Seven-effect thermal-method nitre extraction device and process

Abstract

The invention relates to the technical field of salt production, in particular to a seven-effect hot-process saltpeter extraction device and process. The device comprises an I-effect evaporation tank, an II-effect evaporation tank, an III-effect evaporation tank, an IV-effect evaporation tank, a V-effect evaporation tank, a VI-effect evaporation tank and a VII-effect evaporation tank which are connected in sequence and have the same structure, the system further comprises a saltpeter tank, a salt collecting box, a flotation washing device, a salt slurry barrel, a salt settling device, a salty mud pump, a settler, an old brine buffer barrel, a saltpeter cyclone, a saltpeter centrifugal machine, a saltpeter drying bed, a salt thickener, conveying equipment, a salt drying bed, a low-temperature plate heat exchanger, a high-temperature plate heat exchanger and a mixing condenser. The first outlet of each effect evaporation tank is connected with the steam inlet of the next effect evaporation tank; a heating chamber, a circulating pump, an evaporation chamber and a balance barrel are arranged in the I-effect evaporation tank. The invention effectively solves the technical problem of low economic benefit of enterprises caused by high energy consumption and high equipment investment cost of the salt manufacturing process in the prior art.

Description

Technical Field

[0001] The invention relates to the technical field of salt production, and in particular to a seven-effect thermal method for extracting nitrate and a process thereof. Background Art

[0002] The domestic well salt brine type is mostly mirabilite brine, and mirabilite brine is generally Na 2 SO 4 The content is high, and it is very uneconomical to remove it by chemical methods, so it cannot be considered. At present, there are two main production processes for Glauber's salt-type brine commonly seen in China: one is the traditional vacuum salt production, also known as "vacuum evaporation salt production." When multiple evaporation tanks are connected in series to evaporate the feed liquid (brine), the secondary steam produced in the previous effect is used as the heat source required for the next evaporation process. Vacuum evaporation salt production often uses multi-effect evaporation to improve the utilization rate of thermal energy. Currently, four-effect and five-effect evaporation processes account for the vast majority. This method does not extract saltpeter, and avoids the enrichment of saltpeter by discharging a large amount of old brine. Therefore, the thermal utilization rate is not high, the quality of salt is not high, and the waste of saltpeter resources is serious. The second is the salt and saltpeter co-production process (also known as the mother liquor recovery method) introduced from abroad in the 1990s. This process has high resource utilization, good product quality, and a high degree of automation, but it has a lot of Na 2 SO 4 When the content is high, the output ratio of the salt system with higher thermal utilization rate decreases, and the output ratio of the salt-nitrate separation system with higher energy consumption increases, resulting in the overall energy consumption of the whole device increasing with the Na 2 SO 4 The content of nitrate increases rapidly, and the process requires brine purification, which further increases the cost. In the market environment where high quality does not mean high price, the competitiveness is low. Therefore, it is necessary to explore the energy-saving process of high-nitrate brine.

[0003] Thermal nitrate extraction is a nitrate extraction process developed in China in the early 1980s. 2 SO 4 In the reverse dissolution characteristic above 17.9℃ (the higher the temperature, the lower the solubility), the high-nitrate brine discharged from salt production is heated to about 100℃, and powdered salt is added to the preheated brine or it is evaporated and concentrated in a nitrate evaporator (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. + The common ion effect of Na 2 SO 4 The saltpeter is separated and the mother liquor is sent back to the salt making system to produce salt.

[0004] The characteristics of this method are: high thermal efficiency, full recovery of secondary steam, extraction of secondary steam for preheating, improved steam utilization, high salt concentration, small heat loss; short process flow for producing anhydrous sodium sulfate, no brine purification, low investment, closed brine circulation, no discharge of mother liquor, which can reduce the brine consumption of salt production and reduce environmental pollution. The disadvantages are: the quality of salt is not high, the quality of saltpeter is poor, because the calcium and magnesium impurities in the brine are not removed, some calcium and magnesium impurities enter the saltpeter tank, because the calcium and magnesium impurities enter the sodium sulfate, it is difficult to remove them by washing, and it is difficult to improve the quality of saltpeter, so that the quality of saltpeter can only reach about 95% or even lower, and the commercial value is slightly lower. Therefore, this process has not been promoted, and only Lantian Salt Chemical has persisted for many years, but the benefits are not good. The thermal salt extraction process has low investment, high thermal utilization rate, and it is urgent to solve the chronic problem of low product quality.

