A separation device for butane production

Abstract

The present invention belongs to the technical field of separation equipment, and mainly relates to a separation device for butane production, which includes an upper condenser and a lower condenser arranged in sequence from top to bottom. The tube side of the upper condenser is used to condense isobutane, and the tube side of the lower condenser is used to condense n-butane. The tube side of the lower condenser is used to communicate with a raw material tank, and the remaining raw material gas is discharged into the upper condenser. The upper condenser condenses to obtain a condensate containing n-butane and isobutane, and discharges it into the lower condenser. The lower condenser condenses the condensate so that the unevaporated part enters the raw material tank, and the evaporated part re-enters the upper condenser to condense to obtain isobutane. Through multiple cycles of condensation, n-butane and isobutane are respectively condensed at different condensation positions, solving the problem that the separation device cannot continuously separate n-butane and isobutane.

Description

Technical Field

[0001] The present invention belongs to the technical field of separation equipment, and mainly relates to a separation device for butane production. Background Art

[0002] In the petrochemical field, butane has isomers (both with the molecular formula C4H 10 ) which are n-butane and i-butane respectively, and are widely used in fuel, refrigerant and chemical raw material production due to their physical and chemical properties.

[0003] However, since the uses of n-butane and i-butane are not completely the same, after butane is prepared, a separation device is often used to separate n-butane and i-butane in butane for separate use.

[0004] In the patent application document with the authorization announcement number CN114307536A, a separation tower for n-butane and i-butane in n-butane isomerization is disclosed. The separation tower for n-butane and i-butane includes a separation tower shell fixedly connected to a separation tower base at the lower end, an air inlet pipe group fixedly connected to the lower end of the separation tower shell, and a separation mechanism connected to the inner top of the separation tower shell. The separation mechanism includes a main separation box and a pair of secondary separation boxes. A continuously replaceable separation belt is arranged between the main separation box and the secondary separation boxes. The continuously replaceable separation belt includes microporous molecular sieves. The microporous molecular sieves include multiple sections of molecular sieve units connected end to end. A wind power driving member is connected inside the air inlet pipe group, and a transmission component is connected between the wind power driving member and the continuously replaceable separation belt. Through the combined action of the wind power driving member, the transmission component and the continuously replaceable separation belt provided in the separation tower for n-butane and i-butane in n-butane isomerization, the continuous and stable separation effect of the continuously replaceable separation belt can be maintained.

[0005] However, the porosity of the microporous molecular sieve is relatively low, resulting in a limited adsorption capacity for n-butane or i-butane, and continuous separation operations cannot be carried out. The microporous molecular sieve needs to be regenerated or replaced frequently to meet the production requirements. Summary of the Invention

[0006] The present invention provides a separation device for butane production to solve the problem that the separation device in the prior art cannot continuously separate n-butane and i-butane.

[0007] To solve the above problems, the present invention adopts the following technical solutions:

[0008] A separation device for butane production, comprising an upper condenser and a lower condenser arranged in sequence from top to bottom. The shell side of the upper condenser is used to introduce a refrigerant at a first temperature, so that the tube side of the upper condenser can condense isobutane. The shell side of the lower condenser is used to introduce a refrigerant at a second temperature, so that the tube side of the lower condenser can condense n-butane. The tube side of the lower condenser is used to communicate with a raw material tank, so that the raw material tank discharges a raw material gas containing n-butane and isobutane downward to the lower condenser. The lower condenser condenses the raw material gas to obtain n-butane, and the remaining raw material gas is discharged into the upper condenser. The upper condenser condenses to obtain a condensate containing n-butane and isobutane, and discharges it into the lower condenser. The lower condenser condenses the condensate so that the unevaporated part enters the raw material tank, and the evaporated part re-enters the upper condenser to be condensed to obtain isobutane. The tube side of the upper condenser is communicated with the tube side of the lower condenser, so that the uncondensed raw material gas in the upper condenser circulates into the lower condenser to be re-condensed.

