JP6965199B2 - Gas purification equipment and gas purification method - Google Patents

Description

The present invention relates to a gas purification apparatus and a gas purification method.

In the production of industrial gas, a pressure fluctuation adsorption type device (PSA device) is known as a device for purifying a raw material gas containing a component to be removed to obtain a product gas. In the PSA apparatus, the raw material gas is purified in an adsorption tower filled with an adsorbent (Patent Document 1).

When each component of a mixed gas containing a plurality of gas components is separated and purified, it is common to keep the temperature of the adsorption tower at a temperature suitable for adsorption according to the type of adsorbent.
Patent Document 1 discloses a method for separating oxygen and nitrogen by a pressure swing adsorption method (PSA) using an adsorption tower filled with a heat storage material. In the separation method described in Patent Document 1, the temperature inside the adsorption tower is maintained by bringing the gas into contact with the heat storage material to recover the heat.

Japanese Unexamined Patent Publication No. 2010-12567

However, in the separation method described in Patent Document 1, since the heat storage material is filled in the adsorption tower, the filling amount of the adsorbent in the adsorption tower is limited by the filling amount of the heat storage material. Therefore, as compared with the case where only the adsorbent is filled in the adsorption tower, the amount of the adsorbent filled in the adsorption tower described in Patent Document 1 is reduced, and the purity of the product gas is lowered.

On the other hand, a method of keeping the temperature of the adsorbent at a temperature suitable for adsorption is also envisioned by heating the adsorption tower from the outside of the adsorption tower without filling the heat storage material. However, when the adsorption tower is heated from the outside, heat energy is further required for heating, which may increase the manufacturing cost. Further, when the adsorption tower is heated from the outside, it is difficult to uniformly heat the inside of the adsorption tower, it is difficult to effectively maintain the temperature of the adsorbent, and the yield and purity of the product gas may decrease. ..

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a gas purification apparatus capable of purifying a product gas with high purity and high yield at low cost.

In order to solve the above problems, the present invention has the following configurations.
[1] A gas purification device that purifies a product gas from a raw material gas containing a first gas and a second gas by a pressure fluctuation adsorption method, and is a gas other than the first gas and the second gas. Two or more first adsorption towers having a first adsorbent for adsorbing the second gas, two or more second adsorption towers having a second adsorbent for adsorbing the second gas, and the first adsorbent. A connection line that connects the secondary side of the suction tower 1 and the primary side of the second suction tower and through which the first gas and the second gas flow, and the secondary side of each of the second suction towers. A first lead-out line connected to the side and through which the first gas flows, a second lead-out line connected to the primary side of each of the second adsorption towers and through which the second gas flows, and the second lead-out line. A suction means for desorbing the second gas from the second adsorbent, which is provided in the lead-out line of the above, and a branch from the second lead-out line, which is connected to the secondary side of each of the second adsorption towers. Gas purification comprising a heat recovery line and a heat exchanger that exchanges heat between the second gas flowing through the heat recovery line and the first gas flowing through the first lead-out line. Device.
[2] Further provided with a regeneration line connected to the secondary side of the first adsorption tower and through which a regeneration gas for regenerating the first adsorbent flows, the regeneration line and the first lead-out line are connected. The gas purification device of [1].
[3] A pressure fluctuation adsorption type gas purification method using the gas purification apparatus of [1] or [2], wherein a gas other than the first gas and the second gas is added to the first adsorbent. It is adsorbed, the first gas and the second gas are supplied from the first adsorption tower b to the second adsorption tower b, and the second adsorbent b contained in the second adsorption tower b is said to have the first gas. After adsorbing the gas of 2, the second gas is desorbed from the second adsorbent b, and the second gas is introduced into the heat recovery line via the second lead-out line. A gas purification method in which the second gas flowing through the heat recovery line is heated by the heat exchanger, and the second gas is introduced from the heat recovery line into the second adsorption tower b.
[4] When the second gas is heated by the heat exchanger, the first gas and the second gas are supplied to the second adsorption tower a different from the second adsorption tower b, and the second gas is supplied. The second gas is adsorbed on the second adsorbent a contained in the second adsorption tower a, and the second gas is adsorbed.
The gas purification method according to [3], wherein the first gas is led out from the second adsorption tower a to the first lead-out line.

