A large specific surface area high-salt wastewater crystallization device and method

Abstract

The application belongs to the technical field of energy utilization, and relates to a large specific surface area high-salt wastewater crystallization device and method. The device comprises a wind distribution chamber, a rapid drying section, a conical transition section and a secondary drying and settling section. The high-salt wastewater to be treated is uniformly sprayed on the surface of the high-temperature filler in the rapid drying section by a water spraying device to form a large specific surface area film. The high-salt wastewater is rapidly evaporated and crystallized through direct contact heat exchange with the high-temperature filler and high-temperature primary air. The salt generated in the evaporation and crystallization process is attached to the surface of the high-temperature filler and is discharged through the solid material outlet and then collected. The gas passes through the conical transition section and the secondary drying and settling section in sequence and is simultaneously introduced into the high-temperature secondary air. On the one hand, the temperature in the crystallization device and the gas residence time can be controlled to evaporate all the liquid water contained in the gas, which is discharged through the gas outlet. On the other hand, most of the salt attached to the inner wall of the crystallization device can be stripped and settled in the rapid drying section.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of energy utilization, and particularly relates to a large specific surface area high-salt wastewater crystallization device and method. BACKGROUND

[0002] Corrosion and abrasion problems, plugging problems, and high chlorine ion concentration in desulfurization wastewater that is difficult to handle seriously restrict the efficient operation of the desulfurization device. When the limestone-gypsum wet flue gas desulfurization device is in operation, chlorides and heavy metals in the flue gas are continuously enriched in the slurry in the absorption tower, which affects the desulfurization efficiency, and thus desulfurization wastewater is generated. The generated desulfurization wastewater has high salt content and is difficult to handle, which is a technical bottleneck that has plagued the environmental protection work of coal-fired power plants.

[0003] The current conventional high-salt wastewater treatment method adopts direct contact heat exchange between high-temperature flue gas / air and atomized high-salt wastewater. This method has the following disadvantages: 1) The flue gas / air used for heat exchange requires a high temperature, usually 280-500 DEG C, which seriously affects the overall thermal efficiency; 2) The atomized high-salt wastewater is easily carried out of the system by the high-temperature gas before complete evaporation, and needs to be treated twice, resulting in a substantial increase in cost; 3) The heat transfer coefficient in the gas-liquid is small, the reactor volume is large for the same treatment capacity, and the investment cost increases. SUMMARY

[0004] In order to overcome the shortcomings of the prior art, the application provides a large specific surface area high-salt wastewater crystallization device and method. The overall structure of the reaction device is adjusted, not only the heat transfer coefficient is greatly improved by using gas-liquid-solid multiphase heat exchange, but also the specific surface area of the high-salt wastewater heat exchange is greatly improved, so that the crystallization evaporation of the high-salt wastewater can be realized at a lower temperature of the heat exchange gas, and the reactor volume is greatly reduced, which is convenient for engineering application.

[0005] The technical scheme of the application is as follows:

[0006] A large specific surface area high-salt wastewater crystallization device, the large specific surface area crystallization device comprises, from bottom to top, a wind distribution chamber 1, a rapid drying section 2, a conical transition section 3, and a secondary drying and settling section 4 which are connected to each other.

[0007] The wind distribution chamber 1 is connected to the outlet of a hot primary air pipe 6, and a wind distribution plate 9 is arranged between the wind distribution chamber 1 and the rapid drying section 2.

[0008] The rapid drying section 2 is filled with fillers 11, and a material outlet 8 is arranged at the bottom, and a valve is arranged at the material outlet 8; according to the different crystallization treatment capacity of the high-salt wastewater, different numbers of water spraying devices 10 are arranged in the rapid drying section 2.

[0009] The conical transition section 3 is a double-layer hollow cavity structure. The outer hollow cavity structure is only connected to the outlet of the hot secondary air duct 7 and the inlet of the hot air outlet pipe 13, and is not connected to other components. The inner hollow cavity structure is connected to the rapid drying section 2 and the secondary drying settling section 4, and is connected to the outlet of the packing hopper 12. The outlet of the hot air outlet pipe 13 is connected to the inlet of the diagonally arranged hot air branch pipes 14 located in the secondary drying settling section 4. The outlet of each hot air branch pipe 14 is connected to the inlet of two tangential air ducts 15 arranged perpendicular to the hot air branch pipe 14. The outlet of the tangential air ducts 15 leads into the secondary drying settling section 4.