[0009] It has the following beneficial effects: The raw material gas is condensed four times. The first condensation obtains n-butane. The second condensation is the re-condensation of the uncondensed part of the first time, completing the recovery of the raw material gas. The third condensation is the purification of the liquid condensed in the second time, so that most of the liquid flowing back to the raw material tank is n-butane, which is convenient for condensing n-butane in the shell side of the lower condenser next time. The other part enters the upper condenser for the fourth condensation to obtain isobutane. The uncondensed part of the upper condenser re-enters the lower condenser for condensation through the gas circulation pipe. The condensed n-butane and isobutane can be discharged in time, thus solving the problem that the separation device cannot continuously separate n-butane and isobutane; at the same time, through multiple condensations, the purity of the condensed and collected n-butane and isobutane is higher.

[0010] Further, the upper condenser is provided with a first chamber and a second chamber respectively communicating with its tube side. The lower condenser is provided with a third chamber and a fourth chamber respectively communicating with its tube side. The third chamber is communicated with an inlet pipe, and the inlet pipe is communicated with the raw material tank, and a part of the inlet pipe extends into the interior of the third chamber. The fourth chamber is communicated with the raw material tank so that the unevaporated part enters the raw material tank. The third chamber is communicated with the first chamber through the tube side of the lower condenser, the first chamber is communicated with the fourth chamber through the tube side of the lower condenser, and the fourth chamber is communicated with the second chamber through the tube side of the lower condenser;

[0011] The n-butane condensed by the lower condenser drips into the third chamber to collect the n-butane in the third chamber;

[0012] The condensate obtained by condensation in the upper condenser drips into the first chamber, and then drips into the fourth chamber through the tube side of the lower condenser. The unevaporated part of the condensate enters the raw material tank, and the evaporated part of the condensate re-enters the upper condenser through the second chamber. The isobutane obtained by condensing the evaporated part in the upper condenser drips into the second chamber, and the isobutane in the second chamber is collected.

[0013] Further, a relay pipe is connected to the tube side of the lower condenser, and the first chamber is connected to the third chamber through the relay pipe;

[0014] Conical covers are provided at the tops of the inlet pipe and the relay pipe. There is a gap between the conical covers and the corresponding inlet pipe and relay pipe respectively, so that the raw material gas can enter the corresponding first chamber and third chamber from the corresponding inlet pipe and relay pipe, and the condensed liquid that drips can slide down along the top of the conical cover into the corresponding first chamber and third chamber.

[0015] It has the following beneficial effects: The conical cover can prevent the condensed liquid from dripping into the corresponding inlet pipe and relay pipe. In this way, the condensed liquid can accurately drip into the corresponding first chamber and third chamber, which is convenient for collection. At the same time, the raw material gas to be condensed can pass through the gap between the conical cover and the corresponding inlet pipe and relay pipe, without affecting the condensation of the raw material gas.

[0016] Further, a shunt pipe is connected to the tube side of the lower condenser. A part of the shunt pipe extends into the second chamber and is connected to it, so that the second chamber is connected to the fourth chamber through the shunt pipe.

[0017] It has the following beneficial effects: The shunt pipe can make the raw material gas condensed by the lower condenser enter the upper condenser for the condensation of isobutane.

[0018] Further, the first chamber is connected to a reflux chamber, and the reflux chamber is connected to the shunt pipe, so that the condensate in the first chamber can flow back into the lower condenser through the reflux chamber and the shunt pipe in sequence.

[0019] It has the following beneficial effects: The shunt pipe enables the condensate to re-enter the lower condenser for condensation.

[0020] Further, the third chamber is connected to a first collection chamber for storing the condensed n-butane, and the first collection chamber is connected to an n-butane discharge pipe to discharge the n-butane into the n-butane collection tank through the n-butane discharge pipe;

[0021] The second chamber is connected to a second collection chamber for storing the condensed isobutane, and the second collection chamber is connected to an isobutane discharge pipe to discharge the isobutane into the isobutane collection tank through the isobutane discharge pipe.

[0022] It has the following beneficial effects: The collection of n-butane and isobutane is realized through the first collection chamber and the second collection chamber respectively.

[0023] Furthermore, floating valve assemblies are elastically assembled in the up and down directions in the first chamber, the second chamber and the third chamber. The floating valve assembly includes a moving rod elastically assembled in the up and down directions and a floating body assembled on the moving rod.

