CN113184882A - System and method for denitration by-product potassium sulfate product by potassium chloride hydrothermal method - Google Patents
System and method for denitration by-product potassium sulfate product by potassium chloride hydrothermal method Download PDFInfo
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- CN113184882A CN113184882A CN202110482847.8A CN202110482847A CN113184882A CN 113184882 A CN113184882 A CN 113184882A CN 202110482847 A CN202110482847 A CN 202110482847A CN 113184882 A CN113184882 A CN 113184882A
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D5/00—Sulfates or sulfites of sodium, potassium or alkali metals in general
- C01D5/16—Purification
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D1/00—Oxides or hydroxides of sodium, potassium or alkali metals in general
- C01D1/04—Hydroxides
- C01D1/28—Purification; Separation
- C01D1/30—Purification; Separation by crystallisation
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D5/00—Sulfates or sulfites of sodium, potassium or alkali metals in general
- C01D5/004—Preparation in the form of granules, pieces or other shaped products
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F11/00—Compounds of calcium, strontium, or barium
- C01F11/20—Halides
- C01F11/24—Chlorides
- C01F11/32—Purification
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
- Y02P20/129—Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
Abstract
The invention relates to the technical field of chemical industry, and discloses a system and a method for denitration by a potassium chloride hydrothermal method and by-production of a potassium sulfate product, wherein the method comprises the following steps: the nanofiltration membrane unit receives dechlorinated light salt brine from an external potash device and conveys the dechlorinated light salt brine to the heat exchange unit for heat exchange, secondary gas condensate generated by the evaporation crystallization unit is conveyed to the heat exchange unit, heat exchange is carried out between the dechlorinated light salt brine and the secondary gas condensate in the heat exchange unit, the dechlorinated light salt brine after heat exchange is input to the evaporation crystallization unit for evaporation and concentration to obtain potassium sulfate crystals, waste heat recovery treatment is carried out on the secondary gas condensate after heat exchange, the potassium sulfate crystals are treated by the centrifugal separation unit and then enter the drying unit for drying to obtain qualified potassium sulfate products, and centrifugal mother liquor after centrifugal separation is output to the potash device for a secondary brine refining process. The invention effectively makes up the defects of the barium method denitration or calcium method denitration flow used in the current industrial production, and achieves the purposes of cost reduction and efficiency improvement.
Description
Technical Field
The invention relates to the technical field of chemical industry, in particular to a system and a method for denitration by a potassium sulfate product by a potassium chloride hydrothermal method.
Background
Removal of sulfate from solution is also known as denitration. In the production of the ionic membrane potash plant, the quality of potassium chloride refined brine has a determining effect on the service life and the power consumption of the ionic membrane, and the content of sulfate radicals is one of important indexes of the quality of the refined brine. In the electrolytic cell, the cations and sulfates in the refined brine form insoluble sulfate substances, which are deposited on the ion membrane, thereby causing a decrease in the current efficiency of electrolysis. The sulfate radical in the refined brine exceeds the standard for a long time, physical damage can be caused to the ionic membrane, the membrane resistance is increased, and the power consumption is increased.
Because the solubility of potassium sulfate in potassium chloride solution is low, and the solubility curves of potassium sulfate and potassium chloride are nearly parallel, the potassium sulfate can not be effectively separated by freezing crystallization, and therefore, the freezing denitration process commonly used in the production of 'ionic membrane sodium hydroxide' can not be used. At present, various production plants adopt a method of adding chemical reagents such as barium chloride, calcium sulfate and the like to remove sulfate radicals according to the principle of total amount control, but the methods all have certain defects, and the method specifically comprises the following steps:
(1) the barium method denitration, namely adding barium chloride to generate barium sulfate precipitate and then filtering to remove sulfate radical, has the following problems:
(a) the barium chloride has high toxicity, high transportation cost and high management difficulty, and the barium chloride solution has a complex preparation system, and needs to consider the collection of highly toxic dust and the labor protection of operators;
(b) barium chloride is a limited product, is expensive, and particularly has high production cost when the raw salt with high sulfate radical content is used;
(c) in the barium mud generated after denitration, partial barium chloride is remained, special treatment is needed, and the cost is high;
(2) the calcium method denitration, namely adding calcium chloride to generate calcium sulfate precipitate and then filtering to remove sulfate radical, has the following problems:
(a) calcium sulfate is easy to scale, and can cause blockage of pipelines and the like;
(b) the quality of the calcium chloride raw material can cause certain influence on a brine system;
(c) after calcium chloride is added, calcium ions in the system are increased, and the cost of calcium removal is increased;
(d) the method of pre-concentrating potassium sulfate by adopting a nanofiltration membrane and adding calcium chloride is improved, but the defects still exist.
