A C5 fraction refining system and a method for refining pentane foaming agent using the same.

Abstract

This invention belongs to the field of C5 fraction separation technology, and discloses a C5 fraction refining system and a method for refining pentane foaming agent using it. The C5 fraction refining system includes: a heavy-reduction thickening tower, a refining tower, a condensate tank, an azeotropic agent injection line, and a finished product collection pipeline. The C5 fraction refining system provided by this invention can remove most of the target impurities in the heavy-reduction thickening tower, effectively reducing the number of trays in the refining tower, lowering equipment investment costs, simplifying the structure, reducing the likelihood of internal blockage, and extending the equipment's operating cycle. The pentane foaming agent refining method provided by this invention can effectively improve the quality of the pentane foaming agent, increasing pentane purity from approximately 50% to over 70%, completely removing DMF, and reducing the content of chlorine elements such as ammonium chloride to less than 10 ppm, as low as below 5 ppm.

Description

Technical Field

[0001] This invention belongs to the field of C5 fraction separation technology, specifically relating to a C5 fraction refining system and a method for refining pentane foaming agent using the same system. Background Technology

[0002] C5 fraction is an important byproduct of the petroleum cracking industry for producing olefins. It mainly includes alkanes, alkenes, dienes, and cyclic hydrocarbons, and also contains small amounts of C4 and C6 components. The high-value-added components of C5 alkanes (C5 fraction) are mainly n-pentane, isopentane, and cyclopentane, which have a wide range of applications, including the production of polyurethane foaming agents, desorbents or extractants in molecular sieve dewaxing processes, anesthetics, catalysts in polyethylene production, and deasphalting solvents.

[0003] The cracked C5 fraction undergoes pre-removal of light and heavy components, thermal dimerization, and pre-removal of heavy components to remove some alkynes and dicyclopentadiene. Then, a DMF (dimethylformamide) extractive distillation method is used to obtain a high-purity pentane blowing agent. However, the extraction solvent DMF also exists in trace amounts in the pentane blowing agent during this process. The residual DMF is detrimental to the subsequent use of the blowing agent and affects its quality.

[0004] Furthermore, the heavy component concentrate obtained after pretreatment of C5 feedstock is fed into a thermal polymerization reactor for thermal dimerization, followed by multi-stage distillation to obtain isoprene. Pentane blowing agent is generated during the synthesis of isoprene resin. Since the synthesis of isoprene resin uses Lewis acids such as AlCl3 as catalysts, the resulting pentane blowing agent contains chlorine-containing components such as ammonium chloride. This component limits the application range of the pentane blowing agent and also reduces its quality.

[0005] Currently, the traditional method to improve the quality of pentane foaming agent is to use a plate distillation column for distillation purification. However, this method requires a large number of plates (generally, a conventional distillation column has 50-70 plates, while a single column in a dual-tower extractive distillation column has more than 90 plates), and has a large reflux ratio and high energy consumption. In addition, the precipitation of ammonium chloride crystals during the distillation process can cause blockage of internal components such as the plates, shortening the equipment operating cycle and resulting in high costs in terms of equipment investment, production input, and maintenance.

[0006] Therefore, there is an urgent need to provide a method to improve the quality of pentane foaming agents, which can reduce the residue of impurities such as solvents and ammonium chloride, improve the purity of pentane, and reduce production costs. Summary of the Invention

[0007] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a C5 fraction refining system and a method for refining pentane blowing agents using the same system. The C5 fraction refining system provided by the present invention is less prone to clogging of the internal components of the refining equipment, and can save steam consumption, significantly reducing production costs; the pentane blowing agent prepared using this system has low residual amounts of solvents, ammonium chloride, and other impurities, and high pentane purity.

[0008] This invention provides a C5 fraction refining system.

[0009] Specifically, a C5 fraction refining system includes:

[0010] The heavy weight removal and concentration tower, from bottom to top, includes a heating section, a packing section, and a condensation section;

[0011] A refining tower is connected to the condenser section of the de-weighting and concentration tower, and a condenser is connected to the top of the refining tower;

[0012] A condensate tank, connected to the condenser, is equipped with a separator for separating the azeotropic agent and the refined C5 fraction;

[0013] An azeotropic agent injection line is connected to the separator, and the azeotropic agent injection line is provided with an azeotropic agent replenishment port. The output end of the azeotropic agent injection line is connected to the purification column.

[0014] Finished product extraction pipeline.

[0015] The aforementioned C5 fraction refining system also includes a preheater connected to the packing section of the deweighting and thickening tower. The material enters the packing section after preheating.

[0016] In the above-mentioned C5 fraction refining system, the packing section includes 3 to 5 packing zones from bottom to top, and the material enters the packing section from the 1st to 2nd zone from bottom to top.

[0017] In the aforementioned C5 fraction refining system, a feed distributor is installed within the packing section, located above each section of the packing zone. After entering, the liquid material is dispersed into the packing zone via the feed distributor, and the dispersed material flows uniformly downwards from within the packing zone.

[0018] In the aforementioned C5 fraction refining system, the de-heavy concentration tower also includes a circulating water pipeline for regulating the temperature at the top of the de-heavy concentration tower.

[0019] In the above-mentioned C5 fraction refining system, the condenser section of the de-heavy concentration tower is a vertical tube condenser. The gas phase in the tower enters the tube side after passing through the packing section. A regulating valve is installed on the upper water side of the shell side to regulate the circulating water volume in the circulating water pipeline, thereby regulating the condensation volume and controlling the temperature at the top of the tower.

[0020] In the above-mentioned C5 fraction refining system, the heating section of the de-heavy concentration tower is also connected to a de-heavy concentrate pipeline for discharging the concentrate from the de-heavy concentration tower.

[0021] In the aforementioned C5 fraction refining system, the deweighted concentrate pipeline is connected to the preheater to recover the waste heat of the concentrate. The concentrate and the liquid material in the preheater exchange heat, achieving heat recovery and utilization, effectively saving steam consumption and significantly reducing production costs.

[0022] It is understood that the outlet of the concentrate in the de-heavy concentration tower is equipped with a backflow preventer, so that the concentrate will not flow back when it flows out through the de-heavy concentrate pipeline.

[0023] In the C5 fraction refining system described above, a concentrate pump is also provided on the deweighted concentrate pipeline to provide power for the waste heat recovery and discharge of the concentrate.

[0024] In the above-mentioned C5 fraction refining system, the refining tower 300 has 20 to 30 trays.

[0025] In the above-mentioned C5 fraction refining system, the refining column is a valve-type tray distillation column.

[0026] In the above-mentioned C5 fraction refining system, the bottom of the refining tower is connected to a bottom liquid pipeline, which is connected to the second to third section from top to bottom of the packing section of the de-heavy concentration tower.

[0027] In the aforementioned C5 fraction refining system, a bottom liquid pump is also installed on the bottom liquid pipeline to provide power for transporting the bottom liquid produced by the refining tower.

[0028] It is understood that the outlet of the refining tower is equipped with a backflow preventer, so that the liquid in the reactor will not flow back when it flows out through the reactor liquid pipeline.

