Device and method for producing salt
Through the combination device of VI salt evaporation tank and separator, the problem of difficult to reduce the content of solid impurities in the salt slurry is solved, and the quality of salt products and the thermal utilization rate are improved.
Patent Information
- Application Number
- CN202411822071.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-11
- Publication Date
- 2025-03-11
AI Technical Summary
The prior art is difficult to effectively reduce the content of solid impurities in the salt slurry, affecting the quality of the salt product.
The combination device of the VI salt evaporation tank and the separator is used to evaporate the brine to obtain salt, solid impurities and mother liquor, and the material is separated by the separator to obtain solid impurities, mother liquor and salt slurry. By eliminating the mother liquor, the content of Na2SO4 in the VI salt evaporation tank is controlled to avoid the generation of calcium Glauber's salt complex salt.
It significantly improves the quality of salt, reduces the content of solid impurities, improves the quality and heat utilization of salt, and reduces the energy consumption of the system.
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Figure CN119588002A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of salt production, and in particular to a device and method for producing salt. Background Art
[0002] The majority of domestic well salt brine is Glauber's salt brine, and many manufacturers use brine purification and non-brine purification. As we all know, brine purification can achieve sufficient brine preheating, greatly improve heat utilization, and produce high-quality products, but brine purification requires large investment and high operating costs. Faced with the reality of high quality but low price, many salt companies do not use brine purification. For non-purified Glauber's salt brine, its multi-effect vacuum salt production methods mainly include the following:
[0003] One is to ensure the salt quality by discharging a large amount of mother liquor to make the Na2SO4 in the evaporation tank unsaturated. Since the solubility of Na2SO4 in saturated NaCl solution is not high, a large amount of mother liquor must be discharged (especially for medium and high nitrate brine), which will bring out a large amount of heat and cause energy waste. Therefore, the consumption is very high, and the salt quality cannot necessarily be guaranteed in actual production.
[0004] The second method is to ensure the salt quality by discharging the old brine after washing the salt. Since there is no need to control the precipitation of mirabilite in the tank, the mother liquor discharge is small, so the heat utilization rate is much higher than that of method 1. Since there is no need to purify the brine, the investment is small and the cost is low, but the brine consumption is high and the saltpeter resource is seriously wasted. What is more disadvantageous is that the long-term circulation and injection of salt-containing saltpeter wastewater can cause the Na2SO4 content in the brine to increase, thus affecting the salt quality and consumption.
[0005] The third method is to use the reverse dissolution property of Na2SO4 above 17.9℃ to heat the high-nitrate brine discharged from salt production to about 100℃, add salt mud to the preheated brine or put it into the nitrate evaporation tank for evaporation and concentration (so it is also called salting out method), so that the old brine that is not saturated with NaCl after heating becomes a saturated solution or a nearly saturated solution. + Due to the common ion effect, Na2SO4 is precipitated and saltpeter is separated. The mother liquor after saltpeter extraction (also called refined brine) is sent back to the salt making system to produce salt. For non-purified brine, salt mud, which was a waste in the past, is used as the raw material for salting out, which not only precipitates saltpeter, but also increases the NaCl content of refined brine. At the same time, it also makes it possible to preheat the high-temperature brine that was not applicable in the past (brine preheating can greatly improve the thermal utilization rate, but the original brine is easy to scale at high temperature and cannot be used, while the old brine is not easy to scale). In addition, since there is no need to discharge the mother liquor from the salt system, the heat loss is small, so the consumption is much lower than that of traditional multi-effect evaporation.
[0006] Comparison of non-purified brine production processes
[0007] Method 1: Theoretically, controlling the evaporation rate and the amount of mother liquor discharged can ensure the composition of the mother liquor in the tank, and also ensure the quality of the product. However, in actual production, due to changes in process parameters, the salt quality is very unstable. When it is good, it can produce high-grade salt, but when it is bad, it cannot even produce secondary salt, and the consumption is very high.
[0008] Method 2: Optimize the design of the salt washing system, control the amount of brine, and produce high-quality salt without any problems, and the consumption is also lower than that of Method 1. Example: The No. 1 line of a salt enterprise adopts Method 1 four-effect production, with a steam consumption of 1.2t / t salt. In 2018, due to poor salt quality and unsalable products, it was forced to stop production for more than half a year. After the transformation according to Method 2, the salt quality was greatly improved to above the high-quality salt, and the steam consumption was reduced to 1t / t salt.