[0024] Through holes are respectively provided at the bottoms of the first chamber, the second chamber and the third chamber. The corresponding through holes are respectively communicated with the reflux chamber, the first collection chamber and the second collection chamber. The corresponding moving rods are inserted into the corresponding through holes.

[0025] The condensed liquid makes the floating body float in the up and down directions to respectively control the closing between the first chamber and the reflux chamber, the second chamber and the second collection chamber, and the third chamber and the first collection chamber.

[0026] It has the following beneficial effects: The condensed liquid can make the moving rod move upward through the floating body, so as to realize the communication between the first chamber and the reflux chamber, the second chamber and the second collection chamber, and the third chamber and the first collection chamber, which is convenient for collecting the condensed liquid. When the condensed liquid is insufficient, under the action of the spring and its own gravity, the moving rod moves downward to block the through hole, preventing the raw material gas for condensation from entering the reflux chamber, the first collection chamber and the second collection chamber through the through hole.

[0027] Furthermore, a U-shaped tube is assembled in the fourth chamber. The two ends of the U-shaped tube are respectively communicated with the tube side of the lower condenser. Flow holes are provided on the U-shaped tube to enable the unevaporated part of the condensate to enter the fourth chamber through the flow holes.

[0028] Furthermore, a gas circulation pipe is communicated between the tube side of the upper condenser and the inlet pipe. A one-way valve is assembled in the gas circulation pipe to enable the raw material gas that has not been condensed in the upper condenser to circulate into the lower condenser for re-condensation.

[0029] It has the following beneficial effects: The one-way valve enables the uncondensed raw material gas to only move along the gas circulation pipe from the upper condenser to the lower condenser, but not vice versa.

[0030] Furthermore, an upper inlet pipe and an upper outlet pipe for the refrigerant of the first temperature to enter and exit are provided on the shell side of the upper condenser, and a lower inlet pipe and a lower outlet pipe for the refrigerant of the second temperature to enter and exit are provided on the shell side of the lower condenser.

[0031] A heat exchanger is communicated between the upper outlet pipe and the lower inlet pipe to enable the refrigerant of the first temperature to be converted into the refrigerant of the second temperature through the heat exchanger. Description of the Drawings

[0032] By reading the following detailed description with reference to the accompanying drawings, the above and other objects, features, and advantages of the exemplary embodiments of the present invention will become readily understandable. In the drawings, several embodiments of the present invention are shown in an exemplary rather than restrictive manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein:

[0033] Figure 1 is the front view of the present invention;

[0034] Figure 2 is the schematic structural view of the first perspective of the present invention after omitting the bracket;

[0035] Figure 3 is the schematic structural view of the second perspective of the present invention after omitting the bracket;

[0036] Figure 4 is Figure 3 the left view of;

[0037] Figure 5 is Figure 3 the right view of;

[0038] Figure 6 is the cross-sectional view of the first perspective of the present invention;

[0039] Figure 7 is the cross-sectional view of the second perspective of the present invention;

[0040] Figure 8 is the cross-sectional view of the third perspective of the present invention;

[0041] Figure 9 is the cross-sectional view of the fourth perspective of the present invention;

[0042] Figure 10 is the schematic structural view of the shunt tube;

[0043] Figure 11 is the schematic structural view of the U-shaped tube;

[0044] Figure 12 is the schematic structural view of the floating valve assembly.

[0045] Explanation of reference numerals:

[0046] 1. Support; 2. Upper inlet pipe; 3. Upper outlet pipe; 4. Lower inlet pipe; 5. Lower outlet pipe; 6. n-butane discharge pipe; 7. Return pipe; 8. isobutane discharge pipe; 9. Inlet pipe; 10. Upper condenser; 11. Lower condenser; 12. Gas circulation pipe; 13. Diverging pipe; 14. Third chamber; 15. First collection chamber; 16. Second collection chamber; 17. Relay pipe; 18. First chamber; 19. Second chamber; 20. Telescopic spring assembly; 21. Fourth chamber; 22. U-shaped pipe; 23. Upward floating valve assembly; 24. Return chamber; 25. First circulation chamber; 26. Second circulation chamber; 27. Conical cover; 28. Check valve; 29. Flow hole; 30. Moving rod; 31. Floating body. Detailed implementation mode

[0047] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Those skilled in the art should know that the embodiments described below are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present invention.