According to the present invention, the product gas can be purified with high purity and high yield at low cost.

It is a schematic diagram which shows an example of the structure of the gas purification apparatus which concerns on 1st Embodiment which is one Embodiment to which this invention is applied. It is a schematic diagram which shows an example of the structure of the gas purification apparatus which concerns on the technology related to the gas purification apparatus of FIG.

The meanings of the following terms in the present specification are as follows.
"PSA" is an abbreviation for Pressure Swing Adsorption. In the present specification, the pressure fluctuation adsorption method is referred to as "PSA method", and the device for purifying gas by the PSA method is referred to as "PSA device".
"Regeneration" of the adsorbent means returning the adsorbent to which the component to be removed has been adsorbed to a state in which the component to be removed can be adsorbed again.
The “regenerated gas” means a gas supplied to the adsorption tower having the adsorbent to be regenerated in order to return the adsorbent to a state in which the component to be removed can be adsorbed again.
The "recycled exhaust gas" is a gas discharged from an adsorption tower having an adsorbent to be regenerated, and means a gas used for regenerating the adsorbent.

Hereinafter, an embodiment to which the present invention is applied will be described in detail with reference to the drawings. In the drawings used in the following description, in order to make the features easy to understand, the featured portions may be enlarged for convenience, and the dimensional ratios and the like of each component are not always the same as the actual ones.

<Gas purification device>
The gas purification device of the present embodiment is a device that purifies a product gas from a raw material gas containing a first gas, a second gas, and a component to be removed.
The first gas, the second gas, and the components to be removed are not particularly limited. Specific examples of the first gas and the second gas include hydrocarbons such as ethane, ethylene, propane, propene, butane, and butene. Examples of the components to be removed include nitrogen, oxygen, argon, water vapor, methane, carbon monoxide, carbon dioxide and the like.

As the combination of the first gas and the second gas, at least two or more kinds can be selected from the above-mentioned specific examples. The effect of the present invention can also be obtained by selecting a combination of compounds having similar chemical or physical properties from among these. Examples of the combination of compounds having similar chemical or physical properties include a combination of ethane and ethylene, a combination of propane and propene, a combination of butane and butene, and the like.
In the following embodiment, a case where the raw material gas contains propane (first gas) and propene (second gas) and carbon dioxide as a component to be removed will be described as an example.

The gas purification device of this embodiment is a PSA device. Therefore, in the following embodiments, the depressurization line and the pressure equalizing line provided in the general PSA apparatus, and the on-off valve and the like provided in each of these lines (that is, the configuration having low relevance to the features of the present invention). ) Will be omitted, and the illustration will be omitted.

FIG. 1 is a schematic view showing an example of the configuration of the gas purification apparatus 10 according to the present embodiment. As shown in FIG. 1, the gas purification apparatus 10 includes a raw material gas supply source 1, a first PSA unit 2, a second PSA unit 3, a suction pump 4, a heat exchanger 5, a cooler 6, and a raw material line L1. A connection line L2, a first lead-out line L3, a second lead-out line L4, a heat recovery line L5, a regeneration line L6, and a recycled exhaust gas line L7 are provided.

In the gas purification apparatus 10 shown in FIG. 1, the raw material gas is supplied to the first PSA unit 2, and the gas containing propane and propene is supplied to the primary side of the second adsorption tower 3a described later. Further, in the gas purification apparatus 10, propene is already adsorbed on the second adsorbent 8b described later, and propene is derived from the primary side of the second adsorbent tower 3b described later.
Each component of the gas purification apparatus 10 will be described in detail below.

The first PSA unit 2 separates the component to be removed (carbon dioxide in this embodiment, hereinafter referred to as "carbon dioxide") from the raw material gas. The first PSA unit 2 has first adsorption towers 2a and 2b. In the first PSA unit 2, the number of the first adsorption towers 2a and 2b is not particularly limited as long as it is two or more.
The first adsorption towers 2a and 2b have a hollow cylindrical shape. The first adsorption towers 2a and 2b have the first adsorbents 7a and 7b inside. In this embodiment, the first adsorbents 7a and 7b are not particularly limited as long as they can adsorb carbon dioxide. Examples of the first adsorbents 7a and 7b include adsorbents containing molecular sieve coal, amine-supported alumina and the like. Examples of commercially available products of the first adsorbents 7a and 7b include molecular sieve activated carbon (MSC) "Granular Shirasagi 3K-M172" (pore diameter: 3 angstroms) manufactured by Osaka Gas Chemical Co., Ltd. However, the first adsorbents 7a and 7b are not limited to these examples.

