Evaporation crystallization device and its application in producing ammonium chloride from desulfurization wastewater

Abstract

The present invention discloses an evaporation crystallization device and its application in producing ammonium chloride using desulfurization wastewater. The device comprises a kettle body and a first paddle and a pair of second paddles, both of which are rotatably mounted in the kettle body. The pair of second paddles are symmetrically distributed on both sides of the first paddle, and the second paddles are arranged at an acute angle to the first paddle. The first paddle and the pair of second paddles are driven to rotate by a drive assembly. The second paddle comprises a conveying cylinder fixed in the kettle body, a rotating shaft that rotates through the conveying cylinder, and a spirally upwardly extending conveying blade located in the conveying cylinder and mounted on the rotating shaft. An evaporation tray is provided in the upper portion of the kettle body. The conveying cylinder passes through the evaporation tray and is fixedly connected to the evaporation tray. A through hole with a downward opening is provided on the conveying cylinder. The second paddle stirs and transports the liquid in the kettle body upward and causes the liquid to fall onto the evaporation tray. The evaporation crystallization device of the present invention is applied to the evaporation crystallization of ammonium chloride, improves the evaporation efficiency, promotes the improvement of the crystal particle size and uniformity, and the product yield, and is conducive to improving the desulfurization wastewater treatment efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of desulfurization wastewater treatment and salt production, in particular to an evaporation crystallization device and application thereof in producing ammonium chloride by utilizing desulfurization wastewater. Background Art

[0002] Due to environmental protection and water conservation requirements, advanced treatment and reuse of desulfurization wastewater from power plants has become a trend in desulfurization wastewater management. Desulfurization wastewater contains a high concentration of chloride ions. A common treatment for dechlorination is to convert the chloride ions into an ammonium chloride solution, which is then evaporated and crystallized to produce solid ammonium chloride. However, existing evaporation crystallizers suffer from low evaporation efficiency, small crystal size, and low product yield, which also affects the treatment efficiency of desulfurization wastewater. Summary of the Invention

[0003] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and provide an evaporation crystallization device and its application in producing ammonium chloride using desulfurization wastewater, thereby improving evaporation efficiency, promoting the improvement of crystal particle size and uniformity and product yield, and being conducive to improving the desulfurization wastewater treatment efficiency.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] An evaporation crystallization device includes a kettle body and a first paddle and a pair of second paddles, both of which are rotatably installed in the kettle body. The pair of second paddles are symmetrically distributed on both sides of the first paddle, and the second paddles are set at an acute angle to the first paddle. The first paddle and the pair of second paddles are driven to rotate by a driving assembly. The second paddle includes a conveying cylinder fixed in the kettle body, a rotating shaft rotating through the conveying cylinder, and a spirally upward-extending conveying blade located in the conveying cylinder and installed on the rotating shaft. An evaporation tray is provided in the upper part of the kettle body, the conveying cylinder passes through the evaporation tray and is fixedly connected to the evaporation tray. A through hole with an opening facing downward is opened on the conveying cylinder located above the evaporation tray. The second paddles convey the liquid in the kettle body upward while stirring and make the liquid fall onto the evaporation tray.

[0006] A fan wheel is fixed to the shaft of the first paddle. The fan wheel passes through the center of the evaporation tray and is circumferentially slidably connected to the evaporation tray.

[0007] The evaporation tray includes a first annular evaporation portion that is inclined outward and downward, and a second evaporation portion that is formed by the outer end of the first evaporation portion extending upward and obliquely, wherein the outer end of the second evaporation portion is higher than the first evaporation portion.

[0008] The included angle between the second evaporation portion and the first evaporation portion is 165-175 degrees.

[0009] The drive assembly includes a drive shaft, an A bevel gear and a B bevel gear fixed on the drive shaft, and a pair of rotating shafts are each connected to the A bevel gear through a D bevel gear, and the shaft of the first propeller is located between the two D bevel gears, and the first propeller is connected to the B bevel gear through a C bevel gear.

[0010] The upper portion of the conveying cylinder is fixedly connected to the top of the kettle body, and the lower end of the conveying cylinder is opened; the lower portion of the rotating shaft extends out of the conveying cylinder, and a stirring blade is installed at the lower end of the rotating shaft.

[0011] The evaporation crystallization device is used in the production of ammonium chloride using desulfurization wastewater. The desulfurization wastewater is passed into a boiling water regulating tank to balance the water quality. The wastewater outflow is adjusted by the boiling water regulating tank and then passed into a reaction sedimentation tank for flocculation and precipitation separation. The obtained supernatant is passed into a tubular microfilter for filtration. The filtered water is input into a regulating water tank and the pH is adjusted to 1-3 with sulfuric acid. The water is then extracted by a chloride ion extractor to obtain a chlorine-rich extractant and a sodium sulfate solution. The chlorine-rich extractant is passed through an extractant buffer and a chloride ion stripper in sequence. The chlorine-rich extractant reacts with concentrated ammonia water added to the chloride ion stripper to produce an ammonium chloride solution and a regenerated extractant. The ammonium chloride solution is evaporated and crystallized by the evaporation crystallization device to obtain ammonium chloride crystals.

