Salt removal heat exchanger

Abstract

The present application relates to the field of chemical environmental protection technology, and particularly relates to a desalting heat exchanger, which comprises a heat exchanger I section and a heat exchanger II section, the top end of the heat exchanger I section and the top end of the heat exchanger II section are communicated through a connecting section, and the bottom end of the heat exchanger I section and the bottom end of the heat exchanger II section are communicated through a salt discharging pipe; the heat exchanger I section comprises, from inside to outside, a first heat exchange inner tube and a first heat exchange outer tube; the heat exchanger II section comprises, from inside to outside, a second heat exchange inner tube and a second heat exchange outer tube; and the heat exchanger I section and the heat exchanger II section are each independently provided with a molten salt separation device. The total desalting efficiency of the desalting heat exchanger provided by the present application reaches more than 98%, the molten salt can be separated while heat exchange is carried out, the problem of molten salt blockage of subsequent heat exchange equipment and pipelines is solved, and the separation and recycling of salts in waste sulfuric acid are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of chemical environmental protection technology, in particular to a desalination heat exchanger. BACKGROUND

[0002] China is the first country in the production and use of dyes, in recent years, China's dye production and use accounts for more than 70% of the world, dyes and dye intermediates in the production process will produce a large amount of waste sulfuric acid, the above waste sulfuric acid after concentration contains more than 70% sulfuric acid, also contains organic matter and various sulfate and chloride, such as sodium sulfate, potassium sulfate, sodium chloride, potassium chloride, etc., it is extremely difficult to handle. The commonly used treatment methods at home include: neutralization, oxidation, extraction, adsorption, etc., but the above methods all have the disadvantages of low recovery rate, serious secondary pollution, etc., and cannot be completely treated.

[0003] CN106629630A proposes a salt-containing waste sulfuric acid cracking process, which cracks the salt-containing waste sulfuric acid at high temperature, then recovers the waste heat of high-temperature flue gas through a waste heat boiler and an air preheater, and then sends the flue gas into a subsequent acid production system to produce finished sulfuric acid. Since the dye waste acid contains a high concentration of salts, the above salts generate liquid molten salt in the cracking furnace, and the molten salt droplets are entrained into the heat exchange system such as the waste heat boiler and the air preheater with the cracking flue gas. A large amount of molten salt adheres to the heat exchange tube wall and the pipeline to form solid salt, which blocks the waste heat boiler heat exchange tube and also causes the waste heat boiler heat exchange tube to be perforated, thereby causing safety hazards and even device shutdown. SUMMARY

[0004] The purpose of the present application is to overcome the technical problems of high salt content in the cracking flue gas in the prior art, which causes the cracking flue gas to block the pipeline in the heat exchange process, and even causes the device to shut down, and to provide a desalination heat exchanger.

[0005] In order to achieve the above purpose, the present application provides a desalination heat exchanger, which comprises a heat exchanger I section and a heat exchanger II section, the top end of the heat exchanger I section and the top end of the heat exchanger II section are communicated through a connecting section, the bottom end of the heat exchanger I section and the bottom end of the heat exchanger II section are communicated through a salt discharge pipe;

[0006] The heat exchanger I section comprises, from inside to outside, a first heat exchange inner tube and a first heat exchange outer tube, the bottom of the first heat exchange inner tube is provided with a flue gas inlet, the top of the first heat exchange outer tube is provided with a first air outlet, and the bottom of the first heat exchange outer tube is provided with a first air inlet;

[0007] The heat exchanger II section comprises, from inside to outside, a second heat exchange inner tube and a second heat exchange outer tube, the bottom of the second heat exchange inner tube is provided with a flue gas outlet, the top of the second heat exchange outer tube is provided with a second air inlet, and the bottom of the second heat exchange outer tube is provided with a second air outlet;

[0008] The heat exchanger I section and the heat exchanger II section are each independently provided with a molten salt separation device selected from at least one of a grid plate, a honeycomb plate, a corrugated plate and a high-voltage discharge device.