[0005] In recent years, with the sharp drop in the price of Glauber's salt and the sharp rise in fuel prices, the disadvantages of the once popular salt-salt co-production process with high consumption have gradually emerged, especially in the production of high-salt brine, where steam consumption remains high. Therefore, it is necessary to explore energy-saving processes for medium and high-salt brine. Summary of the invention

[0006] The present invention provides a seven-effect thermal method for extracting nitrate, and a process thereof, so as to solve the technical problems of high energy consumption and high equipment investment cost in the salt making process in the prior art, which leads to low economic benefits for the enterprise.

[0007] In order to solve the above problems, the seven-effect thermal nitrate extraction device provided by the present invention adopts the following technical solutions:

[0008] A seven-effect thermal method nitrate extraction device, comprising:

[0009] An evaporation tank group, comprising an effect I evaporation tank, an effect II evaporation tank, an effect III evaporation tank, an effect IV evaporation tank, an effect V evaporation tank, an effect VI evaporation tank and an effect VII evaporation tank, which are connected in sequence and have the same structure, and a steam inlet of the effect I evaporation tank is connected to an outlet of a raw steam source;

[0010] The I-effect evaporation tank is provided with a heating chamber, a circulating pump, an evaporation chamber and a balance barrel. The lower part of the I-effect evaporation tank is provided with the steam inlet, the top is provided with a first outlet for discharging secondary steam, the bottom is provided with a second outlet and a third outlet, and the second outlet is connected to the inlet of the salt collecting box;

[0011] The first outlet of each effect evaporator in the evaporator group is respectively connected to the steam inlet of the next effect evaporator, the first outlet of the seventh effect evaporator is connected to the inlet of the mixing condenser, and the outlet of the mixing condenser is connected to the circulating water pool;

[0012] The condensed water of each effect evaporator in the evaporator group enters the balance barrel of the effect through the third outlet and then transfers to the flash barrel or the balance barrel of the next effect evaporator. The third outlet of the V effect evaporator is connected to the high temperature plate heat exchanger, the third outlet of the VII effect evaporator is connected to the low temperature plate heat exchanger, the raw material inlet of the V effect evaporator, the VI effect evaporator and the VII effect evaporator is connected to the material outlet of the low temperature plate heat exchanger, the material inlet of the high temperature plate heat exchanger is connected to the outlet of the old brine pump, the material outlet of the high temperature plate heat exchanger is connected to the first material inlet of the nitrate tank, and the material inlet of the low temperature plate heat exchanger is connected to the outlet of the original brine pump;

[0013] The nitrate tank is provided with a nitrate heating chamber inside, the nitrate heating chamber is connected to the first outlet of the III-effect evaporation tank, and the raw material inlets of the I-effect evaporation tank, the II-effect evaporation tank, the III-effect evaporation tank and the IV-effect evaporation tank are connected to the first material outlet of the nitrate tank;

[0014] The outlet of the salt collecting box is connected to the inlet of the flotation washer; the bottom outlet of the flotation washer is connected to the inlet of the salt slurry barrel, and the top outlet is connected to the inlet of the salt settling device; the bottom outlet of the salt settling device is connected to the inlet of the salt mud pump, and the upper outlet is connected to the inlet of the settler, and the upper outlet of the settler is connected to the inlet of the old brine buffer barrel;

[0015] The outlet of the old brine buffer barrel is connected to the material inlet of the old brine pump, the outlet of the salt mud pump is connected to the second material inlet of the nitre tank, the second material outlet of the nitre tank is connected to the material inlet of the nitre cyclone, the material outlet of the nitre cyclone is connected to the inlet of the nitre centrifuge, the material outlet of the nitre centrifuge is connected to the inlet of the nitre drying bed, the outlet of the salt slurry barrel is connected to the material inlet of the salt thickener, the material outlet of the salt thickener is connected to the inlet of the salt centrifuge, and the outlet of the salt centrifuge is transported to the salt drying bed through a conveying equipment.

[0016] The beneficial effects of the seven-effect thermal nitrate extraction device provided by the present invention are:

[0017] 1. By adding an evaporator to the existing multi-effect vacuum evaporation salt production, that is, setting an evaporator group including seven evaporators connected in sequence, the secondary steam generated by each evaporator is used as the heat source of the next evaporator. This way of cascade utilization of heat energy greatly improves the utilization efficiency of energy without replacing or adding too much equipment, reduces energy waste, and reduces equipment investment costs. In addition, the feed liquid can be evaporated and concentrated in multiple evaporators in sequence by continuous evaporation, thereby greatly improving production efficiency. At the same time, the heat energy transfer between the evaporators of each effect makes the heat energy distribution of the whole system more uniform, which is conducive to maintaining a stable evaporation rate and product quality.