[0009] Method three: By extending the salt washing time and increasing the amount of brine added, the salt quality is basically the same as method two, but the consumption is more than 10% lower. It not only increases production but also saves energy, with obvious advantages. Many salt companies have adopted this method for production.
[0010] In summary, as long as the design is reasonable and the operation is proper, non-purified brine can produce high-grade salt. Generally, the main content of NaCl is about 99.2%-99.3%, which can basically meet the needs of most customers. However, with the increasingly fierce market competition and the continuous improvement of customer requirements, it is necessary to improve the quality of salt products to meet the needs of some customers for high-quality salt. Since the brine is not purified, it is difficult to improve the quality even a little after reaching a certain level.
[0011] To summarize the market demand, the customers of high-quality salt are mainly special salt manufacturers, and their quality requirements for high-quality salt are as low as possible SO4 2- Generally speaking, no matter how good the quality of raw salt is, it needs to be refined twice in the production process of special salt users. The removal of metal ions such as calcium and magnesium is easy and cost-effective, but the removal of SO4 2- It is very difficult, so the key to improving the quality of salt is to reduce SO4 2- The content.
[0012] Usually, the main impurities of mirabilite-type brine are Na2SO4, CaSO4, and MgSO4. In the production process, the solubility of MgSO4 is relatively large, and it generally does not saturate and precipitate, while the solubility of CaSO4 is relatively small and has reverse dissolution characteristics, and it is very easy to precipitate in supersaturation. When solid mirabilite precipitates in the solution, the two will combine to form calcium mirabilite (CaSO4·Na2SO4) double salt. Solid calcium sulfate, calcium mirabilite, mirabilite and soluble Na2SO4, MgSO4, etc. are the main impurities that affect the quality of salt. According to the principle of crystallography, crystals generally grow on the nuclei of the same substance. Therefore, the main reason for the poor quality of salt is that solid impurities are mixed with NaCl crystals, and secondly, soluble impurities are attached to the surface of NaCl crystals. Therefore, reducing the content of solid impurities in salt slurry can improve product quality. However, how to reduce the content of solid impurities in salt slurry is a technical problem that the prior art needs to solve. Summary of the invention
[0013] We found that the salt quality can be improved by washing, and the way to remove or reduce impurities is to wash the salt slurry through a reverse flotation washer. The working principle is twofold: first, when brine with low soluble impurity content is in contact with the salt slurry for a certain period of time, the Na2SO4 crystals are dissolved back, and the high concentrations of Na2SO4, MgSO4, etc. are diluted or replaced; second, NaCl crystal particles are regular and have a large particle size, so the sedimentation rate is fast, while calcium sulfate, calcium glauber's salt, and thenardite have small particles, irregular shapes, or both, which makes the sedimentation rate slow. Therefore, the difference in sedimentation rate can be used to separate salt and solid impurities. Practice has proved that optimized salt washing system design and careful operation can ensure the production of superior salt, but the efficiency of sedimentation separation cannot reach 100%, and there is always a very small amount of solid impurities entering the salt product, which restricts the further improvement of product quality.
[0014] The purpose of the present invention is to overcome the above technical deficiencies, provide a device and method for producing salt, and solve the technical problem of how to reduce the content of solid impurities in salt slurry in the prior art.
[0015] In order to achieve the above technical purpose, the technical solution of the present invention provides a device for producing salt, including a VI effect salt evaporator and a separator; the VI effect salt evaporator is used to evaporate brine to obtain salt, solid impurities and mother liquor, and the mother liquor is a mother liquor containing more sodium sulfate; the feed port of the separator is connected to the discharge port of the VI effect salt evaporator, and the separator is used to separate the material to obtain solid impurities, mother liquor and salt slurry.
[0016] In any embodiment, it also includes a V-effect salt evaporation tank, the feed port of the V-effect salt evaporation tank is connected to the discharge port of the separator, and the V-effect salt evaporation tank is used to evaporate the mother liquor; if the mother liquor is insufficient, part of the brine needs to be supplemented to evaporate in the V-effect salt evaporation tank.
[0017] In any embodiment, a first salt collecting box is further included, wherein a feed port of the first salt collecting box is connected to a discharge port of the V-effect salt evaporation tank, and the first salt collecting box is used to collect salt discharged from the V-effect salt evaporation tank.
