluid does not exchange heat, and when the liquid level detected by the first or third liquid level sensing element is lower than a certain value, or the average value of the liquid levels detected by the first and third liquid level sensing elements is lower than a certain value, the controller controls the first valve and the third valve to be closed, and the second valve to be opened, so that the first and third fluids stop exchanging heat and the second fluid exchanges heat; when the first fluid and the third fluid stop heat exchange and the second fluid exchanges heat, and when the liquid level detected by the second liquid level sensing element is lower than a certain numerical value, the controller controls the first valve and the third valve to be opened and the second valve to be closed, so that the first fluid and the third fluid exchange heat and the second fluid stops heat exchange.

Through the liquid level that liquid level perception element detected, can satisfy under certain liquid level condition, the evaporation of the inside fluid of left side pipe, right side pipe or center tube has reached saturation basically, and the volume of inside fluid also changes little basically, and under this kind of condition, inside fluid is relatively stable, and the tube bank vibratility variation at this moment is consequently poor, consequently need adjust, changes heat exchange component, makes the fluid flow towards different directions. Therefore, new fluid is started to perform alternate heat exchange by detecting the liquid level change in the left side pipe, the right side pipe and the central pipe, and the heat exchange effect and the descaling effect are improved.

Fourthly, automatically adjusting vibration based on speed

Preferably, a speed sensing element is arranged inside the free end of the tube bundle and used for detecting the flow rate of the fluid in the free end of the tube bundle, the speed sensing element is in data connection with the controller, and the controller controls the opening and closing of the first valve 24, the second valve 25 and the third valve 26 according to the detected speed of the fluid, so as to control whether the first fluid, the third fluid and the second fluid exchange heat or not.

The speed detected by the speed sensing element can basically reach saturation of the evaporation of the internal fluid under the condition of meeting a certain speed (such as the highest upper limit), so that stable flow is formed, and the speed of the internal fluid basically does not change greatly. And new fluid is started to perform alternate heat exchange by detecting the speed change, so that the heat exchange effect and the descaling effect are improved.

Preferably, the speed sensing element is disposed at the free end. Through setting up at the free end, can perceive the speed change of free end to realize better control and regulation.

Preferably, the average temperatures of the first fluid, the second fluid and the third fluid are the same, the flow rate per unit time of the first fluid per unit time is equal to the flow rate per unit time of the third fluid, and the flow rate per unit time of the first fluid per unit time is 0.5 times the flow rate per unit time of the second fluid. The average temperature is an average of the fluid inlet temperature and the fluid outlet temperature.

Preferably, the first fluid, the second fluid and the third fluid are the same fluid.

As shown preferably in fig. 4, the first fluid, the second fluid and the third fluid have a common inlet header 27 and outlet header 28. Fluid enters the inlet header, enters the first heat exchange tube and the second heat exchange tube through the inlet header for heat exchange, and then flows out through the outlet header.

As shown preferably in fig. 5, the first, second and third fluids have respective inlet and outlet headers 29-30 and 31-32, respectively. The fluid enters the respective inlet headers, then enters the first heat exchange tubes, the second heat exchange tubes and the third heat exchange tubes through the inlet headers for heat exchange, and then flows out through the respective outlet headers.

Preferably, the bottom parts of the right channel box and the left channel box are provided with return pipes communicated with the central pipe, so that the fluid condensed in the first channel box and the second channel box can rapidly flow.

Preferably, the pipe diameter of the right side pipe is equal to that of the left side pipe. The pipe diameters of the right side pipe and the left side pipe are equal, so that the fluid can be ensured to be subjected to phase change in the first box body and keep the same transmission speed with the left pipe box.

Through the alternate heating of the three fluids in the period, the periodic frequent vibration of the elastic coil can be realized, thereby realizing good descaling and heating effects and ensuring that the heating power is basically the same in time.

Preferably, the annular pipes of the left pipe group are distributed by taking the axis of the left pipe as the center of a circle, and the annular pipes of the right pipe group are distributed by taking the axis of the right pipe as the center of a circle. The left side pipe and the right side pipe are arranged as circle centers, so that the distribution of the annular pipes can be better ensured, and the vibration and the heating are uniform.

Preferably, the tube group is plural.

Preferably, the center pipe 8, the left pipe 21, and the right pipe 22 are provided along the height direction.

Preferably, the left tube group 21 and the right tube group 22 are staggered in the height direction, as shown in fig. 3. Through the staggered distribution, can make to vibrate heat transfer and scale removal on the not co-altitude for the vibration is more even, strengthens heat transfer and scale removal effect.

Preferably, the tube group 2 is provided in plural (for example, the same side (left side or right side)) in the height direction of the center tube 8, and the tube diameter of the tube group 2 (for example, the same side (left side or right side)) becomes larger in the shell-side gas flow direction.

Preferably, the pipe diameter of the annular pipe of the pipe group (for example, the same side (left side or right side)) is increased continuously along the gas flowing direction in the shell side.

