CN108191130B - High-salt high-organic matter wastewater evaporative crystallization anti-scaling treatment device and method - Google Patents
High-salt high-organic matter wastewater evaporative crystallization anti-scaling treatment device and method Download PDFInfo
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- CN108191130B CN108191130B CN201711459330.7A CN201711459330A CN108191130B CN 108191130 B CN108191130 B CN 108191130B CN 201711459330 A CN201711459330 A CN 201711459330A CN 108191130 B CN108191130 B CN 108191130B
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
- C02F5/02—Softening water by precipitation of the hardness
- C02F5/06—Softening water by precipitation of the hardness using calcium compounds
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
- C02F1/042—Prevention of deposits
Abstract
The invention discloses a device and a method for carrying out evaporation crystallization and scale prevention treatment on high-salinity high-organic matter wastewater, and belongs to the technical field of wastewater treatment. Above-mentioned high salt high organic matter waste water evaporation crystallization anti fouling processing apparatus includes: an evaporation chamber; the upper end of the upper circulating pipe is radially connected to the middle part or the middle lower part of the straight section of the evaporation chamber, and the lower end of the upper circulating pipe is connected with the outlet of the heating chamber; the upper part of the central guide cylinder is provided with an oblique cut which is opposite to the direction of the feed inlet of the evaporation chamber and is provided with a plurality of round holes right facing the feed inlet of the evaporation chamber; the outlet of the heating chamber is connected with the lower end of the upper circulating pipe; the upper end of the lower circulating pipe is connected to the lower side of the conical hopper of the evaporation chamber, and the lower end of the lower circulating pipe is connected with an inlet of the first circulating pump; the upper end of the washing leg is connected with the bottom of the conical hopper of the evaporation chamber. The device has simple structure, realizes the uniform distribution of the feed liquid in the evaporation chamber, and effectively prevents the problems of scaling, over-small crystal size, low crystal purity and the like in the evaporation crystallization process.
Description
Technical Field
The invention relates to a wastewater treatment technology and an evaporative crystallization device, in particular to an anti-scaling treatment device and method for evaporative crystallization of high-salinity high-organic wastewater.
Background
High salt waste water refers to the total salt content (Cl) produced in industry-、SO42-、Na+、Ca2+、Mg2+Etc.) higher wastewater. The high-salinity wastewater mainly comes from the industries of chemical industry, petroleum, food processing, printing and dyeing and the like. The waste water discharged from these industries contains a large amount of organic substances in addition to salts. In the prior art, in order to effectively utilize water resources and prevent environmental pollution caused by wastewater discharge, high-salinity wastewater needs to be desalted and subjected to organic matter removal treatment and then recycled.
After advanced treatment and concentration, organic matters in the wastewater are accumulated and contain a large amount of calcium and magnesium ions. For the part of strong brine, the current mainstream treatment process is to recover distilled water by adopting evaporation crystallization and simultaneously produce crystallized salt. However, before the wastewater enters the evaporative crystallization, components such as calcium, magnesium and the like which are easy to cause scaling must be removed through pretreatment, a large amount of medicament needs to be added, and the treatment cost is greatly increased.
In addition, in the evaporative crystallization process, the existing mainstream crystallization device generally has uneven solid-liquid mixing, and particularly, the liquid level position cannot provide uniform solid-liquid distribution, so that the number of seed crystals at the peripheral wall surface or the center is small. As a result, the supersaturation degree of the feed liquid at the liquid level is not sufficiently eliminated, the explosive nucleation occurs, and the crystallized salt is too fine. The fine particle size increases the burden of elutriation purification and centrifugal dewatering. Meanwhile, salt is easily formed on the inner wall of the crystallizer, and the salt falls off to block a bottom pipeline or a salt discharge port.