[0018] 2. The salt mud at the bottom of the salt settling device is sent to the saltpeter tank as the raw material for salt precipitation, which not only precipitates saltpeter, but also increases the NaCl content of the refined brine, realizing the maximum utilization of resources and being able to co-produce high-quality salt and NaCl. 2 SO 4 .

[0019] Through the above arrangement, the present invention effectively solves the technical problems in the prior art of high energy consumption and high equipment investment cost of the salt production process, which leads to low economic benefits for the enterprise.

[0020] Furthermore, a steam jet heat pump is provided between the I-effect evaporation tank and the raw steam source.

[0021] Furthermore, the outlet of the raw steam source is connected to a drying bed.

[0022] Furthermore, the outlet of the salt collecting box is connected to the inlet of the flotation washer via a salt slurry pump.

[0023] Furthermore, the material outlet of the nitrate tank is connected to the material inlet of the nitrate cyclone through a nitrate slurry pump.

[0024] Furthermore, the outlet of the salt slurry barrel is connected to the material inlet of the salt thickener through a salt slurry pump.

[0025] In order to solve the above problems, the seven-effect thermal nitrate extraction process provided by the present invention adopts the following technical solutions:

[0026] A seven-effect thermal nitrate extraction process, comprising:

[0027] After the raw steam enters the I-effect evaporator, it enters the heating chamber of the I-effect evaporator together with part of the secondary steam generated by the I-effect evaporator. The liquid in the I-effect evaporator uses the power of the circulating pump to exchange heat with the steam indirectly in the heating chamber, and then enters the evaporation chamber to boil and flash. The flashed steam enters the heating chamber of the II-effect evaporator. The flash steam of each effect evaporation chamber is used as the heat source of the next effect heating chamber in turn. The secondary steam generated by the VII-effect evaporator enters the mixing condenser, and the cooling water sent from the cooling pump room absorbs heat and is condensed into water, and then discharged into the circulating water pool with the cooling water;

[0028] The secondary steam from the III-effect evaporator is divided into two paths, one goes to the heating chamber of the IV-effect evaporator, and the other goes to the nitrate heating chamber;

[0029] The condensed water produced by each effect evaporator is sent back to the balance barrel of each effect evaporator through the condensed water coil, and part of the raw steam is sent to the drying bed for drying to obtain dry condensed water. The dry condensed water goes to the balance barrel of the I effect evaporator for flashing. The condensed water of each effect evaporator is transferred to the flash barrel or the balance barrel of the next effect evaporator for flashing. The condensed water of the V effect evaporator is pumped to the high temperature plate heat exchanger to preheat the old brine. The condensed water of the VII effect evaporator is pumped to the low temperature plate heat exchanger for heat exchange with the original brine and then discharged to the condensed water pool.

[0030] The raw brine in the raw brine storage tank is preheated by the low-temperature plate heat exchanger and then enters the V-effect evaporator to the VII-effect evaporator in turn. The old brine is preheated by the high-temperature plate heat exchanger and then enters the nitrate tank. After the nitrate is separated by the secondary steam of the III-effect, the refined brine is transported to the I-effect evaporator to the IV-effect evaporator. The salt slurry produced by each effect evaporator is discharged to the salt collecting box, washed by the flotation washer, and then sent to the salt thickener for centrifugal dehydration and drying.

[0031] The old brine obtained after washing salt in the flotation washer is sent to the salt settling device for precipitation. The supernatant obtained by precipitation is preheated and then enters the nitrate tank for salt precipitation. The salt mud at the bottom of the salt settling device is sent to the nitrate tank for salt precipitation. The nitrate slurry in the nitrate tank is discharged and then centrifuged for dehydration and drying to obtain finished nitrate. The clear liquid in the nitrate tank is transported to the I-effect evaporation tank and then to the IV-effect evaporation tank for feeding.

[0032] The beneficial effects of the seven-effect thermal nitrate extraction process provided by the present invention are:

[0033] 1. By adding an evaporator to the existing multi-effect vacuum evaporation salt production, that is, setting an evaporator group including seven evaporators connected in sequence, the secondary steam generated by each evaporator is used as the heat source of the next evaporator. This way of cascade utilization of heat energy greatly improves the utilization efficiency of energy without replacing or adding too much equipment, reduces energy waste, and reduces equipment investment costs. In addition, the feed liquid can be evaporated and concentrated in multiple evaporators in sequence by continuous evaporation, thereby greatly improving production efficiency. At the same time, the heat energy transfer between the evaporators of each effect makes the heat energy distribution of the whole system more uniform, which is conducive to maintaining a stable evaporation rate and product quality.

[0034] 2. The salt mud at the bottom of the salt settling device is sent to the saltpeter tank as the raw material for salt precipitation, which not only precipitates saltpeter, but also increases the NaCl content of the refined brine, realizing the maximum utilization of resources and being able to co-produce high-quality salt and NaCl. 2 SO 4 .

