CN115557518A - Method for salt-nitrate co-production through six-effect TVR evaporation glauberite double salt separation method - Google Patents
Method for salt-nitrate co-production through six-effect TVR evaporation glauberite double salt separation method Download PDFInfo
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- CN115557518A CN115557518A CN202211343312.3A CN202211343312A CN115557518A CN 115557518 A CN115557518 A CN 115557518A CN 202211343312 A CN202211343312 A CN 202211343312A CN 115557518 A CN115557518 A CN 115557518A
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- 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
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- C—CHEMISTRY; METALLURGY
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- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
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Abstract
The invention discloses a salt-nitrate co-production method by a six-effect TVR evaporative glauberite double salt separation method. Compared with the traditional salt and nitrate co-production process (Switzerland longevity-Esetervis production process), the method has the advantages of low steam consumption and good economical efficiency based on the six-effect TVR evaporator, and meanwhile, the method has strong adaptability to the original halogen and is simple to operate and control.
Description
Technical Field
The invention belongs to the field of salt-nitrate co-production, and particularly relates to a salt-nitrate co-production method by a six-effect TVR evaporation glauberite double salt separation method.
Background
The raw bittern types of the main salt production areas in China are sodium sulfate types, the average content of the sodium sulfate with the side content is more than 22g/L besides the main content of sodium chloride in the raw bittern, and in addition, the raw bittern also contains a small amount of impurities such as calcium sulfate, magnesium sulfate and the like. The salt-making production process of this type of original halogen generally adopts the salt-nitrate co-production process introduced from abroad, sulshou-Elithervis corporation, switzerland, in the actual production, salt and nitrate are respectively crystallized from a salt-nitrate system. For controlling the salt quality (nitrate does not crystallize out in the salt system), according to NaCl-Na 2 SO 4 -H 2 The ternary phase diagram of the O water salt system needs to discharge a large amount of mother liquor in the tank to ensure that mirabilite in the salt system is not saturated, so that the mirabilite can not be crystallized out in the salt system.
Because of the large amount of mother liquor discharged from the tank, the heat loss of the system is large, so that the steam consumption of the salt and nitrate co-production process is high, and the steam consumption per ton of product reaches more than 1.1, thus leading to high production cost and poor economic benefit.
In addition, because the original halogen is at normal temperature, in order to fully utilize the heat energy of condensed water, the original halogen is preheated by effect division and then is added into a tank. The existing process has the main problems that: the first problem is that: due to impurities (mainly Na) in the original halogen 2 SO 4 ) High content of Na in salt system 2 SO 4 Saturated and separated out to cause the situation that the salt quality does not reach the standard, so a large amount of mother liquor in the tank must be discharged to ensure Na 2 SO 4 Is unsaturated. The process has large mother liquor circulation and large heat loss (heat loss sources: pipeline loss and heat backward movement), so that the steam consumption of the system is high and uneconomical. The second problem is that: all the raw brine enters an evaporation system, and a fractional preheating mode is adopted for fully utilizing the heat of condensed water due to low temperature of the raw brine. During preheating, if the original halogen is not purified (containing Na) 2 SO 4 About 22g/L, caSO 4 About 1.65 g/L), and CaSO 4 The solubility is minimum at 70-90 ℃, caSO4 can be crystallized and separated out from the system due to CaSO 4 The solubility is low, and the scale can be quickly formed on the inner surfaces of pipelines and equipment, so that the heat transfer coefficient and efficiency of the system are plugged or reduced.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a salt-nitrate co-production method by a six-effect TVR evaporation glauberite double salt separation method.
