CN112113336A - Heat exchanger with variable liquid level - Google Patents
Heat exchanger with variable liquid level Download PDFInfo
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- CN112113336A CN112113336A CN201910540864.5A CN201910540864A CN112113336A CN 112113336 A CN112113336 A CN 112113336A CN 201910540864 A CN201910540864 A CN 201910540864A CN 112113336 A CN112113336 A CN 112113336A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H7/00—Storage heaters, i.e. heaters in which the energy is stored as heat in masses for subsequent release
- F24H7/02—Storage heaters, i.e. heaters in which the energy is stored as heat in masses for subsequent release the released heat being conveyed to a transfer fluid
- F24H7/0208—Storage heaters, i.e. heaters in which the energy is stored as heat in masses for subsequent release the released heat being conveyed to a transfer fluid using electrical energy supply
- F24H7/0233—Storage heaters, i.e. heaters in which the energy is stored as heat in masses for subsequent release the released heat being conveyed to a transfer fluid using electrical energy supply the transfer fluid being water
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H9/00—Details
- F24H9/18—Arrangement or mounting of grates or heating means
- F24H9/1809—Arrangement or mounting of grates or heating means for water heaters
- F24H9/1818—Arrangement or mounting of electric heating means
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H9/00—Details
- F24H9/20—Arrangement or mounting of control or safety devices
- F24H9/2007—Arrangement or mounting of control or safety devices for water heaters
- F24H9/2014—Arrangement or mounting of control or safety devices for water heaters using electrical energy supply
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- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Instantaneous Water Boilers, Portable Hot-Water Supply Apparatuses, And Control Of Portable Hot-Water Supply Apparatuses (AREA)
Abstract
The invention provides a heat exchanger with variable liquid level, which comprises a shell, wherein tube plates are respectively arranged at two ends of the shell, a liquid level detection element is arranged in a lower tube box and used for detecting the liquid level of fluid in the lower tube box, the liquid level detection element is in data connection with a controller, the controller extracts liquid level data according to time sequence and obtains the accumulation of the liquid level difference or the change of the liquid level difference through the comparison of the liquid level data in adjacent time periods, and when the liquid level data is lower than a threshold value, the controller controls an electric heater to stop heating or continue heating. The heat exchanger can judge whether the heat exchanger reaches a stable state or not according to the internal liquid level difference or the accumulated liquid level difference, and then intelligently controls heating according to the internal liquid level difference, so that the internal fluid can realize frequent vibration, and good descaling and heating effects are realized.
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 increasing and the quality requirement of the heat exchanger is higher. 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 exchanger has high reliability and wide adaptability, it still occupies the dominance of the output and the usage, and according to the related statistics, the usage of the shell and tube type heat exchanger in the current industrial device still accounts for about 70% of the usage of all the heat exchangers.
After the shell-and-tube heat exchanger is scaled, the heat exchanger is cleaned in the conventional modes of steam cleaning, back flushing and the like, and the production practice proves that the effect is not good. The end socket of the heat exchanger can only be disassembled, 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 utilize the vibration of the fluid to induce the heat transfer element to realize the heat exchange strengthening, can change the strict prevention of the vibration induction of the fluid in the heat exchanger into the effective utilization of the vibration, greatly improve the convective heat transfer coefficient of the transmission element at low flow speed, inhibit the dirt on the surface of the heat transfer element by utilizing the vibration, reduce the dirt thermal resistance and realize the composite strengthening heat transfer.
In application, it is found that continuous heating can cause the internal fluid to form stability, i.e. the fluid does not flow or has little fluidity, or the flow is stable, so that the vibration performance of the heat exchange tube is greatly weakened, thereby affecting the descaling of the heat exchange tube and the heating efficiency. There is therefore a need for improvements to the above-described heat exchangers. In this regard, we have developed a new shell and tube heat exchanger capable of generating periodic vibration, and have already filed patent applications.
In the prior application, only the data of the temperature pressure liquid level is controlled, and if certain data is reached, the internal heating is considered to be in a sufficient state, and the fluid flowing state also enters a stable state, but the judgment mode has obvious errors along with the continuous operation of a heating device, so that the result is inaccurate.
Disclosure of Invention
The invention provides a novel shell-and-tube heat exchanger capable of intelligently controlling vibration for overcoming the defects in the prior art, and the shell-and-tube heat exchanger can realize frequent vibration of a heat exchange tube and improve the heating efficiency, thereby realizing good descaling and heating effects.
