CN115014099B - A shell-and-tube heat exchanger with periodic heating - Google Patents

Abstract

The invention provides a tube-shell heat exchanger for periodically changing heating, which comprises a shell, wherein tube plates are respectively arranged at two ends of the shell, heat exchange components are arranged in the shell, a first heat source, a second heat source and a third heat source are respectively arranged as a plurality of electric heating components, each electric heating component is independently controlled, and the starting quantity of the electric heating components is periodically changed along with the change of time. By the time-variable heating, the fluid can be evaporated and expanded in the elastic tube bundle frequently, so that the heating efficiency and the descaling operation can be further realized.

Description

A shell-and-tube heat exchanger with periodic heating

technical field

The invention relates to a shell-and-tube heat exchanger, in particular to a shell-and-tube heat exchanger with periodic heating.

Background technique

Shell-and-tube heat exchangers are widely used in chemical industry, petroleum, refrigeration, nuclear energy and power industries. Due to the worldwide energy crisis, in order to reduce energy consumption, the demand for heat exchangers in industrial production is also increasing. The quality requirements for heat exchangers are also getting higher and higher. In recent decades, although compact heat exchangers (plate, plate-fin, press-welded plate heat exchangers, etc.), heat pipe heat exchangers, direct contact heat exchangers, etc. have been developed rapidly, but due to the The heat exchanger has a high degree of reliability and wide adaptability, and it still occupies a dominant position in output and consumption. According to relevant statistics, the current consumption of shell-and-tube heat exchangers in industrial installations still accounts for 70% of the total heat exchanger consumption. %about.

After fouling of the shell-and-tube heat exchanger, conventional steam cleaning, backwashing and other methods are used to clean the heat exchanger. Production practice has proved that the effect is not very good. Only the head of the heat exchanger can be disassembled, and the method of physical cleaning is adopted, but the operation is complicated, time-consuming, and the investment in manpower and material resources is large, which brings great harm to continuous industrial production. difficulty.

The use of fluid-induced vibration of heat transfer elements to achieve enhanced heat transfer is a form of passive enhanced heat transfer, which can transform the strict prevention of fluid vibration induction in the heat exchanger into the effective use of vibration, so that the transmission elements can operate at low flow rates The convective heat transfer coefficient is greatly improved, and the vibration is used to suppress the dirt on the surface of the heat transfer element, reduce the thermal resistance of the dirt, and realize the compound enhanced heat transfer.

In the application, it is found that continuous heating will lead to the formation of stability of the internal fluid, that is, the fluid is not flowing or has little fluidity, or the flow is stable, resulting in a greatly weakened vibration performance of the heat exchange tube, thus affecting the descaling and heating of the heat exchange tube s efficiency.

The current shell-and-tube heat exchanger includes double headers, one header for evaporation and one header for condensation, thus forming a vibrating descaling heat pipe. Thereby improving the heat exchange efficiency of the heat pipe and reducing fouling. However, the heat transfer uniformity of the above-mentioned heat pipe is not enough, condensation is only performed on one side, and the heat transfer amount is also small, so it needs to be improved to develop a heat pipe system with a new structure. Therefore need to improve above-mentioned heat exchanger.

Contents of the invention

The invention aims at the deficiency of the shell-and-tube heat exchanger in the prior art, and provides a shell-and-tube heat exchanger with a new structure for electric heating. The shell-and-tube heat exchanger can realize periodic and frequent vibrations of the heat exchange tubes, thereby improving the heating efficiency, thereby achieving good descaling and heating effects.

To achieve the above object, the present invention adopts the following technical solutions:

A shell-and-tube heat exchanger with periodic heating, comprising a shell, tube sheets are respectively arranged at both ends of the shell, heat exchange components are set in the shell, and the first heat source, the second heat source, and the third heat source are respectively A plurality of electric heating components are set, each electric heating component is independently controlled, and as time changes, the number of activated electric heating components changes periodically.

As an option, the first heat source, the second heat source, and the third heat source are respectively set as n electric heating components, and one cycle is T, then in the half cycle of 0-T/2, when T=0, the first heat source, All the n electric heating components of the third heat source are turned off, and all the n electric heating components of the second heat source are turned on;

Then every T/2n time, the first heat source and the third heat source start an electric heating component respectively, and the second heat source turns off an electric heating component, until T/2 time the first heat source and the third heat source are all started, and the second heat source All off.

As an option, in the half cycle of T/2-T, every T/2n time, the second heat source starts an electric heating element, and at the same time, the first heat source and the third heat source respectively turn off an electric heating element until the cycle T After the end, all the second heat sources are started, and the first heat source and the third heat source are all turned off.

