A rectification separation apparatus and rectification separation method

Abstract

The application discloses a rectification separation device and method, and relates to the technical field of rectification separation.The rectification separation device comprises a separation tower group, the separation tower group comprises a plurality of separation towers which are sequentially arranged in series along a first direction, and the tower diameters of the plurality of separation towers gradually decrease in the first direction; and an exhaust port which is arranged at the top of the separation tower, and the exhaust port of the previous separation tower is connected to the feed inlet of the next separation tower through a conveying pipeline.The rectification separation device solves the technical problem that the existing rectification separation device has a large equipment size and high energy consumption due to the large evaporation capacity required in the separation tower, the maximum gas-liquid load of the plurality of separation towers gradually decreases according to the optimal gas-liquid load curve in the separation tower, and the gas-liquid load in each separation tower is close to the optimal gas-liquid load in the separation tower, so that the required product is output while the energy consumption of the whole device is effectively reduced and the equipment size is reduced.

Description

Technical Field

[0001] This invention relates to the field of distillation separation technology, and in particular to a distillation separation apparatus and a distillation separation method. Background Technology

[0002] Processes such as stable isotope enrichment and isomer separation are characterized by extremely small overall separation coefficients α (≤1.008), huge evaporation requirements in the column, and often more than 2000 theoretical plates. These characteristics make stable isotope separation exceptionally difficult and costly. Cryogenic distillation, a method for separating mixed gases at extremely low temperatures through distillation, is widely used in air separation, natural gas processing, and chemical industries. This technology utilizes the differences in boiling points of different components to achieve efficient separation under cryogenic conditions. It is suitable for difficult-to-separate systems and therefore can be applied to the field of stable isotope enrichment.

[0003] However, existing distillation separation devices suffer from large equipment size and high energy consumption due to the huge evaporation requirements within the separation tower. Therefore, a distillation separation device and method are proposed to address these issues. Summary of the Invention

[0004] The purpose of this invention is to provide a distillation separation device and a distillation separation method, which solves the technical problems of existing distillation separation devices having large equipment size and high energy consumption due to the huge evaporation requirements in the separation tower.

[0005] To achieve the above objectives, the present invention provides a distillation separation apparatus, comprising:

[0006] A separation tower group, comprising: a plurality of separation towers arranged in series along a first direction, wherein the diameter of the plurality of separation towers decreases sequentially along the first direction, so that the maximum gas-liquid load of the plurality of separation towers decreases step by step;

[0007] An exhaust port is located at the top of the separation tower. The exhaust port of the previous separation tower is connected to the feed port of the next separation tower through a conveying pipe. The exhaust port of the last separation tower is connected to a storage device.

[0008] A drain outlet is located at the bottom of the separation tower, and the drain outlet is used to discharge the waste liquid in the separation tower;

[0009] A heater is provided at the bottom of the separation tower, and the heater is used to increase the amount of evaporated gas at the bottom of the tower;

[0010] An adsorption purification device is connected to the first separation tower. The adsorption purification device is used to purify the light isotope raw material to obtain a raw material gas and to deliver the raw material gas to the first separation tower.

[0011] Preferably, the adsorption purification device is connected to a heat exchanger, the hot end inlet of the heat exchanger is used to input light isotope gas, the hot end outlet of the heat exchanger is connected to the feed inlet of the adsorption purification device, and the drain outlet of the first separation tower is connected to the first cold end inlet of the heat exchanger. The drain outlets of the other separation towers besides the first separation tower are all connected to a storage tank, and the storage tank is connected to the second cold end inlet of the heat exchanger.

[0012] Preferably, each of the separation towers is equipped with a condenser at the top, the condenser is filled with atmospheric pressure liquid nitrogen, and the liquid nitrogen level in the condenser is 1 / 3 of the design level.

[0013] Preferably, a shut-off valve is installed on the conveying pipeline between two adjacent separation towers, and the shut-off valve is used to control the opening and closing of the conveying pipeline.

[0014] Accordingly, the present invention also provides a distillation separation method, applied to the distillation separation apparatus described in any of the above claims, the distillation separation method comprising:

[0015] Light isotope raw materials are controlled to enter the adsorption purification device for purification to obtain raw material gas. The raw material gas enters the first separation tower and condenses at the top of the first separation tower to form a liquid accumulation at the bottom of the first separation tower.

