CN112665426B - Shell-and-tube heat exchanger of many casees pressure difference control - Google Patents
Shell-and-tube heat exchanger of many casees pressure difference control Download PDFInfo
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Abstract
The invention provides a shell-and-tube heat exchanger, wherein a pressure detection element is arranged in a heat exchange component and used for detecting the pressure in the heat exchange component, the pressure detection element is in data connection with a controller, the heat exchanger comprises a descaling process, and the controller controls an electric heater to heat or not according to the detected pressure difference in the descaling process so as to enable a tube bundle to vibrate; the controller extracts pressure data according to the time sequence, obtains the pressure difference or the accumulation of the pressure difference change through the comparison of the pressure data of adjacent time periods, and controls the electric heater to stop heating or continue heating when the pressure difference or the accumulation of the pressure difference change is lower than a threshold value; if the pressure of the previous time period is P1 and the pressure of the adjacent following time period is P2, if P1< P2, then the controller controls the electric heater to stop heating when the pressure is lower than the threshold value; if P1> P2, the controller controls the electric heater to heat when the threshold value is lower. According to the invention, the pressure difference of the front time period and the rear time period or the accumulated pressure difference detected by the pressure sensing element can be used for judging that the evaporation of the fluid in the device is basically saturated through the pressure difference, so that the device vibrates.
Description
Technical Field
The invention relates to a shell-and-tube heat exchanger, in particular to a shell-and-tube heat exchanger for intermittent vibration descaling.
Background
The shell-and-tube heat exchanger is widely applied to industries such as chemical industry, petroleum industry, refrigeration industry, nuclear energy industry and power industry, and due to the worldwide energy crisis, the demand of the heat exchanger in industrial production is more and more, and the quality requirement of the heat exchanger is higher and more. In recent decades, although compact heat exchangers (plate type, plate fin type, pressure welded plate type, etc.), heat pipe type heat exchangers, direct contact type heat exchangers, etc. have been rapidly developed, because the shell and tube type heat exchangers have high reliability and wide adaptability, they still occupy the domination of yield and usage, and according to relevant statistics, the usage of the shell and tube type heat exchangers in the current industrial devices still accounts for about 70% of the usage of all heat exchangers.
After the shell-and-tube heat exchanger is scaled, the heat exchanger is cleaned by adopting conventional modes of steam cleaning, back flushing and the like, and the production practice proves that the effect is not good. The end socket of the heat exchanger can only be disassembled, and a physical cleaning mode is adopted, but the mode is adopted for cleaning, so that the operation is complex, the consumed time is long, the investment of manpower and material resources is large, and great difficulty is brought to continuous industrial production.
The mode of passively strengthening heat exchange is to strictly prevent the fluid vibration induction in the heat exchanger from being changed into effective utilization of vibration, so that the convective heat transfer coefficient of the transmission element at low flow speed is greatly improved, dirt on the surface of the heat transfer element is restrained by vibration, the thermal resistance of the dirt is reduced, and the composite strengthened heat transfer is realized.
In application, it is found that continuous heating can cause the internal fluid to form stability, i.e. the fluid does not flow or has little fluidity, or the flow is stable, so that the vibration performance of the heat exchange tube is greatly weakened, thereby affecting the descaling of the heat exchange tube and the heating efficiency.
Current shell and tube heat exchangers include dual headers, one header evaporating and one header condensing, thereby forming a vibrating descaled heat pipe. Thereby improving the heat exchange efficiency of the heat pipe and reducing scaling. However, the heat pipe has insufficient uniformity of heat exchange, only one side is used for condensation, and the heat exchange amount is small, so that improvement is needed to develop a heat pipe system with a novel structure. There is therefore a need for improvements to the above-described heat exchangers. In this regard, we have developed a new shell and tube heat exchanger capable of producing periodic or parametric-size vibrations and have already filed a patent application.
However, in practice it has been found that adjusting the vibration of the tube bundle by a fixed periodic variation or parameter magnitude results in hysteresis and excessively long or short periods. Therefore, the invention improves the previous application and intelligently controls the vibration, so that the fluid in the fluid can realize frequent vibration, and good descaling and heating effects can be realized.
Disclosure of Invention
The invention provides an electric heating shell-and-tube heat exchanger with a novel structure, aiming at the defects of the shell-and-tube heat exchanger in the prior art. The shell-and-tube heat exchanger can realize the periodic frequent vibration of the heat exchange tube, and improves the heating efficiency, thereby realizing good descaling and heating effects.
In order to achieve the purpose, the invention adopts the following technical scheme:
a shell-and-tube heat exchanger comprises a shell, wherein tube plates are respectively arranged at two ends of the shell, heat exchanging components are arranged in the shell and comprise a central tube, a left tube, a right tube and tube groups, each 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 groups form heating fluid closed circulation, an electric heater is arranged in the central tube, and the right tube group is rotated by 180 degrees along the axis of the central tube; the heat exchanger is characterized in that a pressure detection element is arranged in the heat exchange component and used for detecting the pressure in the heat exchange component, the pressure detection element is in data connection with a controller, the heat exchanger comprises a descaling process, and the controller controls whether the electric heater heats or not according to the detected pressure difference in the descaling process to enable the tube bundle to vibrate;
the controller extracts pressure data according to the time sequence, obtains the pressure difference or the accumulation of the pressure difference change through the comparison of the pressure data of adjacent time periods, and controls the electric heater to stop heating or continue heating when the pressure difference or the accumulation of the pressure difference change is lower than a threshold value;
if the pressure of the previous time period is P1 and the pressure of the adjacent following time period is P2, if P1< P2, then the controller controls the electric heater to stop heating when the pressure is lower than the threshold value; if P1> P2, the controller controls the electric heater to heat when the threshold value is lower.