Alternatively, the heating power of each electric heating component in the first heat source and the third heat source is the same. The power of each electric heating component of the second heat source is twice the power of the electric heating components of the first and third heat sources.

A shell-and-tube heat exchanger, including a shell, tube plates are arranged at both ends of the shell, and heat exchange components are arranged in the shell, and the heat exchange components include a central tube, a left tube, a right tube and a tube group , the tube group includes a left tube group and a right tube group, the left tube group communicates with the left tube and the central tube, and the right tube group communicates with the right tube and the central tube, so that the central tube, the left tube, the right The side pipe and the pipe group form a closed circulation of heating fluid, the left pipe and/or the central pipe and/or the right pipe are filled with phase change fluid, and the left pipe, the central pipe, and the right pipe are respectively provided with a first heat source, a second heat source and The third heat source, each tube group includes a plurality of arc-shaped annular tubes, the ends of adjacent annular tubes are connected, so that the plurality of annular tubes form a series structure, and the ends of the annular tubes form the free ends of the annular tubes; the center The tube includes a first nozzle and a second nozzle, the first nozzle is connected to the inlet of the left tube group, the second nozzle is connected to the inlet of the right tube group, the outlet of the left tube group is connected to the left pipe, and the outlet of the right tube group is connected to Right pipe; the first nozzle and the second nozzle are arranged on the same side of the central pipe, and the left pipe group and the right pipe group are mirror-symmetrical along the plane where the axis of the central pipe is located; the left pipe and the central pipe are A left return pipe is arranged between the tubes, and a right return pipe is arranged between the right side pipe and the central pipe; the controller controls whether the first heat source, the second heat source and the third heat source are heated.

Preferably, the annular pipes of the left pipe group are distributed with the axis of the left pipe as the center of the circle, and the annular pipes of the right pipe group are distributed with the axis of the right pipe as the center of the circle.

Preferably, the heat source is an electric heater.

The present invention has the following advantages:

1. In the present invention, by improving the prior art, the pipe box and the coil pipe are respectively arranged as two left and right distributions, and a heat source is arranged inside each pipe box, and each heat source can be independently heated to become an evaporation part, thereby Enhanced heat transfer, so that the coils distributed on the left and right sides can perform vibration heat exchange and descaling, thereby expanding the area of heat exchange vibration, the more uniform the vibration, the more uniform the heat exchange effect, increasing the heat exchange area, and strengthening the heat exchange area. Thermal and descaling effect.

2. The three heat sources of the steam generator of the present invention are heated alternately within a cycle, which can realize the periodic and frequent vibration of the elastic coil, thereby achieving good descaling and heating effects, and ensuring that the heating power is basically the same in time .

3. In the present invention, the heating power of the coil is increased and decreased periodically, so that the volume of the heating fluid is constantly changing after being heated, and the free end of the coil is induced to vibrate, thereby enhancing heat transfer.

4. In the present invention, the heating efficiency can be further improved through the setting of the pipe group pipe diameter and spacing distribution in the length direction.

5. The present invention optimizes the best relationship of the parameters of the shell-and-tube heat exchanger through a large number of experiments and numerical simulations, thereby realizing the best heating efficiency.

6. The present invention designs a triangular layout diagram of a new structure with multiple heat exchange components, and optimizes the structural parameters of the layout, through which the heating efficiency can be further improved.

Description of drawings

Figure 1 is a schematic diagram of the shell structure.

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

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

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

Fig. 5 is a schematic diagram of the size and structure of the heat exchange component of the present invention.

Fig. 6 is a schematic layout diagram of the heat exchanging components of the present invention in a circular section heater.

Detailed ways

A shell-and-tube heat exchanger, as shown in Figure 1, the shell-and-tube heat exchanger includes a shell 20, a heat exchange component 23, a shell side inlet connection 21 and a shell side outlet connection 22; the heat exchange The components 23 are arranged in the housing 20, and the heat exchange components are fixedly connected to the front tube sheet 16 and the rear tube sheet 19; the shell-side inlet connection 21 and the shell-side outlet connection 22 are both arranged on the casing 20; the fluid flows from The shell-side inlet connecting pipe 21 enters, passes through heat exchange components for heat exchange, and exits through the shell-side outlet connecting pipe 22 .

Preferably, the heat exchange component extends along the horizontal direction. The heat exchangers are arranged horizontally.

