Scaling monitoring system for low-temperature multi-effect distillation seawater desalination heat exchange tube

Abstract

The invention relates to a scaling monitoring system for a low-temperature multi-effect distillation seawater desalination heat exchange tube, which belongs to the technical field of seawater desalination and comprises a low-temperature multi-effect distillation seawater desalination evaporator, a detection element, a data transmission module, a data receiving module and a data analysis module. The detection element and data transmission module comprises a heat exchange tube inner steam temperature measurement thermal resistor, a heat exchange tube inner wall temperature measurement thermal resistor, a heat exchange tube outer seawater temperature measurement thermal resistor and a data transmission module electrically connected with the heat exchange tube inner steam temperature measurement thermal resistor, the heat exchange tube inner wall temperature measurement thermal resistor and the heat exchange tube outer seawater temperature measurement thermal resistor. The real-time distribution condition of scaling in the evaporator can be obtained through the detection elements arranged at different positions, so that operation adjustment is guided, and the heat exchange efficiency and the water yield are improved; the scaling distribution condition can accurately guide maintenance and chemical cleaning operation.

Description

Technical Field

[0001] The invention belongs to the technical field of seawater desalination, and in particular relates to a low-temperature multi-effect distillation seawater desalination heat exchange tube scaling monitoring system. Background Art

[0002] Low-temperature multi-effect distillation desalination technology has the advantages of low pretreatment requirements, good water quality, large load adjustment range, and simple operation and maintenance, and has become the mainstream technology for thermal desalination. During the normal operation of the low-temperature multi-effect distillation desalination device, due to the evaporation and concentration of seawater outside the heat exchange tube, a scale layer will gradually form on the surface of the heat exchange tube. If the operation is improper, such as too low spraying seawater volume, uneven spraying, insufficient dosage of scale inhibitor, etc., it may cause scaling to intensify and quickly form a large amount of scale layer, seriously affecting the heat exchange efficiency and water production.

[0003] At present, the judgment of scaling of low-temperature multi-effect distillation desalination equipment is based on the decrease of water production and the increase of apparent heat exchange temperature difference, but the two are not absolutely correlated. Water production and temperature difference may also be affected by input heat, external operating conditions, etc., and cannot accurately reflect the scaling situation. In addition, the current method can only make an estimate of the overall scaling of the evaporator, but cannot judge the scaling degree of each effect and different parts of the heat exchange tube bundle.

[0004] As the water industry continues to integrate emerging intelligent industrial technologies and presents a new trend towards intelligent water development, refined real-time monitoring and feedback of scaling in low-temperature multi-effect distillation desalination devices are of great significance to the intelligent development of thermal desalination. Summary of the invention

[0005] The technical problem to be solved by the present invention is to design a heat exchange tube scaling monitoring system for a low-temperature multi-effect distillation seawater desalination device, which can reflect the scaling degree of different effects and different heat exchange tube bundles of the evaporator in real time, thereby guiding the adjustment of the operation and optimizing the operation.

[0006] In order to achieve the above-mentioned purpose, the technical solution of the present invention provides a low-temperature multi-effect distillation seawater desalination heat exchange tube scaling monitoring system, comprising a low-temperature multi-effect distillation seawater desalination evaporator, a detection element and a data transmission module arranged on the low-temperature multi-effect distillation seawater desalination evaporator, a data receiving module connected to the detection element and the data transmission module by signal, and a data analysis module connected to the data receiving module by signal; the detection element and the data transmission module include a steam temperature measuring thermal resistor inside the heat exchange tube, a heat exchange tube inner wall temperature measuring thermal resistor, and a seawater temperature measuring thermal resistor outside the heat exchange tube arranged on the low-temperature multi-effect distillation seawater desalination evaporator, and a data transmission module electrically connected to the steam temperature measuring thermal resistor inside the heat exchange tube, the heat exchange tube inner wall temperature measuring thermal resistor, and the seawater temperature measuring thermal resistor outside the heat exchange tube.

[0007] Preferably, the low-temperature multi-effect distillation seawater desalination evaporator comprises a first-effect heat exchange tube bundle, an intermediate-effect heat exchange tube bundle and a final-effect heat exchange tube bundle, and the first-effect heat exchange tube bundle, the intermediate-effect heat exchange tube bundle and the final-effect heat exchange tube bundle are all provided with the detection element and the data transmission module.