In order to achieve the purpose, the invention adopts the following technical scheme:
a heat exchanger with variable liquid level comprises a shell, wherein tube plates are arranged at two ends of the shell respectively, a heat exchange component is arranged in the shell and comprises a lower tube box, an upper tube box and a heat exchange tube, the heat exchange tube is communicated with the lower tube box and the upper tube box to form closed circulation of heating fluid, two ends of the lower tube box and the upper tube box are arranged in open holes of the tube plates, and an electric heater is arranged in the lower tube box; filling phase-change fluid in the lower channel box; the heat exchange tubes are one or more, each heat exchange tube comprises a plurality of arc-shaped tube bundles, the central lines of the arc-shaped tube bundles are arcs with the lower tube boxes as concentric circles, and the end parts of the adjacent tube bundles are communicated, so that the end parts of the tube bundles form free ends of the tube bundles,
the liquid level detection element is arranged in the lower tube box and used for detecting the liquid level of fluid in the lower tube box, the liquid level detection element is in data connection with the controller, the controller extracts liquid level data according to the time sequence, the liquid level difference or the accumulation of the change of the liquid level difference is obtained through comparison of the liquid level data in adjacent time periods, and when the liquid level data is lower than a threshold value, the controller controls the electric heater to stop heating or continue heating.
Preferably, if the liquid level of the previous period is L1, and the liquid level of the adjacent following period is L2, if L1> L2, the controller controls the electric heater to stop heating when the threshold value is lower; if L1< L2, then below the threshold, the controller controls the electric heater to heat.
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 the level of the second data, which is less than or equal to the level at which the phase change fluid does not undergo a phase change, then below the threshold, the controller controls the electric heater to continue heating.
Preferably, the liquid level sensing element isn, sequentially calculating the liquid level L of the current time periodiAnd 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 >0 is less than the threshold, 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.
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.
Preferably, the period of time for measuring the liquid level is 1 to 10 minutes, preferably 3 to 6 minutes, and further preferably 4 minutes.
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.
The invention has the following advantages:
1. the heat exchanger can judge whether the heat exchanger reaches a stable state or not according to the internal liquid level difference or the accumulated liquid level difference, and then intelligently controls heating according to the internal liquid level difference, so that the internal fluid can realize frequent vibration, and good descaling and heating effects are realized.
2. The invention designs a layout of a heat exchange component with a novel structure in the shell, and can further improve the heating efficiency.
3. The invention optimizes the optimal relation of the parameters of the heat exchange tube through a large amount of experiments and numerical simulation, thereby realizing the optimal heating efficiency.
4. Through the flowing direction of fluid in the shell, the reasonable change of the internal diameter and the interval of the tube bundle of the heat exchange tube improves the heat exchange efficiency.
Description of the drawings:
FIG. 1 is a top view of a heat exchange member of the present invention.
Fig. 2 is a front view of the heat exchange part.
Fig. 3 is a layout diagram of heat exchange components arranged in a circular shell.
Fig. 4 is a schematic view of the structure of a heat exchange tube.
Fig. 5 is a schematic view of the housing structure.
FIG. 6 is a schematic of a pressure controlled descaling flow.
In the figure: 1. the heat exchange tube comprises a heat exchange tube 2, a lower tube box 3, a free end 4, a free end 5, a shell pass inlet connecting tube 6, a shell pass outlet connecting tube 7, a free end 8, an upper tube box 9, a connecting point 10, a heat exchange part 11, a shell, a tube bundle 12, an electric heater 13, a front tube plate 14, a support 15, a support 16, a rear tube plate 17 and end parts 18-20
Detailed Description
A shell-and-tube heat exchanger, as shown in fig. 5, the shell-and-tube heat exchanger includes a shell 11, a heat exchange component 10, a shell-side inlet connection pipe 5, and a shell-side outlet connection pipe 6; the heat exchange component 10 is arranged in the shell 11 and fixedly connected to the front tube plate 14 and the rear tube plate 17; the shell side inlet connecting pipe 5 and the shell side outlet connecting pipe 6 are both arranged on the shell 11; fluid enters from a shell side inlet connecting pipe 5, exchanges heat through a heat exchange part and exits from a shell side outlet connecting pipe 6.
The end parts 18-20 at both ends of the lower and upper tube boxes are arranged in the openings of the front and rear tube plates 14, 17 for fixation.
Fig. 1 shows a top view of a heat exchange part 10, as shown in fig. 1, the heat exchange part 10 includes a lower tube box 2, an upper tube box 8 and a heat exchange tube 1, the heat exchange tube 1 is communicated with the lower tube box 2 and the upper tube box 8, a fluid is circulated in the lower tube box 2, the upper tube box 8 and the heat exchange tube 1 in a closed manner, an electric heater 13 is disposed in the heat exchange part 10, the electric heater 13 is used for heating the fluid in the heat exchange part 10, and then the fluid in the shell is heated by the heated fluid.
