Flash evaporation acid liquor recycling system

Abstract

The utility model relates to the technical field of chemical equipment, and provides a flash evaporation acid liquor recycling system, a preheating unit comprises at least one preheating tower, the preheating tower can be communicated with a first feed port of a reaction kettle and is used for preheating ore pulp, a flash evaporation unit comprises at least one flash evaporation tank, the flash evaporation tank can be communicated with a first discharge port of the reaction kettle, and the flash evaporation tank is used for preheating ore pulp. A steam outlet of the flash tank can be communicated with the heat exchanger of the preheating tower through a steam pipe, and the gas-liquid separator is arranged on the steam pipe and used for separating sulfuric acid liquid drops in steam. Compared with the prior art, the flash evaporation acid liquor recycling system has the advantages that the gas-liquid separator is arranged on the steam pipeline of the flash evaporation tank, sulfuric acid in steam is separated and recycled, and only the pipeline in front of the gas-liquid separator needs to be subjected to anti-corrosion treatment, so that scaling of the preheating tower is avoided, and the cost of anti-corrosion treatment of the pipeline is reduced; and the waste of sulfuric acid is also reduced.

Description

Technical Field

[0001] This utility model relates to the field of chemical equipment technology, and in particular to a flash evaporation acid recovery system. Background Technology

[0002] Flash evaporation involves transferring a high-pressure slurry from a reactor into a lower-pressure container. The sudden pressure drop transforms the slurry into saturated steam and saturated slurry at the lower pressure of the container. Since the boiling point of a substance is proportional to its pressure, this process lowers the boiling point of the high-pressure, high-temperature slurry before it enters the flash evaporation tank. The purpose of the flash tank is to provide a space for rapid vaporization and gas-liquid separation of the fluid.

[0003] In the hydrometallurgical process for laterite nickel ore, ore slurry, sulfuric acid, and steam are typically injected into a reaction vessel for smelting to extract nickel and cobalt from the ore. After the reaction, the ore slurry and sulfuric acid are introduced into a flash tank under reduced pressure. As steam is generated, some sulfuric acid droplets are also agitated by the vibrations caused by the steam, forming acid mist that is discharged along with the steam.

[0004] Because steam contains sulfuric acid, when using this steam to preheat the slurry, the sulfuric acid will react with the slurry in the preheating tower to produce precipitation, resulting in scaling inside the preheating tower; in addition, it will also cause corrosion of the steam pipes and additional consumption of sulfuric acid.

[0005] Therefore, there is an urgent need for a flash acid recovery system to solve the above-mentioned technical problems. Utility Model Content

[0006] The purpose of this invention is to propose a flash acid recovery system to solve the technical problem that the steam generated by the flash tank contains sulfuric acid, which causes scaling inside the preheating tower, corrodes the steam delivery pipeline, and increases sulfuric acid consumption when preheating the slurry.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] The flash acid recovery system includes:

[0009] Reactor;

[0010] The preheating unit includes at least one preheating tower, which is connected to the first feed inlet of the reactor and is used to preheat the slurry.

[0011] The flash evaporation unit includes at least one flash tank, which is connected to the first outlet of the reactor. The flash tank is used to flash the slurry after the reaction, and the steam outlet of the flash tank is connected to the heat exchanger of the preheating tower via a steam pipe.

[0012] A gas-liquid separator is installed on the steam pipe to separate sulfuric acid droplets from the steam.

[0013] As a preferred technical solution of the above-mentioned flash acid recycling system, multiple flash tanks are provided and connected in series, and the pressure value of the flash tanks decreases step by step along the direction of the slurry transfer.

[0014] As a preferred technical solution of the above-mentioned flash acid recovery system, multiple preheating towers are provided and connected in series. The multiple preheating towers are connected to the multiple flash tanks respectively. The temperature of the preheating towers increases step by step along the transfer direction of the slurry.

[0015] As a preferred technical solution for the above-mentioned flash acid recovery system, multiple preheating towers and multiple flash tanks are connected in a one-to-one correspondence.