Preferably, the number of the pipe groups is multiple, each pipe group comprises a plurality of circular arc-shaped annular pipes, the end parts of the adjacent annular pipes are communicated, the plurality of annular pipes form a serial structure, and the end parts of the annular pipes form free ends of the annular pipes; 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 and second outlets are disposed on opposite sides of the central tube.
Preferably, the annular pipes of the left pipe group are distributed by taking the axis of the left pipe as the center of a circle, and the annular pipes of the right pipe group are distributed by taking the axis of the right pipe as the center of a circle.
The invention has the following advantages:
1. according to the invention, through the pressure difference between the previous time and the next time or the accumulated pressure difference detected by the pressure sensing element, the evaporation of the fluid in the pipe can be judged to be basically saturated through the pressure difference, and the volume of the fluid in the pipe is basically not changed greatly. So that the fluid undergoes a volume reduction to thereby realize vibration. When the pressure difference is reduced to a certain degree, the internal fluid starts to enter a stable state again, and at the moment, the fluid needs to be heated so as to be evaporated and expanded again, so that the electric heater needs to be started for heating.
2. The invention provides a vibrating tube bundle shell-and-tube heat exchanger with a novel structure, which increases the vibration range of a tube bundle by arranging more tube groups in a limited space, thereby strengthening heat transfer and enhancing descaling.
3. The heating efficiency can be further improved by the arrangement of the pipe diameter and the interval distribution of the pipe groups in the length direction.
4. The invention optimizes the optimal relationship of the parameters of the shell-and-tube heat exchanger through a large amount of experiments and numerical simulation, thereby realizing the optimal heating efficiency.
5. The invention designs a triangular layout diagram of a multi-heat exchange component with a novel structure, optimizes the structural parameters of the layout, and can further improve the heating efficiency through the layout.
Description of the drawings:
fig. 1 is a schematic view of a housing structure.
Fig. 2 is a top view of a heat exchange member of the present invention.
Fig. 3 is a front view of the heat exchange member of the present invention.
Fig. 4 is a front view of another embodiment of a heat exchange member of the present invention.
Fig. 5 is a dimensional structure schematic diagram of the heat exchange component of the invention.
Fig. 6 is a schematic layout of the heat exchange member of the present invention in a circular cross-section heater.
Fig. 7 is a schematic diagram of the control structure according to the parameter difference of the data.
In the figure: 1. the device comprises a tube group, a left tube group 11, a right tube group 12, 21, a left tube 22, a right tube 3, a free end 4, a free end 5, a free end 6, a free end 7, a ring tube 8, a central tube 9, an electric heater, a first tube opening 10, a second tube opening 13, a left return tube 14, a right return tube 15, a front tube plate 16, a support 17, a support 18, a rear tube plate 19, shells 20, 24, a shell side inlet connecting tube 25, a shell side outlet connecting tube and a heat exchange component 23.
Detailed Description
A shell-and-tube heat exchanger, as shown in fig. 1, comprises a shell 20, a heat exchange component 23, a shell-side inlet connecting pipe 21 and a shell-side outlet connecting pipe 22; the heat exchange component 23 is arranged in the shell 20 and fixedly connected to the front tube plate 16 and the rear tube plate 19; the shell side inlet connecting pipe 24 and the shell side outlet connecting pipe 25 are both arranged on the shell 20; fluid enters from the shell side inlet connecting pipe 24, exchanges heat through the heat exchange part and exits from the shell side outlet connecting pipe 25.
Preferably, the heating member 23 extends in a horizontal direction. The heat exchanger is arranged in the horizontal direction.
Fig. 2 shows a top view of a heat exchange part 23, which comprises a central tube 8, a left tube 21, a right tube 22 and tube groups 1, wherein the tube groups 1 comprise a left tube group 11 and a right tube group 12, the left tube group 11 is communicated with the left tube 21 and the central tube 8, the right tube group 12 is communicated with the right tube 22 and the central tube 8, so that the central tube 8, the left tube 21, the right tube 22 and the tube groups 1 form a closed circulation of heating fluid, the central tube 8 is filled with phase change fluid, an electric heater 9 is arranged in the central tube 8, each tube group 1 comprises a plurality of circular arc-shaped annular tubes 7, the ends of the adjacent annular tubes 7 are communicated, so that the plurality of annular tubes 7 form a serial structure, and the ends of the annular tubes 7 form free ends 3-6 of the annular tubes; the central tube comprises a first tube orifice 10 and a second tube orifice 13, the first tube orifice 10 is connected with the inlet of the left tube group 11, the second tube orifice 13 is connected with the inlet of the right tube group 12, the outlet of the left tube group 11 is connected with the left tube 21, and the outlet of the right tube group 12 is connected with the right tube 22; the first orifice 10 and the second orifice 13 are arranged on opposite sides of the central tube 8.
