Large-specific-surface-area high-salinity wastewater crystallization device and method

Abstract

The invention belongs to the technical field of energy utilization, and relates to a large-specific-surface-area high-salinity wastewater crystallization device and method.The device comprises an air distribution chamber, a rapid drying section, a conical transition section and a secondary drying and settling section, high-salinity wastewater to be treated is evenly sprayed to the surface of high-temperature filler in the rapid drying section through a water spraying device, and a large-specific-surface-area film is formed; through direct contact type heat exchange with the high-temperature filler and high-temperature primary air, the high-salinity wastewater is rapidly evaporated and crystallized, and salt generated in the evaporation and crystallization process is attached to the surface of the high-temperature filler, discharged from a solid material outlet and collected; gas sequentially passes through the conical transition section and the secondary drying and settling section, and high-temperature secondary air is introduced at the same time, so that on one hand, the temperature in the crystallization device and the gas retention time can be controlled to completely evaporate liquid water contained in the gas, and the gas is discharged from a gas outlet; on the other hand, most salt attached to the inner wall of the crystallization device can be blown off and settled to the rapid drying section.

Description

Technical Field

[0001] The invention belongs to the technical field of energy utilization, and in particular relates to a device and method for crystallizing high-salt wastewater with a large specific surface area. Background Art

[0002] Based on the current reality of raw coal blending in the coal-fired power industry and the increasingly stringent environmental protection requirements for ultra-clean flue gas emissions and wastewater reduction, new challenges have been raised for the efficient and stable operation of desulfurization facilities. Problems such as corrosion and wear, blockage, and excessive chloride ion concentration in desulfurization wastewater that is difficult to handle during the operation of the desulfurization system 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 absorption tower slurry, affecting the desulfurization efficiency, and thus producing desulfurization wastewater. The desulfurization wastewater produced has a high salt content and is difficult to handle, which has been a technical bottleneck that has plagued the environmental protection work of coal-fired power plants.

[0003] At present, conventional high-salt wastewater treatment methods all use direct contact heat exchange between high-temperature flue gas / air and atomized high-salt wastewater. This approach has the following disadvantages: 1) The flue gas / air temperature required for heat exchange is high, usually between 280 and 500°C, which seriously affects the thermal efficiency of the whole machine; 2) The atomized high-salt wastewater is easily carried out of the system by the high-temperature gas before it is completely evaporated, and requires secondary treatment, resulting in a significant increase in costs; 3) The heat transfer coefficient between gas and liquid is small, and the reactor volume is large for the same processing capacity, which increases the investment cost. Summary of the invention

[0004] In order to overcome the shortcomings of the existing production process, the present invention provides a large specific surface area high-salt wastewater crystallization device and method, adjusts the overall structure of the reaction device, not only utilizes gas, liquid, and solid multiphase heat exchange to greatly improve the heat transfer coefficient, but also greatly increases the heat exchange specific surface area of ​​high-salt wastewater, so that the heat exchange gas can achieve crystallization and evaporation of high-salt wastewater at a lower temperature, and also greatly reduces the volume of the reactor, facilitating its application in engineering.

[0005] The technical solution of the present invention:

[0006] A large specific surface area high-salt wastewater crystallization device, the large specific surface area crystallization device comprises, from bottom to top, an air distribution chamber 1, a rapid drying section 2, a conical transition section 3, and a secondary drying sedimentation section 4 which are interconnected;

[0007] 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;

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

[0009] The conical transition section 3 is a double-layer hollow cavity structure, wherein 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 quick drying section 2 and the secondary drying sedimentation section 4, and is connected to the outlet of the filling bin 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 sedimentation section 4, and the outlet of each hot air branch pipe 14 is respectively connected to the inlet of two tangential air ducts 15 arranged perpendicular to the hot air branch pipe 14, and the outlet of the tangential air duct 15 leads to the secondary drying sedimentation section 4;

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

[0011] 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 hot primary air pipe 6 and the hot secondary air pipe 7 respectively.