Therefore, a sulfate radical removal process without introducing additional impurities and generating solid waste needs to be invented, so that the defects of the barium method denitration or calcium method denitration process used in the current industrial production are effectively overcome, and the aims of cost reduction and efficiency improvement are achieved.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: aiming at the problems, the invention provides a system and a method for denitration by a potassium chloride salt hydrothermal method and by-producing a potassium sulfate product, wherein the system and the method adopt a method of nanofiltration concentration, evaporative crystallization, centrifugal separation and drying to remove sulfate radicals and by-produce the potassium sulfate product; the centrifugal mother liquor is directly returned to the secondary brine refining process of the potash plant, so that the load of the primary brine refining process of the potash plant can be reduced.
The technical scheme adopted by the invention is as follows:
in one aspect, the invention provides a system for denitration by a potassium sulfate product by a potassium chloride hydrothermal method, comprising: the device comprises a nanofiltration membrane concentration unit, a heat exchange unit, an evaporative crystallization unit, a centrifugal separation unit and a drying unit, wherein the nanofiltration membrane concentration unit is connected to the evaporative crystallization unit through the heat exchange unit, and the evaporative crystallization unit, the centrifugal separation unit and the drying unit are sequentially connected; the nanofiltration membrane unit receives dechlorinated light salt brine from an external potash device and concentrates the dechlorinated light salt brine, concentrated liquid after concentration is conveyed to the heat exchange unit, secondary gas condensate generated by the evaporation crystallization unit is conveyed to the heat exchange unit, heat exchange is carried out between the concentrated liquid and the secondary gas condensate in the heat exchange unit, the concentrated liquid after heat exchange is input to the evaporation crystallization unit to carry out evaporation concentration to obtain potassium sulfate crystals, and the potassium sulfate crystals are treated by the centrifugal separation unit and then enter the drying unit to be dried to obtain qualified potassium sulfate products;
the evaporative crystallization unit comprises a circulating pump, a circulating heater, an evaporator and an MVR vapor recompression system, wherein the circulating heater, the circulating pump and the evaporator are circularly connected, one end of the MVR vapor recompression system is connected to the evaporator, and the other end of the MVR vapor recompression system is connected to the circulating heater; the evaporation temperature is controlled to be between 80 and 105 ℃, so that the investment is saved, and the energy consumption is reduced;
the heat exchange unit comprises a brine heater, the input end of the brine heater is respectively connected with the nanofiltration membrane concentration unit and the circulating heater, the first output end of the brine heater is connected to the evaporator, and the second output end of the brine heater is used for recovering secondary gas condensate after heat exchange.
Furthermore, the centrifugal separation unit comprises a thickener connected to the evaporator and a centrifuge connected to the drying unit, the thickener and the centrifuge are connected with each other, the thickener is used for thickening the taken out liquid of the potassium sulfate crystal, and the centrifuge is used for performing centrifugal separation on the thickened taken out liquid.
