TW201837011A - Propylene purification method and purification device - Google Patents

Abstract

Provided is a method for purifying propylene from a raw material comprising propylene and impurities. In an absorption column 1 having a temperature adjustment function, a first step is carried out in which the raw material is placed in contact with a silver ion-containing solution (an absorbent) under a first temperature and a first pressure so that the absorbent preferentially absorbs the propylene in the raw material while the unabsorbed gas that was not absorbed by the absorbent is discharged under a second temperature condition which is at or lower than the first temperature through a mist eliminator 4 that has a temperature adjustment function independent of the absorption column 1. In a stripping column 2, a second step is carried out in which the propylene in the absorbent which has been subjected to the first step is desorbed therefrom and recovered under a third temperature and a second pressure. The first step and the second step are carried out continuously in parallel while the absorbent is circulated between the absorption column 1 and the stripping column 2. In the first step, the percentage of raw material that escapes without being absorbed by the absorbent and is disposed as unabsorbed gas is adjusted to be within a range of 1 to 20 mol%.

Description

Purification method and purification equipment for propylene

The present invention relates to a method and an apparatus for concentrating and purifying propylene from a raw material containing propylene as a main component.

Although propylene, which is one example of a lower olefin, is known as a raw material of a synthetic resin product or a synthetic rubber product, such as polypropylene or acrylonitrile, it is also advantageously used in the field of electronic materials such as semiconductors. In the related applications, extremely high purity propylene is required.

A raw material gas containing propylene as a main component used as a highly purified raw material contains, for example, propane as an impurity. As a method of purifying the propylene from the source gas, for example, distillation, membrane separation, adsorption separation, or absorption separation is known.

In the absorption separation, for example, by using an absorption liquid of an aqueous solution of silver nitrate, propylene is purified by the interaction of olefin and silver (see, for example, Patent Document 1).

In the absorption separation by the absorption liquid using the aqueous solution of silver nitrate, the high-purity raw material may be further high-purity, and for example, the concentration of propylene of the raw material in Patent Document 1 is 98 to 99.5 mol%. However, it is difficult to purify a raw material (crude propylene gas) of such a lower purity than that which can be utilized in the field of electronic materials such as semiconductors. In recent years, there has been an increase in the number of low-priced raw materials including a large amount of impurities, and from the viewpoint of cost reduction, the need to purify the high-purity propylene from the low-priced raw material has increased. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 5546447

The present invention has been proposed in consideration of such a case, and provides a method of purifying a high-purity propylene having a relatively low purity crude propylene raw material and purifying it to a predetermined concentration or higher (for example, in an electronic material field such as a semiconductor). the main purpose. Further, in recent years, in addition to propane, a relatively low-priced raw material containing impurities other than propane (for example, oxygen, nitrogen, carbon dioxide, carbon monoxide, methane, ethane, butane, etc.) is increased, and it is more desirable to simultaneously carry out the Removal of impurities other than propane.

According to a first aspect of the present invention, there is provided a method for purifying propylene from a raw material containing propylene and impurities. The method is included in an absorption tower having a temperature adjustment function, and the raw material is brought into contact with an absorption liquid containing silver ions at a first temperature and a first pressure, and propylene in the raw material is preferentially absorbed by the absorption liquid, and a defogger having a temperature adjustment function independent of the absorption tower, a first step of discharging a non-absorbed gas that is not absorbed by the absorption liquid at a second temperature lower than the first temperature, and a stripping tower a second step of recovering propylene by the stripping of the absorbing liquid in the first step at a third temperature and a second pressure, while circulating the absorbing liquid between the absorption tower and the stripper, and continuously At the same time as the first step and the second step, in the first step, the ratio of the non-absorbed gas which is not absorbed by the absorption liquid and is blown off by the absorption liquid is adjusted to a range of 1 to 20 mol%. , obtaining high purity propylene.

Conventionally, propylene having a double bond forms a complex with silver ions, but it is known that propane does not form a complex with silver ions. By virtue of this chemical property, the solubility of propylene for an absorption liquid containing silver ions (for example, an aqueous solution of silver nitrate) under a certain condition is considerably larger than that of propane for the absorption liquid. The inventors of the present invention have conducted research on a method for obtaining high-purity propylene at a high recovery rate from a raw material gas containing propylene and propane by utilizing a difference in solubility between propylene and propane containing an absorption liquid containing silver ions. As a result, it has been found that the raw material gas is absorbed into the absorption liquid while being continuously operated, and the non-absorbed gas that is not absorbed by the absorption liquid is discharged (the first step), and the operation is carried out by stripping the dissolved gas with the absorption liquid to recover ( In the second step), propylene is obtained in high purity in the recovered gas. Further, it has been found that in the first step, high purity can be achieved by operating two operating temperature conditions and using a lower purity crude propylene raw material, thereby completing the present invention. In other words, in the present invention, when the second temperature is equal to or lower than the first temperature, it is possible to achieve high purity by using a crude propylene raw material having a low purity. In the absorption tower, propylene is preferentially absorbed, and in the stripping tower, since propylene has a lower boiling point than water, it becomes a gas state in which propylene which is higher in purity than the crude propylene raw material is preferentially boiled.

Preferably, the impurities include at least one selected from the group consisting of propane, oxygen, nitrogen, carbon dioxide, carbon monoxide, methane, ethane, and butane.

Preferably, the concentration of propylene in the above raw material is 96.84 mol% or more and less than 99.99 mol%.

Preferably, the above absorption liquid is an aqueous solution of silver nitrate.

Preferably, in the first step, the contact between the raw material and the absorbing liquid is performed by a countercurrent contact.