Figure 2 shows a top view of the heat exchange component 23, as shown in Figure 2, the heat exchange component includes a central tube 8, a left tube 21, a right tube 22 and a tube group 1, and the tube group 1 includes a left tube group 11 and the right pipe group 12, the left pipe group 11 communicates with the left pipe 21 and the central pipe 8, and the right pipe group 12 communicates with the right pipe 22 and the central pipe 8, so that the central pipe 8, the left pipe 21, The right pipe 22 and the pipe group 1 form a closed loop of heating fluid, the left pipe 21 and/or the central pipe 8 and/or the right pipe 22 are filled with phase change fluid, the left pipe 21, the central pipe 8, and the right pipe 22 A first heat source 91, a second heat source 92, and a third heat source 93 are respectively provided. Each tube group 1 includes a plurality of arc-shaped annular pipes 7, and the ends of adjacent annular pipes 7 are connected to form a plurality of annular pipes 7. Series structure, and make the end of annular pipe 7 form annular pipe free end 3-6; Center pipe comprises first nozzle 10 and second nozzle 13, and first nozzle 10 connects the inlet of left pipe group 11, the second Nozzle 13 connects the inlet of right pipe group 12, the outlet of left pipe group 11 connects left side pipe 21, and the outlet of right pipe group 12 connects right side pipe 22; Described first nozzle 10 and second nozzle 13 are arranged on The same side of the central tube 8. The left tube group and the right tube group are mirror-symmetrical along the plane where the axis of the central tube is located.

The ends of the two ends of the central tube 8, the left side tube 21 and the right side tube 22 are arranged in the openings of the front and rear tube plates 16, 19 for fixing. The first nozzle 10 and the second nozzle 13 are located on the upper side of the central tube 8 .

Preferably, a left return pipe 14 is provided between the left pipe 21 and the central pipe 8 , and a right return pipe 15 is provided 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.

As preferably, the fluid is a phase change fluid, a vapor-liquid phase change fluid, and the first heat source 91, the second heat source 92 and the third heat source 93 are connected to the controller for data, and the controller controls the first heat source 91, The second heat source 92 and the third heat source 93 perform heating.

The fluid is heated and evaporated in the central tube 8, and flows along the annular tube bundle to the left and right headers 21, 22. After being heated, the fluid will expand in volume to form steam, and the volume of steam is much larger than that of water, so the formed The steam will flow in a rapid impulsive manner within the coil. Because of the volume expansion and the flow of steam, the free end of the annular tube can be induced to vibrate, and the free end of the heat exchange tube transmits the vibration to the surrounding heat exchange fluid during the vibration process, and the fluids will also disturb each other, so that the surrounding The heat exchange fluid forms turbulent flow and destroys the boundary layer, thereby achieving the purpose of enhancing heat transfer. After the fluid condenses and releases heat in the left and right side tubes, it returns to the central tube through the return tube. On the contrary, the fluid can also be heated in the left and right side tubes, and then enter the center tube to condense and return to the left and right side tubes through the return tube for circulation.

In the present invention, by improving the existing technology, the condensation header and the tube group are arranged as two distributed on the left and right, so that the tube groups distributed on the left and right sides can perform vibration heat exchange and descaling, thereby expanding the area of heat exchange vibration , the more uniform the vibration can be, the more uniform the heat transfer effect, increase the heat transfer area, and strengthen the heat transfer and descaling effect.

The three heat sources of the inventive steam generator are heated alternately within a cycle, which can realize the periodic and frequent vibration of the elastic coil, thereby achieving good descaling and heating effects, and ensuring that the heating power is basically the same over time.

Preferably, the annular pipes of the left pipe group are distributed with the axis of the left pipe as the center of the circle, and the annular pipes of the right pipe group are distributed with the axis of the right pipe as the center of the circle. By setting the left and right side tubes as the center of the circle, the distribution of the annular tubes can be better ensured, so that the vibration and heating are even.

Preferably, there are multiple tube groups.

Preferably, the central pipe 8 , the left pipe 21 and the right pipe 22 are arranged along the length direction.

Preferably, the left tube group 21 and the right tube group 22 are distributed in a staggered manner in the length direction, as shown in FIG. 3 . Through the staggered distribution, vibration heat exchange and descaling can be performed at different lengths, making the vibration more uniform and enhancing the effects of heat exchange and descaling.

As a preference, along the length direction of the central tube 8, multiple tube sets 1 (for example, on the same side (left or right)) are provided, and along the fluid flow direction in the shell side, the tube sets 1 (for example, on the same side (left or right)) diameter is constantly increasing.

Preferably, along the fluid flow direction in the shell side, the diameter of the annular tubes of the tube group (for example, on the same side (left side or right side)) increases continuously.

By increasing the diameter of the heat exchange tube, it is possible to ensure sufficient heat exchange at the outlet of the shell-side fluid, forming a heat exchange effect similar to countercurrent flow, and further enhancing the heat transfer effect, making the overall vibration effect uniform, increasing the heat exchange effect, and further improving Heat exchange effect and descaling effect. It is found through experiments that adopting this structural design can achieve better heat exchange effect and descaling effect.