Further, still include the recovery unit, the recovery unit is connected on the centrifugation unit, the recovery unit is including mother liquor dashpot and the mother liquor pump that links together, the mother liquor dashpot is connected on the stiff ware, the mother liquor pump carries the centrifugation mother liquor in the mother liquor dashpot to the potash device and carries out the refined process of secondary salt water, can directly return the centrifugation mother liquor to the potash device through this recovery unit and carry out the refined process of secondary salt water, has reduced the load of the refined process of primary salt water in the conventional flow.
Further, the drying unit comprises an air flow dryer, a cyclone separator, a bag-type dust collector, a fan, an air heater and an air fan, the air flow dryer is connected to the centrifugal separation unit, the air flow dryer, the cyclone separator, the bag-type dust collector and the fan are sequentially connected, the air heater is connected to the air flow dryer, the air fan is connected to the air heater, and the air fan and the air heater are used for inputting hot air to the air flow dryer so as to dry potassium sulfate crystals.
Further, the nanofiltration membrane concentration unit comprises a nanofiltration membrane system connected to the brine heater.
In another aspect, the present invention provides a method for denitration by a potassium sulfate product by a potassium chloride hydrothermal method, comprising:
the temperature of dechlorinated light salt brine from a potash device is regulated, the dechlorinated light salt brine is input to a nanofiltration membrane concentration unit to be concentrated with sulfate radicals, permeate liquid generated after concentration returns to the potash device for salt dissolving, and concentrate liquid generated after concentration is input to a heat exchange unit;
exchanging heat between the concentrated solution and the secondary gas condensate from the evaporative crystallization unit in a heat exchange unit, allowing the concentrated solution subjected to heat exchange to enter the evaporative crystallization unit, separating out potassium sulfate in the concentrated solution in the evaporative crystallization unit after evaporative concentration, and allowing the separated potassium sulfate crystals to enter a centrifugal separation unit for centrifugal separation;
and (4) drying the potassium sulfate solid obtained after centrifugal separation in a drying unit to obtain a potassium sulfate product.
Further, the method further comprises the following steps: and centrifuging the potassium sulfate crystals to obtain centrifugal mother liquor, and returning the centrifugal mother liquor to a secondary brine refining process of the potash plant through a recovery unit.
Further, the method further comprises the following steps: and (4) performing waste heat recovery on the secondary gas condensate after heat exchange through a heat exchange unit.
Compared with the prior art, the beneficial effects of adopting the technical scheme are as follows:
the invention carries out sulfate radical concentration by a nanofiltration membrane system to obtain nitrate-rich brine, and then separates K from the nitrate-rich brine by means of evaporation crystallization2SO4The purpose of removing sulfate radicals is achieved through crystallization, impurities can be prevented from being introduced when chemicals are used, solid waste is not generated, the method is a green and environment-friendly technology, and cost reduction and efficiency improvement of a potash device can be realized.
The consumption of crude salt (KCl) for potassium hydroxide production is about: 1350kg/t KOH, Sulfate (SO)4 2-) When the content is considered as 0.3 wt%, high-purity K can be by-produced for each 1 ton of potassium hydroxide2SO4: 7.3kg/t KOH, while reducing the use of industrial barium chloride: 10.3t/t KOH;
the high-purity potassium sulfate as a byproduct has the following price in agricultural level: 2800 yuan/ton, industrial barium chloride 4000 yuan/ton according to market price; the yield of each ton of potassium hydroxide products can be increased by 61.7 yuan;
the production capacity of the ionic membrane potash in China at present is as follows: 130 million tons/year, the method has higher popularization value, and can gradually replace the barium method denitration or calcium method denitration process adopted in the existing potash plant at home and abroad at present.
Drawings
Fig. 1 is a schematic structural diagram of a system for denitration by a potassium sulfate product by a potassium chloride hydrothermal method according to an embodiment of the present invention.