The structure of the related evaporative crystallization chamber in the prior art is shown in the attached figure 1. The evaporative crystallization chamber has many advantages, because the heated feed liquid enters from the central tube of the evaporation chamber and is conveyed to the position near the liquid level, the evaporation intensity of the liquid level at the central position of the evaporation chamber is high, the evaporation intensity near the cylinder wall is relatively small, and the cylinder wall is relatively difficult to form salt; the feed liquid and the crystals flow axially in the same direction in the evaporation chamber, and the solid and the liquid are uniformly mixed; after the jacket is additionally arranged in the evaporation chamber, solid-liquid separation is convenient, and clear liquid is discharged from the clear liquid transferring port to the next effect, so that the device is more suitable for salt and nitrate co-production. The disadvantages that the heated feed liquid still boils at the uppermost part of the solution in the evaporation chamber, the supersaturation degree of the solution is the largest, the crystal grains are the finest, the supersaturation degree is not favorably and rapidly absorbed by larger crystals, and meanwhile, the retention time of the crystals in the evaporation chamber is difficult to prolong, and the crystals are not favorable for obtaining larger crystals; the large crystals formed are sucked into the lower circulation pipe and crushed after entering the forced circulation pump, and the crushing is more intense particularly when the circulation flow rate is increased for increasing the heat transfer coefficient of the heating chamber, thereby causing excessive crystal nucleus generation.
Patent CN103071310A discloses an evaporative crystallizer comprising: an evaporation chamber; a central drainage tube; an evaporation chamber inner cone; a clear liquid transferring pipe; a crystal growing settling chamber baffling cylinder; an upper circulation pipe; an external circulation feed nozzle; a heating chamber; a lower circulation pipe; a forced circulation pump; salt feet; a secondary steam pipe; a steam exhaust pipe. The evaporative crystallizer has internal and external circulation, and the external circulation consists of an evaporation chamber, an upper circulating pipe, a heating chamber, a forced circulating pump and a lower circulating pipe; the internal circulation of the device consists of a central drainage cylinder, an evaporation chamber inner cone and a crystal growth settling chamber deflection cylinder. The invention can achieve the purposes of further reducing the energy consumption of unit products, prolonging the normal production period and improving the comprehensive economic benefit while producing the salt crystals with large granularity and high purity. However, the technical scheme of the invention is complex, and water resources are wasted in the elutriation process of the prepared salt crystals.
That is, in the conventional center feeding and discharging, or tangential feeding or radial feeding, there is a problem that the feed liquid cannot be completely distributed at various points of the liquid surface, especially at the wall surface, and thus the seed crystals in the feed liquid cannot be distributed therein. This leads to the following problems: after flash evaporation of the feed liquid, no seed crystal provides a condition for crystal growth for the supersaturated feed liquid. In particular, the fine crystals precipitated on the wall surface do not adhere to the seed crystal, and most of the fine crystals adhere to the inner wall to form salt. The salt can fall down at variable time, block the lower part circulation outlet and wash the leg, cause unable operation. Secondly, due to the lack of crystal seed distribution locally, the supersaturated feed liquid after flash evaporation can burst into nucleation to form a large number of fine crystals, and the product granularity requirement of the crystallized salt cannot be met. The granularity of the crystallized salt is too fine, which is not beneficial to subsequent solid-liquid separation, and the smaller the crystal is, the more easily the crystal carries with impurities such as organic matters, and the difficulty is also increased for elutriation.
Disclosure of Invention
The invention provides a device and a method for carrying out evaporative crystallization and scale prevention on high-salinity high-organic wastewater, aiming at solving the problems of scaling, too small crystallization, low crystallization purity, complex structure and the like caused by evaporative crystallization in the wastewater treatment process in the prior art.
In order to solve the technical problems, the invention provides the following technical scheme:
the invention provides a high-salinity high-organic matter wastewater evaporation crystallization anti-scaling treatment device, which comprises: an evaporation chamber;
the upper end of the upper circulating pipe is radially connected to the middle part or the middle-lower part of the straight section of the evaporation chamber, and the lower end of the upper circulating pipe is connected with an outlet of the heating chamber;
the upper part of the central guide cylinder is provided with an oblique cut which is opposite to the direction of the feed inlet of the evaporation chamber and is provided with a plurality of round holes right facing the feed inlet of the evaporation chamber;
the outlet of the heating chamber is connected with the lower end of the upper circulating pipe;
the outlet of the first circulating pump is connected with the inlet of the heating chamber;
the upper end of the lower circulating pipe is connected to the lower side of the conical hopper of the evaporation chamber, and the lower end of the lower circulating pipe is connected with the inlet of the first circulating pump;
the upper end of the washing leg is connected with the bottom of the conical hopper of the evaporation chamber;
the mother liquid standing device is arranged on the lower circulating pipe;
the feed inlet is positioned at the lower part of the mother liquid standing device;
and the secondary steam pipe is arranged at the top of the evaporation chamber.