[0009] Through the technical scheme, the desalination heat exchanger can remove liquid salt droplets with a particle size of ≤50 μm while heat exchanging, the total desalination efficiency of the two sections of the desalination heat exchanger reaches 98% or more, the molten salt in the salt-containing flue gas can be sufficiently removed while heat exchanging, the crystallization of the molten salt in the heat exchange process can be avoided, the molten salt plugging problem of subsequent heat exchange equipment and pipelines is solved, the separation and recycling of the salts in the waste sulfuric acid are realized, and the heat exchange efficiency of the salt-containing flue gas is improved. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 is a structural schematic view of a desalination heat exchanger according to an embodiment of the present application;

[0011] Figure 2 is an A-A sectional view of a heat exchanger I section according to an embodiment of the present application;

[0012] Figure 3 is a B-B sectional view of a heat exchanger II section according to an embodiment of the present application.

[0013] REFERENCE SIGNS

[0014] 31, first heat exchange inner tube 32, first heat exchange outer tube 33, first heat preservation layer

[0015] 34, molten salt separation module 35, first spoiler plate 36, flue gas inlet

[0016] 37, front smoke box 38, first air inlet 39, first air outlet

[0017] 310, drainage hole 311, overflow weir 312, salt discharge pipe

[0018] 316, first corrosion-resistant layer 320, first maintenance hole 41, second heat exchange inner tube

[0019] 42, second heat exchange outer tube 43, second heat preservation layer 45, second spoiler plate

[0020] 46, flue gas outlet 47, second air outlet 48, second air inlet

[0021] 410, anode pipe 411, cathode wire 413, rear smoke box

[0022] 420, second maintenance hole 416, second corrosion-resistant layer DETAILED DESCRIPTION

[0023] The specific embodiments of the present application are described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and explanatory and are not intended to limit the present application.

[0024] In the present application, the orientation words such as "upper", "lower", "left", "right" generally refer to the upper, lower, left and right shown in the drawings, and "inner", "outer" generally refer to the inner and outer relative to the contour of each component itself, and "far", "near" generally refer to the far and near relative to the contour of each component itself, unless otherwise specified.

[0025] Figure 1 is a structural schematic diagram of a desalting heat exchanger according to an embodiment of the present application, as shown, the desalting heat exchanger comprises a heat exchanger I section 3 and a heat exchanger II section 4, the top end of the heat exchanger I section 3 and the top end of the heat exchanger II section 4 are communicated through a connecting section 9. Figure 1

[0026] The heat exchanger I section 3 comprises, in order from inside to outside, a first heat exchange inner tube 31 and a first heat exchange outer tube 32, the bottom of the first heat exchange inner tube 31 is provided with a flue gas inlet 36, the top of the first heat exchange outer tube 32 is provided with a first air outlet 39, and the bottom of the first heat exchange outer tube 32 is provided with a first air inlet 38.

[0027] The heat exchanger II section 4 comprises, in order from inside to outside, a second heat exchange inner tube 41 and a second heat exchange outer tube 42, the bottom of the second heat exchange inner tube 41 is provided with a flue gas outlet 46, the top of the second heat exchange outer tube 42 is provided with a second air inlet 48, and the bottom of the second heat exchange outer tube 42 is provided with a second air outlet 47.

[0028] The heat exchanger I section 3 and the heat exchanger II section 4 are each independently provided with a molten salt separation device, and the molten salt separation device is selected from at least one of a grid plate, a honeycomb plate, a corrugated plate and a high-voltage discharge device.

[0029] In some preferred embodiments of the present application, in the heat exchanger I section 3, the salt-containing flue gas passes through the inner tube and the air passes through the outer tube, specifically, the heat exchanger I section 3 comprises, in order from inside to outside, a first heat exchange inner tube 31 and a first heat exchange outer tube 32, the bottom of the first heat exchange inner tube 31 is provided with a flue gas inlet 36, the top of the first heat exchange outer tube 32 is provided with a first air outlet 39, and the bottom of the first heat exchange outer tube 32 is provided with a first air inlet 38, for heat exchange between the salt-containing flue gas and the air to obtain first flue gas, second hot air and liquid molten salt.