[0012] The beneficial effects of the present invention are as follows: by arranging the first paddle and the pair of second paddles distributed in different positions and directions, the ammonium chloride solution is heated evenly during evaporation and crystallization; by the structural arrangement of the evaporation plate and the arrangement of the second paddle containing conveying blades, double evaporation of the liquid surface and the liquid on the surface of the evaporation plate is achieved; by the arrangement of the impeller, the flow and discharge of the steam are accelerated, thereby improving the evaporation efficiency, promoting the improvement of the crystal particle size and uniformity and the product yield, and being beneficial to improving the desulfurization wastewater treatment efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural diagram of the present invention;

[0014] Figure 2 for Figure 1 Enlarged view of point A in the middle;

[0015] Figure 3 for Figure 1 Enlarged view of point B in the middle;

[0016] Figure 4 for Figure 1 Partial cross-section along the CC direction;

[0017] Figure 5 This is a top view of the evaporator and impeller.

[0018] In the figure: kettle body 1, mounting box 11, first paddle 2, C bevel gear 21, paddle 22, second paddle 3, conveying cylinder 31, through hole 311, rotating shaft 32, conveying blade 33, stirring blade 34, D bevel gear 35, drive assembly 4, drive shaft 41, A bevel gear 42, B bevel gear 43, evaporation plate 5, first evaporation part 51, second evaporation part 52, slide rail 53, fan wheel 6, outer ring part 61, inner ring part 62, fan blade 63, slide groove 64. DETAILED DESCRIPTION

[0019] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0020] Example 1

[0021] like Figures 1 to 5 As shown, an evaporation crystallization device includes a kettle body 1 and a first paddle 2 and a pair of second paddles 3, which are rotatably installed in the kettle body 1, the lower end of the shaft of the first paddle 2 is fixed with a blade 22, and the pair of second paddles 3 are symmetrically distributed on both sides of the first paddle 2, the second paddle 3 is set at an acute angle to the first paddle 2, and the angle between the second paddle 3 and the first paddle 2 is 25-50 degrees; the first paddle 2 and the pair of second paddles 3 are driven to rotate by a driving component 4; specifically, the driving component 4 includes a driving shaft 41, an A bevel gear 42 and a B bevel gear 43 fixed on the driving shaft 41, the pair of rotating shafts 32 are each meshed and connected to the A bevel gear 42 through a D bevel gear 35, the shaft of the first paddle 2 is between the two D bevel gears 35, and the first paddle 2 is meshed and connected to the B bevel gear 43 through a C bevel gear 21.

[0022] The second paddle 3 includes a conveying cylinder 31 fixed in the kettle body 1, a rotating shaft 32 that rotates through the conveying cylinder 31, and a spirally upward extending conveying blade 33 located in the conveying cylinder 31 and installed on the rotating shaft 32. The upper part of the conveying cylinder 31 is fixedly connected to the top of the kettle body 1, and the lower end of the conveying cylinder 31 is open; the lower part of the rotating shaft 32 extends out of the conveying cylinder 31 and the lower end of the rotating shaft 32 is installed with 34.

[0023] The drive shaft 41 is driven by a motor. This rotation drives the A bevel gear 42 and the B bevel gear 43. The A bevel gear 42 in turn drives the two D bevel gears 35, thereby rotating the rotating shaft 32. This, in turn, stirs the liquid in the kettle 1 while simultaneously transporting it to a higher level. The B bevel gear 43 rotates, driving the C bevel gear 21, which in turn rotates the first paddle 2, thereby stirring the liquid. A mounting housing 11 is fixed to the top of the kettle 1. The drive assembly 4 is mounted within this mounting housing 11. The rotating shaft 32 and the shaft of the first paddle 2 extend into this mounting housing 11.

[0024] An evaporation pan 5 is provided in the upper portion of the kettle body 1 , and the conveying cylinder 31 passes through the evaporation pan 5 and is fixedly connected to the evaporation pan 5 . The conveying cylinder 31 has the function of guiding the fluid on one hand, and has the function of fixing the evaporation pan 5 on the other hand.

[0025] The conveying cylinder 31 located above the evaporation tray 5 is provided with a through hole 311 opening downward, and a plurality of through holes 311 can be provided. The through holes 311 face the evaporation tray 5. The second paddle 3 stirs while conveying the liquid in the kettle body 1 upward and causing the liquid to fall onto the evaporation tray 5. That is, the liquid conveyed upward by the conveying blades 33 flows out through the through hole 311 and then falls onto the evaporation tray 5.