[0048] Next, various non-limiting implementation modes of the present invention will be specifically introduced. The number of any element in the accompanying drawings is used for illustration rather than limitation, and any naming is only used for distinction without any limiting meaning. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0049] As Figures 1-5 shown, a separation device for butane production, used to separate n-butane and isobutane. In this embodiment, the separation device includes a support 1, and an upper condenser 10 and a lower condenser 11 arranged on the support 1 in sequence from top to bottom. The shell side of the upper condenser 10 is used to introduce a refrigerant at a first temperature so that the tube side of the upper condenser 10 can condense isobutane, and the shell side of the lower condenser 11 is used to introduce a refrigerant at a second temperature so that the tube side of the lower condenser 11 can condense n-butane.

[0050] In this embodiment, the first temperature is -15°C and the second temperature is -5°C.

[0051] In other embodiments, the first temperature can be one of -13°C, or -14°C, or -16°C, or -17°C, or -18°C, etc., and the second temperature can be one of -2°C, or -3°C, or -4°C, or -6°C, or -7°C, or -8°C, or -9°C, etc.

[0052] In this embodiment, an upper inlet pipe 2 and an upper outlet pipe 3 for the refrigerant at the first temperature are provided on the shell side of the upper condenser 10. A lower inlet pipe 4 and a lower outlet pipe 5 for the refrigerant at the second temperature are provided on the shell side of the lower condenser 11. A heat exchanger is connected between the upper outlet pipe 3 and the lower inlet pipe 4 so that the refrigerant at the first temperature is converted into the refrigerant at the second temperature through the heat exchanger. The refrigerant first enters the shell side of the upper condenser 10 from the upper inlet pipe 2 at the first temperature, then exits from the upper outlet pipe 3, is converted into the second temperature through the heat exchanger, enters the shell side of the lower condenser 11 from the lower inlet pipe 4, and then exits from the lower outlet pipe 5.

[0053] In this embodiment, the refrigerant used in the upper condenser 10 and the lower condenser 11 is always the same one, only with different temperatures.

[0054] In other embodiments, two different refrigerants can also be used to enter the upper condenser 10 and the lower condenser 11 respectively, and the temperatures of these two refrigerants are different. At the same time, these two refrigerants do not need to exchange heat through the heat exchanger.

[0055] In this embodiment, as Figures 6-9 shown, a first chamber 18 and a second chamber 19 respectively communicating with the tube side are provided at the lower part of the upper condenser 10. The first chamber 18 is located in the middle, and the second chamber 19 is arranged around the first chamber 18. A third chamber 14 and a fourth chamber 21 respectively communicating with the tube side are provided at the lower part of the lower condenser 11. The third chamber 14 is located in the middle, and the fourth chamber 21 is arranged around the third chamber 14. An inlet pipe 9 is connected to the third chamber 14, and a part of the inlet pipe 9 extends into the third chamber 14. The inlet pipe 9 is connected to a raw material tank to discharge the raw material gas containing n-butane and isobutane into the tube side of the lower condenser 11 through the raw material tank. Part of the raw material gas is condensed in the tube side of the lower condenser 11 to obtain n-butane, and the n-butane drips into the third chamber 14. The remaining part of the raw material gas continues to flow upward to the tube side of the upper condenser 10.

[0056] An upper part of the tube side of the lower condenser 11 facing the third chamber 14 is connected to a relay pipe 17. The relay pipe 17 is connected to the first chamber 18, and a part of the relay pipe 17 extends into the first chamber 18. And the first chamber 18 is connected to the third chamber 14 through the relay pipe 17 and the tube side of the lower condenser 11 in sequence. The remaining part of the raw material gas is discharged into the upper condenser 10 through the relay pipe 17 and the first chamber 18 in sequence. The upper condenser 10 condenses to obtain a condensate containing n-butane and isobutane, and the condensate drips into the first chamber 18.