[0016] As a preferred technical solution of the aforementioned flash acid recovery system, the gas-liquid separator includes a shell and a liquid-separating baffle. The shell has a separation chamber and also forms an air inlet, an air outlet, and a liquid outlet that communicate with the separation chamber. The liquid-separating baffle is disposed on the airflow path between the air inlet and the air outlet, and the liquid outlet is located below the liquid-separating baffle. The air inlet is connected to the steam outlet of the flash tank, and the air outlet is connected to the heat exchanger interface of the preheating tower.

[0017] As a preferred technical solution of the above-mentioned flash acid recovery system, the bottom surface of the outer shell is a slope, and the liquid outlet is located at the lowest point of the slope.

[0018] As a preferred technical solution of the above-mentioned flash acid recycling system, the liquid separating baffle has multiple bending structures to divide multiple bending channels in the separation chamber. When the vapor passes through the channels, sulfuric acid droplets will hit the liquid separating baffle and drip down.

[0019] As a preferred technical solution of the above-mentioned flash acid recovery system, the gas-liquid separator further includes a storage tank, the upper end of which is connected to the liquid outlet, and the lower end of which has a closable drain port.

[0020] As a preferred technical solution of the above-mentioned flash acid reuse system, it also includes a collection tank, the above-mentioned discharge port is connected to the collection tank through a sulfuric acid pipe, and a valve is installed on the above-mentioned sulfuric acid pipe.

[0021] As a preferred technical solution of the above-mentioned flash acid recycling system, the steam pipe is in contact with the collection tank to heat the sulfuric acid in the collection tank.

[0022] The beneficial effects of this utility model are:

[0023] The slurry is first transported to a preheating tower and preheated to a certain temperature before being transported to a reactor for reaction. After reaction, the slurry enters a flash tank for cooling. The steam generated in the flash tank has a relatively high temperature and is introduced into the preheating tower through steam pipes to preheat the slurry, thus fully utilizing energy. A gas-liquid separator is installed on the steam pipes to separate sulfuric acid droplets from the steam. This prevents sulfuric acid from corroding the steam pipes and also allows for the full recovery of sulfuric acid from the steam. Furthermore, only the steam pipes between the gas-liquid separator and the flash tank need corrosion protection, which avoids scaling in the preheating tower, reduces the cost of pipeline corrosion protection, and minimizes sulfuric acid waste. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments of this utility model will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the content of the embodiments of this utility model and these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the structure of the flash acid recovery system provided in an embodiment of the present invention;

[0026] Figure 2 for Figure 1 Cross-sectional view of a gas-liquid separator.

[0027] In the picture:

[0028] 1. Preheating unit; 11. First preheating tower; 12. Second preheating tower; 13. Third preheating tower;

[0029] 2. Reactor;

[0030] 3. Flash evaporation unit; 31. First flash evaporator; 32. Second flash evaporator; 33. Third flash evaporator;

[0031] 401. Outer shell; 402. Liquid separating baffle; 403. Air inlet; 404. Air outlet; 405. Liquid outlet; 406. Liquid storage tank; 407. Liquid drain; 41. First gas-liquid separator; 42. Second gas-liquid separator; 43. Third gas-liquid separator;

[0032] 5. Steam pipe; 6. Collection tank. Detailed Implementation

[0033] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.

[0034] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0035] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0036] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0037] This application provides a flash acid recovery system. This flash acid recovery system can be applied in the smelting of laterite nickel ore to recover sulfuric acid from the steam generated in the flash tank, thereby preventing sulfuric acid from corroding pipelines.

[0038] It should be noted that the flash acid recovery system of this application is used, but not limited to, in the smelting of laterite nickel ore, and can also be applied to other smelting production processes that require sulfuric acid and flash tanks. In this application, only the application of the flash acid recovery system in the smelting of laterite nickel ore is used as an example for illustration. The principle of the flash acid recovery system applied to the smelting of other ores is essentially the same as that applied to the smelting of laterite nickel ore, and will not be elaborated here.