The ends of the two ends of the center tube 8, the left tube 21 and the right tube 22 are disposed in the openings of the front and rear tube plates 16, 19 for fixation.
Preferably, a left return pipe 14 is arranged between the left pipe 21 and the central pipe 8, and a right return pipe 14 is arranged between the right pipe 22 and the central pipe 8. Preferably, the return pipe is arranged at the end of the central pipe. Preferably both ends of the central tube
The fluid is heated and evaporated in the central tube 8, flows to the left and right headers 21 and 22 along the annular tube bundle, and is heated to expand in volume, so that steam is formed, and the volume of the steam is far larger than that of water, so that the formed steam can flow in the coil in a rapid impact manner. Because of volume expansion and steam flow, the free end of the annular tube can be induced to vibrate, the vibration is transmitted to the surrounding heat exchange fluid by the free end of the heat exchange tube in the vibration process, and the fluid can also generate disturbance, so that the surrounding heat exchange fluid forms disturbance flow, a boundary layer is damaged, and the purpose of enhancing heat transfer is realized. The fluid is condensed and released heat in the left and right side pipes and then flows back to the central pipe through the return pipe.
According to the invention, the prior art is improved, and the condensation collecting pipe and the pipe groups are respectively arranged into two pipes which are distributed on the left side and the right side, so that the pipe groups distributed on the left side and the right side can perform vibration heat exchange descaling, the heat exchange vibration area is enlarged, the vibration can be more uniform, the heat exchange effect is more uniform, the heat exchange area is increased, and the heat exchange and descaling effects are enhanced.
Preferably, the annular pipes of the left pipe group are distributed by taking the axis of the left pipe as the center of a circle, and the annular pipes of the right pipe group are distributed by taking the axis of the right pipe as the center of a circle. The left side pipe and the right side pipe are arranged to be circle centers, so that the distribution of the annular pipes can be better guaranteed, and the vibration and the heating are uniform.
Preferably, the tube group is plural.
Preferably, the position of the right tube group (including the right tube) is a position of the left tube group (including the left tube) rotated by 180 degrees (angle) along the axis of the center tube. Through such setting, can make the annular pipe distribution of heat transfer reasonable more even, improve the heat transfer effect.
Preferably, the headers 8, 21, 22 are provided along the longitudinal direction.
Preferably, the left tube group 21 and the right tube group 22 are staggered in the longitudinal direction, as shown in fig. 3. Through the staggered distribution, can make to vibrate heat transfer and scale removal on different length for the vibration is more even, strengthens heat transfer and scale removal effect.
Preferably, the tube group 2 is provided in plural (for example, the same side (left side or right side)) along the length direction of the center tube 8, and the tube diameter of the tube group 2 (for example, the same side (left side or right side)) becomes larger along the flow direction of the fluid in the shell side.
Preferably, the pipe diameter of the annular pipe of the pipe group (such as the same side (left side or right side)) is continuously increased along the flowing direction of the fluid in the shell side.
The pipe diameter range through the heat exchange tube increases, can guarantee that shell side fluid outlet position fully carries out the heat transfer, forms the heat transfer effect like the adverse current, further strengthens the heat transfer effect moreover for whole vibration effect is even, and the heat transfer effect increases, further improves heat transfer effect and scale removal effect. Experiments show that better heat exchange effect and descaling effect can be achieved by adopting the structural design.
Preferably, the tube group on the same side (left side or right side) is provided in plural along the length direction of the center tube 8, and the distance between the adjacent tube groups on the same side (left side or right side) becomes smaller along the flow direction of the fluid in the shell side.
Preferably, the spacing between the tube banks on the same side (left or right) in the direction of fluid flow in the shell side is increased by a decreasing amount.
The interval amplitude through the heat exchange tube increases, can guarantee that shell side fluid outlet position fully carries out the heat transfer, forms the heat transfer effect like the adverse current, further strengthens the heat transfer effect moreover for the whole vibration effect is even, and the heat transfer effect increases, further improves heat transfer effect and scale removal effect. Experiments show that better heat exchange effect and descaling effect can be achieved by adopting the structural design.
In tests it was found that the tube diameter, distance of the left and right side tubes 21, 22 and the central tube 8 and the tube diameter of the ring tubes can have an effect on the heat exchange efficiency and uniformity. If the distance between the collector is too big, then heat exchange efficiency is too poor, and the distance between the ring shape pipe is too little, then the ring shape pipe distributes too closely, also can influence heat exchange efficiency, and the pipe diameter size of collector and heat exchange tube influences the volume of the liquid or the steam that holds, then can exert an influence to the vibration of free end to influence the heat transfer. Therefore, the pipe diameters and distances of the left pipe 21, the right pipe 22, the central pipe 8 and the pipe diameters of the ring pipes have a certain relationship.
