Trace anhydrous hydrogen fluoride feeding system

Abstract

The utility model belongs to the technical field of fluorine chemical industry, and particularly relates to a trace anhydrous hydrogen fluoride feeding system. Comprising an anhydrous hydrogen fluoride raw material tank which is arranged on a metering scale, an upper sealing head and a lower sealing head of the anhydrous hydrogen fluoride raw material tank are connected with an inlet valve and an outlet valve respectively, the inlet valve is connected with a nitrogen pipeline, and the outlet valve is connected with a feeding pump through a pipeline. An outlet of the feeding pump is respectively connected with the circulating pipeline, the flow calibration pipeline, the gas-phase reaction feeding pipeline and the liquid-phase reaction feeding pipeline through pipelines, an outlet of the circulating pipeline is connected with an inlet pipeline of the feeding pump, an outlet of the flow calibration pipeline is connected to the recovery tank, and an outlet of the gas-phase reaction feeding pipeline is connected to the fixed bed reactor; and an outlet of the liquid-phase reaction feeding pipeline is connected to the reaction kettle. The system can be simultaneously suitable for liquid-phase and gas-phase fluorination reactions, realizes stable feeding under a high-pressure condition, and meets the requirements of various laboratory fluorination reaction researches on anhydrous hydrogen fluoride feeding.

Description

Technical Field

[0001] The utility model belongs to the technical field of fluorine chemical industry, and in particular relates to a trace anhydrous hydrogen fluoride feeding system. Background Art

[0002] Anhydrous hydrogen fluoride is the most important basic raw material in the fluorine chemical industry. It is mainly used to produce fluorine-containing refrigerants, fluorine-containing fine chemicals and fluorine-containing polymer functional materials. High-purity anhydrous hydrogen fluoride is also widely used as an etchant and cleaning agent for integrated circuits and semiconductors. Anhydrous hydrogen fluoride is a colorless fuming liquid that is easily vaporized under reduced pressure or heated conditions. It has active chemical properties and strong water absorption. When dissolved in water, it will release heat violently and generate highly corrosive hydrofluoric acid. In industrial production, magnetic pumps or centrifugal pumps lined with fluoroplastics are usually used to transport anhydrous hydrogen fluoride.

[0003] However, in a laboratory environment, anhydrous hydrogen fluoride is used in different types of small-scale research reactions. Unlike large-scale feeds in industrial production, small-scale reactions are small in scale and require small amounts of catalyst loading, so trace, stable and precise anhydrous hydrogen fluoride feeds are required. The feed amount needs to reach grams per hour, more specifically, it needs to be equal to or less than 10g / h. At the same time, the anhydrous hydrogen fluoride feed must also meet the requirements of different reaction pressures. Higher reaction pressures require higher anhydrous hydrogen fluoride feed pressures to ensure the normal passage of raw materials. Therefore, a trace, precise and stable anhydrous hydrogen fluoride feed system is an important prerequisite for the normal development of small-scale research.

[0004] At present, commercial feed pumps and flow meters on the market cannot meet the feeding requirements of anhydrous hydrogen fluoride in laboratory tests due to various restrictions. The main problems are as follows: (1) No corrosion resistance. Anhydrous hydrogen fluoride is a strong acidic medium. The use of ordinary feed pumps or flow meters will cause corrosion and leakage, resulting in the inability to feed stably and continuously. At the same time, high-frequency replacement of metering equipment will result in excessive costs and waste of resources. (2) Feed accuracy and range cannot meet the requirements. The pilot experiment requires the feed amount of anhydrous hydrogen fluoride to reach a trace level equal to or less than 10g / h, and it needs to remain stable for a long period of time. However, liquid phase pumps that can achieve trace feeding usually have poor corrosion resistance and cannot meet this requirement. (3) Unable to meet high-pressure feeding requirements. When customizing a feed pump or flow meter made of special anti-corrosion materials, even if the above-mentioned corrosion resistance and trace feeding are met, it is difficult to achieve high-pressure feeding, especially when the feed pressure needs to be higher than 1.0MPa.

[0005] Therefore, in view of the special needs of anhydrous hydrogen fluoride feed in laboratory pilot studies, it is particularly important to develop a trace, precise, stable and high-pressure anhydrous hydrogen fluoride feed system. Utility Model Content

[0006] In view of the above deficiencies in the prior art, the purpose of the utility model is to provide a trace anhydrous hydrogen fluoride feeding system that can be applied to both liquid and gas phase fluorination reactions to achieve stable feeding under high pressure conditions. The system meets the requirements of various laboratory small-scale fluorination reaction studies for anhydrous hydrogen fluoride feeding, ensuring the stability, high efficiency and long-term operation of the reaction system. It effectively avoids experimental interference caused by unstable anhydrous hydrogen fluoride feeding, thereby greatly improving work efficiency.