According to a second aspect of the present invention, an apparatus for purifying propylene from a raw material containing propylene and impurities is provided. The apparatus includes a first temperature and a first pressure, and the raw material is brought into contact with an absorption liquid containing silver ions, and propylene in the raw material is preferentially absorbed in the absorption liquid to absorb non-absorbed gas that is not absorbed by the absorption liquid. Extracting an absorption tower having a temperature adjustment function outside the tower; separating the mist contained in the non-absorbed gas derived from the absorption tower at a second temperature lower than the first temperature, and returning the liquid component to the absorption tower while discharging the gas And the above-mentioned absorption tower is a mist eliminator having an independent temperature adjustment function; at a third temperature and a second pressure, a stripping tower for recovering propylene by stripping the absorbing liquid of propylene; and absorbing the above-mentioned absorption a circulation means for circulating the liquid between the absorption tower and the stripping column, wherein the ratio of the non-absorbed gas to be discarded by the raw material is not absorbed by the absorption liquid in the absorption tower, and is adjusted to 1 In the range of up to 20 mol%, a high purity propylene can be obtained, and a purification apparatus for propylene is provided.

Preferably, the impurity includes at least one selected from the group consisting of propane, oxygen, nitrogen, carbon dioxide, carbon monoxide, methane, ethane, and butane.

Preferably, the propylene concentration in the above raw material is 96.84 mol% or more and less than 99.99 mol%.

According to a preferred embodiment of the second aspect of the present invention, the absorption tower includes a bubble column for introducing a gas introduction pipe for the raw material, and the bubble column is configured to introduce the circulated absorption liquid from an upper portion thereof. The gas introduction pipe is opened to the lower portion of the bubble column.

According to still another preferred embodiment of the second aspect of the present invention, the absorption tower includes a packed column for introducing a gas introduction pipe for the raw material, wherein the packed column is filled with a filler on an upper portion thereof and introduced into the upper portion. The circulating absorption liquid is configured such that the gas introduction pipe is opened below the filler.

The purification method according to the first aspect of the present invention can be efficiently carried out by using the propylene purification apparatus according to the second aspect of the present invention.

Other features and advantages of the present invention will become more apparent from the description of the appended claims.

Hereinafter, as a preferred embodiment of the present invention, a method of concentrating and purifying propylene from a material gas containing propylene and propane will be specifically described with reference to the drawings.

Fig. 1 is a schematic configuration diagram of a propylene purification apparatus of the present invention. The propylene purification equipment X is constructed by purifying crude propylene supplied from a gas cylinder Y. The propylene purification device X comprises an absorption tower 1, a stripper 2, a flow regulator 3, a demister 4 and 5, a flow control valve 6, a pump 7, a gas discharge port 8, a gas recovery port 9, and a connection of the elements. Piping.

The gas cylinder Y is used to supply crude propylene as a raw material gas to the propylene purification equipment X, and the crude propylene is sealed under high pressure conditions. The crude propylene contains, for example, propylene as a main component, and contains propane as an impurity. Further, as the impurity, not only propane but also at least one selected from the group consisting of oxygen, nitrogen, carbon dioxide, carbon monoxide, methane, ethane, and butane may be contained. The concentration of propylene contained in the above crude propylene raw material is preferably 96.84 mol% or more and less than 99.99 mol%. In addition, although the case where the source gas is supplied from the gas cylinder Y is shown in FIG. 1, the supply state of the material gas is not limited to the gas phase supply by the gas cylinder Y. For example, a gas obtained by supplying a liquefied gas from a vessel including a liquid phase supply line and vaporizing it using a vaporizer may be used as a material gas.

The absorption tower 1 has a tower main body 1A, a gas introduction pipe 1b, an absorption liquid discharge pipe 1c, and a gas discharge pipe 1d, and the raw material gas is brought into contact with the absorption liquid. The tower main body 1A is a sealed container, and contains an absorption liquid containing a silver ion solution therein. The absorption liquid is, for example, an aqueous silver nitrate solution prepared to have a predetermined concentration. The gas introduction pipe 1b has its end portion opened in the absorption liquid, for example, in the lower portion of the column main body 1A, and the raw material gas supplied from the gas cylinder Y is introduced into the column main body 1A. The open end of the gas introduction pipe 1b may include, for example, a single opening portion, or may include a plurality of openings for diffusing air. The absorption liquid discharge pipe 1c has its end opened in the absorption liquid in the lower portion of the column body 1A, and the absorption liquid in the absorption tower 1 is led out to the outside of the column. The gas discharge pipe 1d is connected to the upper portion of the column main body 1A, and the gas (non-absorbed gas) absorbed by the absorption liquid portion is led out of the tower.

As the absorption tower 1 having the above configuration, for example, a known bubble column, a packed column, a wet wall column, a spray tower, a washing column, a laminate column, or the like can be used. Fig. 1 shows a case where the absorption tower 1 (tower body 1A) is a bubble column. Further, the absorption tower 1 is provided with a temperature adjustment device (not shown) for maintaining the absorption liquid in the column main body 1A at a desired temperature. The temperature adjustment device is provided, for example, by providing a cover around the tower body 1A to circulate a temperature medium containing a gas or a liquid.

The stripper 2 has a column main body 2A, an absorption liquid introduction pipe 2b, an absorption liquid discharge pipe 2c, and a gas discharge pipe 2d, and strips the gas component absorbed by the absorption liquid in the absorption tower 1. The tower main body 2A is a sealed container, and a predetermined amount of the above-mentioned absorbing liquid can be accommodated in the inside. The absorption liquid introduction pipe 2b is opened at its end in the upper space in the tower main body 2A, and the absorption liquid led out from the absorption tower 1 is introduced into the tower main body 2A. Further, the absorption liquid introduction pipe 2b is connected to the absorption liquid discharge pipe 1c of the absorption tower 1 via the pipe L1 and the flow rate control valve 6.