[0008] Preferably, the same low-temperature multi-effect distillation seawater desalination evaporator is provided with a plurality of different intermediate effect heat exchange tube bundles.

[0009] Preferably, the data transmission module wirelessly transmits the detection data of the detection element to the data receiving module via radio frequency and / or WiFi.

[0010] Preferably, the data receiving module receives the detection data and transmits it to the data analyzing module.

[0011] Preferably, the data analysis module displays and analyzes the received detection data in real time.

[0012] Preferably, the data analysis module calculates the ratio of the difference between the steam temperature in the heat exchange tube and the inner wall temperature of the heat exchange tube to the difference between the inner wall temperature of the heat exchange tube and the seawater temperature outside the heat exchange tube based on the received data, and the ratio is used to reflect the degree of scaling at the heat exchange tube bundle where the detection element is located.

[0013] Preferably, a plurality of the detection elements and data transmission modules are arranged at different locations of the first-effect heat exchange tube bundle, the intermediate-effect heat exchange tube bundle and the final-effect heat exchange tube bundle to monitor the scaling degree of different heat exchange tube bundle locations of different effects in real time.

[0014] Preferably, according to the heat transfer principle, the heat flux density in the heat transfer process follows the following relationship:

[0015]

[0016] Transformed to get,

[0017]

[0018] Among them, R1, R2 and r are the thermal resistances of the hot side, cold side and pipe wall respectively.

[0019]

[0020] Where α1 and α2 are the hot side condensation heat transfer coefficient and the cold side evaporation heat transfer coefficient, respectively, and r1 and r2 are the hot side and cold side fouling thermal resistances, respectively.

[0021] A low-temperature multi-effect distillation seawater desalination heat exchange tube scaling monitoring system provided by the present invention has the following advantages: the ratio γ of the temperature difference between the inside and outside of the heat exchange tube and the tube wall temperature can accurately reflect the scale thermal resistance of the heat exchange tube wall, thereby reflecting the scaling degree; the real-time distribution of scaling in the evaporator can be obtained by arranging detection elements at different positions, thereby guiding operation adjustment and improving heat exchange efficiency and water production; the scaling distribution can also accurately guide maintenance and chemical cleaning operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the scaling monitoring system for heat exchange tubes of low-temperature multi-effect distillation seawater desalination of the present invention;

[0023] Figure 2 It is a schematic diagram of detection elements and data transmission modules in the low-temperature multi-effect distillation seawater desalination heat exchange tube scaling monitoring system of the present invention.

[0024] Figure numerals: 1. Low-temperature multi-effect distillation desalination evaporator; 11. First-effect heat exchange tube bundle; 12. Intermediate-effect heat exchange tube bundle; 13. Final-effect heat exchange tube bundle; 2. Detection element and data transmission module; 21. Data transmission module; 22. Steam temperature measuring thermal resistor in heat exchange tube; 23. Temperature measuring thermal resistor on inner wall of heat exchange tube; 24. Seawater temperature measuring thermal resistor outside heat exchange tube; 3. Data receiving module; 4. Data analysis module. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] The embodiment of the present invention discloses a low-temperature multi-effect distillation seawater desalination heat exchange tube scaling monitoring system, comprising a low-temperature multi-effect distillation seawater desalination evaporator 1, a detection element and data transmission module 2, a data receiving module 3 and a data analysis module 4; the low-temperature multi-effect distillation seawater desalination evaporator 1 comprises a first-effect heat exchange tube bundle 11, an intermediate-effect heat exchange tube bundle 12 and a final-effect heat exchange tube bundle 13, and the intermediate-effect heat exchange tube bundle 12 may include several different intermediate-effect heat exchange tube bundles 12 according to actual design. The detection element and data transmission module 2 comprises a data transmission module 21 and a detection element, and the detection element comprises three integrated thermal resistors.

[0027] Multiple detection elements and data transmission modules 2 are arranged at different parts of the first effect heat exchange tube bundle 11, the intermediate effect heat exchange tube bundle 12 and the final effect heat exchange tube bundle 13, so as to monitor the scaling degree of different heat exchange tube bundle parts of different effects in real time. Furthermore, multiple detection elements are arranged at different heat exchange tube bundle parts of different effects of the low-temperature multiple-effect distillation device, so as to monitor the scaling degree of different heat exchange tube bundle parts of different effects in real time.

