Rectification device for single-tower side-draw high-purity anhydrous hydrogen fluoride

Abstract

The utility model discloses a rectification device for single-tower side-draw high-purity anhydrous hydrogen fluoride, which comprises a rectification tower, one side of the tower top of the rectification tower is communicated with a cold feeding pipeline, one side of the middle of the rectification tower is communicated with a hot feeding pipeline, the hot feeding pipeline is communicated with a preheater, and the upper part of the tower top of the rectification tower is communicated with a condenser I through a pipeline; one side, opposite to the hot feeding pipeline, of the middle of the rectifying tower is communicated with a condenser II through a pipeline. According to the utility model, through a feeding mode of cold and hot two streams of fluid, gas-phase hydrogen fluoride separated from hot feeding in the tower is condensed and pressed down through tower top cold feeding and is enriched in the middle of the tower body, and meanwhile, non-condensable gas is discharged from the tower top, so that the concentration ratio of the gas-phase hydrogen fluoride in the middle of the tower body is increased; therefore, high-purity anhydrous hydrogen fluoride can be laterally extracted from the middle part of the tower body, and the extraction of the high-purity anhydrous hydrogen fluoride product can be completed in the single-stage rectifying tower, so that the comprehensive cost and the safety risk are also reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of anhydrous hydrogen fluoride production equipment, and particularly relates to a distillation device for producing high-purity anhydrous hydrogen fluoride through a single-tower side line. Background Art

[0002] The production of anhydrous hydrogen fluoride in my country mainly adopts the fluorite-sulfuric acid method and the fluosilicic acid method. Due to the relatively rich reserves of fluorite resources in my country, the industrial production of anhydrous hydrogen fluoride is still mainly based on the fluorite-sulfuric acid method. The purification and separation of high-purity anhydrous hydrogen fluoride in the fluorite-sulfuric acid method has become the key factor for the success of this method. At present, most technologies in the production of anhydrous hydrogen fluoride use distillation to separate and purify anhydrous hydrogen fluoride. The main research is reflected in the process flow of obtaining high-purity anhydrous hydrogen fluoride by increasing the control point to stabilize the operation of the distillation tower and the two-stage distillation separation sequence of first removing heavy and then light, or first removing light and then heavy. The two-stage distillation has a higher purity of anhydrous hydrogen fluoride and is widely used. However, this technology also has shortcomings, mainly including:

[0003] (1) Two-stage distillation technology uses two-stage distillation towers, two-stage condensers, and two-stage reboilers, which requires a lot of equipment and high investment;

[0004] (2) The energy consumption of two-stage distillation technology is higher than that of single-stage distillation, and the operating cost of the technology is higher;

[0005] (3) The daily control of the two-stage distillation technology is relatively complicated, and the temperature of the tower fluctuates greatly, which can easily cause damage to the top condenser and unstable purity of the anhydrous hydrogen fluoride product;

[0006] (4) Anhydrous hydrogen fluoride is a highly dangerous process, and the increase in the number of equipment increases the safety risk of the device. Utility Model Content

[0007] The utility model aims to provide a distillation device for producing high-purity anhydrous hydrogen fluoride through a single-tower side line, thereby solving the problem of unstable purity of the existing anhydrous hydrogen fluoride product.

[0008] The technical solution adopted by the utility model is: a single-tower side-line distillation device for producing high-purity anhydrous hydrogen fluoride, comprising a distillation tower, a top side of the distillation tower being connected to a cold feed pipeline, a middle side of the distillation tower being connected to a hot feed pipeline, the hot feed pipeline being connected to a preheater, the top of the distillation tower being connected to a condenser I through a pipeline, and the middle side of the distillation tower opposite to the hot feed pipeline being connected to a condenser II through a pipeline.

[0009] The utility model is also characterized in that:

[0010] The top of the condenser I is connected to a non-condensable gas pipeline I, and the bottom of the condenser I is connected to the top of the distillation tower through a pipeline.

[0011] The top of the condenser II is connected with a non-condensable gas pipeline II, and the bottom of the condenser II is connected with an anhydrous hydrogen fluoride pipeline.

