Continuous safe and environment-friendly device for ferric nitrate

Abstract

The utility model belongs to the field of chemical engineering, and particularly relates to a continuous safe environment-friendly device for ferric nitrate. The device comprises a spiral tubular reactor (1), a gas-liquid separator (2), a concentration and crystallization unit (3), a tail gas absorption tower (4) and a tail gas fan (5) connected with the tail gas absorption tower (4), the spiral tubular reactor (1) is connected with the gas-liquid separator (2); the gas-liquid separator (2) is respectively connected with the concentration and crystallization unit (3) and the tail gas absorption tower (4); and the concentration and crystallization unit (3) is connected with the rear end of the spiral tubular reactor (1). The device is a continuous reaction device, the reaction process is stable and easy to control, in addition, the safety is high, and the production efficiency is also effectively improved.

Description

Technical Field

[0001] The utility model belongs to the field of chemical industry, in particular to a continuous safety and environmental protection device for ferric nitrate. Background Art

[0002] Ferric nitrate is a commonly used chemical product. In addition to traditional applications, it can also be used in the preparation of lithium iron phosphate, a new energy material. In the known production process, the production of ferric nitrate is to add nitric acid into a reaction vessel, and then put in iron filings and iron particles to cause them to react chemically to produce ferric nitrate. This reaction generally has the problems described in patent CN 219482651 U, a highly efficient production system for ferric nitrate: the amount of iron filings input during the production process must be controlled. A large amount of iron filings input will lead to a violent reaction and easy explosion. In addition, this production method has a slow reaction and a long waiting time. The feed ratio is difficult to control and other problems.

[0003] CN 109264788 A A device and method for preparing ferric nitrate, although it solves the continuity problem of the reaction process to a certain extent, its essence is still a multi-kettle or multi-tower series mode, and the continuity stability is limited. Patent CN10761572A A high-purity ferric nitrate solution and a continuous preparation method thereof, the continuous process improved by adding ferrous nitrate is essentially to improve the continuity of the crystallization process, rather than the continuity of the nitration process.

[0004] In addition, there are problems such as the one described in patent CN 109264788 A, a device and method for preparing ferric nitrate: conventional ferric nitrate solution preparation devices produce a large amount of nitrogen oxides, which are very harmful to the environment and human body. Therefore, the environmental emission standard requires that nitrogen oxides be controlled at 180mg / m 3 The following. Patent CN104341008B is a method for preparing a low NOx emission ferric nitrate solution. By adding oxygen in the reactor through an oxygen compressor, the emission of nitrogen oxides is reduced. However, the process with reaction safety risks is placed in a pressure vessel, and the intermittent batch feeding has the safety hazards described in patent CN 219482651 U, a high-efficiency ferric nitrate production system. If the reaction gets out of control, it will be more dangerous.

[0005] Therefore, further research and development of the above processes or devices is needed to better improve safety and production efficiency. Utility Model Content

[0006] The purpose of the utility model is to provide a continuous, safe and environmentally friendly device for producing ferric nitrate in response to the problems existing in the current prior art. The device is a continuous reaction device, the reaction process is stable and easy to control, and in addition, it is highly safe and the production efficiency is effectively improved.

[0007] In order to achieve the above utility model purpose, the technical solution of the utility model is as follows:

[0008] A continuous safety and environmental protection device for ferric nitrate comprises a spiral tubular reactor, a gas-liquid separator, a concentration crystallization unit, a tail gas absorption tower and a tail gas blower connected to the tail gas absorption tower; the spiral tubular reactor is connected to the gas-liquid separator; the gas-liquid separator is respectively connected to the concentration crystallization unit and the tail gas absorption tower; the concentration crystallization unit is connected to the rear end of the spiral tubular reactor.

[0009] Furthermore, an iron pellet silo is arranged above the front end of the spiral tubular reactor; a metering screw feeder is arranged below the iron pellet silo, and the iron pellet silo is connected to the spiral tubular reactor via the metering screw feeder.

[0010] Furthermore, an iron pellet inlet is provided at the front end of the spiral tubular reactor, and the iron pellet silo enters the spiral tubular reactor through the iron pellet inlet. The iron pellets or iron filings from the iron pellet silo are fed into the spiral tubular reactor inlet after being measured, and the reaction material iron pellets or iron filings are pushed forward by the spiral and play a stirring role.

[0011] Furthermore, a reaction liquid outlet is arranged in the middle of the spiral tubular reactor, and the spiral tubular reactor is connected to the gas-liquid separator via the reaction liquid outlet.

[0012] Furthermore, a jacket is provided on the spiral tube reactor, and a jacket constant temperature water inlet and a jacket constant temperature water outlet are provided respectively. The jacket is used to maintain a constant reaction temperature to prevent the reaction from self-accelerating and causing danger.