[0030] Figure 2 is an A-A sectional view of the heat exchanger I section according to an embodiment of the present application; as shown, Figure 2 ​As shown, in some preferred embodiments of the present application, the first heat exchange inner tube 31 is provided with a molten salt separation module 34, the molten salt separation module 34 comprises a plurality of separation plates arranged axially spaced along the first heat exchange inner tube 31, the separation plates are filled with structured packing or random packing, preferably structured packing; further preferably, the structured packing is selected from at least one of grid plate, honeycomb plate and corrugated plate, most preferably grid plate or honeycomb plate, the molten salt separation module 34 can trap and collect molten salt droplets in the salt-containing flue gas, so that the molten salt droplets are attached to the separation plates and finally drop to the bottom of the first heat exchange inner tube 31.

[0031] In order to balance the heat exchange efficiency and desalination efficiency, preferably, the ratio of the radius of the first heat exchange outer tube 32 to the radius of the first heat exchange inner tube 31 is 1.2:1 to 2:1.

[0032] In order to improve the salt and corrosion resistance of the molten salt separation module 34, the material of the molten salt separation module 34 is preferably a corrosion-resistant material, most preferably silicon carbide ceramic or acid-resistant ceramic.

[0033] In order to improve the heat exchange efficiency of the heat exchanger I section 3, preferably, the heat exchanger I section 3 is further provided with a plurality of first turbulence plates 35 arranged axially spaced therealong, one end of the first turbulence plate 35 is welded to the inner wall of the first heat exchange outer tube 32. Under the above preferred condition, the first turbulence plate 35 can disturb the first air and improve the heat exchange efficiency of the salt-containing flue gas and the first air.

[0034] Under this preferred condition, the heat exchange efficiency of the salt-containing flue gas and the first air can be further improved.

[0035] According to the present application, preferably, the first turbulence plate 35 is semi-annular, under this preferred condition, the heat exchange efficiency of the salt-containing flue gas and the first air can be further improved.

[0036] By providing the molten salt separation module 34 in the first heat exchange inner tube 31, large-size molten salt droplets in the salt-containing flue gas can be captured, and the removal rate of molten salt in the salt-containing flue gas can reach more than 80%.

[0037] The first flue gas, obtained by exchanging heat between the salt-containing flue gas and the first air, enters the second heat exchange inner tube 41 of the heat exchanger section II 4 through the connecting section 9. Specifically, in the heat exchanger section II 4, the flue gas flows through the inner tube and the air flows through the outer tube. More specifically, the heat exchanger section II 4 includes, from the inside to the outside, the following components in sequence: a second heat exchange inner tube 41, a second heat exchange outer tube 42, and a second insulation layer 43. The bottom of the second heat exchange inner tube 41 is provided with a flue gas outlet 46, the top of the second heat exchange outer tube 42 is provided with a second air inlet 48, and the bottom of the second heat exchange outer tube 42 is provided with a second air outlet 47. This is used to exchange heat between the first flue gas and the third air to obtain a second flue gas, a fourth hot air, and molten salt.

[0038] Figure 3 This is a cross-sectional view of heat exchanger section II according to an embodiment of the present invention; as shown Figure 3 As shown, in some preferred embodiments of the present invention, after the salt-containing flue gas undergoes heat exchange and molten salt separation in the first heat exchange inner tube 31, large-diameter molten salt droplets are trapped, while small-diameter molten salt droplets remain entrained in the first flue gas. In order to separate the small-diameter molten salt droplets from the first flue gas, under preferred conditions, the second heat exchange inner tube 41 is provided with several high-voltage discharge devices arranged in parallel along the axial direction. The high-voltage discharge devices can discharge to form an electric field, thereby capturing charged molten salt droplets and improving the molten salt removal efficiency. Under preferred conditions, the high-voltage discharge device includes an anode tube 410 and a cathode wire 411 disposed in the anode tube 410. Under the action of the electric field, the charged molten salt droplets are adsorbed and collected on the surface of the anode tube 410, and finally flow into the bottom end of the heat exchanger section II 4 along the anode tube 410.