The absorption liquid discharge pipe 2c is opened at the lower end of the absorption liquid in the lower portion of the column body 2A, and the absorption liquid in the stripper 2 is led out of the column. Further, the absorption liquid discharge pipe 2c is connected to the middle of the gas discharge pipe 1d of the absorption tower 1 via the pipe L2 and the pump 7. The pump 7 sends the absorption liquid in the gas tower 2 to the gas discharge pipe 1d. The absorption liquid discharge pipe 1c, the pipe L1, the flow rate control valve 6, the absorption liquid introduction pipe 2b, the absorption liquid discharge pipe 2c, the pipe L2, the pump 7, and the gas discharge pipe 1d constitute a circulation means of the absorption liquid. The gas discharge pipe 2d is connected to the upper portion of the stripper 2, and the stripping gas stripped by the absorption liquid is led out of the stripper 2. The stripping column 2 having the configuration of this embodiment is preferably a structure in which the absorption liquid can be stripped, and examples thereof include a conventional packed column, a washing column, and the like. Further, the stripping column 2 is provided with a temperature adjusting device (not shown) for maintaining the absorption liquid in the column main body 2A at a desired temperature.

The flow rate adjuster 3 regulates the flow rate of the raw material supplied from the gas cylinder Y to a predetermined flow rate.

The mist eliminator 4 is connected to the gas discharge pipe 1d of the absorption tower 1, and separates the mist contained in the non-absorbed gas which is led out through the gas discharge pipe 1d. The mist eliminator 4 is connected to a pipe L3 for guiding the gas passing through the demister 4 to the gas discharge port 8. The pipe L3 is provided with a back pressure valve 10 and a pressure gauge 11. The back pressure valve 10 regulates the opening so that the inside of the absorption tower 1 becomes a predetermined pressure. Further, the defogger 4 is provided with a temperature adjusting device (not shown) for maintaining the internal temperature at a desired temperature.

The mist eliminator 5 is connected to the gas discharge pipe 2d of the stripping column 2, and separates the mist contained in the stripping gas which is led out through the gas discharge pipe 2d. The mist eliminator 5 is connected to a pipe L4 for guiding the gas passing through the demister 5 to the gas recovery port 9. The pipe L4 is provided with a back pressure valve 12 and a pressure gauge 13. The back pressure valve 12 regulates the opening so that the inside of the stripper 2 becomes a predetermined pressure. Further, the defogger 5 is provided with a temperature adjusting device (not shown) for maintaining the inside temperature at a desired temperature.

When the propylene purification method of the present invention is carried out using the propylene purification equipment X having the above configuration, the gas is continuously supplied from the gas cylinder Y to the column main body 1A of the absorption tower 1 via the flow rate adjuster 3 and the gas introduction pipe 1b.

The material gas contains propylene as a main component and contains, for example, propane as an impurity, as described above. The propylene concentration of the material gas supplied from the gas cylinder Y is, for example, 96.84 mol% or more and less than 99.99 mol%. Further, the supply amount of the material gas to the absorption tower 1 is, for example, 1 to 100 dm ³ /s per 1 m ² of the column cross-sectional area, and is, for example, 40 to 4000 cm ³ /min according to the laboratory scale.

In the tower main body 1A of the absorption tower 1, a raw material gas is discharged from the end portion of the gas introduction pipe 1b, and the raw material gas is sequentially absorbed by the absorption liquid by being brought into contact with the absorption liquid. Here, since the solubility of propylene for an absorbing liquid (for example, an aqueous solution of silver nitrate) is considerably larger than the solubility of impurities such as propane, propylene in the material gas is preferentially absorbed by the absorbing liquid. Therefore, when the raw material gas is absorbed and the absorption liquid rises, the propylene concentration in the gas is lowered, and the impurity concentration (for example, the propane concentration) is increased.

On the other hand, in the absorption liquid in the column main body 1A, the absorption liquid which has absorbed the raw material gas in the absorption tower 1 flows out from the lower portion of the column main body 1A to the absorption tower 1 at a predetermined flow rate via the absorption-desiring discharge pipe 1c, The absorbing liquid of the stripped gas component in the stripping column 2 flows into the column from the upper portion of the column body 1A through the pump 7 and the gas outlet pipe 1d. Thereby, a downward flow occurs in the absorbing liquid (liquid bath) in the column body 1A. Therefore, the raw material gas discharged from the gas introduction pipe 1b comes into contact with the absorbing liquid in a countercurrent flow, and the non-absorbed gas which is not absorbed by the contact is blown off the upper space of the tower main body 1A. The non-absorbent gas system is sent to the mist eliminator 4 via the gas discharge pipe 1d, and the liquid component is separated and removed, and then discharged to the outside of the tower as an off gas through the pipe L3 and the gas discharge port 8. On the other hand, the liquid component separated by the defogger 4 drops into droplets passing through the gas discharge pipe 1d, and is returned to the absorption tower 1.

The temperature adjusting device provided in the demister 4 and the absorption tower 1 (tower body 1A) can be set to a different temperature, and the temperature difference between the demister 4 and the tower body 1A can be imparted.

Regarding the absorption liquid (for example, an aqueous silver nitrate solution) in the absorption tower 1, it is preferable that the absorption amount of propylene per unit volume per unit time increases as the concentration increases. From a practical viewpoint, the concentration of the aqueous silver nitrate solution is, for example, in the range of 1 to 6 mol/dm ³ , more preferably in the range of 3 to 5 mol/dm ³ . Regarding the temperature of the aqueous silver nitrate solution, the absorption amount of propylene is increased at a low temperature, and is, for example, in the range of 0 to 60 ° C, more preferably 0 to 50 ° C. It is preferable that the internal pressure of the column main body 1A is a high pressure in a certain range to increase the absorption amount of propylene. From the practical point of view, the internal pressure of the column body 1A is, for example, 0.1 to 0.8 MPa (G) (G is the gauge pressure shown). Further, the internal temperature of the demister 4 is desirably equal to or lower than the internal temperature of the tower body 1A.

In this manner, in the absorption tower 1, the raw material gas continuously supplied is brought into contact with the absorption liquid to preferentially absorb the propylene in the material gas to the absorption liquid, and the non-absorption gas is discharged to the outside of the column.