The purpose of the invention is realized by the following technical scheme:
a method for salt-nitrate co-production by a six-effect TVR evaporation glauberite double salt separation method comprises the following steps:
(1) Low-pressure steam is used as driving steam, secondary steam generated by the first-effect evaporation tank is sucked, mixed steam enters a heating chamber of the first-effect evaporation tank and is used as a heat source to heat original halogen in the first-effect evaporation tank, and secondary steam generated after boiling enters a heating chamber of the second-effect evaporation tank and is used as a heat source to heat original halogen in the second-effect evaporation tank; the first-effect evaporation tank, the second-effect evaporation tank, the third-effect evaporation tank, the fourth-effect evaporation tank, the fifth-effect evaporation tank and the sixth-effect evaporation tank are sequentially connected in series until secondary steam generated by the sixth-effect evaporation tank enters an atmospheric condenser to form vacuum; discharging the salt slurry to a first-stage floatation device of a salt washing system, taking original brine as washing liquid, entering a third-stage floatation device, performing three-stage countercurrent washing, discharging the salt slurry from the third-stage floatation device, and performing centrifugal dehydration to obtain wet salt;
(2) Mixing the salt washing mother liquor generated by the first-stage floatation scrubber with mother liquor discharged by a nitrate system, preheating the mixture by three stages, raising the temperature to 95-100 ℃, separating out coarse nitrate, and leaching and separating the coarse nitrate to obtain CaSO 4 ·2H 2 O; the nitrate solution enters a fine nitrate evaporation crystallizer, and nitrate slurry generated by fine nitrate evaporation is dehydrated and dried to obtain the fine finished product nitrate.
Preferably, the wet salt in the step (1) is dried to obtain the finished product of dry salt.
Preferably, the first-stage preheating heat source in the three-stage preheating in the step (2) is condensed water.
Preferably, the second-stage preheating heat source in the third-stage preheating in the step (2) is condensed water.
Preferably, the heat source of the third stage preheating in the step (2) is secondary steam generated by a single-effect evaporation tank.
Preferably, the leaching in step (2) is leaching in water.
Preferably, the crude nitrate in the step (2) is CaSO 4 And Na 2 SO 4 The double salt of (1).
Preferably, the temperature of the secondary steam generated by the single-effect evaporation tank in the step (1) is 144 ℃.
Preferably, the original halogen in the step (1) is taken as a washing liquid and enters a three-stage flotation washer at the speed of 0.01-0.02 m/s.
Preferably, the heat source used for fine saltpeter evaporation in the step (2) is secondary steam generated by a single-effect evaporation tank.
Preferably, the condensed water generated by the refined saltpeter evaporative crystallizer in the step (2) is in equilibrium flash vaporization with the condensed water in the third-stage preheating and the second-stage preheating, and flash vapor enters a heating chamber of the four-effect evaporation tank.
Compared with the prior art, the invention has the beneficial effects that:
(1) Low steam consumption and good economical efficiency. The traditional salt and nitrate co-production process (adopting the introduced Swiss Sulsho-Eseivis production process) consumes 1.1t/t of steam, and has excellent heat utilization: the evaporating pot 201 is additionally provided with a heat pump for pumping secondary steam, the steam is used for one time more, the tail part is evaporated, sprayed and pumped with noncondensable gas, the final effect vacuum degree is high, and the total effective temperature difference is high. The steam consumption of the production process can reach 0.58t/t.
(2) The adaptability of the original halogen is strong, and the operation and control are simple. Conventional co-production of saltpeter, once Na is contained in original halogen 2 SO 4 The components are greatly changed, salt and nitrate in the tank are easily eutectoid, the quality of the original salt is reduced, and the production is interrupted when the quality is serious. The production process adopts salting-out method to extract saltpeter, the salt and the saltpeter are co-precipitated in an evaporation tank, the saltpeter is removed through a salt washing system, the salt quality is improved, and the requirement on the original bittern is not required, so Na in the original bittern 2 SO 4 The component fluctuation can not cause any influence on the production, so the operation and control are simple, and the production process is continuous and reliable.
Drawings
Fig. 1 is a schematic flow diagram of a salt-nitrate co-production method by a six-effect TVR evaporative glauber salt double salt separation method according to the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.
Referring to fig. 1, fig. 1 is a schematic flow diagram of a salt-nitrate co-production method by a six-effect TVR evaporative glauberite double salt separation method according to the present invention.