[0039] In order to balance heat exchange efficiency and desalination efficiency, under preferred conditions, the radius ratio of the second heat exchange outer tube 42 to the second heat exchange inner tube 41 is 1.1:1 to 2:1.

[0040] In order to improve the collection efficiency of charged molten salt droplets and the molten salt separation efficiency of the electric field, under preferred conditions, the inner diameter of the anode tube 410 is ≥100mm, preferably 100-250mm, and more preferably 150-200mm.

[0041] To improve the salt and corrosion resistance of the anode tube, under preferred conditions, the material of the anode tube 410 is conductive silicon carbide.

[0042] In order to improve the molten salt removal efficiency of the heat exchanger section II 4, under preferred conditions, the heat exchanger section II 4 is further provided with a plurality of second baffles 45 arranged at intervals along its axial direction, one end of the second baffles 45 being welded to the inner wall of the second heat exchange outer tube 42; more preferably, the second baffles 45 are arranged in an alternating pattern in the heat exchanger section II 4.

[0043] According to the application, preferably, the second spoiler 45 is semi-annular, in which case the heat exchange efficiency of the first flue gas can be further improved.

[0044] In some preferred embodiments of the application, in order to discharge the separated molten salt in the heat exchanger I section 3 and the heat exchanger II section 4 from the desalting heat exchanger, at least one of the bottom end of the front smoke box 37, the bottom end of the rear smoke box 413 or the bottom surface of the salt discharge pipe 17 is provided with a discharge hole 310 for discharging the liquid molten salt separated from the desalting heat exchanger; preferably, the discharge hole 310 is arranged at the bottom end of the front smoke box 37.

[0045] According to the application, in order to facilitate the discharge of the liquid molten salt collected at the bottom of the front smoke box 37 and the bottom of the rear smoke box 413 from the desalting heat exchanger, preferably, the bottom surface of the front smoke box 37 has a slope of 1‰-10‰, preferably 2‰-5‰; preferably, the bottom surface of the salt discharge pipe 17 has a slope of 1‰-10‰, preferably 2‰-5‰; preferably, the bottom surface of the rear smoke box 413 has a slope of 1‰-10‰, preferably 2‰-5‰; more preferably, the bottom surface of the front smoke box 37, the bottom surface of the salt discharge pipe 17 and the bottom surface of the rear smoke box 413 are in the same plane, and the lowest point of the bottom surface of the front smoke box 37 is lower than the lowest point of the bottom surface of the rear smoke box 413.

[0046] In some preferred embodiments of the application, an overflow weir 311 is arranged above the discharge hole 310 for uniformly overflowing the liquid molten salt separated from the desalting heat exchanger, and the overflow weir 311 can also prevent the short circuit of flue gas in the heat exchanger I section 3 and the heat exchanger II section 4.

[0047] According to the application, preferably, in order to improve the corrosion resistance of the front smoke box 37 and the rear smoke box 413, preferably, a first corrosion-resistant layer 316 is arranged in the front smoke box 37; preferably, a second corrosion-resistant layer 416 is further arranged on the inner wall of the rear smoke box 413; preferably, a corrosion-resistant layer is arranged on the inner wall of the salt discharge pipe 17; further preferably, the material of the first corrosion-resistant layer 316 and the second corrosion-resistant layer 416 is independently selected from fused alumina or chrome alumina.

[0048] In the application, in order to improve the heat preservation performance and corrosion resistance of the first heat preservation layer 33 and the second heat preservation layer 43, preferably, the material of the first heat preservation layer 33 and the second heat preservation layer 43 is independently selected from at least one of aluminum silicate, magnesium silicate and calcium silicate, preferably magnesium silicate fiber blanket.

[0049] Preferably, the pressure drop of the tube side of the desalting heat exchanger is less than or equal to 1 kPa, which can meet the requirement of the system on the pressure drop of the equipment and will not affect the negative pressure environment of the waste acid cracking system, thereby ensuring the stable operation of the system.