As a preference, along the length direction of the central pipe 8, the tube groups on the same side (left or right) are arranged in multiples, and along the fluid flow direction in the shell side, the same side (left or right) is adjacent The distance between the tube groups keeps getting smaller.

Preferably, along the direction of fluid flow in the shell side, the distance between tube groups on the same side (left or right) becomes smaller and larger.

By increasing the spacing of the heat exchange tubes, it is possible to ensure sufficient heat exchange at the outlet of the shell-side fluid, forming a heat exchange effect similar to countercurrent flow, and further enhancing the heat transfer effect, making the overall vibration effect uniform, increasing the heat exchange effect, and further improving the heat exchange effect. Thermal effect and descaling effect. It is found through experiments that adopting this structural design can achieve better heat exchange effect and descaling effect.

It is found in the test that the diameters and distances of the left pipe 21 , the right pipe 22 , and the center pipe 8 and the pipe diameter of the annular pipe can affect the heat exchange efficiency and uniformity. If the distance between the headers is too large, the heat exchange efficiency will be too poor. If the distance between the annular tubes is too small, the distribution of the annular tubes will be too dense, which will also affect the heat exchange efficiency. The diameter of the headers and heat exchange tubes will affect The volume of liquid or steam contained will have an impact on the vibration of the free end, thereby affecting heat transfer. Therefore, the pipe diameters and distances of the left pipe 21, the right pipe 22, and the central pipe 8, and the diameter of the annular pipe have a certain relationship.

The present invention summarizes the best size relationship through the numerical simulation of multiple heat pipes with different sizes and test data. Starting from the maximum amount of heat transfer in the heat transfer effect, nearly 200 forms were calculated. The dimensional relationships described are as follows:

The distance between the center of the center pipe 8 and the center of the left pipe 21 is equal to the distance between the center of the center pipe 8 and the center of the right pipe 21, which is L, the diameter of the left pipe 21, the diameter of the center pipe 8 diameter, the radius of the right pipe 22 is R, the radius of the axis of the innermost ring pipe in the ring pipe is R1, and the radius of the axis of the outermost ring pipe is R2, then the following requirements are met:

R1/R2=a*Ln(R/L)+b; Wherein a, b are parameters, Ln is logarithmic function, wherein 0.6212<a<0.6216, 1.300<b<1.301; As preferred, a=0.6214, b= 1.3005.

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

Preferably, the number of annular tubes in the tube group 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 pipe is preferably 10-40mm; preferably 15-35mm, more preferably 20-30mm.

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

Preferably, the arc between the ends of the free ends 3 and 4 with the central axis of the left pipe as the center is 95-130 degrees, preferably 120 degrees. Similarly, the radians of the free ends 5, 6 and the free ends 3, 4 are the same. Through the above-mentioned preferred design of the included angle, the vibration of the free end can be optimized, so that the heating efficiency can be optimized.

Preferably, the heat exchange component can be used as a submerged heat exchange component, immersed in the fluid to heat the fluid, for example, it can be used as an air radiator heating component, or as a water heater heating component.

The heating power of the first, second and third heat sources is preferably 1000-2000W, more preferably 1500W.

Preferably, the box body has a circular cross-section, and a plurality of heat exchange components are arranged, one of which is set at the center of the circular cross-section (the center tube is at the center of the circle) and the other forms heat exchangers distributed around the circular cross-section center. hot parts.

Preferably, the tube bundles of the tube group 1 are elastic tube bundles.

By setting the tube bundles of the tube group 1 as elastic tube bundles, the heat transfer coefficient can be further improved.

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

There are multiple tube groups 1, and the multiple tube groups 1 are in a parallel structure.

The heat exchanger shown in FIG. 6 has a shell with a circular section, and the plurality of heat exchange components are arranged in the circular shell. As a preference, three heat exchange components are provided in the housing, the center of the central tube of the heat exchange component is located at the midpoint of the inscribed equilateral triangle of the circular section, and the connecting line between the centers of the central tubes forms a regular The upper part is a heat exchange part, the lower part is two heat exchange parts, and the connection line formed by the center of the left pipe, right pipe and center pipe of the heat exchange part is a parallel structure. By setting in this way, the fluid in the heater can fully achieve the purpose of vibration and heat exchange, and the heat exchange effect can be improved.

Preferably, the tube bundles of the tube group are elastic tube bundles.

The heat transfer coefficient can be further improved by setting the tube bundles of the tube group as elastic tube bundles.

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

There are multiple tube groups, and the multiple tube groups are in parallel structure.

