JP4313882B2 - Method for removing organic impurities in methanol decomposition gas by closed TSA method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a methanol decomposition gas generated when carbon monoxide is generated in a methanol decomposition process. A closed TSA method is used to remove organic impurities such as dimethyl ether, methyl formate, and unreacted methanol contained in the methanol decomposition gas. It is related with the removal method.
[0002]
[Prior art]
Conventionally, it is known that carbon monoxide and hydrogen are obtained by a methanol decomposition process. The methanol decomposition process is a process in which methanol is decomposed to generate carbon monoxide and hydrogen. Carbon monoxide and hydrogen mixed in the methanol decomposition gas are further separated by CO-PSA or a cryogenic separator, Product gas.
[0003]
However, in this decomposition process, in addition to carbon monoxide and hydrogen, reaction by-products such as dimethyl ether and methyl formate are generated and remain in the methanol decomposition gas, and unreacted methanol also remains. For this reason, in order to separate the methanol cracked gas into products such as carbon monoxide and hydrogen, it is necessary to remove these organic impurities from the methanol cracked gas before separation with CO-PSA or the like. . As a method for removing organic impurities from the methanol decomposition gas, a method using methanol absorption and activated carbon adsorption is known. By passing the methanol decomposition gas through a methanol absorption tower or an activated carbon adsorption tower, the organic impurities are substantially eliminated. A purified gas not contained can be obtained. However, since the adsorbent used in the adsorption tower has a limited adsorption capacity, after adsorbing to some extent, the adsorbent must be desorbed by heating the adsorbent or the like to regenerate the adsorbent. A TSA method (thermal swing method) has been conventionally known as a method for performing such an adsorbent regeneration step simultaneously with a purified gas production step. In the TSA method, two adsorption towers are used, and one adsorption tower is used for the purification gas production process, and at the same time, the other adsorption tower is used for the regeneration process by heat desorption of the adsorbent. By alternately and repeatedly carrying out the adsorption tower, the production of purified gas can be carried out without interruption, and the production efficiency is high.
[0004]
In the TSA method, as a method of regenerating the adsorbent in the adsorption tower, the organic gas from the outside of the TSA process apparatus is further purified with CO-PSA to produce a product gas by refining the product gas. A method is known in which offgas containing impurities is heated as a medium, introduced into an adsorption tower, organic impurities are desorbed to regenerate the adsorbent, and then the adsorption tower is cooled.
[0005]
[Problems to be solved by the invention]
However, when nitrogen gas is used as the medium to be regenerated, there is a problem that it is expensive to purchase nitrogen gas or to construct facilities for introducing and discharging nitrogen gas into the TSA process system. Further, when off-gas is used, there is a problem that it is expensive to construct a facility for introducing off-gas into the TSA process system.
[0006]
Further, nitrogen gas and off-gas contain no or almost no organic impurities. For this reason, the adsorbent in the adsorption tower adsorbs CO gas instead of low-concentration organic impurities, and the concentration of CO gas in the resulting purified gas decreases, so that CO-PSA, a cryogenic separator, etc. There is a problem that it does not work well, it becomes difficult to continue the operation, and the production of high purity CO gas may be adversely affected.
[0007]
Accordingly, an object of the present invention is to use a methanol decomposition gas in the system without using a gas introduced from outside the TSA process apparatus system as a regeneration medium of the adsorption tower in the method for removing organic impurities in the methanol decomposition gas by the TSA method. Thus, there is provided a method for removing organic impurities that can obtain a high-purity purified gas without lowering the CO gas concentration in the purified gas without the need for the medium cost and the introduction / discharge processing facility. There is.
[0008]
[Means for Solving the Problems]
In this situation, the present inventor has conducted extensive studies, and as a result, two absorption towers that alternately perform adsorption and desorption, a methanol absorption tower that absorbs and removes organic impurities in methanol decomposition gas by methanol absorption, and methanol decomposition A device equipped with a heating means for heating a gas and a pre-adsorption tower provided as necessary, using a methanol decomposition gas in the TSA process apparatus system as a regeneration medium of the adsorption tower, and using this gas as two adsorption towers, The inventors have found that the above object can be achieved by circulating the methanol absorption tower, heating means, and, if necessary, the preliminary adsorption tower in a predetermined procedure, and have completed the present invention.