[0010] The secondary drying and settling section 4 is equipped with a gas outlet 16;

[0011] The hot air main duct 5 is connected to an external heat source, and the outlet of the hot air main duct 5 is connected to the inlet of the primary hot air duct 6 and the secondary hot air duct 7, respectively.

[0012] Furthermore, when multiple water spray devices 10 are used, the water spray devices 10 are evenly distributed diagonally around the perimeter, and the water outlet of the water spray device 10 is inclined downward to enter the interior of the packing 11.

[0013] Furthermore, the material of the filler 11 can be selected from quartz sand, fly ash, or spherical plastic particles;

[0014] Furthermore, the water spraying device 10 has multiple fan-shaped holes of 0.2 to 2 mm facing the air distribution plate 9, so that the high-salt wastewater is sprayed into the interior of the packing 11 in a jet-like manner.

[0015] Furthermore, the particle size of the filler 11 is 300-1000μm, of which the 300-500μm particle size filler 11 accounts for 20% by mass, the 500-700μm particle size filler 11 accounts for 50% by mass, and the 700-1000μm particle size filler 11 accounts for 30% by mass.

[0016] A method for crystallizing high-salt wastewater with large specific surface area, comprising the following steps:

[0017] Step 1, Primary Drying Stage: Hot primary air is introduced into the rapid drying section 2 through the air distribution chamber 1. The packing 11 is lifted by friction, and the packing 11 is in a bubbling fluidized state and heated. After the temperature is raised to the required temperature, the high-salt wastewater to be treated is evenly sprayed onto the surface of the high-temperature packing 11 in the rapid drying section 2 by the water spraying device 10, forming a film with a large specific surface area. Through direct contact heat exchange with the high-temperature packing 11 and the hot primary air, the high-salt wastewater evaporates and crystallizes rapidly. The crystallized salt generated during the evaporation and crystallization process adheres to the surface of the high-temperature packing 11. The evaporated gas passes through the conical transition section 3 and the secondary drying settling section 4 in sequence.

[0018] Step II, Secondary Drying Stage: Hot secondary air is introduced into the hollow cavity structure of the outer layer of the conical transition section 3 through hot secondary air pipe 7 to maintain a high background temperature for the conical transition section 3. Then, the hot secondary air is introduced into the secondary drying settling section 4 through hot air outlet pipe 13, hot air branch pipe 14 and tangential air pipe 15. The hot secondary air is used to control the temperature and gas residence time in the crystallization device to ensure that all the liquid water contained in the gas is evaporated and discharged from the gas outlet 16. On the other hand, it blows off most of the crystallized salt attached to the inner wall of the crystallization device in the conical transition section 3 and the secondary drying settling section 4 and settles it into the rapid drying section 2.

[0019] Step III, Crystallized Salt Recovery Stage: Open the valve at material outlet 8. After the packing 11 and the crystallized salt generated in Step I and Step II are discharged from material outlet 8, they are collected. The crystallized salt and packing 11 are separated by screening and sent to the subsequent resource recovery and utilization unit.

[0020] Furthermore, the air volume ratio of the primary hot air to the secondary hot air in the crystallization device is 4:1 to 1:1. The adjustment of the air volume ratio of the primary hot air to the secondary hot air depends on the adhesion of the crystallized salt in the inner cavity of the crystallization device.

[0021] Furthermore, the wind speed at the outlet section of the tangential duct 15 is not less than 15 m / s. The outlet direction of the tangential duct 15 is tangential to the inner wall of the secondary drying and settling section 4.

[0022] Furthermore, the hot air medium entering the hot air main duct 5 can be air or flue gas, and the temperature of the hot air medium is controlled between 90 and 280°C.

[0023] Furthermore, the temperature of the rapid drying section 2 and the conical transition section 3 is controlled at 80-200℃, and the temperature of the gas outlet 16 is controlled at 50-80℃.