Reference numerals: 1. nanofiltration membrane system, 2, salt water heater, 3, circulating pump, 4, circulating heater, 5, evaporator, 6, thickener, 7, centrifuge, 8, air flow dryer, 9, cyclone separator, 10, MVR vapor recompression system, 11, bag-type dust remover, 12, fan, 13, air heater, 14, air fan, 15, mother liquor buffer tank, 16 and mother liquor pump.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
In the description of the embodiments of the present invention, it should be noted that the indication of the orientation or the positional relationship is based on the orientation or the positional relationship shown in the drawings, or the orientation or the positional relationship which is usually placed when the product of the present invention is used, or the orientation or the positional relationship which is usually understood by those skilled in the art, or the orientation or the positional relationship which is usually placed when the product of the present invention is used, and is only for the convenience of describing the present invention and simplifying the description, but does not indicate or imply that the indicated device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, cannot be understood as limiting the present invention. Furthermore, the terms "first" and "second" are used merely to distinguish one description from another, and are not to be construed as indicating or implying relative importance.
In the description of the embodiments of the present invention, it should be further noted that the terms "disposed" and "connected" are to be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected, unless explicitly stated or limited otherwise; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood in specific cases by those skilled in the art; the drawings in the embodiments are used for clearly and completely describing the technical scheme in the embodiments of the invention, and obviously, the described embodiments are a part of the embodiments of the invention, but not all of the embodiments. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Example 1
Aiming at the problems existing in the sulfate radical removing process of the potash plant at present: 1) chemical is required to be added, 2) extra impurities are introduced, 3) solid waste is required to be discharged, and the like, the invention provides a novel sulfate radical removing system and a novel sulfate radical removing method, namely: a sulfate radical removing process without introducing impurities and generating solid waste at the same time comprises the following specific steps:
on the one hand, this embodiment provides a system of potassium chloride salt hydrothermal method denitration byproduct potassium sulfate product, and this system includes: receive filter membrane concentration unit, heat transfer unit, evaporative crystallization unit, centrifugal separation unit, recovery unit and drying unit, receive filter membrane concentration unit and pass through heat transfer unit is connected to evaporative crystallization unit, centrifugal separation unit and recovery unit three connect gradually, and the recovery unit is connected on the centrifugal separation unit.
The nanofiltration membrane unit receives dechlorinated light salt brine from an external potash device and concentrates the dechlorinated light salt brine, concentrated liquid after concentration is conveyed to the heat exchange unit, secondary gas condensate generated by the evaporation crystallization unit is conveyed to the heat exchange unit, heat exchange is carried out between the concentrated liquid and the secondary gas condensate in the heat exchange unit, the concentrated liquid after heat exchange is input to the evaporation crystallization unit to be evaporated and concentrated to obtain potassium sulfate crystals, the potassium sulfate crystals are treated by the centrifugal separation unit and then enter the drying unit to be dried to obtain qualified potassium sulfate products, and meanwhile, the centrifugal mother liquor is directly returned to the potash device through the recovery unit to carry out a secondary brine refining process.
Specifically, in this embodiment, as shown in fig. 1, the nanofiltration membrane concentration unit includes a nanofiltration membrane system, the heat exchange unit includes a brine heater, and the evaporative crystallization unit includes a circulation pump, a circulation heater, an evaporator, and an MVR vapor recompression system.
The nanofiltration membrane system and the circulating heater are respectively connected to the input end of the brine heater, one output end of the brine heater is connected to the evaporator, the brine heater exchanges heat between concentrated liquid transmitted by the nanofiltration membrane system and secondary gas condensate from the circulating heater, the concentrated liquid after heat exchange is transmitted to the evaporator for evaporative crystallization, and the secondary gas condensate after heat exchange is output through the other output end of the brine heater for waste heat recovery treatment.
The circulating heater, the circulating pump and the evaporator are in circulating connection, and secondary air condensate is provided for the brine heater through the circulating heater; one end of the MVR vapor recompression system is connected to the evaporator, the other end of the MVR vapor recompression system is connected to the circulating heater, and the MVR vapor recompression system controls the evaporation temperature to be 80-105 ℃ so as to save investment and reduce energy consumption.