The heat exchanger shown in the figure has a shell with a circular cross-section, and the plurality of heat exchange components are arranged in the circular shell. As a preference, three heat exchange components are provided in the housing, the center of the central tube of the heat exchange component is located at the midpoint of the inscribed equilateral triangle of the circular section, and the connecting line between the centers of the central tubes forms a regular The upper part is a heat exchange part, the lower part is two heat exchange parts, and the connection line formed by the center of the left pipe, right pipe and center pipe of the heat exchange part is a parallel structure. By setting in this way, the fluid in the heater can fully achieve the purpose of vibration and heat exchange, and the heat exchange effect can be improved.

As a preference, the first heat source, the third heat source, and the second heat source alternately heat periodically as time changes.

Within a cycle time T, the heating power of the first heat source and the third heat source are W1 and W3, and the heating power of the second heat source is W2, and the changing rules of W1, W2 and W3 are as follows:

In the half period of 0-T/2, W1=n, W2=0, W3=n, that is, the heating power of the first heat source and the third heat source remains constant, and the second heat source does not heat;

In the half period of T/2-T, W1=0, W2=Z, W3=0, that is, the first heat source and the third heat source do not heat, and the heating power of the second heat source remains constant.

As an option, within a cycle time T, the heating power of the first heat source and the third heat source are W1 and W3, and the heating power of the second heat source is W2, and the changing rules of W1, W2 and W3 are as follows:

In the half cycle of 0-T/2, W2=Z, W1=0, W3=0, that is, the first and third heat sources are not heated, and the heating power of the second heat source remains constant;

In the half cycle of T/2-T, W2=0, W1=n; W3=n; where n is a constant value, the unit is watts (W), that is, the second heat source does not heat, and the first and third heat sources heat Power remains constant.

Among them, Z and n are constant values, and the unit is watts (W). Preferably, Z=2n.

T is 50-80 minutes, of which 1000W<n<1500W.

The above-mentioned time-varying heating can make the fluid evaporate and expand frequently in the elastic tube bundle, because the continuous periodic change of steam expansion and flow direction destroys the stability of single heating, thereby continuously driving the elastic tube bundle Vibration, which can further achieve heating efficiency and descaling operation.

Compared with the previous application, this heating method not only ensures that the heat exchange component is heated in the whole cycle, but also enables the elastic tube bundle to vibrate frequently, so that the heating efficiency and descaling operation can be further realized.

Preferably, along the length direction of the shell, the heat source is arranged in multiple sections, and each section is independently controlled. As time changes, in half a cycle of 0-T/2, when T=0, the first heat source, the third heat source All sections of the second heat source are all turned off, and all sections of the second heat source are turned on;

Then the first heat source and the third heat source are started sequentially along the direction opposite to the fluid flow direction in the shell side (for example, starting from the right end of Figure 1), until all segments are started, and at the same time, the second heat source starts to be turned off sequentially along the fluid flow direction in the shell side, until all segments are closed;

In the half cycle of T/2-T, the first heat source and the third heat source start to close sequentially along the fluid flow in the shell side, and the second heat source starts to turn on sequentially along the opposite direction of the fluid flow in the shell side until the end of the cycle. All sections of the first heat source and the third heat source are all closed, and all sections of the second heat source are all opened.

That is, assuming that the first heat source, the second heat source, and the third heat source are all n segments respectively, then in a cycle T, when T=0, all segments of the first heat source and the third heat source are all closed, and all segments of the second heat source all open;

Then every T/2n time, the first heat source and the third heat source start a section from the direction opposite to the fluid flow direction in the shell side, and at the same time, the second heat source turns off a section from the fluid flow direction in the shell side until T/2 All sections of the first heat source and the third heat source are activated, and all sections of the second heat source are closed;

Then every T/2n time, the first heat source and the third heat source start from the fluid flow direction in the shell side, and close a section every T/2n time, while the second heat source starts from the opposite direction of the fluid flow direction in the shell side At the beginning, one segment is turned on every T/2n time, until T time all segments of the first heat source and the third heat source are turned off, and all segments of the second heat source are turned on.

As an option, in the half cycle of 0-T/2, when T=0, all sections of the first heat source and the third heat source are all turned on, and all sections of the second heat source are all turned off; then the first heat source and the third heat source Start to close sequentially along the direction of fluid flow in the shell side until all sections are closed, and at the same time turn on the second heat source sequentially along the opposite direction of fluid flow in the shell side until all sections are open;

In the half cycle of T/2-T, the second heat source is turned off sequentially from the upper end, the first heat source and the third heat source are turned on sequentially from the opposite direction of fluid flow in the shell side, until the end of the cycle, all sections of the second heat source All are closed, and all sections of the first and second heat sources and the third heat source are all opened.