[0012] Furthermore, when multiple water spray devices 10 are used, the water spray devices 10 are evenly distributed diagonally around the periphery, and the water outlets of the water spray devices 10 are inclined downward to enter the interior of the filler 11;

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

[0014] Furthermore, the water spray device 10 is provided with a plurality of fan-shaped holes of 0.2 to 2 mm in the direction of the air distribution plate 9, and the high-salinity wastewater is injected into the filler 11 in a jet-like manner;

[0015] Further, the particle size of the filler 11 is 300-1000 μm, wherein the filler 11 with a particle size of 300-500 μm accounts for 20% by mass, the filler 11 with a particle size of 500-700 μm accounts for 50% by mass, and the filler 11 with a particle size of 700-1000 μm accounts for 30% by mass;

[0016] A method for crystallizing high-salt wastewater with a large specific surface area, the steps are as follows:

[0017] Step I, primary drying stage: hot primary air is passed through the air distribution chamber 1 into the rapid drying section 2, and the filler 11 is lifted by friction, and the filler 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 on the surface of the high-temperature filler 11 in the rapid drying section 2 by the water spray device 10 to form a large specific surface area film. Through direct contact heat exchange with the high-temperature filler 11 and the hot primary air, the high-salt wastewater evaporates and crystallizes rapidly, and the crystalline salt generated during the evaporation and crystallization process adheres to the surface of the high-temperature filler 11, and the evaporated gas passes through the conical transition section 3 and the secondary drying sedimentation 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 the hot secondary air duct 7 to maintain the high temperature background temperature of the conical transition section 3, and then the hot secondary air is introduced into the secondary drying and settling section 4 through the hot air outlet pipe 13, the hot air branch pipe 14 and the tangential air duct 15. The hot secondary air is used to control the temperature and gas residence time in the crystallization device on the one hand, to ensure that all liquid water contained in the gas is evaporated and discharged from the gas outlet 16; on the other hand, 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 is blown off and settled to the rapid drying section 2;

[0019] Step III, crystallized salt recovery stage: open the valve at the material outlet 8, the filler 11 and the crystallized salt generated in step I and step II are discharged from the material outlet 8 and collected, and the crystallized salt and the filler 11 are separated by screening and sent to the subsequent resource recovery and utilization unit.

[0020] Furthermore, the air volume ratio of hot primary air to hot secondary air in the crystallization device is 4:1 to 1:1, and the air volume ratio of hot primary air to hot secondary air is adjusted according to the adhesion of crystallized salt in the inner cavity of the crystallization device.

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

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

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

[0024] Furthermore, after the crystallized salt recovery stage, the filler 11 in the device needs to be supplemented, and the amount of filler 11 added depends on the bed pressure in the rapid drying section 2.

[0025] Beneficial effects of the present invention:

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

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

[0028] (3) The temperature requirement of the heat exchange medium is low, and even the exhaust gas from the induced draft fan of a coal-fired power plant can be directly used to treat high-salt wastewater without affecting the thermal efficiency of the whole machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a front view of the entire device of the present invention. Figure 2 It is a three-dimensional diagram of the device of the present invention.

[0030] In the figure: 1 air distribution room; 2 rapid drying section; 3 conical transition section; 4 secondary drying and settling section; 5 hot air main pipe; 6 hot primary air duct; 7 hot secondary air duct; 8 material outlet; 9 air distribution plate; 10 water spray device; 11 filler; 12 filler bin; 13 hot air outlet pipe; 14 hot air branch pipe; 15 tangential air duct; 16 gas outlet. DETAILED DESCRIPTION

[0031] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and technical solutions.

[0032] Example

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

[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 quick drying section 2 is filled with fillers 11, and a material outlet 8 is provided at the bottom, and a valve is provided at the material outlet 8; according to the different crystallization treatment amounts of high-salt wastewater, different numbers of water spray devices 10 are provided in the quick drying section 2;

[0036] The conical transition section 3 is a double-layer hollow cavity structure, wherein 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 filling bin 12, and the outlet of the hot air outlet pipe 13 is connected to the inlet of the diagonally arranged hot air branch pipe 14 located in the secondary drying and settling section 4, and each outlet of the hot air branch pipe 14 is respectively connected to the inlet of two tangential air ducts 15 arranged perpendicular to the hot air branch pipe 14, and the outlet of the tangential air duct 15 leads to the secondary drying and settling section 4;

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

[0038] 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 hot primary air pipe 6 and the hot secondary air pipe 7 respectively.