Specifically, in this embodiment, as shown in fig. 1, the centrifugal separation unit includes a thickener and a centrifuge connected together, and the recovery unit includes a mother liquor buffer tank and a mother liquor pump connected together.
The thickener is connected to the evaporator, the mother liquor buffer tank is connected to the thickener, the potassium sulfate crystal separated out from the evaporator is thickened by the thickener, the thickened potassium sulfate crystal is input to the centrifugal machine for centrifugal separation, the centrifugal mother liquor is input to the mother liquor buffer tank, and the centrifugal mother liquor is conveyed to the potash device through the mother liquor pump for secondary brine refining.
Specifically, in this embodiment, as shown in fig. 1, the drying unit includes an airflow dryer, a cyclone separator, a bag-type dust remover, a fan, an air heater, and an air fan, where the airflow dryer, the cyclone separator, the bag-type dust remover, and the fan are sequentially connected, the airflow dryer is connected to the centrifugal separator, receives the potassium sulfate solid transmitted from the centrifugal separator, performs airflow drying on the potassium sulfate solid after centrifugal separation, and collects the potassium sulfate product obtained after drying from the cyclone separator and the bag-type dust remover to the packaging system; the air fan is connected with the air heater, the air heater is connected to the airflow dryer, and the air fan is matched with the air heater to input hot air to the airflow dryer so as to dry the potassium sulfate solid.
Wherein, the dryer can adopt a pulse dryer, and can also adopt fluidized bed dryers such as a boiling bed, a vibration fluidized bed and the like.
On the other hand, this embodiment also provides a method for denitration by a potassium sulfate product by a potassium chloride hydrothermal method, where in this embodiment, the method is implemented by the system shown in fig. 1, and mainly includes the following steps:
dechlorinated light salt brine from a potash plant, wherein the concentration of potassium sulfate is about 7g/l, and the dechlorinated light salt brine is input into a nanofiltration membrane system after the temperature of the dechlorinated light salt brine is adjusted so as to avoid the precipitation of potassium sulfate during the filtration of the nanofiltration membrane; by utilizing the interception effect of the nanofiltration membrane on divalent anions, the permeate (namely, nitrate-poor brine) is directly returned to the potash device for salt dissolving, and the potassium sulfate concentration of the concentrated solution (namely, nitrate-rich brine) is increased to 30-40 g/l.
The concentrated solution and secondary gas condensate from the circulating heater are subjected to heat exchange in a brine heat exchanger and then enter an evaporator, and the secondary gas condensate after heat exchange is output through a brine heater to perform waste heat recovery.
And (3) evaporating and concentrating the concentrated solution containing potassium sulfate by an evaporator to separate potassium sulfate crystals, allowing the potassium sulfate crystals to enter a thickener for thickening, cooling in the thickener, further growing the potassium sulfate crystals, and allowing the potassium sulfate crystals to enter a centrifuge for centrifugal separation.
After centrifugal separation, centrifugal mother liquor (namely nitrate-poor brine) with the potassium chloride concentration of 290-330 g/l is obtained, and after the centrifugal mother liquor is buffered in a mother liquor buffer tank, the centrifugal mother liquor is conveyed to a secondary brine refining process of a potash device through a mother liquor pump; and (4) drying the potassium sulfate solid obtained by centrifugal separation in an airflow dryer to obtain a qualified potassium sulfate product, and selling the potassium sulfate product as a compound fertilizer.
In the method, the purity of the potassium sulfate product can be adjusted by controlling the crystallization point and the washing water amount of the centrifugal machine, and the product requirements of different purities can be met.
The invention is not limited to the foregoing embodiments. The invention extends to any novel feature or any novel combination of features disclosed in this specification and any novel method or process steps or any novel combination of features disclosed. Those skilled in the art to which the invention pertains will appreciate that insubstantial changes or modifications can be made without departing from the spirit of the invention as defined by the appended claims.