[0035] Through the above arrangement, the present invention effectively solves the technical problems in the prior art of high energy consumption and high equipment investment cost of the salt production process, which leads to low economic benefits for the enterprise.

[0036] Furthermore, a steam jet heat pump is arranged between the I-effect evaporator and the raw steam source. After the steam jet heat pump extracts part of the secondary steam generated by the I-effect evaporator, it reduces the temperature and pressure of the steam delivered from the raw steam source and delivers the treated steam to the I-effect heating chamber.

[0037] Furthermore, the outlet of the raw steam source is connected to a drying bed.

[0038] Furthermore, the material outlet of the nitrate tank is connected to the material inlet of the nitrate cyclone through a nitrate slurry pump, and the nitre slurry in the nitrate tank is discharged through the nitre slurry pump for dehydration and drying treatment; the first material outlet of the nitrate tank is connected to the raw material inlets of the I-effect evaporation tank, the II-effect evaporation tank, the III-effect evaporation tank and the IV-effect evaporation tank through a refined brine pump, and the clear liquid in the nitrate tank is transported to the I-effect evaporation tank, the II-effect evaporation tank, the III-effect evaporation tank and the IV-effect evaporation tank by the refined brine pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] By reading the following detailed description with reference to the accompanying drawings, the above and other objects, features and advantages of the exemplary embodiments of the present invention will become readily understood. In the accompanying drawings, several embodiments of the present invention are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein:

[0040] Figure 1 It is a structural schematic diagram of the seven-effect thermal nitrate extraction device provided by the present invention;

[0041] Figure 2 The present invention provides a seven-effect thermal nitrate extraction process flow chart.

[0042] Description of reference numerals:

[0043] 1. I-effect evaporation tank; 2. II-effect evaporation tank; 3. III-effect evaporation tank; 4. IV-effect evaporation tank; 5. V-effect evaporation tank; 6. VI-effect evaporation tank; 7. VII-effect evaporation tank; 8. Mixing condenser; 9. High-temperature plate heat exchanger; 10. Low-temperature plate heat exchanger; 11. Nitrate tank; 12. Salt collecting box; 13. Float washer; 14. Salt slurry barrel; 15. Salt settling device; 16. Salt mud pump; 17. Settling device; 18. Old brine buffer barrel; 19. Nitrate cyclone; 20. Nitrate centrifuge; 21. Nitrate drying bed; 22. Salt thickener; 23. Salt drying bed; 24. Wet salt belt conveyor; 25. Steam jet heat pump; 26. Salt slurry pump; 27. Old brine pump; 28. Nitrate slurry pump; 29. ​​Salt centrifuge. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Those skilled in the art should know that the embodiments described below are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0045] After introducing the basic principle of the present invention, various non-limiting embodiments of the present invention are described in detail below. The number of any element in the drawings is for illustration and not for limitation, and any naming is only for distinction and does not have any limiting meaning.

[0046] The principle and spirit of the present invention are explained in detail below with reference to several representative embodiments of the present invention.

[0047] Embodiments of the seven-effect thermal nitrate extraction device provided by the present invention:

[0048] like Figure 1 As shown, the seven-effect thermal saltpeter extraction device includes an evaporation tank group, a saltpeter tank 11, a salt collecting box 12, a flotation washer 13, a salt slurry barrel 14, a salt settling device 15, a salt mud pump 16, a settler 17, an old brine buffer barrel 18, a saltpeter cyclone 19, a saltpeter centrifuge 20, a saltpeter drying bed 21, a salt thickener 22, a conveying device, a salt drying bed 23, a low-temperature plate heat exchanger 10, a high-temperature plate heat exchanger 9 and a mixing condenser 8.

[0049] Regarding the evaporation tank group. The evaporation tank group includes a first effect evaporation tank 1, a second effect evaporation tank 2, a third effect evaporation tank 3, a fourth effect evaporation tank 4, a fifth effect evaporation tank 5, a sixth effect evaporation tank 6 and a seventh effect evaporation tank 7 which are connected in sequence and have the same structure. The steam inlet of the first effect evaporation tank 1 is connected to the outlet of the raw steam source. The I-effect evaporator 1 is provided with a heating chamber, a circulating pump, an evaporation chamber and a balance barrel. A steam inlet is provided at the lower part of the I-effect evaporator 1, a first outlet for discharging secondary steam is provided at the top thereof, and a second outlet and a third outlet are provided at the bottom thereof, wherein the second outlet is connected to the inlet of the salt collecting box 12; the first outlet of each effect evaporator in the evaporator group is respectively connected to the steam inlet of the next effect evaporator, the first outlet of the VII-effect evaporator 7 is connected to the inlet of the mixing condenser 8, and the outlet of the mixing condenser 8 is connected to the circulating water pool; the condensed water of each effect evaporator in the evaporator group enters the balance barrel of the next effect evaporator through the third outlet, the third outlet of the V-effect evaporator 5 is connected to the high-temperature plate heat exchanger 9, the third outlet of the VII-effect evaporator 7 is connected to the low-temperature plate heat exchanger 10 through a pipeline, the low-temperature plate heat exchanger 10 is connected to the raw brine storage tank, and the raw material inlets of the V-effect evaporator 5, the VI-effect evaporator 6 and the VII-effect evaporator 7 are connected to the material outlet of the low-temperature plate heat exchanger 10 through a pipeline.