[0009]
That is, the invention described in claim 1 uses two adsorption towers that alternately perform the adsorption process and the heat desorption process, one of the adsorption towers is in the adsorption process, and the methanol decomposition gas containing organic impurities is allowed to pass through for adsorption. the organic impurity is adsorbed with the production of refining has been methanolysis gas agent, the other adsorption tower is in the thermal desorption process, organic adsorbed to the adsorbent by introducing the methanolysis gas heated in the adsorption tower In the method for removing organic impurities in the methanol decomposition gas by the TSA method for desorbing impurities, the methanol decomposition gas containing organic impurities discharged from the adsorption tower in the heat desorption step is introduced into the methanol absorption tower, While absorbing a part of the organic impurities, the methanol decomposition gas containing the remaining organic impurities discharged from the methanol absorption tower is absorbed. A first step of returning to the adsorption tower in the process, a second step of precooling the other adsorption tower by introducing an unheated methanol decomposition gas instead of the heated methanol decomposition gas into the other adsorption tower. The present invention provides a method for removing organic impurities in methanol decomposition gas by a closed TSA method characterized by sequentially performing the steps. Therefore, the methanol decomposition gas in the system can be used as the regeneration medium of the adsorption tower without using the gas introduced from outside the TSA process apparatus system, the medium cost and the cost of the introduction / discharge treatment equipment are unnecessary, and A relatively high-purity purified gas having an organic impurity concentration of about several tens of ppm can be obtained without reducing the CO gas concentration in the purified gas.
[0010]
Further, in the invention described in claim 2, following the second step, the raw material methanol decomposition gas is directly introduced into the other adsorption tower in the direction opposite to the gas flow of the second step to cool the adsorption tower. A method for removing organic impurities in the methanol decomposition gas by the closed TSA method according to claim 1, further comprising a third step of introducing the methanol decomposition gas discharged from the adsorption tower into the methanol absorption tower. It is to provide. Therefore, in addition to the same effects as the invention of the first aspect, it is possible to cool the bottom of the adsorbent layer, which is insufficiently cooled by the preliminary cooling, and to stabilize the adsorption performance of the adsorption tower. .
[0011]
The invention according to claim 3 is that the heated methanol decomposing gas used in the heat desorption step is one in which at least a part of organic impurities has been removed by passing through a preliminary adsorption tower in advance. Subsequent to the second step, the methanol decomposition gas as a raw material is directly introduced into the other adsorption tower in the direction opposite to the gas flow in the second step to cool the adsorption tower, and the methanol decomposed from the adsorption tower is decomposed. Providing a third step of heating the gas and introducing it into the pre-adsorption tower to thermally desorb organic impurities from the pre-adsorption tower and introducing the methanol decomposition gas discharged from the pre-absorption tower into the methanol absorption tower; A method for removing organic impurities in methanol decomposition gas by the closed TSA method according to claim 1 is provided. Therefore, in addition to the effects similar to those of the invention described in claims 1 and 2, since the methanol decomposing gas containing no organic impurities is used in the heat desorption process and the preliminary cooling process, the organic impurities are used in the adsorption process in the subsequent process. Can be removed sufficiently and stably. For this reason, an extremely high purity purified gas having an impurity concentration of 1 ppm or less can be obtained.