As shown in fig. 1-2, an electric heater 13 is provided in the lower header tank 2; the lower tube box 2 is filled with phase-change fluid; the heat exchange tubes 1 are one or more, each heat exchange tube 1 comprises a plurality of circular arc-shaped tube bundles 12, the central lines of the circular arc-shaped tube bundles 12 are circular arcs which are concentric with the lower tube box 2, the end parts of the adjacent tube bundles 12 are communicated, and fluid forms serial flow between the lower tube box 2 and the upper tube box 8, so that the end parts of the tube bundles form tube bundle free ends 3 and 4; the fluid is phase-change fluid or vapor-liquid phase-change fluid, the heat exchange component is in data connection with the controller, and the controller controls the heating power of the heat exchange component to periodically change along with the change of time.
Preferably, the lower header 2 and the upper header 8 are provided along the length of the shell side. The shell side preferably extends in the horizontal direction.
It has been found in research and practice that the continuous heating of the electric heater with stable power can lead to the stability of the fluid of the internal heat exchange component, i.e. the fluid does not flow or has little fluidity, or the flow is stable, and the vibration performance of the heat exchange tube 1 is greatly weakened, thereby affecting the descaling of the heat exchange tube 1 and the heating efficiency. Therefore, the following improvements are required for the above-mentioned electric heating heat exchange pipe.
In the prior application of the inventor, a periodic heating mode is provided, and the vibration of the heat exchange pipe is continuously promoted through the periodic heating mode, so that the heating efficiency and the descaling effect are improved. However, adjusting the vibration of the tube bundle with a fixed periodic variation can lead to hysteresis and too long or too short a period. Therefore, the invention improves the previous application and intelligently controls the vibration, so that the fluid in the fluid can realize frequent vibration, thereby realizing good descaling and heating effects.
Aiming at the defects in the technology researched in the prior art, the invention provides a novel electric heating water heater capable of intelligently controlling vibration. This water heater can improve heating efficiency to realize fine scale removal and heating effect.
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 pressure difference changes, and when the pressure difference or the accumulation of pressure difference changes 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 much. The fluid is made to undergo 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 steady 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 operation 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 being 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 period is P1, the pressure of the adjacent succeeding 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 of a sufficiently heated state, and the second data is pressure data of no heating or pressure data of 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 sensing element is arranged within the first header tank 2 and/or the second header tank 8.
Preferably, the pressure sensing elements are disposed within the first and second header tanks 2 and 8. The average of the pressures of the two headers can be selected as regulating data.
Preferably, the pressure sensing element is disposed at the free end. Through setting up at the free end, can perceive the pressure change 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 pressure is lower than the threshold value, wherein 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 of a sufficiently heated state, and the second data is pressure data of no heating or pressure data of 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 change of free end to realize better control and regulation.
Independently adjusting vibration 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 fluid inside can be judged to be basically saturated through the liquid level 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 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 following period is L2, if L1> L2, the controller controls the electric heater to stop heating when the threshold value is lower; 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 the level of the second data, which is less than or equal to the level at which the phase change fluid does not undergo a phase change, then below the threshold, the controller controls the electric heater to continue heating.
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 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 the phase-change fluid being substantially phase-changedLiquid level;
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 during which the measurement is also carried out 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 sensing element is provided at an upper end in the lower and/or upper header.
Preferably, the temperature detection element is provided at an upper end in the lower and upper headers.
Preferably, the temperature detection element is provided at the free end. Through setting up at the free end, can perceive the temperature change 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 in the lower pipe box and used for detecting the liquid level of fluid in the lower pipe box, the liquid level detection element is in data connection with the controller, the controller extracts liquid level data according to time sequence and obtains the accumulation of liquid level difference or liquid level difference change through comparison of liquid level data in adjacent time periods, and when the liquid level data 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 fluid inside can be judged to be basically saturated through the liquid level 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 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 following period is L2, if L1> L2, the controller controls the electric heater to stop heating when the threshold value is lower; 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 the level of the second data, which is less than or equal to the level at which the phase change fluid does not undergo a phase change, then below the threshold, the controller controls the electric heater to continue heating.
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 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 during which the measurement is also carried out 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 the detection by the velocity sensing element can be used to determine that the evaporation of the fluid inside has substantially reached saturation and the volume of the fluid inside has not substantially changed, in which case the fluid inside is relatively stable and the tube bundle has poor vibration, 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 steady 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 period is V1 and the speed of the adjacent following period is V2, the controller controls the electric heater to stop heating if V1< V2, below the threshold; 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 succeeding 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 situations.
