A high-salt wastewater evaporation and crystallization method

Abstract

The invention relates to the technical field of wastewater evaporation, and discloses a high-salt wastewater evaporation and crystallization method, comprising: S1: wastewater is injected into a horizontal stirring evaporator, an outer scraper rotates at a low speed, and the wastewater is stirred so that the wastewater is heated evenly; S2: a steel ball is put into an evaporation tank, and the outer scraper rotates forward and reversely at a set angle in a cycle, and the set angle decreases by an equal amount as the cycle time increases; S3: in S2, the outer scraper rotates forward at a low speed, and the extrusion blades in the outer scraper are coaxially reversed with the outer scraper, and the steel ball is staggered and extruded between the extrusion blades and the outer scraper and moves downward, and impurity particles inside fall off to the bottom during the extrusion process; the steel ball is easy to absorb crystals, has elastic deformation ability and scale cleaning characteristics, and the high-speed and low-speed inner and outer scrapers rotate oppositely to form an extrusion surface to squeeze the steel ball, so that broken crystals continue to be generated in the steel ball and enter the waste liquid, and the dispersed crystals can be used as the starting point of crystal growth to accelerate crystal generation, thereby improving the crystal generation speed.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater evaporation, in particular to a high-salt wastewater evaporation and crystallization method. Background Art

[0002] High-salinity wastewater can be separated from impurities and liquid by evaporation and crystallization. The most commonly used one is the negative pressure horizontal evaporation crystallizer. The negative pressure in the horizontal tank reduces the evaporation temperature of the liquid in the tank to achieve low-temperature evaporation. A large amount of liquid is injected into the horizontal tank. The scraper in the horizontal tank continuously disperses the internal liquid evenly to facilitate heating, and disperses the crystal particles remaining on the wall of the cylinder. However, the disadvantage of the horizontal tank is that after the liquid is injected, the liquid level is high and the crystallization is slow.

[0003] A Chinese patent discloses a method for treating industrial high-salt wastewater (CN115818904B). The patent adds a stainless steel wire mesh. The stainless steel wire mesh can absorb crystals on its inner and outer surfaces and in its meshes, increasing the amount of crystals adsorbed per unit area and achieving better adsorption effects. However, the patent requires that the stainless steel wire mesh be separated from the crystallization equipment after the crystals are adsorbed, and the stainless steel wire mesh that adsorbs the crystals be beaten to separate the crystals from the stainless steel wire mesh, thereby recovering the crystals. However, the negative pressure evaporator cannot maintain the internal negative pressure environment if the steel wire mesh is continuously discharged, thereby increasing the temperature required for evaporation and increasing the amount of heat source used. Summary of the invention

[0004] The object of the present invention is to provide a method for evaporating and crystallizing high-salt wastewater to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A high-salt wastewater evaporation and crystallization method, comprising:

[0007] S1: Wastewater is injected into the horizontal stirring evaporator. The wastewater is at room temperature, which is far below the evaporation temperature. Crystallization is impossible or difficult to occur at this stage. At this stage, the outer scraper rotates at a low speed to stir the wastewater so that the wastewater is heated evenly and quickly reaches the evaporation temperature point. The evaporation temperature point is adjusted and selected according to the negative pressure until the wastewater reaches the evaporation temperature point;

[0008] S2: Put steel wool into the evaporation tank, and the outer scraper rotates forward and reverse at a set angle. The set angle decreases as the cycle time increases, so that the steel wool moves inside the waste liquid. In the initial stage, since there are few crystals in the liquid, the steel wool mainly moves inside the waste liquid, which accelerates the formation of crystals inside the steel wool. The steel wool will accumulate at the bottom of the tank due to gravity. At this time, the outer scraper rotates forward and reverse to make the steel wool sway left and right in the waste liquid. At the same time, the contact between the steel wool and the tank body can prevent crystallization on the inner wall of the tank, and also cleans the tank body. As the evaporation liquid level decreases, the set angle of the outer scraper gradually decreases, thereby ensuring that the steel wool is inside the waste liquid;