[0057] As Figure 9 、 Figure 10As shown in the figure, a shunt pipe 13 is connected to the upper part of the tube side of the lower condenser 11 facing the fourth chamber 21. The shunt pipe 13 is connected to the second chamber 19, and a part of the shunt pipe 13 extends into the second chamber 19, so that the second chamber 19 is connected to the fourth chamber 21 through the shunt pipe 13 and the tube side of the lower condenser 11 in sequence. The lower part of the first chamber 18 is connected to a reflux chamber 24, and the reflux chamber 24 is connected to the shunt pipe 13, so that the first chamber 18 is connected to the fourth chamber 21 through the reflux chamber 24 and the shunt pipe 13 in sequence. The condensate in the first chamber 18 can flow into the tube side of the lower condenser 11 through the reflux chamber 24 and the shunt pipe 13 in sequence. Due to the change in temperature, part of the condensate will evaporate in the tube side of the lower condenser 11. The unevaporated part of the condensate drips into the fourth chamber 21. The evaporated part of the condensate flows along the shunt pipe 13 into the second chamber 19, and finally enters the tube side of the upper condenser 10 for condensation, and the condensed isobutane drips into the second chamber 19.

[0058] In this embodiment, the position where the reflux chamber 24 is connected to the shunt pipe 13 is located outside the second chamber 19.

[0059] In this embodiment, as Figure 9 , Figure 11 shown, a U-shaped tube 22 is installed in the fourth chamber 21. The two ends of the U-shaped tube 22 are respectively connected to the tube side of the lower condenser 11 (facing the fourth chamber 21). A flow hole 29 is provided on the U-shaped tube 22, so that the unevaporated part of the condensate can enter the fourth chamber 21 through the flow hole 29. A reflux pipe 7 is connected to the fourth chamber 21, and the fourth chamber 21 is connected to the raw material tank through the reflux pipe 7, so that the unevaporated part of the above-mentioned condensate can flow back to the raw material tank.

[0060] In this embodiment, conical covers 27 are provided at the tops of the shunt pipe 13, the inlet pipe 9 and the relay pipe 17. There are intervals between the conical covers 27 and the corresponding shunt pipe 13, inlet pipe 9 and relay pipe 17 respectively, so that the raw material gas can enter the corresponding fourth chamber 21, first chamber 18 and third chamber 14 from the corresponding shunt pipe 13, inlet pipe 9 and relay pipe 17, and the dripped condensed liquid can slide down along the top of the conical cover 27 into the corresponding fourth chamber 21, first chamber 18 and third chamber 14, and will not drip into the shunt pipe 13, inlet pipe 9 and relay pipe 17. The conical cover 27 can prevent the condensed liquid from dripping into the corresponding shunt pipe 13, inlet pipe 9 and relay pipe 17. In this way, the condensed liquid can accurately drip into the corresponding fourth chamber 21, first chamber 18 and third chamber 14, which is convenient for collection. At the same time, the raw material gas to be condensed can pass through the interval between the conical cover 27 and the corresponding shunt pipe 13, inlet pipe 9 and relay pipe 17, without affecting the condensation of the raw material gas.

[0061] In this embodiment, the third chamber 14 is communicated with a first collection chamber 15 for containing condensed n-butane. The first collection chamber 15 is communicated with an n-butane discharge pipe 6. The n-butane in the third chamber 14 sequentially passes through the first collection chamber 15 and the n-butane discharge pipe 6, and thus is discharged into the corresponding n-butane collection tank. The second chamber 19 is communicated with a second collection chamber 16 for containing condensed isobutane. The second collection chamber 16 is communicated with an isobutane discharge pipe 8. The isobutane in the second chamber 19 sequentially passes through the second collection chamber 16 and the isobutane discharge pipe 8, and thus is discharged into the corresponding isobutane collection tank. In this way, the collection of n-butane and isobutane is respectively realized through the first collection chamber 15 and the second collection chamber 16.

