A fluorinated phosphate system tail gas separation and purification device

Abstract

The application relates to the fluorinated phosphate manufacturing field, and provides a fluorinated phosphate system tail gas separation and purification device, which comprises a fluorinated phosphate device, a tail gas compressor, a tail gas cooler, a nitrogen gas cooler, a hydrogen fluoride cooler, a hydrogen chloride cooler, a nitrogen gas separator, a hydrogen fluoride separator, a hydrogen chloride separator, a nitrogen gas storage tank, a hydrogen fluoride storage tank and a hydrogen chloride storage tank.The application has low pressure after tail gas compression, does not need high-pressure equipment, is high in safety, is cooled to-20 DEG C to-45 DEG C by using the cold source of the fluorinated phosphate device after tail gas compression, does not need to increase new refrigerants, nitrogen gas and hydrogen fluoride can be recycled and utilized through separation and purification, production cost is reduced, enterprise competitive advantage is improved, mixed acid is not generated through separation and purification, and nitrogen gas, hydrogen fluoride and hydrogen chloride are completely separated.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fluorinated phosphate manufacturing, in particular to a fluorinated phosphate system tail gas separation and purification device. BACKGROUND

[0002] Fluorinated phosphate is a key material for new energy battery electrolyte. With the progress of science and technology and the improvement of people's living standards, the electronic information industry and the power automobile industry are developing rapidly, the new energy market demand is booming, and the demand for fluorinated phosphate is increasing day by day.

[0003] The general reaction formula of fluorinated phosphate is: PC15+5HF+XF=XPF6+5HCI, and X can be lithium, sodium and other elements. In the production process.

[0004] Phosphorus pentachloride and hydrogen fluoride are discharged in the production of phosphorus pentafluoride. Hydrogen chloride and hydrogen fluoride, nitrogen sealing nitrogen gas, hydrogen fluoride cannot be completely recovered by condensation due to the influence of a large amount of nitrogen gas. The remaining nitrogen gas, hydrogen chloride, and uncondensed hydrogen fluoride are usually treated by water absorption. The hydrogen chloride and hydrogen fluoride are removed, and a large amount of mixed acid is generated.

[0005] The traditional treatment method mainly has the following disadvantages:

[0006] (1) The tail gas containing hydrogen fluoride, hydrogen chloride and nitrogen is condensed to form a large amount of hydrogen fluoride and hydrogen chloride liquid droplets less than 10 microns, which cannot be separated from the uncondensed nitrogen by conventional means;

[0007] (2) A large amount of hydrogen fluoride is carried by nitrogen to the tail gas absorption treatment, which cannot recover hydrogen fluoride and hydrogen chloride by condensation, resulting in serious waste of raw and auxiliary materials and high production cost;

[0008] (3) Water absorption is used to absorb hydrogen fluoride and hydrogen chloride. The mixed acid after absorption has high corrosion resistance requirements for equipment materials, generates a large amount of mixed acid, and has limitations in treatment, and enterprises face great environmental pressure. SUMMARY

[0009] In view of the shortcomings of the prior art, the present application provides a fluorinated phosphate system tail gas separation and purification device, which solves the problems that the traditional treatment method cannot separate the condensed hydrogen fluoride and hydrogen chloride from the uncondensed nitrogen, recovers hydrogen fluoride and hydrogen chloride by condensation, causes serious waste of raw and auxiliary materials, has high production cost, generates a large amount of mixed acid, has limitations in treatment, and enterprises face great environmental pressure.

[0010] To achieve the above purpose, the present application is realized by the following technical scheme: a fluorinated phosphate system tail gas separation and purification device, comprising:

[0011] A compressor for pressurizing the tail gas to 0.3-1.0 MPa.

[0012] A condenser for cooling the pressurized tail gas to condense the hydrogen fluoride and hydrogen chloride in the tail gas into liquid droplets.

[0013] A separation tank for separating the liquid droplets formed after condensation from the nitrogen.

[0014] A coalescer for filtering and separating the hydrogen fluoride and hydrogen chloride liquid droplets smaller than 10 μm into large droplets after trapping, and recycling the separated liquid into a buffer tank for temporary storage.

[0015] A rectifying column for purifying the liquid temporarily stored in the buffer tank.

[0016] Preferably, the compressor is an oil-free compressor, and the tail gas is pressurized to 0.5-0.8 MPa.

[0017] Preferably, a demisting wire mesh is used inside the separation tank to separate the gas and liquid.

[0018] Preferably, the coalescer is made of stainless steel, and the filter core is made of a metal sintered filter screen with a filtering accuracy of 0.8-1.2 μm.