[0009] S3 is interspersed in S2 and executed multiple times: in S2, the outer scraper rotates forward at a low speed, and the extrusion blades inside the outer scraper rotate coaxially with the outer scraper. The steel wool is lifted by the low-speed outer scraper until it tilts and slides downward toward the extrusion blades, and is affected by the interlacing of the extrusion blades and the outer scraper. The steel wool is interlaced and squeezed between the extrusion blades and the outer scraper and moves downward. During the extrusion process, the impurity particles inside fall off to the bottom, and then the S2 step is repeated. After the steel wool has settled in the wastewater for a period of time, crystals will be generated. Therefore, the outer scraper and the extrusion blades rotate synchronously and oppositely. The low-speed outer scraper can slowly lift the steel wool to a high point and then pass through the extrusion blades when it descends. The extrusion blades move in the opposite direction at a high speed. Therefore, the steel wool is easily squeezed and beaten by the extrusion blades, causing the crystals in the steel wool to break and separate into small particles that fall into the waste liquid. The dispersed crystals can serve as the starting point of crystal growth to accelerate crystal formation and increase the crystallization rate. The gap between the extrusion blade and the outer scraper will squeeze the steel wool. The steel wool has a good recovery ability. After the steel wool is squeezed and pulled flat, the crystals begin to crush. At this time, after the steel wool passes through the gap, it will still recover to a nearly original shape. If you want to increase the life of the steel wool, you can set an elastic edge on the edge of the extrusion blade, and use the elastic deformation combined with the gap to squeeze the steel wool, thereby crushing the crystals;

[0010] S4: The liquid inside the evaporation tank gradually evaporates to form crystal residues until the water evaporates completely, the discharge end of the evaporation tank is opened, and the steel wool is filtered to discharge the crystal particles through the evaporation tank, and the S3 operation is repeated to generate more crystal particles for further discharge;

[0011] S5: when the crystal particles discharged in step S4 are few or cannot be discharged, the filter screen is removed, the crystal particles in the steel wool are cleaned and shaken off, and the steel wool is collected;

[0012] S6: The evaporated gas enters the condensation end for condensation and the generated condensate is collected to obtain purified water.

[0013] As a further solution of the present invention: S11: the liquid level height of the wastewater injected into the evaporation tank is consistent with the radius of the evaporation tank, and the starting angle of the positive and reverse rotation of the outer scraper is 180 degrees. When the liquid surface cannot be observed in the evaporation tank, repeat the S3 operation or lock the outer scraper and the extrusion fan blade to rotate synchronously. At this time, the area of ​​the liquid surface is the largest, thereby increasing the evaporation rate.

[0014] As a further solution of the present invention: S21: The steel wool is evenly placed at multiple points along the axial direction of the evaporator. After the placement is completed, the extrusion fan blade rotates one circle at a low speed. Since the horizontal evaporator has a long axial length, single-point placement can easily cause the steel wool to accumulate in the same position. Therefore, multi-point placement can ensure the uniformity of the distribution of the steel wool.

[0015] As a further solution of the present invention: S22: the sewage injection end and the steel wool injection end are located at the same end of the top surface of the evaporation tank and are released synchronously and evenly. The steel wool is injected in advance, but the sewage injection end and the steel wool are released synchronously. The steel wool will enter the tank body with the water flow at the sewage injection end and flow to one end under the influence of the water flow. During the water flow process, the steel wool can be continuously put in and then dispersed under the influence of the water flow.