[0050] About the nitrate tank 11. A nitrate heating chamber is arranged inside the nitrate tank 11, and the nitrate heating chamber is connected to the first outlet of the III-effect evaporation tank 3. The raw material inlets of the I-effect evaporation tank 1, the II-effect evaporation tank 2, the III-effect evaporation tank 3 and the IV-effect evaporation tank 4 are connected to the material outlet of the nitrate tank 11 through a pump and a pipeline.

[0051] The outlet of the salt collecting box 12 is connected to the inlet of the flotation washer 13 through a salt slurry pump 26 and a pipeline; the bottom outlet of the flotation washer 13 is connected to the inlet of the salt slurry barrel 14, and its top outlet is connected to the inlet of the salt settling device 15 through a pipeline; the bottom outlet of the salt settling device 15 is connected to the inlet of the salt mud pump 16, and its upper outlet is connected to the inlet of the settler 17, and the upper outlet of the settler 17 is connected to the inlet of the old brine buffer barrel 18; the outlet of the old brine buffer barrel 18 is connected to the material inlet of the nitrate tank 11 through the old brine pump 27 and a pipeline, and the outlet of the salt mud pump 16 is connected to the inlet of the salt settling device 15. The material outlet of the nitrate tank 11 is connected to the material inlet of the nitrate cyclone 19 through a nitrate slurry pump 28 and a pipeline, the material outlet of the nitrate cyclone 19 is connected to the inlet of the nitrate centrifuge 20, the material outlet of the nitrate centrifuge 20 is connected to the inlet of the nitrate drying bed 21, the outlet of the salt slurry barrel 14 is connected to the material inlet of the salt thickener 22 through a salt slurry pump 26 and a pipeline, the material outlet of the salt thickener 22 is connected to the inlet of the salt centrifuge, and the outlet of the salt centrifuge is transported to the salt drying bed 23 through a conveying equipment.

[0052] Among them, the conveying equipment is a wet salt belt conveyor 24.

[0053] In addition, a steam jet heat pump 25 is provided between the first effect evaporation tank 1 and the raw steam source, and the outlet of the raw steam source is connected to a drying bed.

[0054] It should be noted that the raw brine sent from the mining area is called original brine, which becomes old brine after washing salt, and becomes refined brine after saltpeter separation in the saltpeter tank 11.

[0055] The working principle of the seven-effect thermal nitrate extraction device provided by the present invention is:

[0056] First, the raw steam enters the steam jet heat pump 25 (if the raw steam pressure is not high, the heat pump is not set), and after mixing with the secondary steam generated by part of the I-effect evaporator 1 extracted by the steam jet heat pump 25, they enter the heating chamber in the I-effect evaporator 1 together. The liquid in the I-effect evaporator 1 uses the power of the circulating pump to indirectly exchange heat with the steam in the heating chamber in the heating chamber, and then enters the evaporation chamber to boil and flash. The flashed steam enters the heating chamber of the II-effect evaporator 2 as the heat source of the II-effect evaporator 2. The flash steam of each effect evaporation chamber is used as the heat source of the next effect heating chamber in turn; among them, the secondary steam of the III-effect evaporator 3 is divided into two paths, one goes to the heating chamber of the IV-effect evaporator 4, and the other goes to the nitrate heating chamber. The secondary steam generated by the VII-effect evaporator 7 enters the mixing condenser 8, and the cooling water sent from the cooling pump room absorbs heat and is condensed into water, and then discharged into the circulating water pool with the cooling water;

[0057] The condensed water produced by each effect evaporator is respectively sent back to the balance barrel of each effect evaporator by the condensed water coil, and part of the raw steam is sent to the drying bed for drying to obtain dry condensed water, which is then sent to the balance barrel of the I effect evaporator 1 for flashing, and the condensed water of each effect evaporator is respectively sent to the flashing barrel or the balance barrel of the next effect evaporator for flashing, and the condensed water of the V effect evaporator 5 is pumped to the high temperature plate heat exchanger 9 to preheat the old brine, and the condensed water of the VII effect evaporator 7 is pumped to the low temperature plate heat exchanger 10 for heat exchange with the original brine and then discharged to the condensed water pool;

