CN112985122B

CN112985122B - Four-fluid shell-and-tube heat exchanger with three-valve controlled opening amplitude variation

Info

Publication number: CN112985122B
Application number: CN201911308562.1A
Authority: CN
Inventors: 王逸隆; 郭春生; 冷学历
Original assignee: Qingdao University of Science and Technology
Current assignee: Qingdao University of Science and Technology
Priority date: 2019-12-17
Filing date: 2019-12-17
Publication date: 2023-07-21
Anticipated expiration: 2039-12-17
Also published as: CN112985122A

Abstract

The invention provides a four-fluid shell-and-tube heat exchanger with three valves for controlling opening amplitude variation, wherein the 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, the first valve, the second valve and the third valve are in data connection with a controller, and the controller is used for controlling the opening and closing of the first valve, the second valve and the third valve and controlling the flow of heat exchange fluid entering the first heat exchange tube, the second heat exchange tube and the third heat exchange tube; the controller controls the opening adjustment of the first valve, the second valve and the third valve, the amplitude of each adjustment is different, and the amplitude of the valve opening is gradually increased and reduced. According to the invention, the first fluid, the second fluid and the third valve are gradually increased and reduced, so that the fluid can be frequently evaporated, expanded and contracted in the elastic tube bundle, and the vibration of the elastic tube bundle is continuously driven, and the heat exchange efficiency and the descaling operation can be further realized.

Description

Four-fluid shell-and-tube heat exchanger with three-valve controlled opening amplitude variation

Technical Field

The present invention is a further improvement to the prior application, which applies 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 a novel invention for descaling a heat exchanger, which is used for a shell-and-tube heat exchanger based on research and development of Qingdao university of science and technology (application number 2019101874848).

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

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

The enhanced heat exchange is realized by utilizing the vibration of the fluid-induced heat transfer element, which is a form of passive enhanced heat exchange, and the strict prevention of the fluid vibration induction in the heat exchanger can be changed into the effective utilization of the vibration, so that the convective heat transfer coefficient of the transmission element under the low flow velocity is greatly improved, the dirt on the surface of the heat transfer element is restrained by utilizing the vibration, the dirt thermal resistance is reduced, and the composite enhanced heat transfer is realized.

In applications, it has been found that continuous heating can result in internal fluid formation stability, i.e., no or little fluid flow, or stable flow, resulting in greatly reduced heat exchange tube vibration performance, thereby affecting heat exchange tube descaling and heating efficiency. There is therefore a need for improvements in the heat exchangers described above.

The heat exchanger generally exchanges heat by two fluids, but has little research on four-fluid heat exchange, the application researches on four-fluid heat exchange, develops a novel induced vibration four-fluid shell-and-tube heat exchanger,

current shell and tube heat exchangers include dual headers, one header evaporating and one header condensing, forming vibratory descaling heat pipes. Thereby improving the heat exchange efficiency of the heat pipe and reducing scaling. However, the heat exchange uniformity of the heat pipe is not enough, only one side is condensed, but the heat exchange amount is small, so that improvement is needed, and a heat pipe system with a novel structure is developed. There is therefore a need for improvements in the heat exchangers described above.

Disclosure of Invention

The invention provides a four-fluid 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 heat exchange of four fluids, and the heat exchange tube periodically vibrates frequently, so that the heating efficiency is improved, and the good descaling and heating effects are realized.

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

a shell-and-tube heat exchanger of the vertical tube controlled by four fluid heat exchange, the said shell-and-tube heat exchanger includes the body, heat exchange part, shell side inlet connection pipe and shell side outlet connection pipe; the heat exchange component is arranged in the shell and is fixedly connected to the front tube plate and the rear tube plate; the shell side inlet connecting pipe and the shell side outlet connecting pipe are arranged on the shell; the shell side fluid enters from the shell side inlet connecting pipe, exchanges heat through the heat exchange component and exits from the shell side outlet connecting pipe;

the heat exchanger further comprises a first heat exchange tube, a second heat exchange tube and a third heat exchange tube, wherein the first heat exchange tube passes through the left side tube, the second heat exchange tube passes through the central tube, and the third heat exchange tube passes through the right side tube; the first heat exchange tube, the second heat exchange tube and the third heat exchange tube respectively flow through the first fluid, the second fluid and the 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, the first valve, the second valve and the third valve are in data connection with a controller, and the opening and the closing of the first valve, the second valve and the third valve are controlled by the controller to control the flow of heat exchange fluid entering the first heat exchange tube, the second heat exchange tube and the third heat exchange tube;