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 velocity Vi-1Difference D ofi＝Vi-Vi-1And for n speed 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 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 the phase change of the phase-change fluid does not occur, the controller controls the electric heater to continue heating when the speed is less than a 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 situations.
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 pipe diameter of the lower pipe box 2 is smaller than that of the upper pipe box 8, and the pipe diameter of the lower pipe box 2 is 0.5-0.8 times of that of the upper pipe box 8. Through the pipe diameter change of lower tube case and upper tube case, can guarantee that the fluid carries out the phase transition and in the internal time of first box short, get into the heat exchange tube fast, fully get into the heat transfer of second box.
Preferably, the connection position 9 of the heat exchange tube at the lower tube box is lower than the connection position of the upper tube box and the heat exchange tube. Thus, steam can quickly enter the upper pipe box upwards.
Preferably, a return line is provided between the lower and upper headers, optionally at the ends 18-20 of the lower and upper headers, to ensure that condensed fluid in the upper header can enter the first line.
Preferably, the lower tube box and the upper tube box are arranged in the horizontal direction, the plurality of heat exchange tubes are arranged along the flowing direction of fluid in the shell side, and the tube diameter of the heat exchange tube bundle is continuously increased along the flowing direction of the fluid.
Preferably, the tube diameter of the heat exchange tube bundle is increased along the flowing direction of the fluid.
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 heat exchange tubes are arranged in a plurality along the flowing direction of fluid in the shell side, and the distance between every two adjacent heat exchange tubes is gradually reduced along the flowing direction of the fluid.
Preferably, the interval between the heat exchange tubes becomes smaller and larger along the height direction of the lower header.
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 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, as shown in fig. 3, the casing is a casing with a circular cross section, and a plurality of heat exchange components are arranged in the casing.
Preferably, as shown in fig. 3, a plurality of heat exchange members are disposed in the housing, one of which is disposed in the center of the housing to become a central heat exchange member, and the others are distributed around the center of the housing to become peripheral heat exchange members. Through the structural design, the fluid in the shell can fully achieve the vibration purpose, and the heat exchange effect is improved.
Preferably, the heating power of the single peripheral heat exchange member is smaller than the heating power of the central heat exchange member. Through the design, the center reaches higher vibration frequency, a central vibration source is formed, the periphery is influenced, and better heat transfer enhancement and descaling effects are achieved.
Preferably, on the same horizontal heat exchange section, the fluid needs to achieve uniform vibration, and uneven heat exchange distribution is avoided. It is therefore necessary to distribute the amount of heating power among the different heat exchange members reasonably. Experiments show that the heating power ratio of the central heat exchange component to the peripheral tube bundle heat exchange component is related to two key factors, wherein one of the two key factors is related to the distance between the peripheral heat exchange component and the center of the shell (namely the distance between the circle center of the peripheral heat exchange component and the circle center of the central heat exchange component) and the diameter of the shell. Therefore, the invention optimizes the optimal proportional distribution of the pulsating flow according to a large number of numerical simulations and experiments.
Preferably, the radius of the inner wall of the shell is R, the center of the central heat exchange component is arranged at the center of the circular cross section of the shell, the distance from the center of the outer heat exchange component to the center of the circular cross section of the shell is S, the centers of adjacent outer heat exchange components are respectively connected with the center of the circular cross section, the included angle formed by the two connecting lines is a, the heating power of the outer heat exchange component is P2, and the heating power of a single central heat exchange component is P1, so that the following requirements are met:
P1/P2 ═ a-b ═ Ln (R/S); ln is a logarithmic function;
a, b are coefficients, wherein 2.0869< a <2.0875,0.6833< b < 0.6837;
preferably, 1.35< R/S < 2.1; further preferred is 1.4< R/S < 2.0;
preferably, 1.55< P1/P2< 1.9. Further preferred is 1.6< P1/P2< 1.8;
wherein 35 ° < a <80 °.
Preferably, the number of the four-side distribution is 4-5.
Preferably, R is 1600-2400 mm, preferably 2000 mm; s is 1150-1700 mm, preferably 1300 mm; the diameter of the heat exchange tube bundle is 12-20 mm, preferably 16 mm; the outermost diameter of the heat exchange tube is preferably 300-560 mm, preferably 400 mm. The tube diameter of the lower manifold is 100-116 mm, preferably 108 mm, and the length of the upper manifold and the lower manifold is 1.8-2.2 m.
The total heating power is preferably 5000-.