[0028] The three thermal resistors of the detection element are respectively a thermal resistor 22 for measuring the temperature of steam in the heat exchange tube, a thermal resistor 23 for measuring the temperature of the inner wall of the heat exchange tube, and a thermal resistor 24 for measuring the temperature of seawater outside the heat exchange tube, which respectively detect the steam temperature T in the heat exchange tube, the inner wall temperature Tw of the heat exchange tube, and the seawater temperature t outside the heat exchange tube.

[0029] The data transmission module 21 can wirelessly transmit the detection data of the detection element through radio frequency, WiFi, etc., and after being received by the data receiving module 3, the data analysis module 4 will display and analyze it in real time.

[0030] The data analysis module 4 calculates the ratio γ of the difference between the steam temperature in the heat exchange tube and the inner wall temperature of the heat exchange tube (T-Tw) to the difference between the inner wall temperature of the heat exchange tube and the seawater temperature outside the heat exchange tube (Tw-t) based on the received data. This ratio can effectively reflect the degree of scaling at the heat exchange tube bundle where the detection element is located.

[0031] The present invention accurately reflects the fouling thermal resistance of the heat exchange tube wall through the ratio of the temperature inside and outside the heat exchange tube to the temperature difference of the tube wall, thereby reflecting the degree of scaling. The real-time distribution of scaling in the evaporator can be obtained by arranging detection elements at different positions, thereby guiding operation adjustment and improving heat exchange efficiency and water production. The scaling distribution can also accurately guide maintenance and chemical cleaning operations.

[0032] Specifically, Figure 1 A schematic diagram of a low-temperature multi-effect distillation seawater desalination heat exchange tube scaling monitoring system provided in this embodiment, the system includes a low-temperature multi-effect distillation seawater desalination evaporator 1, a detection element and data transmission module 2, a data receiving module 3 and a data analysis module 4; the low-temperature multi-effect distillation seawater desalination evaporator 1 includes a first-effect heat exchange tube bundle 11, an intermediate-effect heat exchange tube bundle 12 and a final-effect heat exchange tube bundle 13, and the intermediate-effect heat exchange tube bundle 12 may include several different intermediate-effect heat exchange tube bundles 12 according to actual design.

[0033] The detection element and data transmission module 2 includes a data transmission module 21 and three thermal resistors, namely a thermal resistor 22 for measuring the temperature of steam in the heat exchange tube, a thermal resistor 23 for measuring the temperature of the inner wall of the heat exchange tube, and a thermal resistor 24 for measuring the temperature of seawater outside the heat exchange tube.

[0034] The data transmission module 21 wirelessly transmits the detection data of the detection element through radio frequency, WiFi, etc., and after being received by the data receiving module 3, the data is displayed and analyzed in real time in the data analysis module 4.

[0035] The data analysis module 4 calculates the ratio γ of the difference between the steam temperature in the heat exchange tube and the inner wall temperature of the heat exchange tube (T-Tw) to the difference between the inner wall temperature of the heat exchange tube and the seawater temperature outside the heat exchange tube (Tw-t) based on the received data. This ratio can effectively reflect the degree of scaling at the heat exchange tube bundle where the detection element is located.

[0036] Multiple detection elements and data transmission modules 2 are arranged at different locations of the first-effect heat exchange tube bundle 11, the intermediate-effect heat exchange tube bundle 12 and the final-effect heat exchange tube bundle 13, and can monitor the scaling degree of different heat exchange tube bundles of different effects in real time.

[0037] According to the heat transfer principle, the heat flux density in the heat transfer process follows the following relationship:

[0038]

[0039] Transformed to get,

[0040]

[0041] Among them, R1, R2 and r are the thermal resistances of the hot side, cold side and pipe wall respectively.

[0042]

[0043] Where α1 and α2 are the hot side condensation heat transfer coefficient and the cold side evaporation heat transfer coefficient, respectively, and r1 and r2 are the hot side and cold side fouling thermal resistances, respectively.

[0044] In the operating range of low-temperature multi-effect distillation seawater desalination, the condensation heat transfer coefficient α1 and the evaporation heat transfer coefficient α2 change little with the operating conditions and can be approximated as fixed values; the steam side fouling thermal resistance r1 is very small and can be ignored; the pipe wall thermal resistance r is a fixed value. Therefore, the change of the seawater side fouling thermal resistance r2 will be directly reflected in the temperature difference ratio γ.