[0039] like Figure 1 As shown, this utility model provides a flash acid recovery system, including: a reaction vessel 2, a preheating unit 1, a flash evaporation unit 3, and a gas-liquid separator. The preheating unit 1 includes at least one preheating tower connected to the first inlet of the reaction vessel 2, used to preheat the slurry. The flash evaporation unit 3 includes at least one flash tank connected to the first outlet of the reaction vessel 2, used to flash the reacted slurry. The steam outlet of the flash tank is connected to the heat exchanger of the preheating tower via a steam pipe 5. The gas-liquid separator is installed on the steam pipe 5 to separate sulfuric acid droplets from the steam.

[0040] In operation, the slurry is first transported to a preheating tower and preheated to a certain temperature before being transported to reactor 2 for reaction. After reaction, the slurry enters a flash tank for cooling and depressurization. The steam generated in the flash tank has a relatively high temperature and is introduced into the preheating tower through steam pipe 5 to preheat the slurry, thus fully utilizing energy. A gas-liquid separator is installed on steam pipe 5 to separate sulfuric acid droplets from the steam. This prevents sulfuric acid from corroding the steam pipe 5 and also allows for the full recovery of sulfuric acid from the steam. Furthermore, only the steam pipe 5 between the gas-liquid separator and the flash tank needs anti-corrosion treatment, reducing the cost of pipeline anti-corrosion treatment.

[0041] Optionally, multiple flash tanks are connected in series, with the pressure in each flash tank decreasing progressively along the direction of slurry flow. This arrangement, by using multiple flash tanks connected in series, gradually reduces the slurry pressure, preventing excessive pressure on each flash tank and thus protecting them.

[0042] Specifically, the flash tank includes a second inlet and a second outlet. Two flash tanks are located in adjacent positions, and the second outlet of the upstream flash tank is connected to the second inlet of the downstream flash tank.

[0043] by Figure 1 For example, the second inlet of the flash tank 31, which performs the first flash evaporation, is connected to the first outlet of the reactor 2. The second outlet of the flash tank 33, which performs the last flash evaporation, is connected to the subsequent slurry processing equipment.

[0044] Specifically, the pressure of the slurry after the reaction is P0, the pressure in the first flash tank 31 is P1, the pressure in the second flash tank 32 is P2, and the pressure in the third flash tank 33 is P3, satisfying the condition P0 > P1 > P2 > P3. After the slurry is discharged from the reactor 1, it first enters the first flash tank 31 for initial depressurization, and then enters the second flash tank 32 and the third flash tank 33 for further depressurization until the discharge requirements are met, and then it is discharged from the third flash tank 33.

[0045] Because the pressure within multiple flash tanks decreases progressively, the temperature of the discharged steam also decreases progressively. Utilizing this principle, multiple preheating towers are connected in series, with each tower corresponding to a flash tank. Along the direction of slurry flow, the temperature of each preheating tower increases progressively. This arrangement allows the slurry to gradually heat up as it flows through the multiple preheating towers, reducing the temperature difference and fully utilizing the thermal energy.

[0046] Specifically, the preheating tower includes a third feed inlet, a third discharge outlet, and a heat exchanger interface. For two adjacent preheating towers, the third discharge outlet of the upstream preheating tower is connected to the third feed inlet of the downstream preheating tower. The heat exchanger interface of the preheating tower is connected to the steam outlet of the corresponding flash tank through steam pipe 5.

[0047] It should be noted that, with Figure 1 For example, the third inlet of the preheating tower 13, which performs the first preheating, is connected to the slurry supply equipment. The third outlet of the preheating tower 11, which performs the final first preheating, is connected to the first inlet of the reactor 2.

[0048] Preferably, multiple preheating towers are connected to multiple flash tanks in a one-to-one correspondence.