More preferably, a is 2.0872 and b is 0.6835.
Preferably, the box body is of a circular section, and is provided with a plurality of heat exchange components, wherein one heat exchange component is arranged at the center of the circle of the circular section, and the other heat exchange components are distributed around the center of the circle of the circular section. The heat exchange tubes 1 are in one group or multiple groups, each group of heat exchange tubes 1 comprises a plurality of circular arc-shaped tube bundles 12, the central lines of the circular arc-shaped tube bundles 12 are circular arcs of concentric circles, and the end parts of the adjacent tube bundles 12 are communicated, so that the end parts of the heat exchange tubes 1 form free ends 3 and 4 of the tube bundles, such as the free ends 3 and 4 in fig. 2.
Preferably, the heating fluid is a vapor-liquid phase-change fluid.
Preferably, the lower header 2, the upper header 8 and the heat exchange tubes 1 are all of a circular tube structure.
Preferably, the tube bundle of the heat exchange tubes 1 is an elastic tube bundle.
The heat exchange coefficient can be further improved by arranging the tube bundle of the heat exchange tube 1 with an elastic tube bundle.
Preferably, the concentric circles are circles centered around the center of the lower header 2. I.e., the tube bundle 12 of heat exchange tubes 1 is arranged around the center line of the lower header 2.
As shown in fig. 4, the tube bundle 12 is not a complete circle, but rather leaves a mouth, thereby forming the free end of the tube bundle. The angle of the arc of the mouth part is 65-85 degrees, namely the sum of included angles b and c in figure 4 is 65-85 degrees.
Preferably, the ends of the tube bundle on the same side are aligned in the same plane, with the extension of the ends (or the plane in which the ends lie) passing through the median line of the lower header 2.
Further preferably, the electric heater 13 is an electric heating rod.
Preferably, the first end of the inner tube bundle of the heat exchange tube 1 is connected with the lower tube box 2, the second end is connected with one end of the adjacent outer tube bundle, one end of the outermost tube bundle of the heat exchange tube 1 is connected with the upper tube box 8, and the end parts of the adjacent tube bundles are communicated, so that a series structure is formed.
The included angle c formed by the plane of the first end and the plane of the central lines of the lower pipe box 2 and the upper pipe box 8 is 40-50 degrees.
The included angle b formed by the plane of the second end and the plane of the central lines of the lower pipe box 2 and the upper pipe box 8 is 25-35 degrees.
Through the design of the preferable included angle, the vibration of the free end is optimal, and therefore the heating efficiency is optimal.
As shown in fig. 4, the number of tube bundles of heat exchange tube 1 is 4, and tube bundles A, B, C, D are communicated. Of course, the number is not limited to four, and a plurality of the connecting structures are provided as required, and the specific connecting structure is the same as that of fig. 4.
The heat exchange tubes 1 are multiple, the heat exchange tubes 1 are respectively and independently connected with the lower tube box 2 and the upper tube box 8, and the heat exchange tubes 1 are in parallel connection.
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 heat exchanger with variable liquid level comprises a shell, wherein tube plates are arranged at two ends of the shell respectively, a heat replacement part is arranged in the shell and comprises a lower tube box, an upper tube box and a heat exchange tube, the heat exchange tube is communicated with the lower tube box and the upper tube box to form closed circulation of heating fluid, two ends of the lower tube box and the upper tube box are arranged in openings of the tube plates, and an electric heater is arranged in the lower tube box; filling phase-change fluid in the lower channel box; the heat exchange tubes are one or more, each heat exchange tube comprises a plurality of arc-shaped tube bundles, the central lines of the arc-shaped tube bundles are arcs with the lower tube boxes as concentric circles, and the end parts of the adjacent tube bundles are communicated, so that the end parts of the tube bundles form free ends of the tube bundles,
a liquid level detection element is arranged in the lower tube box and used for detecting the liquid level of fluid in the lower tube box, the liquid level detection element is in data connection with the controller, the controller extracts liquid level data according to a time sequence and obtains the accumulation of liquid level difference or liquid level difference change through comparison of liquid level data of adjacent time periods, and when the liquid level data is lower than a threshold value, the controller controls the electric heater to stop heating or continue heating;
if the liquid level of the previous time period is L1, the liquid level of the adjacent subsequent time period is L2, and 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.
2. The heat exchanger comprises tube plates arranged at two ends of the shell respectively, a heat replacement part is arranged in the shell, the heat exchange part comprises a lower tube box, an upper tube box and a heat exchange tube, and the heat exchange tube is communicated with the lower tube box and the upper tube box to form closed circulation of heating fluid.
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Application publication date: 20201222 |