[0045] Taking the typical low-temperature multi-effect distillation desalination as an example, α1 is 8000W / (m2℃), α2 is 6000W / (m2℃), and r is 2.6×10 -5 m2℃ / W, then

[0046]

[0047] For a new clean heat exchange tube, r2 = 0, at this time, γ = 0.749; when the heat exchange tube is scaled, it is assumed that the fouling thermal resistance is r2 = 9 × 10 -5m2℃ / W, at this time, γ=0.486. It can be seen that γ changes significantly with the fouling thermal resistance, which can accurately reflect the fouling situation.

[0048] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A low-temperature multi-effect distillation seawater desalination heat exchange tube scaling monitoring system, characterized in that: The invention comprises a low-temperature multi-effect distillation seawater desalination evaporator (1), a detection element and a data transmission module (2) arranged on the low-temperature multi-effect distillation seawater desalination evaporator (1), a data receiving module (3) connected to the detection element and the data transmission module (2) by signals, and a data analysis module (4) connected to the data receiving module (3) by signals; the detection element and the data transmission module (2) comprise a steam temperature measuring thermal resistor (22) inside a heat exchange tube, a heat exchange tube inner wall temperature measuring thermal resistor (23), and a seawater temperature measuring thermal resistor (24) outside the heat exchange tube, which are arranged on the low-temperature multi-effect distillation seawater desalination evaporator (1), and a data transmission module (21) electrically connected to the steam temperature measuring thermal resistor (22) inside the heat exchange tube, the heat exchange tube inner wall temperature measuring thermal resistor (23), and the seawater temperature measuring thermal resistor (24) outside the heat exchange tube.

2. A low-temperature multi-effect distillation seawater desalination heat exchange tube scaling monitoring system according to claim 1, characterized in that: The low-temperature multi-effect distillation seawater desalination evaporator (1) comprises a first-effect heat exchange tube bundle (11), an intermediate-effect heat exchange tube bundle (12) and a final-effect heat exchange tube bundle (13); the first-effect heat exchange tube bundle (11), the intermediate-effect heat exchange tube bundle (12) and the final-effect heat exchange tube bundle (13) are all provided with the detection element and the data transmission module (2).

3. A low-temperature multi-effect distillation seawater desalination heat exchange tube scaling monitoring system according to claim 2, characterized in that: The same low-temperature multi-effect distillation seawater desalination evaporator (1) is provided with a plurality of different intermediate-effect heat exchange tube bundles (12).

4. A low-temperature multi-effect distillation seawater desalination heat exchange tube scaling monitoring system according to claim 2, characterized in that: The data transmission module (21) wirelessly transmits the detection data of the detection element to the data receiving module (3) via radio frequency and / or WiFi.

5. A low-temperature multi-effect distillation seawater desalination heat exchange tube scaling monitoring system according to claim 4, characterized in that: The data receiving module (3) receives the detection data and transmits it to the data analysis module (4).

6. A low-temperature multi-effect distillation seawater desalination heat exchange tube scaling monitoring system according to claim 5, characterized in that: The data analysis module (4) displays and analyzes the received detection data in real time.

7. A low-temperature multi-effect distillation seawater desalination heat exchange tube scaling monitoring system according to claim 6, characterized in that: The data analysis module (4) calculates the ratio of the difference between the steam temperature in the heat exchange tube and the inner wall temperature of the heat exchange tube to the difference between the inner wall temperature of the heat exchange tube and the seawater temperature outside the heat exchange tube based on the received data. The ratio is used to reflect the scaling degree of the heat exchange tube bundle where the detection element is located.

8. A low-temperature multi-effect distillation seawater desalination heat exchange tube scaling monitoring system according to claim 7, characterized in that: The plurality of detection elements and data transmission modules (2) are arranged at different locations of the first-effect heat exchange tube bundle (11), the intermediate-effect heat exchange tube bundle (12) and the final-effect heat exchange tube bundle (13) to monitor in real time the scaling degree of different heat exchange tube bundle locations of different effects.

9. A low-temperature multi-effect distillation seawater desalination heat exchange tube scaling monitoring system according to claim 8, characterized in that: According to the heat transfer principle, the heat flux density in the heat transfer process follows the following relationship: Transformed to get, Among them, R1, R2 and r are the thermal resistances of the hot side, cold side and pipe wall respectively. Where α1 and α2 are the hot side condensation heat transfer coefficient and the cold side evaporation heat transfer coefficient, respectively, and r1 and r2 are the hot side and cold side fouling thermal resistances, respectively.

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