That is, assuming that the first heat source, the second heat source, and the third heat source are all n sections respectively, then in a cycle T, when T=0, all sections of the second heat source are all closed, and all sections of the first heat source and the third heat source all open;

Then every T/2n time, the second heat source starts a section from the direction opposite to the fluid flow direction in the shell side, and at the same time, the first heat source and the third heat source turn off a section from the fluid flow direction in the shell side until T/2 All sections of the second heat source are activated, and all sections of the first heat source and the third heat source are turned off;

Then every T/2n time, the second heat source starts from the fluid flow direction in the shell side, and closes a section every T/2n time, while the first heat source and the third heat source start from the opposite direction of the fluid flow direction in the shell side At the beginning, one segment is turned on every T/2n time, until T time all segments of the second heat source are turned off, and all segments of the first heat source and the third heat source are turned on.

Preferably, the heating power of each segment of the first heat source and the third heat source is the same. Each section of the second heat source is twice the heating power of each section of the first and third heat sources. The relationship diagram is shown in Figure 4.

By gradually starting the heat source along the opposite direction of the fluid flow and closing it from the direction of the fluid flow, the heating temperature at the rear end can be increased to form a similar countercurrent effect, further promote the flow of the fluid, and increase the elastic vibration effect. Through the above-mentioned time-varying heating power change, the fluid in the elastic tube bundle can be frequently evaporated, expanded and contracted, thereby continuously driving the vibration of the elastic tube bundle, thereby further realizing heating efficiency and descaling operation.

Preferably, there are multiple first heat sources, and each heat source has a different power, and one or more of them can be combined to form different heating powers; there are multiple second heat sources, and each heat source has a different power. There are multiple third heat sources, and each heat source has a different power, and one or more of them can be combined to form different heating powers

In the period T, T=0, the multiple first heat sources and the multiple third heat sources are all turned off, and the multiple second heat sources are all turned on,

As an option, in the half cycle of 0-T/2, according to the time sequence, the single first heat source is started first, the single first heat source is started independently in the order of increasing heating power, and then the two first heat sources are started, The two first heat sources are started independently in the order of increasing heating power, and then gradually increase the number of first heat sources started, if the number is n, then n first heat sources are started independently in the order of increasing heating power; until finally all The first heat source is activated to ensure that the heating power of the first heat source increases sequentially;

At the same time, the single third heat source is started first, and the single third heat source is started independently in the order of increasing heating power, and then the two third heat sources are started, and the two third heat sources are started independently in the order of increasing heating power, and then gradually increase The number of the third heat sources to start, if the number is n, then the n third heat sources are started independently in the order of increasing heating power; until all the third heat sources are started at last, the heating power of the third heat sources is guaranteed to increase in order;

At the same time, the single second heat source is turned off. The single second heat source is turned off independently in the order of increasing heating power, and then the two second heat sources are turned off. The two second heat sources are turned off independently in the order of increasing heating power, and then gradually increase the second heat source. The number of two heat sources turned off, if the number is n, then the n second heat sources are independently turned off in the order of increasing heating power; until all the second heat sources are turned off at last, the heating power of the second heat sources is guaranteed to decrease in turn.

In the second half cycle of T/2-T, the single first heat source is turned off first, and the single first heat source is turned off independently in the order of increasing heating power, and then the two first heat sources are turned off, and the two first heat sources are turned off according to the heating power Turn off independently in the order of increasing power, and then gradually increase the number of first heat sources that are turned off. If the number is n, then n first heat sources are turned off independently in the order of increasing heating power; until finally all the first heat sources are turned off, ensuring The heating power of the first heat source decreases sequentially.

At the same time, the single third heat source is turned off, the single third heat source is turned off independently in the order of increasing heating power, and then the two third heat sources are turned off, the two third heat sources are turned off independently in the order of increasing heating power, and then gradually increase the third heat source The number of three heat sources closed, if the number is n, then the n third heat sources are independently closed in the order of increasing heating power; until all the third heat sources are closed at last, the heating power of the third heat sources is guaranteed to decrease sequentially.

At the same time, according to the time sequence, the single second heat source is started first, and the single second heat source is started independently in the order of increasing heating power, and then the two second heat sources are started, and the two second heat sources are started independently in the order of increasing heating power , and then gradually increase the number of second heat sources activated, if the number is n, then the n second heat sources are independently activated in the order of increasing heating power; until finally all the second heat sources are activated to ensure the heating of the second heat sources The power increases sequentially.

For example, there are three first heat sources, namely the first heat source V1, the first heat source V2 and the first heat source V3, and the heating powers are respectively W1, W2 and W3, wherein W1<W2<W3, W1+W2>W3; That is, the sum of the heating power of V1 and V2 is greater than the heating power of V3. In the first half cycle, V1, V2, V3 are started sequentially in chronological order, V1 plus V2, V1 plus V3, V2 plus V3, and then V1+V2+V3 , the order of closing in the next half cycle is V1, V2, V3, V1 plus V2, V1 plus V3, V2 plus V3.