[0024] Furthermore, after the crystallization salt recovery stage, the packing material 11 in the device needs to be replenished. The amount of packing material 11 added depends on the bed pressure in the rapid drying section 2.

[0025] The beneficial effects of this invention are:

[0026] (1) The heat transfer coefficient is greatly improved by multiphase heat exchange between gas and liquid, gas and solid, and solid and liquid. The heat exchange gas can achieve complete crystallization and evaporation of high-salt wastewater at a lower temperature by using a large surface area thin film.

[0027] (2) Compared with the traditional direct flue gas drying process, this device can treat the same scale of high-salt wastewater in a smaller volume, which greatly reduces investment costs.

[0028] (3) The heat exchange medium has low temperature requirements, and even the flue gas from the outlet of the induced draft fan of a coal-fired power plant can be used directly for the treatment of high-salt wastewater without affecting the overall thermal efficiency of the machine. Attached Figure Description

[0029] Figure 1 This is a front view of the entire device of the present invention. Figure 2 This is a perspective view of the device of the present invention.

[0030] In the diagram: 1. Air distribution chamber; 2. Rapid drying section; 3. Conical transition section; 4. Secondary drying and settling section; 5. Hot air main duct; 6. Hot primary air duct; 7. Hot secondary air duct; 8. Material outlet; 9. Air distribution plate; 10. Water spray device; 11. Packing material; 12. Packing silo; 13. Hot air outlet pipe; 14. Hot air branch pipe; 15. Tangential air duct; 16. Gas outlet. Detailed Implementation

[0031] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0032] Example

[0033] A crystallization device for high-salt wastewater with large specific surface area, wherein the large specific surface area crystallization device comprises, from bottom to top, an interconnected air distribution chamber 1, a rapid drying section 2, a conical transition section 3, and a secondary drying and settling section 4.

[0034] The air distribution chamber 1 is connected to the outlet of the hot primary air duct 6, and an air distribution plate 9 is provided between the air distribution chamber 1 and the rapid drying section 2.

[0035] The rapid drying section 2 is filled with filler 11 and has a material outlet 8 at the bottom, with a valve at the material outlet 8; depending on the amount of high-salt wastewater crystallization treated, the rapid drying section 2 is equipped with different numbers of water spray devices 10.

[0036] The conical transition section 3 is a double-layer hollow cavity structure. The outer hollow cavity structure is only connected to the outlet of the hot secondary air duct 7 and the inlet of the hot air outlet pipe 13, and is not connected to other components. The inner hollow cavity structure is connected to the outlet of the packing hopper 12. The outlet of the hot air outlet pipe 13 is connected to the inlet of the diagonally arranged hot air branch pipes 14 located in the secondary drying and settling section 4. The outlet of each hot air branch pipe 14 is connected to the inlet of two tangential air ducts 15 arranged perpendicular to the hot air branch pipe 14. The outlet of the tangential air ducts 15 leads into the secondary drying and settling section 4.

[0037] The secondary drying and settling section 4 is equipped with a gas outlet 16;

[0038] The hot air main duct 5 is connected to an external heat source, and the outlet of the hot air main duct 5 is connected to the inlet of the primary hot air duct 6 and the secondary hot air duct 7, respectively.

[0039] Six water spray devices 10 are provided, and they are evenly distributed around the four corners. The water outlet of the water spray device 10 is inclined downwards and flows into the inside of the packing 11.

[0040] The material of the filler 11 can be selected as quartz sand;

[0041] The water spraying device 10 has multiple 1mm fan-shaped holes facing the air distribution plate 9, and the high-salt wastewater is sprayed into the interior of the packing 11 in a jet-like manner.

[0042] The filler material 11 has a particle size of 300-1000μm, of which 300-500μm particle size filler 11 accounts for 20% by mass, 500-700μm particle size filler 11 accounts for 50% by mass, and 700-1000μm particle size filler 11 accounts for 30% by mass.