[0029] In the aforementioned C5 fraction refining system, the condensate tank is further equipped with a vent line for periodically discharging non-condensable gases and condensate. Furthermore, the vent line is located at the top of the condensate tank.

[0030] In the above-mentioned C5 fraction refining system, the azeotropic agent injection line is also equipped with a circulating injection pump to provide power for the reuse of the azeotropic agent obtained by the separator.

[0031] The aforementioned C5 fraction refining system also includes a reflux line connected to the finished product collection pipeline, wherein the reflux line and the azeotropic agent injection line are connected in parallel and converge to the refining tower.

[0032] In the aforementioned C5 fraction refining system, a reflux pump and a reflux regulating valve are also provided on the reflux line.

[0033] In the above-mentioned C5 fraction refining system, the finished product collection pipeline is also equipped with a reflux pump and connected to a reflux line, which is connected in parallel with the azeotropic agent injection line to the refining tower.

[0034] In the above-mentioned C5 fraction refining system, a reflux regulating valve is also provided on the reflux line.

[0035] In the above-mentioned C5 fraction refining system, the bottom liquid pump and the concentrate pump are metering pumps, such as plunger (or diaphragm) metering pumps with variable frequency motors.

[0036] In the above-mentioned C5 fraction refining system, the bottom end of the packing section of the de-heavy concentration tower is connected to the heating section and is located vertically in the middle of the upper side of the heating section, forming an inverted T-shaped structure; the lower part of the heating section is provided with a transverse U-shaped tube bundle, and the upper part of the heating section is a space without packing. During use, the liquid level of the heating section is controlled at 40% to 80%, and the uppermost part of the transverse U-shaped tube bundle has a liquid level of less than 40%.

[0037] In the aforementioned C5 fraction refining system, the heavy weight removal and concentration tower is a packed tower, and the packing used in the packing section is stainless steel Pall rings. The packed tower offers advantages over plate towers in terms of production capacity and separation efficiency. Furthermore, the lower pressure drop within the tower helps reduce operating costs, achieving energy savings, and provides greater operational flexibility.

[0038] The present invention also provides a method for refining pentane foaming agent.

[0039] Specifically, a method for refining a pentane blowing agent includes the following steps:

[0040] Step 1: Add the crude pentane foaming agent from the first to second section from the bottom to the packed section of the de-heavy concentration tower for preliminary distillation;

[0041] Step 2: Add azeotropic agent from the azeotropic agent replenishment port of the azeotropic agent injection line. The vapor phase at the top of the deweighting and concentration tower enters the purification tower and undergoes distillation together with the added azeotropic agent.

[0042] Step 3: The vapor phase at the top of the refining tower is condensed by the condenser and collected in the condensate tank. At the same time, the flow rate of the product returning to the refining tower in the reflux line is adjusted according to the quality of the product in the condensate tank. The finished product is collected through the finished product collection pipeline to obtain the refined pentane foaming agent.

[0043] Step 4: The bottom liquid of the refining tower is transported through the bottom liquid pipeline to the second or third section from top to bottom of the packing section of the de-heavy concentration tower for secondary distillation.

[0044] In step one of some embodiments of the present invention, the crude pentane foaming agent is preheated by a preheater before being added to the packing section of the deweighting and concentration tower.

[0045] In step one of some embodiments of the present invention, the preliminary distillation process is as follows: the pressure of the bottom of the de-heavy concentration tower is controlled at 40 kPa to 55 kPa, the bottom temperature is controlled at 70°C to 95°C, and the top temperature is controlled at 50°C to 60°C.

[0046] In step one of some embodiments of the present invention, during the preliminary distillation process, the liquid phase of the crude pentane foaming agent flows to the bottom of the de-heavy concentration tower, and is gradually concentrated by heating in the heating section to obtain a concentrated liquid. The concentrated liquid is transported to the preheater through the de-heavy concentration liquid pipeline to recover heat, and then collected by the concentrated liquid pump.

[0047] In step two of some embodiments of the present invention, the distillation process is as follows: the top pressure of the refining column is controlled at 15 kPa to 40 kPa, the bottom temperature of the refining column is controlled at 50°C to 60°C, and the top temperature of the refining column is controlled at 38°C to 50°C.

[0048] In step two of some embodiments of the present invention, the azeotropic agent is deoxygenated hot water.

[0049] In step two of some embodiments of the present invention, the temperature of the added azeotropic agent is 60°C to 66°C, and the addition amount is 0.1 to 50 L / h.

[0050] In step three of some embodiments of the present invention, the azeotropic agent is condensed from the top of the purification column by a condenser, separated and collected in the separator of the condensate tank, and then returned to the purification column for recycling via the azeotropic agent injection line.

[0051] In step three of some embodiments of the present invention, the process of adjusting the flow rate of the product returning to the refining tower in the reflux line according to the quality of the product in the condensate tank is as follows: the liquid level in the condensate tank is controlled at 20% to 80%, and when the DMF content in the condensate tank is greater than 3ppm and the chlorine content such as ammonium chloride is greater than 10ppm, the flow rate of the product returning to the refining tower in the reflux line is increased.

[0052] In step three of some embodiments of the present invention, the liquid level in the refining tower is controlled at 20% to 80%, and the liquid level is smoothly controlled by the return regulating valve set at the outlet of the bottom liquid pump.

[0053] In some embodiments of the present invention, the circulating water temperature used in the deweighting and concentration tower and the refining tower is 28°C to 30°C.

[0054] More specifically, a method for refining a pentane blowing agent includes the following steps:

[0055] Step 1: The crude pentane foaming agent is preheated in a preheater, and then enters the packing section of the de-heavy concentration tower from the first or second section from the bottom for preliminary distillation; the switch of the circulating water pipeline 240 acting on the condenser is turned on to control the pressure of the bottom of the de-heavy concentration tower at 40 kPa to 55 kPa, the bottom temperature at 70°C to 95°C, and the top temperature at 50°C to 60°C; the liquid phase of the crude pentane foaming agent flows to the bottom of the de-heavy concentration tower, and is gradually concentrated by heating in the heating section to obtain a concentrated liquid. The concentrated liquid is transported to the preheater through the de-heavy concentrate pipeline to recover heat, and then collected by the concentrate pump;

[0056] Step 2: Add azeotropic agent through the azeotropic agent replenishment port of the azeotropic agent injection line. The vapor phase at the top of the deweighting and concentration tower enters the purification tower and undergoes rectification together with the added azeotropic agent. The purification tower has 20 to 30 trays. Control the top pressure of the purification tower at 15 kPa to 40 kPa, the bottom temperature of the purification tower at 50°C to 60°C, and the top temperature of the purification tower at 38°C to 50°C.

[0057] Step 3: The vapor phase at the top of the refining column is condensed by the condenser and collected in the condensate tank. At the same time, the flow rate of the product returning to the refining column in the reflux line is adjusted according to the quality of the product in the condensate tank. The finished product is collected through the finished product collection line to obtain the refined pentane foaming agent. The azeotropic agent is condensed from the top of the refining column by the condenser, separated and collected in the separator of the condensate tank, and then returned to the refining column for recycling through the azeotropic agent injection line.