[0016] Once the liquid level at the bottom of the first separation tower reaches the set value, the heater at the bottom of the first separation tower is turned on to increase the amount of evaporated gas at the bottom of the tower to the maximum value, thereby obtaining product gas and controlling the first separation tower to establish an abundance gradient.

[0017] After the abundance gradient is established in the previous separation tower, the delivery pipeline is slowly opened and the heater in the previous separation tower is gradually shut off. The product gas at the top of the previous separation tower enters the top of the next separation tower through the delivery pipeline, condenses, and forms a liquid accumulation at the bottom of the next separation tower.

[0018] Once the liquid level at the bottom of the next separation tower reaches the set value, the heater at the bottom of the next separation tower is turned on to increase the amount of evaporated gas at the bottom of the tower to the maximum value, thereby obtaining product gas.

[0019] Once each of the separation columns in the overall distillation and separation unit reaches distillation equilibrium, the product gas obtained from the top of the last separation column is the desired high-abundance light isotope gas.

[0020] Preferably, after the step of turning on the heater at the bottom of the next separation column to increase the bottom evaporation gas volume to a maximum value and obtain product gas, the method further includes: controlling the full reflux operation at the beginning stage of each separation column to make the mass transfer driving force in the previous separation column reach the design maximum value, so as to accelerate the distillation equilibrium rate of each separation column.

[0021] Preferably, the steps to be achieved by each of the separation columns in the overall distillation and separation device further include: the heater at the bottom of each separation column is not turned on under normal operating conditions, and the liquid at the bottom of each separation column is maintained at a certain level.

[0022] Preferably, before the step of controlling the light isotope raw material to enter the adsorption purification device for purification to obtain raw material gas, the method further includes: controlling the overall distillation separation device to be evacuated so that the vacuum degree inside the overall distillation separation device is not less than the set vacuum degree. After the vacuum degree inside the overall distillation separation device is qualified, the instrument control is checked to see if it is working properly. After the instrument control is checked, the temperature inside each of the separation towers is controlled to be reduced until the temperature inside each of the separation towers is 10-15°C higher than the design temperature.

[0023] Preferably, the step of controlling and reducing the temperature inside each of the separation towers includes: installing a condenser at the top of each separation tower, filling the condenser with atmospheric pressure liquid nitrogen, and setting the liquid nitrogen level in the condenser to 1 / 3 of the design level, thereby reducing the temperature inside the separation tower through heat exchange.

[0024] Preferably, after the step of each separation column in the overall distillation and separation unit reaching distillation equilibrium, the method further includes:

[0025] When it is necessary to collect light isotope gases of different abundance levels, the heater at the bottom of the corresponding separation tower is activated to increase the mass transfer driving force in the corresponding separation tower, thereby increasing the gas-liquid load in the corresponding separation tower.

[0026] After obtaining more light isotope gas of the corresponding abundance at the top of the corresponding separation tower, the excess light isotope gas in the corresponding separation tower is extracted, and the remaining light isotope gas enters the next separation tower to continue enriching the light isotope gas of the corresponding abundance in the next separation tower.

[0027] Compared to the aforementioned background technology, the distillation separation apparatus provided by this invention has the following beneficial effects: By connecting multiple separation towers with different maximum gas-liquid loads in series, and setting several separation towers with different diameters according to the optimal gas-liquid load curves within the separation towers, with the maximum gas-liquid load of the several separation towers decreasing progressively, the gas-liquid load in each separation tower is made sufficiently close to the optimal gas-liquid load within the separation tower during the actual separation process of the light isotope gas. This reduces the energy consumption of the entire apparatus and the size of the equipment while producing the desired product. On the other hand, by activating the heaters at the bottom of the corresponding separation towers, the mass transfer driving force within the corresponding separation towers is increased, thereby increasing the gas-liquid load within the corresponding separation towers. This allows for the acquisition of more light isotope gas of the corresponding abundance at the top of the corresponding separation towers, and the extraction of excess light isotope gas from the corresponding separation towers. This enables the continuous production of light isotope gas of different abundance levels from the corresponding separation towers, resulting in better practicality. The distillation separation method used in this invention also possesses the above-mentioned beneficial effects. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the optimal gas-liquid load curve in the separation tower provided in an embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of the actual gas-liquid load curve inside the separation tower provided in an embodiment of the present invention;

[0031] Figure 3 This is a schematic diagram illustrating the working principle of the distillation and separation apparatus provided in an embodiment of the present invention.

