Waste hydrofluoric acid concentration and purification system

Abstract

The utility model discloses a waste hydrofluoric acid concentration and purification system, which belongs to the field of waste acid recovery and comprises a waste hydrofluoric acid source, a circulating evaporation unit and a negative pressure concentration tower in the material advancing direction, the circulating evaporation unit comprises an evaporator and a negative pressure separator, and a top discharge port of the evaporator is connected to the negative pressure separator; the bottom discharge hole is connected to a crystallization unit; a bottom discharge hole of the negative-pressure separator is connected to the evaporator, and a top discharge hole of the negative-pressure separator is connected to the middle part of the negative-pressure concentration tower; a bottom discharge port of the negative-pressure concentration tower is a recycled acid outlet, a top discharge port is connected to the negative-pressure condenser, and a discharge port of the negative-pressure condenser is a wastewater outlet. According to the system, waste hydrofluoric acid can be treated into high-concentration and high-purity hydrofluoric acid, and the high-concentration and high-purity hydrofluoric acid is discharged from the bottom of the negative-pressure concentration tower, collected and reused for production, so that useful hydrofluoric acid resources in the waste hydrofluoric acid can be extracted, useful industrial salts in the waste hydrofluoric acid can be recycled, and the resources can be effectively utilized.

Description

Technical Field

[0001] The utility model relates to a waste hydrofluoric acid concentration and purification system, belonging to the field of waste acid recovery. Background Art

[0002] At present, the general method for treating waste acid containing hydrofluoric acid is the neutralization precipitation method. First, the pH of the pickling waste acid is adjusted to near neutral with sodium hydroxide, and then calcium hydroxide and calcium chloride are reacted with the pickling waste acid to form a precipitate to obtain calcium fluoride. However, the neutralization precipitation method consumes the acid in the wastewater, resulting in the direct waste of hydrofluoric acid in the wastewater. The existing waste hydrofluoric acid treatment system cannot perform resource-based treatment on waste hydrofluoric acid and cannot extract useful resources from waste hydrofluoric acid. Summary of the Utility Model

[0003] In order to overcome the deficiencies of the prior art, the utility model provides a waste hydrofluoric acid concentration and purification system, which can recover hydrofluoric acid and other useful salts in waste hydrofluoric acid.

[0004] The technical solution adopted by the utility model to solve its technical problems is:

[0005] A waste hydrofluoric acid concentration and purification system, including a waste hydrofluoric acid source, a circulating evaporation unit and a negative pressure concentration tower in the direction of material flow. The circulating evaporation unit includes an evaporator and a negative pressure separator. The top discharge port of the evaporator is connected to the negative pressure separator, and the bottom discharge port is connected to a crystallization unit; the bottom discharge port of the negative pressure separator is connected to the evaporator, and the top discharge port is connected to the middle part of the negative pressure concentration tower; the bottom discharge port of the negative pressure concentration tower is a recovered acid outlet, and the top discharge port is connected to a negative pressure condenser, and the discharge port of the negative pressure condenser is a wastewater outlet.

[0006] The waste hydrofluoric acid concentration and purification system provided by this application can treat waste hydrofluoric acid into high-concentration and high-purity hydrofluoric acid, which is discharged from the bottom of the negative pressure concentration tower, collected and reused in production. Thus, the useful hydrofluoric acid resources in waste hydrofluoric acid can be extracted, and the useful industrial salts in waste hydrofluoric acid can be recovered, effectively utilizing resources.

[0007] Further, a preheating unit is arranged between the waste hydrofluoric acid source and the circulating evaporation unit. The preheating unit includes a preheater and a preheating tank for feeding the preheater. The preheater is provided with a preheating return pipe for returning to the preheating tank.

[0008] Further, the feed port of the preheating tank is connected to the waste hydrofluoric acid source, and the preheater discharges materials to the circulating evaporation unit.

[0009] Further, the preheater is connected with an evaporation feed pipe for feeding materials to the upper part of the evaporator and the upper part of the negative pressure separator simultaneously.

[0010] Furthermore, the evaporator is provided with a first heating mechanism for introducing a first heating medium, and the preheater is provided with a second heating mechanism for introducing a second heating medium.