The invention provides an optimal size relation summarized by numerical simulation and test data of a plurality of heat pipes with different sizes. Starting from the maximum heat exchange amount in the heat exchange effect, nearly 200 forms are calculated. The dimensional relationship is as follows:
the distance between the center of the central tube 8 and the center of the left tube 21 is equal to the distance between the center of the central tube 8 and the center of the right tube 21, L, the tube diameter of the left tube 21, the tube diameter of the central tube 8, and the radius of the right tube 22 are R, the radius of the axis of the innermost annular tube in the annular tubes is R1, and the radius of the axis of the outermost annular tube is R2, so that the following requirements are met:
R1/R2＝a*(R/L)2-b (R/L) + c; wherein a, b, c are parameters, wherein 4.834<a<4.835，1.390<b<1.391，0.5585<c<0.5590, respectively; preferably, a is 4.8344, b is 1.3906, and c is 0.5587.
Preferably, 34< R <61 mm; 114< L <191 mm; 69< R1<121mm, 119< R2<201 mm.
Preferably, the number of annular tubes of the tube set is 3-5, preferably 3 or 4.
Preferably, 0.57< R1/R2< 0.61; 0.3< R/L < 0.32.
Preferably, 0.583< R1/R2< 0.60; 0.304< R/L < 0.316.
Preferably, the radius of the annular tube is preferably 10-40 mm; preferably 15 to 35mm, more preferably 20 to 30 mm.
Preferably, the centers of the left tube 21, the right tube 22 and the center tube 8 are on a straight line.
Preferably, the radian measured between the ends of the free ends 3, 4 with respect to the center axis of the left tube is 95-130 degrees, preferably 120 degrees. The same applies to the curvature of the free ends 5, 6 and the free ends 3, 4. Through the design of the preferable included angle, the vibration of the free end is optimal, and therefore the heating efficiency is optimal.
The heating power of the electric heater is preferably 1000-2000W, and more preferably 1500W.
Preferably, the box body has a circular cross section, and is provided with a plurality of electric heating devices, wherein one electric heating device is arranged at the center of the circular cross section and the other electric heating devices are distributed around the center of the circular cross section.
Preferably, the tube bundle of the tube bank 1 is an elastic tube bundle.
The heat exchange coefficient can be further improved by arranging the tube bundle of the tube group 1 with an elastic tube bundle.
Further preferably, the electric heater is an electric heating rod.
The number of the pipe groups 1 is multiple, and the plurality of pipe groups 1 are in a parallel structure.
The heat exchanger shown in fig. 6 has a circular cross-sectional housing in which the plurality of heat exchanging elements are disposed. Preferably, the number of the heat exchange components is three, the center of the central tube of each heat exchange component is positioned in an inscribed regular triangle with a circular cross section, the connecting lines of the centers of the central tubes form a regular triangle, the upper part of each central tube is provided with one heat exchange component, the lower part of each central tube is provided with two heat exchange components, and the connecting lines formed by the centers of the left tube, the right tube and the central tube of each heat exchange component are of a parallel structure. Through such setting, can make and to fully reach vibrations and heat transfer purpose in can making the heater, improve the heat transfer effect.
Learn through numerical simulation and experiment, heat transfer part's size and circular cross-section's diameter have very big influence to the heat transfer effect, heat transfer part size too big can lead to adjacent interval too little, the space that the centre formed is too big, middle heating effect is not good, the heating is inhomogeneous, on the same way, heat transfer part size undersize can lead to adjacent interval too big, leads to whole heating effect not good. Therefore, the invention obtains the optimal size relation through a large amount of numerical simulation and experimental research.
The distance between the centers of the left side pipe and the right side pipe is L1, the side length of the inscribed regular triangle is L2, the radius of the axis of the innermost annular pipe in the annular pipes is R1, and the radius of the axis of the outermost annular pipe is R2, so that the following requirements are met:
10*(L1/L2)＝d*(10*R1/R2)-e*(10*R1/R2)2-f; wherein d, e, f are parameters,
34.71<d<34.72,2.9315<e<2.9320,99.338<f<99.345；
further preferably, d-34.716, e-2.9319, f-99.342;
with 720< L2<1130mm preferred. Preferably 0.58< R1/R2< 0.62.
Further preferred is 0.30< L1/L2< 0.4.
Preferably, the centers of the left tube 21, the right tube 22 and the center tube 8 are on a straight line.
Through the layout of the three heat exchange component structure optimization, the whole heat exchange effect can reach the best heat exchange effect.
It has been found in research and practice that a constant and stable heat source results in a fluid-forming stability of the internal heat exchange components, i.e. the fluid is not flowing or is less fluid, or the flow is stable, resulting in a significantly reduced vibration performance of the tube bank 1, which affects the efficiency of the descaling and heating of the tube bank 1. Therefore, the following improvements are required for the heat pipe.
In the prior application of the inventor, a heating mode controlled according to the parameter is provided, and the vibration of the heat exchange tube is continuously promoted through the heating mode controlled according to the parameter, so that the heating efficiency and the descaling effect are improved. However, adjusting the vibration of the tube bundle by the fixturing parameter size can result in hysteresis and too long or too short a cycle. The present invention therefore improves on the previous application by intelligently controlling the vibration so that frequent vibration of the fluid inside can be achieved, resulting in good descaling and heating.
Aiming at the defects in the technology researched in the prior art, the invention provides a novel electric heating heat exchanger capable of intelligently controlling vibration. The heat exchanger can improve the heating efficiency, thereby realizing good descaling and heating effects.
