CN112648862B

CN112648862B - Three-heat-source shell-and-tube heat exchanger capable of switching heat sources according to temperature

Info

Publication number: CN112648862B
Application number: CN202010060624.8A
Authority: CN
Inventors: 季万祥; 魏民; 柏超; 王一龙; 赵雯涵
Original assignee: Shandong University; Shandong Jianzhu University
Current assignee: Shandong University; Shandong Jianzhu University
Priority date: 2020-01-19
Filing date: 2020-01-19
Publication date: 2022-05-27
Anticipated expiration: 2040-01-19
Also published as: CN112648862A

Abstract

The invention provides a three-heat-source shell-and-tube heat exchanger capable of switching heat sources according to temperature. The invention provides a method for starting a new heat source to perform alternating heat exchange by detecting the temperature change in the left side pipe, the right side pipe and the central pipe, thereby increasing the heat exchange effect and the descaling effect.

Description

Three-heat-source shell-and-tube heat exchanger capable of switching heat sources according to temperature

Technical Field

The invention relates to a shell-and-tube heat exchanger, in particular to a shell-and-tube heat exchanger for intermittent vibration descaling.

Background

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 in the 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, a physical cleaning mode is adopted, and 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 no longer flows 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.

Current shell and tube heat exchangers include dual headers, one for evaporation and one for condensation, to form a vibrating, descaling 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 three-heat-source shell-and-tube heat exchanger 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 lower. The present application therefore makes further improvements to the foregoing studies.

Disclosure of Invention

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

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

a three-heat-source shell-and-tube heat exchanger capable of switching heat sources according to temperature comprises a shell, wherein tube plates are respectively arranged at two ends of the shell, a heat exchange component is arranged in the shell, the heat exchange component comprises a central pipe, a left pipe, a right pipe and a pipe group, the tube group comprises 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, the central tube, the left tube, the central tube and the right tube are respectively provided with a first heat source, a second heat source and a third heat source, each tube group comprises a plurality of circular arc-shaped annular tubes, the end parts of the adjacent annular tubes are communicated, so that the plurality of 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, and the left pipe group and the right pipe group are in mirror symmetry along the plane of the axis of the central pipe; 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 device is characterized in that a first temperature sensor, a second temperature sensor and a third temperature sensor are respectively arranged in the left side pipe, the central pipe and the right side pipe and used for detecting the temperature in the left side pipe, the central pipe and the right side pipe, the first temperature sensor, the second temperature sensor and the third temperature sensor are in data connection with a controller, and the controller controls whether the first heat source, the third heat source and the second heat source are heated or not according to the detected temperatures of the left side pipe, the right side pipe and the central pipe.

Preferably, when the first and third heat sources heat and the second heat source does not 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 heat sources to stop heating and the second heat source to heat; when the first heat source and the third heat source stop heating and the second heat source heats, and when the temperature detected by the second temperature sensing element is higher than a certain value, the controller controls the first heat source and the third heat source to heat and the second heat source stops heating.

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.

Preferably, the heat source is an electric heater.

The invention has the following advantages:

1. according to the invention, the temperature detected by the temperature sensing element can be satisfied under the condition that a certain temperature is met, the evaporation of the fluid in the left side pipe, the right side pipe or the central pipe is basically saturated, and the volume of the internal fluid is basically not changed greatly. Therefore, new heat sources are started to perform alternate heat exchange by detecting the temperature changes in the left side pipe, the right side pipe and the central pipe, and the heat exchange effect and the descaling effect are improved.

2. The 3 heat sources of the invention heat alternately in a period, and can realize frequent vibration of the elastic coil, thereby realizing good descaling and heating effects and ensuring that the heating power is basically the same in time.

3. The invention increases the heating power of the coil pipe periodically and continuously and reduces the heating power, so that the heated fluid can generate the volume which is continuously in a changing state after being heated, and the free end of the coil pipe is induced to generate vibration, thereby strengthening heat transfer.

4. The heating efficiency can be further improved by arranging the pipe diameters and the intervals of the pipe groups in the length direction.

5. The invention optimizes the optimal relationship of the parameters of the shell-and-tube heat exchanger through a large amount of experiments and numerical simulation, thereby realizing the optimal heating efficiency.

6. The invention designs a triangular layout diagram of a multi-heat exchange component with a novel structure, optimizes the structural parameters of the layout, and can further improve the heating efficiency through the layout.

Description of the drawings:

fig. 1 is a schematic view of a housing structure.

Fig. 2 is a top view of a heat exchange member of the present invention.

Fig. 3 is a front view of the heat exchange member of the present invention.

Fig. 4 is a front view of another embodiment of a heat exchange member of the present invention.

Fig. 5 is a dimensional structure schematic diagram of the heat exchange part of the invention.

FIG. 6 is a schematic view of the arrangement of the heat exchange member of the present invention in a circular cross-section heater.