[0039] Six water spray devices 10 are provided, and are evenly distributed diagonally around the periphery, and the water outlets of the water spray devices 10 are inclined downward to pass into the interior of the filler 11;

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

[0041] The water spray device 10 has a plurality of 1 mm fan-shaped holes facing the air distribution plate 9, and the high-salt wastewater is injected into the filler 11 in a jet shape;

[0042] The particle size of the filler 11 is 300-1000 μm, of which the mass of the filler 11 with a particle size of 300-500 μm accounts for 20%, the mass of the filler 11 with a particle size of 500-700 μm accounts for 50%, and the mass of the filler 11 with a particle size of 700-1000 μm accounts for 30%;

[0043] The hot primary air has a temperature of 160°C and a pressure of 4500Pa. It passes through the air distribution chamber 1 and the wind cap on the air distribution plate 9 into the rapid drying section 2. The air outlet direction of the wind cap is inclined downward, and the filler 11 is lifted up by friction. The filler 11 is in a bubbling fluidized state and is heated. After the temperature is raised to 140°C, the high-salt wastewater to be treated is evenly sprayed on the surface of the high-temperature filler 11 in the rapid drying section 2 by the water spray device 10 to form a large specific surface area film. Through direct contact heat exchange with the high-temperature filler 11 and the hot primary air, the volume ratio of the hot primary air to the high-salt wastewater is 16000Nm3 / m3. The high-salt wastewater evaporates and crystallizes rapidly. The crystalline salt generated during the evaporation and crystallization process adheres to the surface of the high-temperature filler 11. The evaporated gas passes through the conical transition section 3 and the secondary drying sedimentation section 4 in turn; the hot secondary air passes through the hot secondary air duct 7 into the conical Inside the hollow cavity structure of the outer layer of the transition section 3, the high temperature background temperature is maintained for the conical transition section 3, and then the hot secondary air is introduced into the secondary drying and settling section 4 through the hot air outlet pipe 13, the hot air branch pipe 14 and the tangential air duct 15. The volume ratio of the hot secondary air to the high-salt wastewater is 4000Nm3 / m3. On the one hand, the hot secondary air controls 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, 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 can be blown off and settled to the rapid drying section 2; the valve at the material outlet 8 is opened, and the filler 11 and the crystallized salt generated in step I and step II are discharged from the solid material outlet 8 and collected, and the crystallized salt and the filler 11 are sent to the subsequent resource recovery and utilization unit after screening and separation.

[0044] The air volume ratio of hot primary air and hot secondary air is adjusted according to the adhesion of crystallized salt in the inner cavity of the crystallization device. The wind speed of the outlet section of the tangential air duct 15 is not less than 15m / s. The outlet direction of the wind of the tangential air duct 15 is tangent to the inner wall of the secondary drying sedimentation section 4. The hot air medium entering the hot air main pipe 5 can be air or flue gas. The temperature of the rapid drying section 2 and the conical transition section 3 is controlled at 80-200°C, and the temperature of the gas outlet 16 is controlled at 50-80°C. After the crystallized salt recovery stage, the filler 11 in the device needs to be supplemented, and the amount of filler 11 added depends on the bed pressure in the rapid drying section 2. The removal rate of salt in high-salt wastewater reaches more than 95%.

[0045] The present invention includes but is not limited to this embodiment. It should be pointed out that for ordinary technicians in this field, other methods can be used to make substitutions without departing from the technical principles of the present invention. These substitutions should also be regarded as the protection scope of the present invention.

Claims

1. A large specific surface area high-salt wastewater crystallization device, characterized in that: The large specific surface area crystallization device comprises, from bottom to top, an air distribution chamber (1), a rapid drying section (2), a conical transition section (3), and a secondary drying sedimentation section (4) which are interconnected; 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 quick drying section (2); The quick drying section (2) is filled with a filler (11) and has a material outlet (8) at the bottom, where a valve is provided. Different numbers of water spray devices (10) are provided in the quick drying section (2) according to the different crystallization treatment amounts of high-salinity wastewater. The conical transition section (3) is a double-layer hollow cavity structure, wherein 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 quick drying section (2) and the secondary drying sedimentation section (4), and is connected to the outlet of the filling bin (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 sedimentation section (4); the outlet of each hot air branch pipe (14) is respectively connected to the inlet of two tangential air ducts (15) arranged perpendicular to the hot air branch pipe (14); and the outlet of the tangential air duct (15) leads to the secondary drying sedimentation section (4); The secondary drying and settling section (4) is provided 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 respectively connected to the inlet of the hot primary air pipe (6) and the hot secondary air pipe (7).