Further, the top of the central guide cylinder is 100-150 mm below the liquid level, the top of the feed inlet of the evaporation chamber is 200-400 mm below the liquid level, and the top of the central guide cylinder is higher than the top of the feed inlet of the evaporation chamber.
Furthermore, the central guide cylinder is laterally provided with an oblique notch, and the included angle between the oblique notch and the vertical direction is 50-80 degrees.
Further, the central guide cylinder is a cylindrical inner cylinder, and the diameter of the central guide cylinder accounts for 70-80% of the inner diameter of the evaporation chamber; the height of the central guide cylinder is 1.5-3 times of the diameter of the feed inlet; and a circular hole is formed in the wall surface of the central guide cylinder, which is opposite to the direction of the feed inlet of the evaporation chamber, and the aperture is 10-80 mm.
Furthermore, the feed inlet of the evaporation chamber is arranged below the liquid level and is opposite to the feed inlet of the evaporation chamber, and the central guide cylinder is arranged.
Further, the elutriation legs are also provided with an internal circulation elutriation pipe, a lower elutriation water inlet and a salt discharge port positioned at the upper part of the lower elutriation water inlet;
the inner circulation elutriation pipe is provided with a second circulating pump, the upper opening of the inner circulation elutriation pipe is connected to the upper parts of the elutriation legs, and the lower opening of the inner circulation elutriation pipe is connected to the lower parts of the elutriation legs;
the salt discharge port is arranged above the lower elutriation water inlet, and the lower elutriation water inlet and the salt discharge port are both arranged below the joint of the lower port of the internal circulation elutriation pipe and the elutriation leg;
preferably, the distance between the upper opening of the internal circulation elutriation pipe and the tops of the elutriation legs is 100-400 mm, and the lower opening of the internal circulation elutriation pipe is 100-400 mm above the salt discharge opening.
Furthermore, the lower circulating pipe is connected to the lower side of the conical hopper of the evaporation chamber, is connected with the wall surface of the evaporation chamber and does not extend into the evaporation chamber; the upper circulating pipe is radially connected with the straight section of the evaporation chamber, is connected with the wall surface of the evaporation chamber and does not extend into the evaporation chamber.
The ideal condition during operation is that the feed liquid is heated and then enters the evaporation chamber, and can be uniformly distributed on the liquid level, so that the sectional area of the whole liquid level can be fully utilized, and the supersaturation degree of the flash evaporated feed liquid is uniformly released.
In the invention, raw water enters the evaporative crystallization device from the lower circulating pipe, is mixed with internal feed liquid, and enters the heating chamber through the circulating pump. The heating chamber is heated by saturated steam, the steam is condensed into water, and latent heat is transferred to the feed liquid. The feed liquid after heat exchange enters the evaporation chamber through the upper circulating pipe, and the feeding is radial. The liquid level in the evaporation chamber is slightly higher than the feed inlet and is shown by the dotted line in figure 2. The feed inlet is opposite to the central guide shell, one part of feed liquid enters the evaporation chamber and flows to the inner walls along the guide shell, and the other part of feed liquid flows to the central part of the guide shell from the small hole. Therefore, the evaporation chamber can uniformly distribute the feed liquid on the peripheral inner wall or the central part, so that the sectional area of the whole liquid surface is fully utilized, and the supersaturation degree of the flash evaporated feed liquid is uniformly released. When the flash evaporation device operates, the liquid level height is controlled, the feed inlet is close to the liquid level, the situation that the fed materials can flow to the liquid level quickly can be guaranteed, and flash evaporation is achieved. Similarly, the top end of the central guide shell is slightly lower than the liquid level, so that the liquid can be uniformly distributed and can rapidly flow to the liquid level for flash evaporation.