[0058] Step 4: The bottom liquid of the refining tower is transported through the bottom liquid pipeline to the second or third section from top to bottom of the packing section of the de-heavy concentration tower for secondary distillation.

[0059] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0060] (1) The C5 fraction refining system provided by the present invention includes a de-heavy concentration tower, a refining tower, a condensate tank, an azeotropic agent injection line, etc. Through the design of the structure of each equipment and pipeline, as well as the layout of the connection relationship, most of the target impurities can be removed in the de-heavy concentration tower, effectively reducing the number of trays in the refining tower and reducing the equipment investment cost. Compared with the traditional method, the C5 fraction refining system has a simple structure, is not prone to blockage of the tower internals, and has a long equipment operation cycle.

[0061] (2) The purification method for pentane foaming agent provided by this invention involves heating and concentrating the crude pentane foaming agent at the bottom of a heavy-duty concentration tower, separating it through distillation in the middle section, and condensing it at the top to increase reflux within the tower, thereby removing impurities from the pentane foaming agent. Furthermore, the addition of an azeotropic agent to the purification tower enables azeotropic distillation of the azeotropic agent and the pentane foaming agent, effectively removing chlorine-containing elements such as ammonium chloride and DMF solvent, thus improving the quality of the pentane foaming agent. Simultaneously, the azeotropic agent eliminates the formation of ammonium chloride crystals, reducing the likelihood of blockage in the tower internals, effectively extending the equipment operating cycle, and significantly reducing production operating costs.

[0062] (3) The purification method of pentane foaming agent provided by the present invention is simple, easy to operate, and highly efficient. It can effectively improve the quality of pentane foaming agent, increase the purity of pentane from about 50% to more than 70%, completely remove DMF, and reduce the content of chlorine elements such as ammonium chloride to less than 10 ppm, down to less than 5 ppm. Attached Figure Description

[0063] Figure 1 This is a schematic diagram of the C5 fraction refining system provided in an embodiment of the present invention;

[0064] Explanation of icon numbers:

[0065] Preheater-100, De-heavy concentration tower-200, Heating section-210, Packing section-220, Condensation section-230, Circulating water pipeline-240, De-heavy concentrate pipeline-250, Concentrate pump-251, Refining tower-300, Condenser-310, Kettle liquid pipeline-320, Kettle liquid pump-330, Condensate tank-400, Separator-410, Vent pipeline-420, Azeotropic agent injection line-500, Azeotropic agent replenishment port-510, Circulating injection pump-520, Finished product collection pipeline-600, Reflux line-610, Reflux regulating valve-611, Reflux pump-620. Detailed Implementation

[0066] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0067] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0068] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0069] Reference Figure 1 This invention provides a C5 fraction refining system, comprising:

[0070] The heavy weight removal and concentration tower 200, from bottom to top, includes a heating section 210, a packing section 220 and a condensation section 230;

[0071] The refining column 300 is connected to the condenser section 230 of the de-weighting and concentration column 200, and the top of the refining column 300 is connected to a condenser 310.

[0072] A condensate tank 400 is connected to a condenser 310. A separator 410 is provided on the condensate tank 400 for separating the azeotropic agent and the refined C5 fraction.

[0073] An azeotropic agent injection line 500 is connected to a separator 410. An azeotropic agent replenishment port 510 is provided on the azeotropic agent injection line 500. The output end of the azeotropic agent injection line 500 is connected to the purification column 300.

[0074] The finished product extraction pipeline is 600.

[0075] Furthermore, the aforementioned C5 fraction refining system also includes a preheater 100, which is connected to the packing section 220. The material enters the packing section 220 after preheating.

[0076] Furthermore, the packing section 220 includes 3 to 5 packing zones from bottom to top, and the material enters the packing section 220 from the 1st to 2nd zone from bottom to top.

[0077] Furthermore, the de-heavy concentration tower 200 also includes a circulating water pipeline 240 for regulating the temperature at the top of the de-heavy concentration tower 200.

[0078] Furthermore, the condenser section 230 of the de-heavy concentration tower 200 is a vertical tube condenser. After passing through the packing section 220, the gas phase in the tower enters the tube side. A regulating valve is installed on the upper water side of the shell side to regulate the circulating water volume in the circulating water pipeline 240, thereby regulating the condensation volume and controlling the temperature at the top of the tower.

[0079] Furthermore, the heating section 210 of the de-heavy concentration tower 200 is also connected to the de-heavy concentrate pipeline 250 for discharging the concentrate in the de-heavy concentration tower 200.

[0080] Furthermore, the deweighted concentrate pipeline 250 is connected to the preheater 100 to recover the waste heat of the concentrate.

[0081] It is understandable that the outlet of the concentrate in the de-heavy concentration tower 200 is equipped with a backflow preventer, so that the concentrate will not flow back when it flows out through the de-heavy concentrate pipeline 250.

[0082] Furthermore, the deweighted concentrate pipeline 250 is also equipped with a concentrate pump 251 to provide power for the recovery and discharge of waste heat from the concentrate.

[0083] Furthermore, the number of trays in the refining tower 300 is 20 to 30.

[0084] Furthermore, the bottom of the refining tower 300 is connected to a bottom liquid pipeline 320, which is connected to the second to third section from top to bottom of the packing section 220 of the deweighting and concentration tower 200.

[0085] Furthermore, a bottom liquid pump 330 is also installed on the bottom liquid pipeline 320 to provide power for conveying the bottom liquid produced by the refining tower 300.

[0086] Understandably, the discharge port of the refining tower 300 is equipped with a backflow preventer, so that when the liquid flows out through the liquid pipeline 320, there will be no backflow.

[0087] Furthermore, the condensate tank 400 is also equipped with a vent line 420 for periodically discharging non-condensable gases and condensate. The vent line 420 is located at the top of the condensate tank 400.

[0088] Furthermore, the azeotropic agent injection line 500 is also equipped with a circulating injection pump 520 to provide power for the reuse of the azeotropic agent separated by the separator 410.

[0089] Furthermore, the finished product extraction pipeline 600 is equipped with a reflux pump 620 and connected to a reflux line 610. The reflux line 610 is connected in parallel with the azeotropic agent injection line 500 and flows to the refining tower 300. Even further, the reflux line 610 is equipped with a reflux regulating valve 611. When the internal DMF content is greater than 3 ppm and the chlorine content (such as ammonium chloride) is greater than 10 ppm, the reflux pump 620 and the reflux regulating valve 611 adjust the flow rate of the condensate tank 400 back to the refining tower 300 via the reflux line 610 to 1.05 to 1.5 times the original reflux flow rate, thereby ensuring that the refined pentane foaming agent meeting the requirements is continuously extracted from the finished product extraction pipeline 600.

[0090] Furthermore, the kettle liquid pump 330 and the concentrate pump 251 are metering pumps, such as plunger (or diaphragm) metering pumps with variable frequency motors.