The raw material line L1 is a line for supplying the raw material gas to the first PSA unit 2. In the raw material line L1, the end of the branched secondary side (downstream side) is connected to the primary side (upstream side) of the first adsorption towers 2a and 2b.
The connection line L2 is a first gas (propane (C ₃ H ₈ ) in this embodiment; hereinafter referred to as “propane”) and a second gas (propene (C ₃ H ₆ ) in this embodiment). This is a line for deriving a gas containing (hereinafter, referred to as “propene”) from the first PSA unit 2 to the second PSA unit 3. The connection line L2 connects the secondary side (downstream side) of the first PSA unit 2 and the primary side (upstream side) of the second suction towers 3a and 3b. Specifically, in the connection line L2, the branched first end is connected to each of the secondary sides of the first suction towers 2a and 2b, and the branched second end is the second suction tower 3a. , 3b are connected to each of the primary sides.

The second PSA unit 3 separates propane and propene. The second PSA unit 3 has a second suction tower 3a and a second suction tower 3b. In the present embodiment, the second PSA unit 3 has two second adsorption towers 3a and 3b, but in other embodiments, the number of the second adsorption towers is not particularly limited as long as it is two or more. ..
The second adsorption towers 3a and 3b have basically the same configuration and have a hollow cylindrical shape. The second adsorption towers 3a and 3b have the second adsorbents 8a and 8b inside. In this embodiment, the second adsorbents 8a and 8b are not particularly limited as long as they can adsorb propene. Examples of the second adsorbents 8a and 8b include adsorbents containing zeolite, silver ion-supported activated carbon, and the like. Examples of commercially available products of the second adsorbents 8a and 8b include zeolite "Zeolam A-4" (pore diameter: 4 angstroms) manufactured by Tosoh Corporation. However, the second adsorbents 8a and 8b are not limited to these examples.

The first out-licensing line L3 is a line through which propane derived from the secondary side of the second PSA unit 3 flows. In the first lead-out line L3, the branched first end is connected to each of the secondary sides of the second suction towers 3a and 3b, and the second end is connected to the reproduction line L6.
The second out-licensing line L4 is a line through which propene derived from the primary side of the second PSA unit 3 flows. In the second lead-out line L4, the branched first end is connected to each of the primary sides of the second adsorption towers 3a and 3b, and the second end is connected to the product gas tank (not shown). A suction pump 4 is provided on the second lead-out line L4. Propene is stored as product gas in the product gas tank (not shown).

The suction pump 4 is an example of a suction means for desorbing propene from the second adsorbents 8a and 8b in a state where propene is adsorbed on the second adsorbents 8a and 8b. As a result, a part of the propane separated by the second PSA unit 3 is not supplied as the regenerated gas of the second adsorbents 8a and 8b into the second adsorbents 3a and 3b, and the second adsorbent is used. The propene can be detached from 8a and 8b. A vacuum pump is preferable as the suction pump 4.

The heat recovery line L5 is a line through which propene led out from the second lead-out line L4 flows. The heat recovery line L5 branches from the second lead-out line L4 of the secondary side portion of the suction pump 4 and is connected to the secondary side of the second suction towers 3a and 3b. Specifically, in the heat recovery line L5, the first end is connected to the second lead-out line L4 of the secondary side portion of the suction pump 4, and the branched second end is the second suction tower 3a, It is connected to each of the secondary sides of 3b. The heat recovery line L5 is provided with a heat exchanger 5.

The heat exchanger 5 exchanges heat between the propene flowing through the heat recovery line L5 and the propane flowing through the first lead-out line L3. The heat exchanger 5 is provided at a position where the heat recovery line L5 and the first lead-out line L3 are close to each other across the heat recovery line L5 and the first lead-out line L3. As a result, heat can be exchanged between the propene flowing in the heat recovery line L5 and the propane flowing in the first lead-out line L3 while suppressing the loss of heat energy.