[0032] Specifically, 1-Separation tower; 2-Heater; 3-Adsorption purification device; 4-Heat exchanger; 401-Hot end inlet; 402-Hot end outlet; 403-First cold end inlet; 404-Second cold end inlet; 405-First cold end outlet; 406-Second cold end outlet; 5-Transfer pipeline; 501-Stop valve; 6-Storage tank. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] like Figure 1 As shown, to achieve the above objectives, the present invention provides a distillation separation apparatus, comprising: a separation tower group 1 and an adsorption purification device 3.

[0036] The separation tower group 1 includes several separation towers 1 connected in series, with the tower diameters of the several separation towers 1 decreasing sequentially, so that the maximum gas-liquid load of the several separation towers 1 decreases step by step. That is, the several separation towers 1 are set in sections, so that in the actual separation process of light isotope gas, the gas-liquid load in each separation tower 1 is close to the optimal gas-liquid load in the separation tower 1, thereby reducing the energy consumption of the entire set of equipment and reducing the equipment size while producing the required product. It should be noted that multiple separation towers 1 with the same segmented tower diameter can be connected in parallel.

[0037] The top of the separation tower 1 is provided with an exhaust port. In the same group of separation towers 1, the exhaust port of the previous separation tower 1 is connected to the feed port of the next separation tower 1 through the conveying pipe 5 to ensure that the product gas at the top of the previous separation tower 1 enters the top of the next separation tower 1 through the conveying pipe 5. In addition, the product gas obtained at the top of the last separation tower 1 is the desired high abundance light isotope gas. It is connected to a storage device through the exhaust port on the last separation tower 1 to transport the product gas obtained at the top of the last separation tower 1 to the storage device for preservation.

[0038] The bottom of the separation tower 1 is equipped with a drain port, which is used to discharge the waste liquid in the separation tower 1. A drain valve is installed at the drain port to control the opening and closing of the drain port. When there is a lot of waste liquid at the bottom of the separation tower 1 that needs to be cleaned, the drain valve is opened to safely discharge the waste liquid and ensure the normal operation of the entire distillation and separation unit.

[0039] A heater 2 is installed at the bottom of the separation tower 1. The heater 2 is used to increase the amount of evaporated gas at the bottom of the tower to obtain product gas. Specifically, the heater 2 is an electric heater. The electric heater increases the amount of evaporated gas at the bottom of the tower to its maximum value, thereby enhancing the mass transfer driving force of the separation tower 1 and obtaining product gas.

[0040] With attachment Figure 1Taking the orientation shown as an example, the leftmost separation tower 1 is connected to the adsorption purification device 3. The adsorption purification device 3 is used to purify the light isotope raw material. Specifically, it selectively adsorbs impurities in the light isotope gas to obtain the raw material gas by adsorption, thereby achieving the purpose of preliminary purification, and then transports the purified raw material gas to the first separation tower.

[0041] In operation, the light isotope raw material is controlled to enter the adsorption purification device 3 for purification to obtain raw material gas. The raw material gas enters the first separation tower and condenses at the top of the first separation tower, forming a liquid accumulation at the bottom of the first separation tower. After the liquid level at the bottom of the first separation tower reaches the set value, the heater 2 at the bottom of the first separation tower is turned on to increase the evaporation rate at the bottom of the tower to the maximum value, thereby obtaining product gas and controlling the first separation tower to establish an abundance gradient. After the previous separation tower 1 has established an abundance gradient, the conveying pipe 5 is slowly opened, and the heater 2 in the previous separation tower 1 is gradually turned off. The product gas at the top of the previous separation tower 1 enters the top of the next separation tower 1 through the conveying pipe 5 and condenses at the bottom of the next separation tower 1, forming a liquid accumulation at the bottom of the next separation tower 1. After the liquid level at the bottom of the next separation tower 1 reaches the set value, the heater 2 at the bottom of the next separation tower 1 is turned on to increase the evaporation rate at the bottom of the tower to the maximum value, thereby obtaining product gas. After all the separation towers 1 in the overall distillation separation device reach distillation equilibrium, the product gas obtained at the top of the last separation tower 1 is the desired high-abundance light isotope gas. By setting up separation towers 1 with different diameters, the gas-liquid load in separation tower 1 during the deep cryogenic precision separation process is made close to the ideal cascade. This reduces the gas-liquid load in the overall distillation and separation unit while meeting the separation performance requirements of separation tower 1 in the corresponding segment, thereby reducing energy consumption.