The conventional washing legs are washed with external raw water or steam condensate, and if the amount of crystallized salt impurities is increased, the amount of washing liquid required is increased. The increase of elutriation liquid can reduce the temperature of the material liquid in the evaporation chamber, and influence the evaporation. The invention is characterized in that the upper part and the lower part of the washing leg are respectively provided with a connector, and the feed liquid at the upper part is pumped to the lower part by a second circulating pump, thus forming an internal circulation inside the washing leg. The feed liquid inside the evaporation chamber was only pumped regardless of the pump flow rate without additional introduction of external elutriation liquid. The inner part of the washing leg is in a strong stirring state by utilizing the internal circulation, so that the crystal salts are rubbed with each other to scrub off impurities adhered on the crystal salts. Then a small amount of external elutriation liquid is introduced through an elutriation port at the bottom, and the impurities washed away are flushed back to the evaporation chamber and finally discharged through mother liquor. Thus not only ensuring the purity of the crystallized salt product, but also reducing the energy consumption brought by elutriation.
The invention also provides a method for treating wastewater by using the high-salinity high-organic-matter wastewater evaporative crystallization anti-scaling treatment device, which comprises the following steps of:
1) the method comprises the following steps that salt-containing wastewater enters a primary pretreatment system for evaporative crystallization, and a medicament capable of removing magnesium ions is added into the primary pretreatment system to reduce the magnesium hardness of the salt-containing wastewater;
2) the salt-containing wastewater after the primary pretreatment enters a secondary pretreatment system, and calcium chloride or sodium sulfate is added into the secondary pretreatment system according to the proportion of calcium ions and sulfate ions to form calcium sulfate crystal seeds;
3) the salt-containing wastewater after the secondary pretreatment enters an evaporation crystallizer through a lower circulating pipe, and mother liquor is quantitatively discharged out to control the content of impurities such as organic matters in the system not to exceed the standard and maintain a certain concentration of calcium sulfate crystal seeds in the evaporation crystallizer;
4) discharging the solid out of the discharged mother liquor through clarification and dehydration, and returning part of filtrate to the evaporation crystallizer for recycling;
5) and washing and purifying the saturated and separated crystal salt by washing legs to form a high-purity salt product.
Further, the concentration of the calcium sulfate seed crystal maintained in the step 3) is 15-40 g/L.
The first-stage pretreatment in the above method is a treatment method commonly used in the prior art, and the used reagents are also reagents commonly used by those skilled in the art, and are not described herein again.
According to the invention, calcium ions and sulfate ions existing in the wastewater are utilized to form calcium sulfate crystal seeds, so that on one hand, the calcium sulfate crystal seeds are completely removed without adding a medicament, thereby saving the cost, and on the other hand, a certain calcium sulfate concentration is maintained in the system, and calcium and magnesium scaling can be prevented.
The invention has the following beneficial effects:
the central guide cylinder is arranged in the evaporation chamber, so that the feeding materials can be uniformly distributed on the inner wall and the center of the whole evaporation chamber, a uniform boiling surface is provided, the boiling of the whole section in the crystallizer is very mild, the preferential boiling possibility does not exist at any specific part of the container, the local explosion nucleation of one or more points is avoided, the formation of superfine crystals is avoided, and the salt bar formed on the wall surface is also prevented from blocking equipment. Compared with the prior art, the device for treating the wastewater can ensure that the feed liquid is uniformly distributed in the evaporation chamber, the purity of the finally obtained crystallized salt can reach more than 99 percent, the cleaning period of the device is greatly prolonged and can reach more than 6 months, and the water loss can be reduced by more than 60 percent in the process of cleaning the crystallized salt.
Drawings
FIG. 1 is a schematic diagram of a prior art evaporative crystallization apparatus;
FIG. 2 is a schematic structural diagram of an apparatus for antiscaling by evaporative crystallization for high-salinity high-organic wastewater in example 1 of the present invention;
FIG. 3 is a schematic structural view of an apparatus for antiscaling by evaporative crystallization for high-salinity high-organic wastewater in example 2 of the present invention;
FIG. 4 is a schematic structural diagram of an evaporation chamber in the apparatus for antiscaling by evaporative crystallization of high-salinity high-organic wastewater according to example 1 of the present invention.
Detailed Description
In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings.
The above-described scheme is further illustrated below with reference to specific examples. It should be understood that these examples are for illustrative purposes and are not intended to limit the scope of the present invention. The conditions used in the examples may be further adjusted according to the specific product, and the conditions used in the experiments are not generally indicated.
Materials, reagents and the like used in the following examples are commercially available.