[0012]
In the invention according to claim 4, the method for regenerating methanol that has absorbed the organic impurities in the methanol decomposition gas in the methanol absorption tower is obtained by further purifying the purified methanol decomposition gas by a CO-PSA method. The method for removing organic impurities in the methanol decomposition gas by the closed TSA method according to any one of claims 1 to 3, which is a gas stripping method or distillation method using off-gas. Therefore, when off-gas refined by the CO-PSA method in the subsequent step can be used, off-gas is used, and in an environment where heat sources are abundant, the heat source can be used effectively, and the scope for selecting a regeneration method is widened.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a process flow sheet showing a method for removing organic impurities in methanol decomposition gas by the closed TSA method according to the first embodiment of the present invention. In FIG. 1, 4 is a preliminary adsorption tower filled with an adsorbent, 5 is a heating means, 6 and 7 are adsorption towers filled with an adsorbent, 10 is a methanol absorption tower, and 11 is a methanol regeneration tower. The methanol decomposition gas generated by the methanol decomposition process as a raw material is supplied into the system of the methanol decomposition gas removal apparatus of the present invention through the raw material main pipe 101 and the branch pipe 102. In the figure, solid arrows indicate the flow direction of the methanol decomposition gas in the first and second steps, and broken line arrows indicate the flow direction of the methanol decomposition gas in the third step (hereinafter the same applies to FIGS. 2 and 3). is there.). Methanol decomposition gas contains organic by-products such as unreacted methanol, dimethyl ether and methyl formate as well as carbon monoxide and hydrogen, which are the target products obtained by decomposing methanol. The content of impurities is usually 0.3 to 0.6% by volume.
[0014]
(First step)
In FIG. 1, the first step is that the valves 1, 73, 64, 71 and 62 are open, the valves 74, 64, 72 and 61 are closed, the three-way valve 2a is in communication with the pipes 101 and 103, and the three-way valve. In 2b, the pipes 104 and 105 are in communication. The adsorption tower 7 is in the adsorption process, and the adsorption tower 6 is in the heat desorption process. As the adsorbent filled in the adsorption towers 6 and 7, activated carbon is used.
[0015]
A part of the raw material methanol decomposition gas is introduced into the preliminary adsorption tower 4 through the pipes 101 and 103, and a part of the organic impurities in the methanol decomposition gas is adsorbed and removed. The pre-adsorption tower 4 is filled with an adsorbent such as activated carbon, and the amount of the activated carbon may be obtained by removing a part of the organic impurities in the methanol decomposition gas. As the parts by weight, usually 12 to 40 parts by weight, preferably about 30 to 40 parts by weight is sufficient. The clean gas from which the organic impurities have been removed in the preliminary adsorption tower 4 passes through the pipe 110 and is heated to usually 150 to 250 ° C., preferably 170 to 220 ° C. by the heating means 5. It is introduced in a downward flow to desorb organic impurities and regenerate the adsorbent. The methanol decomposition gas discharged from the adsorption tower 6 passes through the pipes 109, 104 and 105, is sequentially cooled by the absorption tower cooler 8 and the absorption tower heat exchanger 9, and is introduced into the methanol absorption tower 10. Unreacted methanol and organic impurities in the methanol decomposition gas discharged from the adsorption tower 6 are usually 0.3 to 1.2% by volume. In the methanol absorption tower 10, a part of the organic impurities in the methanol decomposition gas is absorbed and removed by the methanol solution.
[0016]
The methanol solution of the absorbent is circulated through the cooler 18, the methanol absorption tower 10, and the methanol regeneration tower 11 in this order by the operation of the pump 12, and is countercurrently contacted with the methanol decomposition gas introduced into the methanol absorption tower 10. Absorbs and removes organic impurities. The temperature of the methanol solution supplied to the absorption tower 10 is usually −5 to −15 ° C. The methanol solution that has absorbed impurities in the methanol decomposition gas is stripped by introduction of the off gas 16 in the regeneration tower 11, and the gas containing organic impurities is released to the atmosphere as an off gas from a discharge pipe 17 provided at the top of the tower. As the off gas, an off gas after further purifying the methanol decomposition gas by the CO-PSA method can be used.