The pipe diameter range through the heat exchange tube increases, can guarantee that shell side gas outlet position fully carries out the heat transfer, forms the heat transfer effect like the adverse current, further strengthens the heat transfer effect moreover for whole vibration effect is even, and the heat transfer effect increases, further improves heat transfer effect and scale removal effect. Experiments show that better heat exchange effect and descaling effect can be achieved by adopting the structural design.

Preferably, the tube group on the same side (left side or right side) is provided in plural along the height direction of the center tube 8, and the distance between the adjacent tube groups on the same side (left side or right side) becomes smaller along the gas flow direction in the shell side.

Preferably, the spacing between banks on the same side (left or right) in the shell side in the direction of gas flow increases in a decreasing manner.

The interval amplitude through the heat exchange tube increases, can guarantee that shell side gas outlet position fully carries out the heat transfer, forms the heat transfer effect like the adverse current, further strengthens the heat transfer effect moreover for the whole vibration effect is even, and the heat transfer effect increases, further improves heat transfer effect and scale removal effect. Experiments show that better heat exchange effect and descaling effect can be achieved by adopting the structural design.

In tests it was found that the pipe diameters, distances and pipe diameters of the left side pipe 21, the right side pipe 22, the central pipe 8 and the pipe diameters of the ring pipes can have an influence on the heat exchange efficiency and the uniformity. If the distance between the collector is too big, then heat exchange efficiency is too poor, and the distance between the ring shape pipe is too little, then the ring shape pipe distributes too closely, also can influence heat exchange efficiency, and the pipe diameter size of collector and heat exchange tube influences the volume of the liquid or the steam that holds, then can exert an influence to the vibration of free end to influence the heat transfer. Therefore, the pipe diameters and distances of the left pipe 21, the right pipe 22, the central pipe 8 and the pipe diameters of the ring pipes have a certain relationship.

The invention provides an optimal size relation summarized by numerical simulation and test data of a plurality of heat pipes with different sizes. Starting from the maximum heat exchange amount in the heat exchange effect, nearly 200 forms are calculated. The dimensional relationship is as follows:

the distance between the center of the central tube 8 and the center of the left tube 21 is equal to the distance between the center of the central tube 8 and the center of the right tube 21, L, the distance between the center of the left tube 21 and the center of the right tube 21 is M, the tube diameters of the left tube 21, the central tube 8 and the right tube 22 are R, the radius of the axis of the innermost annular tube in the annular tubes is R1, and the radius of the axis of the outermost annular tube is R2, so that the following requirements are met:

R1/R2 ═ a × Ln (R/M) + b; wherein a, b are parameters, Ln is a logarithmic function, wherein 0.5785 < a < 0.5805, 1.6615 < b < 1.6625; preferably, a is 0.579 and b is 1.6621.

Preferably, 35 < R < 61 mm; l is more than 114 and less than 190 mm; 69 < R1 < 121mm, 119 < R2 < 201 mm. M ═ 2L.

Preferably, the number of annular tubes of the tube set is 3-5, preferably 3 or 4.

Preferably, 0.56 < R1/R2 < 0.61; R/L is more than 0.3 and less than 0.33.

Preferably, 0.583 < R1/R2 < 0.615; R/L is more than 0.315 and less than 0.332.

Preferably, the radius of the annular tube is preferably 10-40 mm; preferably 15 to 35mm, more preferably 20 to 30 mm.

Preferably, the centers of the left tube 21, the right tube 22 and the center tube 8 are on a straight line.

Preferably, the arc between the ends of the free ends 3, 4 around the centre axis of the left tube is 95-130 degrees, preferably 120 degrees. The same applies to the curvature of the free ends 5, 6 and the free ends 3, 4. Through the design of the preferable included angle, the vibration of the free end is optimal, and therefore the heating efficiency is optimal.

Preferably, the box body has a circular cross section, and is provided with a plurality of heat exchange components, wherein one heat exchange component is arranged at the center of the circular cross section (the center pipe is positioned at the center of the circle) and the other heat exchange components are distributed around the center of the circular cross section.

Preferably, the tube bundle of the tube bank 1 is an elastic tube bundle.

The heat exchange coefficient can be further improved by arranging the tube bundle of the tube group 1 with an elastic tube bundle.

Further preferably, the heat source is an electric heating rod.

The number of the pipe groups 1 is multiple, and the plurality of pipe groups 1 are in a parallel structure.

The heat exchanger shown in fig. 6 has a circular cross-sectional housing in which the plurality of heat exchange members are disposed. Preferably, the number of the heat exchange components is three, the center of the central tube of the heat exchange component is located at the midpoint of an inscribed regular triangle with a circular cross section, the connecting lines of the centers of the central tubes form a regular triangle, and the extension lines of the connecting lines of the centers of the left tube, the right tube and the central tube form a regular triangle. Through such setting, can make and to fully reach vibrations and heat transfer purpose in can making the heater, improve the heat transfer effect.