The invention provides a device and a method for carrying out evaporation crystallization and scale prevention treatment on high-salinity high-organic matter wastewater, and the specific embodiment is as follows.
Example 1
The invention provides a high-salinity high-organic matter wastewater evaporation crystallization anti-scaling treatment device, which comprises the following components in parts by weight in a figure 2-4: an evaporation chamber 1;
the upper end of the upper circulating pipe 10 is radially connected to the middle part or the middle lower part of the straight section of the evaporation chamber 1, and the lower end is connected with the outlet of the heating chamber 9;
the central guide cylinder 2 is arranged at the liquid level in the evaporation chamber 1, the upper part of the central guide cylinder 2 is provided with an oblique cut, the oblique cut is opposite to the direction of the evaporation chamber feed inlet 14, and a plurality of round holes are arranged right opposite to the evaporation chamber feed inlet 14;
a heating chamber 9, wherein the outlet of the heating chamber 9 is connected with the lower end of an upper circulating pipe 10;
a first circulating pump 8, the outlet of which is connected with the inlet of the heating chamber 9;
the upper end of the lower circulating pipe 3 is connected to the lower side of the conical hopper of the evaporation chamber 1, and the lower end of the lower circulating pipe is connected with the inlet of the first circulating pump 8;
the upper end of the washing leg 4 is connected with the bottom of the conical hopper of the evaporation chamber 1;
a mother liquor stewing device 13 which is arranged on the lower circulating pipe 3;
a feed inlet 12 positioned at the lower part of the mother liquor stewing device 13;
and a secondary steam pipe 11 installed on the top of the evaporation chamber 1.
The central guide cylinder is arranged in the evaporation chamber, so that the feeding materials can be uniformly distributed on the inner wall and the center of the whole evaporation chamber, a uniform boiling surface is provided, the boiling of the whole section in the crystallizer is very mild, the possibility of preferential boiling does not exist in any specific part of the container, the local explosion nucleation of one or more points is avoided, the formation of superfine crystals is avoided, and the formation of salt crust on the wall surface and the blockage of equipment are also prevented.
Further, the top of the central guide cylinder 2 is 100-150 mm below the liquid level, the top of the feed inlet 14 of the evaporation chamber is 200-400 mm below the liquid level, and the top of the central guide cylinder 2 is higher than the top of the feed inlet 14 of the evaporation chamber, so that the feed liquid can be uniformly distributed in the evaporation chamber 1 and can rapidly flow to the liquid level for flash evaporation.
Furthermore, the central guide cylinder 2 is laterally provided with an oblique notch, and the included angle between the oblique notch and the vertical direction is 50-80 degrees. If cylindrical, the feed will only reach the center through the orifice and the entire flow will be dominated by the outer annulus. The central guide shell 2 is provided with a cut in the lateral direction, and can flow to the middle part when the outer ring is fed, so that the material liquid in the center and around can be uniformly distributed.
Further, the central guide cylinder 2 is a cylindrical inner cylinder, and the diameter of the central guide cylinder accounts for 70-80% of the inner diameter of the evaporation chamber 1; the height of the central guide cylinder 2 is 1.5-3 times of the diameter of the feed inlet; the wall surface of the central guide cylinder 2, which faces the direction of the feed inlet 14 of the evaporation chamber, is provided with a round hole with the aperture of 10-80 mm.
Further, the feeding hole 14 of the evaporation chamber is below the liquid level and is opposite to the feeding hole 14 of the evaporation chamber, the central guide cylinder 2 is arranged, the feeding hole 14 of the evaporation chamber is below the liquid level, the liquid level height is controlled during operation, the feeding hole 14 of the evaporation chamber is close to the liquid level, the situation that the fed materials can rapidly flow to the liquid level can be guaranteed, and flash evaporation is achieved.