[0091] Furthermore, the bottom end of the packing section 220 of the deweighting and concentration tower 200 is connected to the heating section 210 and is located at the vertical position of the upper middle part of the heating section 210, forming an inverted T-shaped structure; the lower part of the heating section 210 is provided with a transverse U-shaped tube bundle, and the upper part of the heating section 210 is a space without packing. When in use, the liquid level of the heating section 210 is controlled at 40% to 80%, and the uppermost part of the transverse U-shaped tube bundle is less than 40% liquid level.

[0092] Furthermore, the deweighting and concentration tower 200 is a packed tower, and the packing material used in the packing section 220 is stainless steel Pall rings.

[0093] Furthermore, the refining column 300 is a floating valve tray distillation column.

[0094] This invention also provides a method for refining pentane foaming agent, which utilizes the C5 fraction refining system provided in the above embodiments, as detailed in Examples 1-5.

[0095] Implementation Case 1

[0096] A method for refining a pentane blowing agent, specifically including the following steps:

[0097] Step 1: The crude pentane foaming agent at room temperature is preheated by the preheater 100, and then enters the packing section 220 of the de-weighting concentration tower 200 (which includes three packing sections from bottom to top) from the first section from bottom to top for preliminary distillation; the switch of the circulating water pipeline 240 acting on the condenser 230 is turned on to control the pressure of the bottom of the de-weighting concentration tower 200 at 50 kPa, the bottom temperature at 90°C, and the top temperature at 55°C; the liquid phase of the crude pentane foaming agent flows to the bottom of the de-weighting concentration tower 200, and is gradually concentrated by heating in the heating section 210 (heating steam at 400 kg / h) to obtain a concentrated liquid. The liquid level in the bottom of the de-weighting concentration tower 200 is controlled at 45%. The concentrated liquid is transported to the preheater 100 through the de-weighting concentrate pipeline 250 to recover heat, and then collected by the concentrate pump 251;

[0098] Step 2: Add azeotropic deoxygenated hot water (65℃) to the azeotropic agent supply port 510 of the azeotropic agent injection line 500. The azeotropic agent flow rate is controlled at 10L / h. The vapor phase from the top of the heavy phase concentrator 200 enters the refining column 300 and undergoes rectification together with the added azeotropic agent. The refining column 300 has 20 trays. The bottom pressure of the refining column 300 is controlled at 50KPa, the top pressure at 35KPa, the bottom temperature at 55℃, and the top temperature at 46℃. The reflux flow rate is 1.0m³. 3 / h;

[0099] Step 3: The vapor phase at the top of the refining tower 300 is condensed by condenser 310 and collected in condensate tank 400. The liquid level in condensate tank 400 is controlled at 78%. When the DMF content in condensate tank 400 is greater than 3 ppm and the chlorine content (such as ammonium chloride) is greater than 10 ppm, the flow rate of reflux from reflux line 610 back to refining tower 300 is adjusted to 1.25 times the original reflux flow rate. This allows for continuous extraction of refined pentane foaming agent from the finished product outlet pipeline 600. The azeotropic agent, after being condensed by condenser 310 at the top of refining tower 300, is separated and collected in separator 410 of condensate tank 400. The liquid level in separator 410 is controlled at 60%, and the agent is returned to refining tower 300 via azeotropic agent injection line 500 for recycling. An azeotropic agent replenishment port 510 is installed on azeotropic agent injection line 500 to achieve stable control of the liquid level in separator 410.

[0100] Step 4: The bottom liquid of the refining tower 300 is transported through the bottom liquid pipeline 320 to the second section from top to bottom of the packing section 220 of the de-weighting and concentration tower 200 for secondary distillation. The bottom liquid in the refining tower 300 is controlled at 60%.

[0101] Under stable operation of the instruments and equipment in the de-concentration tower 200 and the purification tower 300 of this purification method, the crude pentane foaming agent fed to the de-concentration tower 200 contains approximately 52% pentane, 25 ppm DMF, and 360 ppm ammonium chloride and other chlorine elements. Sampling analysis from the pipeline taken from the condensate tank 400 at 1h, 2h, 4h, 6h, and 8h showed the following purity, DMF content, and ammonium chloride and other chlorine element content of the pentane foaming agent: (72.3121%, 0 ppm, 4.37 ppm); (71.5546%, 0 ppm, 4.38 ppm); (72.2211%, 0 ppm, 3.84 ppm); (72.8225%, 0 ppm, 4.33 ppm); (73.6763%, 0 ppm, 3.53 ppm). The quality of the pentane foaming agent has been steadily improved.

[0102] Implementation Case 2

[0103] A method for refining a pentane blowing agent, specifically including the following steps:

[0104] Step 1: The crude pentane foaming agent at room temperature is preheated by the preheater 100, and then enters the packing section 220 of the de-weighting concentration tower 200 (the packing section 220 includes 3 packing zones from bottom to top) from the first section from bottom to top for preliminary distillation; the switch of the circulating water pipeline 240 acting on the condenser 230 is turned on to control the pressure of the bottom of the de-weighting concentration tower 200 at 50 kPa, the bottom temperature at 90°C, and the top temperature at 55°C; the liquid phase of the crude pentane foaming agent flows to the bottom of the de-weighting concentration tower 200, and is gradually concentrated by heating in the heating section 210 (heating steam at 450 kg / h) to obtain a concentrated liquid. The liquid level in the bottom of the de-weighting concentration tower 200 is controlled at 45%. The concentrated liquid is transported to the preheater 100 through the de-weighting concentrate pipeline 250 to recover heat, and then collected by the concentrate pump 251;

[0105] Step 2: Add azeotropic deoxygenated hot water (65℃) to the azeotropic agent supply port 510 of the azeotropic agent injection line 500. The azeotropic agent flow rate is controlled at 30L / h. The vapor phase from the top of the heavy phase concentrator 200 enters the refining column 300 and undergoes rectification together with the added azeotropic agent. The refining column 300 has 20 trays. The reboiler pressure of the refining column 300 is controlled at 48KPa, the top pressure at 35KPa, the reboiler temperature at 55℃, the top temperature at 46℃, and the reflux flow rate is 0.9m³. 3 / h;

[0106] Step 3: The vapor phase at the top of the refining tower 300 is condensed by condenser 310 and collected in condensate tank 400. The liquid level in condensate tank 400 is controlled at 78%. When the DMF content in condensate tank 400 is greater than 3 ppm and the chlorine content (such as ammonium chloride) is greater than 10 ppm, the flow rate of reflux from reflux line 610 back to refining tower 300 is adjusted to 1.25 times the original reflux flow rate. This allows for continuous extraction of refined pentane foaming agent from the finished product outlet pipeline 600. The azeotropic agent, after being condensed by condenser 310 at the top of refining tower 300, is separated and collected in separator 410 of condensate tank 400. The liquid level in separator 410 is controlled at 60%, and the agent is returned to refining tower 300 via azeotropic agent injection line 500 for recycling. An azeotropic agent replenishment port 510 is installed on azeotropic agent injection line 500 to achieve stable control of the liquid level in separator 410.

[0107] Step 4: The bottom liquid of the refining tower 300 is transported through the bottom liquid pipeline 320 to the second section from top to bottom of the packing section 220 of the de-weighting and concentration tower 200 for secondary distillation. The bottom liquid in the refining tower 300 is controlled at 60%.