The regeneration line L6 is a line for supplying the regeneration gas for regenerating the first adsorbents 7a and 7b to the first adsorption towers 2a and 2b. However, in FIG. 1, for the sake of simplification, the connection between the reproduction line L6 and the first adsorption towers 2a and 2b is omitted.
In the reproduction line L6, the first end is connected to the second end of the first lead-out line L3, and the branched second end is connected to the secondary side of the first adsorption towers 2a and 2b, respectively. Be connected. As a result, propane can be supplied to the first adsorption towers 2a and 2b as a regenerating gas for regenerating the first adsorbents 7a and 7b. The reproduction line L6 is provided with a cooler 6.

The cooler 6 cools the propane supplied to the first adsorption towers 2a and 2b as the regenerated gas of the first adsorbents 7a and 7b. As a result, propane can be supplied to the first PSA unit 2 in a state where the temperature of propane is lowered.
The removal of carbon dioxide by the first adsorbents 7a and 7b is preferably performed at a temperature suitable for adsorbing carbon dioxide from the viewpoint of adsorption efficiency. Therefore, by providing the cooler 6, the temperature of the first adsorption towers 2a and 2b is less likely to drop excessively when the first adsorbents 7a and 7b are regenerated, and the first adsorption towers 2a and 2b are provided. It becomes easier to maintain a temperature suitable for removing carbon dioxide.
The recycled exhaust gas line L7 is a line for discharging the recycled exhaust gas from the first adsorption towers 2a and 2b. In the recycled exhaust gas line L7, the branched first end is connected to each of the primary sides of the first adsorption towers 2a and 2b.

Hereinafter, the PSA apparatus of the related technology will be described as a comparison target of the gas purification apparatus 10. FIG. 2 is a schematic view showing an example of the configuration of the gas purification device 100 according to the related technique of the gas purification device 10. As shown in FIG. 2, the gas purification device 100 has the same configuration as the gas purification device 10 except that the heat exchanger 5 and the heat recovery line L5 are not provided.

In the gas purification apparatus 100 shown in FIG. 2, the raw material gas is supplied to the first PSA unit 2, and the gas containing propane and propene is supplied to the primary side of the second adsorption tower 3a. Further, in the gas purification apparatus 100, propene is already adsorbed on the second adsorbent 8b, and propene is derived from the primary side of the second adsorbent tower 3b.

In this case, propene is adsorbed on the second adsorbent 8a, and propane is led out from the second adsorption tower 3a to the first lead-out line L3. When propene is adsorbed on the second adsorbent 8a, heat is generated due to the adsorption reaction. As a result, the temperature of the second adsorption tower 3a becomes high, and the temperature of the propane derived from the second adsorption tower 3a becomes high.

When the suction pump 4 desorbs the propene from the second adsorbent 8b, the propene is led out from the second suction tower 3b to the second lead-out line L4. When propene is desorbed from the second adsorbent 8b, cold heat is generated due to the desorption reaction. As a result, the temperature of the second adsorption tower 3b becomes low, and the temperature of the propene derived from the second adsorption tower 3b becomes low.

The adsorption reaction of propene by the second adsorbents 8a and 8b is preferably carried out at 50 to 250 ° C., more preferably 80 to 180 ° C., and 100 to 150 ° C. because the adsorption efficiency of propene is high. It is more preferable to carry out with. However, as described above for the gas purification apparatus 100, the temperature of the second adsorption tower 3b may decrease due to the generation of cold heat accompanying the desorption of propene. Therefore, when the proppen is adsorbed by the second adsorption tower 3b after the desorption of the propene by the second adsorption tower 3b, the temperature of the second adsorption tower 3b becomes lower than the temperature suitable for adsorbing the propen. There is. Therefore, in the gas purification apparatus 100, the adsorption efficiency of propene in the second adsorption tower may decrease.