[0026] The evaporation tray 5 includes a first, annular, outward- and downward-sloping evaporation portion 51 and a second, upward-sloping, extending portion 52 from the outer end of the first evaporation portion 51. The outer end of the second evaporation portion 52 is higher than the inner end of the first evaporation portion 51. The angle between the second evaporation portion 52 and the first evaporation portion 51 is 165-175 degrees, and the outer end of the second evaporation portion 52 is 1-3 cm higher than the inner end of the first evaporation portion 51. Furthermore, the longitudinal cross-section of the first evaporation portion 51 is outward- and downward-sloping, while the longitudinal cross-section of the second evaporation portion 52 is outward- and upward-sloping. The second evaporation portion 52 and the first evaporation portion 51 are relatively gently inclined. Due to the structural design of the evaporation tray 5, the liquid being transported upward first falls to the first evaporation portion 51 and flows downward, gradually accumulating at the angle between the second evaporation portion 52 and the first evaporation portion 51. However, the accumulated amount is relatively small, allowing the liquid to evaporate quickly before exiting the evaporation tray 5. Evaporation occurs not only from the liquid surface but also through the evaporation tray 5, increasing the area of evaporation and thereby improving evaporation and crystallization efficiency.

[0027] A fan wheel 6 is fixed to the shaft of the first paddle 2. The fan wheel 6 passes through the center of the evaporator 5 and is circumferentially slidably connected to the evaporator 5. The fan wheel 6 includes a concentrically arranged annular inner ring portion 62 and an annular outer ring portion 61, and circumferentially radiated fan blades 63. The inner ends of the fan blades 63 are fixedly connected to the outer wall of the inner ring portion 62, and the outer ends of the fan blades 63 are fixedly connected to the inner wall of the outer ring portion 61. The annular outer wall of the outer ring portion 61 is recessed to form an annular groove 64. The evaporator 5 includes a through hole located in the center. The annular inner wall of the through hole is raised to form a slide rail 53 that slidably engages with the groove 64.

[0028] The height of the outer ring portion 61 is higher than the inner end of the first evaporation portion 51. When the first paddle 2 rotates, it drives the impeller 6 to rotate. The wind direction of the impeller 6 is upward. The evaporation plate 5 is at a distance of 10-20 cm from the liquid level in the kettle body 1. The rotation of the impeller 6 can promote the upward flow of steam below the evaporation plate 5, and at the same time promote the outflow of steam above the evaporation plate 5, thereby improving the evaporation and crystallization efficiency by improving the steam flow.

[0029] The evaporation crystallization device of the present invention is applied to desulfurization wastewater treatment, and the steps are as follows: the desulfurization wastewater is passed into a boiling water regulating tank to balance the water quality, and the wastewater outflow is adjusted by the boiling water regulating tank, and then the wastewater is passed into a reaction sedimentation tank for flocculation and precipitation separation, the obtained supernatant is passed into a tubular microfilter for filtration, the filtered water is input into a regulating water tank, sulfuric acid is used to adjust the pH value to 1-3, and then the water is extracted by a chloride ion extractor to obtain a chlorine-rich extractant and a sodium sulfate solution; the chlorine-rich extractant is passed through an extractant buffer and a chloride ion stripper in sequence, the chlorine-rich extractant reacts with concentrated ammonia water added to the chloride ion stripper to generate an ammonium chloride solution and a regenerated extractant, and the ammonium chloride solution is evaporated and crystallized by the evaporation crystallization device to obtain ammonium chloride crystals.

[0030] The evaporation crystallization device of the present invention enables the ammonium chloride solution to be heated evenly during evaporation and crystallization by arranging the first paddle 2 and a pair of second paddles 3 distributed in different positions and directions. The structural arrangement of the evaporation plate 5 and the arrangement of the second paddle 3 containing the conveying blades 33 achieve synchronous evaporation of the liquid surface and the liquid on the surface of the evaporation plate 5. The flow and discharge of steam are accelerated by the arrangement of the impeller 6. Combined with the above structural design, the evaporation efficiency is improved, the crystal particle size and product yield are promoted, and it is beneficial to improve the desulfurization wastewater treatment efficiency.

[0031] Comparative Example 1

[0032] The rotating shaft 32 of the evaporation crystallization device is not provided with the conveying blades 33 , and the rest is the same as in the first embodiment.

[0033] Comparative Example 2

[0034] The evaporation crystallization device is not equipped with the evaporation tray 5, and the rest is the same as in Example 1.

[0035] Comparative Example 3

[0036] The evaporation crystallization device is not equipped with a fan wheel 6, and the rest is the same as in Example 1.