[0050] According to the application, preferably, the material of the first heat exchange outer tube 32 and the second heat exchange outer tube 42 is independently selected from carbon steel and / or stainless steel, for example, Q245R steel or 321 stainless steel; and the material of the first heat exchange inner tube 33 and the second heat exchange inner tube 43 is independently silicon carbide.

[0051] For the convenience of maintenance, preferably, the bottom surface of the front smoke box 37 is provided with a first maintenance hole 320 and / or the bottom surface of the rear smoke box 413 is provided with a second maintenance hole 420.

[0052] In a preferred embodiment of the application, the desalting heat exchanger is a vertical "n" type structure, and the specific structure is as follows: the desalting heat exchanger comprises a heat exchanger I section 3 and a heat exchanger II section 4, the top end of the heat exchanger I section 3 and the top end of the heat exchanger II section 4 are communicated through a connecting section 9; the bottom end of the heat exchanger I section 3 is provided with a front smoke box 37, and the bottom end of the heat exchanger II section 4 is provided with a rear smoke box 413; the front smoke box 37 and the rear smoke box 413 are communicated through a salt discharge pipe 17, the bottom end of the front smoke box 37 is provided with a discharge hole 310, and the front smoke box 37 and the rear smoke box 413 are both provided with a chromium corundum corrosion-resistant layer.

[0053] The heat exchanger I section 3 comprises, from inside to outside, a first heat exchange inner tube 31, a first heat exchange outer tube 32 and a first heat preservation layer 33; the bottom of the first heat exchange inner tube 31 is provided with a first flue gas inlet 36, the top of the first heat exchange outer tube 32 is provided with a first air outlet 39, and the bottom of the first heat exchange outer tube 32 is provided with a first air inlet 38; the first heat exchange inner tube 31 is provided with a plurality of silicon carbide grid plates arranged along the axial direction of the first heat exchange inner tube 31; the heat exchanger I section 3 is further provided with a plurality of semi-annular first spoiler plates 35 arranged along the length direction thereof; one end of each first spoiler plate 35 is arranged on the inner wall of the first heat exchange outer tube 32, and the other end extends into the lumen of the first heat exchange inner tube 31.

[0054] The heat exchanger II section 4 comprises, from inside to outside, a second heat exchange inner tube 41, a second heat exchange outer tube 42 and a second heat preservation layer 43. The bottom of the second heat exchange inner tube 41 is provided with a second flue gas outlet 46. The top of the second heat exchange outer tube 42 is provided with a second air inlet 48. The bottom of the second heat exchange outer tube 42 is provided with a second air outlet 47. A plurality of silicon carbide anode tubes 410 are arranged in the second heat exchange inner tube 41 in a radial direction. A cathode wire 411 is arranged in the anode tube 410. The inner diameter of the anode tube 410 is 150 mm. A plurality of semi-annular second baffles 45 are arranged in the heat exchanger II section 4 in a length direction. One end of the second baffle 45 is arranged on the inner wall of the second heat exchange outer tube 42, and the other end extends into the lumen of the second heat exchange inner tube 41. The pressure drop of the tube side of the desalination heat exchanger is less than or equal to 1 kPa.

[0055] The bottom surfaces of the front flue gas box 37, the salt discharge pipe 17 and the rear flue gas box 413 are on the same plane, and the slope of the plane is 2 ‰.

[0056] In a preferred embodiment of the present application, the heat exchange method of the salt-containing flue gas in the desalination heat exchanger is as follows:

[0057] (1) The salt-containing flue gas enters the first heat exchange inner tube 31 through the flue gas inlet 36. The first air enters the first heat exchange outer tube 32 through the first air inlet 38, flows in the same direction as the first flue gas, and exchanges heat. During the upward flow of the salt-containing flue gas, the flow path is increased by the disturbance of the first baffle 35. Then, the molten salt droplets are intercepted and collected by the molten salt separation module 34, and drop into the front flue gas box 37, obtaining the first flue gas and the second hot air. The second hot air flows out of the desalination heat exchanger through the first air outlet 39.