Further, the washing legs 4 are also provided with an internal circulation washing pipe 6, a lower washing water inlet 7 and a salt discharge port 5 positioned at the upper part of the lower washing water inlet 7;
the internal circulation elutriation pipe 6 is provided with a second circulating pump, the upper opening of the internal circulation elutriation pipe 6 is connected with the upper parts of the elutriation legs 4, and the lower opening of the internal circulation elutriation pipe 6 is connected with the lower parts of the elutriation legs 4;
the salt discharge port 5 is arranged above the lower elutriation water inlet 7, and the lower elutriation water inlet 7 and the salt discharge port 5 are both arranged below the joint of the lower port of the inner circulation elutriation pipe 6 and the elutriation legs 4;
preferably, the distance between the upper opening of the internal circulation elutriation pipe 6 and the top of the elutriation leg 4 is 100-400 mm, and the lower opening of the internal circulation elutriation pipe 6 is 100-400 mm above the salt discharge opening 5.
Compared with the washing leg without an internal circulation washing pipe, the device can save more than 60% of water resources, simultaneously, the purity of the crystal salt can reach more than 99%, and the water consumption and the system heat loss are reduced to a great extent.
Further, the lower circulating pipe 3 is connected to the lower side of the conical hopper of the evaporation chamber 1, is connected with the wall surface of the evaporation chamber 1 and does not extend into the evaporation chamber; the upper circulating pipe 10 is radially connected with the straight section of the evaporation chamber 1 and is connected with the wall surface of the evaporation chamber 1 without extending into the evaporation chamber, so that the inner part of the washing leg can be effectively prevented from being blocked.
Example 2
In this embodiment, the heating chamber 9 has a vertical structure, and has a small vertical floor space, and the rest is the same as that of embodiment 1.
Compared with the prior art, the wastewater treated by the embodiment 1-2 of the invention can ensure that the feed liquid is uniformly distributed in the evaporation chamber, the purity of the finally obtained crystallized salt can reach more than 99 percent, the cleaning period of the device is greatly prolonged and can reach more than 6 months, and the water loss can be reduced by more than 60 percent in the process of cleaning the crystallized salt.
The crystallization treatment of the wastewater is carried out by using the above apparatus, which is described in the following examples.
Example 3
The amount of the desulfurization wastewater of the power plant is 10m3And detecting the COD content of the product to be 300mg/L, the sodium chloride concentration to be 65g/L, the calcium ion concentration to be 2000mg/L, the magnesium ion concentration to be 5000mg/L and the sulfate ion concentration to be 4000 mg/L.
Step 1: the wastewater enters first-stage pretreatment, and calcium hydroxide is added to remove magnesium ions until the concentration is 80 mg/L;
step 2: the primary effluent enters secondary pretreatment, sodium sulfate is added to form calcium sulfate gypsum seed crystals, and the suspension concentration is 20 g/L;
and step 3: the secondary effluent enters the evaporative crystallization device in the embodiment 1 of the invention, the liquid level is controlled to be 300mm above the feed inlet, and 150mm above the top of the central guide shell;
and 4, step 4: the diameter of the central guide cylinder is 80% of the inner diameter of the evaporation chamber, the angle of the groove is 60 degrees, and the diameter of the opening facing the feeding direction is 25 mm;
and 5: elutriation internal circulation flow 4m3H, external elutriation liquor 1m3/h。
The obtained product is sodium chloride particles, wherein the purity is 99.1%, and the cleaning period of the device is 6 months.
Example 4
The desulfurization wastewater of the power plant has the water quantity of 5m3And detecting the COD content of the product to be 300mg/L, the sodium chloride concentration to be 55g/L, the calcium ion concentration to be 500mg/L, the magnesium ion concentration to be 300mg/L and the sulfate ion concentration to be 12000 mg/L.
Step 1: the wastewater enters first-stage pretreatment, and calcium hydroxide is added to remove the magnesium ions with the concentration of 80 mg/L;
step 2: the primary effluent enters secondary pretreatment, calcium chloride is added to form calcium sulfate gypsum crystal seeds, and the suspension concentration is 30 g/L;
and step 3: the secondary effluent enters the evaporative crystallization device in embodiment 2 of the invention, the liquid level is controlled to be 200mm above the feed inlet, and is 100mm above the top of the central guide shell;
and 4, step 4: the diameter of the central guide cylinder is 80% of the inner diameter of the evaporation chamber, the angle of the groove is 70 degrees, and the diameter of the opening facing the feeding direction is 20 mm;
and 5: elutriation internal circulation flow 2m3H, external elutriation liquor 0.5m3/h。
The obtained product is sodium chloride particles, wherein the purity is 99.3%, and the cleaning period of the device is 6 months.