Learn through numerical simulation and experiment, heat transfer part's size and circular cross-section's diameter have very big influence to the heat transfer effect, heat transfer part size too big can lead to adjacent interval too little, the space that the centre formed is too big, middle heating effect is not good, the heating is inhomogeneous, on the same way, heat transfer part size undersize can lead to adjacent interval too big, leads to whole heating effect not good. Therefore, the invention obtains the optimal size relation through a large amount of numerical simulation and experimental research.

The distance between the centers of the left side pipe and the right side pipe is L1, the side length of the inscribed regular triangle is L2, the radius of the axis of the innermost annular pipe in the annular pipes is R1, and the radius of the axis of the outermost annular pipe is R2, so that the following requirements are met:

10*(L1/L2)＝d*(10*R1/R2)-e*(10*R1/R2)²-f; wherein d, e, f are parameters,

44.102＜d＜44.110，3.715＜e＜3.782，127.385＜f＜127.395；

more preferably, d is 44.107, e is 3.718, f is 127.39;

of these, 720 < L2 < 1130mm is preferred. Preferably 0.58 < R1/R2 < 0.62.

Further preferably 0.30 < L1/L2 < 0.4.

Through the layout of the three heat exchange component structure optimization, the whole heat exchange effect can reach the best heat exchange effect.

Preferably, the period is 50 to 300 minutes, preferably 50 to 80 minutes.

Preferably, the axes of the left tube, the right tube and the middle tube are connected in a straight line or on a plane.

Preferably, the pipe diameters of the left side pipe and the right side pipe are smaller than the pipe diameter of the middle pipe. The pipe diameter of the middle pipe is preferably 1.4-1.5 times of the pipe diameter of the left side pipe and the right side pipe. Through the pipe diameter setting of left side pipe, right side pipe and intermediate pipe, can guarantee that the fluid carries out the phase transition and keeps the same or close transmission speed at left side pipe, right side pipe and intermediate pipe to guarantee the homogeneity of conducting heat.

Preferably, the connection position of the coil pipe at the left channel box is lower than the connection position of the middle channel box and the coil pipe. This ensures that steam can rapidly enter the intermediate header. Similarly, the connecting position of the coil pipe at the right channel box is lower than the connecting position of the middle channel box and the coil pipe

Although the present invention has been described with reference to the preferred embodiments, it is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method for controlling the flow rate of a four-fluid heat exchanger with three valves to be opened and closed comprises a shell, a heat exchange part, a shell side inlet connecting pipe and a shell side outlet connecting pipe; the heat exchange component is arranged in the shell and fixedly connected to the front tube plate and the rear tube plate; the shell pass inlet connecting pipe and the shell pass outlet connecting pipe are both arranged on the shell; the shell pass fluid enters from a shell pass inlet connecting pipe, exchanges heat through the heat exchange part and exits from a shell pass outlet connecting pipe;

2. A shell and tube heat exchanger according to claim 1, wherein when the first and third fluids exchange heat and the second fluid does not exchange heat, if the speed sensed by the speed sensing element is higher than a certain value, the controller controls the first and third valves to be closed and the second valve to be opened, so that the first and third fluids stop exchanging heat and the second fluid exchanges heat; when the first fluid and the third fluid stop exchanging heat and the second fluid exchanges heat, if the speed detected by the speed sensing element is higher than a certain value, the controller controls the first valve and the third valve to be opened and the second valve to be closed, so that the first fluid and the third fluid exchange heat and the second fluid stops exchanging heat.

3. A shell and tube heat exchanger according to claim 1, wherein the heat exchanging member comprises a center tube, a left tube, a right tube, and tube groups, the tube groups comprising a left tube group and a right tube group, the left tube group being in communication with the left tube and the center tube, the right tube group being in communication with the right tube and the center tube, so that the center tube, the left tube, the right tube, and the tube groups form a closed circulation of the heating fluid, the left tube and/or the center tube and/or the right tube being filled with the phase change fluid, each tube group comprising a plurality of annular tubes in a circular arc shape, ends of adjacent annular tubes being in communication, so that the plurality of annular tubes form a serial structure, and so that the ends of the annular tubes form free ends of the annular tubes; the central tube comprises a first tube orifice and a second tube orifice, the first tube orifice is connected with the inlet of the left tube group, the second tube orifice is connected with the inlet of the right tube group, the outlet of the left tube group is connected with the left tube, and the outlet of the right tube group is connected with the right tube; the first pipe orifice and the second pipe orifice are arranged on the same side of the central pipe; the position of the right tube group is the position of the left tube group after rotating 180 degrees along the axis of the central tube;

4. A shell and tube heat exchanger as claimed in claim 1, wherein the shell-side fluid is a cold source and the first, second and third fluids are hot sources.

5. A shell-and-tube heat exchanger is characterized by comprising a plurality of circular arc-shaped annular tubes, wherein the end parts of the adjacent annular tubes are communicated, so that the annular tubes form a series structure.