[0007] The utility model is realized by adopting the following technical solutions:

[0008] The trace anhydrous hydrogen fluoride feeding system comprises an anhydrous hydrogen fluoride raw material tank, which is placed on a weighing scale, and the upper and lower heads of the anhydrous hydrogen fluoride raw material tank are respectively connected with an inlet valve and an outlet valve, the inlet valve is connected with a nitrogen pipeline, the outlet valve is connected with a feed pump through a pipeline, the outlet of the feed pump is respectively connected with a circulation pipeline, a flow calibration pipeline, a gas phase reaction feed pipeline and a liquid phase reaction feed pipeline through pipelines, the outlet of the circulation pipeline is connected with the inlet pipeline of the feed pump, the outlet of the flow calibration pipeline is connected to a recovery tank, the outlet of the gas phase reaction feed pipeline is connected to a fixed bed reactor, and the outlet of the liquid phase reaction feed pipeline is connected to a reactor.

[0009] The material of the anhydrous hydrogen fluoride raw material tank is one of stainless steel 316, stainless steel 304, Monel alloy, Inconel alloy or Hastelloy alloy, preferably stainless steel 316. The tank is lined with a fluoropolymer, specifically polytetrafluoroethylene or ethylene-tetrafluoroethylene copolymer (ETFE), preferably polytetrafluoroethylene. The upper and lower heads are connected to the tank body of the anhydrous hydrogen fluoride raw material tank through flanges.

[0010] The feed pump is one of a centrifugal pump, a screw pump, a Roots pump, a diaphragm pump or a plunger pump, preferably an electromagnetic diaphragm pump, the diaphragm is made of polytetrafluoroethylene, and can provide a feed pressure of 0.1~2.0MPa.

[0011] The circulation pipeline, flow calibration pipeline, gas phase reaction feed pipeline and liquid phase reaction feed pipeline are all equipped with precision needle valves with adjustment scales for controlling the start and stop and flow size of each flow path; the flow calibration pipeline and liquid phase reaction feed pipeline are also equipped with back pressure valves for adjusting the feed pressure.

[0012] The flow calibration pipeline, the gas phase reaction feed pipeline and the liquid phase reaction feed pipeline are provided with pressure gauges.

[0013] The liquid-phase reaction feed pipeline is arranged in more than one group, each group of liquid-phase reaction feed pipelines is respectively connected to different reactors, and the anhydrous hydrogen fluoride delivered by the feed pump is divided into each liquid-phase reaction feed pipeline. The feed pump operates within the rated feed amount working range and has better flow control accuracy. The flow rate of anhydrous hydrogen fluoride entering each liquid-phase reaction feed pipeline can be ≤10g / h.

[0014] The trace anhydrous hydrogen fluoride feeding system also includes a spare pump, a spare return tank, a spare calibration pipeline and a spare feeding pipeline.

[0015] Compared with the prior art, the beneficial effects of the utility model are as follows:

[0016] (1) The trace anhydrous hydrogen fluoride feeding system of the utility model can achieve a feed rate of grams per hour, which can meet the needs of controlling the trace feed of anhydrous hydrogen fluoride in laboratory pilot reactions due to small scale and small catalyst loading;

[0017] (2) The trace anhydrous hydrogen fluoride feeding system described in the utility model has the applicability of both liquid phase and gas phase fluorination reactions, and can meet the requirements of small-scale fluorination reactions under different pressure conditions for anhydrous hydrogen fluoride feeding;

[0018] (3) The trace anhydrous hydrogen fluoride feeding system described in the utility model can adjust the anhydrous hydrogen fluoride feeding amount to the required value for the reaction in advance by being equipped with a flow calibration pipeline, and directly switch to the main feeding pipeline after stabilization, thereby ensuring the accurate feeding of anhydrous hydrogen fluoride in the initial stage of the reaction. In view of the fact that the feeding amount of the fluorinating agent in the initial stage of the fluorination reaction has a significant impact on the performance of the catalyst, this design ensures the rigor and scientific nature of the overall reaction research;

[0019] (4) The trace anhydrous hydrogen fluoride feeding system described in the utility model adopts a corrosion-resistant electromagnetic diaphragm pump for feeding. Through the effective diversion strategy of the circulation pipeline and multi-way feeding, it is ensured that the feeding pump always operates stably within the rated working range, thereby ensuring the stable, efficient and long-term operation of the feeding system and the entire reaction system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic structural diagram of the trace anhydrous hydrogen fluoride feeding system of the utility model;

[0021] In the figure: 1. Anhydrous hydrogen fluoride raw material tank; 2. Weighing scale; 3. Inlet valve; 4. Outlet valve; 5. Nitrogen pipeline; 6. Feed pump; 7. Circulation pipeline; 8. Flow calibration pipeline; 9. Gas phase reaction feed pipeline; 10. Liquid phase reaction feed pipeline; 11. Recovery tank; 12. Fixed bed reactor; 13. Reactor; 14. Precision needle valve; 15. Back pressure valve; 16. Pressure gauge; 17. Spare pump; 18. Spare return tank; 19. Spare calibration pipeline; 20. Spare feed pipeline. DETAILED DESCRIPTION

[0022] In order to make the purpose and technical solution of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings.