In the figure: 1. the heat exchanger comprises a tube group, a left tube group 11, a

right tube group

12, 21, a left tube 22, a right tube 3, a free end 4, a free end 5, a free end 6, a free end 7, a ring tube 8, a central tube 91-93, a heat source 10, a first tube orifice 13, a second tube orifice 13, a left return tube 14, a right return tube 15, a front tube plate 16, a support 17, a support 18, a rear tube plate 19, a shell 20, a shell 21, a shell side inlet connecting tube 22, a shell side outlet connecting tube and a heat exchange component 23.

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 horizontal direction. The heat exchanger is arranged in the horizontal direction.

Fig. 2 shows a top view of a heat exchange unit 23, which, as shown in fig. 2, comprises a central tube 8, a left tube 21, a right tube 22 and a tube bank 1, the tube set 1 comprises a left tube set 11 and a right tube set 12, the left tube set 11 being in communication with a left side tube 21 and a central tube 8, the right tube set 12 being in communication with a right side tube 22 and the central tube 8, so that the central tube 8, the left side tube 21, the right side tube 22 and the tube group 1 form a closed circulation of heating fluid, the left side tube 21 and/or the central tube 8 and/or the right side tube 22 are filled with phase-change fluid, the left side tube 21, the central tube 8 and the right side tube 22 are respectively provided with a first heat source 91, a second heat source 92 and a third heat source 93, each tube group 1 comprises a plurality of circular arc-shaped annular tubes 7, the end parts of the adjacent annular tubes 7 are communicated, the plurality of annular tubes 7 form a serial structure, and the end parts of the annular tubes 7 form free ends 3-6 of the annular 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. The left tube group and the right tube group are in mirror symmetry along the plane of the axis of the central tube.

The end portions of both ends of the center tube 8, the left tube 21, and the right tube 22 are disposed in the openings of the front and

rear tube plates

16, 19 for fixation. The first orifice 10 and the second orifice 13 are located on the upper side 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. Both ends of the central tube are preferred.

Preferably, the fluid is a phase-change fluid, a vapor-liquid phase-change fluid, the first heat source 91, the second heat source 92 and the third heat source 93 are in data connection with a controller, and the controller controls the first heat source 91, the second heat source 92 and the third heat source 93 to heat.

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 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 can be 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 3 heat sources are alternately heated in a period, and the periodic frequent vibration of the elastic coil can be realized, so that good descaling and heating effects are realized, and 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 tube 8, the left tube 21, and the right tube 22 are provided along the longitudinal direction.

Preferably, the left tube group 21 and the right tube group 22 are staggered in the longitudinal direction, as shown in fig. 3. Through the staggered distribution, can make to vibrate heat transfer and scale removal on different length for the vibration is more even, strengthens heat transfer and scale removal effect.

Preferably, the tube group 1 is provided in plural (for example, the same side (left side or right side)) along the length direction of the center tube 8, and the tube diameter of the tube group 1 (for example, the same side (left side or right side)) becomes larger along the flow direction of the fluid in the shell side.

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

The pipe diameter range through the heat exchange tube increases, can guarantee that shell side fluid 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 obtained by adopting the structural design.

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

Preferably, the spacing between the tube banks on the same side (left or right) in the direction of fluid flow in the shell side is increased by a decreasing amount.

The interval amplitude through the heat exchange tube increases, can guarantee that shell side fluid 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 obtained 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 22, L, the tube diameter of the left tube 21, the tube diameter of the central tube 8 and the radius of 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/L) + b; where a, b are parameters, Ln is a logarithmic function, where 0.6212< a <0.6216, 1.300< b < 1.301; preferably, a is 0.6214 and b is 1.3005.

Preferably, 35< R <61 mm; 114< L <190 mm; 69< R1<121mm, 119< R2<201 mm.

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

Preferably, 0.55< R1/R2< 0.62; 0.3< R/L < 0.33.

Preferably, 0.583< R1/R2< 0.615; 0.315< R/L < 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 heat exchange component can be used as an immersed heat exchange assembly, immersed in a fluid to heat the fluid, for example, the heat exchange component can be used as an air radiator heating assembly, and can also be used as a water heater heating assembly.

The heating power of the first, second and third heat sources is preferably 1000-.

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 arranged 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 each heat exchange component is located at the midpoint of an inscribed regular triangle of the circular cross section, the connecting lines of the centers of the central tubes form the regular triangle, one heat exchange component is arranged at the upper part of each central tube, two heat exchange components are arranged at the lower part of each central tube, and the connecting lines formed by the left side tube, the right side tube and the centers of the central tubes of the heat exchange components are of a parallel structure. Through such setting, can be so that the interior fluid of heater fully reaches vibrations and heat transfer purpose, 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；

further preferably, d =44.107, e =3.718, f = 127.39;

with 720< L2<1130mm preferred. Preferably 0.58< R1/R2< 0.62.