The absorption liquid which absorbs the raw material gas in the absorption tower 1 is introduced by the absorption liquid discharge pipe 1c, the pipe L1, the flow rate control valve 6, and the absorption liquid by the pressure difference between the internal pressure of the absorption tower 1 and the internal pressure of the stripper 2 The tube 2b flows into the column body 2A of the stripper 2. Further, when the pressure difference is small, the pump may be used to transfer the absorbing liquid. At this time, the inflow amount of the absorbing liquid to the column body 2A is adjusted by the flow rate adjusting valve 6, for example, the cross-sectional area of the column is 0.1 to 10 dm ³ /s per 1 m ² , and may be, for example, 5 to 500 cm on a laboratory scale. ³ / min.

In the column body 2A of the stripper 2, the gas component in the absorption liquid is stripped. From the viewpoint of efficiently stripping the gas component, the internal temperature of the column body 2A is preferably higher than that of the absorption tower 1, and the internal pressure is preferably lower than that of the absorption tower 1. The temperature of the absorbing liquid of the column body 2A is, for example, preferably 10 to 70 ° C, more preferably 20 to 70 ° C. The internal pressure of the column body 2A is, for example, preferably -0.09 to 0.3 MPa (G), and the pressure is 0 to 0.3 MPa (G). Here, the stripping gas which is stripped by the absorbing liquid is sent to the demister 5 via the gas discharge pipe 2d, and the liquid component is removed, and then recovered as a purified gas through the pipe L4 and the gas recovery port 9. Further, the liquid component separated by the mist eliminator 5 is dropped by the gas discharge pipe 2d, and is returned to the stripper 2 .

The stripped absorbent of the gas component is sent to the gas outlet pipe 1d through the absorption liquid discharge pipe 2c by the pump 7, and then falls into the column body 1A of the absorption tower 1. At this time, the flow rate of the absorption liquid sent out by the pump 7 is the same as the flow rate of the absorption liquid which flows into the stripper 2 through the flow rate control valve 6 by the absorption tower 1. Thereby, the absorption liquid in the absorption tower 1 and the absorption liquid in the stripping tower 2 are mutually balanced and circulated (circulation step).

In this way, in the stripping column 2, the gas component of the absorbing liquid continuously flowing at a predetermined flow rate is stripped, and the stripping gas is recovered outside the column. Since the stripping gas is stripped from the absorbing liquid in which the propylene in the raw material gas is preferentially absorbed, the propylene concentration is higher than the raw material gas.

By the above means, for example, a crude propylene gas (raw material gas) containing, for example, propane as an impurity can be purified to obtain high-purity propylene.

The solubility of propylene in an aqueous solution of silver nitrate is disclosed in detail in the paper (Solubility of Propylene in Aqueous Silver Nitrate, IH Cho, DL Cho, HK Yasuda, and TR Marrero, J. Chem. Eng. Data 1995, 40, 102-106). ). In this document, the solubility of propane in an aqueous solution of silver nitrate is also shown to be small. According to the data disclosed in this document, in order to obtain high-purity propylene (purity of 99.99% or more), the recovery rate of propylene is theoretically lowered as shown below.

Based on the data shown in the above literature, in a closed system, the pressure range is 0 to 0.6 MPa (G), and the temperature range is 10 to 40 ° C. The gas-liquid equilibrium constant for propylene and propane for an aqueous solution of silver nitrate is about 150. . That is, (gas phase propane concentration / gas phase propylene concentration) / (liquid phase propane concentration / liquid phase propylene concentration) = 150. The simulation of the propylene gas purification using this gas-liquid equilibrium constant is as follows.

The crude propylene gas containing 1 mol% of propane containing impurities as an impurity is absorbed in an aqueous solution of silver nitrate, and the absorbed gas component is stripped to obtain high-purity propylene. First, when it is estimated that 95% of propylene contained in the material gas is absorbed by the silver nitrate aqueous solution, propane / (propylene + propane) in the liquid phase is 0.11 mol%, which is about 1 mol% of the initial propane concentration of 1 mol%. One. At this time, the propane concentration in the gas phase became 15.21 mol%, and the propane of the impurity was concentrated. However, the propylene concentration in the liquid phase is 99.89 mol%, and it is difficult to obtain high-purity propylene having a purity of 99.99 mol% or more as a target under such conditions.

Therefore, assuming that 30 mol% of propylene contained in the material gas is absorbed by the aqueous silver nitrate solution and the same calculation is performed using the gas-liquid equilibrium constant described above, the propylene concentration in the liquid phase is 99.99 mol%, and the propylene concentration in the gas phase is obtained. At 98.58 mol%, the purity of propylene in the liquid phase at this stage reaches the target value. That is, only 30 mol% can be recovered from the crude propylene gas.

As an application of this method, an attempt was made to actually purify in batch mode. A crude propylene gas having a purity of 99 mol% containing propane of 1 mol% in a 5 mol/dm ³ silver nitrate aqueous solution was dissolved at a temperature of 25 ° C and a pressure of 0.6 MPa (G). The volume ratio of the gas phase portion to the liquid phase portion at this time was 0.56. Next, first, the pressure is lowered from 0.6 MPa (G) to 0.2 MP (G), and the gas component is slowly stripped by the silver nitrate aqueous solution, and then the temperature of the absorption tower is heated from 25 ° C to a temperature increase rate of 0.5 ° C / min. The residual gas component is regenerated at 40 °C. The stripping gas system initially contains propane at a high concentration in the stripping gas system, but the propane concentration becomes lower as the stripping progresses. When about 35 mol% of the absorbed propylene gas was stripped, the propylene purity of the stripping gas became 99.99 mol%. From this, it is understood that in the batch formula, in order to obtain a high-purity propylene gas, the recovery rate of the propylene gas has to be lowered, and the purity and the recovery ratio are set to be in a substitution relationship.

In this case, Patent Document 1 discloses that in the case where the absorption liquid (for example, an aqueous silver nitrate solution) of the present embodiment is continuously subjected to continuous absorption of a raw material gas (crude propylene gas) and stripping, the temperature in the column is arranged. High-purity propylene can be obtained at a high recovery rate under the conditions of pressure, raw material gas supply state, and absorption liquid state (concentration, usage amount, circulation flow rate).