[0042] In one embodiment of the present invention, the adsorption purification device 3 is connected to a heat exchanger 4. The heat exchanger 4 is provided with a hot end inlet 401, a hot end outlet 402, a first cold end inlet 403, a second cold end inlet 404, a first cold end outlet 405, and a second cold end outlet 406. Specifically, the hot end inlet 401 of the heat exchanger 4 is used to input light isotope gas, the hot end outlet 402 of the heat exchanger 4 is connected to the feed inlet of the adsorption purification device 3, and the drain outlet of the first separation tower is connected to the first cold end inlet 403 of the heat exchanger 4. The drain outlets of the other separation towers 1, except for the first separation tower, are all connected to a storage tank 6, and the storage tank 6 is connected to the second cold end inlet 404 of the heat exchanger 4. Specifically, the waste liquid at the bottom of the first separation tower is recovered from the first cold end inlet 403 and enters the heat exchanger 4, which serves to cool the light isotope raw material, improve the system's cooling efficiency, and reduce the device's energy consumption. The waste liquid at the bottom of the other separation towers 1, except for the first separation tower, is discharged through the drain port and then enters the storage tank 6 for storage. After being discharged from the storage tank 6, it is further recovered from the second cold end inlet 404 and enters the heat exchanger 4, which also plays the role of cooling the light isotope raw materials, further improving the system's cold energy utilization efficiency and reducing the energy consumption of the device.

[0043] It should be noted that the waste liquid entering the first cold end inlet 403 exchanges heat with the light isotope raw material and is discharged from the first cold end outlet 405. The waste liquid entering the second cold end inlet 404 exchanges heat with the light isotope raw material and is discharged from the second cold end outlet 406. Finally, they are both transported to the high-purity light isotope system for storage for subsequent use.

[0044] It should be noted that a condenser (not shown in the figure) is installed at the top of each separation tower 1. The condenser is filled with atmospheric pressure liquid nitrogen to shorten the cooling time of the separation tower 1 until the internal temperature of the separation tower 1 is 10-15°C higher than the design temperature, at which point the supply of liquid nitrogen to the condenser is stopped. Preferably, the liquid nitrogen level in the condenser is 1 / 3 of the design level, which ensures that the condenser always has sufficient liquid nitrogen for heat exchange, while also ensuring uniform distribution of liquid nitrogen within the condenser, thus improving heat exchange efficiency.

[0045] In one embodiment of the present invention, a shut-off valve 501 is provided on the conveying pipe 5 between two adjacent separation towers 1. The shut-off valve 501 is used to control the opening and closing of the conveying pipe 5, thereby precisely controlling the connection timing between the two adjacent separation towers 1, so as to ensure that the conveying pipe 5 is slowly opened after the previous separation tower 1 has completed the establishment of the abundance gradient, thereby maximizing the efficiency of each separation tower 1 in the overall distillation separation device to achieve distillation balance.