[0058] A portion of the raw steam enters the drying bed for drying. The raw brine in the raw brine storage tank is preheated by the low-temperature plate heat exchanger and then enters the subsequent evaporation tanks in turn. The old brine is preheated by the high-temperature plate heat exchanger and then enters the nitrate tank 11. After the secondary steam of the III effect is heated to separate the nitrate, the refined brine is transported to the first several effect evaporation tanks. The salt slurry produced by each effect evaporation tank is discharged to the salt collecting box 12, washed by the flotation washer 13, and then sent to the salt thickener 22 for centrifugal dehydration and drying. The old brine obtained after washing the salt by the flotation washer 13 is sent to the salt settling device 15 for precipitation. The supernatant obtained by the precipitation is preheated and then enters the nitrate tank 11 for nitrate separation. The salt and nitrate mud at the bottom of the salt settling device 15 are sent to the nitrate tank 11. The nitrate slurry is centrifugally dehydrated and dried to obtain the finished nitrate. The clear liquid (refined brine) in the nitrate tank 11 enters the first several effect evaporation tanks.

[0059] Embodiment of the seven-effect thermal nitrate extraction process provided by the present invention:

[0060] like Figure 2 As shown, the seven-effect thermal nitrate extraction process includes the following steps:

[0061] After the raw steam enters the I-effect evaporator, it enters the heating chamber of the I-effect evaporator together with part of the secondary steam generated by the I-effect evaporator. The liquid in the I-effect evaporator uses the power of the circulating pump to exchange heat with the steam indirectly in the heating chamber, and then enters the evaporation chamber to boil and flash. The flashed steam enters the heating chamber of the II-effect evaporator. The flash steam of each effect evaporation chamber is used as the heat source of the next effect heating chamber in turn. The secondary steam generated by the VII-effect evaporator enters the mixing condenser, and the cooling water sent from the cooling pump room absorbs heat and is condensed into water, and then discharged into the circulating water pool with the cooling water;

[0062] The secondary steam from the III-effect evaporator is divided into two paths, one goes to the heating chamber of the IV-effect evaporator, and the other goes to the nitrate heating chamber;

[0063] The condensed water produced by each effect evaporator is sent back to the balance barrel of each effect evaporator through the condensed water coil, and part of the raw steam is sent to the drying bed for drying to obtain dry condensed water. The dry condensed water goes to the balance barrel of the I effect evaporator for flashing. The condensed water of each effect evaporator is transferred to the flash barrel or the balance barrel of the next effect evaporator for flashing. The condensed water of the V effect evaporator is pumped to the high temperature plate heat exchanger to preheat the old brine. The condensed water of the VII effect evaporator is pumped to the low temperature plate heat exchanger for heat exchange with the original brine and then discharged to the condensed water pool.

[0064] The raw brine in the raw brine storage tank is preheated by the low-temperature plate heat exchanger and then enters the V-effect evaporator to the VII-effect evaporator in turn. The old brine is preheated by the high-temperature plate heat exchanger and then enters the nitrate tank. After the nitrate is separated by the secondary steam of the III-effect, the refined brine is transported to the I-effect evaporator to the IV-effect evaporator. The salt slurry produced by each effect evaporator is discharged to the salt collecting box, washed by the flotation washer, and then sent to the salt thickener for centrifugal dehydration and drying.

[0065] The old brine obtained after washing salt in the flotation washer is sent to the salt settling device for precipitation. The supernatant obtained by precipitation is preheated and then enters the nitrate tank for salt precipitation. The salt mud at the bottom of the salt settling device is sent to the nitrate tank for salt precipitation. The nitrate slurry in the nitrate tank is discharged and then centrifuged for dehydration and drying to obtain finished nitrate. The clear liquid in the nitrate tank is transported to the I-effect evaporation tank and then to the IV-effect evaporation tank for feeding.

[0066] Among them, a steam jet heat pump is arranged between the I-effect evaporator and the raw steam source. After the steam jet heat pump extracts part of the secondary steam generated by the I-effect evaporator, the steam transported from the raw steam source is subjected to temperature and pressure reduction treatment, and the mixed steam enters the I-effect heating chamber; the outlet of the raw steam source is connected to a drying bed; the flotation scrubber is a three-stage flotation scrubber; the material outlet of the nitrate tank is connected to the material inlet of the nitrate cyclone through a nitrate slurry pump, and the nitrate slurry in the nitrate tank is discharged through the nitrate slurry pump for dehydration and drying treatment; the first material outlet of the nitrate tank is connected to the raw material inlets of the I-effect evaporator, the II-effect evaporator, the III-effect evaporator and the IV-effect evaporator through a refined brine pump, and the clear liquid in the nitrate tank is transported to the I-effect evaporator, the II-effect evaporator, the III-effect evaporator and the IV-effect evaporator by the refined brine pump.