[0043] The primary hot air, at a temperature of 160℃ and a pressure of 4500Pa, enters the rapid drying section 2 through the air distribution chamber 1 and the air hood on the air distribution plate 9. The air outlet direction of the air hood is inclined downwards. Through friction, the packing material 11 is lifted, and the packing material 11 is in a bubbling fluidized state and heated to 140℃. Then, the high-salt wastewater to be treated is evenly sprayed onto the surface of the high-temperature packing material 11 in the rapid drying section 2 by the water spraying device 10, forming a large specific surface area film. Through direct contact heat exchange with the high-temperature packing material 11 and the primary hot air, the volume ratio of the primary hot air to the high-salt wastewater is 16000 Nm3 / m3. The high-salt wastewater evaporates and crystallizes rapidly. The crystallized salt generated during the evaporation and crystallization process adheres to the surface of the high-temperature packing material 11. The evaporated gas passes sequentially through the conical transition section 3 and the secondary drying settling section 4. The secondary hot air enters the conical drying section 4 through the secondary hot air duct 7. Inside the hollow cavity structure of the outer layer of transition section 3, the conical transition section 3 maintains a high background temperature. Then, hot secondary air is introduced into the secondary drying and settling section 4 through hot air outlet pipe 13, hot air branch pipe 14, and tangential air pipe 15. The volume ratio of hot secondary air to high-salt wastewater is 4000 Nm3 / m3. The hot secondary air controls the temperature and gas residence time in the crystallization device to ensure that all liquid water contained in the gas is evaporated and discharged from gas outlet 16. On the other hand, it can blow off most of the crystallized salt attached to the inner wall of the crystallization device in the conical transition section 3 and the secondary drying and settling section 4 and settle it into the rapid drying section 2. After opening the valve at the material outlet 8, the packing 11 and the crystallized salt generated in steps I and II are discharged from the solid material outlet 8 and collected. The crystallized salt and packing 11 are separated by screening and sent to the subsequent resource recovery and utilization unit.

[0044] The ratio of primary hot air to secondary hot air volume is adjusted based on the adhesion of crystalline salt within the crystallization device. The air velocity at the outlet section of tangential duct 15 is not less than 15 m / s. The outlet direction of tangential duct 15 is tangential to the inner wall of the secondary drying settling section 4. The hot air medium entering the main hot air duct 5 can be air or flue gas. The temperature of the rapid drying section 2 and the conical transition section 3 is controlled between 80 and 200℃, and the temperature of the gas outlet 16 is controlled between 50 and 80℃. After the crystalline salt recovery stage, the packing material 11 in the device needs to be replenished. The amount of packing material 11 added depends on the bed pressure in the rapid drying section 2. The salt removal rate in high-salt wastewater reaches over 95%.

[0045] This invention includes, but is not limited to, the present embodiment. It should be noted that, for those skilled in the art, other methods can be used to make substitutions without departing from the technical principles of this invention, and these substitutions should also be considered within the scope of protection of this invention.