[0046] The gas-liquid-solid three-phase integrated separation method adopted in this invention specifically includes the following steps: Light isotope raw materials are controlled to enter the adsorption purification device 3 for purification to obtain raw material gas. The raw material gas enters the first separation tower and condenses at the top of the first separation tower, forming a liquid accumulation at the bottom of the first separation tower. After the liquid level at the bottom of the first separation tower reaches a set value, the heater 2 at the bottom of the first separation tower is turned on to increase the evaporation gas flow rate at the bottom of the tower to its maximum value, obtaining product gas, and controlling the first separation tower to establish an abundance gradient. After the previous separation tower 1 has established an abundance gradient, the conveying pipeline 5 is slowly opened, and the heater 2 in the previous separation tower 1 is gradually turned off. The product gas at the top of one separation tower 1 enters the top of the next separation tower 1 through the conveying pipe 5 and condenses to form a liquid accumulation at the bottom of the next separation tower 1. After the liquid level at the bottom of the next separation tower 1 reaches the set value, the heater 2 at the bottom of the next separation tower 1 is turned on to increase the amount of gas evaporated at the bottom of the tower to the maximum value, thereby obtaining product gas. The initial stage of each separation tower 1 is controlled to operate under full reflux, so that the mass transfer driving force in the previous separation tower 1 reaches the design maximum value, thereby accelerating the distillation equilibrium speed of each separation tower 1. After all the separation towers 1 in the overall distillation separation device reach distillation equilibrium, the product gas obtained at the top of the last separation tower 1 is the desired high-abundance light isotope gas.

[0047] It should be noted that the step of waiting for each separation column 1 in the overall distillation separation unit to reach distillation equilibrium also includes: the heater 2 at the bottom of each separation column 1 is not turned on under normal operating conditions, and the liquid at the bottom of each separation column 1 is kept at a certain level. At this time, the waste liquid in each separation column 1 is safely discharged through the drain valve.

[0048] In one embodiment of the present invention, before the step of controlling the light isotope raw material to enter the adsorption purification device 3 for purification to obtain the raw material gas, the method further includes: controlling the overall distillation separation device to be evacuated, so that the vacuum degree inside the overall distillation separation device is not less than the set vacuum degree. After the vacuum degree inside the overall distillation separation device is qualified, the instrument and control are checked to see if they are working properly. After the instrument and control are checked, the temperature inside each separation tower 1 is controlled to be reduced until the temperature inside each separation tower 1 is 10-15°C higher than the design temperature. Specifically, atmospheric pressure liquid nitrogen is injected into the condenser, and the liquid nitrogen level in the condenser is 1 / 3 of the design level, thereby reducing the temperature inside the separation tower 1 through heat exchange.

[0049] In one embodiment of the present invention, after the step of each separation column 1 in the overall distillation separation device reaching distillation equilibrium, the method further includes:

[0050] When it is necessary to collect light isotope gases of different abundance levels, the heater 2 at the bottom of the corresponding separation tower 1 is activated to increase the mass transfer driving force within the corresponding separation tower 1, thereby increasing the gas-liquid load within the corresponding separation tower 1. After more light isotope gases of the corresponding abundance level are obtained at the top of the corresponding separation tower 1, the excess light isotope gases in the corresponding separation tower 1 are extracted. This allows for the collection of light isotope gases from the corresponding separation tower 1 as needed, thus continuously producing light isotope gases of different abundance levels, improving practicality. In addition, the remaining light isotope gases enter the next separation tower 1 to continue enriching the corresponding abundance light isotope gases in the next separation tower 1, without obtaining the required high abundance light isotope gases at the top of the last separation tower 1.

[0051] With light isotopes For example, the specific implementation method is as follows:

[0052] like Figure 2 As shown, the optimal gas-liquid load curve in separation tower 1, n s For the theoretical plate number of the impoverished segment, n e This represents the theoretical plate number of the enriched segment. The liquid load of the i-th mass transfer plate in the enrichment section. For the gas load of the j-th mass transfer plate in the depletion section, For waste liquid discharge, The required output.

[0053] It should be noted that when adjusting the optimal gas-liquid load in separation tower 1, the feed point... The required gas-liquid load is highest at the feed point, and gradually decreases from the feed end to the concentrate end and waste liquid end, reaching zero at the concentrate end and waste liquid end. Therefore, multiple separation columns 1 with different diameters are set up so that the gas-liquid load in each separation column 1 is close to the optimal gas-liquid load in the separation column 1, thereby making the overall distillation separation unit more compact and improving the overall distillation efficiency.