[0062] In this embodiment, as Figure 9 , Figure 12 shown, in the first chamber 18, the second chamber 19 and the third chamber 14, a floating valve assembly 23 is elastically assembled in the vertical direction through a telescopic spring assembly 20. The floating valve assembly 23 includes a moving rod 30 elastically assembled in the vertical direction and a floating body 31 assembled on the moving rod 30. Through holes are respectively provided at the bottoms of the first chamber 18, the second chamber 19 and the third chamber 14. The corresponding through holes are respectively communicated with a reflux chamber 24, the first collection chamber 15 and the second collection chamber 16. The corresponding moving rods 30 are inserted into the corresponding through holes. The condensed liquid makes the floating body 31 float in the vertical direction. By controlling whether the moving rod 30 is inserted into the through hole, the communication between the corresponding first chamber 18 and the reflux chamber 24, between the second chamber 19 and the second collection chamber 16, and between the third chamber 14 and the first collection chamber 15 is respectively controlled. That is, the floating body 31 can float on the corresponding condensed liquid, and then drive the moving rod 30 to move upward. However, when the amount of the condensed liquid is not enough to make the floating body 31 float, the moving rod 30 moves downward and will block the above through hole.

[0063] The condensed liquid can make the moving rod 30 move upward through the floating body 31, so as to realize the communication between the first chamber 18 and the reflux chamber 24, between the second chamber 19 and the second collection chamber 16, and between the third chamber 14 and the first collection chamber 15, which is convenient for collecting the condensed liquid. When the condensed liquid is insufficient, under the action of the spring and its own gravity, the moving rod 30 moves downward to realize the blocking of the through hole and prevent the raw material gas for condensation from entering the reflux chamber 24, the first collection chamber 15 and the second collection chamber 16 through the through hole.

[0064] In this embodiment, as Figures 6-9As shown, the upper part of the tube side of the upper condenser 10 facing the first chamber 18 is communicated with a first circulation chamber 25, and the upper part of the tube side of the upper condenser 10 facing the second chamber 19 is communicated with a second circulation chamber 26. There are two gas circulation pipes 12, one of which is communicated between the first circulation chamber 25 and the inlet pipe 9, and the other gas circulation pipe 12 is communicated between the second circulation chamber 26 and the inlet pipe 9. Check valves 28 are provided in both of these two gas circulation pipes 12. Through the two gas circulation pipes 12, the uncondensed raw material gas in the upper condenser 10 is circulated into the lower condenser 11 for re-condensation. The check valve 28 enables the uncondensed raw material gas to only move downward from the upper condenser 10 to the lower condenser 11 along the gas circulation pipe 12, and not vice versa.

[0065] In other embodiments, only one gas circulation chamber is communicated with the upper part of the tube side of the upper condenser 10, and there is also only one gas circulation pipe 12, and this gas circulation pipe 12 is communicated between the gas circulation chamber and the inlet pipe 9. The gas circulation pipe 12 is provided with a check valve 28.

[0066] The raw material gas is condensed four times. Among them, n-butane is obtained in the first condensation, and the second condensation is the re-condensation of the uncondensed part in the first condensation, completing the recovery of the raw material gas. The third condensation is the purification of the liquid condensed in the second condensation, so that most of the n-butane flowing back to the raw material tank is n-butane, which is convenient for the next time to enter the shell side of the lower condenser 11 to condense out n-butane. The other part enters the upper condenser 10 for the fourth condensation to obtain isobutane. The uncondensed part in the upper condenser 10 re-enters the lower condenser 11 through the gas circulation pipe 12 for condensation, and the condensed n-butane and isobutane can be discharged in time, thus solving the problem that the separation device cannot continuously separate n-butane and isobutane; at the same time, through multiple condensations, the purity of the condensed and collected n-butane and isobutane is higher.

[0067] In this embodiment, the refrigerant used is propane. Propane has a relatively low boiling point, about -42.1 °C under normal pressure, which can provide a relatively low temperature environment and enable n-butane and isobutane to condense into liquids at appropriate temperatures, thus achieving separation. Propane has good refrigeration performance, and its chemical properties are relatively stable, with less corrosion to the equipment. At the same time, propane has good circulation performance in the refrigeration system, can effectively transfer heat, and improve the efficiency of condensation separation.

[0068] In other embodiments, the refrigerant used can also be ethylene, or liquid nitrogen.

[0069] Among them, the boiling point of ethylene is -103.7°C, and even lower temperatures can be achieved, making it suitable for occasions with higher requirements for condensation temperature. When separating n-butane and isobutane, ethylene can be used as a refrigerant to provide a low enough temperature for n-butane and isobutane to condense at different temperature stages respectively, achieving a more refined separation. However, the operating pressure of ethylene is relatively high, requiring higher pressure resistance for equipment.