Comparative example 1
The evaporative crystallization device adopts a device in the prior art, and is shown in the attached figure 1. The remaining conditions were the same as in inventive example 1.
The obtained product is sodium chloride particles, wherein the purity is 97.2%, and the cleaning period of the device is 4 months.
Taking example 3 and comparative example 1 as an example, the device for preventing scale of evaporative crystallization of high-salinity high-organic wastewater provided by the invention is illustrated in comparison with the evaporative crystallization device in the prior art, and the parameters in the operation process are shown in table 1.
TABLE 1
| Comparative example 1 | Example 1 | |
| Seed crystal concentration at the inner wall of the evaporation chamber | 8g/L | 18g/L |
| Seed concentration in the middle of the evaporation chamber | 16g/L | 16g/L |
| Elutriation liquor flow | 3m3/h | 1m3/h |
| Purity of sodium chloride | 97.2％ | 99.1％ |
| Sodium chloride particle diameter/mm | 0.1～0.3 | 0.4～0.6 |
| Device cleaning cycle | 4 months old | 6 months old |
As can be seen from the table above, the seed crystal concentration at the inner wall of the evaporation chamber and the seed crystal concentration in the middle of the evaporation chamber of the high-salinity high-organic-matter wastewater evaporation crystallization anti-scaling treatment device provided by the invention have the advantages that the difference is not large, the uniform distribution of the feed liquid is basically realized, the purity of the prepared sodium chloride is high, the using amount of the elutriation liquid is small, and the cleaning period of the device is long.
In conclusion, the central guide flow cylinder is arranged in the evaporation chamber, so that the feeding materials can be uniformly distributed on the inner wall and the center of the whole evaporation chamber, a uniform boiling surface is provided, the boiling of the whole section in the crystallizer is very mild, the possibility of preferential boiling does not exist in any specific part of the container, the local explosion nucleation of one or more points is avoided, the formation of ultrafine crystals is avoided, and the salt crust formed on the wall surface is prevented from blocking equipment. The washing legs are provided with an internal circulation washing pipeline, and the feed liquid is utilized to carry out internal disturbance, so that the crystal salt is scrubbed mutually, and impurities adhered to the surface are washed away. And the elutriation liquid at the bottom is used for flushing the fallen impurities back to the inside of the evaporation chamber, so that the purity of the discharged crystal salt is ensured to meet the requirement. This can provide high-intensity washing in the case where the crystal grain size is too fine, and can effectively reduce the amount of external elutriation liquid used, reducing energy consumption. According to the invention, calcium ions and sulfate ions existing in the wastewater are utilized to form calcium sulfate crystal seeds, so that on one hand, the calcium sulfate crystal seeds are completely removed without adding a medicament, thereby saving the cost, and on the other hand, a certain calcium sulfate concentration is maintained in the system, and calcium and magnesium scaling can be prevented. The device for the evaporation crystallization and scale prevention treatment of the high-salinity high-organic-matter wastewater is simple in structure, the uniform distribution of feed liquid in an evaporation chamber is realized, and the problems of scaling, undersize crystallization, low crystallization purity and the like caused in the evaporation crystallization process are effectively prevented.
The experiments are only preferred examples of the present invention and are not intended to limit the scope of the present invention. It should be noted that modifications and adaptations may occur to those skilled in the art without departing from the principles of the present invention and should be considered within the scope of the present invention.