Preferably, the heat exchange is carried out in the descaling process in the manner described above.
Self-regulation vibration based on pressure
Preferably, a pressure detection element is arranged in the heat exchange component and used for detecting the pressure in the heat exchange component, the controller extracts pressure data according to a time sequence, the pressure data in adjacent time periods are compared to obtain the pressure difference or the accumulation of the pressure difference change, and when the pressure difference or the accumulation of the pressure difference change is lower than a threshold value, the controller controls the electric heater to stop heating or continue heating.
Through the pressure difference of the previous and subsequent time periods or the accumulated pressure difference detected by the pressure sensing element, the evaporation of the fluid inside can be judged to be basically saturated through the pressure difference, and the volume of the fluid inside is basically not changed greatly. So that the fluid undergoes volume reduction to thereby realize vibration. When the pressure difference is reduced to a certain degree, the internal fluid starts to enter a stable state again, and at the moment, the fluid needs to be heated so as to be evaporated and expanded again, so that the electric heater needs to be started for heating.
The stable state of the fluid is judged according to the pressure difference or the accumulation of the pressure difference change, so that the result is more accurate, and the problem of error increase caused by aging due to the running time problem is solved.
Preferably, if the pressure of the preceding period is P1 and the pressure of the adjacent following period is P2, if P1< P2, the controller controls the electric heater to stop heating when the pressure is lower than the threshold value; if P1> P2, the controller controls the electric heater to heat when the threshold value is lower.
The current electric heater is determined to be in a heating state or a non-heating state through sequential pressure size judgment, so that the running state of the electric heater is determined according to different conditions.
Preferably, if the pressure of the preceding time period is P1, the pressure of the adjacent following time period is P2, and if P1 is P2, heating is judged according to the following:
if the pressure P1 is greater than the pressure of the first data, the controller controls the electric heater to stop heating when the pressure P is lower than the threshold value; wherein the first data is greater than the pressure of the phase change fluid after the phase change; preferably the first data is a pressure at which the phase change fluid is substantially phase-changed;
if P1 is less than or equal to the pressure of the second data, which is less than or equal to the pressure at which the phase change fluid does not undergo the phase change, then below the threshold, the controller controls the electric heater to continue heating.
The first data is pressure data in a fully heated state, and the second data is pressure data in the absence of heating or in the beginning of heating. The judgment of the pressure is also used for determining whether the current electric heater is in a heating state or a non-heating state, so that the operation state of the electric heater is determined according to different conditions.
Preferably, the pressure detecting elements are arranged in the central tube 8 and/or the left side tube 21 and/or the right side tube 22.
Preferably, the pressure detecting elements are disposed within the center tube 8 and the left and right side tubes 21 and 22. The average of the pressures of the three channel boxes can be selected as regulating data.
Preferably, the pressure detecting element is provided at the free end. Through setting up at the free end, can perceive the pressure variation of free end to realize better control and regulation.
Preferably, the pressure sensing element is disposed at the free end. Through setting up at the free end, can perceive the pressure variation of free end to realize better control and regulation.
Preferably, the number of the pressure sensing elements is n, and the pressure P in the current time period is calculated in sequenceiPressure Q of the preceding periodi-1Difference D ofi＝Pi-Qi-1And for n pressure differences DiPerforming arithmetic cumulative summation
When the value of Y is lower than a set threshold value, the controller controls the electric heater to stop heating or continue heating.
Preferably, when Y is greater than 0 and is lower than the threshold value, the controller controls the electric heater to stop heating; if Y <0, then lower than the threshold, the controller controls the electric heater to heat.
The current electric heater is determined to be in a heating state or a non-heating state through sequential pressure size judgment, so that the running state of the electric heater is determined according to different conditions.
Preferably, if Y is 0, heating is judged according to the following:
if P isiIf the arithmetic mean of the first data is larger than the pressure of the first data, the controller controls the electric heater to stop heating when the arithmetic mean of the first data is lower than the threshold; wherein the first data is greater than the pressure of the phase change fluid after the phase change; preferably the pressure at which the phase change fluid substantially changes phase;
if P isiIs less than the pressure of the second data, the controller controls the electric heater to continue heating when the second data is less than or equal to the pressure at which the phase change of the phase-change fluid does not occur.
The first data is pressure data in a fully heated state, and the second data is pressure data in the absence of heating or in the beginning of heating. The judgment of the pressure is also used for determining whether the current electric heater is in a heating state or a non-heating state, so that the operation state of the electric heater is determined according to different conditions.
Preferably, the period of time for measuring the pressure is 1 to 10 minutes, preferably 3 to 6 minutes, and further preferably 4 minutes.
Preferably, the threshold is 100-1000 pa, preferably 500 pa.
Preferably, the pressure value may be an average pressure value over a period of the time period. The pressure at a certain moment in time may also be used. For example, preferably both are pressures at the end of the time period.
Preferably, the pressure detecting element is provided at the free end. Through setting up at the free end, can perceive the pressure variation of free end to realize better control and regulation.