[0016] As a further solution of the present invention: S41: a filter is added at the extrusion blade, the extrusion blade stops rotating, and the angle between any two extrusion blades is adjusted vertically upward, the outer scraper rotates at a low speed, and the steel wool is put into the extrusion blade angle. The particles are removed by the extrusion blade filter to take out the crystal particles.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] Steel wool is added to the closed wastewater treatment device to promote crystal formation, taking advantage of its easy adsorption of crystals, elastic deformation ability and descaling characteristics. The low-speed forward and reverse reciprocating of the outer scraper promotes the steel wool to adsorb crystals in the waste liquid, and the opposite rotation of the high-speed and low-speed inner and outer scrapers forms an extrusion surface to squeeze the steel wool, so that the steel wool continues to produce broken crystals that enter the waste liquid, and the dispersed crystals can serve as the starting point of crystal growth to accelerate crystal formation and increase the speed of crystal generation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0020] Figure 1 A schematic diagram of a method for evaporation and crystallization of high-salinity wastewater;

[0021] Figure 2 It is a schematic diagram of steps S2 and S3 in a method for evaporation and crystallization of high-salt wastewater;

[0022] Figure 3 The present invention is a schematic diagram of an implementation method of external scrapers and extrusion fan blades in a high-salt wastewater evaporation and crystallization method. DETAILED DESCRIPTION

[0023] See also Figure 1 - Figure 3 : In this embodiment: it includes S1: wastewater is injected into the horizontal stirring evaporator, and the outer scraper rotates at a low speed to heat the wastewater evenly until the wastewater reaches the evaporation temperature point.

[0024] In this embodiment: first, the wastewater is at room temperature, which is far below the evaporation temperature. Even in a negative pressure environment, it is still difficult to meet the evaporation temperature, and crystallization cannot occur at this stage. Therefore, at this stage, the outer scraper is rotated at a low speed to stir the wastewater so that the wastewater is heated evenly and reaches the evaporation temperature point quickly. The evaporation temperature point is adjusted and selected according to the size of the negative pressure.

[0025] In this embodiment: S2: a steel wool is put into the evaporation tank, and the outer scraper rotates forward and reverse at a set angle in a cycle, and the set angle decreases by an equal amount as the cycle time increases, so that the steel wool moves inside the waste liquid.

[0026] In this embodiment: the steel wool is put into the evaporation tank to fully contact the liquid. After the wastewater reaches the evaporation temperature, it begins to evaporate, and the liquid is gradually converted into gas and discharged. At this time, crystals begin to form inside, and the crystals are attached to the steel wool. The steel wool is easy to absorb crystals, so that crystals are quickly generated at the steel wool. After the crystals are separated, the dispersed crystals can be used as the starting point of crystal growth to accelerate the formation of crystals. In the initial stage, since there are few crystals in the liquid, the steel wool is mainly located inside the waste liquid to move, which accelerates the formation of crystals in the steel wool. The steel wool is affected by gravity and will accumulate at the bottom of the tank body. At this time, the outer scraper can rotate forward and reverse to make the steel wool shake left and right in the waste liquid. At the same time, the contact between the steel wool and the tank body can avoid the formation of crystals on the inner wall of the tank body, and also play a cleaning role on the tank body. As the evaporation liquid level decreases, the setting angle of the outer scraper gradually decreases, so that the steel wool can be ensured to be located inside the waste liquid.

[0027] In this embodiment: S21: The steel wool is evenly placed at multiple points along the axis of the evaporator, and after the placement is completed, the extrusion fan blade rotates one circle at a low speed. Since the horizontal evaporator has a long axial length, single-point placement can easily cause the steel wool to accumulate at the same position, so multi-point placement can ensure the uniform distribution of the steel wool.

[0028] In this embodiment: S22: The sewage injection end and the steel wool injection end are located at the same end of the top surface of the evaporation tank and are released synchronously and evenly. In this method, the steel wool is injected in advance, but the sewage injection end and the steel wool are released synchronously. The steel wool will enter the tank body with the water flow at the sewage injection end and flow to one end under the influence of the water flow. During the water flow, the steel wool can be continuously put in and then dispersed under the influence of the water flow.