[0049] like Figure 1 As shown, in this embodiment, the preheating unit 1 includes three preheating towers connected in series, named first preheating tower 11, second preheating tower 12, and third preheating tower 13 according to their position relative to the reactor 2. The slurry first enters the third preheating tower 13 for the first preheating, then enters the second preheating tower 12 for the second preheating, then enters the first preheating tower 11 for the third preheating, and finally enters the reactor 2 for reaction.

[0050] Similarly, the flash unit 3 also includes three flash tanks connected in series, named first flash tank 31, second flash tank 32, and third flash tank 33 according to their position relative to the reactor 2. The slurry after reaction in the reactor 2 first enters the first flash tank 31 for the first flash evaporation, then enters the second flash tank 32 for the second flash evaporation, and finally enters the third flash tank 33 for the third flash evaporation.

[0051] Steam generated in the first flash tank 31, after passing through the first gas-liquid separator 41 to remove sulfuric acid, enters the heat exchanger of the first preheating tower 11, where it preheats the slurry using its own heat. Steam generated in the second flash tank 32, after passing through the second gas-liquid separator 42 to remove sulfuric acid, enters the heat exchanger of the second preheating tower 12, where it preheats the slurry using its own heat. Steam generated in the third flash tank 33, after passing through the third gas-liquid separator 43 to remove sulfuric acid, enters the heat exchanger of the third preheating tower 13, where it preheats the slurry using its own heat.

[0052] In this embodiment, both the preheating unit 1 and the flash evaporation unit 3 are three-stage structures, containing three corresponding preheating towers and flash evaporators. In other embodiments, other numbers of preheating towers and flash evaporators may be included, with a connection method similar to this embodiment.

[0053] like Figure 2 As shown, in some embodiments, the gas-liquid separator includes a housing 401 and a liquid-separating baffle 402. The housing 401 has a separation chamber and also forms an air inlet 403, an air outlet 404, and a liquid outlet 405 communicating with the separation chamber. The liquid-separating baffle 402 is disposed in the airflow path between the air inlet 403 and the air outlet 404, and can block the steam airflow so that sulfuric acid droplets collide with the liquid-separating baffle 402 and converge into large droplets that flow down. The liquid outlet 405 is located below the liquid-separating baffle 402 and is used to discharge the separated sulfuric acid. The air inlet 403 is connected to the steam outlet of the flash tank, and the air outlet 404 is connected to the heat exchanger interface of the preheating tower.

[0054] In some embodiments, the bottom surface 401 of the housing is a slope, and the outlet 405 is located at the lowest point of the slope so that sulfuric acid can be collected at the outlet 405.

[0055] In some embodiments, the separating baffle 402 has multiple bends to divide the separation chamber into multiple bends in the flow channel. When water vapor passes through the flow channel, sulfuric acid droplets will impact the separating baffle 402 and drip off. This multi-bend structure can effectively separate sulfuric acid droplets from the water vapor, ensuring that the water vapor discharged from the outlet 404 does not contain sulfuric acid.

[0056] In some embodiments, the gas-liquid separator further includes a storage tank 406, with an outlet 405 connected to the upper end of the storage tank 406 and a closable drain port 407 at the lower end. The separated sulfuric acid is collected in the storage tank 406 for temporary storage. When a certain amount is stored, the drain port 407 is opened to discharge it. Since the gas-liquid separator is filled with high-pressure steam, the pressure of the high-pressure steam can automatically push the sulfuric acid out after the drain port 407 is opened.

[0057] In some embodiments, the system further includes a collection tank 6, with a drain port 407 connected to the collection tank 6 via a sulfuric acid pipe. A valve is installed on the sulfuric acid pipe to close the drain port 407. The sulfuric acid separated by each gas-liquid separator can be collected in the same collection tank 6 for centralized collection, recycling, and reuse. It is readily understood that the collection tank 6 includes the necessary discharge structure to discharge the collected sulfuric acid.