[0013] Furthermore, a circulating mother liquor inlet, an industrial nitric acid inlet and a pure water inlet are respectively arranged at the rear end of the spiral tubular reactor. The raw nitric acid, water, circulating mother liquor and iron particles in the reaction system are in countercurrent contact and react. Water and industrial nitric acid in the reaction system are directly added at the same time, avoiding the emission of nitrogenous gas generated during the nitric acid dilution operation process and reducing the impact of environmental pollution.

[0014] Furthermore, an oxygen inlet is provided on the pipeline connecting the metering screw feeder and the spiral tubular reactor. The oxygen-rich gas is in excess of the amount of nitrogen oxides produced in the reaction process; further, an oxygen-rich gas is provided in front of the spiral tubular reactor as a sealing gas and a reaction raw gas, which not only suppresses the overflow of nitrogen oxides, but also converts nitrogen oxides into nitrogen dioxide, which further participates in the reaction in the system, thereby reducing the amount of nitrogen oxides discharged. The oxygen purity requirement is low, and pure oxygen does not need to be used. Common ordinary pressure swing adsorption air separation units can easily meet the required oxygen content supply conditions.

[0015] Furthermore, a star-shaped feeder is arranged below the iron pellet silo and before the oxygen inlet.

[0016] Furthermore, a filter is arranged at the bottom of the spiral tubular reactor.

[0017] Furthermore, the exhaust fan is connected to the chimney and the exhaust gas is discharged through the chimney.

[0018] Compared with the existing technology, the beneficial effects of the utility model are:

[0019] (I) The spiral tubular reactor is used in the continuous safety and environmental protection device for ferric nitrate, making the reaction process stable and easy to control; the spiral action makes it easier to stir the iron filings or iron particles that are difficult to stir in the kettle reaction mode due to the large specific gravity of iron relative to the nitric acid solution; thereby strengthening the reaction process, accelerating the reaction, and improving efficiency; it also solves the problem of difficult to strengthen mass transfer in packed tower reactors. In addition, the spiral tubular reactor significantly increases the contact surface area between oxygen and the reactants such as nitric acid, nitrogen oxides, and iron, thereby significantly increasing the reaction rate.

[0020] (ii) Oxygen is used as sealing gas in the continuous safety and environmental protection device of ferric nitrate to prevent the leakage of nitrogen oxide gas. Under the spiral tube reaction conditions, the mass transfer efficiency of the material and the contact efficiency of the reaction raw materials are improved. Oxygen oxidizes nitrogen oxide under low pressure, and the pressure <0.1Mpa is significantly different from CN 104341008B; (at 0.1-1.0Mpa) a pressure vessel is used to reduce the pressure level requirements of the equipment;

[0021] (III) In the continuous safety and environmental protection device of ferric nitrate, nitric acid and iron are added continuously, which makes it easy to realize stable and continuous automatic control, reduce labor intensity, and improve the level of occupational safety and health; the raw materials nitric acid, water, and circulating mother liquor in the reaction system contact and react with the iron particles in a countercurrent flow, which minimizes the back-mixing phenomenon, increases the concentration of ferric nitrate in the reactants, and makes the reaction more thorough.

[0022] (iv) Oxygen acts as a gas seal, which not only reduces the pollution caused by nitrogen oxide leakage, but also facilitates the renewal of the iron reaction interface and significantly increases the reaction speed.

[0023] (V) The process of diluting nitric acid by adding water or reusing mother liquor can be carried out in a closed spiral tubular reactor, thus avoiding the nitrogen oxide gas produced by the nitric acid dilution operation in the traditional process to pollute the environment or the need to add special treatment steps; the mother liquor is directly recycled back to the reaction system, and then concentrated after the concentration is increased, saving the energy consumption required for concentration. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a structural schematic diagram of a continuous safety and environmental protection device for ferric nitrate described in the utility model;

[0025] Figure symbols: 1 - spiral tubular reactor, 2 - gas-liquid separator, 3 - concentration crystallization unit, 4 - tail gas absorption tower, 5 - tail gas fan, 6 - iron pellet silo, 7 - metering screw feeder, a - oxygen inlet, b - iron pellet inlet, c - jacket constant temperature water inlet, d - reaction liquid outlet, e - jacket constant temperature water outlet, f - circulating mother liquor inlet, g - industrial nitric acid inlet, h - pure water inlet. DETAILED DESCRIPTION

[0026] All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and / or steps, can be combined in any manner.