the controller controls the opening degree adjustment of the first valve, the second valve and the third valve, and the adjustment amplitude is different each time;

when T=0 in one half period of 0-T/2, the first valve and the third valve are closed, and the opening of the second valve is maximum; the flow rate per unit time of the fluid at the maximum opening of the first valve and the third valve is V8; the flow rate per unit time of the fluid at the maximum opening of the second valve is V9; the flow rates of the first fluid, the second fluid and the third fluid in unit time are adjusted n times;

then every T/2n time, the opening of the first valve and the third valve are controlled to be increased, the increasing amplitude of the opening of the first valve and the third valve is gradually increased along with the increase of times until the opening of the first valve and the third valve is maximum at the time of T/2, and the opening of the second valve is reduced at the same time, and the decreasing amplitude of the opening of the second valve is gradually reduced along with the increase of times until the second valve is closed at the time of T/2;

and in the half period of T/2-T, the second valve opening is increased every T/2n, the increasing amplitude of the valve opening gradually increases along with the increase of times until the second valve opening is maximum in the period T, meanwhile, the opening of the first valve and the third valve is reduced, and the decreasing amplitude of the first valve and the third valve opening gradually decreases along with the increase of times until the first valve and the third valve are closed in the T/2 time.

Preferably, v9=2×v8.

Preferably, the heat exchange member 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, 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 phase-change fluid, each tube group comprises a plurality of circular arc-shaped annular tubes, the ends of the adjacent annular tubes are communicated, the annular tubes form a serial structure, and the ends of the annular tubes form an annular tube free end; 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.

Preferably, the shell side fluid is a cold source and the first, second and third fluids are heat sources.

The invention has the following advantages:

1. according to the invention, the opening of the heating valve is controlled to be increased and the opening of the valve is controlled to be reduced periodically by the first valve, the second valve and the third valve, so that the phase-change fluid is heated to generate a continuously-variable volume state, and the free end of the heat exchange tube is further fully induced to generate vibration, thereby enhancing heat transfer.

2. According to the invention, the opening of the heating valve is controlled to be increased and the opening of the valve is controlled to be reduced periodically by the first valve, the second valve and the third valve, so that the phase-change fluid is heated to generate a continuously-variable volume state, and the free end of the heat exchange tube is further fully induced to generate vibration, thereby enhancing heat transfer.

3. The invention designs a novel heat exchanger with four fluid vertical structures, which can further improve the heat exchange effect and meet the heat exchange requirements of four fluids.

4. According to the invention, through controlling the intermittent opening and closing of the first valve, the second valve and the third valve, on one hand, continuous heat exchange of the shell side process is realized, and meanwhile, the elastic heat exchange tube can vibrate periodically and frequently, so that good descaling and heat exchange effects are realized.

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

6. The invention designs that the flowing directions of the first fluid, the third fluid and the second fluid are opposite, and the flowing of the phase-change fluid is further promoted, so that the heat transfer is enhanced.

7. The invention designs a layout diagram of a heat exchange component with a novel structure in a shell, optimizes the optimal relation between parameters of a heat exchange tube and flow, specific heat and the like of fluid through a large number of experiments and numerical simulation, and creatively fuses the flow, specific heat, temperature and target temperature of the heat exchange fluid into the dimensional design of a heat exchanger relative to the previous design, so that the heat exchange efficiency can be further improved.

8. By reasonably changing the inner diameter and the spacing of the tube bundles of the heat exchange tubes along the flowing direction of the fluid in the shell, the heat exchange efficiency is improved.

Description of the drawings:

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

FIG. 2 is a schematic cut-away view of a heat exchange component of the present invention.

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

Fig. 4 is a schematic view of a preferred construction of the heat exchanger.

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

Fig. 6 is a schematic view of a layout of heat exchange components disposed in a circular housing.

Fig. 7 is a schematic view of a preferred construction of the heat exchanger.