[0019] Preferably, the rectifying column has 10-30 trays, and the reflux ratio is 0.2-3, wherein the hydrogen chloride is recovered from the top of the column, and the hydrogen fluoride is recovered from the bottom of the column.

[0020] Preferably, the rectifying column is connected to the buffer tank through a feed pump, and the hydrogen fluoride is transported through a delivery pump.

[0021] A method for separating and purifying tail gas of a fluorinated phosphate system, comprising the following steps:

[0022] Step 1:

[0023] The tail gas is pressurized to 0.3-1.0 MPa by a compressor, and the pressurized tail gas is cooled to -20-45°C by a condenser.

[0024] Step 2:

[0025] The tail gas of Step 1 is passed through a buffer tank, and the buffer tank preferably has a wire mesh structure. When the pressurized and condensed tail gas passes through the buffer tank, the hydrogen fluoride and hydrogen chloride liquid droplets larger than 10 μm are separated from the uncondensed nitrogen.

[0026] Step 3:

[0027] The tail gas separated by the buffer tank, i.e. hydrogen fluoride, hydrogen chloride droplets and nitrogen smaller than 10 microns, is subjected to gas-liquid separation by a coalescer, the nitrogen recovered after separation by the coalescer is used, and the liquid recovered after separation by the coalescer is temporarily stored in the buffer tank;

[0028] Step four:

[0029] The liquid temporarily stored in the buffer tank in step three is delivered to the rectifying column by a feed pump for separation of hydrogen chloride and hydrogen fluoride, the hydrogen chloride discharged from the top of the column is subjected to water absorption to produce high-quality hydrochloric acid, and the hydrogen fluoride discharged from the bottom of the column is returned to the device for recycling.

[0030] Preferably, the control feed amount of the rectifying column in step four is 100-102 kg / h, the top pressure is 0.2-0.6 MPa, the top temperature is -40 to -50 DEG C, the output amount is 80-90 kg / h, the bottom temperature is -2 to -7 DEG C, and the output amount is 15.5-17.5 kg / h.

[0031] The application provides a fluorinated phosphate system tail gas separation and purification device.

[0032] The application has the following beneficial effects: BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The device diagram of the application.

[0034] 1, compressor; 2: condenser; 3: separation tank; 4: coalescer; 5: buffer tank; 6: feed pump; 7: rectifying column; 8: delivery pump. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0036] As one aspect of the application, please refer to the attached Figure 1 The embodiment of the application provides a fluorinated phosphate system tail gas separation and purification device, which comprises:

[0037] Compressor 1, compressor 1 is used to pressurize the tail gas, which uses an oil-free compressor.

[0038] Condenser 2, condenser 2 is used to cool the pressurized tail gas, and condense the hydrogen fluoride and hydrogen chloride in the tail gas to form droplets.

[0039] Separation tank 3, separation tank 3 is used to separate the droplets formed after condensation from nitrogen, and the inside uses demisting wire mesh to separate gas and liquid.

[0040] Coalescer 4, coalescer 4 is used to capture hydrogen fluoride and hydrogen chloride droplets smaller than 10 μm into large droplets after filtration and separation from nitrogen, and the separated liquid is recycled into buffer tank 5 for temporary storage, the coalescer is made of stainless steel, and the filter core is made of metal sintered filter screen.

[0041] Rectification column 7, rectification column 7 is used to purify the liquid temporarily stored in buffer tank 5, the number of trays of rectification column 7 is: 10-30, the reflux ratio is: 0.2-3, wherein hydrogen chloride is recovered from the top of the column, and hydrogen fluoride is recovered from the bottom of the column.

[0042] The rectification column 7 is connected with the buffer tank 5 through the feed pump 6, and the rectification column 7 transports the hydrogen fluoride through the delivery pump 8.

[0043] Example 1:

[0044] A 3000 tons / year fluorinated phosphate production device tail gas produces 680 tons of hydrogen chloride, 133 tons of hydrogen fluoride, and 2500 tons of nitrogen tail gas per year. The conventional method is to form 2720 tons of mixed acid hydrochloric acid 25%, hydrogen fluoride 5% by water absorption. Through the above-mentioned fluorinated phosphate system tail gas separation and purification device, the main steps are as follows:

[0045] Step one, the tail gas is pressurized to 0.7mpa by an oil-free compressor;

[0046] Step two, the pressurized tail gas is cooled to-30℃ by a condenser using chilled water, and the hydrogen fluoride and hydrogen chloride in the gas are condensed to form droplets. The gas-liquid mixture is separated by a separation tank with a demisting wire mesh, and liquid hydrogen chloride and hydrogen fluoride larger than 10 μm are captured and intercepted. The captured liquid hydrogen chloride and hydrogen fluoride enter the buffer tank with chilled water for temporary storage.