On the other hand, since the gas purification device 10 includes the heat exchanger 5 and the heat recovery line L5, heat exchange can be performed between the propene in the heat recovery line L5 and the propane in the first lead-out line L3. can. In the gas purification apparatus 10 shown in FIG. 1, the temperature is relatively low because the propene in the heat recovery line L5 is desorbed from the second adsorbent 8b. Since the propane in the first lead-out line L3 is led out from the second adsorption tower 3a, the temperature is relatively high. Therefore, the propene in the heat recovery line L5 is heated by heat exchange with propane in the first lead-out line L3, and the temperature rises.

(Action effect)
In the gas purification apparatus 10, as shown in FIG. 1, after heat exchange is performed by the heat exchanger 5, the propene in the heat recovery line L5 can be introduced into the second adsorption tower 3b. Therefore, by heat exchange, the second adsorption tower 3b can be heated by the propene having a high temperature. As a result, it is not necessary to heat the second adsorption tower 3b from the outside, and it becomes easy to maintain the temperature of the second adsorption tower 3b at a temperature suitable for adsorption of propene.
Further, since it is possible to heat the inside of the second adsorption tower 3b by introducing the propene into the second adsorption tower 3b after heat exchange, the inside of the second adsorption tower 3b is uniformly added. It can be heated, and it becomes easy to effectively maintain the temperature of the second adsorbent. Therefore, according to the gas purification device 10, propene can be purified with high purity and high yield at a lower cost than the gas purification device 100.

Further, when the propene is adsorbed on the second adsorption tower 3b after the propene is desorbed on the second adsorption tower 3b, the temperature of the second adsorption tower 3b is close to the temperature suitable for adsorbing the propene. , The adsorption efficiency of propene is improved, and propene can be purified in high yield.

According to the gas purification apparatus 10, propane can be supplied to the first adsorption towers 2a and 2b as a regenerating gas for regenerating the first adsorbents 7a and 7b, so that propene stored as a product gas is first adsorbed. It is not necessary to use the agents 7a and 7b for regeneration. Therefore, the yield of propene, which is a product gas, is high, and propene can be purified with a higher yield.

Since the gas purification device 10 includes a heat recovery line L5 that branches from the second lead-out line L4 and is connected to the secondary side of the second adsorption towers 3a and 3b, the product gas is used via the heat exchanger 5. A certain propene can be circulated and used to maintain the temperature of the second adsorption towers 3a and 3b. As described above, since propene is used when heating the second adsorption towers 3a and 3b, the purity of propene as a product gas is unlikely to decrease, and propene can be purified with high purity.

Since the gas purification apparatus 10 includes the first PSA unit 2 and the second PSA unit 3, carbon dioxide is surely removed by the first PSA unit 2, and then propane and propene are removed by the second PSA unit 3. And can be separated. As a result, the purity of propene becomes high, and propene can be purified with high purity.
Since the gas purification device 10 includes the suction pump 4, the second adsorbents 8a and 8b do not supply a part of the propane separated by the second PSA unit 3 into the second adsorption towers 3a and 3b. The propene can be detached from. Therefore, propane is less likely to be mixed into propene, which is a product gas. As a result, the purity of propene becomes high, and propene can be purified with high purity.

Since the gas purification device 10 includes the cooler 6, the temperature of the first adsorption towers 2a and 2b is unlikely to drop excessively when the first adsorbents 7a and 7b are regenerated, and the first adsorption towers 2a and 2b are not easily lowered. Is easy to maintain at a temperature suitable for removing carbon dioxide. Therefore, the efficiency of removing carbon dioxide is improved, and the purity of propene, which is a product gas, is further increased.

In the present embodiment described above, the case where the propene adsorption reaction occurs with the second adsorbent 8a and the propene desorption reaction occurs with the second adsorbent 8b has been described as an example, but the second adsorption The same effect can be obtained even when the desorption reaction of propene occurs with the agent 8a and the adsorption reaction of propene occurs with the second adsorbent 8b.

Although the gas purification apparatus 10 according to the embodiment has been described above, this embodiment is presented as an example and is not intended to limit the scope of the invention. The gas purification apparatus 10 can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention.
For example, each of the connection line L2, the heat recovery line L5, and the regeneration line L6 may be provided with a tank for storing gas for the purpose of suppressing and stabilizing the fluctuation of the flow rate of the gas flowing through each line. good.