[0017]
On the other hand, the methanol decomposition gas containing residual organic impurities discharged from the top of the methanol absorption tower 10 is heat-exchanged with the gas introduced into the methanol absorption tower 10 in the adsorption tower heat exchanger 9 and passes through the pipe 107. It is introduced into the adsorption tower 7 together with a part of the raw material methanol decomposition gas supplied from the pipe 102. In the adsorption tower 7, purified methanol decomposition gas substantially free of organic impurities is produced, and this purified gas is sent to a CO-PSA or a cryogenic separation device (not shown) in the next step through a pipe 106. . The amount of organic impurities in the purified methanol decomposition gas is 1 ppm or less.
[0018]
The first step proceeds to the next second step when the inside of the adsorption tower 6 is sufficiently heated and organic impurities are desorbed from the adsorbent. The determination method of the transition is performed by temperature or time. For example, a method may be set in advance such that the temperature in the tower at the center or bottom of the adsorption tower 6 rises to 100 ° C. or shifts when a predetermined time elapses. The time required for the first step is not particularly limited because it varies depending on the apparatus specifications, but is, for example, 2 to 3 hours.
[0019]
(Second step)
The second step is the same as the first step except that the adsorption column 6 is preliminarily cooled by introducing an unheated methanol decomposition gas instead of the heated methanol decomposition gas of the first step. Similarly, the adsorption tower 7 is an adsorption process, and the adsorption tower 6 is a preliminary cooling process. That is, the clean gas discharged from the preliminary adsorption tower 4 bypasses the heating means 5 (or the heating means 5 is turned off) and is introduced into the adsorption tower 6 through the pipe 108. Thereby, the temperature of the methanol decomposition gas introduced into the adsorption tower 6 gradually decreases, and the adsorbent in the adsorption tower 6 is gradually cooled. The adsorption tower 6 is usually cooled to 50 to 100 ° C., preferably 70 to 90 ° C., by this preliminary cooling. By providing the second step and the third step described later, the precooled adsorbent can be smoothly transferred to the adsorption step.
[0020]
The second step proceeds to the next third step when the inside of the adsorption tower 6, in particular, the upper part and the central part are sufficiently cooled. The determination method of the transition is performed by temperature or time. For example, there is a method of setting in advance so that the temperature in the tower at the center of the adsorption tower 6 is lowered to 50 ° C. or when a predetermined time has passed. The time required for the second step is not particularly limited because it varies depending on the apparatus specifications, but is, for example, 10 minutes to 1 hour.
[0021]
(Third step)
In FIG. 1, the state of the valve in the third step is the same as that in the first step, except that the three-way valve 2a is in communication with the pipes 101 and 104 and the three-way valve 2b is in communication with the pipes 103 and 105. 7 is in the adsorption step, and the adsorption tower 6 is in the heat desorption step. That is, the methanol decomposition gas of the raw material at room temperature is directly introduced into the adsorption tower 6 through the pipes 101, 104 and 109 in the upward flow in the figure, and the adsorbent in the adsorption tower 6 is further cooled. The methanol decomposition gas discharged from the adsorption tower 6 passes through the pipe 108 and is heated to 150 to 250 ° C., preferably 170 to 220 ° C. by the heating means 5, and then introduced into the preliminary adsorption tower 4 through the pipe 110. The organic impurities are heated and desorbed to regenerate the adsorbent. The concentration of organic impurities in the methanol decomposition gas discharged from the adsorption tower 6 is usually 1 ppm or less. Moreover, the organic impurity in the methanol decomposition gas discharged | emitted from the preliminary adsorption tower 4 is 0.3 to 1.6 volume% normally. The methanol decomposition gas discharged from the preliminary adsorption tower 4 passes through the pipes 103 and 105, is sequentially cooled by the absorption tower cooler 8 and the absorption tower heat exchanger 9, and is introduced into the methanol absorption tower 10. The flow of the methanol decomposition gas that has absorbed the organic impurities discharged from the methanol absorption tower 10 and the remaining organic impurities is the same as in the first step. In the third step, the adsorbent on the bottom side, which has become insufficiently cooled by the preliminary cooling in the second step, is sufficiently cooled, so that an adsorption tower with further stable adsorption performance can be obtained. Further, the adsorbent of the preliminary adsorption tower 4 is regenerated, and the organic impurities adsorbed by the preliminary adsorption tower 4 are released out of the system.