Claims

1. A method for crystallizing high-salt wastewater with large specific surface area, characterized in that, A crystallization device for high-salt wastewater with large specific surface area is adopted, which includes, from bottom to top, interconnected air distribution chamber (1), rapid drying section (2), conical transition section (3), and secondary drying and settling section (4). The air distribution chamber (1) is connected to the outlet of the hot primary air duct (6), and an air distribution plate (9) is provided between the air distribution chamber (1) and the rapid drying section (2). The rapid drying section (2) is filled with filler (11) and has a material outlet (8) at the bottom. A valve is installed at the material outlet (8). Depending on the amount of high-salt wastewater crystallization treated, the rapid drying section (2) is equipped with different numbers of water spray devices (10). The conical transition section (3) is a double-layer hollow cavity structure. The outer hollow cavity structure is only connected to the outlet of the hot secondary air pipe (7) and the inlet of the hot air outlet pipe (13), and is not connected to other components. The inner hollow cavity structure is connected to the rapid drying section (2) and the secondary drying settling section (4), and is connected to the outlet of the packing hopper (12). The outlet of the hot air outlet pipe (13) is connected to the inlet of the hot air branch pipe (14) arranged diagonally in the secondary drying settling section (4). The outlet of each hot air branch pipe (14) is connected to the inlet of two tangential air pipes (15) arranged perpendicular to the hot air branch pipe (14). The outlet of the tangential air pipe (15) leads into the secondary drying settling section (4). The secondary drying and settling section (4) is equipped with a gas outlet (16). The hot air main pipe (5) is connected to an external heat source, and the outlet of the hot air main pipe (5) is connected to the inlet of the primary hot air pipe (6) and the secondary hot air pipe (7); The method includes the following steps: Step I, Primary Drying Stage: Hot primary air is introduced into the rapid drying section (2) through the air distribution chamber (1). The packing (11) is lifted by friction. The packing (11) is in a bubbling fluidized state and is heated. After the temperature is raised to the required temperature, the high-salt wastewater to be treated is evenly sprayed onto the surface of the high-temperature packing (11) in the rapid drying section (2) by the water spraying device (10). A film with a large specific surface area is formed. Through direct contact heat exchange with the high-temperature packing (11) and hot primary air, the high-salt wastewater evaporates and crystallizes rapidly. The crystallized salt generated during the evaporation and crystallization process adheres to the surface of the high-temperature packing (11). The evaporated gas passes through the conical transition section (3) and the secondary drying sedimentation section (4) in sequence. Step II, Secondary Drying Stage: Hot secondary air is introduced into the hollow cavity structure of the outer layer of the conical transition section (3) through the hot secondary air pipe (7) to maintain the high temperature background temperature of the conical transition section (3). Then, the hot secondary air is introduced into the secondary drying settling section (4) through the hot air outlet pipe (13), the hot air branch pipe (14) and the tangential air pipe (15). The hot secondary air is used to control the temperature and gas residence time in the crystallization device to ensure that all the liquid water contained in the gas is evaporated and discharged from the gas outlet (16). On the other hand, it blows off most of the crystallized salts attached to the inner wall of the crystallization device in the conical transition section (3) and the secondary drying settling section (4) and settles them into the rapid drying section (2). Step III, Crystallized Salt Recovery Stage: Open the valve at the material outlet (8), and the packing (11) and the crystallized salt generated in Step I and Step II are discharged from the material outlet (8) and collected. The crystallized salt and packing (11) are separated by screening and sent to the subsequent resource recovery and utilization unit. The temperature of the rapid drying section (2) and the conical transition section (3) is controlled at 80~200 ℃, and the temperature of the gas outlet (16) is controlled at 50~80 ℃.

2. The crystallization method for high-salinity wastewater with large specific surface area according to claim 1, characterized in that, When multiple water spray devices (10) are used, the water spray devices (10) are evenly distributed diagonally around the perimeter, and the water outlet of the water spray device (10) is tilted downwards to enter the interior of the packing (11).

3. The crystallization method for high-salinity wastewater with large specific surface area according to claim 1, characterized in that, The filler (11) is made of quartz sand, fly ash or spherical plastic particles.

4. The crystallization method for high-salinity wastewater with large specific surface area according to claim 1, characterized in that, The water spray device (10) has multiple fan-shaped holes of 0.2~2mm facing the air distribution plate (9), and the high-salt wastewater is sprayed into the interior of the packing material (11) in a spraying manner.

5. The crystallization method for high-salinity wastewater with large specific surface area according to claim 1, characterized in that, The air volume ratio of primary hot air to secondary hot air in the crystallization device is 4:1 to 1:

1. The adjustment of the air volume ratio of primary hot air to secondary hot air depends on the adhesion of crystallized salt in the inner cavity of the crystallization device.

6. The crystallization method for high-salinity wastewater with large specific surface area according to claim 1, characterized in that, The wind speed at the outlet section of the tangential duct (15) is not less than 15 m / s; the outlet direction of the wind in the tangential duct (15) is tangential to the inner wall of the secondary drying and settling section (4).

7. The crystallization method for high-salinity wastewater with large specific surface area according to claim 1, characterized in that, The hot air medium in the hot air inlet main pipe (5) is selected as air or flue gas, and the temperature of the hot air medium is controlled at 90~280 ℃.

8. The crystallization method for high-salinity wastewater with large specific surface area according to claim 1, characterized in that, After the crystallization salt recovery stage, the packing (11) in the device needs to be replenished. The amount of packing (11) added depends on the bed pressure in the rapid drying section (2).

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