<Gas purification method>
Hereinafter, the gas purification method of the present embodiment using the gas purification apparatus 10 described above will be described. The gas purification method of this embodiment is a PSA type gas purification method. Therefore, in the following embodiments, the description of operations such as depressurization and pressure equalization performed by a general (that is, less relevant to the features of the present invention) PSA gas purification method will be omitted.

In the embodiment shown below, the raw material gas is supplied to the first PSA unit, and the first adsorbents 7a and 7b in the first adsorption towers 2a and 2b are adsorbed with a gas other than propane and propene, and the first Propane and propene are supplied from the adsorption towers 2a and 2b to the second adsorption tower 3b, and the propene is adsorbed on the second adsorbent 8b, which will be described as an example.
That is, in the following embodiment, carbon dioxide is adsorbed on the first adsorbents 7a and 7b in the first adsorbent towers 2a and 2b, and is adsorbed on the second adsorbent 8b in the second adsorbent tower 3b. The explanation of the gas purification method is started from the state where the propene is adsorbed.

Hereinafter, the gas purification method of the present embodiment will be described with reference to FIG. In FIG. 1, the direction of the arrow means the direction in which the gas is flowing.

In the gas purification method of the present embodiment, the raw material gas is supplied to the first PSA unit 2, and gases other than propane and propene are adsorbed on the first adsorbents 7a and 7b in the first adsorption towers 2a and 2b. .. As a result, carbon dioxide is removed from the raw material gas.
Next, a gas containing propane and propene is led out from the first PSA unit 2 to the second PSA unit 3, and propane and propene are supplied to the second adsorption tower 3a. Then, propene is adsorbed on the second adsorbent 8a. As a result, propane is led out from the second adsorption tower 3a to the first lead-out line L3, and the propane and propene are separated.

In this embodiment, propene is desorbed from the second adsorbent 8b. Then, a part of the propene desorbed from the second adsorbent 8b is introduced into the heat recovery line L5, and the rest of the propene desorbed from the second adsorbent 8b is recovered as a product gas from the second derivation line L4. do. When a part of the propene desorbed from the second adsorbent 8b is introduced into the heat recovery line L5, it is passed through the second lead-out line L4. Further, when a part of the propene is introduced into the heat recovery line L5, an on-off valve may be provided in the heat recovery line L5 to open / close the on-off valve, and a pump may be provided in the heat recovery line L5. Propene may be sucked with a pump.

Flow rate _{V L5} of propene introduced into heat recovery line L5, compared flow rate of 100 vol% of propene desorbed from the second adsorbent 8b, preferably 5 to 50 vol%, more preferably 5 to 25% by volume, 5 to 10% by volume is more preferable. When _VL5 is equal to or higher than the lower limit, the yield of propene, which is a product gas, is further increased. When _VL5 is not more than the above upper limit value, propene can be purified as a product gas at a lower cost.

In the present embodiment, the propene flowing through the heat recovery line L5 is heated by the heat exchanger 5. Heating in the heat exchanger 5 is performed, for example, as follows.
In this embodiment, propane is led out from the second adsorption tower 3a to the first lead-out line L3. When propene is adsorbed on the second adsorbent 8a, heat is generated due to the adsorption reaction. Therefore, the propane derived from the second adsorption tower 3a to the first extraction line L3 has a relatively high temperature.
On the other hand, in the second adsorption tower 3b, propene is desorbed from the second adsorbent 8b, and cold heat is generated by the desorption reaction. Therefore, the propene led out from the second adsorption tower 3b to the second lead-out line L4 has a relatively low temperature, and the heat recovery line L5 on the primary side (upstream side of the flow of propene) of the heat exchanger 5 Propene flowing through is also relatively cold.
As described above, in the heat exchanger 5, the relatively low temperature propene in the heat recovery line L5 is heated by the relatively high temperature propane in the first lead-out line L3.

Next, in the present embodiment, the propene heated by the heat exchanger 5 is introduced from the heat recovery line L5 into the second adsorption tower 3b. By introducing the propene heated in this way into the second adsorption tower 3b, the second adsorption tower 3b can be heated.