According to Patent Document 1, the ratio of the amount of non-absorbed gas to be discarded by the absorption liquid in the absorption tower 1 is not absorbed, and depending on the purity of the propylene gas of the material gas and the desired purity of propylene after purification, The raw material gas is adjusted, for example, in the range of 1 to 20 mol%, and high purity propylene having a purity of 99.99 mol% can be obtained. The adjustment of the amount of non-absorbed gas can be realized, for example, by adjusting the supply amount of the material gas, the concentration of the absorption liquid, the residence time in the column main body 1A of the absorption liquid, and the temperature and pressure in the column main body 1A. When the concentration of the impurity propane in the material gas is high, the amount of the non-absorbed gas is large. However, when the crude propylene gas having a purity of 99.0 mol% (propane concentration: 1.0 mol%) is purified, the non-absorbed gas amount may be 5 mol% obtained high purity propylene having a purity of 99.99 mol%. On the other hand, when the concentration of the impurity propane in the material gas is low, for example, when the crude propylene gas having a purity of 99.9 mol% (propane concentration: 0.1 mol%) is purified, the ratio of the non-absorbed gas amount is suppressed to 1 mol. At a level of %, high purity propylene having a purity of 99.99 mol% is still not obtained. In this manner, in the case of the continuous type, even if the amount of the non-absorbed gas to be discarded is reduced and the recovery rate is increased, high-purity propylene (purity: 99.99 mol%) cannot be obtained. This result cannot be inferred from the theoretical calculation based on the gas-liquid equilibrium constant described above. Although the reason for obtaining the above effects is not clear, for example, attention is paid to the state of the material gas in which the absorption liquid is absorbed, and the gas and liquid are in a static equilibrium state with respect to the batch type, and the gas is continuously used in the continuous type. The liquid contact is related to the dynamic equilibrium state. Further, Patent Document 1 discloses a discussion in which a propylene and a silver ion are formed in a wrong form as compared with a rate at which a propane gas is dissolved in an absorbing liquid, and a speed at which a propylene gas is dissolved in an absorbing liquid is fast, in the case of a continuous type. The propylene gas is preferentially absorbed, and the propylene gas having a high purity in the stripping column may be a factor for obtaining the above effects.

In Patent Document 1, the concentration of propylene in the material gas is 98 to 99.5 mol%. However, purification of a raw material propylene gas having a lower purity into a field of an electronic material such as a semiconductor can be difficult to purify using a degree of propylene purity. In other words, high purity purification of the crude propylene raw material containing 0.5 to 2.0 mol% of impurities is difficult.

In Patent Document 1, in order to adjust only the temperature of the absorption tower to a predetermined value, in the absorption tower connected to the demister, since the evaporated absorption liquid releases heat during condensation, the temperature inside the demister is more than the temperature inside the absorption tower. High tendency. On the other hand, in the present invention, it has been found that the temperature control device provided in the improved demister 4 and the tower main body 1A can be set to different temperatures, and the internal temperature of the demister 4 is set as the inside of the tower body 1A. Below the temperature, even if the propylene concentration of the crude propylene raw material is in a range other than the range disclosed in Patent Document 1 (98 to 99.5 mol%) (the propylene concentration is 96.84 mol% or more and less than 99.99 mol%), as a purification The gas can obtain high-purity propylene having a purity of 99.98 mol% or more at a high recovery rate. Further, it has been found that the impurities are not only propane, but may be purified to a desired propylene purity even when at least one of oxygen, nitrogen, carbon dioxide, carbon monoxide, methane, ethane, and butane is contained. In particular, even if the propylene concentration in the crude propylene raw material is low purity (96.84 mol% or more and less than 98 mol%), the purity can be higher than a predetermined concentration, and a low-priced raw material containing a relatively large amount of impurities can be used. It is required to be used in the field of electronic materials such as high-purity semiconductors, and it is expected to be utilized in a wide range of fields.

The embodiments of the present invention have been described above, and the scope of the present invention is not limited to the above embodiments. The propylene purification apparatus of the present invention and the specific constitution of the propylene purification method of the present invention can be variously modified without departing from the scope of the invention.

Regarding the method of contacting the material gas in the absorption tower 1 with the absorption liquid, it is not necessary to contact the opposite flow. For example, the absorption liquid discharge pipe 1c may be open to the upper portion of the liquid bath of the absorption liquid. In this case, the portion where the absorption liquid and the material gas are in contact with each other in the countercurrent flow is only in a higher range than the end portion of the absorption liquid discharge pipe 1c. In this case, high purity propylene can be obtained with high recovery.

In the above embodiment, the case where the absorption tower 1 (tower body 1A) is a bubble column is exemplified, and another configuration may be employed as the absorption tower (tower body). Fig. 2 shows a schematic configuration of a case where an absorption tower (tower body) is a packed column. Also shown in the tower main body 1B of Fig. 2, the upper portion of the inside of the tower is filled with the filler F, and the absorption liquid tower sent from the vapor tower 2 is inserted into the piping L2 for the inside of the tower, and is opened to the upper portion of the filler F. The end of the gas introduction pipe 1b is opened to the central space inside the tower. The material gas is discharged from the end of the gas introduction pipe 1b in the column main body 1B, and the material gas and the absorption liquid introduced through the pipe L2 are in an effective counterflow contact with the surface of the filler, and are sequentially absorbed by the absorption liquid. [Examples]

Next, the usefulness of the present invention will be described by way of examples.

[Example 1] In the present example, propylene purification equipment X shown in Fig. 1 was used, and crude propylene gas was used as a raw material gas, and propylene was purified from a raw material gas.