Example 1
The invention provides a salt-nitrate co-production method by a six-effect TVR evaporation glauberite double salt separation method by adopting a six-effect TVR evaporator, which comprises the following steps:
(1) Low-pressure steam is used as driving steam, secondary steam generated by the first-effect evaporation tank 201 is sucked, mixed steam enters a heating chamber of the first-effect evaporation tank 201 and is used as a heat source to heat primary halogen in the first-effect evaporation tank, and secondary steam generated after boiling enters a heating chamber of the second-effect evaporation tank 202 and is used as a heat source to heat primary halogen in the second-effect evaporation tank; the first-effect evaporation tank 201, the second-effect evaporation tank 202, the third-effect evaporation tank 203, the fourth-effect evaporation tank 204, the fifth-effect evaporation tank 205 and the sixth-effect evaporation tank 206 are sequentially connected in series until secondary steam generated by the sixth-effect evaporation tank 206 enters an atmospheric condenser to form vacuum; discharging the salt slurry to a first-stage flotation washer of a salt washing system, taking the original brine as a washing liquid at the flow rate of 0.012m/s, entering a third-stage flotation washer, performing third-stage countercurrent washing, discharging the salt slurry from the third-stage flotation washer, and performing centrifugal dehydration to obtain wet salt; drying the wet salt at 70-100 ℃ to obtain finished dry salt;
(2) Mixing the salt washing mother liquor generated by the first-stage floatation scrubber with the mother liquor discharged by a saltpeter system, preheating for three stages, raising the temperature to 95-100 ℃, and separating out crude saltpeter (CaSO) 4 ·Na 2 SO 4 Double salt) is added with water to be leached and separated, and then CaSO is obtained 4 ·2H 2 Comprehensively utilizing O slag or injecting well, feeding nitrate liquid into a refined nitrate evaporation crystallizer, taking secondary steam generated by a primary effect evaporation tank 201 system at the temperature of about 144 ℃ as a heating heat source, balancing flash evaporation of condensed water generated by the refined nitrate evaporation crystallizer with three-stage preheating water and two-stage pre-condensing water, and feeding flash evaporation steam into a four-effect evaporation tank heating chamber; and dewatering and drying the nitrate slurry generated by the evaporation of the refined nitrate to obtain the refined product nitrate.
Comparative example 1
A method for preparing salt from sodium sulfate type raw halogen comprises the following steps:
the procedure was as described in example 1 of patent CN 108314062A.
The technical and economic indicators of the process described in example 1 and comparative example 1 of the present invention are summarized as follows, and are shown in Table 1.
TABLE 1 statistical summary of economic indicators
1. Description of the drawings:
steam 160 yuan/ton product; the raw halogen purification cost is 25.8 yuan/ton (raw halogen purification process is lime-mirabilite-CO) 2 Method).
The invention is adopted: steam consumption was reduced from 0.75 ton/ton product to 0.58 ton/ton product.
The invention is adopted: the original halogen needs to be purified, and the purification cost is 25.8 yuan per ton of product.
The invention is adopted: the salt quality can be improved from 99.2% to more than 99.4%. The nitrate content can be increased to more than 98%.
2. Evaluation:
the invention is adopted: can improve the quality of salt and nitre products.
The invention is adopted: the cost can be reduced by 1.4 yuan/ton.
The above-described embodiments of the present invention should not be construed as limiting the scope of the present invention. Any other corresponding changes and modifications made according to the technical idea of the present invention should be included in the protection scope of the claims of the present invention.