Fig. 8 is a schematic view of another preferred 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 tube orifice, 13 second tube orifice, left return tube 14, right return tube 15, front tube sheet 16, support 17, support 18, rear tube sheet 19, shell 20, 21, shell side inlet header, 22, shell side outlet header, 23, heat exchange unit, 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, comprising a housing 20, heat exchange means 23, a shell side inlet connection 21 and a shell side outlet connection 22; the heat exchange component 23 is arranged in the shell 20 and is 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 arranged on the shell 20; fluid enters from the shell side inlet connecting pipe 21, exchanges heat through the heat exchange component, and exits from the shell side outlet connecting pipe 22.

Preferably, the heat exchange member extends in a vertical direction. The heat exchangers are 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 member 23, which, as shown in fig. 2, comprises a central tube 8, a left tube 21, a right tube 22 and a tube group 1, the tube group 1 comprising a left tube group 11 and a right tube group 12, the left tube group 11 being in communication with the left tube 21 and the central tube 8, the right tube group 12 being in communication with the right tube 22 and the central tube 8, such that the central tube 8, the left tube 21, the right tube 22 and the tube group 1 form a heating fluid closed cycle, the left tube 21 and/or the central tube 8 and/or the right tube 22 being filled with a phase change fluid, each tube group 1 comprising a plurality of annular tubes 7 in the shape of a circular arc, the ends of adjacent annular tubes 7 being in communication such that the plurality of annular tubes 7 form a series structure, and such that the ends of the annular tubes 7 form annular tube free ends 3-6; 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 nozzle 10 and the second nozzle 13 are arranged on the same side of the central tube 8. Preferably, the position of the right tube group is a position in which the left tube group is rotated 180 degrees along the axis of the center tube.

The ends of the two ends of the center tube 8, the left tube 21 and the right tube 22 are arranged in the openings of the upper tube plates 16 and the lower tube plates 19 for fixation. The first nozzle 10 and the second nozzle 13 are located on opposite sides of the central tube 8.

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

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 is arranged through the left side tube 21, the second heat exchange tube 92 is arranged through the central tube 8, and the third heat exchange tube 93 is arranged through the right side tube 22. The first heat exchange tube 91, the second heat exchange tube 92, and the third heat exchange tube 93 flow through the first fluid, the second fluid, and the third fluid, respectively. The heat exchange of the four fluids can be carried out among the first fluid, the second fluid, the third fluid and the shell side fluid. The four fluid heat sources can be 1-3, and the residual fluid is a cold source, or the cold source can be 1-3, and the residual fluid is a heat source.

As an example of the preferred 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 side fluid are cold sources, the phase change fluid in the heat exchange component is subjected to phase change through heat exchange of the first fluid, so that the heat exchange shell side fluid is radiated outwards through the annular tube 7, meanwhile, vapor phase fluid enters the central tube and the right side tube to exchange heat with the second fluid and the third fluid, and condensed fluid after heat exchange returns to the right side tube through the return tube, so that four-fluid heat exchange is realized.

Preferably, the third fluid and the second fluid are heat sources, the first fluid and the shell side fluid are cold sources, the phase change fluid in the heat exchange component is subjected to phase change through heat exchange of the second fluid and the third fluid, so that the shell side fluid is subjected to heat exchange through the annular tube 7 in an outward radiating manner, meanwhile, the vapor phase fluid enters the left side tube to exchange heat with the first fluid, and the condensed fluid after heat exchange returns to the right tube box through the return tube, so that 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 heat exchange is carried out through the shell-side fluid, so that the fluid in the heat exchange component absorbs heat and exchanges heat with the first fluid, the second fluid and the third fluid, and heat exchange of four fluids 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 heat exchange is realized through the second fluid and the shell side fluid, so that 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 heat exchange is realized through the heat exchange of the first fluid, the third fluid and the shell side fluid, so that the heat exchange of four fluids 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 heat exchange is realized by the heat exchange 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 focuses on the case where the shell-side fluid is a cold source and the first, second, and third fluids are heat sources.

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, and the fluid expands in volume after being heated to form steam, and the steam is much larger in volume than water, so that the formed steam can quickly impact flow in the coil. Because the volume expansion and the steam flow can induce the free end of the annular tube to vibrate, the free end of the heat exchange tube transmits the vibration to surrounding heat exchange fluid in the vibration process, and the fluids can generate disturbance, so that the surrounding heat exchange fluid forms turbulence and damages a boundary layer, and the purpose of enhancing heat transfer is realized. The fluid flows back to the central tube through the return tube after the left and right side tubes condense and release heat. Conversely, the fluid can also be heated in the left and right side pipes, then enter the central pipe to be condensed and then return to the left and right side pipes for circulation through the return pipe.