In the present embodiment, as the tower main body 1A of the absorption tower 1 (bubble tower) and the tower main body 2A of the stripping tower 2, a cylindrical tube made of stainless steel (inner diameter 56.6 mm, height 150 mm: volume 375 cm ³ ) was used. As the absorption liquid, the body accommodated within the column an aqueous solution of silver nitrate 1A 3mol / dm ³ in 225cm ³ (depth of 90mm), the housing of the aqueous silver nitrate solution with a concentration of 225cm ³ (90mm depth) within the column body 2A. As the conditions of the absorption tower 1, the internal pressure of the tower main body 1A was 0.3 MPa (G), the internal temperature of the tower main body 1A was 50 ° C, and the internal temperature of the demister 4 was adjusted to 5 ° C. The conditions of the stripper 2 were adjusted such that the internal pressure of the column main body 2A was 0.1 MPa (G) and the internal temperature was 40 °C. The aqueous silver nitrate solution accommodated in the column bodies 1A and 2A was circulated between the column bodies 1A and 2A at a flow rate of 20 cm ³ /min. The raw material gas was supplied to the absorption tower 1 using a propylene concentration of 96.84 mol%, a propane concentration of 3.07 mol%, a methane concentration of 660 mol ppm, an ethane concentration of 220 mol ppm, and a butane concentration of 20 m. Ear ppm. The supply amount of the material gas was a flow rate of 196 cm ³ /min.

The results of analyzing the purified gas from the stripping column 2 and the non-absorbed gas from the absorption tower 1 during the steady operation are shown in the table of Fig. 3. In the present embodiment, the purified gas from the stripping column 2 is a high-purity propylene gas having a purity of 99.99 mol% (propane concentration: 72 mol ppm, methane concentration: 1.0 mol ppm, ethane concentration not detected, butane concentration). Not detected) can be obtained at 166.6 cm ³ /min with a recovery of 85 mol%. Further, the non-absorbent gas from the absorption tower 1 was discharged at 29.4 cm ³ /min, and the discharge rate was 15 mol%. Further, the measured concentration was "not detected", which means that the lower limit of the measurement was not reached (less than 0.1 mol ppm), and the same applies hereinafter.

From the results of Example 1, the purification ability of the impurity propane = (propane concentration in the raw material propylene) / (propane concentration in the purified propylene) = 3.07 mol% / 72 mol ppm = 426.4. If the impurity in propylene is only a raw material of propane, for example, a crude propylene raw material containing a diene concentration of 4.26 mol% as an impurity, when the purification ability of the impurity propane of the condition of Example 1 is calculated, it is presumed that purification can be obtained. The propane concentration in the gas was 99.9 mol ppm, and the purity was 99.99%. That is, in the present invention, the separation of propane in the crude propylene raw material may be up to about 4.26 mol% of the raw material concentration. That is, since the purity of the propylene is 99.99 mol%, the allowable range of impurities is less than 100 mol ppm, the propylene having a purity of 99.99% in the present invention can be obtained, and the separation of propane from the crude propylene raw material can be adapted. The propane concentration in the crude propylene feedstock is from 100 mole ppm to 4.26 mole percent.

[Example 2] In the present example, propylene was purified from a raw material gas under the conditions different from those in Example 1 using the same propylene purification equipment as in Example 1.

In the present embodiment, as the absorbing liquid, the column main body 1A accommodates 225 cm ³ (water depth: 90 mm) of a 3 mol/dm ³ silver nitrate aqueous solution, and the column main body 2A contains 225 cm ³ (water depth: 90 mm) of a silver nitrate aqueous solution having the same concentration. As the conditions of the absorption tower 1, the internal pressure of the column main body 1A was 0.3 MPa (G), the internal temperature of the column main body 1A was 25 ° C, and the internal temperature of the demister 4 was adjusted to 25 ° C. The conditions of the stripper 2 were adjusted such that the internal pressure of the column main body 2A was 0.1 MPa (G) and the internal temperature was 40 °C. The aqueous silver nitrate solution accommodated in the column bodies 1A and 2A was circulated between the column bodies 1A and 2A at a flow rate of 20 cm ³ /min. The raw material gas was supplied to the absorption tower 1 using a propylene concentration of 99.55 mol%, a propane concentration of 0.15 mol%, a methane concentration of 75 mol ppm, an ethane concentration of 40 mol ppm, and a nitrogen concentration of 2800 m. P, an oxygen concentration of 30 mole ppm, a carbon dioxide concentration of 0.2 mole ppm, and a carbon monoxide concentration of 0.1 mole ppm. The supply amount of the material gas was a flow rate of 500 cm ³ /min.

The results of analyzing the purified gas from the stripping column 2 and the non-absorbed gas from the absorption tower 1 during the steady operation are shown in the table of Fig. 3. In the present embodiment, the purified gas from the stripping column 2 is a high-purity propylene gas having a purity of 99.99 mol% (propane concentration of 10 mol ppm, methane concentration is not detected, ethane concentration is not detected, and nitrogen concentration is 1.0 mol). Ear ppm, oxygen concentration 0.2 mol ppm, carbon dioxide concentration 0.1 mol ppm, carbon monoxide concentration not detected) can be obtained at 425 cm ³ /min with a recovery of 85 mol%. Further, the absorption tower 1 was discharged at a rate of 75 cm ³ /min for a non-absorbed gas, and the discharge rate was 15 mol%.

[Example 3] In the present example, propylene was purified from the raw material gas under the conditions different from those in Example 1 using the same propylene purification equipment as in Example 1.