[0011] Furthermore, a condensate water pipe leading from the first heating mechanism to the second heating mechanism is arranged between the evaporator and the preheater, the first heating medium is boiler steam, and the second heating medium is the condensate water of the boiler steam.

[0012] Furthermore, the waste hydrofluoric acid concentration and purification system further includes a cooling water tower, and the negative pressure condenser is provided with a first cooling mechanism communicated with the cooling water tower.

[0013] Furthermore, the crystallization unit includes a negative pressure crystallizer, an acid mist absorber and a negative pressure filter. The feed port of the negative pressure crystallizer is connected to the bottom discharge port of the evaporator, and the bottom discharge port of the negative pressure crystallizer is connected to the feed port of the negative pressure filter; the feed port of the acid mist absorber is connected to the negative pressure crystallizer, and the bottom discharge port of the acid mist absorber is an acid water outlet; the negative pressure crystallizer is provided with a second cooling mechanism communicated with the cooling water tower, and the acid mist absorber is provided with a third cooling mechanism communicated with the cooling water tower.

[0014] Furthermore, the crystallization unit further includes an acid water collection tank, a second vacuum machine and a second pressure stabilizing tank connected to the second vacuum machine. The bottom discharge port of the negative pressure crystallizer is connected in series to the second pressure stabilizing tank through the negative pressure filter, and the bottom discharge port of the acid mist absorber is connected in series to the second pressure stabilizing tank through the acid water collection tank.

[0015] Furthermore, the negative pressure of the negative pressure separator, the negative pressure concentration tower and the negative pressure condenser is provided by a first vacuum machine and a first pressure stabilizing tank connected to the first vacuum machine, and the circulating evaporation unit is connected in series to the first pressure stabilizing tank through the negative pressure concentration tower and the negative pressure condenser in sequence.

[0016] The beneficial effects of the present utility model are as follows: The waste hydrofluoric acid concentration and purification system of the present utility model can use the circulating evaporation unit to perform cyclic cumulative evaporation on waste hydrofluoric acid, intercept soluble salts and impurities. The purified dilute hydrofluoric acid enters the negative pressure concentration tower, and the negative pressure concentration tower further concentrates the dilute hydrofluoric acid and separates the acid water. The weak acidic water vapor at the top of the tower is condensed into weakly acidic wastewater by the negative pressure condenser, and highly pure hydrofluoric acid is recovered at the bottom of the tower, which can be directly used for industrial pickling. The soluble salts intercepted by the circulating evaporation unit are processed in the crystallization unit to generate industrially valuable industrial salts.

[0017] Other features and advantages of the present application will be described in the subsequent specification, and in part will be obvious from the specification, or will be understood by implementing the present application. The objectives and other advantages of the present application can be achieved and obtained by the structures specifically pointed out in the written specification and the drawings. Description of the Drawings

[0018] Figure 1 It is one of the schematic diagrams showing the connection relationships of various devices of a waste hydrofluoric acid concentration and purification system provided by an embodiment of the present application.

[0019] Figure 2 It is another schematic diagram showing the connection relationships of various devices of a waste hydrofluoric acid concentration and purification system provided by an embodiment of the present application.

[0020] Figure 3 It is yet another schematic diagram showing the connection relationships of various devices of a waste hydrofluoric acid concentration and purification system provided by an embodiment of the present application.

[0021] Figure 4 It is still another schematic diagram showing the connection relationships of various devices of a waste hydrofluoric acid concentration and purification system provided by an embodiment of the present application.

[0022] Figure 5 It is yet again a schematic diagram showing the connection relationships of various devices of a waste hydrofluoric acid concentration and purification system provided by an embodiment of the present application.

[0023] Reference Signs: 1, waste hydrofluoric acid storage tank; 11, first feed pump; 12, second feed pump; 21, preheating tank; 22, preheater; 221, preheating return pipe; 31, evaporator; 311, condensate pipe; 32, negative pressure separator; 4, negative pressure concentration tower; 41, recovered acid collection tank; 5, negative pressure condenser; 51, wastewater collection tank; 61, negative pressure crystallizer; 62, negative pressure filter; 63, acid mist absorber; 631, acid water collection tank; 7, first vacuum pump; 71, first pressure stabilizing tank; 8, second vacuum pump; 81, second pressure stabilizing tank; 9, cooling water tower. Detailed Embodiments

[0024] The following details the embodiments of the present utility model. Examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary only for explaining the present utility model and should not be construed as limiting the present utility model.