[0029] In this embodiment: S3 is interspersed in S2 and executed multiple times: in S2, the outer scraper rotates forward at a low speed, and the extrusion blades inside the outer scraper rotate coaxially with the outer scraper. The steel wool is lifted by the low-speed outer scraper until it tilts and slides downward toward the extrusion blades, and is affected by the interlacing of the extrusion blades and the outer scraper. The steel wool is interlaced and squeezed between the extrusion blades and the outer scraper and moves downward. During the extrusion process, the impurity particles inside fall off to the bottom, and then the S2 step is repeated.

[0030] In this embodiment: The above describes the crystallization step of the steel wool in step S2. When the steel wool is precipitated in the wastewater for a period of time, crystals will be generated. Therefore, the outer scraper and the extrusion blade rotate synchronously and oppositely. The low-speed outer scraper can slowly lift the steel wool to the high point and then pass through the extrusion blade. The extrusion blade moves in the opposite direction at high speed. Therefore, the steel wool is easily squeezed and beaten by the extrusion blade, so that the crystals in the steel wool are broken and separated into small particles and fall into the waste liquid. The dispersed crystals can be used as the starting point of crystal growth to accelerate the formation of crystals and increase the speed of crystallization. The gap between the extrusion blade and the outer scraper will squeeze the steel wool. The steel wool has a good recovery ability. After the steel wool is squeezed and pulled flat, the crystals begin to crush. At this time, after the steel wool passes through the gap, it will still recover to a shape close to its original shape. If in order to increase the life of the steel wool, an elastic edge can be set at the edge of the extrusion blade, and the steel wool can be squeezed by combining elastic deformation with the gap to crush the crystals.

[0031] In this embodiment, the advantage of inserting S3 in S2 is that after a small amount of crystals are produced, they are separated and crushed to produce new crystals that fall into the waste liquid to accelerate the crystallization, thereby gradually increasing the crystallization rate.

[0032] The above embodiment describes the outer scraper and the extrusion fan blade. For ease of understanding, please refer to Figure 3 The outer scraper and the extrusion blade are coaxially arranged and driven by two motors. The middle of the outer scraper is a sleeve structure, and the middle of the extrusion blade is the central axis. First, insert the central axis into the outer scraper sleeve, and place the fixing screw hole of the central axis in the rectangular space inside the outer scraper. At this time, the extrusion blade is screwed to the central axis. The outer scraper always rotates at a low speed, so this structure can still meet the requirements of use.

[0033] In this embodiment: S4: the liquid inside the evaporation tank gradually evaporates to form crystalline residues until the water is completely evaporated, the discharge end of the evaporation tank is opened, and the steel wool is filtered to discharge the crystal particles through the evaporation tank, and the S3 operation is repeated to generate more crystal particles for further discharge.

[0034] In this embodiment: when discharging, the crystals and steel wool are both at the bottom, so the steel wool needs to be filtered and discharged at the discharge port so that the steel wool is still inside the tank body, and can also be taken out and put in, or the tank body can be tilted. The specific implementation method is adjusted according to demand. After the crystals are filtered, S3 operation can be repeated to continue to separate the crystals in the steel wool, and then S4 can be repeated.

[0035] In this embodiment: S5: When the crystal particles discharged in step S4 are few or cannot be discharged, remove the filter, clean and shake off the steel wool, and then collect the steel wool.

[0036] In this embodiment: S6: the evaporated gas enters the condensation end and condenses to generate condensate, whereupon the condensate is collected to obtain purified water.

[0037] In this embodiment: S11: the liquid level height of the wastewater injected into the evaporation tank is consistent with the radius of the evaporation tank, and the starting angle of the outer scraper for forward and reverse rotation is 180 degrees. When the liquid surface cannot be observed in the evaporation tank, repeat S3 operation or lock the outer scraper and the extrusion fan blade to rotate synchronously.

[0038] In this embodiment: the liquid level height of the wastewater injected into the evaporation tank is consistent with the radius of the evaporation tank. At this time, the surface area of ​​the liquid is the largest, thereby increasing the evaporation rate. Therefore, the starting angle of the outer scraper is 180 degrees to avoid lifting the steel wool out of the liquid. When the liquid surface cannot be observed intuitively, the function of step S2 will lose its effect. At this time, repeat the S3 operation, or select the outer scraper and the extrusion fan blade to run synchronously. The purpose at this time is to continuously disperse or crush the particles, thereby increasing the contact area with the air and accelerating the evaporation of water.