In the present embodiment, the propane separated by the second PSA unit 3 may be introduced from the first lead-out line L3 to the regeneration line L6. As a result, propane can be used as the regenerated gas of the first adsorbents 7a and 7b in the first adsorbent towers 2a and 2b, and propene, which is a product gas, is used as the regenerated gas of the first adsorbents 7a and 7b. No need. When propane is used with the regenerated gas of the first adsorbents 7a and 7b, the propane may be cooled by the cooler 6. This makes it easier to maintain the first adsorption towers 2a and 2b at a temperature suitable for removing carbon dioxide.

(Action effect)
In the gas purification method of the present embodiment described above, since the gas purification apparatus 10 is used, the heat of propane led out from the second adsorption tower 3a to the first lead-out line L3 is used to heat the propene in the heat recovery line. It can be used for heating the second adsorption tower 3b. Therefore, it is not necessary to heat the second adsorption tower 3b from the outside, and propene can be purified at a lower cost as compared with the case where the gas purification apparatus 100 is used.

According to the gas purification method of the present embodiment, the heating of the second adsorption tower 3b makes it easier to maintain the temperature of the second adsorption tower 3b at a temperature suitable for the adsorption of propene, so that the adsorption efficiency of propene is improved. It improves and can purify propene in high yield.
Further, in the present embodiment, carbon dioxide is adsorbed on the first adsorbents 7a and 7b, carbon dioxide is surely removed by the first PSA unit 2, and then propene is desorbed from the second adsorbent. The purity of propene becomes high, and propene can be manufactured with high purity.

In the present embodiment described above, the case where propene is adsorbed on the second adsorbent 8a and the propene is desorbed from the second adsorbent 8b has been described as an example, but the propene is adsorbed on the second adsorbent 8a. The same effect can be obtained even when the propene is desorbed from the second adsorbent 8a and the propene is adsorbed on the second adsorbent 8b in this state.

In the present embodiment described above, the heat of propane led out to the first lead-out line L3 is used to heat the propene in the heat recovery line, and the second adsorption tower is heated by heat exchange. As a feature, the second adsorption towers 3a and 3b may be heated from the outside as long as the effects of the present invention are not impaired. When heating from the outside, heating with steam or the like may be performed.

<Example>
Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to the following description.

(Abbreviation)
_VL4 : Flow rate of product gas (propene) in the second PSA unit 3 [Nm ³ / h].
P _L3: second adsorption tower 3a, the pressure during adsorption of propene in 3b [kPaG].
P _L4: second adsorption tower 3a, desorption at a pressure of propene in 3b [kPaA].
_VL5 : Ratio [%] of the flow rate of propene introduced into the heat recovery line L5 to 100% by volume of the flow rate of propene desorbed from the second adsorbent.
C ₁ : Concentration of propene in the product gas [volume%].
C ₂ : Concentration of impurities in the product gas [volume%].

(Example 1)
In Example 1, the raw material gas was purified by the PSA method using the gas purification apparatus 10, and propene was recovered as a product gas. The raw material gas used in Example 1 contained 50% by volume of propane, 25% by volume of propene, and 25% by volume of carbon dioxide.
In Example 1, first, the raw material gas was supplied to the first PSA unit 2 to remove carbon dioxide. In the first PSA unit 2, molecular sieve activated carbon (MSC) "Granular Shirasagi 3K-M172" (pore diameter: 3 angstroms) manufactured by Osaka Gas Chemical Co., Ltd. was used as the first adsorbent. Next, propane and propene were supplied to the second PSA unit 3, and the propane and propene were separated by the PSA method. In the second PSA unit 3, a zeolite "Zeolam A-4" (pore diameter: 4 angstroms) manufactured by Tosoh Corporation was used as the second adsorbent. The switching time between adsorption and desorption of the second adsorption tower in the second PSA unit 3 was 90 seconds, and propene was recovered as a product gas from the second lead-out line L4 under the conditions shown in Table 1. In Example 1, the second adsorption towers 3a and 3b were heated by steam so that the second adsorption towers 3a and 3b could be easily maintained at a set temperature T suitable for adsorption of propene.

(Comparative Example 1)
In Comparative Example 1, propene was recovered as a product gas under the conditions shown in Table 1 in the same manner as in Example 1 except that the gas purification apparatus 100 was used. In Comparative Example 1, the second adsorption towers 3a and 3b were heated by steam.