[0058] In some embodiments, one or more steam pipes 5 are in contact with the collection tank 6 to heat the sulfuric acid inside the collection tank 6, accelerating the evaporation of water in the collected dilute sulfuric acid and increasing the concentration of sulfuric acid, thereby reducing the workload when reusing this portion of sulfuric acid. Therefore, the collection tank 6 is open or includes an exhaust pipe or similar structure to discharge the evaporated water vapor.

[0059] In practical use, a steam pipe 5 with an appropriate temperature should be selected to heat the sulfuric acid to the suitable temperature. This avoids the situation where the sulfuric acid boils violently and generates acid fumes again. The steam pipe 5 can be in contact with the outer wall of the collection tank 6 or can pass through the inside of the collection tank 6. The heating effect is better when it passes through the inside, but the outer wall of the steam pipe 5 needs to be treated with additional acid corrosion resistance.

[0060] Compared with the prior art, the flash acid recovery system provided in this application is equipped with a gas-liquid separator on the steam pipe 5 of the flash tank to separate and recover the sulfuric acid in the steam. Only the pipeline before the gas-liquid separator needs to be treated with anti-corrosion, which avoids scaling in the preheating tower, reduces the cost of pipeline anti-corrosion treatment, and also reduces the waste of sulfuric acid.

[0061] Furthermore, the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A flash evaporation acid recovery system, characterized in that, include: Reactor (2); The preheating unit (1) includes at least one preheating tower, which is connected to the first feed inlet of the reactor (2) and is used to preheat the slurry. Flash unit (3), the flash unit (3) includes at least one flash tank, the flash tank is connected to the first outlet of the reactor (2), the flash tank is used to flash the slurry after the reaction, and the steam outlet of the flash tank is connected to the heat exchanger of the preheating tower via a steam pipe (5). A gas-liquid separator is installed on the steam pipe (5) and is used to separate sulfuric acid droplets in the steam.

2. The flash evaporation acid reuse system according to claim 1, characterized in that, The flash tanks are arranged in multiple stages connected in series, and the pressure values ​​of the flash tanks decrease step by step along the direction of slurry transfer.

3. The flash evaporation acid reuse system according to claim 2, characterized in that, The preheating towers are arranged in multiple series, and the multiple preheating towers are connected to the multiple flash tanks respectively. The temperature of the preheating towers increases step by step along the direction of slurry transfer.

4. The flash acid recovery system according to claim 3, characterized in that, Each of the preheating towers is connected to a corresponding flash tank.

5. The flash evaporation acid recovery system according to claim 1, characterized in that, The gas-liquid separator includes a shell (401) and a liquid-separating baffle (402). The shell (401) has a separation chamber inside and also forms an air inlet (403), an air outlet (404), and a liquid outlet (405) that communicate with the separation chamber. The liquid-separating baffle (402) is disposed on the airflow path between the air inlet (403) and the air outlet (404). The liquid outlet (405) is located below the liquid-separating baffle (402). The air inlet (403) communicates with the steam outlet of the flash tank, and the air outlet (404) communicates with the heat exchanger interface of the preheating tower.

6. The flash acid recovery system according to claim 5, characterized in that, The bottom surface of the outer shell (401) is a slope, and the liquid outlet (405) is located at the lowest point of the slope.

7. The flash acid recovery system according to claim 5, characterized in that, The liquid separation baffle (402) has multiple bends to divide multiple bends in the separation chamber. When the vapor passes through the flow channels, the sulfuric acid droplets will hit the liquid separation baffle (402) and drip off.

8. The flash acid recovery system according to claim 5, characterized in that, The gas-liquid separator also includes a storage tank (406), the upper end of which is connected to the outlet (405), and the lower end of which has a closable drain port (407).

9. The flash acid recovery system according to claim 8, characterized in that, It also includes a collection tank (6), and the drain port (407) is connected to the collection tank (6) through a sulfuric acid pipe, and a valve is provided on the sulfuric acid pipe.

10. The flash acid recovery system according to claim 9, characterized in that, The steam pipe (5) comes into contact with the collection tank (6) to heat the sulfuric acid inside the collection tank (6).

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