[0067] It should be noted that if the pressure of the raw steam is not high, there is no need to install a steam jet heat pump between the I-effect evaporator and the raw steam source.

[0068] According to the above description of this specification, those skilled in the art may also understand that the terms used below, such as "up", "down", "front", "back", "left", "right", "width", "horizontal", "top", "bottom", "inside", "outside" and the like, which indicate orientation or positional relationships, are based on the orientation or positional relationships shown in the drawings of this specification, and are only for the purpose of facilitating the explanation of the scheme of the present invention and simplifying the description, rather than explicitly or implicitly indicating that the devices or elements involved must have the specific orientation, be constructed and operated in a specific orientation. Therefore, the above-mentioned orientation or positional relationship terms cannot be understood or interpreted as limitations on the scheme of the present invention.

[0069] In addition, in the description of this specification, “plurality” means at least two, for example, two, three or more, etc., unless otherwise clearly and specifically defined.

Claims

1. A seven-effect thermal nitrate extraction device, characterized in that: include: An evaporation tank group, comprising an effect I evaporation tank, an effect II evaporation tank, an effect III evaporation tank, an effect IV evaporation tank, an effect V evaporation tank, an effect VI evaporation tank and an effect VII evaporation tank, which are connected in sequence and have the same structure, and a steam inlet of the effect I evaporation tank is connected to an outlet of a raw steam source; The I-effect evaporation tank is provided with a heating chamber, a circulating pump, an evaporation chamber and a balancing tank. The lower part of the I-effect evaporation tank is provided with the steam inlet, the top is provided with a first outlet for discharging secondary steam, the bottom is provided with a second outlet and a third outlet, and the second outlet is connected to the inlet of the salt collecting box; the first outlet of each effect evaporation tank in the evaporation tank group is respectively connected to the steam inlet of the next effect evaporation tank, the first outlet of the VII-effect evaporation tank is connected to the inlet of the mixing condenser, and the outlet of the mixing condenser is connected to the circulating water pool; The condensed water of each effect evaporator in the evaporator group enters the balance barrel of the effect through the third outlet and then transfers to the flash barrel or the balance barrel of the next effect evaporator. The third outlet of the V effect evaporator is connected to the high temperature plate heat exchanger, the third outlet of the VII effect evaporator is connected to the low temperature plate heat exchanger, the raw material inlet of the V effect evaporator, the VI effect evaporator and the VII effect evaporator is connected to the material outlet of the low temperature plate heat exchanger, the material inlet of the high temperature plate heat exchanger is connected to the outlet of the old brine pump, the material outlet of the high temperature plate heat exchanger is connected to the first material inlet of the nitrate tank, and the material inlet of the low temperature plate heat exchanger is connected to the outlet of the original brine pump; The nitrate tank is provided with a nitrate heating chamber inside, the nitrate heating chamber is connected to the first outlet of the III-effect evaporation tank, and the raw material inlets of the I-effect evaporation tank, the II-effect evaporation tank, the III-effect evaporation tank and the IV-effect evaporation tank are connected to the first material outlet of the nitrate tank; The outlet of the salt collecting box is connected to the inlet of the flotation washer; the bottom outlet of the flotation washer is connected to the inlet of the salt slurry barrel, and the top outlet is connected to the inlet of the salt settling device; the bottom outlet of the salt settling device is connected to the inlet of the salt mud pump, and the upper outlet is connected to the inlet of the settler, and the upper outlet of the settler is connected to the inlet of the old brine buffer barrel; The outlet of the old brine buffer barrel is connected to the material inlet of the old brine pump, the outlet of the salt mud pump is connected to the second material inlet of the nitre tank, the second material outlet of the nitre tank is connected to the material inlet of the nitre cyclone, the material outlet of the nitre cyclone is connected to the inlet of the nitre centrifuge, the material outlet of the nitre centrifuge is connected to the inlet of the nitre drying bed, the outlet of the salt slurry barrel is connected to the material inlet of the salt thickener, the material outlet of the salt thickener is connected to the inlet of the salt centrifuge, and the outlet of the salt centrifuge is transported to the salt drying bed through a conveying equipment.