[0025] The following disclosure provides many different embodiments or examples for implementing different structures of the present utility model. To simplify the disclosure of the present utility model, the components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present utility model. In addition, the present utility model may repeat reference numerals and / or reference letters in different examples. Such repetition is for the purpose of simplification and clarity and does not itself indicate the relationship between the various embodiments and / or settings discussed.

[0026] Referring to Figure 1 , an embodiment of the present application provides a waste hydrofluoric acid concentration and purification system, which includes a waste hydrofluoric acid source, a circulating evaporation unit, and a negative pressure concentration tower 4 in the direction of material flow. The circulating evaporation unit includes an evaporator 31 and a negative pressure separator 32. The top discharge port of the evaporator 31 is connected to the negative pressure separator 32, and the bottom discharge port is connected to a crystallization unit; the bottom discharge port of the negative pressure separator 32 is connected to the evaporator 31, and the top discharge port is connected to the middle part (divided by height) of the negative pressure concentration tower 4; the bottom discharge port of the negative pressure concentration tower 4 is a recycled acid outlet, and the top discharge port is connected to a negative pressure condenser 5. The discharge port of the negative pressure condenser 5 is a waste water outlet.

[0027] After the waste hydrofluoric acid enters the circulating evaporation unit, the valve for feeding (not shown in the figure) of the circulating evaporation unit is closed. The waste hydrofluoric acid circulates between the evaporator 31 and the negative pressure separator 32. The gaseous components in the evaporator 31 enter the negative pressure separator 32, and the liquid components in the negative pressure separator 32 flow back to the evaporator 31. During the above cycle, the gaseous components with lower density in the negative pressure separator 32 enter the negative pressure concentration tower 4. The weak acidic water vapor at the top of the negative pressure concentration tower 4 is condensed into weak acidic waste water by the negative pressure condenser 5 and then collected and treated, while the bottom of the tower is high-concentration and high-purity hydrofluoric acid. In actual implementation, the temperature of the negative pressure separator 32 is controlled at 40°C to 68°C, and the negative pressure is controlled at -0.06 MPa to -0.08 MPa; the temperature of the negative pressure concentration tower 4 is controlled at 50°C to 60°C, and the pressure is similar to that of the negative pressure separator 32.

[0028] Specifically, the waste hydrofluoric acid source may be a waste hydrofluoric acid pool. As in the embodiment shown in Figure 2 , the waste hydrofluoric acid source is a waste hydrofluoric acid storage tank 1, and a total of two feed pumps, namely a first feed pump 11 and a second feed pump 12, are used for feeding. At the recycled acid outlet of the negative pressure concentration tower 4, a recycled acid collection tank 41 can be connected. At the waste water outlet of the negative pressure condenser 5, a waste water collection tank 51 can be connected.

[0029] Referring to Figure 2, in this embodiment, a preheating unit is provided between the waste hydrofluoric acid source and the circulating evaporation unit. The preheating unit includes a preheater 22 and a preheating tank 21 for feeding the preheater 22. The preheater 22 is provided with a preheating return pipe 221 that returns to the preheating tank 21. Preheating the waste hydrofluoric acid is beneficial to the rapid evaporation of the waste hydrofluoric acid after it enters the evaporator 31. In actual implementation, the preheating temperature is between 25°C and 35°C.

[0030] Specifically, the feed port of the preheating tank 21 is connected to the waste hydrofluoric acid source, and the preheater 22 discharges materials to the circulating evaporation unit.

[0031] In a preferred embodiment, the preheater 22 is connected with an evaporation feed pipe for feeding the upper part of the evaporator 31 and the upper part of the negative pressure separator 32 simultaneously. Such a setting has two advantages. One is that each feed can wash the precipitates on the inner walls of the evaporator 31, the negative pressure separator 32, and the circulating pipeline between the two; the other is to reduce the number of flange openings of the negative pressure separator 32, which is beneficial to reducing the equipment maintenance frequency.