[0012] The distillation tower kettle is connected to a reboiler.

[0013] The bottom of the distillation tower is connected to a residual acid production pipeline, and the residual acid production pipeline is connected to a residual acid production pump.

[0014] The beneficial effects of the utility model are as follows: the distillation device for producing high-purity anhydrous hydrogen fluoride from a single tower side line of the utility model adopts a feeding method of two cold and hot fluids, wherein the cold feed at the top of the tower condenses and presses the gaseous hydrogen fluoride separated from the hot feed in the tower downward and enriches it in the middle of the tower body, and at the same time, non-condensable gas is discharged from the top of the tower, thereby increasing the concentration ratio of the gaseous hydrogen fluoride in the middle of the tower body, thereby making it possible to produce high-purity anhydrous hydrogen fluoride from the side line in the middle of the tower body, and because the production of the high-purity anhydrous hydrogen fluoride product can be completed in the single-stage distillation tower, the overall cost and safety risks are also reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic structural diagram of a single-tower distillation device for producing high-purity anhydrous hydrogen fluoride through a side line according to the present invention;

[0016] Figure 2 The utility model is a schematic diagram of the gas phase mass fraction on different plates of the distillation tower in the distillation device for producing high-purity anhydrous hydrogen fluoride through a single-tower side line.

[0017] In the figure, 1. distillation tower, 2. cold feed pipeline, 3. hot feed pipeline, 4. preheater, 5. condenser I, 6. condenser II, 7. non-condensable gas pipeline I, 8. non-condensable gas pipeline II, 9. anhydrous hydrogen fluoride pipeline, 10. reboiler, 11. residual acid production pipeline, 12. residual acid production pump. DETAILED DESCRIPTION

[0018] The present invention will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0019] The utility model provides a single-tower side-line distillation device for producing high-purity anhydrous hydrogen fluoride. Figure 1As shown, the distillation tower 1 comprises a cold feed pipeline 2 connected to the top of the distillation tower 1, a hot feed pipeline 3 connected to the middle of the distillation tower 1, and a preheater 4 connected to the hot feed pipeline 3. A condenser I5 is connected above the top of the distillation tower 1 via a pipeline. A non-condensable gas pipeline I7 is connected above the top of the condenser I5, and the bottom of the condenser I5 is connected to the top of the distillation tower 1 via a pipeline. A condenser II6 is connected to the middle of the distillation tower 1 on the side opposite the hot feed pipeline 3 via a pipeline. A non-condensable gas pipeline II8 is connected above the top of the condenser II6, and an anhydrous hydrogen fluoride pipeline 9 is connected to the bottom of the condenser II8. A reboiler 10 is connected to the bottom of the distillation tower 1. A residual acid extraction pipeline 11 is connected to the bottom of the distillation tower 1, and a residual acid extraction pump 12 is connected to the residual acid extraction pipeline 11.

[0020] The utility model provides a single-tower distillation device for producing high-purity anhydrous hydrogen fluoride through a side line. When working:

[0021] (1) The crude hydrofluoric acid solution produced by the front-end fluorite-sulfuric acid method is distilled and separated. The crude hydrofluoric acid solution is divided into two streams, cold and hot, and enters the distillation tower 1. The temperature of the cold fluid is the temperature of the hydrofluoric acid produced by condensation separation in general process technology, which is 5-15°C. The hot fluid is heated to 50-60°C by the hot feed preheater 4. The flow rate of the cold fluid and the flow rate of the hot fluid are controlled at 1:3-4. The cold fluid enters the uppermost part of the distillation tower 1 through the cold feed pipe 2 for spraying, and the hot fluid enters the middle part of the distillation tower 1 through the hot feed pipe 3.

[0022] (2) The distillation tower 1 is operated under positive pressure, with the top pressure controlled at 0.15-0.35 MPag, the top temperature at 40-60°C, and the bottom temperature at 70-110°C.