[0058] (2) The first flue gas enters the second heat exchange inner tube 41 through the connecting section 9 at the top of the first heat exchange inner tube 31. The second air enters the second heat exchange outer tube 42 through the second air inlet 48, exchanges heat with the first flue gas, and obtains the second flue gas and the fourth hot air. The second flue gas flows out of the desalination heat exchanger through the flue gas outlet 46. The fourth hot air flows out of the desalination heat exchanger through the second air outlet 47.

[0059] During the downward flow of the first flue gas, the flow path is increased by the disturbance of the second baffle 45. Then, under the action of the high-voltage electric field, the charged molten salt entrained in the first flue gas is captured and adheres to the anode tube 410. Finally, it falls into the rear flue gas box 413 along the anode tube 410.

[0060] The molten salt in the rear flue gas box 413 flows into the front flue gas box 37 through the salt discharge pipe 17, and then flows out of the desalination heat exchanger through the discharge hole 310.

[0061] In the present application, the salt removal heat exchanger can remove liquid salt droplets with a particle size of ≤50 μm while heat exchanging, wherein the first heat exchanger 3 removes the molten salt in the salt-containing flue gas by 80% (only the first heat exchanger), the second heat exchanger 4 removes the molten salt in the first flue gas by 90% (only the second heat exchanger), and the total salt removal efficiency of the two-stage salt removal heat exchanger is more than 98%. The salt removal heat exchanger can separate the molten salt while heat exchanging, avoid the crystallization of the molten salt, improve the heat exchange efficiency, solve the problem of the blockage of the molten salt in the subsequent heat exchange equipment and pipelines, and realize the separation and recycling of the salts in the waste sulfuric acid.

[0062] The preferred embodiments of the present application are described in detail above with reference to the drawings, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various specific technical features in any suitable manner. In order to avoid unnecessary repetition, the present application does not further describe various possible combination manners. However, these simple modifications and combinations should also be regarded as the disclosed content of the present application and belong to the protection scope of the present application.

Claims

1. A desalination heat exchanger, characterized by, The heat exchanger I section (3) and the heat exchanger II section (4) are communicated through the connecting section (9) at the top end of the heat exchanger I section (3) and the top end of the heat exchanger II section (4), and are communicated through the salt discharge pipe (17) at the bottom end of the heat exchanger I section (3) and the bottom end of the heat exchanger II section (4); The heat exchanger I section (3) comprises, from inside to outside, a first heat exchange inner tube (31) and a first heat exchange outer tube (32), the bottom of the first heat exchange inner tube (31) is provided with a flue gas inlet (36), the top of the first heat exchange outer tube (32) is provided with a first air outlet (39), and the bottom of the first heat exchange outer tube (32) is provided with a first air inlet (38); The heat exchanger II section (4) comprises, from inside to outside, a second heat exchange inner tube (41) and a second heat exchange outer tube (42), the bottom of the second heat exchange inner tube (41) is provided with a flue gas outlet (46), the top of the second heat exchange outer tube (42) is provided with a second air inlet (48), and the bottom of the second heat exchange outer tube (42) is provided with a second air outlet (47); The heat exchanger I section (3) and the heat exchanger II section (4) are each independently provided with a molten salt separation device, and the molten salt separation device is selected from at least one of a grid plate, a honeycomb plate, a corrugated plate and a high-voltage discharge device, wherein the first heat exchange inner tube (31) is provided with a molten salt separation module (34), and the molten salt separation module (34) comprises a plurality of separation plates arranged axially along the first heat exchange inner tube (31), and the second heat exchange inner tube (41) is provided with a plurality of high-voltage discharge devices arranged axially in parallel.

2. The desalination heat exchanger of claim 1, wherein, The separation plate is filled with structured packing or random packing.

3. The desalination heat exchanger of claim 2, wherein, The separation plate is filled with structured packing.

4. The desalination heat exchanger of claim 3, wherein, The structured packing is selected from at least one of a grid plate, a honeycomb plate and a corrugated plate.

5. The desalination heat exchanger of claim 1, wherein, The heat exchanger I section (3) is further provided with a plurality of first turbulence plates (35) arranged axially along the heat exchanger I section (3), and one end of the first turbulence plate (35) is welded to the inner wall of the first heat exchange outer tube (32).