(Measurement of temperature of the second adsorption tower)
In Example 1 and Comparative Example 1, the temperature at which propene was adsorbed by the second adsorption towers 3a and 3b was measured, respectively. As a result, in Example 1, the temperatures of the second adsorption towers 3a and 3b fluctuated within a range of ± 10 ° C. from the set temperature T. On the other hand, in Comparative Example 1, the temperatures of the second adsorption towers 3a and 3b were 20 to 30 ° C. lower than the set temperature T. From this result, it was shown that according to the gas purification apparatus 10, the second adsorption towers 3a and 3b can be effectively heated by using a part of the propene in the heat recovery line L5. Then, in Example 1, it was shown that the temperature of the second adsorption towers 3a and 3b can be easily maintained at a temperature suitable for adsorption of propene.
Further, in Example 1, C ₁ was 44% by volume and C ₂ was 56% by volume. On the other hand, in Comparative Example 1, C ₁ was 34% by volume and C ₂ was 66% by volume.
From the above, it was found that according to Example 1, the product gas can be purified with high purity and high yield at a lower cost than in Comparative Example 1.

The gas purification apparatus and gas purification method of the present invention can be industrially used as a technique for recovering a high concentration of hydrocarbon gas at a high recovery rate from, for example, a mixture containing an organic substance containing a plurality of hydrocarbons and an inorganic substance. ..

1 ... Source of raw material gas, 2 ... 1st PSA unit, 2a, 2b ... 1st adsorption tower, 3 ... 2nd PSA unit, 3a, 3b ... 2nd adsorption tower, 4 ... Pump, 5 ... Heat exchanger, 6 ... cooler, 7a, 7b ... first adsorbent, 8a, 8b ... second adsorbent, 10,100 ... gas purification device, L1 ... raw material line, L2 ... connection line, L3 ... th 1 lead-out line, L4 ... second lead-out line, L5 ... heat recovery line, L6 ... regeneration line, L7 ... recycled exhaust gas line

Claims (4)

The first gas and; second gas and; removal target component and; from a feed gas containing, a gas purifying device for purifying the product gas at a pressure swing adsorption method,
The component to be removed is a gas other than the first gas and the second gas.
Two or more first adsorption towers having a first adsorbent that adsorbs the component to be removed, and
Two or more second adsorption towers having a second adsorbent that adsorbs the second gas, and
A connection line that connects the secondary side of the first adsorption tower and the primary side of the second adsorption tower and allows the first gas and the second gas to flow.
A first lead-out line connected to the secondary side of each of the second adsorption towers and through which the first gas flows,
A second lead-out line connected to the primary side of each of the second adsorption towers and through which the second gas flows,
A suction means provided in the second lead-out line to desorb the second gas from the second adsorbent,
A heat recovery line that branches off from the second lead-out line and is connected to the secondary side of each of the second adsorption towers.
A heat exchanger that exchanges heat between the second gas flowing through the heat recovery line and the first gas flowing through the first lead-out line.
A gas purification device. It is further provided with a regeneration line which is connected to the secondary side of the first adsorption tower and through which a regeneration gas for regenerating the first adsorbent flows, and the regeneration line and the first lead-out line are connected. The gas purification apparatus according to claim 1. A pressure fluctuation adsorption type gas purification method using the gas purification apparatus according to claim 1 or 2.
The component to be removed is adsorbed on the first adsorbent, the first gas and the second gas are supplied from the first adsorption tower to the second adsorption tower b, and the second adsorption After adsorbing the second gas on the second adsorbent b contained in the column b,
The second gas is desorbed from the second adsorbent b,
The second gas is introduced into the heat recovery line via the second lead-out line.
The second gas flowing through the heat recovery line is heated by the heat exchanger,
A gas purification method in which the second gas is introduced from the heat recovery line into the second adsorption tower b. When the second gas is heated by the heat exchanger, the first gas and the second gas are supplied to the second adsorption tower a different from the second adsorption tower b, and the second gas is supplied. The second gas is adsorbed on the second adsorbent a contained in the adsorption tower a, and the second gas is adsorbed.
The gas purification method according to claim 3, wherein the first gas is led out from the second adsorption tower a to the first lead-out line.

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