[0054] like Figure 1 and Figure 2 As shown, based on the optimal gas-liquid load curve within separation tower 1, separation towers i-1, i-2, i-3, i-4, i-5, ..., im, and in are segmented to achieve different abundance levels. Continuous production of the product. The exhaust port of separation tower i-1 is connected to the inlet of separation tower i-2 via a first conveying pipe. A first shut-off valve 501 is installed on the first conveying pipe to control its opening and closing. Similarly, the exhaust port of separation tower i-2 is connected to the inlet of separation tower i-3 via a second conveying pipe. A second shut-off valve 501 is installed on the second conveying pipe to control its opening and closing. The connection method between adjacent separation towers 1 in separation towers i-1, i-2, i-3, i-4, i-5, ..., im, and in is the same, so it will not be described in detail further.

[0055] like Figure 3 As shown, separation towers i-1, i-2, i-3, i-4, i-5, ..., im and in are all rectangular counter-current symmetrical cascade towers. The split ratio Z in each separation tower 1 is 0.5. Specifically, the curve represents the optimal quantitative value of gas-liquid load in the tower, and the abundance change in separation tower 1 is characterized as follows:

[0056] ,in:

[0057] k represents the coefficient, ε represents the concentration coefficient, i represents the number of mass transfer plates, and z represents the abundance distribution.

[0058] The loads N1 to N5, ..., Nm and Nn in each stage of the separation tower 1 must meet certain conditions with the optimal quantified values ​​of the gas-liquid loads in the separation tower 1 in order to ensure that a positive abundance gradient is established inside the separation tower 1.

[0059] Before starting the integrated distillation and separation unit, a vacuum is evacuated to ensure the vacuum level is not less than the set vacuum level (759.9 Torr). After the vacuum level is deemed acceptable, the instrument's electrical control system is checked for proper operation. Once this check is complete, the temperature inside each separation column 1 is lowered until it is 10–15°C higher than the design temperature. Specifically, atmospheric pressure liquid nitrogen is introduced into the condenser, with the nitrogen level reaching one-third of the design level. This heat exchange reduces the temperature inside the separation column 1, shortening the cooling time of the integrated distillation and separation unit.

[0060] raw material After being purified by adsorption purification device 3, the gas enters separation tower i-1. After the gas condenses at the top of the i-1 separator, it accumulates at the bottom. Once the liquid level at the bottom of the i-1 separator reaches the set value, heater 2 at the bottom of the i-1 separator is turned on, and the amount of gas evaporated at the bottom of the separator is slowly increased to the design maximum value. The i-1 separator is controlled to operate under full reflux in the initial stage, so that the mass transfer driving force in the i-1 separator reaches the design maximum value, thereby accelerating the distillation equilibrium rate of the i-1 separator.

[0061] After establishing an abundance gradient in the i-1 separation column, the first shut-off valve 501 is slowly opened, allowing the product gas from the top of the i-1 column to enter the i-2 separation column. After condensation at the top of the i-2 column, the gas accumulates at the bottom. Once the liquid level at the bottom of the i-2 column reaches the set value, the heater 2 at the bottom of the i-2 column is activated, slowly increasing the evaporation rate to the design maximum. Similar to the i-1 separation column, the i-2 separation column is initially controlled to operate under full reflux to maximize the mass transfer driving force within it, thereby accelerating the distillation equilibrium rate.

[0062] After establishing an abundance gradient in the i-2 separation column, the second shut-off valve 501 is slowly opened. Simultaneously, the heater 2 at the bottom of the i-2 separation column is gradually shut off. The product gas from the top of the i-2 separation column enters the i-3 separation column, condenses at the top, and accumulates at the bottom. Once the liquid level at the bottom of the i-3 separation column reaches the set value, the heater 2 at the bottom of the i-3 separation column is turned on, and the evaporation gas flow rate at the bottom of the column is slowly increased to the design maximum value. Similar to the i-2 separation column, the i-3 separation column is initially controlled to operate under full reflux to bring the mass transfer driving force within the i-3 separation column to the design maximum value, thereby accelerating the distillation equilibrium rate of the i-3 separation column. The second shut-off valve 501 is then opened.

[0063] The startup operations for subsequent separation towers i-4, i-5, ..., im, and in are similar to those for i-1, i-2, and i-3, and will not be repeated here. The top of the last separation tower 1i-n is the desired high abundance level. .