[0022]
The third step proceeds to the next fourth step when the inside of the adsorption tower 6 is sufficiently cooled. The determination method of the transition is performed by temperature or time. For example, a method may be set in advance such that the temperature inside the tower at the top of the adsorption tower 6 drops to 50 ° C. or shifts when a predetermined time elapses. The time required for the third step is not particularly limited because it varies depending on the apparatus specifications, but is, for example, 1 to 2 hours.
[0023]
(4th to 6th steps)
The fourth step is the same step as the first step, the fifth step is the second step, the sixth step is the third step, and the one adsorption tower 7 and the other adsorption tower 6 are replaced. That is, in FIG. 1, in the fourth step, the valves 1, 74, 63, 72 and 61 are open, the valves 73, 63, 71 and 62 are closed, the three-way valve 2a is in a state where the pipes 101 and 103 are in communication, In the three-way valve 2b, the pipes 104 and 105 are in communication, the adsorption tower 6 and the preliminary adsorption tower 4 are in the adsorption process, the adsorption tower 7 is in the heat desorption process, and the heating means 5 is in the ON state. In the fifth step, the adsorption tower 6 and the preliminary adsorption tower 4 are in the adsorption process, the adsorption tower 7 is in the preliminary cooling process, and the heating means 5 is in the OFF state. In the sixth step, the adsorption tower 6 is an adsorption process, the adsorption tower 7 is a cooling process, the preliminary adsorption tower 4 is a heat desorption process, and the heating means 5 is in an ON state.
[0024]
According to the method of the first embodiment of the present invention, the regeneration medium from which the organic impurities in the methanol decomposition gas have been removed in advance is introduced into the heat desorption process of the adsorption tower. Is removed sufficiently and stably. In addition, since the concentration of organic impurities in the resulting purified gas is low and stable, there is little variation in the composition of the purified gas supplied to the CO-PSA that further purifies the purified gas or the cryogenic separation device, and the normal operation of these devices. Does not interfere with driving.
[0025]
Next, a method for removing organic impurities in the methanol decomposition gas by the closed TSA method in the second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a process flow sheet showing the second embodiment. In FIG. 2, the same components as those in FIG. 1 are denoted by the same reference numerals, description thereof will be omitted, and different points will be described. In other words, the second embodiment differs from the first embodiment in that the preliminary adsorption tower 4 is eliminated and the preliminary adsorption tower 4 is passed through the pipe 103 in the first embodiment. That is, the removal of the organic impurities in the methanol decomposition gas to be introduced is omitted and the regeneration of the preliminary adsorption tower 4 is omitted. Therefore, the heated or non-heated methanol decomposition gas supplied through the pipe 108 to the heat desorption process and the precooling process of the adsorption tower 6 in the first process and the second process contains organic impurities in the raw material composition. It is. The methanol decomposition gas that has finished cooling the adsorption tower 6 in the third step passes through the pipe 108, bypasses the heating means 5 (heating means OFF state), and passes through the pipes 110, 103, 105 to absorb the absorption tower cooler. 8 and absorption tower heat exchanger 9 are sequentially cooled and introduced into methanol absorption tower 10. According to the method in the second embodiment, the removal device that performs this method can be simplified. Further, the concentration of organic impurities in the purified gas obtained from the pipe 106 is, for example, about several tens of ppm, which is higher than that in the first embodiment, but other than that, it is the same as that in the first embodiment. Has the effect of.