According to the invention, the prior art is improved, the condensing (evaporating) header pipe and the pipe groups are respectively arranged into two pipes which are distributed left and right, so that the pipe groups distributed on the left side and the right side can perform vibration heat exchange and scale removal, thereby enlarging the heat exchange vibration area, enabling the vibration to be more uniform, enabling the heat exchange effect to be more uniform, increasing the heat exchange area and strengthening the heat exchange and scale removal effects.

The flow rate in this application refers to a flow rate per unit time, unless otherwise specified. The unit is m ³ /s。

Preferably, as shown in fig. 7 and 8, the first valve 24, the second valve 25 and the third valve 26 are provided at the inlets of the first heat exchange tube 91, the second heat exchange tube 92 and the third heat exchange tube 93, the first valve 24, the second valve 25 and the third valve 26 are in data connection with a controller, and the opening and closing and opening sizes of the first valve 24, the second valve 25 and the third valve 26 are controlled by the controller so as to control the flow rate of the heat exchange fluid entering the first heat exchange tube 91, the second heat exchange tube 92 and the third heat exchange tube 93.

It has been found in research and practice that heat exchange from a sustained power-stable heat source results in stability of the fluid formation of the internal heat exchange components, i.e., no or little fluid flow, or stable flow, resulting in a significant reduction in the vibrational performance of the annular tube 7, thereby affecting the descaling of the left tube bank 11 and the right tube bank 12 and the efficiency of heat exchange. There is a need for improvements in the heat exchangers described above as follows.

Preferably, the controller controls the flow rate per unit time of the heat exchange fluid in the first heat exchange tube, the second heat exchange tube, and the third heat exchange tube to periodically vary with time.

Preferably, the controller controls the opening and closing of the first valve 24, the second valve 25 and the third valve 26, so as to control the first fluid, the second fluid and the third fluid to exchange heat periodically and alternately along with the change of time.

Preferably, the controller controls the opening and closing rules of the first valve 24, the second valve 25 and the third valve 26 during one cycle time T as follows:

in the half period of 0-T/2, the opening of the first valve 24 and the third valve 26 is maximum, the second valve 25 is closed, namely the flow rates of the first fluid and the third fluid are maximum, and the flow rate of the second fluid is 0;

in the half period of T/2-T, the first valve 24 and the third valve 26 are closed, the opening of the second valve 25 is the largest, namely the flow rate of the second fluid is the largest, and the flow rates of the first fluid and the third fluid are 0.

Most preferably, the maximum opening of the first valve and the third valve is the same, which is 0.5 times the opening of the second valve. And ensures the balance of heat exchange.

As another preferable aspect, in one cycle time T, the flow rate per unit time of the first fluid is V1, the flow rate per unit time of the second fluid is V2, the flow rate per unit time of the third fluid is V3, and the change rule of V1, V2, V3 is as follows:

during the half period of 0-T/2, v1=v3=n, v2=0, i.e. the flow rate of the first fluid remains constant and the flow rate of the second fluid is 0;

in half period of T/2-T, v1=v3=0, v2=m. I.e. the first fluid flow is 0, no heat exchange, the second flow remains constant.

Wherein n and m are constant values, and the unit is m ³ And/s. Preferably, m=2n. Protection deviceAnd the heat exchange is balanced.

Preferably, T is 50-80 minutes.

Through foretell time variability's heat transfer, can make the frequent evaporation expansion of phase change fluid in the elastic tube bank, because the expansion and the flow direction of continuous periodic change steam have destroyed the stability of single heat transfer to constantly drive the vibration of elastic tube bank, thereby can further realize heat exchange efficiency and scale removal operation.

Compared with the prior application, the heat exchange mode ensures that the heat exchanger exchanges heat in the whole period, and the elastic tube bundles can vibrate frequently, so that the heat exchange efficiency and the descaling operation can be further realized.

Preferably, the controller controls the opening sizes of the first valve, the second valve and the third valve to be periodically changed with time.

Preferably, one period is T, and when t=0, the first valve and the third valve are closed, and the second valve has the largest opening in a half period of 0-T/2; v4 at the flow rate of the fluid at the maximum opening of the first valve and the third valve; v5 at the maximum opening of the second valve; the flow rates of the first fluid, the second fluid and the third fluid are adjusted in n times.