[0108] Under stable operation of the instruments and equipment in the de-concentration tower 200 and the purification tower 300 of this refining method, the crude pentane foaming agent fed to the de-concentration tower 200 contains approximately 52% pentane, 25 ppm DMF, and 360 ppm ammonium chloride and other chlorine elements. Analysis of samples taken from the condensate tank 400 pipeline at 1h, 2h, 4h, 6h, and 8h showed the following purity, DMF content, and ammonium chloride and other chlorine element content of the pentane foaming agent: (71.6135%, 0 ppm, 5.12 ppm); (71.2982%, 0 ppm, 4.95 ppm); (72.0013%, 0 ppm, 4.67 ppm); (72.1322%, 0 ppm, 4.29 ppm); (72.1276%, 0 ppm, 3.99 ppm). The quality of the pentane foaming agent has been steadily improved.

[0109] Implementation Case 3

[0110] A method for refining a pentane blowing agent, specifically including the following steps:

[0111] Step 1: The crude pentane foaming agent at room temperature is preheated by the preheater 100, and then enters the packing section 220 of the de-weighting concentration tower 200 (the packing section 220 includes 3 packing zones from bottom to top) from the first section from bottom to top for preliminary distillation; the switch of the circulating water pipeline 240 acting on the condenser 230 is turned on to control the pressure of the bottom of the de-weighting concentration tower 200 at 52 kPa, the bottom temperature at 92°C, and the top temperature at 56°C; the liquid phase of the crude pentane foaming agent flows to the bottom of the de-weighting concentration tower 200, and is gradually concentrated by heating in the heating section 210 (heating steam at 550 kg / h) to obtain a concentrated liquid. The liquid level in the bottom of the de-weighting concentration tower 200 is controlled at 45%. The concentrated liquid is transported to the preheater 100 through the de-weighting concentrate pipeline 250 to recover heat, and then collected by the concentrate pump 251;

[0112] Step 2: Add azeotropic deoxygenated hot water (65℃) to the azeotropic agent supply port 510 of the azeotropic agent injection line 500. The azeotropic agent flow rate is controlled at 40L / h. The vapor phase from the top of the heavy phase concentrator 200 enters the refining column 300 and undergoes rectification together with the added azeotropic agent. The refining column 300 has 20 trays. The bottom pressure of the refining column 300 is controlled at 52KPa, the top pressure at 35KPa, the bottom temperature at 56℃, and the top temperature at 46℃. The reflux flow rate is 1.5m³. 3 / h;

[0113] Step 3: The vapor phase at the top of the refining tower 300 is condensed by condenser 310 and collected in condensate tank 400. The liquid level in condensate tank 400 is controlled at 78%. When the DMF content in condensate tank 400 is greater than 3 ppm and the chlorine content (such as ammonium chloride) is greater than 10 ppm, the flow rate of reflux from reflux line 610 back to refining tower 300 is adjusted to 1.25 times the original reflux flow rate. This allows for continuous extraction of refined pentane foaming agent from the finished product outlet pipeline 600. The azeotropic agent, after being condensed by condenser 310 at the top of refining tower 300, is separated and collected in separator 410 of condensate tank 400. The liquid level in separator 410 is controlled at 60%, and the agent is returned to refining tower 300 via azeotropic agent injection line 500 for recycling. An azeotropic agent replenishment port 510 is installed on azeotropic agent injection line 500 to achieve stable control of the liquid level in separator 410.

[0114] Step 4: The bottom liquid of the refining tower 300 is transported through the bottom liquid pipeline 320 to the second section from top to bottom of the packing section 220 of the de-weighting and concentration tower 200 for secondary distillation. The bottom liquid in the refining tower 300 is controlled at 60%.

[0115] Under stable operation of the instruments and equipment in the de-concentration tower 200 and the purification tower 300 of this purification method, the crude pentane foaming agent fed to the de-concentration tower 200 contains approximately 52% pentane, 25 ppm DMF, and 360 ppm ammonium chloride and other chlorine elements. Sampling analysis from the pipeline taken from the condensate tank 400 at 1h, 2h, 4h, 6h, and 8h showed the following purity, DMF content, and ammonium chloride and other chlorine element content of the pentane foaming agent: (73.9981%, 0 ppm, 3.47 ppm); (73.7685%, 0 ppm, 3.82 ppm); (73.7351%, 0 ppm, 3.55 ppm); (73.1998%, 0 ppm, 4.12 ppm); (73.9898%, 0 ppm, 3.34 ppm). The quality of the pentane foaming agent has been steadily improved.

[0116] Implementation Case 4

[0117] A method for refining a pentane blowing agent, specifically including the following steps:

[0118] Step 1: The crude pentane foaming agent at room temperature is preheated by the preheater 100, and then enters the packing section 220 of the de-weighting concentration tower 200 (which includes 5 packing sections from bottom to top) from the second section from the bottom for preliminary distillation; the switch of the circulating water pipeline 240 acting on the condenser 230 is turned on to control the pressure of the bottom of the de-weighting concentration tower 200 at 53 kPa, the bottom temperature at 91°C, and the top temperature at 55°C; the liquid phase of the crude pentane foaming agent flows to the bottom of the de-weighting concentration tower 200, and is gradually concentrated by heating in the heating section 210 (heating steam at 500 kg / h) to obtain a concentrated liquid. The liquid level in the bottom of the de-weighting concentration tower 200 is controlled at 45%. The concentrated liquid is transported to the preheater 100 through the de-weighting concentrate pipeline 250 to recover heat, and then collected by the concentrate pump 251;

[0119] Step 2: Add azeotropic deoxygenated hot water (65℃) to the azeotropic agent supply port 510 of the azeotropic agent injection line 500. The azeotropic agent flow rate is controlled at 20L / h. The vapor phase from the top of the heavy phase concentrator 200 enters the refining column 300 and undergoes rectification together with the added azeotropic agent. The refining column 300 has 20 trays. The reboiler pressure of the refining column 300 is controlled at 51KPa, the top pressure at 35KPa, the reboiler temperature at 55℃, the top temperature at 46℃, and the reflux flow rate is 1.0m³. 3 / h;

[0120] Step 3: The vapor phase at the top of the refining tower 300 is condensed by condenser 310 and collected in condensate tank 400. The liquid level in condensate tank 400 is controlled at 78%. When the DMF content in condensate tank 400 is greater than 3 ppm and the chlorine content (such as ammonium chloride) is greater than 10 ppm, the flow rate of reflux from reflux line 610 back to refining tower 300 is adjusted to 1.15 times the original reflux flow rate. This allows for continuous extraction of refined pentane foaming agent from the finished product outlet pipeline 600. The azeotropic agent, after being condensed by condenser 310 at the top of refining tower 300, is separated and collected in separator 410 of condensate tank 400. The liquid level in separator 410 is controlled at 60%, and the agent is returned to refining tower 300 via azeotropic agent injection line 500 for recycling. An azeotropic agent replenishment port 510 is installed on azeotropic agent injection line 500 to achieve stable control of the liquid level in separator 410.