[0023] (3) Non-condensable gas is produced from the top of the distillation tower 1, the main components of which are silicon tetrafluoride (boiling point of about -86.15°C), sulfur dioxide (boiling point of about -10.15°C) and carbon dioxide gas (boiling point of about -78.45°C). Anhydrous hydrogen fluoride gas (boiling point of about 19.55°C) is produced from the side line in the middle of the tower, with a temperature between 50 and 70°C. The bottom of the tower is mainly residual acid (sulfuric acid boiling point of about 279.85°C), which is produced and recovered through the residual acid production pipeline 11 and the residual acid production pump 12.

[0024] (4) A condenser I5 is provided at the top of the distillation tower 1. The liquid condensed by the condenser I5 flows back to the top of the distillation tower 1, and the non-condensable gas that has not condensed is discharged through the non-condensable gas pipeline I7.

[0025] (5) A reboiler 10 is provided at the bottom of the distillation tower 1, and the outlet vaporization rate of the reboiler 10 is controlled between 0.2 and 0.3, and a heat medium with a temperature greater than 150° C. is used for heating.

[0026] (6) High-purity anhydrous hydrogen fluoride gas is extracted from the middle of the distillation tower 1 and then condensed to 10-15°C through the condenser II6. The uncondensed non-condensable gas is discharged through the non-condensable gas pipeline II8. The purity of the generated liquid anhydrous hydrogen fluoride can at least meet the first-class requirements of industrial anhydrous hydrogen fluoride in GB / T 7746-2023 under normal circumstances and is extracted through the anhydrous hydrogen fluoride pipeline 9.

[0027] Through the above method, the distillation device of the utility model for producing high-purity anhydrous hydrogen fluoride from a single tower side line is:

[0028] (1) Through the feeding method of hot and cold fluids, the cold feed at the top of the tower condenses the gaseous hydrogen fluoride separated from the hot feed in the tower and presses it down to enrich it in the middle of the tower body, such as Figure 2 As shown, the proportion of hydrogen fluoride gas concentration above the first tower plate is even lower than that of some non-condensable gases. This is because the temperature of the gaseous hydrogen fluoride separated from the hot feed naturally decreases after rising to the top of the tower, and then exchanges heat with the cold feed below its boiling point. The gaseous hydrogen fluoride condenses and falls. As the tower plate moves downward, the liquid hydrogen fluoride is reheated and restored to the gas phase and enriched in the middle of the tower body. In the above process, the non-condensable gases have low boiling points. After rising, they are not affected by the cold feed and are discharged from the top of the tower, thereby increasing the proportion of gaseous hydrogen fluoride concentration in the middle of the tower body. As a result, high-purity anhydrous hydrogen fluoride can be produced from the side line in the middle of the tower body.

[0029] (2) Since the extraction of high-purity anhydrous hydrogen fluoride product can be completed in a single-stage distillation tower, one tower equipment is reduced, and the required space size of the distillation tower kettle is smaller than that of the double-tower distillation, which reduces the equipment investment, simplifies the process flow, reduces the difficulty of operation, and reduces the entrainment loss of hydrogen fluoride gas at the top of the tower; compared with the two-stage reboiler of the two-stage distillation tower, the amount of heat medium required for the hot feed preheater 4 is smaller, which reduces the heat load of the preheater 4 and reduces the equipment investment, thereby reducing the overall cost and safety risks.