[0047] Step three, nitrogen and liquid droplets of hydrogen chloride and hydrogen fluoride smaller than 10 μm pass through a metal sintered mesh coalescer with a filtration precision of 1 μm. The coalescer captures small droplets into large droplets and separates them from nitrogen. The captured liquid and the liquid from step two are temporarily stored in the buffer tank with chilled water, and the purified nitrogen with a purity of 99.99% is returned to the device for use.

[0048] Step four, the liquid hydrogen chloride, hydrogen fluoride in the buffer tank is pumped into the rectification tower for purification. The rectification tower has 20 theoretical tower plates, the feeding amount is controlled at 101.6 kg / h, the tower top pressure is 0.4 MPa, the tower top temperature is -45℃, the output amount is 85 kg / h, the tower bottom temperature is -5℃, the output amount is 16.6 kg / h, the purity of the hydrogen chloride product at the tower top is 99.9999%, and the purity of the hydrogen chloride product at the tower bottom is 99.997%. The purified hydrogen fluoride is returned to the device for recycling, and the hydrogen chloride is made into high-quality hydrochloric acid by water absorption.

[0049] Example 2

[0050] A 3000 tons / year fluorinated phosphate production device produces 680 tons of hydrogen chloride, 133 tons of hydrogen fluoride and 2500 tons of nitrogen tail gas per year. After conventional water absorption, 2720 tons of mixed acid hydrochloric acid 25% and hydrogen fluoride 5% are formed. Through the above- provided fluorinated phosphate system tail gas separation and purification device, the main steps are as follows:

[0051] Step one, the tail gas is pressurized to 0.7 MPa by an oil-free compressor.

[0052] Step two, the pressurized tail gas is cooled to -30℃ by using chilled water through a condenser, and the gaseous hydrogen fluoride and hydrogen chloride are condensed into liquid droplets. The gas-liquid mixture is separated by a separation tank with a demisting screen to capture and intercept liquid hydrogen chloride and hydrogen fluoride larger than 10 μm. The captured liquid hydrogen chloride and hydrogen fluoride are temporarily stored in a buffer tank with chilled water cooling.

[0053] Step three, the nitrogen and liquid droplets smaller than 10 μm are collected by a metal sintered mesh coalescer with a filtration precision of 1 μm. The coalescer collects small droplets into large droplets and separates them from the nitrogen. The collected liquid is temporarily stored in the buffer tank with chilled water cooling together with the liquid in step two. The purified nitrogen with a purity of 99.99% is returned to the device for use.

[0054] Step four, the liquid hydrogen chloride and hydrogen fluoride in the buffer tank are pumped into the rectification tower for purification. The rectification tower has 20 theoretical tower plates, the feeding amount is controlled at 101.6 kg / h, the tower top pressure is 0.65 MPa, the tower top temperature is -30℃, the output amount is 83.66 kg / h, the tower bottom temperature is -5℃, the output amount is 17.94 kg / h, the purity of the hydrogen chloride product at the tower top is 99.9999%, and the purity of the hydrogen chloride product at the tower bottom is 92.54%. The purified hydrogen fluoride is returned to the phosphorus pentafluoride production device for recycling, and the hydrogen chloride is made into liquid hydrogen chloride for specific customer supply.

[0055] Example 3

[0056] A 3000 tons / year fluorinated phosphate production device tail gas produces 680 tons of hydrogen chloride, 133 tons of hydrogen fluoride, 2500 tons of nitrogen tail gas per year. The conventional method is to form 2720 tons of mixed acid hydrochloric acid 25%, hydrogen fluoride 5% after water absorption. Through the above- provided fluorinated phosphate system tail gas separation and purification device, the main steps are as follows:

[0057] Step one, the tail gas is pressurized to 0.6mpa by an oil-free compressor;

[0058] Step two, the pressurized tail gas is cooled to-42℃ by a condenser using chilled water, and the hydrogen fluoride and hydrogen chloride in the gas are condensed into liquid droplets. The gas-liquid mixture is separated by a separation tank with a demisting screen to capture and intercept liquid hydrogen chloride and hydrogen fluoride larger than 10μm. The captured liquid hydrogen chloride and hydrogen fluoride are temporarily stored in a buffer tank with-45℃ chilled water.