[0037] Comparative Example 4

[0038] The evaporation crystallization device is a crystallizer in the prior art.

[0039] Adopt the evaporative crystallization device of comparative example 1-3 and embodiment 1 to carry out the evaporative crystallization of ammonium chloride respectively, find that comparative example 1-3 is compared with embodiment 1, and ammonium chloride crystal yield is respectively low 7.61%, 7.28%, 5.5%; The ammonium chloride crystal particle size that embodiment 1 obtains is uniform and larger (meeting the particle size requirement), 4.63% of the particles are smaller (do not meet the particle size requirement) in the ammonium chloride crystal that comparative example 3 obtains, and 9.1%, 9.22% of the crystals are respectively arranged to not meet the particle size requirement in the ammonium chloride crystals that comparative example 2 and comparative example 1 obtain. Embodiment 1 is compared with comparative example 4, and the ammonium chloride crystal yield of comparative example 4 is low 8.1%, and 9.53% of the obtained ammonium chloride crystals do not meet the required particle size requirement.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An evaporation crystallization device, comprising a kettle (1), a first paddle (2), and a pair of second paddles (3) rotatably mounted in the kettle (1), characterized in that: A pair of second paddles (3) are symmetrically distributed on both sides of the first paddle (2), the second paddles (3) and the first paddle (2) are arranged at an acute angle, the first paddle (2) and the pair of second paddles (3) are driven to rotate by a driving assembly (4), the second paddle (3) comprises a conveying cylinder (31) fixed in the kettle body (1), a rotating shaft (32) rotating through the conveying cylinder (31), and a spirally upwardly extending conveying blade (33) located in the conveying cylinder (31) and mounted on the rotating shaft (32), an evaporation tray (5) is provided in the upper part of the kettle body (1), the conveying cylinder (31) passes through the evaporation tray (5) and is fixedly connected to the evaporation tray (5), a through hole (311) with an opening facing downward is opened on the conveying cylinder (31) located above the evaporation tray (5), and the second paddle (3) conveys the liquid in the kettle body (1) upward while stirring and causes the liquid to fall onto the evaporation tray (5); The difference between the liquid level in the evaporation dish (5) and the kettle body (1) is 10-20 cm; the evaporation dish (5) comprises a first annular evaporation portion (51) tilted outward and downward and a second evaporation portion (52) formed by the outer end of the first evaporation portion (51) extending upward and tilting, and the outer end of the second evaporation portion (52) is higher than the first evaporation portion (51); the angle between the second evaporation portion (52) and the first evaporation portion (51) is 165-175 degrees, and the outer end of the second evaporation portion (52) is 1-3 cm higher than the inner end of the first evaporation portion (51); a fan wheel (6) is fixed to the shaft of the first paddle (2), and the fan wheel (6) passes through the center of the evaporation dish (5) and is circumferentially slidably connected to the evaporation dish (5).

2. An evaporation crystallization device as claimed in claim 1, characterized in that: The driving assembly (4) comprises a driving shaft (41), an A bevel gear (42) and a B bevel gear (43) fixed on the driving shaft (41); a pair of rotating shafts (32) are respectively connected to the A bevel gear (42) by meshing transmission via a D bevel gear (35); the shaft of the first propeller (2) is located between the two D bevel gears (35); and the first propeller (2) is connected to the B bevel gear (43) by meshing transmission via a C bevel gear (21).

3. An evaporation crystallization device as claimed in claim 1, characterized in that: The upper portion of the conveying cylinder (31) is fixedly connected to the top of the kettle body (1), and the lower end of the conveying cylinder (31) is open; the lower portion of the rotating shaft (32) extends out of the conveying cylinder (31), and a stirring blade (34) is installed at the lower end of the rotating shaft (32).

4. An application of the evaporation crystallization device according to any one of claims 1 to 3 in producing ammonium chloride from desulfurization wastewater, characterized in that: The process flow for producing ammonium chloride using desulfurization wastewater is as follows: the desulfurization wastewater is passed into a boiling water regulating tank to balance the water quality, and the wastewater outflow is adjusted by the boiling water regulating tank and then passed into a reaction sedimentation tank for flocculation and precipitation separation. The obtained supernatant is passed into a tubular microfilter for filtration. After filtration, the produced water is input into a regulating water tank and the pH is adjusted to 1-3 with sulfuric acid. The water is then extracted in a chloride ion extractor to obtain a chlorine-rich extractant and a sodium sulfate solution. The chlorine-rich extractant is passed through an extractant buffer and a chloride ion stripper in sequence, and the chlorine-rich extractant reacts with concentrated ammonia water added to the chloride ion stripper to produce an ammonium chloride solution and a regenerated extractant. The ammonium chloride solution is evaporated and crystallized by an evaporation crystallization device to obtain ammonium chloride crystals.

Images