[0030] Example 1

[0031] Taking 4000kg / h crude hydrofluoric acid solution as an example for large-scale implementation, the specific implementation parameters are shown in Table 1 Example 1. The 5°C crude hydrofluoric acid liquid from the upstream is divided into two streams, cold and hot, and enters the distillation tower 1. The ratio of the cold fluid flow rate to the hot fluid flow rate is 0.54. The hot fluid is heated to 50°C by the preheater 4. The cold fluid enters the uppermost part of the distillation tower 1 for spraying, and the hot fluid enters the middle part of the distillation tower 1. The top pressure of the distillation tower 1 is controlled at 0.20MPag, the top temperature is 46°C, and the bottom temperature is 84°C. Non-condensable gas is produced from the top of the distillation tower 1, the main components of which are silicon tetrafluoride, sulfur dioxide and carbon dioxide gas. Anhydrous hydrogen fluoride gas is produced from the side line in the middle of the tower, with a temperature between 50 and 70°C. The bottom of the tower is mainly the remaining residual acid, which is produced and recovered by the residual acid production pump 12. Condenser I5 is installed at the top of distillation tower 1. The condensed liquid is refluxed to the top of distillation tower 1, while uncondensed non-condensable gases are discharged through non-condensable gas pipeline I7. A reboiler 10 is installed at the bottom of distillation tower 1. The outlet vaporization rate of reboiler 10 is 0.25, and it is heated by a heat medium greater than 100°C. High-purity anhydrous hydrogen fluoride gas is produced at a flow rate of 3800 kg / h in the middle of distillation tower 1. It is cooled to 10°C by condenser II6. Non-condensable gas pipeline II8 is installed at condenser II6. The resulting anhydrous hydrogen fluoride has a purity of 99.986%.

[0032] Example 2

[0033] Taking 6000kg / h crude hydrofluoric acid solution as an example, the specific implementation parameters are shown in Table 1 Example 2. The 10°C crude hydrofluoric acid liquid from the upstream is divided into two streams, cold and hot, and enters the distillation tower 1. The ratio of the cold fluid flow rate to the hot fluid flow rate is 0.43. The hot fluid is heated to 55°C by the preheater 4. The cold fluid enters the uppermost part of the distillation tower 1 for spraying, and the hot fluid enters the middle part of the distillation tower 1. The top pressure of the distillation tower 1 is controlled at 0.25MPag, the top temperature is 43°C, and the bottom temperature is 89°C. Non-condensable gas is produced from the top of the distillation tower 1, the main components of which are silicon tetrafluoride, sulfur dioxide and carbon dioxide gas. Anhydrous hydrogen fluoride gas is produced from the side line in the middle of the tower, with a temperature between 50 and 70°C. The bottom of the tower is mainly the remaining residual acid, which is produced and recovered by the residual acid production pump 12. Condenser I5 is installed at the top of distillation tower 1. The condensed liquid flows back to the top of distillation tower 1, while uncondensed non-condensable gases are discharged through non-condensable gas pipeline I7. A reboiler 10 is installed at the bottom of distillation tower 1. The outlet vaporization rate of reboiler 10 is 0.25, and it is heated by a heat medium greater than 100°C. High-purity anhydrous hydrogen fluoride gas is produced at a flow rate of 5800 kg / h in the middle of distillation tower 1. It is cooled to 10°C by condenser II6. Non-condensable gas pipeline II8 is installed at condenser II6. The resulting anhydrous hydrogen fluoride has a purity of 99.988%.

[0034] Example 3

[0035] Taking 8000kg / h crude hydrofluoric acid solution as an example, the specific implementation parameters are shown in Table 1 Example 3. The 9°C crude hydrofluoric acid liquid from the upstream is divided into two streams, cold and hot, and enters the distillation tower 1. The ratio of the cold fluid flow rate to the hot fluid flow rate is 0.67. The hot fluid is heated to 58°C by the preheater 4. The cold fluid enters the uppermost part of the distillation tower 1 for spraying, and the hot fluid enters the middle part of the distillation tower 1. The top pressure of the distillation tower 1 is controlled at 0.28MPag, the top temperature is 48°C, and the bottom temperature is 86°C. Non-condensable gas is produced from the top of the distillation tower 1, the main components of which are silicon tetrafluoride, sulfur dioxide and carbon dioxide gas. Anhydrous hydrogen fluoride gas is produced from the side line in the middle of the tower, with a temperature between 50 and 70°C. The bottom of the tower is mainly the remaining residual acid, which is produced and recovered by the residual acid production pump 12. Condenser I5 is installed at the top of distillation tower 1. The condensed liquid flows back to the top of distillation tower 1, while uncondensed non-condensable gases are discharged through non-condensable gas pipeline I7. A reboiler 10 is installed at the bottom of distillation tower 1. The outlet vaporization rate of reboiler 10 is 0.25, and it is heated by a heat medium greater than 100°C. High-purity anhydrous hydrogen fluoride gas is produced at a flow rate of 7600 kg / h in the middle of distillation tower 1. It is cooled to 10°C by condenser II6. Non-condensable gas pipeline II8 is installed at condenser II6. The resulting anhydrous hydrogen fluoride has a purity of 99.987%.