6. The desalination heat exchanger of claim 5, wherein, The first turbulence plate (35) is semi-annular.

7. The desalination heat exchanger of claim 1, wherein, The high-voltage discharge device comprises an anode tube (410) and a cathode wire (411) arranged in the anode tube (410).

8. The desalination heat exchanger of claim 7, wherein, The inner diameter of the anode tube (410) is greater than or equal to 100 mm.

9. The desalination heat exchanger of claim 8, wherein, The inner diameter of the anode tube (410) is 100-250 mm.

10. The desalination heat exchanger of claim 7, wherein, The material of the anode tube (410) is conductive silicon carbide.

11. The desalination heat exchanger of claim 1, wherein, The heat exchanger II section (4) is further provided with a plurality of second turbulence plates (45) arranged axially along the heat exchanger II section (4), and one end of the second turbulence plate (45) is welded to the inner wall of the second heat exchange outer tube (42).

12. The desalination heat exchanger of claim 11, wherein, The second turbulence plate (45) is semi-annular.

13. The desalination heat exchanger of claim 1, wherein, The bottom end of the heat exchanger I section (3) is provided with a front flue gas tank (37) in communication with the heat exchanger I section (3), the bottom end of the heat exchanger II section (4) is provided with a rear flue gas tank (413) in communication with the heat exchanger II section (4), and the front flue gas tank (37) and the rear flue gas tank (413) are communicated through the salt discharge pipe (17).

14. The desalination heat exchanger of claim 13, wherein, At least one of the bottom end of the front smoke box (37), the bottom end of the rear smoke box (413) or the bottom surface of the salt discharge pipe (17) is provided with a discharge hole (310).

15. The desalination heat exchanger of claim 13, wherein, The bottom surface of the front smoke box (37) has a slope of 1‰-10‰.

16. The desalination heat exchanger of claim 13, wherein, The bottom surface of the front smoke box (37) has a slope of 2‰-5‰.

17. The desalination heat exchanger of claim 13, wherein, The bottom surface of the salt discharge pipe (17) has a slope of 1‰-10‰.

18. The desalination heat exchanger of claim 13, wherein, The bottom surface of the salt discharge pipe (17) has a slope of 2‰-5‰.

19. The desalination heat exchanger of claim 13, wherein, The bottom surface of the rear smoke box (413) has a slope of 1‰-10‰.

20. The desalination heat exchanger of claim 13, wherein, The bottom surface of the rear smoke box (413) has a slope of 2‰-5‰.

21. The desalination heat exchanger of claim 13, wherein, The bottom surface of the front smoke box (37), the bottom surface of the salt discharge pipe (17) and the bottom surface of the rear smoke box (413) are on the same plane, and the lowest point of the bottom surface of the front smoke box (37) is lower than the lowest point of the bottom surface of the rear smoke box (413).

22. The desalination heat exchanger of claim 13, wherein, The inner wall of the front smoke box (37) is provided with a first corrosion-resistant layer (316).

23. The desalination heat exchanger of claim 22, wherein, The material of the first corrosion-resistant layer (316) is fused alumina or chrome alumina.

24. The desalination heat exchanger of claim 13, wherein, The inner wall of the rear smoke box (413) is further provided with a second corrosion-resistant layer (416).

25. The desalination heat exchanger of claim 24, wherein, The material of the second corrosion-resistant layer (416) is fused alumina or chrome alumina.

26. The desalination heat exchanger of claim 1, wherein, The heat exchanger I section (3) further comprises a first heat preservation layer (33) arranged outside the first heat exchange outer pipe (32).

27. The desalination heat exchanger of claim 26, wherein, The material of the first heat preservation layer (33) is at least one of aluminum silicate, magnesium silicate and calcium silicate.

28. The desalination heat exchanger of claim 1, wherein, The heat exchanger II section (4) further comprises a second heat preservation layer (43) arranged outside the second heat exchange outer pipe (42).

29. The desalination heat exchanger of claim 28, wherein, The material of the second heat preservation layer (43) is at least one of aluminum silicate, magnesium silicate and calcium silicate.

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