Then every T/2n time, the opening of the first valve and the third valve are controlled to be increased, so that the flow rate of the first fluid and the third fluid in unit time is increased by V4/n until the opening of the first valve is maximum in the T/2 time, and simultaneously, the opening of the second valve is reduced, so that the flow rate of the second fluid in unit time is reduced by V5/n until the second valve is closed in the T/2 time.

In the half period of T/2-T, the opening of the second valve is increased every T/2n time, so that the flow rate of the second fluid in unit time is increased by V5/n until the opening of the second valve is maximum in the period T, and simultaneously, the opening of the first valve and the opening of the third valve are reduced, so that the flow rates of the first fluid and the third fluid in unit time are reduced by V4/n until the second valve is closed in the period T/2.

Preferably, v5=2 times V4.

As another preferable aspect, if one cycle is T, then in a half cycle of 0 to T/2, when t=0, the flow rate per unit time of the first fluid and the third fluid is 0, and the flow rate per unit time of the second fluid is V6; the flow rates of the first fluid and the second fluid are adjusted n times.

Then every T/2n, the flow rate of the first fluid and the third fluid in unit time is increased by V6/n until the flow rate of the first fluid and the third fluid in unit time becomes V4 in the T/2 time, and the flow rate of the second fluid in unit time is reduced by V7/n until the flow rate of the second fluid in unit time in the T/2 time is 0.

In the half period of T/2-T, every T/2n time, the flow rate of the second fluid in unit time is increased by V7/n until the flow rate of the second fluid in unit time of the period T becomes V7, and the flow rates of the first fluid and the third fluid in unit time are reduced by V6/n until the flow rate of the fluid in unit time of the T/2 time is 0.

The above-mentioned flow rate change is preferably controlled by means of a first, a second and a third valve.

Preferably, v7=2 times V6.

Through foretell time variability's heat transfer, can make the fluid frequent evaporation expansion in the elastic tube bank, because the expansion and the flow direction of continuous periodic change steam have destroyed the stability of single heat transfer to constantly drive the vibration of elastic tube bank, thereby can further realize heat exchange efficiency and scale removal operation.

Preferably, the flow direction of the first fluid and the second fluid are opposite. The third fluid and the second fluid flow in opposite directions. The first fluid, the third fluid and the second fluid gradually flow from two sides to form a good heat exchange, so that the flow of the fluids is further promoted, and the elastic vibration effect is improved. Through the change of the flow rate of the time variability in unit time, the fluid can be frequently evaporated and expanded and contracted in the elastic tube bundle, so that the elastic tube bundle is continuously driven to vibrate, and the heat exchange efficiency and the descaling operation can be further realized.

Preferably, the controller controls the first valve, the second valve and the third valve to adjust the opening degree, and the amplitude of each adjustment is different.

Preferably, one period is T, and when t=0, the first valve and the third valve are closed, and the second valve has the largest opening in a half period of 0-T/2; the flow rate per unit time of the fluid at the maximum opening of the first valve and the third valve is V8; the flow rate per unit time of the fluid at the maximum opening of the second valve is V9; the flow rates of the first fluid, the second fluid and the third fluid per unit time are adjusted in n times.

And then the opening of the first valve and the third valve controlled by the first valve and the third valve are increased at intervals of T/2n, the increasing amplitude of the opening of the first valve and the third valve is gradually increased along with the increase of times until the opening of the first valve and the third valve is maximum at the time of T/2, and the opening of the second valve is reduced at the same time, and the decreasing amplitude of the opening of the second valve is gradually reduced along with the increase of times until the second valve is closed at the time of T/2.

The flow rate of the first fluid, the second fluid and the third valve is gradually increased to reduce the flow rate of the first fluid, the second fluid and the third valve in unit time, so that the flow of the fluid is further promoted, and the elastic vibration effect is improved. Through the change of the time-variable heat exchange power, fluid can be enabled to be frequently evaporated and expanded and contracted in the elastic tube bundle, so that the elastic tube bundle is continuously driven to vibrate, and heat exchange efficiency and descaling operation can be further achieved.

Preferably, the flow rate of the first fluid and the third fluid per unit time increases linearly in the first half cycle, and the flow rate of the first fluid and the third fluid per unit time decreases linearly in the second half cycle.

Preferably, v9=2×v8.