[0027] Any feature disclosed in this specification (including claims and abstract), unless otherwise stated, may be replaced by other equivalent or alternative features having similar purposes. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

[0028] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0029] Embodiment 1:

[0030] A continuous safety and environmental protection device for ferric nitrate comprises a spiral tubular reactor 1, a gas-liquid separator 2, a concentration crystallization unit 3, a tail gas absorption tower 4 and a tail gas blower 5 connected to the tail gas absorption tower 4; the spiral tubular reactor 1 is connected to the gas-liquid separator 2; the gas-liquid separator 2 is respectively connected to the concentration crystallization unit 3 and the tail gas absorption tower 4; the concentration crystallization unit 3 is connected to the rear end of the spiral tubular reactor 1.

[0031] Furthermore, an iron pellet silo 6 is arranged above the front end of the spiral tubular reactor 1; a metering screw feeder 7 is arranged below the iron pellet silo 6, and the iron pellet silo 6 is connected to the spiral tubular reactor 1 through the metering screw feeder 7. The adoption of spiral metering feeding makes the device highly continuous, easy to realize automatic control, reduces the work intensity of feeding, and the product quality is continuously stable, avoiding the problem of unstable quality between batches.

[0032] Furthermore, an iron pellet inlet b is provided at the front end of the spiral tubular reactor 1, and the iron pellet silo 6 enters the spiral tubular reactor 1 through the iron pellet inlet b. The iron pellets or iron filings from the iron pellet silo 6 are fed into the spiral tubular reactor inlet after being measured, and the reaction material iron pellets or iron filings are pushed forward by the spiral and play a stirring role.

[0033] Furthermore, a reaction liquid outlet d is provided in the middle of the spiral tubular reactor 1 , and the reaction liquid outlet d is provided with a filter screen for filtering; the spiral tubular reactor 1 is connected to the gas-liquid separator 2 via the reaction liquid outlet d.

[0034] Furthermore, a jacket is provided on the spiral tubular reactor 1, and a jacket constant temperature water inlet c and a jacket constant temperature water outlet e are provided respectively. The jacket is used to maintain a constant reaction temperature, and the constant temperature water is used to transfer heat and maintain a constant temperature to avoid danger caused by self-acceleration of the reaction. Compared with the kettle reaction, the reaction heat is easier to be taken away, and the reaction temperature is stably controlled, which fundamentally solves the safety risk of self-acceleration of the reaction.

[0035] Furthermore, a circulating mother liquor inlet f, an industrial nitric acid inlet g and a pure water inlet h are respectively provided at the rear end of the spiral tubular reactor 1. The raw nitric acid, water, circulating mother liquor and iron particles in the reaction system are in countercurrent contact and react. Water and industrial nitric acid in the reaction system are directly added at the same time, avoiding the emission of nitrogenous gas generated during the nitric acid dilution operation process and reducing the impact of environmental pollution.

[0036] Furthermore, an oxygen inlet a is provided on the pipeline connecting the metering screw feeder 7 and the spiral tubular reactor 1. The oxygen-rich gas is in excess of the amount of nitrogen oxides produced in the reaction process; further, an oxygen-rich gas is provided in front of the spiral tubular reactor as a sealing gas and a reaction raw gas, which not only suppresses the overflow of nitrogen oxides, but also converts nitrogen oxides into nitrogen dioxide, which further participates in the reaction in the system, thereby reducing the amount of nitrogen oxides discharged.

[0037] Furthermore, a star-shaped feeder is provided below the iron pellet silo 6 and before the oxygen inlet a.

[0038] Furthermore, a filter is provided at the bottom of the spiral tubular reactor 1.

[0039] Furthermore, the exhaust gas fan 5 is connected to the chimney and discharged through the chimney.

[0040] In this device, oxygen-enriched sealing gas is used as the device sealing gas, and the oxygen content of the oxygen-enriched sealing gas is required to be >85%.

[0041] The nitric acid, circulating mother liquor and water sent by the metering pump are mixed at the end of the spiral reactor to form the dilute nitric acid mixture required for the reaction. The dilute nitric acid mixture reacts with the iron particles driven by the spiral in the countercurrent under the action of the pump pressure. The dilute mixing heat generated when the nitric acid, water and circulating mother liquor are mixed is sufficient to start the reaction. The heat generated by the further reaction is taken away by the circulating water in the external jacket, ensuring the safety of the reaction; the nitrogen oxides generated during the reaction are oxidized by the oxygen-enriched air into nitrogen dioxide, which further reacts with water to generate nitric acid to continue to participate in the reaction, realizing the recycling of nitrogen oxides; the contact between the oxygen-enriched air and the nitrogen oxides in the spiral tubular reactor, because the surface of the iron particles actually plays a role similar to that of fillers, significantly improves the contact specific surface area, thereby improving the efficiency of the re-oxidation of nitrogen oxides, and also reduces the requirements for oxygen purity. The reaction can be completed without pure oxygen, achieving the reduction of nitrogen oxide emissions, thereby playing a role in reducing the generation of pollutants.