[0121] Step 4: The bottom liquid of the refining tower 300 is transported through the bottom liquid pipeline 320 to the third section from top to bottom of the packing section 220 of the de-heavy concentration tower 200 for secondary distillation. The bottom liquid in the refining tower 300 is controlled at 60%.

[0122] Under stable operation of the instruments and equipment in the de-concentration tower 200 and the purification tower 300 of this purification method, the crude pentane foaming agent fed to the de-concentration tower 200 contains approximately 52% pentane, 25 ppm DMF, and 360 ppm ammonium chloride and other chlorine elements. Sampling analysis from the pipeline taken from the condensate tank 400 at 1h, 2h, 4h, 6h, and 8h showed the following purity, DMF content, and ammonium chloride and other chlorine element content of the pentane foaming agent: (73.4543%, 0 ppm, 4.98 ppm); (72.9676%, 0 ppm, 4.67 ppm); (73.2315%, 0 ppm, 4.53 ppm); (73.4214%, 0 ppm, 4.77 ppm); (72.9713%, 0 ppm, 3.87 ppm). The quality of the pentane foaming agent has been steadily improved.

[0123] Implementation Case 5

[0124] A method for refining a pentane blowing agent, specifically including the following steps:

[0125] Step 1: The crude pentane foaming agent at room temperature is preheated by the preheater 100, and then enters the packing section 220 of the de-weighting concentration tower 200 (which includes 5 packing sections from bottom to top) from the second section from the bottom up for preliminary distillation; the switch of the circulating water pipeline 240 acting on the condenser section 230 is turned on to control the pressure of the bottom of the de-weighting concentration tower 200 at 54 kPa, the bottom temperature at 92°C, and the top temperature at 55°C; the liquid phase of the crude pentane foaming agent flows to the bottom of the de-weighting concentration tower 200, and is gradually concentrated by heating in the heating section 210 (heating steam at 550 kg / h) to obtain a concentrated liquid. The liquid level in the bottom of the de-weighting concentration tower 200 is controlled at 45%. The concentrated liquid is transported to the preheater 100 through the de-weighting concentrate pipeline 250 to recover heat, and then collected by the concentrate pump 251;

[0126] Step 2: Add azeotropic deoxygenated hot water (65℃) to the azeotropic agent supply port 510 of the azeotropic agent injection line 500. The azeotropic agent flow rate is controlled at 20L / h. The vapor phase from the top of the heavy phase concentrator 200 enters the refining column 300 and undergoes rectification together with the added azeotropic agent. The refining column 300 has 30 trays. The bottom pressure of the refining column 300 is controlled at 54KPa, the top pressure at 35KPa, the bottom temperature at 55℃, and the top temperature at 46℃. The reflux flow rate is 1.0m³. 3 / h;

[0127] Step 3: The vapor phase at the top of the refining tower 300 is condensed by condenser 310 and collected in condensate tank 400. The liquid level in condensate tank 400 is controlled at 78%. When the DMF content in condensate tank 400 is greater than 3 ppm and the chlorine content (such as ammonium chloride) is greater than 10 ppm, the flow rate of reflux from reflux line 610 back to refining tower 300 is adjusted to 1.15 times the original reflux flow rate. This allows for continuous extraction of refined pentane foaming agent from the finished product outlet pipeline 600. The azeotropic agent, after being condensed by condenser 310 at the top of refining tower 300, is separated and collected in separator 410 of condensate tank 400. The liquid level in separator 410 is controlled at 60%, and the agent is returned to refining tower 300 via azeotropic agent injection line 500 for recycling. An azeotropic agent replenishment port 510 is installed on azeotropic agent injection line 500 to achieve stable control of the liquid level in separator 410.

[0128] Step 4: The bottom liquid of the refining tower 300 is transported through the bottom liquid pipeline 320 to the third section from top to bottom of the packing section 220 of the de-heavy concentration tower 200 for secondary distillation. The bottom liquid in the refining tower 300 is controlled at 60%.

[0129] Under stable operation of the instruments and equipment in the de-concentration tower 200 and the purification tower 300 of this refining method, the crude pentane foaming agent fed to the de-concentration tower 200 contains approximately 52% pentane, 25 ppm DMF, and 360 ppm ammonium chloride and other chlorine elements. Sampling analysis from the pipeline taken from the condensate tank 400 at 1h, 2h, 4h, 6h, and 8h showed the following purity, DMF content, and ammonium chloride and other chlorine element content of the pentane foaming agent: (73.9889%, 0 ppm, 3.76 ppm); (73.4978%, 0 ppm, 3.81 ppm); (73.5355%, 0 ppm, 4.24 ppm); (73.1254%, 0 ppm, 4.12 ppm); (73.1098%, 0 ppm, 3.66 ppm). The quality of the pentane foaming agent has been steadily improved.

[0130] Comparison Case 1

[0131] A method for refining a pentane blowing agent, specifically including the following steps:

[0132] Step 1: The crude pentane foaming agent at room temperature is preheated by the preheater 100, and then enters the packing section 220 of the de-weighting concentration tower 200 (the packing section 220 includes 3 packing zones from bottom to top) from the first section from bottom to top for preliminary distillation; the switch of the circulating water pipeline 240 acting on the condenser 230 is turned on to control the pressure of the bottom of the de-weighting concentration tower 200 at 50 kPa, the bottom temperature at 90°C, and the top temperature at 55°C; the liquid phase of the crude pentane foaming agent flows to the bottom of the de-weighting concentration tower 200, and is gradually concentrated by heating in the heating section 210 (heating steam at 390 kg / h) to obtain a concentrated liquid. The liquid level in the bottom of the de-weighting concentration tower 200 is controlled at 45%. The concentrated liquid is transported to the preheater 100 through the de-weighting concentrate pipeline 250 to recover heat, and then collected by the concentrate pump 251;

[0133] Step 2: Stop adding azeotropic deoxygenated hot water (65℃) from azeotropic agent replenishment port 510 of azeotropic agent injection line 500. The top vapor phase of the heavy phase concentrator 200 enters the refining column 300 for distillation. The refining column 300 has 20 trays. Control the reboiler pressure of the refining column 300 at 50 kPa, the top pressure at 35 kPa, the reboiler temperature at 55℃, the top temperature at 46℃, and the reflux flow rate at 1.0 m³ / s. 3 / h;

[0134] Step 3: The vapor phase at the top of the refining tower 300 is condensed by the condenser 310 and collected in the condensate tank 400. The liquid level in the condensate tank 400 is controlled at 78%. When the DMF content in the condensate tank 400 is greater than 3 ppm and the chlorine element such as ammonium chloride is greater than 10 ppm, the flow rate of the reflux line 610 back to the refining tower 300 is adjusted to 1.25 times the original reflux flow rate. The pentane foaming agent is continuously drawn out from the finished product outlet pipeline 600.

[0135] Step 4: The bottom liquid of the refining tower 300 is transported through the bottom liquid pipeline 320 to the second section from top to bottom of the packing section 220 of the de-weighting and concentration tower 200 for secondary distillation. The bottom liquid in the refining tower 300 is controlled at 60%.