Preferably, the period is 50 to 300 minutes, preferably 50 to 80 minutes; the average flow rate of the first fluid, the second fluid and the third fluid is 0.5-5m/s, preferably 1-3m/s.

Preferably, the average temperatures of the first fluid, the second fluid, and the third fluid are the same, the average flow rate per unit time of the first fluid is equal to the average flow rate per unit time of the third fluid, and the average flow rate per unit time of the first fluid is 0.5 times the average 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 is preferred, the first, second and third fluids have a common inlet header 27 and outlet header 28, as shown in fig. 4. The fluid enters the inlet header first, then 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 best shown 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 tube, the second heat exchange tube and the third heat exchange tube through the inlet headers for heat exchange, and then flows out through the respective outlet headers.

Preferably, return pipes communicated with the central pipes are arranged at the bottoms of the right pipe box and the left pipe box, so that the condensed fluid in the first pipe box and the second pipe box can flow rapidly.

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

The periodic frequent vibration of the elastic coil pipe can be realized through the alternate heating of the three fluids in the period, so that good descaling and heating effects are realized, and the heating power is basically the same in time.

Preferably, the annular tubes of the left tube group are distributed by taking the axis of the left tube as the center of a circle, and the annular tubes of the right tube group are distributed by taking the axis of the right tube as the center of a circle. Through setting up left and right sides pipe as the centre of a circle, the distribution of assurance annular pipe that can be better for vibration and heating are even.

Preferably, the tube group is plural.

Preferably, the center pipe 8, the left pipe 21, and the right pipe 22 are arranged in 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 staggered distribution, vibration heat exchange and descaling can be performed at different heights, so that vibration is more uniform, and heat exchange and descaling effects are enhanced.

Preferably, the tube group 2 (for example, the same side (left side or right side)) is provided in plural along 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)) is increased along the direction of the gas flow in the shell side.

Preferably, the annular tube diameter of the tube group (e.g., on the same side (left or right)) is increased in magnitude along the direction of gas flow in the shell side.

Through the pipe diameter range increase of the heat exchange pipe, the shell side gas outlet position can be guaranteed to fully exchange heat, a heat exchange effect similar to countercurrent is formed, the heat transfer effect is further enhanced, the overall vibration effect is uniform, the heat exchange effect is increased, and the heat exchange effect and the descaling effect are further improved. Experiments show that better heat exchange effect and descaling effect can be obtained by adopting the structural design.

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

Preferably, the spacing between the tube sets on the same side (left or right) is increasing with decreasing amplitude along the direction of gas flow within the shell side.

Through the increase of the interval amplitude of the heat exchange tubes, the shell side gas outlet position can be guaranteed to exchange heat fully, a heat exchange effect similar to countercurrent is formed, the heat transfer effect is further enhanced, the overall vibration effect is uniform, the heat exchange effect is increased, and the heat exchange effect and the descaling effect are further improved. Experiments show that better heat exchange effect and descaling effect can be obtained by adopting the structural design.

In the experiments, it was found that the pipe diameters, distances, and pipe diameters of the left side pipe 21, the right side pipe 22, the center pipe 8, and the ring pipe may have an influence on heat exchange efficiency and uniformity. If the distance between the headers is too large, the heat exchange efficiency is too poor, the distance between the annular pipes is too small, the annular pipes are distributed too densely, the heat exchange efficiency is also affected, the sizes of the headers and the heat exchange pipes affect the volume of the contained liquid or steam, and vibration of the free ends is affected, so that heat exchange is affected. The pipe diameters, distances and pipe diameters of the left side pipe 21, the right side pipe 22, the center pipe 8 and the annular pipe have a certain relationship.

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

the distance between the center of the center tube 8 and the center of the left tube 21 is equal to the distance between the center of the center 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 radius of the pipe diameter of the left side pipe 21, the pipe diameter of the central pipe 8 and the radius of the right side pipe 22 are R, 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 satisfied:

r1/r2=a.ln (R/M) +b; wherein a, b are parameters and Ln is a logarithmic function, wherein 0.5785 < a < 0.5805,1.6615 < b < 1.6625; preferably, a=0.579 and b= 1.6621.

Preferably, 35 < R < 61mm;114 < L < 190mm;69 < R1 < 121mm,119 < R2 < 201mm. M=2l.

Preferably, the number of annular tubes of the tube group is 3 to 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 10-40mm; preferably 15 to 35mm, and more preferably 20 to 30mm.