Second, vibration is adjusted automatically based on temperature
Preferably, a temperature detection element is arranged in the heat exchange component and used for detecting the temperature in the heat exchange component, the temperature detection element is in data connection with the controller, the controller obtains the liquid level difference or the accumulation of the change of the liquid level difference according to the liquid level data extracted by the time sequence and through the comparison of the liquid level data in adjacent time periods, and when the liquid level difference or the liquid level difference is lower than a threshold value, the controller controls the electric heater to stop heating or continue heating.
Through the liquid level difference of the front time and the back time or the accumulated liquid level difference detected by the liquid level sensing element, the evaporation of the internal fluid can be judged to be basically saturated through the liquid level difference, and the volume of the internal fluid is basically not changed greatly. So that the fluid undergoes volume reduction to thereby realize vibration. When the liquid level difference rises to a certain degree, the internal fluid starts to enter a stable state again, and at the moment, the fluid needs to be heated so as to be evaporated and expanded again, so that the electric heater needs to be started for heating.
The stable state of the fluid is judged according to the liquid level difference or the accumulation of the change of the liquid level difference, so that the result is more accurate, and the problem of error increase caused by aging due to the problem of operation time is solved.
Preferably, if the liquid level of the previous period is L1, and the liquid level of the adjacent subsequent period is L2, if L1> L2, the controller controls the electric heater to stop heating when the liquid level is lower than the threshold value; if L1< L2, then below the threshold, the controller controls the electric heater to heat.
The current electric heater is determined to be in a heating state or a non-heating state through the sequential liquid level judgment, so that the running state of the electric heater is determined according to different conditions.
Preferably, if the liquid level of the preceding period is L1, the liquid level of the adjacent succeeding period is L2, and if L1 is L2, heating is judged according to the following:
if the L1 is less than the liquid level of the first data or the L1 is 0, the controller controls the electric heater to stop heating when the L1 is less than the threshold value; wherein the first data is greater than the liquid level of the phase-change fluid after the phase change; preferably the first data is a level at which the phase change fluid is substantially phase changed;
if L1 is greater than or equal to a level at which no phase change of the phase change fluid occurs, the controller controls the electric heater to continue heating below the threshold value.
The first data is liquid level data of a fully heated state, including liquid level of dry-out, and the second data is liquid level data of no heating or heating beginning. Through the judgment of the liquid level, whether the current electric heater is in a heating state or a non-heating state is also determined, so that the operation state of the electric heater is determined according to different conditions.
Preferably, the number of the liquid level sensing elements is n, and the liquid level L in the current time period is calculated in sequenceiAnd the liquid level L of the previous time periodi-1Difference D ofi＝Li-Li-1And for n liquid level differences DiPerforming arithmetic cumulative summation
When the value of Y is lower than a set threshold value, the controller controls the electric heater to stop heating or continue heating.
Preferably, when Y is greater than 0 and is lower than the threshold value, the controller controls the electric heater to stop heating; if Y <0, then lower than the threshold, the controller controls the electric heater to heat.
The current electric heater is determined to be in a heating state or a non-heating state through the sequential liquid level judgment, so that the running state of the electric heater is determined according to different conditions.
Preferably, if Y is 0, heating is judged according to the following:
if L isiIs less thanIf the liquid level of the first data is 0 or less than the threshold value, the controller controls the electric heater to stop heating; wherein the first data is greater than the liquid level of the phase-change fluid after the phase change; preferably a level at which the phase change fluid is substantially phase-changed;
if L isiIs greater than the level of the second data, and is less than the threshold value, the controller controls the electric heater to continue heating, wherein the second data is less than or equal to the level at which the phase change fluid does not undergo a phase change.
The first data is liquid level data of a fully heated state, including liquid level of dry-out, and the second data is liquid level data of no heating or heating beginning. The judgment of the liquid level also determines whether the current electric heater is in a heating state or a non-heating state, so that the operation state of the electric heater is determined according to different conditions.
Preferably, the period of time for which the measurement is also made is 1 to 10 minutes, preferably 3 to 6 minutes, and further preferably 4 minutes.
Preferably, the threshold is 1-10 mm, preferably 4 mm.
Preferably, the water level value may be an average water level value over a period of the time period. The water position at a certain moment in time may also be used. Such as preferably both water levels at the end of the time period.
Preferably, the temperature detecting element is provided at an upper end disposed in the center tube 8 and/or the left side tube 21 and/or the right side tube 22.
Preferably, the temperature detecting elements are provided at the upper ends of the center tube 8 and the left and right side tubes 21 and 22.
Preferably, the temperature detection element is provided at the free end. Through setting up at the free end, can perceive the temperature variation of free end to realize better control and regulation.
Thirdly, automatically adjusting vibration based on liquid level
Preferably, a liquid level detection element is arranged inside the central tube 8 and used for detecting the liquid level of the fluid in the lower tube box, the liquid level detection element is in data connection with the controller, the controller obtains the liquid level difference or the accumulation of the change of the liquid level difference according to the liquid level data extracted by the time sequence and through the comparison of the liquid level data in adjacent time periods, and when the liquid level difference or the change of the liquid level difference is lower than a threshold value, the controller controls the electric heater to stop heating or continue heating.