[0026]
Next, a method for removing organic impurities in the methanol decomposition gas by the closed TSA method in the third embodiment of the present invention will be described with reference to FIG. FIG. 3 is a process flow sheet showing the third embodiment. In FIG. 3, the same components as those in FIG. 2 are denoted by the same reference numerals, and the description thereof will be omitted and different points will be described. That is, the third embodiment differs from the second embodiment in that the three-way valve 2a, the three-way valve 2b, and unnecessary piping related thereto are omitted in the second embodiment. In the first and second embodiments, the cooling step of the adsorption tower by the raw material methanol decomposition gas in the third step is omitted. According to the method in the third embodiment, the removal apparatus that performs this method can be simplified. In addition, the concentration of organic impurities in the purified gas obtained from the pipe 106 is higher than that in the first and second embodiments, but the other operations are the same as those in the first and second embodiments. Play.
[0027]
The method for removing organic impurities by the closed TSA method of the present invention is not limited to the above embodiment, and various modifications or additions are possible without departing from the gist of the present invention. For example, as a method for regenerating methanol in the regeneration tower 11, organic impurities in the methanol solution may be removed by distillation using the regeneration tower 11 as a distillation tower in addition to the stripping method. FIG. 4 is a process flow sheet when the regeneration tower 11 is a distillation tower in FIG. That is, in FIG. 4, a part of the methanol solution regenerated by the regeneration tower 11 and extracted from the bottom is heated by the reboiler 19 and returned to the regeneration tower 11 to maintain the temperature at the bottom of the regeneration tower. On the other hand, the remaining methanol solution extracted from the bottom is heat-exchanged by the heat exchanger 20 with the methanol solution put in the regeneration tower 11, cooled by the cooler 18, and fed to the methanol absorption tower 10. Examples of the heat source 14 of the reboiler 19 include heat transfer oil and steam. The off-gas released from the pipe 17 can be used as fuel for the heater for the heat medium.
[0028]
The method for removing organic impurities by the closed TSA method of the present invention can be used for removing organic impurities in the methanol decomposition gas produced by the methanol decomposition process. In addition, the purified gas produced by the removal method of the present invention is supplied to a CO-PSA apparatus or a cryogenic separation apparatus to be further purified and separated, and the further purified and separated gas is used as a high-purity gas for various organic chemistry. Used as raw material or reducing gas.
[0029]
【Example】
Next, the present invention will be described more specifically with reference to examples.
Example 1
Removal of organic impurities in methanol decomposition gas (hereinafter also referred to as “source gas”) is performed by a method according to the first embodiment described above using an apparatus having the following specifications represented by the process flow sheet of FIG. went. As a result of analysis, the purified gas composition produced after one cycle of the first to sixth steps contains 66.6% hydrogen, 32.9% carbon monoxide, and carbon dioxide and methane as other residual gases. The concentration of organic impurities such as dimethyl ether, methyl formate and unreacted methanol was 1 ppm or less. From this result, it can be seen that the produced purified gas has a reduced carbon monoxide concentration and has only impurities removed as compared with the composition of the raw material methanol decomposition gas.
[0030]
(Organic impurity removal equipment by closed TSA method)
Source gas composition: Hydrogen 66.1%, carbon monoxide 32.7%, other residual gases include carbon dioxide 0.3%, methane 0.2%, dimethyl ether 870 ppm, methyl formate 20 ppm, unreacted methanol 0.5%
・ Raw gas supply amount: 42 m ³ / min ・ Adsorption tower: Activated carbon; Shirakaba pellets (manufactured by Takeda Pharmaceutical Co., Ltd.), activated carbon amount per unit is 3,700 kg
・ Preliminary adsorption tower: Activated carbon; Shirakaba pellets (manufactured by Takeda Pharmaceutical Company Limited), the amount of activated carbon per unit is 2,000 kg
・ Temperature of heated methanol decomposition gas: 190 ℃
First step: The required time is 2.3 hours, and the temperature is switched to the second step at a temperature of 100 ° C. at the bottom of the adsorption tower. The ratio of the raw material gas supplied to the pipe 101 side in the raw material gas is 80%.