Further preferred is 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.

It has been found in research and practice that a constant and stable heat source results in a fluid-forming stability of the internal heat exchange components, i.e. no or little fluid flow, or a stable flow, which results in a strongly reduced vibration performance of the line set 1, thereby affecting the efficiency of the descaling and heating of the line set 1. Therefore, the heat pipe described above needs to be improved 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 result in 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-adjusting vibration based on pressure

Preferably, the left tube 21, the center tube 8 and the right tube 22 are respectively provided with a first pressure sensor, a second pressure sensor and a third pressure sensor for detecting the pressures in the left tube, the center 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 whether the first heat source 91, the third heat source 93 and the second heat source 92 are heated or not according to the detected pressures in the left tube, the right tube and the center tube.

Preferably, when the first and third heat sources heat and the second heat source does not 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 heat sources to stop heating and the second heat source to heat; when the first heat source and the third heat source stop heating and the second heat source heats, and when the pressure detected by the second pressure sensing element is higher than a certain value, the controller controls the first heat source and the third heat source to heat and the second heat source stops heating.

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 heat sources are 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, the left tube 21, the center tube 8 and the right tube 22 are respectively provided with a first temperature sensor, a second temperature sensor and a third temperature sensor for detecting the temperature inside the left tube, the center 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 whether the first heat source 91, the third heat source 93 and the second heat source 92 are heated or not according to the detected temperatures of the left tube, the right tube and the center tube.

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 heat sources are started to perform alternate heat exchange by detecting the temperature changes in the left side pipe, the right side pipe and the central pipe, and the heat exchange effect and the descaling effect are improved.

Third, vibration is automatically adjusted 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 whether the first heat source 91, the third heat source 93 and the second heat source 92 are heated or not according to the detected liquid levels of the left side pipe, the right side pipe and the central pipe.

Preferably, when the first and third heat sources heat and the second heat source does not 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 or third liquid level sensing element is lower than a certain value, the controller controls the first and third heat sources to stop heating and the second heat source to heat; when the first heat source and the third heat source stop heating and the second heat source heats, and when the liquid level detected by the second liquid level sensing element is lower than a certain value, the controller controls the first heat source and the third heat source to heat, and the second heat source stops heating.

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, a new heat source 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, vibration is automatically adjusted based on speed

Preferably, a speed sensing element is arranged inside the free end of the tube bundle for detecting the flow speed 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 whether the first and

third heat sources

91 and 93 and the second electric heater 92 are heated or not according to the detected speed of the fluid.

Preferably, when the first and third heat sources heat and the second heat source does not heat, if the speed detected by the speed sensor is higher than a certain value, the controller controls the first and third heat sources to stop heating and the second heat source to heat; when the first and third heat sources stop heating and the second heat source heats, if the speed detected by the speed sensing element is higher than a certain value, the controller controls the first and third heat sources to heat and the second heat source stops heating.

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 a new heat source 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 heat source is an electric heater.

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 pass up into the central tube. 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 three-heat-source shell-and-tube heat exchanger for switching heat sources according to temperature comprises a shell, wherein tube plates are respectively arranged at two ends of the shell, a heat exchange component is arranged in the shell, the heat exchange component comprises a central tube, a left tube, a right tube and a tube group, the tube group comprises 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, the central tube, the left tube, the central tube and the right tube are respectively provided with a first heat source, a second heat source and a third heat source, each tube group comprises a plurality of circular arc-shaped annular tubes, the end parts of the adjacent annular tubes are communicated, so that the plurality of 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, and the left pipe group and the right pipe group are in mirror symmetry along the plane of the axis of the central pipe; 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 device is characterized in that a first temperature sensor, a second temperature sensor and a third temperature sensor are respectively arranged in the left side pipe, the central pipe and the right side pipe and used for detecting the temperature in the left side pipe, the central pipe and the right side pipe, the first temperature sensor, the second temperature sensor and the third temperature sensor are in data connection with a controller, and the controller controls whether the first heat source, the third heat source and the second heat source are heated or not according to the detected temperatures of the left side pipe, the right side pipe and the central pipe.

2. The heat exchanger as claimed in claim 1, wherein when the first and third heat sources perform heating and the second heat source does not perform heating, the controller controls the first and third heat sources to stop heating and the second heat source to perform heating when the temperature sensed by the first or third temperature sensing element is higher than a certain value or the average value of the temperatures sensed by the first and third temperature sensing elements is higher than a certain value; when the first heat source and the third heat source stop heating and the second heat source heats, and when the temperature detected by the second temperature sensing element is higher than a certain value, the controller controls the first heat source and the third heat source to heat and the second heat source stops heating.

3. The heat exchanger of claim 1, wherein the annular tubes of the left tube set are centered on the axis of the left tube and the annular tubes of the right tube set are centered on the axis of the right tube.