Through the liquid level difference of the front time and the back time or the accumulated liquid level difference detected by the liquid level sensing element, the evaporation of the internal fluid can be judged to be basically saturated through the liquid level difference, and the volume of the internal fluid is basically not changed greatly. So that the fluid undergoes volume reduction to thereby realize vibration. When the liquid level difference rises to a certain degree, the internal fluid starts to enter a stable state again, and at the moment, the fluid needs to be heated so as to be evaporated and expanded again, so that the electric heater needs to be started for heating.
The stable state of the fluid is judged according to the liquid level difference or the accumulation of the change of the liquid level difference, so that the result is more accurate, and the problem of error increase caused by aging due to the problem of operation time is solved.
Preferably, if the liquid level of the previous period is L1, and the liquid level of the adjacent subsequent period is L2, if L1> L2, the controller controls the electric heater to stop heating when the liquid level is lower than the threshold value; if L1< L2, then below the threshold, the controller controls the electric heater to heat.
The current electric heater is determined to be in a heating state or a non-heating state through the sequential liquid level judgment, so that the running state of the electric heater is determined according to different conditions.
Preferably, if the liquid level of the preceding period is L1, the liquid level of the adjacent succeeding period is L2, and if L1 is L2, heating is judged according to the following:
if the L1 is less than the liquid level of the first data or the L1 is 0, the controller controls the electric heater to stop heating when the L1 is less than the threshold value; wherein the first data is greater than the liquid level of the phase-change fluid after the phase change; preferably the first data is a level at which the phase change fluid is substantially phase changed;
if L1 is greater than or equal to a level at which no phase change of the phase change fluid occurs, the controller controls the electric heater to continue heating below the threshold value.
The first data is liquid level data of a fully heated state, including liquid level of dry-out, and the second data is liquid level data of no heating or heating beginning. Through the judgment of the liquid level, whether the current electric heater is in a heating state or a non-heating state is also determined, so that the operation state of the electric heater is determined according to different conditions.
Preferably, the number of the liquid level sensing elements is n, and the liquid level L in the current time period is calculated in sequenceiAnd the liquid level Q of the previous time periodi-1Difference D ofi＝Li-Qi-1And for n liquid level differences DiPerforming arithmetic cumulative summation
When the value of Y is lower than a set threshold value, the controller controls the electric heater to stop heating or continue heating.
Preferably, when Y is greater than 0 and is lower than the threshold value, the controller controls the electric heater to stop heating; if Y <0, then lower than the threshold, the controller controls the electric heater to heat.
The current electric heater is determined to be in a heating state or a non-heating state through the sequential liquid level judgment, so that the running state of the electric heater is determined according to different conditions.
Preferably, if Y is 0, heating is judged according to the following:
if L isiIf the arithmetic mean of the first data is less than the liquid level of the first data or 0, the controller controls the electric heater to stop heating when the arithmetic mean of the first data is less than the threshold value; wherein the first data is greater than the liquid level of the phase-change fluid after the phase change; preferably a level at which the phase change fluid is substantially phase-changed;
if L isiIs greater than the level of the second data, and is lower than the threshold value, the controller controls the electric heater to continue heating, wherein the second data is less than or equal to the level at which the phase change fluid does not undergo phase change.
The first data is liquid level data of a fully heated state, including liquid level of dry-out, and the second data is liquid level data of no heating or heating beginning. Through the judgment of the liquid level, whether the current electric heater is in a heating state or a non-heating state is also determined, so that the operation state of the electric heater is determined according to different conditions.
Preferably, the period of time for which the measurement is also made is 1 to 10 minutes, preferably 3 to 6 minutes, and further preferably 4 minutes.
Preferably, the threshold is 1-10 mm, preferably 4 mm.
Preferably, the water level value may be an average water level value over a period of the time period. The water position at a certain moment in time may also be used. Such as preferably both water levels at the end of the time period.
Fourthly, automatically adjusting vibration based on speed
Preferably, a speed detection element is arranged in the free end of the tube bundle and used for detecting the flow speed of fluid in the free end of the tube bundle, the speed detection element is in data connection with the controller, the controller extracts speed data according to a time sequence, the speed difference or the accumulation of the speed difference change is obtained through comparison of the speed data of adjacent time periods, and when the speed difference or the accumulation of the speed difference is lower than a threshold value, the controller controls the electric heater to stop heating or continue heating.
The difference in time velocity or the cumulative velocity difference before and after detection by the velocity sensing element can be used to determine that the evaporation of the fluid inside has substantially reached saturation and that the volume of the fluid inside has not substantially changed, in which case the fluid inside is relatively stable and the tube bundle is less vibratile, and therefore needs to be adjusted to vibrate and stop heating. So that the fluid undergoes volume reduction to thereby realize vibration. When the speed difference is reduced to a certain degree, the internal fluid starts to enter a stable state again, and the fluid needs to be heated to evaporate and expand again, so that the electric heater needs to be started for heating.
The stable state of the fluid is judged according to the speed difference or the accumulation of the speed difference change, so that the result is more accurate, and the problem of error increase caused by aging due to the running time problem is solved.
Preferably, if the speed of the preceding time period is V1 and the speed of the adjacent following time period is V2, the controller controls the electric heater to stop heating if V1< V2, which is lower than the threshold value; if V1> V2, then below the threshold, the controller controls the electric heater to heat.