[0023] Example 1

[0024] like Figure 1 As shown, the trace anhydrous hydrogen fluoride feeding system comprises an anhydrous hydrogen fluoride raw material tank 1, which is placed on a weighing scale 2, and the upper and lower heads of the anhydrous hydrogen fluoride raw material tank 1 are respectively connected with an inlet valve 3 and an outlet valve 4, and the inlet valve 3 is connected with a nitrogen pipeline 5, which is used to inject nitrogen into the anhydrous hydrogen fluoride raw material tank 1 to ensure that the pressure in the storage tank is maintained at 0.5-1.6 MPa, and the anhydrous hydrogen fluoride in the storage tank is in liquid phase within this pressure range; the outlet valve 4 is connected to the feed pump 6 through a pipeline, and the outlet of the feed pump 6 is respectively connected to the circulation pipeline 7, the flow calibration pipeline 8, the gas phase reaction feed pipeline 9 and the liquid phase reaction feed pipeline 10 through pipelines, the outlet of the circulation pipeline 7 is connected to the inlet pipeline of the feed pump 6, the outlet of the flow calibration pipeline 8 is connected to the recovery tank 11, the outlet of the gas phase reaction feed pipeline 9 is connected to the fixed bed reactor 12, and the outlet of the liquid phase reaction feed pipeline 10 is connected to the reactor 13.

[0025] The material of the anhydrous hydrogen fluoride raw material tank 1 is stainless steel 316, which is lined with polytetrafluoroethylene, and the upper and lower heads are connected to the tank body of the anhydrous hydrogen fluoride raw material tank 1 through flanges.

[0026] The feed pump 6 is an electromagnetic diaphragm pump.

[0027] The circulation pipeline 7 , flow calibration pipeline 8 , gas phase reaction feed pipeline 9 and liquid phase reaction feed pipeline 10 are all provided with precision needle valves 14 , and the flow calibration pipeline 8 and liquid phase reaction feed pipeline 10 are also provided with back pressure valves 15 .

[0028] The flow calibration pipeline 8 , the gas phase reaction feed pipeline 9 and the liquid phase reaction feed pipeline 10 are provided with pressure gauges 16 .

[0029] The liquid-phase reaction feed pipelines 10 are arranged in three groups, and each group of liquid-phase reaction feed pipelines 10 is connected to different reaction kettles 13 .

[0030] The trace anhydrous hydrogen fluoride feeding system also includes a standby pump 17, a standby return tank 18, a standby calibration pipeline 19 and a standby feed pipeline 20; the inlet of the standby pump 17 is connected to the outlet valve 4 through a pipeline, and the outlet of the standby feed pipeline 20 is connected to the fixed bed reactor 12.

[0031] In the liquid phase fluorination reaction of preparing 1,2-dichloro-3,3,3-trifluoropropene using 1,1,1,2,2,3-hexachloropropane as a reaction raw material, anhydrous hydrogen fluoride as a fluorination reagent, and antimony fluoride chloride as a catalyst, the feed of anhydrous hydrogen fluoride is controlled by using the trace anhydrous hydrogen fluoride feed system, and the specific process is as follows:

[0032] First, anhydrous hydrogen fluoride enters the electromagnetic diaphragm pump from the anhydrous hydrogen fluoride raw material tank 1 through the opened outlet valve 4. The electromagnetic diaphragm pump delivers anhydrous hydrogen fluoride to the outlet pipeline at a stable flow rate, and then diverts it to three liquid-phase reaction feed pipelines 10. Since the feed conditions of the three reactors 13 are the same, that is, the anhydrous hydrogen fluoride feed amount required for each reactor 13 is one-third of the total amount, the precision needle valve 14 and the back pressure valve 15 on each liquid-phase reaction feed pipeline 10 are precisely adjusted to ensure that their openings are consistent, so that the pressure gauge 16 on each liquid-phase reaction feed pipeline 10 shows a pressure of 1.0MPa, and the reaction pressure in the reactor 13 is maintained at 0.85MPa.

[0033] During the feeding process, the feeding amount of the electromagnetic diaphragm pump is precisely controlled to 30 g / h, ensuring that each liquid phase reaction feeding pipeline 10 stably supplies the respective connected reactors 13 with a flow rate of 10 g / h.