[0032] In addition to directly heating with electric heating wires, the evaporator 31 and the preheater 22 can also use central heating with boiler steam. For example, the evaporator 31 has a first heating mechanism for introducing a first heating medium, and the preheater 22 has a second heating mechanism for introducing a second heating medium. In some embodiments, the first heating medium and the second heating medium can both be boiler steam. These heating mechanisms are usually arranged on the surface of the equipment, and heat transfer is achieved through the partition wall. The structure of heat transfer through the partition wall is not shown in detail in the figure.

[0033] In a preferred embodiment, referring to Figure 3 , a condensate water pipe 311 leading from the first heating mechanism to the second heating mechanism is provided between the evaporator 31 and the preheater 22. The first heating medium is boiler steam, and the second heating medium is the condensate water after the phase change of the first heating medium. It can effectively utilize the residual heat after heating the evaporator 31 with boiler steam to heat the preheater 22, which is beneficial to saving energy. It should be noted that the condensate water pipe 311 is filled with the condensate water of the boiler steam and is not connected to the hydrofluoric acid steam in the evaporator 31. In the specification drawings, for the convenience of distinction, the solid arrow indicates the traveling direction of the waste hydrofluoric acid and the materials derived from the waste hydrofluoric acid; the hollow arrow indicates the new incoming direction of the working media such as cooling water and boiler steam. The line intersection with a semi-circular arc indicates that they are not directly connected, and the line intersection with a direct cross or "T" intersection indicates that they are connected to each other.

[0034] Referring to Figure 4 , the waste hydrofluoric acid concentration and purification system further includes a cooling water tower 9, and the negative pressure condenser 5 has a first cooling mechanism connected to the cooling water tower 9.

[0035] The crystallization unit includes a negative-pressure crystallizer 61, an acid mist absorber 63, and a negative-pressure filter 62. The feed inlet of the negative-pressure crystallizer 61 is connected to the bottom discharge outlet of the evaporator 31, and the bottom discharge outlet of the negative-pressure crystallizer 61 is connected to the feed inlet of the negative-pressure filter 62; the feed inlet of the acid mist absorber 63 is connected to the negative-pressure crystallizer 61, and the bottom discharge outlet of the acid mist absorber 63 is the acid water outlet; the negative-pressure crystallizer 61 has a second cooling mechanism communicated with the cooling water tower 9, and the acid mist absorber 63 has a third cooling mechanism communicated with the cooling water tower 9. The cooling water tower 9 supplies cooling uniformly to the negative-pressure condenser 5, the negative-pressure crystallizer 61, and the acid mist absorber 63. These cooling mechanisms are usually arranged on the equipment surface and achieve cooling by means of wall heat transfer. The structure of wall heat transfer is not drawn in detail in the figure.

[0036] After the negative-pressure crystallizer 61 cools and crystallizes, the solid enters the negative-pressure filter 62 from the bottom discharge outlet for recovery, and the obtained industrial salts are fluorides, fluorosilicates, etc. The acid mist during the crystallization process is sucked by negative pressure into the acid mist absorber 63 for cooling and absorption. When necessary, an adsorbent can be filled in the acid mist absorber 63. The acid water outlet of the acid mist absorber 63 can be connected to an acid water collection tank 631. During actual implementation, the temperature of the negative-pressure crystallizer 61 is controlled at 20°C to 28°C, and the negative pressure is controlled at -0.03 MPa to -0.05 MPa.

[0037] If a negative-pressure system is provided for each device that requires negative pressure, the control is difficult and the cost is relatively high. Preferably, referring to Figure 5 , the crystallization unit further includes an acid water collection tank 631, a second vacuum machine 8, and a second pressure stabilizing tank 81 connected to the second vacuum machine 8. The bottom discharge outlet of the negative-pressure crystallizer 61 is connected in series to the second pressure stabilizing tank 81 through the negative-pressure filter 62, and the bottom discharge outlet of the acid mist absorber 63 is connected in series to the second pressure stabilizing tank 81 through the acid water collection tank 631.

[0038] Similarly, continuing to refer to Figure 5 , the negative pressure of the negative-pressure separator 32, the negative-pressure concentration tower 4, and the negative-pressure condenser 5 is provided by the first vacuum machine 7 and the first pressure stabilizing tank 71 connected to the first vacuum machine 7. The circulating evaporation unit is connected in series to the first pressure stabilizing tank 71 through the negative-pressure concentration tower 4 and the negative-pressure condenser 5 in sequence. It should be noted that after the preheating unit feeds the circulating evaporation unit, the valve for the preheating unit to feed the circulating evaporation unit needs to be closed, so as to ensure the negative pressure of the negative-pressure separator 32, the negative-pressure concentration tower 4, and the negative-pressure condenser 5, and the negative-pressure system can be saved.