[0018] In any embodiment, a second salt collecting box is further included, wherein the feed port of the second salt collecting box is connected to the discharge port of the VI effect salt evaporation tank, and the second salt collecting box is used to collect salt discharged from the VI effect salt evaporation tank.
[0019] In any embodiment, it further comprises a first flotation device, wherein the first flotation device is connected to a discharge port on a side of the second salt collecting box, and the first flotation device is used for preliminarily cleaning the salt in the second salt collecting box.
[0020] In any embodiment, a second flotation device is further included, wherein a feed port of the second flotation device is connected to a discharge port of the first flotation device, and the second flotation device is used to clean the salt in the second salt collecting box again.
[0021] In any embodiment, the method further comprises a centrifuge, wherein the centrifuge is connected to the second flotation device and is used for dehydrating the washed salt.
[0022] In addition, the present invention also provides a method for producing salt, comprising the following steps:
[0023] Evaporating the brine in a VI effect salt evaporator to obtain salt, solid impurities and mother liquor;
[0024] The material is separated into solid impurities, mother liquor and salt slurry through a separator.
[0025] In any embodiment, part of the mother liquor is transferred from the separator to a V-effect salt evaporation tank for evaporation.
[0026] Compared with the prior art, the beneficial effects of the present invention include: the salt production device proposed by the present invention comprises a VI effect salt evaporation tank and a separator; the VI effect salt evaporation tank is used to evaporate brine to obtain salt and mother liquor; the separator is connected to the VI effect salt evaporation tank, and the separator is used to separate the material to obtain solid impurities, mother liquor and salt slurry, and the mother liquor contains more sodium sulfate; a separator is arranged on the circulation pipe of the final effect evaporation tank and the VI effect salt evaporation tank, and the mother liquor nearly saturated with Na2SO4 is discharged through the separator, and at the same time, brine will continue to enter the VI effect salt evaporation tank, and the Na2SO4 in the VI effect salt evaporation tank is always unsaturated, so that the VI effect salt evaporation tank does not precipitate salt, and since there is no precipitation of solid sodium sulfate in the VI effect salt evaporation tank, no calcium sodium sulfate complex salt is produced, so that the quality of the salt is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1It is a schematic diagram of the structure of the salt production device of Example 1 of the present invention.
[0028] Figure 2 It is a structural block diagram of the salt production device according to Example 1 of the present invention.
[0029] Explanation of the accompanying reference numerals: 1. VI effect salt evaporation tank; 2. separator; 3. V effect salt evaporation tank; 4. first salt collecting box; 5. second salt collecting box; 6. first flotation device; 7. second flotation device; 8. centrifuge. DETAILED DESCRIPTION
[0030] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of the particular range. The range defined in this way can be inclusive or exclusive of the end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 60 to 120 and 80 to 110 is listed for a particular parameter, it is understood that a range of 60 to 110 and 80 to 120 is also expected. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4 and 5 are listed, the following ranges can all be expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4 and 2 to 5. In the present application, unless otherwise specified, the numerical range "a to b" represents an abbreviation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.
[0031] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.
[0032] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).
[0033] This specific embodiment provides a salt production device, including a VI salt evaporation tank and a separator; the VI salt evaporation tank is used to evaporate brine to obtain salt, solid impurities and mother liquor; the separator is connected to the VI salt evaporation tank, and the separator is used to separate the material to obtain solid impurities, mother liquor and salt slurry. The mother liquor is a mother liquor containing more mirabilite.
[0034] In some embodiments, a V-effect salt evaporator is also included, and the V-effect salt evaporator is connected to the separator, and the V-effect salt evaporator is used to evaporate the mother liquor and the supplemented brine. The mother liquor discharged from the final VI-effect salt evaporator enters the previous V-effect salt evaporator, which is equivalent to countercurrent feeding, has little effect on system consumption, and can produce ordinary salt and high-quality salt in one set of salt-making equipment at the same time.
[0035] In some embodiments, a first salt collecting box is further included, wherein the feed port of the first salt collecting box is connected to the discharge port of the V-effect salt evaporation tank, and the first salt collecting box is used to collect salt discharged from the V-effect salt evaporation tank.
[0036] In some embodiments, a second salt collecting box is further included, wherein the feed port of the second salt collecting box is connected to the discharge port of the VI effect salt evaporation tank, and the second salt collecting box is used to collect salt discharged from the VI effect salt evaporation tank.