・ Second step: Switched to the third step at a temperature of 50 ° C. at the bottom of the adsorption tower for a required time of 0.5 hours. [0031]
【The invention's effect】
According to the method for removing organic impurities by the closed TSA method of the present invention, by using the methanol decomposition gas in the system without using the gas introduced from outside the TSA process apparatus system as the regeneration medium of the adsorption tower, the medium cost and introduction -Expenses such as exhaust treatment facilities are unnecessary, and high-purity CO gas can be stably produced without reducing the CO gas concentration in the refined gas.
[Brief description of the drawings]
FIG. 1 is a flow sheet showing a method for removing organic impurities in methanol decomposition gas by a closed TSA method according to a first embodiment of the present invention.
FIG. 2 is a flow sheet showing a method for removing organic impurities in methanol decomposition gas by a closed TSA method according to a second embodiment of the present invention.
FIG. 3 is a flow sheet showing a method for removing organic impurities in methanol decomposition gas by a closed TSA method in a third embodiment of the present invention.
FIG. 4 is a process flow sheet showing a case where the regeneration tower is a distillation tower in FIG.
[Explanation of symbols]
1, 61-64, 71-74 Valve 2a, 2b Three-way valve 4 Preliminary adsorption tower 5 Heating means 6, 7 Adsorption tower 8 Absorption tower cooler 9 Absorption tower heat exchanger 10 Methanol absorption tower 11 Regeneration tower 12 Absorption tower circulation pump 14 Heat transfer oil 15 Cooling water 16 Off-gas from CO-PSA 17 Off-gas from regeneration tower 18 Methanol cooler 19 Reboiler 20 Heat exchangers 101 to 110 Piping

Claims (4)

Using an adsorption tower 2 groups alternately perform the adsorption step and the thermal desorption process, is in the adsorption step one adsorption tower, the organic impurities by adsorbing made fine to adsorbent passed through a methanol decomposition gas containing organic impurities Methanol decomposition gas by the TSA method in which the methanol adsorption gas is produced and the other adsorption tower is in the heat desorption step, and the heated methanol decomposition gas is introduced into the adsorption tower to desorb the organic impurities adsorbed on the adsorbent In the method for removing organic impurities, a methanol decomposition gas containing organic impurities discharged from the adsorption tower in the heat desorption step is introduced into the methanol absorption tower to absorb and remove a part of the organic impurities in the methanol decomposition gas. On the other hand, the first step of returning the methanol decomposition gas containing residual organic impurities discharged from the methanol absorption tower to the adsorption tower in the adsorption step A closed TSA which sequentially performs the second step of introducing an unheated methanol decomposition gas into the other adsorption tower instead of the heated methanol decomposition gas and precooling the other adsorption tower. Method for removing organic impurities in methanol decomposition gas by the method.   Following the second step, the methanol decomposition gas as the raw material is directly introduced into the other adsorption tower in the direction opposite to the gas flow of the second step to cool the adsorption tower, and the methanol discharged from the adsorption tower The method for removing organic impurities in the methanol decomposition gas by the closed TSA method according to claim 1, further comprising a third step of introducing the decomposition gas into the methanol absorption tower.   The heated methanol decomposing gas used in the heat desorption step is one in which at least part of the organic impurities has been removed in advance through the pre-adsorption tower, and the second step is followed by the other The raw material methanol decomposition gas is directly introduced into the adsorption tower in the opposite direction to the gas flow in the second step to cool the adsorption tower, and the methanol decomposition gas discharged from the adsorption tower is heated to enter the preliminary adsorption tower. The closed process according to claim 1, further comprising a third step of introducing and desorbing organic impurities in the preliminary adsorption tower by heating, and introducing the methanol decomposition gas discharged from the preliminary absorption tower into the methanol absorption tower. Removal method of organic impurities in methanol decomposition gas by TSA method.   A method of regenerating methanol having absorbed organic impurities in methanol decomposition gas in the methanol absorption tower is a gas stripping method or distillation method using off-gas after further purifying the purified methanol decomposition gas by a CO-PSA method. The method for removing organic impurities in methanol decomposition gas by the closed TSA method according to any one of claims 1 to 3, wherein

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