[0064] It should be noted that the abundance distribution within one of the separation towers 1 corresponds to the distribution of the separation stages. The relationship, where z is Abundance, i represents the separation stage, ε represents the concentration coefficient; k is the relative flow rate, which is related to the ratio of the optimal gas-liquid load in the column to the actual gas-liquid load in separation column 1. k must be positive to ensure the concentration of gas within separation column 1. As the abundance increases along the separation stage, and along the movement path of the feed gas, the gas-liquid load in each separation tower 1 is controlled to decrease progressively. This means there is a flow contraction between each subsequent separation tower 1, and the minimum gas-liquid load L of each separation tower 1 is limited. The gas-liquid load ratio between successive separation towers 1 can meet the requirements. The requirements for k for efficient enrichment.

[0065] It should be further noted that for the production of different abundance levels Then, the gas-liquid load inside the i-1 to i-5 separation towers, ..., im and in separation towers needs to be increased accordingly. Specifically, when it is necessary to take the low abundance at the top of the i-1 separation tower... Then, heater 2 at the bottom of separation tower 1 is started, gradually increasing the gas-liquid load in separation tower i-1. As the gas-liquid load in separation tower i-1 increases, the mass transfer driving force in separation tower i-1 increases accordingly. With the increase of the mass transfer driving force inside separation tower i-1, more low-abundance gas can be obtained at the top of the tower. Product J, excess material was extracted. As products, the rest Proceed to the next separation tower 1 to continue enrichment. .

[0066] Similar to the operation of the i-1 separation tower, by adjusting the evaporation power of the heater 2 at the bottom of the subsequent separation tower 1, the gas-liquid load in the separation tower 1 is increased, thereby enhancing the mass transfer driving force without affecting the high abundance at the top of the in separation tower. Under the premise of production volume, produce other abundance levels. .

[0067] It should be noted that the liquid accumulated at the bottom of separation towers i-1 to i-5, ..., im and in is for producing different abundance grades. If the bottom liquid level of one of the separation towers (tower 1) falls below the warning value, the evaporation power of the bottom electric heater must be reduced, and the abundance of that product must also be reduced. The production rate is maintained until the liquid level at the bottom of the separator returns to the set level, ensuring normal production of high abundance at the top of the stage separator. .

[0068] In summary, based on the optimal gas-liquid load curve in separation tower 1, several separation towers 1 with different diameters are set up, and the maximum gas-liquid load of several separation towers 1 is gradually reduced. This ensures that during the actual separation process of light isotope gas, the gas-liquid load in each separation tower 1 is close to the optimal gas-liquid load in separation tower 1, thereby effectively reducing the energy consumption of the entire unit and reducing the equipment size while producing the required product.

[0069] It should be noted that in this specification, relational terms such as first and second are used only to distinguish one entity from several other entities, and do not necessarily require or imply any such actual relationship or order between these entities.

[0070] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the present invention.

Claims

1. A distillation separation method, applied to a distillation separation apparatus, characterized in that, The distillation separation apparatus includes: a separation column group, wherein the separation column group includes: a plurality of separation columns arranged in series along a first direction, the first separation column being connected to an adsorption purification device, and each separation column having a heater at its bottom; The distillation separation method includes: Light isotope raw materials are controlled to enter the adsorption purification device for purification to obtain raw material gas. The raw material gas enters the first separation tower and condenses at the top of the first separation tower to form a liquid accumulation at the bottom of the first separation tower. Once the liquid level at the bottom of the first separation tower reaches the set value, the heater at the bottom of the first separation tower is turned on to increase the amount of evaporated gas at the bottom of the tower to the maximum value, thereby obtaining product gas and controlling the first separation tower to establish an abundance gradient. After the abundance gradient is established in the previous separation tower, the delivery pipeline is slowly opened and the heater in the previous separation tower is gradually shut off. The product gas at the top of the previous separation tower enters the top of the next separation tower through the delivery pipeline, condenses, and forms a liquid accumulation at the bottom of the next separation tower. Once the liquid level at the bottom of the next separation tower reaches the set value, the heater at the bottom of the next separation tower is turned on to increase the amount of evaporated gas at the bottom of the tower to the maximum value, thereby obtaining product gas. Once each of the separation columns in the overall distillation and separation unit reaches distillation equilibrium, the product gas obtained from the top of the last separation column is the desired high-abundance light isotope gas.