[0136] Under stable operation of the instruments and equipment in the de-concentration tower 200 and the purification tower 300 of this purification method, the pentane foaming agent crude product fed to the de-concentration tower 200 contains approximately 52% pentane, 25 ppm DMF, and 360 ppm ammonium chloride and other chlorine elements. Sampling analysis from the condensate tank 400 pipeline showed the following results: at 1h, 2h, 4h, 6h, and 8h, the purity, DMF content, and ammonium chloride and other chlorine element content of the pentane foaming agent were 60.2048%. (15ppm, 53.43ppm); (60.2145%, 15ppm, 52.12ppm); (60.6659%, 13ppm, 51.17ppm); (60.8499%, 13ppm, 51.99ppm); (60.9234%, 12ppm, 51.78ppm); When the addition of azeotropic agent is stopped, the purity of pentane foaming agent is only about 60%, and the chlorine content of DMF and ammonium chloride is reduced to the required level.

[0137] As can be seen from Comparative Case 1, the quality of pentane foaming agent cannot be improved without adding an azeotropic agent.

[0138] Comparison Case 2

[0139] A method for refining a pentane blowing agent, specifically including the following steps:

[0140] Step 1: The crude pentane foaming agent at room temperature is preheated by the preheater 100, and then enters the packing section 220 of the de-weighting concentration tower 200 (which includes three packing sections from bottom to top) from the third section from the bottom up for preliminary distillation; the switch of the circulating water pipeline 240 acting on the condenser 230 is turned on to control the pressure of the bottom of the de-weighting concentration tower 200 at 50 kPa, the bottom temperature at 90°C, and the top temperature at 55°C; the liquid phase of the crude pentane foaming agent flows to the bottom of the de-weighting concentration tower 200, and is gradually concentrated by heating in the heating section 210 (heating steam at 400 kg / h) to obtain a concentrated liquid. The liquid level in the bottom of the de-weighting concentration tower 200 is controlled at 45%. The concentrated liquid is transported to the preheater 100 through the de-weighting concentrate pipeline 250 to recover heat, and then collected by the concentrate pump 251;

[0141] Step 2: Add azeotropic deoxygenated hot water (65℃) to the azeotropic agent supply port 510 of the azeotropic agent injection line 500. The azeotropic agent flow rate is controlled at 10L / h. The vapor phase from the top of the heavy phase concentrator 200 enters the refining column 300 and undergoes rectification together with the added azeotropic agent. The refining column 300 has 20 trays. The bottom pressure of the refining column 300 is controlled at 50KPa, the top pressure at 35KPa, the bottom temperature at 55℃, and the top temperature at 46℃. The reflux flow rate is 1.0m³. 3 / h;

[0142] Step 3: The vapor phase from the top of the refining tower 300 is condensed in condenser 310 and collected in condensate tank 400. The liquid level in condensate tank 400 is controlled at 78%. When the DMF content in condensate tank 400 is greater than 3 ppm and the chlorine content (such as ammonium chloride) is greater than 10 ppm, the flow rate of reflux from reflux line 610 back to refining tower 300 is adjusted to 1.25 times the original reflux flow rate. The pentane foaming agent is continuously drawn from the finished product outlet line 600. The azeotropic agent, after being condensed from the top of refining tower 300 in condenser 310, is separated and collected in separator 410 of condensate tank 400. The liquid level in separator 410 is controlled at 60%, and the azeotropic agent is returned to refining tower 300 for recycling via azeotropic agent injection line 500. An azeotropic agent replenishment port 510 is installed on azeotropic agent injection line 500 to achieve stable control of the liquid level in separator 410.

[0143] Step 4: The bottom liquid of the refining tower 300 is transported through the bottom liquid pipeline 320 to the second section from top to bottom of the packing section 220 of the de-weighting and concentration tower 200 for secondary distillation. The bottom liquid in the refining tower 300 is controlled at 60%.

[0144] Under stable operation of the instruments and equipment in the de-concentration tower 200 and the purification tower 300 of this refining method, the pentane foaming agent crude product fed to the de-concentration tower 200 contains approximately 52% pentane, 25 ppm DMF, and 360 ppm ammonium chloride and other chlorine elements. Analysis of samples taken from the condensate tank 400 pipeline at 1h, 2h, 4h, 6h, and 8h showed the following purity, DMF content, and ammonium chloride and other chlorine element content of the pentane foaming agent: (65.3325%, 14 ppm, ...). (24.45ppm); (65.6576%, 13ppm, 25.35ppm); (64.9261%, 13ppm, 25.24ppm); (65.3429%, 12ppm, 24.73ppm); (63.9745%, 12ppm, 24.99ppm); When the feed inlet of the de-heavy concentration tower 200 is adjusted to the upper layer of the third section from the top, the purity of pentane foaming agent is only about 65%, and the chlorine elements such as DMF and ammonium chloride are reduced and do not meet the index requirements.

[0145] As can be seen from Comparative Case 2, adjusting the material to enter the packing section 220 of the deweighting and concentration tower 200 from the third segment from the bottom up does not improve the quality of the pentane foaming agent.

[0146] Comparison Case 3

[0147] A method for refining a pentane blowing agent, specifically including the following steps:

[0148] Step 1: The crude pentane foaming agent at room temperature is preheated by the preheater 100, and then enters the packing section 220 of the de-weighting concentration tower 200 (which includes three packing sections from bottom to top) from the first section from bottom to top for preliminary distillation. The switch of the circulating water pipeline 240 acting on the condenser section 230 is turned off, and the pressure of the bottom of the de-weighting concentration tower 200 is controlled at 50 kPa and the bottom temperature at 90°C. Due to the lack of circulating water reflux in the condenser section 230, the top temperature cannot be controlled and rises to 82°C. The liquid phase of the crude pentane foaming agent flows to the bottom of the de-weighting concentration tower 200 and is gradually concentrated by heating in the heating section 210 (heating steam is 380 kg / h) to obtain a concentrated liquid. The liquid level in the bottom of the de-weighting concentration tower 200 is controlled at 45%. The concentrated liquid is transported to the preheater 100 through the de-weighting concentrate pipeline 250 to recover heat, and then collected by the concentrate pump 251.

[0149] Step 2: Add azeotropic deoxygenated hot water (65℃) to the azeotropic agent supply port 510 of the azeotropic agent injection line 500. The azeotropic agent flow rate is controlled at 10L / h. The vapor phase from the top of the heavy phase concentrator 200 enters the refining column 300 and undergoes rectification together with the added azeotropic agent. The refining column 300 has 20 trays. The bottom pressure of the refining column 300 is controlled at 50KPa, the top pressure at 35KPa, the bottom temperature at 55℃, and the top temperature at 46℃. The reflux flow rate is 1.0m³. 3 / h;

[0150] Step 3: The vapor phase from the top of the refining tower 300 is condensed in condenser 310 and collected in condensate tank 400. The liquid level in condensate tank 400 is controlled at 78%. When the DMF content in condensate tank 400 is greater than 3 ppm and the chlorine content (such as ammonium chloride) is greater than 10 ppm, the flow rate of reflux from reflux line 610 back to refining tower 300 is adjusted to 1.25 times the original reflux flow rate. The pentane foaming agent is continuously drawn from the finished product outlet line 600. The azeotropic agent, after being condensed from the top of refining tower 300 in condenser 310, is separated and collected in separator 410 of condensate tank 400. The liquid level in separator 410 is controlled at 60%, and the azeotropic agent is returned to refining tower 300 for recycling via azeotropic agent injection line 500. An azeotropic agent replenishment port 510 is installed on azeotropic agent injection line 500 to achieve stable control of the liquid level in separator 410.