Preferably, the centers of the left side tube 21, the right side tube 22 and the center tube 8 are aligned.

Preferably, the arc between the ends of the free ends 3, 4 is 95-130 degrees, preferably 120 degrees, centered on the central axis of the left tube. The free ends 5, 6 and the free ends 3, 4 have the same radian. By the design of the preferable included angle, the vibration of the free end is optimized, so that the heating efficiency is optimized.

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

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

By providing the tube bundle of the tube group 1 with an elastic tube bundle, the heat exchange coefficient can be further improved.

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

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

The heat exchanger shown in fig. 6 has a housing of circular cross section, and the plurality of heat exchange members are disposed in the circular housing. Preferably, three heat exchange components are arranged in the shell, the center of the central tube of the heat exchange component is positioned at the middle point of an inscribed regular triangle with a circular section, the connecting line of the centers of the central tube forms a regular triangle, and the extension line of the connecting line of the centers of the left side tube, the right side tube and the central tube forms a regular triangle. Through such setting, can make the interior fluid of heater fully reach vibrations and heat transfer purpose, improve the heat transfer effect.

Through numerical simulation and experiments, the size of the heat exchange component and the diameter of the circular section have great influence on the heat exchange effect, the heat exchange component is oversized to cause the adjacent interval to be too small, the space formed in the middle is too large, the middle heating effect is poor, the heating is uneven, and the heat exchange component is undersized to cause the adjacent interval to be too large, so that the whole heating effect is poor. Therefore, the invention obtains the optimal dimensional relationship through a large number of numerical simulation and experimental researches.

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

10*(L1/L2)＝d*(10*R1/R2)-e*(10*R1/R2) ² -f; where 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;

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

More preferably 0.30 < L1/L2 < 0.4.

Through the layout of the structural optimization of the three heat exchange components, the whole heat exchange effect can reach the optimal heat exchange effect.

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

Preferably, the axes of the left side tube, the right side tube and the middle tube are connected on 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. 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 pipe diameter setting of left side pipe, right side pipe and intermediate tube, can guarantee that the fluid carries out the phase transition and keeps the same or nearly transmission speed at left side pipe, right side pipe and intermediate tube to guarantee the homogeneity of heat transfer.

Preferably, the connection position of the coil pipe on the left side pipe box is lower than the connection position of the middle pipe box and the coil pipe. This ensures that steam can quickly pass upwardly into the middle tube box. Similarly, the connection position of the coil pipe on the right side pipe box is lower than the connection position of the middle pipe box and the coil pipe

While the invention has been described in terms of preferred embodiments, the invention is not so limited. Various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention, and the scope of the invention should be assessed accordingly to that of the appended claims.

Claims

1. A four-fluid shell-and-tube heat exchanger with three-valve controlled opening amplitude variation comprises a shell, a heat exchange component, a shell side inlet connecting pipe and a shell side outlet connecting pipe; the heat exchange component is arranged in the shell and is fixedly connected to the front tube plate and the rear tube plate; the shell side inlet connecting pipe and the shell side outlet connecting pipe are arranged on the shell; the shell side fluid enters from the shell side inlet connecting pipe, exchanges heat through the heat exchange component and exits from the shell side outlet connecting pipe; the heat exchange component comprises a central tube, a left tube, a right tube and a tube group, wherein the tube group comprises a left tube group and a right 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 group and the central tube, so that the central tube, the left tube, the right tube group 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 phase-change fluid, each tube group comprises a plurality of circular tubes in a circular arc shape, the end parts of the adjacent circular tubes are communicated, the plurality of circular tubes form a serial structure, and the end parts of the circular tubes form a free end of the circular tube; 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;

in a half period of T/2-T, the second valve opening is increased every T/2n, the increasing amplitude of the valve opening is gradually increased along with the increase of times until the second valve opening is maximum in the period T, meanwhile, the opening of the first valve and the third valve is reduced, and the decreasing amplitude of the first valve and the third valve opening is gradually reduced along with the increase of times until the first valve and the third valve are closed in the T/2 time.

2. A shell and tube heat exchanger as claimed in claim 1, wherein v9=2×v8.

3. The shell and tube heat exchanger as set forth in claim 1, wherein the shell side fluid is a cold source and the first fluid, the second fluid and the third fluid are heat sources.