There are three third heat sources, namely the third heat source V4, the third heat source V5 and the third heat source V6, and the heating powers are respectively W4, W5 and W6, wherein W4<W5<W6, W4+W5>W6; namely The sum of the heating power of V4 and V5 is greater than the heating power of V6. In the first half cycle, start V4, V5, V6, V4 plus V5, V4 plus V6, V5 plus V6, and then V4+V5+V6. The order of closing in the next half cycle is V4, V5, V6, V4 plus V5, V4 plus V6, V5 plus V6.

There are three second heat sources, which are respectively the second heat source Z1, the second heat source Z2 and the second heat source Z3, and the heating powers are respectively W1, W2 and W3, wherein W1<W2<W3, W1+W2>W3; namely The sum of the heating power of Z1 and Z2 is greater than the heating power of Z3. In the first half cycle, Z1, Z2, Z3 are turned off in order of time, Z1 plus Z2, Z1 plus Z3, Z2 plus Z3, and then Z1+Z2+Z3, The turn-on sequence in the second half cycle is Z1, Z2, Z3, Z1 plus Z2, Z1 plus Z3, Z2 plus Z3.

As an option, in the period T, T=0, all the multiple second heat sources are turned off, all the multiple first heat sources and the third heat sources are all turned on,

In the half cycle of 0-T/2, according to the time sequence, the single second heat source is started first, and the single second heat source is started independently in the order of increasing heating power, and then the two second heat sources are started, and the two second heat sources are started. The heat sources start independently in the order of increasing heating power, and then gradually increase the number of second heat sources starting. If the number is n, n second heat sources start independently in order of increasing heating power; until finally all the second heat sources Start to ensure that the heating power of the first heat source increases sequentially; at the same time, the single first heat source is turned off, and the single first heat source is turned off independently in the order of increasing heating power, and then the two first heat sources are turned off, and the two first heat sources are turned off in accordance with Turn off the heating power independently in the order of increasing heating power, and then gradually increase the number of first heat sources that are turned off. If the number is n, then n first heat sources are turned off independently in the order of increasing heating power; until finally all the second heat sources are turned off, It is ensured that the heating power of the second heat source decreases sequentially. At the same time, the single third heat source is turned off, the single third heat source is turned off independently in the order of increasing heating power, and then the two third heat sources are turned off, the two first heat sources are turned off independently in the order of increasing heating power, and then gradually increase the third heat source The number of three heat sources closed, if the number is n, then the n third heat sources are independently closed in the order of increasing heating power; until all the third heat sources are closed at last, the heating power of the third heat sources is guaranteed to decrease sequentially.

In the second half cycle of T/2-T, the single second heat source is turned off first, and the single second heat source is turned off independently in the order of increasing heating power, and then the two second heat sources are turned off, and the two second heat sources are turned off according to the heating power Turn off independently in the order of increasing power, and then gradually increase the number of second heat sources that are turned off. If the number is n, then n second heat sources are turned off independently in the order of increasing heating power; until finally all heat sources are turned off, ensuring that the The heating power of the second heat source decreases sequentially. At the same time, according to the time sequence, the single first heat source is started first, and the single first heat source is started independently in the order of increasing heating power, and then the two first heat sources are started, and the two first heat sources are started independently in the order of increasing heating power , and then gradually increase the number of first heat sources activated, if the number is n, then the n first heat sources are independently activated in the order of increasing heating power; until finally all the first heat sources are activated to ensure the heating of the first heat sources The power increases sequentially. At the same time, according to the time sequence, the single third heat source is started first, and the single third heat source is started independently in the order of increasing heating power, and then the two third heat sources are started, and the two third heat sources are started independently in the order of increasing heating power , and then gradually increase the number of third heat sources activated, if the number is n, then the n third heat sources are independently activated in the order of increasing heating power; until finally all the third heat sources are activated to ensure the heating of the third heat sources The power increases sequentially.

For example, there are three second heat sources, which are respectively the second heat source V1, the second heat source V2 and the second heat source V3, and the heating powers are respectively W1, W2 and W3, wherein W1<W2<W3, W1+W2>W3; That is, the sum of the heating power of V1 and V2 is greater than the heating power of V3. In the first half cycle, V1, V2, V3 are started sequentially in chronological order, V1 plus V2, V1 plus V3, V2 plus V3, and then V1+V2+V3 , the order of closing in the next half cycle is V1, V2, V3, V1 plus V2, V1 plus V3, V2 plus V3.