Claims (7)
1. The utility model provides a high organic matter waste water evaporation crystallization anti fouling processing apparatus which characterized in that includes: an evaporation chamber;
the upper end of the upper circulating pipe is radially connected to the middle part or the middle-lower part of the straight section of the evaporation chamber, and the lower end of the upper circulating pipe is connected with an outlet of the heating chamber;
the upper part of the central guide cylinder is provided with an oblique cut which is opposite to the direction of the feed inlet of the evaporation chamber and is provided with a plurality of round holes right facing the feed inlet of the evaporation chamber;
the outlet of the heating chamber is connected with the lower end of the upper circulating pipe;
the outlet of the first circulating pump is connected with the inlet of the heating chamber;
the upper end of the lower circulating pipe is connected to the lower side of the conical hopper of the evaporation chamber, and the lower end of the lower circulating pipe is connected with the inlet of the first circulating pump;
the upper end of the washing leg is connected with the bottom of the conical hopper of the evaporation chamber;
the mother liquid standing device is arranged on the lower circulating pipe;
the feed inlet is positioned at the lower part of the mother liquid standing device;
a secondary steam pipe installed on the top of the evaporation chamber;
the top of the central guide cylinder is 100-150 mm below the liquid level, the top of the feed inlet of the evaporation chamber is 200-400 mm below the liquid level, and the top of the central guide cylinder is higher than the top of the feed inlet of the evaporation chamber;
the central guide cylinder is laterally provided with an oblique notch, and the included angle between the oblique notch and the vertical direction is 50-80 degrees;
the central guide cylinder is a cylindrical inner cylinder, and the diameter of the central guide cylinder accounts for 70-80% of the inner diameter of the evaporation chamber; the height of the central guide cylinder is 1.5-3 times of the diameter of the feed inlet; and a circular hole is formed in the wall surface of the central guide cylinder, which is opposite to the direction of the feed inlet of the evaporation chamber, and the aperture is 10-80 mm.
2. The evaporative crystallization anti-scaling treatment device for high-salinity high-organic wastewater according to claim 1, wherein the central guide cylinder is arranged below the liquid level and opposite to the feed inlet of the evaporation chamber.
3. The evaporative crystallization antiscaling treatment device for high-salinity high-organic wastewater according to claim 1, wherein the elutriation legs are further provided with an internal circulation elutriation pipe, a lower elutriation water inlet and a salt discharge port located at an upper portion of the lower elutriation water inlet;
the inner circulation elutriation pipe is provided with a second circulating pump, the upper opening of the inner circulation elutriation pipe is connected to the upper parts of the elutriation legs, and the lower opening of the inner circulation elutriation pipe is connected to the lower parts of the elutriation legs;
the salt discharge port is arranged above the lower elutriation water inlet, and the lower elutriation water inlet and the salt discharge port are both arranged below the joint of the lower port of the internal circulation elutriation pipe and the elutriation leg.
4. The evaporative crystallization antiscaling treatment device for high-salinity high-organic wastewater according to claim 3, wherein the upper opening of the internal circulation elutriation pipe is 100-400 mm away from the tops of the elutriation legs, and the lower opening of the internal circulation elutriation pipe is 100-400 mm above the salt discharge opening.
5. The evaporative crystallization anti-scaling treatment device for high-salinity high-organic wastewater as claimed in claim 1, wherein the lower circulation pipe is connected to the lower side of the conical hopper of the evaporation chamber, is connected with the wall surface of the evaporation chamber and does not extend into the conical hopper; the upper circulating pipe is radially connected with the straight section of the evaporation chamber, is connected with the wall surface of the evaporation chamber and does not extend into the evaporation chamber.
6. A method for treating wastewater by using the evaporative crystallization anti-scaling treatment device for high-salinity high-organic wastewater as claimed in any one of claims 1 to 5, which is characterized by comprising the following steps:
1) the method comprises the following steps that salt-containing wastewater enters a primary pretreatment system for evaporative crystallization, and a medicament capable of removing magnesium ions is added into the primary pretreatment system to reduce the magnesium hardness of the salt-containing wastewater;
2) the salt-containing wastewater after the primary pretreatment enters a secondary pretreatment system, and calcium chloride or sodium sulfate is added into the secondary pretreatment system according to the proportion of calcium ions and sulfate ions to form calcium sulfate crystal seeds;
3) the salt-containing wastewater after the secondary pretreatment enters an evaporation crystallizer through a lower circulating pipe, and mother liquor is quantitatively discharged out to control the content of organic impurities in the system not to exceed the standard and maintain a certain concentration of calcium sulfate crystal seeds in the evaporation crystallizer;
4) discharging the solid out of the discharged mother liquor through clarification and dehydration, and returning part of filtrate to the evaporation crystallizer for recycling;
5) and washing and purifying the saturated and separated crystal salt by washing legs to form a high-purity salt product.
7. The method for treating wastewater by using the evaporative crystallization antiscaling treatment device for high-salinity high-organic wastewater according to claim 6, wherein the concentration of the calcium sulfate seed crystal maintained in the step 3) is 15-40 g/L.
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