[0070] The boiling point of liquid nitrogen is extremely low, at -195.8°C, which can provide an ultra-low temperature environment. In some special condensation separation processes, when rapid temperature reduction is required to achieve efficient separation of n-butane and isobutane, or when extremely high separation purity is required, liquid nitrogen can be used as a refrigerant. It can cause n-butane and isobutane to condense rapidly, and due to the slowdown of molecular motion at low temperatures, it is beneficial to improve the selectivity of separation. However, the cost of liquid nitrogen is relatively high, and special storage and supply equipment are required.

[0071] The working process of the present invention is as follows:

[0072] First, propane at -15°C is introduced into the shell side of the upper condenser 10. After the propane comes out of the upper condenser 10, it re-enters the shell side of the lower condenser 11 through the heat exchanger, and at this time the temperature of the propane is -5°C.

[0073] The raw material gas in the raw material tank is transported to the lower condenser 11 through the inlet pipe 9. The raw material gas is condensed in the tube side of the lower condenser 11 to obtain n-butane. The n-butane drips into the third chamber 14, and the corresponding floating valve assembly 23 floats, causing the n-butane to flow into the first collection chamber 15, and then is discharged to the corresponding n-butane collection tank through the n-butane discharge pipe 6.

[0074] The remaining uncondensed raw material gas enters the tube side of the upper condenser 10, and the upper condenser 10 will condense most of the remaining uncondensed raw material gas to obtain condensate, which will drip into the first chamber 18. Among them, another part of the remaining uncondensed raw material gas circulates back to the inlet pipe 9 through the corresponding gas circulation pipe 12 and waits to be condensed again.

[0075] The condensate in the first chamber 18 will flow into the tube side of the lower condenser 11 through the reflux chamber 24 and the shunt pipe 13 in sequence.

[0076] Due to temperature changes, the condensate will be divided into two parts, one part evaporates and the other part does not. The non-evaporated part of the condensate drips into the fourth chamber 21, and the non-evaporated part of these condensates will flow back into the raw material tank.

[0077] The evaporation part of the condensate flows along the shunt pipe 13 into the second chamber 19, and finally enters the tube side of the upper condenser 10 for condensation. Most of the evaporation part of the condensate is condensed to obtain isobutane. The isobutane drips into the second chamber 19, and the corresponding floating valve assembly 23 floats, enabling the isobutane to flow into the second collection chamber 16, and then being discharged into the corresponding isobutane collection tank through the isobutane discharge pipe 8.

[0078] Wherein, another part of the evaporation part of the condensate is recirculated through the corresponding gas circulation pipe 12 to the inlet pipe 9 for the next re-condensation.

Claims

1. A separation device for butane production, characterized in that: The invention comprises an upper condenser and a lower condenser which are arranged in sequence from top to bottom, wherein the shell side of the upper condenser is used to introduce a refrigerant of a first temperature so that the tube side of the upper condenser can condense isobutane, and the shell side of the lower condenser is used to introduce a refrigerant of a second temperature so that the tube side of the lower condenser can condense normal butane, and the tube side of the lower condenser is used to communicate with a raw material tank so that the raw material tank discharges raw material gas containing normal butane and isobutane toward the lower condenser, the lower condenser condenses the raw material gas to obtain normal butane, and the remaining raw material gas is discharged into the upper condenser, the upper condenser condenses to obtain a condensate containing normal butane and isobutane, and the condensate is discharged into the lower condenser, the lower condenser condenses the condensate so that the unevaporated part thereof enters the raw material tank, and the evaporated part re-enters the upper condenser so that it is condensed to obtain isobutane, and the tube side of the upper condenser is connected with the tube side of the lower condenser so that the uncondensed raw material gas of the upper condenser circulates into the lower condenser for re-condensation; The upper condenser is provided with a first cavity and a second cavity respectively connected to the tube paths thereof, and the lower condenser is provided with a third cavity and a fourth cavity respectively connected to the tube paths thereof, the third cavity is connected with an inlet pipe, the inlet pipe is connected to the raw material tank, and a part of the inlet pipe extends into the third cavity, the fourth cavity is connected to the raw material tank so that the unevaporated part thereof enters the raw material tank, the third cavity is connected to the first cavity through the tube path of the lower condenser, the first cavity is connected to the fourth cavity through the tube path of the lower condenser, and the fourth cavity is connected to the second cavity through the tube path of the lower condenser; The n-butane condensed by the lower condenser drips into the third chamber, and the n-butane in the third chamber is collected; The condensate obtained by condensation in the upper condenser drips into the first chamber, and then drips into the fourth chamber through the tube side of the lower condenser. The unevaporated part of the condensate enters the raw material tank, and the evaporated part of the condensate re-enters the upper condenser through the second chamber. The isobutane obtained by condensing the evaporated part of the upper condenser drips into the second chamber, and the isobutane in the second chamber is collected.