[0037] In some embodiments, a first flotation device is further included, wherein the first flotation device is connected to a discharge port on a side of the second salt collecting box, and the first flotation device is used for preliminarily cleaning the salt in the second salt collecting box.
[0038] In some embodiments, a second flotation device is further included, wherein a feed port of the second flotation device is connected to a discharge port of the first flotation device, and the second flotation device is used to clean the salt in the second salt collecting box again.
[0039] In some embodiments, a centrifuge is further included, and the centrifuge is connected to the second flotation device 7, and the centrifuge is used to dehydrate the washed salt.
[0040] This specific embodiment also proposes a method for producing salt, comprising the following steps:
[0041] Evaporating the brine in a VI effect salt evaporator to obtain salt, solid impurities and mother liquor;
[0042] The materials are separated by a separator to obtain solid impurities, mother liquor and salt slurry;
[0043] A portion of the mother liquor is transferred from the separator to a V-effect salt evaporation tank for evaporation.
[0044] By removing the mother liquor, the content of Na2SO4 in the VI effect salt evaporator is controlled, so that the VI effect salt evaporator does not precipitate salt. Since there is no precipitation of solid Glauber's salt in the VI effect salt evaporator, there is no production of calcium Glauber's salt complex salt. At the same time, the mother liquor discharged through the separator brings out a large amount of solid impurity CaSO4, and reduces the content of soluble impurities such as MgSO4, which greatly improves the salt washing effect and greatly improves the quality of the salt obtained from the VI effect salt evaporator. The mother liquor discharged from the final VI effect salt evaporator enters the V effect salt evaporator in front, which is equivalent to countercurrent feeding, which has little effect on system consumption, and can produce ordinary salt and high-quality salt in one set of salt making equipment at the same time.
[0045] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.
[0046] In the present invention, reference is made to “some embodiments”, “this embodiment”, examples, etc., which describe a subset of all possible embodiments, but it can be understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.
[0047] If similar descriptions of "first / second" appear in the application documents, the following instructions are added. In the following description, the terms "first\second\third" involved are merely used to distinguish similar objects and do not represent a specific ordering of the objects. It can be understood that "first\second\third" can be interchanged in a specific order or sequence where permitted, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein.
[0048] In this embodiment, the term "and / or" is merely a description of the association relationship between associated objects, indicating that three relationships may exist. For example, object A and / or object B may represent three situations: object A exists alone, object A and object B exist at the same time, and object B exists alone.
[0049] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained commercially.
[0050] It should be noted that the various components of the following embodiments, such as the VI effect salt evaporation tank, the separator and the V effect salt evaporation tank, are connected by connecting pipes. Steam and condensed water are the same as the traditional process, the IV effect secondary steam goes to the V effect heating chamber, and the V effect secondary steam goes to the VI effect heating chamber. The salt discharge and subsequent processes from I to V effects are the same as the traditional process (to the old salt collecting box, salt washing, dehydration, drying), and the VI effect salt slurry (high-quality salt) is separately discharged, washed, and dehydrated.
[0051] Example 1
[0052] Combination Figure 1-2 This embodiment proposes a salt production device, including a VI effect salt evaporation tank 1 and a separator 2; the VI effect salt evaporation tank 1 is used to evaporate brine to obtain salt, solid impurities and mother liquor, and the mother liquor is a mother liquor containing more sodium sulfate; the separator 2 is connected to the VI effect salt evaporation tank 1, and the separator 2 is used to separate the material to obtain solid impurities, mother liquor and salt slurry.
[0053] On the basis of the above embodiment, the present embodiment further comprises a V-effect salt evaporation tank 3, which is connected to the separator 2 and is used to evaporate the mother liquor and the supplemented brine. If the mother liquor is insufficient, part of the brine needs to be supplemented to evaporate in the V-effect salt evaporation tank, and the mother liquor discharged from the last VI-effect salt evaporation tank 1 enters the front V-effect salt evaporation tank 3, which is equivalent to countercurrent feeding, which has little effect on system consumption, and can produce ordinary salt and high-quality salt in one set of salt making equipment at the same time.
[0054] On the basis of the above embodiment, the present embodiment further comprises a first salt collecting box 4, the feed port of the first salt collecting box 4 is connected to the discharge port of the V-effect salt evaporation tank 3, and the first salt collecting box 4 is used to collect the salt discharged from the V-effect salt evaporation tank 3. It can be understood that the feed port of the first salt collecting box can also be connected to the discharge port of the I-IV-effect salt evaporation tank in the prior art.