Claims (10)
1. The utility model provides a system of potassium chloride salt hydrothermal method denitration by-product potassium sulfate product which characterized in that includes: the device comprises a nanofiltration membrane concentration unit, a heat exchange unit, an evaporative crystallization unit, a centrifugal separation unit and a drying unit, wherein the nanofiltration membrane concentration unit is connected to the evaporative crystallization unit through the heat exchange unit, and the evaporative crystallization unit, the centrifugal separation unit and the drying unit are sequentially connected;
the evaporative crystallization unit comprises a circulating pump, a circulating heater, an evaporator and an MVR vapor recompression system, wherein the circulating heater, the circulating pump and the evaporator are in circulating connection, one end of the MVR vapor recompression system is connected to the evaporator, and the other end of the MVR vapor recompression system is connected to the circulating heater;
the heat exchange unit comprises a brine heater, the input end of the brine heater is respectively connected with the nanofiltration membrane concentration unit and the circulating heater, the first output end of the brine heater is connected to the evaporator, and the second output end of the brine heater is used for recovering secondary gas condensate after heat exchange.
2. The system of claim 1, wherein the centrifugal separation unit comprises a thickener connected to the evaporator and a centrifuge connected to the drying unit, and the thickener and the centrifuge are connected to each other.
3. The system of claim 2, further comprising a recovery unit, wherein the recovery unit is connected to the centrifugal separation unit.
4. The system of claim 3, wherein the recovery unit comprises a mother liquor buffer tank and a mother liquor pump, the mother liquor buffer tank is connected to the thickener, and the mother liquor pump conveys the centrifugal mother liquor in the mother liquor buffer tank to a potash device for a secondary brine refining process.
5. The system of claim 1, wherein the drying unit comprises an air flow dryer, a cyclone separator, a bag-type dust collector and a fan, the air flow dryer is connected to the centrifugal separation unit, and the air flow dryer, the cyclone separator, the bag-type dust collector and the fan are connected in sequence.
6. The system of claim 5, wherein the drying unit further comprises an air heater and an air blower, the air heater is connected to the airflow dryer, and the air blower is connected to the air heater.
7. The system of claim 1, wherein the nanofiltration membrane concentration unit comprises a nanofiltration membrane system, and the nanofiltration membrane system is connected to the brine heater.
8. A method for denitration by a potassium sulfate product by a potassium chloride hydrothermal method is characterized by comprising the following steps:
the temperature of dechlorinated light salt brine from a potash device is regulated, the dechlorinated light salt brine is input to a nanofiltration membrane concentration unit to be concentrated with sulfate radicals, permeate liquid generated after concentration returns to the potash device for salt dissolving, and concentrate liquid generated after concentration is input to a heat exchange unit;
exchanging heat between the concentrated solution and the secondary gas condensate from the evaporative crystallization unit in a heat exchange unit, allowing the concentrated solution subjected to heat exchange to enter the evaporative crystallization unit, separating out potassium sulfate in the concentrated solution in the evaporative crystallization unit after evaporative concentration, and allowing the separated potassium sulfate crystals to enter a centrifugal separation unit for centrifugal separation;
and (4) drying the potassium sulfate solid obtained after centrifugal separation in a drying unit to obtain a potassium sulfate product.
9. The method of claim 8, further comprising: and centrifuging the potassium sulfate crystals to obtain centrifugal mother liquor, and returning the centrifugal mother liquor to a secondary brine refining process of the potash plant through a recovery unit.
10. The method of claim 8, further comprising: and (4) performing waste heat recovery on the secondary gas condensate after heat exchange through a heat exchange unit.
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| CN202110482847.8A CN113184882A (en) | 2021-04-30 | 2021-04-30 | System and method for denitration by-product potassium sulfate product by potassium chloride hydrothermal method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114620746A (en) * | 2022-04-18 | 2022-06-14 | 华融化学股份有限公司 | Method and system for removing sulfate radicals in potash light brine |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114620746A (en) * | 2022-04-18 | 2022-06-14 | 华融化学股份有限公司 | Method and system for removing sulfate radicals in potash light brine |
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