In the present embodiment, as the absorbing liquid, the column main body 1A accommodates 225 cm ³ (water depth: 90 mm) of a 3 mol/dm ³ silver nitrate aqueous solution, and the column main body 2A contains 225 cm ³ (water depth: 90 mm) of a silver nitrate aqueous solution having the same concentration. As the conditions of the absorption tower 1, the internal pressure of the column main body 1A was 0.3 MPa (G), the internal temperature of the column main body 1A was 25 ° C, and the internal temperature of the demister 4 was adjusted to 25 ° C. The conditions of the stripper 2 were adjusted such that the internal pressure of the column main body 2A was 0.1 MPa (G) and the internal temperature was 40 °C. The aqueous silver nitrate solution accommodated in the column bodies 1A and 2A was circulated between the column bodies 1A and 2A at a flow rate of 20 cm ³ /min. The raw material gas is supplied to the absorption tower 1 using a propylene concentration of 99.65 mol%, a propane concentration of 0.1 mol%, a methane concentration of 1 mol ppm, an ethane concentration of 1 mol ppm, and a butane concentration of 20 m. The ear ppm, the nitrogen concentration was 2400 mol ppm, the oxygen concentration was 50 mol ppm, the carbon dioxide concentration was 0.2 mol ppm, and the carbon monoxide concentration was 0.1 mol ppm. The supply amount of the material gas was a flow rate of 450 cm ³ /min.

The results of analyzing the purified gas from the stripping column 2 and the non-absorbed gas from the absorption tower 1 during the steady operation are shown in the table of Fig. 3. In the present embodiment, the purified gas from the stripping column 2 is a high-purity propylene gas having a purity of 99.98 mol% (propane concentration of 6 mol ppm, methane concentration is not detected, ethane concentration is not detected, butane concentration is not The nitrogen concentration was 1.8 mol ppm, the oxygen concentration was 0.7 mol ppm, the carbon dioxide concentration was 0.1 mol ppm, and the carbon monoxide concentration was not detected. It was 382.4 cm ³ /min, and the recovery was 85 mol%. Further, the non-absorbent gas from the absorption tower 1 was discharged at 67.6 cm ³ /min, and the discharge rate was 15 mol%.

[Example 4] In the present example, propylene was purified from the raw material gas under the conditions different from those in Example 1 using the same propylene purification equipment as in Example 1.

In the present embodiment, as the absorbent, the column main body 1A contains 225 cm ^{3 of a} silver nitrate aqueous solution of 3 mol/dm ³ (water depth: 90 mm), and the column main body 2A contains 225 cm ³ (water depth: 90 mm) of a silver nitrate aqueous solution having the same concentration. The conditions of the absorption tower 1 were adjusted such that the internal pressure of the column main body 1A was 0.3 MPa (G), the internal temperature of the column main body 1A was 50 ° C, and the internal temperature of the demister 4 was 20 ° C. The conditions of the stripper 2 were adjusted such that the internal pressure of the column main body 2A was 0.1 MPa (G) and the internal temperature was 40 °C. The aqueous silver nitrate solution accommodated in the column bodies 1A and 2A was circulated between the column bodies 1A and 2A at a flow rate of 20 cm ³ /min. The raw material gas was supplied to the absorption tower 1 using a propylene concentration of 96.84 mol%, a propane concentration of 3.07 mol%, a methane concentration of 660 mol ppm, an ethane concentration of 220 mol ppm, and a butane concentration of 20 m. Ear ppm. The supply amount of the material gas was a flow rate of 196 cm ³ /min.

The results of analyzing the purified gas from the stripping column 2 and the non-absorbed gas from the absorption tower 1 during the steady operation are shown in the table of Fig. 3. In the present embodiment, the purified gas from the stripping column 2 is a high-purity propylene gas having a purity of 99.98 mol% (propane concentration: 148 mol ppm, methane concentration: 1.4 mol ppm, ethane concentration not detected, butane concentration) Not detected) can be obtained at 166.6 cm ³ /min with a recovery of 85 mol%. Further, the non-absorbent gas from the absorption tower 1 was discharged at 29.4 cm ³ /min, and the discharge rate was 15 mol%.

[Example 5] In the present example, propylene was purified from the raw material gas under the conditions different from those in Example 1 using the same propylene purification equipment as in Example 1.

In the present embodiment, as the absorbing liquid, the column main body 1A accommodates 225 cm ³ (water depth: 90 mm) of a 3 mol/dm ³ silver nitrate aqueous solution, and the column main body 2A contains 225 cm ³ (water depth: 90 mm) of a silver nitrate aqueous solution having the same concentration. As the conditions of the absorption tower 1, the internal pressure of the tower main body 1A was 0.3 MPa (G), the internal temperature of the tower main body 1A was 50 ° C, and the internal temperature of the demister 4 was adjusted to 5 ° C. The conditions of the stripper 2 were adjusted such that the internal pressure of the column main body 2A was 0.1 MPa (G) and the internal temperature was 40 °C. The aqueous silver nitrate solution accommodated in the column bodies 1A and 2A was circulated between the column bodies 1A and 2A at a flow rate of 20 cm ³ /min. The raw material gas was supplied to the absorption tower 1 using a propylene concentration of 96.91 mol% and a propane concentration of 3.09 mol%. The supply amount of the material gas was a flow rate of 200 cm ³ /min.

The results of analyzing the purified gas from the stripping column 2 and the non-absorbed gas from the absorption tower 1 during the steady operation are shown in the table of Fig. 3. In the present embodiment, as the purified gas from the stripping column 2, a high-purity propylene gas (propane concentration: 75 mol ppm) having a purity of 99.99 mol% was obtained at 170 cm ³ /min, and the recovery was 85 mol%. Further, the absorption tower 1 was discharged as a non-absorbent gas at 30 cm ³ /min, and the discharge rate was 15 mol%.

[Example 6] In the present example, propylene was purified from the raw material gas under the conditions different from those in Example 1 using the same propylene purification equipment as in Example 1.