2. The distillation separation method according to claim 1, characterized in that, After the step of turning on the heater at the bottom of the next separation column to increase the bottom evaporation gas flow to a maximum value and obtain product gas, the method further includes: controlling the initial stage of full reflux operation of each separation column to bring the mass transfer driving force in the previous separation column to a design maximum value, thereby accelerating the distillation equilibrium rate of each separation column.

3. The distillation separation method according to claim 1, characterized in that, The step of achieving distillation equilibrium in each of the separation columns in the overall distillation and separation device further includes: the heater at the bottom of each separation column is not turned on under normal operating conditions, and the liquid at the bottom of each separation column is maintained at a certain level.

4. The distillation separation method according to claim 1, characterized in that, Before the step of controlling the light isotope raw material to enter the adsorption purification device for purification to obtain raw material gas, the method further includes: controlling the overall distillation separation device to be evacuated so that the vacuum degree inside the overall distillation separation device is not less than the set vacuum degree. After the vacuum degree inside the overall distillation separation device is qualified, the instrument control is checked to see if it is working properly. After the instrument control is checked, the temperature inside each of the separation towers is controlled to be reduced until the temperature inside each of the separation towers is 10-15°C higher than the design temperature.

5. The distillation separation method according to claim 4, characterized in that, The step of controlling and reducing the temperature inside each of the separation towers includes: installing a condenser at the top of each separation tower, filling the condenser with atmospheric pressure liquid nitrogen, and setting the liquid nitrogen level in the condenser to 1 / 3 of the design level, thereby reducing the temperature inside the separation tower through heat exchange.

6. The distillation separation method according to claim 1, characterized in that, After the step of each separation column in the overall distillation and separation unit reaching distillation equilibrium, the method further includes: When it is necessary to collect light isotope gases of different abundance levels, the heater at the bottom of the corresponding separation tower is activated to increase the mass transfer driving force in the corresponding separation tower, thereby increasing the gas-liquid load in the corresponding separation tower. After obtaining more light isotope gas of the corresponding abundance at the top of the corresponding separation tower, the excess light isotope gas in the corresponding separation tower is extracted, and the remaining light isotope gas enters the next separation tower to continue enriching the light isotope gas of the corresponding abundance in the next separation tower.

7. The distillation separation method according to claim 1, characterized in that, The distillation and separation apparatus further includes: a separation tower group, which includes: a plurality of separation towers arranged in series along a first direction, wherein the diameter of the plurality of separation towers decreases sequentially along the first direction, so that the maximum gas-liquid load of the plurality of separation towers decreases step by step; An exhaust port is located at the top of the separation tower. The exhaust port of the previous separation tower is connected to the feed port of the next separation tower through a conveying pipe. The exhaust port of the last separation tower is connected to a storage device. A drain outlet is located at the bottom of the separation tower, and the drain outlet is used to discharge the waste liquid in the separation tower; A heater is provided at the bottom of the separation tower, and the heater is used to increase the amount of evaporated gas at the bottom of the tower; An adsorption purification device is connected to the first separation tower, the adsorption purification device being used to purify the light isotope raw material to obtain a raw material gas and to deliver the raw material gas to the first separation tower.

8. The distillation separation method according to claim 7, characterized in that, The adsorption purification device is connected to a heat exchanger. The hot end inlet of the heat exchanger is used to input light isotope raw materials, and the hot end outlet of the heat exchanger is connected to the feed inlet of the adsorption purification device. The drain outlet of the first separation tower is connected to the first cold end inlet of the heat exchanger. The drain outlets of the other separation towers, except for the first separation tower, are all connected to a storage tank. The storage tank is connected to the second cold end inlet of the heat exchanger.

9. The distillation separation method according to claim 7, characterized in that, Each of the separation towers is equipped with a condenser at the top, which is filled with atmospheric pressure liquid nitrogen, and the liquid nitrogen level in the condenser is 1 / 3 of the design level.

10. The distillation separation method according to claim 7, characterized in that, A shut-off valve is installed on the conveying pipeline between two adjacent separation towers, and the shut-off valve is used to control the opening and closing of the conveying pipeline.

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