2. A separation device for butane production according to claim 1, characterized in that: The tube side of the lower condenser is connected with a relay pipe, and the first chamber is connected with the third chamber through the relay pipe; The tops of the inlet pipe and the relay pipe are each provided with a conical cover, and the conical cover is spaced apart from the corresponding inlet pipe and the relay pipe, so that the raw gas can enter the corresponding first cavity and the third cavity from the corresponding inlet pipe and the relay pipe, and the dripping condensed liquid can slide along the top of the conical cover into the corresponding first cavity and the third cavity.

3. A separation device for butane production according to claim 2, characterized in that: The tube side of the lower condenser is connected with a shunt pipe, a part of which extends into the second cavity and is connected with it, so that the second cavity is connected with the fourth cavity through the shunt pipe.

4. A separation device for butane production according to claim 3, characterized in that: The first cavity is connected with a reflux cavity, and the reflux cavity is connected with the diverter pipe, so that the condensate in the first cavity can flow back to the lower condenser through the reflux cavity and the diverter pipe in sequence.

5. A separation device for butane production according to claim 4, characterized in that: The third chamber is connected to a first collecting chamber for holding condensed n-butane, and the first collecting chamber is connected to a n-butane discharge pipe, so as to discharge the n-butane into the n-butane collection tank through the n-butane discharge pipe; The second chamber is connected to a second collecting chamber for holding condensed isobutane, and the second collecting chamber is connected to an isobutane discharge pipe to discharge the isobutane into the isobutane collection tank through the isobutane discharge pipe.

6. A separation device for butane production according to claim 5, characterized in that: The first chamber, the second chamber and the third chamber are all elastically equipped with a floating valve assembly in the up-down direction, and the floating valve assembly includes a moving rod elastically equipped in the up-down direction and a floating body equipped on the moving rod; The bottoms of the first cavity, the second cavity and the third cavity are respectively provided with through holes, and the corresponding through holes are respectively connected to the reflux cavity, the first collection cavity and the second collection cavity, and the corresponding moving rods are inserted into the corresponding through holes; The condensed liquid makes the float float in the up and down directions, so as to respectively control the closure between the first chamber and the reflux chamber, the second chamber and the second collecting chamber, and the third chamber and the first collecting chamber.

7. A separation device for butane production according to claim 6, characterized in that: The fourth cavity is equipped with a U-shaped tube, the two ends of which are respectively connected to the tube side of the lower condenser, and the U-shaped tube is provided with flow holes so that the unevaporated part of the condensate enters the fourth cavity through the flow holes.

8. A separation device for butane production according to any one of claims 1 to 7, characterized in that: A gas circulation pipe is connected between the pipe side of the upper condenser and the inlet pipe, and a one-way valve is installed in the gas circulation pipe to allow the uncondensed raw gas of the upper condenser to circulate into the lower condenser for re-condensation.

9. A separation device for butane production according to claim 8, characterized in that: The upper condenser is provided with an upper inlet pipe and an upper outlet pipe for the first temperature refrigerant to enter and exit the shell side, and the lower condenser is provided with a lower inlet pipe and a lower outlet pipe for the second temperature refrigerant to enter and exit the shell side; A heat exchanger is connected between the upper outlet pipe and the lower inlet pipe, so that the refrigerant at the first temperature is converted into the refrigerant at the second temperature through the heat exchanger.

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