[0039] In this embodiment: S41: a filter is added to the extrusion fan blade, the extrusion fan blade stops rotating, and the angle between any two extrusion fan blades is adjusted vertically upwards, the outer scraper rotates at a low speed, and the steel wool is placed into the angle of the extrusion fan blade. The particles are removed through the extrusion fan blade filter to take out the crystal particles.

[0040] In this embodiment: This method can be used to modify the extrusion blades. Since the extrusion blades mainly use the staggered gaps between the edge and the outer scraper to extrude large particles or steel balls, a filter screen is set in the middle of the extrusion blade or near the central axis to collect the steel balls and filter the crystals at the same time. Figure 2When the extrusion fan blade fixed angle is directly above, the outer scraper rotates and the steel wool will fall into the angle of the extrusion fan blade. If a filter is added, the steel wool can be gradually separated from the crystals.

[0041] What is described above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A high-salt wastewater evaporation and crystallization method, characterized in that: include: S1: Wastewater is injected into the horizontal stirring evaporator, and the outer scraper rotates at a low speed to heat the wastewater evenly until the wastewater reaches the evaporation temperature point; S2: Put a steel wool ball into the evaporation tank, and the outer scraper rotates forward and reverse at a set angle. The set angle decreases as the cycle time increases, so that the steel wool ball moves inside the waste liquid; S3 is interspersed with S2 and executed multiple times: in S2, the outer scraper rotates forward at a low speed, and the extrusion blades in the outer scraper rotate coaxially with the outer scraper, and the steel wool is lifted by the low-speed outer scraper until it slides downward toward the extrusion blades, and is affected by the interlacing of the extrusion blades and the outer scraper. The steel wool is interlaced and squeezed between the extrusion blades and the outer scraper and moves downward. During the extrusion process, the impurity particles inside fall off to the bottom, and then the S2 step is repeated; S4: The liquid inside the evaporation tank gradually evaporates to form crystal residues until the water evaporates completely, the discharge end of the evaporation tank is opened, and the steel wool is filtered to discharge the crystal particles through the evaporation tank, and the S3 operation is repeated to generate more crystal particles for further discharge; S5: when the crystal particles discharged in step S4 are few or cannot be discharged, the filter screen is removed, the steel wool is cleaned and shaken off, and then the steel wool is collected; S6: The evaporated gas enters the condensation end for condensation and the generated condensate is collected to obtain purified water.

2. A high-salt wastewater evaporation and crystallization method according to claim 1, characterized in that: S11: The liquid level height of the wastewater injected into the evaporation tank is consistent with the radius of the evaporation tank. The starting angle of the outer scraper for forward and reverse rotation is 180 degrees. When the liquid surface cannot be observed in the evaporation tank, repeat the S3 operation or lock the outer scraper and the extrusion fan blade to rotate synchronously.

3. A high-salt wastewater evaporation and crystallization method according to claim 1, characterized in that: S21: Place the steel wool evenly at multiple points along the axis of the evaporator. After placement, squeeze the fan blades to rotate one circle at a low speed.

4. A high-salt wastewater evaporation and crystallization method according to claim 1, characterized in that: S22: The sewage injection end and the steel wool ball injection end are located at the same end of the top surface of the evaporation tank and are released synchronously and evenly.

5. A high-salt wastewater evaporation and crystallization method according to claim 1, characterized in that: S41: A filter is added to the extrusion fan blades, the extrusion fan blades stop rotating, and the angle between any two extrusion fan blades is adjusted vertically upwards. The outer scraper rotates at a low speed, and a steel ball is placed into the angle of the extrusion fan blades. The particles are removed by the extrusion fan blade filter, and the crystal particles are taken out.

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