There are three first heat sources, namely the first heat source Z1, the first heat source Z2 and the first heat source Z3, and the heating powers are respectively W1, W2 and W3, wherein W1<W2<W3, W1+W2>W3; namely The sum of the heating power of Z1 and Z2 is greater than the heating power of Z3. In the first half cycle, Z1, Z2, Z3 are turned off in order of time, Z1 plus Z2, Z1 plus Z3, Z2 plus Z3, and then Z1+Z2+Z3, The turn-on sequence in the second half cycle is Z1, Z2, Z3, Z1 plus Z2, Z1 plus Z3, Z2 plus Z3.

There are three third heat sources, namely the third heat source K1, the third heat source K2 and the third heat source K3, and the heating powers are respectively W1, W2 and W3, wherein W1<W2<W3, W1+W2>W3; namely The sum of the heating power of K1 and K2 is greater than the heating power of K3. In the first half cycle, turn off K1, K2, K3, K1 plus K2, K1 plus K3, K2 plus K3, and then K1+K2+K3 in order of time in the first half cycle. The turn-on sequence in the second half cycle is K1, K2, K3, K1 plus K2, K1 plus K3, K2 plus K3.

By gradually increasing and reducing the heating power of the heat source, the fluid flow is further promoted and the elastic vibration effect is increased. Through the above-mentioned time-varying heating power change, the fluid in the elastic tube bundle can be frequently evaporated, expanded and contracted, thereby continuously driving the vibration of the elastic tube bundle, thereby further realizing heating efficiency and descaling operation.

Preferably, in the first half cycle, the heating power of the heat source increases linearly, and in the second half cycle, the heating power of the heat source decreases linearly.

The linear change of heating power can be realized through the change of input current or voltage.

By setting multiple heat sources, the start-up of the gradually increasing number of heat sources is realized, and the linear change is realized.

Preferably, the period is 50-300 minutes, preferably 50-80 minutes; the average heating power of a single electric heating device is 2000-4000W.

Preferably, the heat source is an electric heater.

The linear change of heating power can be realized through the change of input current or voltage.

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

Preferably, the line connecting the axes of the left pipe, the right pipe and the middle pipe is on a straight line or on a plane.

Preferably, the diameters of the left pipe and the right pipe are smaller than that of the middle pipe. Preferably, the pipe diameter of the middle pipe is 1.4-1.5 times of the pipe diameters of the left pipe and the right pipe. Through the diameter setting of the left tube, right tube and middle tube, it can ensure that the fluid undergoes phase change and maintains the same or close transmission speed in the left tube, right tube and middle tube, thereby ensuring the uniformity of heat transfer.

Preferably, the connection position of the coiled pipe on the left tube box is lower than the connection position between the middle tube box and the coiled tube. This ensures that the steam can quickly enter the middle pipe box upwards. Similarly, the connection position of the coil at the right tube box is lower than the connection position between the middle tube box and the coil.

Although the present invention has been disclosed above with preferred embodiments, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, so the protection scope of the present invention should be based on the scope defined in the claims.

Claims (4)

1. The shell-and-tube heat exchanger 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 left tube group is communicated with the left tube group 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 group form a heating fluid closed cycle, the left tube and/or the central tube and/or the right tube are filled with a phase-change fluid, 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 tubes in a circular arc shape, the ends of the adjacent circular tubes are communicated, the plurality of circular tubes form a serial structure, and the ends of the circular tubes form a free end of the circular 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 surface where the axle center of the central pipe is located; 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 controller controls whether the first heat source, the second heat source and the third heat source are heated or not; the first heat source, the second heat source and the third heat source are respectively arranged into a plurality of electric heating components, each electric heating component is independently controlled, and the number of the electric heating components started is periodically changed along with the change of time.

2. The heat exchanger of claim 1, wherein the first heat source, the second heat source and the third heat source are respectively provided with n electric heating components, and in a half period of 0-T/2, when t=0, all of the n electric heating components of the first heat source and the third heat source are turned off, and all of the n electric heating components of the second heat source are turned on;

then, at intervals of T/2n, the first heat source and the third heat source respectively start an electric heating component, the second heat source turns off the electric heating component until the first heat source and the third heat source are all started at the time of T/2, and the second heat source is all turned off.

3. The heat exchanger of claim 1, wherein the second heat source activates one of the electrical heating elements every T/2n of a time period of T/2-T, and the first heat source and the third heat source are each turned off one of the electrical heating elements until the second heat source is fully activated at the end of the period T, and the first heat source and the third heat source are fully turned off.

4. The heat exchanger of claim 1, wherein each of the electrical heating elements of the first and third heat sources has the same heating power, and wherein each of the electrical heating elements of the second heat source has twice the power of the electrical heating elements of the first and third heat sources.