[0055] On the basis of the above embodiment, this embodiment further comprises a second salt collecting box 5 , the feed port of the second salt collecting box 5 is connected to the discharge port of the VI effect salt evaporation tank 1 , and the second salt collecting box 5 is used to collect the salt discharged from the VI effect salt evaporation tank 1 .
[0056] On the basis of the above embodiment, this embodiment further comprises a first flotation device 6 , which is connected to the discharge port on the side of the second salt collecting box 5 , and is used for preliminarily cleaning the salt in the second salt collecting box 5 .
[0057] On the basis of the above embodiment, this embodiment further comprises a second flotation device 7, the feed port of the second flotation device 7 is connected to the discharge port of the first flotation device 6, and the second flotation device 7 is used to clean the salt in the second salt collecting box again.
[0058] On the basis of the above embodiment, this embodiment further comprises a centrifuge 8, wherein the centrifuge 8 is connected to the second flotation device 7, and the centrifuge 8 is used for dehydrating the washed salt.
[0059] This embodiment also proposes a method for producing salt by the above device, comprising the following steps:
[0060] Evaporating the brine in a VI effect salt evaporator to obtain salt, solid impurities and mother liquor;
[0061] The materials are separated by a separator to obtain solid impurities, mother liquor and salt slurry;
[0062] A portion of the mother liquor is transferred from the separator to a V-effect salt evaporation tank for evaporation.
[0063] The quality of the salt obtained from the VI effect salt evaporator and the V effect salt evaporator treated by the device and method of this embodiment is shown in Table 1 below.
[0064] Table 1 Example 1 The content of sulfate in the wet salt obtained by the VI effect salt evaporation tank and the V effect salt evaporation tank
[0065] Effect V VI effect Sulfate content (%) ≤0.4％ ≤0.15％
[0066] It can be seen from Table 1 that the salt prepared in this embodiment has higher quality and contains lower sulfate.
[0067] It should be noted that the sulfate in the above embodiments is mainly sodium sulfate, and also contains some calcium sulfate, magnesium sulfate, etc.
[0068] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.
Claims
1. A device for producing salt, characterized in that: It comprises a VI effect salt evaporation tank and a separator; the VI effect salt evaporation tank is used to evaporate brine to obtain salt, solid impurities and mother liquor; the feed port of the separator is connected with the discharge port of the VI effect salt evaporation tank, and the separator is used to separate the material to obtain solid impurities, mother liquor and salt slurry.
2. The salt production device according to claim 1, characterized in that It also includes a V-effect salt evaporation tank, the feed port of the V-effect salt evaporation tank is connected with the discharge port of the separator, and the V-effect salt evaporation tank is used to evaporate the mother liquor.
3. The salt production device according to claim 1, characterized in that It also includes a first salt collecting box, the feed port of the first salt collecting box is connected to the discharge port of the V-effect salt evaporation tank, and the first salt collecting box is used to collect salt discharged from the V-effect salt evaporation tank.
4. The salt production device according to claim 1, characterized in that It also includes a second salt collecting box, the feed port of the second salt collecting box is connected to the discharge port of the VI effect salt evaporation tank, and the second salt collecting box is used to collect salt discharged from the VI effect salt evaporation tank.
5. The salt production device according to claim 4, characterized in that It also includes a first flotation device, which is connected to the discharge port on the side of the second salt collecting box and is used for preliminarily cleaning the salt in the second salt collecting box.
6. The salt production device according to claim 5, characterized in that It also includes a second flotation device, the feed port of the second flotation device is connected to the discharge port of the first flotation device, and the second flotation device is used to clean the salt in the second salt collecting box again.
7. The salt production device according to claim 6, characterized in that It also includes a centrifuge, which is connected to the second flotation device and is used for dehydrating the washed salt.
8. A method for producing salt, characterized in that The following steps are involved: Evaporating the brine in a VI effect salt evaporator to obtain salt, solid impurities and mother liquor; The material is separated into solid impurities, mother liquor and salt slurry through a separator.
9. The method for producing salt according to claim 8, characterized in that The method also includes transferring part of the mother liquor from the separator to a V-effect salt evaporation tank for evaporation.