[0039] In the description of this specification, the descriptions with reference to terms such as "one embodiment", "certain embodiments", "schematic embodiments", "examples", "specific examples", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present utility model. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiments or examples. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0040] The above are the preferred embodiments of the present utility model. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present utility model, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present utility model.

Claims

1. A waste hydrofluoric acid concentration and purification system, characterized in that: According to the direction of material movement, it includes a waste hydrofluoric acid source, a circulating evaporation unit and a negative pressure concentration tower. The circulating evaporation unit includes an evaporator and a negative pressure separator. The top discharge port of the evaporator is connected to the negative pressure separator, and the bottom discharge port is connected to the crystallization unit; the bottom discharge port of the negative pressure separator is connected to the evaporator, and the top discharge port is connected to the middle part of the negative pressure concentration tower; the bottom discharge port of the negative pressure concentration tower is the acid recovery outlet, and the top discharge port is connected to the negative pressure condenser, and the discharge port of the negative pressure condenser is the wastewater outlet.

2. The waste hydrofluoric acid concentration and purification system according to claim 1, characterized in that: A preheating unit is arranged between the waste hydrofluoric acid source and the circulating evaporation unit. The preheating unit comprises a preheater and a preheating tank for feeding the preheater. The preheater is provided with a preheating reflux pipe for reflux to the preheating tank.

3. The waste hydrofluoric acid concentration and purification system according to claim 2, characterized in that: The feed inlet of the preheating tank is connected to the waste hydrofluoric acid source, and the preheater discharges material to the circulating evaporator unit.

4. The waste hydrofluoric acid concentration and purification system according to claim 3, characterized in that: The preheater is connected with an evaporation feed pipe for simultaneously feeding materials to the upper part of the evaporator and the upper part of the negative pressure separator.

5. The waste hydrofluoric acid concentration and purification system according to claim 2, characterized in that: The evaporator has a first heating device for passing a first heating medium, and the preheater has a second heating device for passing a second heating medium.

6. The waste hydrofluoric acid concentration and purification system according to claim 5, characterized in that: A condensed water pipe leading from the first heating mechanism to the second heating mechanism is provided between the evaporator and the preheater. The first heating medium is boiler steam, and the second heating medium is condensed water of the boiler steam.

7. The waste hydrofluoric acid concentration and purification system according to claim 1, characterized in that: It also includes a cooling water tower, and the negative pressure condenser has a first cooling mechanism connected to the cooling water tower.

8. The waste hydrofluoric acid concentration and purification system according to claim 7, characterized in that: The crystallization unit includes a negative pressure crystallizer, an acid mist absorber and a negative pressure filter. The feed port of the negative pressure crystallizer is connected to the bottom discharge port of the evaporator, and the bottom discharge port of the negative pressure crystallizer is connected to the feed port of the negative pressure filter; the feed port of the acid mist absorber is connected to the negative pressure crystallizer, and the bottom discharge port of the acid mist absorber is an acid water outlet; the negative pressure crystallizer has a second cooling mechanism connected to the cooling water tower, and the acid mist absorber has a third cooling mechanism connected to the cooling water tower.

9. The waste hydrofluoric acid concentration and purification system according to claim 8, characterized in that: The crystallization unit also includes an acid water collection tank, a second vacuum machine and a second pressure-stabilizing tank connected to the second vacuum machine. The bottom discharge port of the negative pressure crystallizer is connected in series to the second pressure-stabilizing tank via the negative pressure filter, and the bottom discharge port of the acid mist absorber is connected in series to the second pressure-stabilizing tank via the acid water collection tank.

10. The waste hydrofluoric acid concentration and purification system according to claim 1, characterized in that: The negative pressure of the negative pressure separator, the negative pressure concentration tower and the negative pressure condenser is provided by a first vacuum machine and a first pressure stabilizing tank connected to the first vacuum machine, and the circulating evaporation unit is connected in series to the first pressure stabilizing tank via the negative pressure concentration tower and the negative pressure condenser in sequence.

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