[0151] Step 4: The bottom liquid of the refining tower 300 is transported through the bottom liquid pipeline 320 to the second section from top to bottom of the packing section 220 of the de-weighting and concentration tower 200 for secondary distillation. The bottom liquid in the refining tower 300 is controlled at 60%.

[0152] Under stable operation of the instruments and equipment in the de-concentration tower 200 and the purification tower 300 of this refining method, the pentane component content in the crude pentane foaming agent fed to the de-concentration tower 200 is approximately 52%, the DMF content is 25 ppm, and the chlorine content (including ammonium chloride) is 360 ppm. Sampling analysis from the pipeline taken from the condensate tank 400 showed the following results: At 1h, 2h, 4h, 6h, and 8h, the purity, DMF content, and chlorine content (including ammonium chloride) of the pentane foaming agent were (58.9005%), 19 ppm, and 64.23 ppm, respectively; (5 (8.3681%, 18ppm, 63.51ppm); (58.0109%, 17ppm, 63.31ppm); (57.9951%, 18ppm, 62.58ppm); (58.1121%, 19ppm, 63.19ppm); When the circulating water pipeline 240 of the condenser section 230 on the de-heavy concentration tower 200 is closed, the cooling capacity in the tower system is reduced, resulting in an increase in the tower top temperature. The purity of the pentane foaming agent is only about 58%, and the chlorine elements such as DMF and ammonium chloride are reduced and do not meet the index requirements.

[0153] As can be seen from Comparative Case 3, when the switch of the circulating water pipeline 240 acting on the condenser section 230 is turned off, under the condition that the reflux flow rate and azeotropic dosage remain unchanged, the cooling amount is insufficient to reduce the heating amount, resulting in an increase in the temperature of each part of the tower system, and the quality of the pentane foaming agent cannot be improved.

[0154] Through comparison of the above implementation examples, the purification method for pentane blowing agent provided by this invention can effectively improve the quality of high-pentane blowing agent, increasing pentane purity from approximately 50% to greater than 70%, completely removing DMF to almost 0 ppm, and reducing the content of chlorine elements such as ammonium chloride to less than 10 ppm, even as low as below 5 ppm. The purification method offers high operational flexibility, and through heat recovery and utilization, it reduces the amount of steam used in the reboiler, achieving steam savings and significantly lowering production costs.

Claims

1. A C5 fraction refining system characterized by, include: The heavy weight removal and concentration tower (200) includes, from bottom to top, a heating section (210), a packing section (220), and a condensation section (230); A refining column (300) is connected to the condenser section (230) of the de-weighting and concentration column (200), and a condenser (310) is connected to the top of the refining column (300); the refining column (300) has 20 to 30 trays. A condensate tank (400) is connected to the condenser (310), and a separator (410) is provided on the condensate tank (400) for separating the azeotropic agent and the refined C5 fraction; An azeotropic agent injection line (500) is connected to the separator (410). The azeotropic agent injection line (500) is provided with an azeotropic agent replenishment port (510). The output end of the azeotropic agent injection line (500) is connected to the refining tower (300). The azeotropic agent can remove ammonium chloride and DMF solvent, eliminating the formation of ammonium chloride crystals. A finished product collection pipeline (600) is provided. The finished product collection pipeline (600) is also provided with a reflux pump (620) and connected to a reflux line (610). The reflux line (610) and the azeotropic agent injection line (500) are connected in parallel and merged into the refining tower (300). The packing section (220) comprises 3 to 5 sections from bottom to top, and the material enters the packing section (220) from the 1st to 2nd section from bottom to top; the deweighting and thickening tower (200) also includes a circulating water pipeline (240) for adjusting the temperature at the top of the deweighting and thickening tower (200).

2. The C5 fraction refining system of claim 1, wherein, The heating section (210) of the de-weighting concentration tower (200) is also connected to a de-weighting concentrate pipeline (250) for discharging the concentrate in the de-weighting concentration tower (200). The de-weighting concentrate pipeline (250) is connected to a preheater (100) for recovering the waste heat of the concentrate.

3. The C5 fraction refining system according to claim 1, characterized in that, The bottom of the refining tower (300) is connected to a bottom liquid pipeline (320), which is connected to the second to third section from top to bottom of the packing section (220) of the deweighting and concentration tower (200).

4. The C5 fraction refining system according to claim 1, characterized in that, The C5 fraction refining system also includes a reflux line (610) connected to the finished product collection line (600), and the reflux line (610) and the azeotropic agent injection line (500) are connected in parallel and merged into the refining tower (300).

5. A method for refining a pentane blowing agent, characterized in that, Purification using the C5 fraction purification system according to any one of claims 1-4 includes the following steps: Step 1: Add the crude pentane foaming agent from the first to second section from the bottom to the packed section (220) of the de-heavy concentration tower (200) for preliminary distillation; Step 2: Add azeotropic agent from the azeotropic agent replenishment port (510) of the azeotropic agent injection line (500). The vapor phase at the top of the deweighting and concentration tower (200) enters the purification tower (300) and is distilled together with the added azeotropic agent. Step 3: The vapor phase at the top of the refining tower (300) is condensed by the condenser (310) and collected in the condensate tank (400). At the same time, the flow rate of the product returning to the refining tower (300) in the reflux line (610) is adjusted according to the quality of the product in the condensate tank (400). The finished product is collected through the finished product collection line (600) to obtain the refined pentane foaming agent. Step 4: The bottom liquid of the refining tower (300) is transported through the bottom liquid pipeline (320) to the second to third section from top to bottom of the packing section (220) for secondary distillation.

6. The refining method according to claim 5, characterized in that, In step one, the preliminary distillation process is as follows: the pressure of the bottom of the deweighting and concentration tower (200) is controlled at 40KPa~55KPa, the bottom temperature is 70℃~95℃, and the top temperature is 50℃~60℃.

7. The refining method according to claim 5, characterized in that, In step two, the distillation process is as follows: the top pressure of the refining column (300) is controlled at 15KPa~40KPa, the bottom temperature of the refining column (300) is 50℃~60℃, and the top temperature of the refining column (300) is 38℃~50℃; the azeotropic agent is deoxygenated hot water; and the temperature of the azeotropic agent is 60℃~66℃.

8. The refining method according to claim 5, characterized in that, In step three, the azeotropic agent is condensed from the top of the refining tower (300) by the condenser (310), separated and collected in the separator (410) of the condensate tank (400), and then returned to the refining tower (300) for recycling via the azeotropic agent injection line (500).

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