[0034] Example 2

[0035] The trace anhydrous hydrogen fluoride feeding system is the same as that in Example 1, except that:

[0036] In the process of gas phase fluorination reaction using 1,1,1-trifluoropropene, anhydrous hydrogen fluoride and chlorine as raw materials to generate a mixture of 2,3-dichloro-1,1,1-trifluoropropane, 2-chloro-1,1,1,2-tetrafluoropropane and 2-chloro-1,1,1-trifluoropropene, the feed of anhydrous hydrogen fluoride is controlled by using the trace anhydrous hydrogen fluoride feed system, and the specific process is as follows:

[0037] First, anhydrous hydrogen fluoride enters the electromagnetic diaphragm pump from the anhydrous hydrogen fluoride raw material tank 1 through the opened outlet valve 4. Then it enters the circulation pipeline 7 and the flow calibration pipeline 8 through the outlet pipeline of the electromagnetic diaphragm pump, while ensuring that the gas phase reaction feed pipeline 9 is closed, and the feed pressure is controlled to be equal to the reaction pressure by adjusting the precision needle valve 14 on the circulation pipeline 7 and the flow calibration pipeline 8 and the back pressure valve 15 on the flow calibration pipeline 8, and the anhydrous hydrogen fluoride used for flow calibration is collected by the recovery tank 11.

[0038] After stabilization, adjust the opening of the precision needle valve 14 on the gas phase reaction feed pipeline 9 to be the same as the opening of the precision needle valve 14 on the flow calibration pipeline 8, then close the flow calibration pipeline 8, open the gas phase reaction feed pipeline 9 and start feeding.

[0039] In order to examine the stability of the catalyst and maintain the trace, stable and long-term feeding of anhydrous hydrogen fluoride, the system adopts the design principle of one backup and one use. That is, when one gas phase reaction feed pipeline 9 and the corresponding flow calibration pipeline 8 are in use, the other backup feed pipeline 20 and the corresponding backup calibration pipeline 19 are used as backup, so as to ensure that even if the main pipeline fails, it can be quickly switched to the backup pipeline, so as not to affect the continuous reaction.

Claims

1. A trace anhydrous hydrogen fluoride feeding system, characterized in that: The invention comprises an anhydrous hydrogen fluoride raw material tank (1), wherein the anhydrous hydrogen fluoride raw material tank (1) is placed on a weighing scale (2), wherein the upper and lower heads of the anhydrous hydrogen fluoride raw material tank (1) are respectively connected with an inlet valve (3) and an outlet valve (4), wherein the inlet valve (3) is connected with a nitrogen pipeline (5), wherein the outlet valve (4) is connected with a feed pump (6) via a pipeline, wherein the outlet of the feed pump (6) is respectively connected with a circulation pipeline (7), a flow calibration pipeline (8), a gas phase reaction feed pipeline (9) and a liquid phase reaction feed pipeline (10) via pipelines, wherein the outlet of the circulation pipeline (7) is connected with the inlet pipeline of the feed pump (6), the outlet of the flow calibration pipeline (8) is connected with a recovery tank (11), the outlet of the gas phase reaction feed pipeline (9) is connected with a fixed bed reactor (12), and the outlet of the liquid phase reaction feed pipeline (10) is connected with a reactor (13).

2. The trace anhydrous hydrogen fluoride feeding system according to claim 1, characterized in that: The anhydrous hydrogen fluoride raw material tank (1) is lined with a fluoropolymer, and the upper and lower heads are connected to the tank body of the anhydrous hydrogen fluoride raw material tank (1) via flanges respectively.

3. The trace anhydrous hydrogen fluoride feeding system according to claim 1, characterized in that: The feed pump (6) is one of a centrifugal pump, a screw pump, a Roots pump, a diaphragm pump or a plunger pump.

4. The trace anhydrous hydrogen fluoride feeding system according to claim 1, characterized in that: The circulation pipeline (7), flow calibration pipeline (8), gas phase reaction feed pipeline (9) and liquid phase reaction feed pipeline (10) are all provided with precision needle valves (14), and the flow calibration pipeline (8) and liquid phase reaction feed pipeline (10) are also provided with back pressure valves (15).

5. The trace anhydrous hydrogen fluoride feeding system according to claim 1, characterized in that: The flow calibration pipeline (8), the gas phase reaction feed pipeline (9) and the liquid phase reaction feed pipeline (10) are provided with pressure gauges (16).

6. The trace anhydrous hydrogen fluoride feeding system according to claim 1, characterized in that: The liquid-phase reaction feed pipeline (10) is arranged as more than one group, and each group of liquid-phase reaction feed pipelines (10) is respectively connected to different reaction kettles (13).

7. The trace anhydrous hydrogen fluoride feeding system according to claim 1, characterized in that: It also includes a spare pump (17), a spare return tank (18), a spare calibration pipeline (19) and a spare feed pipeline (20).

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