[0036] Example 4

[0037] Taking a 4000 kg / h crude hydrofluoric acid solution as an example, the specific implementation parameters are shown in Table 1, Example 4. 9°C crude hydrofluoric acid liquid from upstream enters distillation tower 1. The cold fluid flow rate to hot fluid flow rate ratio is 0, i.e., only hot feed is used, and no cold feed is introduced into the tower top. The hot fluid is heated to 55°C by preheater 4 before entering the middle portion of distillation tower 1. The top pressure of distillation tower 1 is controlled at 0.20 MPa, the top temperature is 47°C, and the bottom temperature is 84°C. Non-condensable gases, primarily silicon tetrafluoride, sulfur dioxide, and carbon dioxide, are produced from the top of distillation tower 1. Anhydrous hydrogen fluoride gas, with a temperature between 50°C and 70°C, is produced from a sideline in the middle of the tower. The bottom of the tower primarily contains residual acid, which is recovered by a residual acid extraction pump 12. A condenser I5 is located at the top of distillation tower 1. The condensed liquid flows back to the top of distillation tower 1, while uncondensed non-condensable gases are discharged through non-condensable gas pipeline I7. A kettle reboiler 10 is installed at the bottom of distillation tower 1. The outlet vaporization rate of reboiler 10 is 0.25, and heating is performed using a heat medium greater than 100°C. Anhydrous hydrogen fluoride gas is produced from the middle of distillation tower 1 and cooled to 10°C via condenser II 6. Condenser II 6 is equipped with a non-condensable gas pipeline II 8. The resulting anhydrous hydrogen fluoride has a purity of 99.642%, which does not meet the first-grade requirements for industrial anhydrous hydrogen fluoride specified in GB / T 7746-2023.

[0038] Table 1 Device parameters of Examples 1 to 4

[0039]

[0040] As can be seen from Table 1, the purity of the anhydrous hydrogen fluoride prepared by Examples 1 to 3 of the present invention can all meet the first-class requirements of industrial anhydrous hydrogen fluoride in GB / T 7746-2023. However, in Example 4, since only hot feed is used, the purity of the obtained industrial anhydrous hydrogen fluoride does not meet the first-class requirements.

Claims

1. A single-tower side-line distillation device for producing high-purity anhydrous hydrogen fluoride, characterized in that: The invention comprises a distillation tower (1), wherein the top side of the distillation tower (1) is connected to a cold feed pipe (2), the middle side of the distillation tower (1) is connected to a hot feed pipe (3), the hot feed pipe (3) is connected to a preheater (4), the top of the distillation tower (1) is connected to a condenser I (5) through a pipe, and the middle side of the distillation tower (1) relative to the hot feed pipe (3) is connected to a condenser II (6) through a pipe.

2. The single-tower side-line distillation device for producing high-purity anhydrous hydrogen fluoride according to claim 1, characterized in that: The top of the condenser I (5) is connected to a non-condensable gas pipeline I (7), and the bottom of the condenser I (5) is connected to the top of the distillation tower (1) through a pipeline.

3. The single-tower side-line distillation device for producing high-purity anhydrous hydrogen fluoride according to claim 1, characterized in that: The top of the condenser II (6) is connected to a non-condensable gas pipeline II (8), and the bottom of the condenser II (6) is connected to an anhydrous hydrogen fluoride pipeline (9).

4. The single-tower side-line distillation device for producing high-purity anhydrous hydrogen fluoride according to claim 1, characterized in that: The bottom of the distillation tower (1) is connected to a reboiler (10).

5. The single-tower side-line distillation device for producing high-purity anhydrous hydrogen fluoride according to claim 1, characterized in that: The bottom of the distillation tower (1) is connected to a residual acid extraction pipeline (11), and the residual acid extraction pipeline (11) is connected to a residual acid extraction pump (12).

Images