[0059] Step three, nitrogen and liquid droplets of hydrogen chloride and hydrogen fluoride smaller than 10μm are collected by a metal sintered screen coalescer with a filtration precision of 1μm. The coalescer collects small droplets into large droplets and separates them from nitrogen. The collected liquid is temporarily stored in a buffer tank with-45℃ chilled water together with the liquid from step two. The purified nitrogen with a purity of 99.99% is returned to the device for use.

[0060] Step four, the liquid hydrogen chloride and hydrogen fluoride in the buffer tank are pumped into a rectification column for purification. The rectification column has 25 theoretical tray numbers, the feed rate is 101.6kg / h, the column top pressure is 0.5mpa, the column top temperature is-35℃, the column top yield is 85kg / h, the column bottom temperature is-10℃, the column bottom yield is 16.6kg / h, the column top purified product hydrogen chloride purity is 99.9999%, and the column bottom purified product hydrogen fluoride purity is 99.99%. The purified hydrogen fluoride is returned to the phosphorus pentafluoride production device for recycling, and the hydrogen chloride is made into high-purity hydrochloric acid or high-purity liquid hydrogen chloride for specific customer supply.

[0061] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and changes can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A device for separating and purifying tail gas from a fluorinated phosphate system, characterized in that, include: Compressor (1), said compressor (1) is used to pressurize the exhaust gas to 0.3 to 1.0 MPa; Condenser (2), the condenser (2) is used to cool the pressurized tail gas and condense the hydrogen fluoride and hydrogen chloride in the tail gas into droplets; Separation tank (3), the separation tank (3) is used to separate the liquid droplets formed after condensation from nitrogen gas, and the gas-liquid separation is carried out inside by a demisting wire mesh; The coalescer (4) is used to capture hydrogen fluoride and hydrogen chloride droplets smaller than 10 μm into larger droplets, filter them, and separate them from nitrogen. The separated liquid is recycled into a buffer tank (5) for temporary storage. The coalescer (4) is made of stainless steel and its filter element is made of sintered metal mesh. The filtration accuracy is 0.8 to 1.2 μm. A distillation column (7) is used to purify the liquid temporarily stored in the buffer tank (5). The number of trays in the distillation column (7) is 10 to 30, and the reflux ratio is 0.2 to 3. Hydrogen chloride is recovered from the top of the column, and hydrogen fluoride is recovered from the bottom of the column.

2. The device for separating and purifying tail gas of a fluorinated phosphate system according to claim 1, characterized in that, The compressor (1) is an oil-free compressor, and the exhaust gas is pressurized to 0.5-0.8 MPa.

3. The device for separating and purifying tail gas of a fluorinated phosphate system according to claim 1, characterized in that, The distillation column (7) is connected to the buffer tank (5) via a feed pump (6), and the distillation column (7) is used to transport hydrogen fluoride via a transfer pump (8).

4. A method for separating and purifying tail gas from a fluorinated phosphate system, using a tail gas separation and purification device for a fluorinated phosphate system as described in any one of claims 1-3, characterized in that, Includes the following steps: Step 1: The exhaust gas is pressurized to 0.3-1.0 MPa by compressor (1), and the pressurized exhaust gas is cooled to -20℃--45℃ by condenser (2); Step Two: When the exhaust gas from step one is passed through the buffer tank (5), the pressurized and condensed exhaust gas is separated from the uncondensed nitrogen gas by liquefied hydrogen fluoride and hydrogen chloride droplets larger than 10μm passing through the buffer tank (5). Step 3: The tail gas separated by the buffer tank (5), namely hydrogen fluoride and hydrogen chloride droplets smaller than 10μm and nitrogen gas, are separated by the coalescer (4). The nitrogen gas separated by the coalescer (4) is recycled and reused. The liquid recovered by the coalescer (4) is temporarily stored in the buffer tank (5). Step Four: The liquid temporarily stored in the buffer tank (5) in step 3 is transported to the distillation column (7) by the feed pump (6) for the separation of hydrogen chloride and hydrogen fluoride. The hydrogen chloride is discharged through the top of the column and then absorbed by water to produce high-quality hydrochloric acid. The hydrogen fluoride is discharged through the bottom of the column and returned to the device for recycling.

5. The method for separating and purifying tail gas of a fluorinated phosphate system according to claim 4, characterized in that, In step four, the controlled feed rate of the distillation column (7) is 100-102 kg / h, the column top pressure is 0.2-0.6 MPa, the column top temperature is -40--50℃, the output rate is 80-90 kg / h, the column bottom temperature is -2--7℃, and the output rate is 15.5-17.5 kg / h.

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