In the present embodiment, as the absorbing liquid, the column main body 1A accommodates 225 cm ³ (water depth: 90 mm) of a 3 mol/dm ³ silver nitrate aqueous solution, and the column main body 2A contains 225 cm ³ (water depth: 90 mm) of a silver nitrate aqueous solution having the same concentration. The conditions of the absorption tower 1 were adjusted such that the internal pressure of the column main body 1A was 0.3 MPa (G), the internal temperature of the column main body 1A was 50 ° C, and the internal temperature of the demister 4 was 50 ° C. The conditions of the stripper 2 were adjusted such that the internal pressure of the column main body 2A was 0.1 MPa (G) and the internal temperature was 40 °C. The aqueous silver nitrate solution accommodated in the column bodies 1A and 2A was circulated between the column bodies 1A and 2A at a flow rate of 20 cm ³ /min. The raw material gas was supplied to the absorption tower 1 using a propylene concentration of 96.85 mol%, a propane concentration of 3.09 mol%, a methane concentration of 380 mol ppm, an ethane concentration of 200 mol ppm, and a butane concentration of 20 m. Ear ppm. The supply amount of the material gas was a flow rate of 517 cm ³ /min.

The results of analyzing the purified gas from the stripping column 2 and the non-absorbed gas from the absorption tower 1 during the steady operation are shown in the table of Fig. 3. In the present embodiment, the purified gas from the stripping column 2 is a high-purity propylene gas having a purity of 99.98 mol% (propane concentration: 220 mol ppm, methane concentration: 2.0 mol ppm, ethane concentration not detected, butane concentration) Not detected) can be obtained at 439.4 cm ³ /min with a recovery of 85 mol%. Further, the absorption tower 1 was discharged as a non-absorbent gas at 77.6 cm ³ /min, and the discharge rate was 15 mol%.

X‧‧‧Propylene purification equipment

Y‧‧‧ gas cylinder

1‧‧‧ absorption tower

1A‧‧‧ Tower body (bubble tower)

1B‧‧‧ Tower body (filled tower)

1b‧‧‧ gas introduction tube

1c, 2c‧‧ ‧ absorption fluid outlet tube

1d, 2d‧‧‧ gas outlet tube

2‧‧‧Stripper

2A‧‧‧ Tower Body

2b‧‧‧absorbing liquid introduction tube

3‧‧‧Flow Regulator

4, 5‧‧‧ defogger

6‧‧‧Flow control valve

7‧‧‧ pump

8‧‧‧ gas discharge

9‧‧‧ gas recovery port

10,12‧‧‧Back pressure valve

11, 13‧‧‧ pressure gauge

F‧‧‧Filling

L1, L2, L3, L4‧‧‧ piping

Fig. 1 is a schematic configuration diagram of a propylene gas purification apparatus according to the present invention. Fig. 2 is a schematic configuration diagram of an absorption tower according to the present invention. Fig. 3 is a table showing a purification example of propylene.

Claims (10)

A method for purifying propylene, which is a method for purifying propylene from a raw material containing propylene and impurities, the method comprising: forming the raw material and silver at a first temperature and a first pressure in an absorption tower having a temperature adjustment function When the absorbing liquid of the ion is contacted, the propylene in the raw material is preferentially absorbed in the absorbing liquid, and the defrosting device having a temperature adjustment function independent of the absorption tower is discharged at the second temperature below the first temperature. The first step of the non-absorbed gas absorbed by the absorption liquid, and the second step of recovering the propylene from the absorption liquid of the first step in the stripping column at the third temperature and the second pressure And circulate the absorption liquid between the absorption tower and the stripper, and simultaneously perform the first step and the second step simultaneously, wherein in the first step, the raw material is not absorbed by the absorption liquid The ratio of the non-absorbed gas which is absorbed and blown off is adjusted to a range of 1 to 20 mol%, and high-purity propylene can be obtained. The method for purifying propylene according to the first aspect of the invention, wherein the impurity comprises at least one selected from the group consisting of propane, oxygen, nitrogen, carbon dioxide, carbon monoxide, methane, ethane, and butane. The method for purifying propylene according to claim 1 or 2, wherein the concentration of propylene in the raw material is 96.84 mol% or more and less than 99.99 mol%. A method for purifying propylene according to the first aspect of the invention, wherein the absorbing liquid is an aqueous solution of silver nitrate. The method for purifying propylene according to any one of claims 1 to 4, wherein the contacting of the raw material in the first step with the absorbing liquid is carried out via a countercurrent contact. A propylene purification apparatus for purifying propylene from a raw material containing propylene and impurities, the apparatus comprising: an absorption tower, wherein the raw material is contacted with an absorption liquid containing silver ions at a first temperature and a first pressure; The propylene in the raw material is preferentially absorbed in the absorbing liquid, and the non-absorbent gas not absorbed by the absorbing liquid is led out to the outside of the column to have a temperature regulating function; and the defogger is at a second temperature below the first temperature, Separating the mist contained in the non-absorbed gas derived from the absorption tower, returning the liquid component to the absorption tower cake and discharging the gas, and having a temperature adjustment function independent of the absorption tower; the stripping tower at the third temperature and the 2 pressure, which is obtained by stripping propylene by absorption of the absorbing liquid of propylene; and recycling means for circulating the absorption liquid between the absorption tower and the stripping tower, wherein the absorption tower is not in the raw material The ratio of the non-absorbed gas which is absorbed by the absorption liquid and blown off and discarded is adjusted to a range of 1 to 20 mol%, and a high-purity propylene can be obtained. The propylene purification apparatus according to claim 6, wherein the impurities include at least one selected from the group consisting of propane, oxygen, nitrogen, carbon dioxide, carbon monoxide, methane, ethane, and butane. The propylene purification apparatus according to claim 6, wherein the concentration of propylene in the raw material is 96.84 mol% or more and less than 99.99 mol%. The propylene purification apparatus according to any one of claims 6 to 8, wherein the absorption tower includes a bubble column for introducing a gas introduction pipe of the raw material, and the bubble column is introduced into the cycle through the upper portion thereof. The absorbing liquid is configured such that the gas introduction pipe is opened at a lower portion of the bubble column. The propylene purification apparatus according to any one of claims 6 to 8, wherein the absorption tower includes a packed column for introducing a gas introduction pipe of the raw material, the packed tower is filled with a filler on an upper portion thereof. At the same time, the circulated absorption liquid is introduced into the upper portion, and the gas introduction pipe is opened below the filler.