2. A large specific surface area high-salt wastewater crystallization device according to claim 1, characterized in that: When a plurality of water spray devices (10) are used, the water spray devices (10) are evenly distributed diagonally around the periphery, and the water outlets of the water spray devices (10) are inclined downward to pass into the interior of the filler (11).

3. A large specific surface area high-salt wastewater crystallization device according to claim 1, characterized in that: The material of the filler (11) can be selected from quartz sand, fly ash, and spherical plastic particles.

4. A large specific surface area high-salt wastewater crystallization device according to claim 1, characterized in that: The water spray device (10) is provided with a plurality of fan-shaped small holes of 0.2 to 2 mm in the direction of the air distribution plate (9), and the high-salt wastewater is injected into the interior of the filler (11) in a jet-like manner; the particle size of the filler (11) is 300 to 1000 μm, wherein the mass of the filler (11) with a particle size of 300 to 500 μm accounts for 20%, the mass of the filler (11) with a particle size of 500 to 700 μm accounts for 50%, and the mass of the filler (11) with a particle size of 700 to 1000 μm accounts for 30%.

5. A method for crystallizing high-salt wastewater with a large specific surface area, characterized in that: The large specific surface area crystallization method is implemented by using a large specific surface area high-salt wastewater crystallization device as described in any one of claims 1 to 4, and the steps are as follows: Step I, primary drying stage: hot primary air is passed through the air distribution chamber (1) into the rapid drying section (2), and the filler (11) is lifted up by friction. The filler (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 on the surface of the high-temperature filler (11) in the rapid drying section (2) by the water spraying device (10), forming a large specific surface area film. The high-salt wastewater is rapidly evaporated and crystallized by direct contact heat exchange with the high-temperature filler (11) and the hot primary air. The crystalline salt generated during the evaporation and crystallization process adheres to the surface of the high-temperature filler (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 duct (7) to maintain the high temperature background temperature of the conical transition section (3), and then the hot secondary air is introduced into the secondary drying and settling section (4) through the hot air outlet pipe (13), the hot air branch pipe (14) and the tangential air duct (15). The hot secondary air is used to control the temperature and gas residence time in the crystallization device on the one hand, to ensure that all liquid water contained in the gas is evaporated and discharged from the gas outlet (16); on the other hand, 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) is blown off and settled to the rapid drying section (2); Step III, crystallized salt recovery stage: open the valve at the material outlet (8), the filler (11) and the crystallized salt generated in steps I and II are discharged from the material outlet (8) and collected, and the crystallized salt and the filler (11) are separated by screening and sent to the subsequent resource recovery and utilization unit.

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

1. The air volume ratio of hot primary air to hot secondary air is adjusted according to the adhesion of crystallized salt in the inner cavity of the crystallization device.

7. A method for crystallizing high-salt wastewater with a large specific surface area according to claim 5, characterized in that: The wind speed at the outlet section of the tangential air duct (15) is not less than 15 m / s; the outlet direction of the wind from the tangential air duct (15) is tangent to the inner wall surface of the secondary drying and settling section (4).

8. A method for crystallizing high-salt wastewater with a large specific surface area according to claim 5, characterized in that: The hot air medium entering the hot air main pipe (5) can be air or flue gas, and the temperature of the hot air medium is controlled at 90-280°C.

9. A method for crystallizing high-salt wastewater with a large specific surface area according to claim 5, characterized in that: The temperature of the rapid drying section (2) and the tapered transition section (3) is controlled at 80-200°C, and the temperature of the gas outlet (16) is controlled at 50-80°C.

10. A method for crystallizing high-salt wastewater with a large specific surface area according to claim 5, characterized in that: After the crystallized salt recovery stage, the filler (11) in the device needs to be supplemented, and the amount of filler (11) added depends on the bed pressure in the rapid drying section (2).

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