Claims (10)
1. A method for salt-nitrate co-production by a six-effect TVR evaporation glauberite double salt separation method is characterized by comprising the following steps:
(1) Low-pressure steam is used as driving steam, secondary steam generated by the first-effect evaporation tank is pumped, the mixed steam enters a heating chamber of the first-effect evaporation tank and is used as a heat source to heat original halogen in the first-effect evaporation tank, and the secondary steam generated after boiling enters a heating chamber of the second-effect evaporation tank and is used as the heat source to heat the original halogen in the second-effect evaporation tank; the first-effect evaporation tank, the second-effect evaporation tank, the third-effect evaporation tank, the fourth-effect evaporation tank, the fifth-effect evaporation tank and the sixth-effect evaporation tank are sequentially connected in series until secondary steam generated by the sixth-effect evaporation tank enters an atmospheric condenser to form vacuum; discharging the salt slurry to a first-stage floatation device of a salt washing system, taking original brine as washing liquid, entering a third-stage floatation device, discharging the salt slurry from the third-stage floatation device after three-stage countercurrent washing, and obtaining wet salt after centrifugal dehydration;
(2) Mixing the salt washing mother liquor generated by the first-stage floatation scrubber with mother liquor discharged by a nitrate system, preheating the mixture by three stages, raising the temperature to 95-100 ℃, separating out coarse nitrate, and leaching and separating the coarse nitrate to obtain CaSO 4 ·2H 2 O; the nitrate solution enters a fine nitrate evaporation crystallizer, and fine nitrate evaporation is carried outThe generated nitre slurry is dehydrated and dried to obtain the finished nitre.
2. The method for co-production of saltpeter by six-effect TVR evaporation glauber salt double salt separation method according to claim 1, wherein the raw brine in step (1) is used as washing liquid and enters a three-stage flotation device at a speed of 0.01-0.02 m/s.
3. The method for co-producing salt and nitrate by double salt separation of six-effect TVR evaporation glauber salt according to claim 1 or 2, wherein the heat source used in the fine nitrate evaporation of the step (2) is secondary steam generated by a single-effect evaporation tank.
4. The method for co-production of salt and nitrate by six-effect TVR evaporation glauberite double salt separation method according to claim 3, wherein the heat source of the third stage preheating in the third stage preheating of step (2) is secondary steam generated by a single-effect evaporation tank.
5. The method for co-production of salt and nitrate by six-effect TVR evaporation glauberite double salt separation method according to claim 4, wherein the leaching in step (2) is leaching in water;
and (2) drying the wet salt in the step (1) to obtain the finished product of dry salt.
6. The method for co-producing salt and nitrate by using the six-effect TVR evaporative glauberite double salt separation method according to claim 1 or 2, wherein a first-stage preheating heat source in the three-stage preheating in the step (2) is condensed water.
7. The method for co-production of salt and nitrate by six-effect TVR evaporation glauberite double salt separation method according to claim 6, wherein the second-stage preheating heat source in the third-stage preheating of step (2) is condensed water.
8. The method for co-producing salt and nitrate by using six-effect TVR evaporation glauberite double salt separation method according to claim 7, wherein the crude nitrate in the step (2) is CaSO 4 And Na 2 SO 4 The double salt of (1).
9. The method for co-production of salt and nitrate by six-effect TVR evaporation glauberite double salt separation method according to claim 8, wherein the temperature of the secondary steam generated by the primary evaporation tank in step (1) is 144 ℃.
10. The method for co-production of salt and nitrate by using a six-effect TVR evaporation glauber salt double salt separation method according to claim 9, wherein the condensed water produced by the fine nitrate evaporation crystallizer in the step (2) is in equilibrium flash with the condensed water of the third-stage preheating and the second-stage preheating, and flash steam enters a heating chamber of a four-effect evaporation tank.
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108314062A (en) * | 2018-02-06 | 2018-07-24 | 孝感广盐华源制盐有限公司 | A kind of hot method of continuously saltouing puies forward the production technology of nitre |
| CN115010150A (en) * | 2022-04-28 | 2022-09-06 | 中盐长江盐化有限公司 | MVR hot method saltpeter extraction process |
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- 2022-10-31 CN CN202211343312.3A patent/CN115557518A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108314062A (en) * | 2018-02-06 | 2018-07-24 | 孝感广盐华源制盐有限公司 | A kind of hot method of continuously saltouing puies forward the production technology of nitre |
| CN115010150A (en) * | 2022-04-28 | 2022-09-06 | 中盐长江盐化有限公司 | MVR hot method saltpeter extraction process |
Non-Patent Citations (1)
| Title |
|---|
| 许晓慧主编: "盐化工生产技术", vol. 1, 中央广播电视大学出版社, pages: 73 - 79 * |
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