[0042] In order to solve the problem of greater production capacity, multiple groups of spiral tubular reactors can be connected in parallel, which is relatively easy to implement in engineering and is an existing technology.

[0043] The concentration and crystallization unit 3 is a prior art, and is similar to a common process. The mother liquor after separation of the ferric nitrate crystals still contains a certain amount of nitric acid, which is pumped to the end of the reaction tube to further increase the concentration of ferric nitrate while participating in the reaction, which helps to reduce the energy consumption required for concentration; at the same time, it reduces the consumption of nitric acid.

[0044] The tail gas treatment (tail gas absorption tower 4 and tail gas fan 5, etc.) is mainly to further absorb and treat the nitrogen oxides that have not been completely oxidized and the nitrogen oxides that are partially dissolved in the ferric nitrate solution. This part of nitrogen oxides may be separated and precipitated again in the gas-liquid separation tank. This part of the amount will be reduced by 80-95% compared with the common ferric nitrate process due to the above reaction system and process.

[0045] The setting of the exhaust fan realizes the organized discharge of the trace nitrogen oxides that are not completely absorbed, the air that may enter with the oxygen-enriched air and the front-stage system, and some oxygen that is not consumed by the reaction; at the same time, the relatively low pressure of the rear section formed by the fan suction relative to the oxygen-enriched sealing section can effectively control the oxygen-enriched sealing effect.

[0046] The above-mentioned embodiments only express the specific implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the protection scope of the present application. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the technical solution concept of the present application, and these all belong to the protection scope of the present application.

[0047] This background technology section is provided to generally present the context of the present invention, and the work of the currently named inventor, the work to the extent described in this background technology section, and aspects of the description in this section that did not constitute prior art at the time of application are neither explicitly nor implicitly admitted to be prior art of the present invention.

Claims

1. A continuous safety and environmental protection device for ferric nitrate, characterized in that The device comprises a spiral tubular reactor (1), a gas-liquid separator (2), a concentration crystallization unit (3), a tail gas absorption tower (4), and a tail gas fan (5) connected to the tail gas absorption tower (4); the spiral tubular reactor (1) is connected to the gas-liquid separator (2); the gas-liquid separator (2) is respectively connected to the concentration crystallization unit (3) and the tail gas absorption tower (4); and the concentration crystallization unit (3) is connected to the rear end of the spiral tubular reactor (1).

2. The continuous safety and environmental protection device for ferric nitrate according to claim 1, characterized in that: An iron pellet silo (6) is arranged above the front end of the spiral tubular reactor (1); a metering screw feeder (7) is arranged below the iron pellet silo (6), and the iron pellet silo (6) is connected to the spiral tubular reactor (1) via the metering screw feeder (7).

3. The continuous safety and environmental protection device for ferric nitrate according to claim 1 or 2, characterized in that: A reaction liquid outlet (d) is provided in the middle of the spiral tubular reactor (1), and the spiral tubular reactor (1) is connected to the gas-liquid separator (2) via the reaction liquid outlet (d).

4. The continuous safety and environmental protection device for ferric nitrate according to claim 3 is characterized in that: An iron pellet inlet (b) is provided at the front end of the spiral tubular reactor (1), and the iron pellet silo (6) enters the spiral tubular reactor (1) through the iron pellet inlet (b).

5. The continuous safety and environmental protection device for ferric nitrate according to claim 1 or 4, characterized in that: The spiral tubular reactor (1) is provided with a jacket, and is provided with a jacket constant temperature water inlet (c) and a jacket constant temperature water outlet (e).

6. The continuous safety and environmental protection device for ferric nitrate according to claim 5, characterized in that: A circulating mother liquor inlet (f), an industrial nitric acid inlet (g) and a pure water inlet (h) are respectively arranged at the rear end of the spiral tubular reactor (1).

7. The continuous safety and environmental protection device for ferric nitrate according to claim 1 or 6, characterized in that: An oxygen inlet (a) is arranged on the pipeline connecting the metering screw feeder (7) and the spiral tubular reactor (1).

8. The continuous safety and environmental protection device for ferric nitrate according to claim 7, characterized in that: A star-shaped feeder is arranged below the iron pellet silo (6) and before the oxygen inlet (a).

9. The continuous safety and environmental protection device for ferric nitrate according to claim 1 or 8, characterized in that: A filter is arranged at the bottom of the spiral tubular reactor (1).

10. The continuous safety and environmental protection device for ferric nitrate according to claim 9, characterized in that: The exhaust fan (5) is connected to the chimney.

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