2. The seven-effect thermal nitrate extraction device according to claim 1, characterized in that: A steam jet heat pump is arranged between the I-effect evaporation tank and the raw steam source.

3. The seven-effect thermal nitrate extraction device according to claim 1, characterized in that: The outlet of the raw steam source is connected with a drying bed.

4. The seven-effect thermal nitrate extraction device according to claim 1, characterized in that: The outlet of the salt collecting box is connected to the inlet of the flotation washer through a salt slurry pump.

5. The seven-effect thermal nitrate extraction device according to claim 1, characterized in that: The material outlet of the nitrate tank is connected to the material inlet of the nitrate cyclone through a nitrate slurry pump.

6. The seven-effect thermal nitrate extraction device according to claim 1, characterized in that: The outlet of the salt slurry barrel is connected to the material inlet of the salt thickener through a salt slurry pump.

7. A seven-effect thermal nitrate extraction process, characterized in that: The method is implemented by using the seven-effect thermal nitrate extraction device according to any one of claims 1 to 6, and the specific steps are as follows: After the raw steam enters the I-effect evaporator, it enters the heating chamber of the I-effect evaporator together with part of the secondary steam generated by the I-effect evaporator. The liquid in the I-effect evaporator uses the power of the circulating pump to exchange heat with the steam indirectly in the heating chamber, and then enters the evaporation chamber to boil and flash. The flashed steam enters the heating chamber of the II-effect evaporator. The flash steam of each effect evaporation chamber is used as the heat source of the next effect heating chamber in turn. The secondary steam generated by the VII-effect evaporator enters the mixing condenser, and the cooling water sent from the cooling pump room absorbs heat and is condensed into water, and then discharged into the circulating water pool with the cooling water; The secondary steam from the III-effect evaporator is divided into two paths, one goes to the heating chamber of the IV-effect evaporator, and the other goes to the nitrate heating chamber; The condensed water produced by each effect evaporator is sent back to the balance barrel of each effect evaporator through the condensed water coil, and part of the raw steam is sent to the drying bed for drying to obtain dry condensed water. The dry condensed water goes to the balance barrel of the I effect evaporator for flashing. The condensed water of each effect evaporator is transferred to the flash barrel or the balance barrel of the next effect evaporator for flashing. The condensed water of the V effect evaporator is pumped to the high temperature plate heat exchanger to preheat the old brine. The condensed water of the VII effect evaporator is pumped to the low temperature plate heat exchanger for heat exchange with the original brine and then discharged to the condensed water pool. The raw brine in the raw brine storage tank is preheated by the low-temperature plate heat exchanger and then enters the V-effect evaporator to the VII-effect evaporator in turn. The old brine is preheated by the high-temperature plate heat exchanger and then enters the nitrate tank. After the nitrate is separated by the secondary steam of the III-effect, the refined brine is transported to the I-effect evaporator to the IV-effect evaporator. The salt slurry produced by each effect evaporator is discharged to the salt collecting box, washed by the flotation washer, and then sent to the salt thickener for centrifugal dehydration and drying. The old brine obtained after washing salt in the flotation washer is sent to the salt settling device for precipitation. The supernatant obtained by precipitation is preheated and then enters the nitrate tank for salt precipitation. The salt mud at the bottom of the salt settling device is sent to the nitrate tank for salt precipitation. The nitrate slurry in the nitrate tank is discharged and then centrifuged for dehydration and drying to obtain finished nitrate. The clear liquid in the nitrate tank is transported to the I-effect evaporation tank and then to the IV-effect evaporation tank for feeding.

8. The seven-effect thermal nitrate extraction process according to claim 7, characterized in that: A steam jet heat pump is arranged between the I-effect evaporation tank and the raw steam source. The steam jet heat pump extracts part of the secondary steam generated by the I-effect evaporation tank, then reduces the temperature and pressure of the steam delivered from the raw steam source, and delivers the treated steam to the I-effect heating chamber.

9. The seven-effect thermal nitrate extraction process according to claim 7, characterized in that: The outlet of the raw steam source is connected with a drying bed.

10. The seven-effect thermal nitrate extraction process according to claim 7, characterized in that: The material outlet of the nitrate tank is connected to the material inlet of the nitrate cyclone through a nitrate slurry pump, and the nitre slurry in the nitrate tank is discharged through the nitre slurry pump for dehydration and drying; the first material outlet of the nitrate tank is connected to the raw material inlets of the I-effect evaporation tank, the II-effect evaporation tank, the III-effect evaporation tank and the IV-effect evaporation tank through a refined brine pump, and the clear liquid in the nitrate tank is transported to the I-effect evaporation tank, the II-effect evaporation tank, the III-effect evaporation tank and the IV-effect evaporation tank by the refined brine pump.

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