The current electric heater is determined to be in a heating state or a non-heating state through the judgment of the speed, so that the running state of the electric heater is determined according to different conditions.
Preferably, if the speed of the preceding time period is V1, the speed of the adjacent following time period is V2, and if V1 is V2, heating is judged according to the following:
if the V1 is greater than the speed of the first data, the controller controls the electric heater to stop heating when the V1 is lower than the threshold value; wherein the first data is greater than the speed of the phase change fluid after the phase change; preferably the first data is the speed at which the phase change fluid is substantially phase changed;
below the threshold, the controller controls the electric heater to continue heating if V1 is less than or equal to the velocity of the second data, which is less than or equal to the velocity at which no phase change of the phase-change fluid occurs.
The first data is speed data of a sufficiently heated state, and the second data is speed data of no heating or heating just started. The judgment of the speed is also used for determining whether the current electric heater is in a heating state or a non-heating state, so that the operation state of the electric heater is determined according to different conditions.
Preferably, the number of the speed sensing elements is n, and the speed V of the current time period is calculated in sequenceiAnd a previous time speed Qi-1Difference D ofi＝Vi-Qi-1And for n speed differences DiPerforming arithmetic cumulative summation
When the value of Y is lower than the set threshold value, controlThe controller controls the electric heater to stop heating or continue heating.
Preferably, when Y is greater than 0 and is lower than the threshold value, the controller controls the electric heater to stop heating; if Y <0, then lower than the threshold, the controller controls the electric heater to heat.
The current electric heater is determined to be in a heating state or a non-heating state through the judgment of the speed, so that the running state of the electric heater is determined according to different conditions.
Preferably, if Y is 0, heating is judged according to the following:
if ViIf the arithmetic mean of the first data is higher than the speed of the first data, the controller controls the electric heater to stop heating when the arithmetic mean of the first data is lower than the threshold; wherein the first data is greater than the speed of the phase change fluid after the phase change; preferably the rate at which the phase change fluid changes phase substantially;
if ViIs less than a speed of a second data, which is less than or equal to a speed at which no phase change of the phase-change fluid occurs, below the threshold value.
The first data is speed data of a sufficiently heated state, and the second data is speed data of no heating or heating just started. The judgment of the speed is also used for determining whether the current electric heater is in a heating state or a non-heating state, so that the operation state of the electric heater is determined according to different conditions.
Preferably, the period of time for measuring the speed is 1 to 10 minutes, preferably 3 to 6 minutes, and further preferably 4 minutes.
Preferably, the threshold is 1-3 m/s, preferably 2 m/s.
Preferably, the speed value may be an average pressure value over a period of the time period. The speed at a certain moment in time may also be used. For example, preferably both are speeds at the end of the time period.
Preferably, the heat exchanger comprises a descaling process, and the descaling process is used for heat exchange in the manner described above.
Although the present invention has been described with reference to the preferred embodiments, it is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (2)
1. A shell-and-tube heat exchanger comprises a shell, tube plates are respectively arranged at two ends of the shell, a heat exchange component is arranged in the shell and 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 closed circulation of heating fluid, an electric heater is arranged in the central tube, and the position of the right tube group is the position of the left tube group rotated by 180 degrees along the axis of the central tube; the heat exchanger is characterized in that a pressure detection element is arranged in the heat exchange component and used for detecting the pressure in the heat exchange component, the pressure detection element is in data connection with a controller, the heat exchanger comprises a descaling process, and the controller controls whether the electric heater heats or not according to the detected pressure difference in the descaling process to enable the tube bundle to vibrate;
the controller extracts pressure data according to the time sequence, obtains the pressure difference or the accumulation of the pressure difference change through the comparison of the pressure data of adjacent time periods, and controls the electric heater to stop heating or continue heating when the pressure difference or the accumulation of the pressure difference change is lower than a threshold value;
if the pressure of the previous time period is P1 and the pressure of the adjacent following time period is P2, if P1< P2, then the controller controls the electric heater to stop heating when the pressure is lower than the threshold value; if P1> P2, the controller controls the electric heater to heat when the threshold value is lower.
2. The heat exchanger of claim 1, wherein the tube group is plural, each tube group comprises a plurality of circular arc-shaped annular tubes, ends of the adjacent annular tubes are communicated, the plurality of annular tubes are formed into a serial structure, and ends of the annular tubes are formed into free ends of the annular tubes; the central tube comprises a first tube orifice and a second tube orifice, the first tube orifice is connected with the inlet of the left tube group, the second tube orifice is connected with the inlet of the right tube group, the outlet of the left tube group is connected with the left tube, and the outlet of the right tube group is connected with the right tube; the first and second orifices are disposed on opposite sides of the central tube.
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| US9103603B2 (en) * | 2009-10-28 | 2015-08-11 | Tai-Her Yang | Thermal conductive cylinder installed with U-type core piping and loop piping |
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| US4284134A (en) * | 1978-09-05 | 1981-08-18 | General Atomic Company | Helically coiled tube heat exchanger |
| JP2012229860A (en) * | 2011-04-26 | 2012-11-22 | Tokyo Gas Chemicals Co Ltd | Coupled liquefied natural gas carburetor |
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