JP2020163304A - Gas separation recovery system and gas separation recovery method - Google Patents

Abstract

To provide a gas separation recovery system capable of energy-saving by performing efficient utilization of waste-heat.SOLUTION: A gas separation recovery system 1 includes: an adsorption tank 2 which adsorbs prescribed gas contained in gas to be treated into a gas adsorbent and discharges gas which is not adsorbed by the gas adsorbent; a regeneration tank 5 which heats the gas adsorbent and desorbs the prescribed gas from the gas adsorbent; and transfer means 9 which transfers the gas adsorbent from the adsorption tank 2 to the regeneration tank 5 and transfers the gas adsorbent passing through the regeneration tank 5 to the adsorption tank 2. A preheating tank 4 which preliminarily heats the gas adsorbent transferred from the adsorption tank 2 to the regeneration tank 5 is provided between the adsorption tank 2 and the regeneration tank 5. A preliminary cooling tank 6 which preliminarily cools the gas adsorbent transferred from the regeneration tank 5 to the adsorption tank 2 is provided behind the regeneration tank 5, and is configured such that gas is circulated between the preliminary heating tank 4 and the preliminary cooling tank 6.SELECTED DRAWING: Figure 1

Description

The present invention relates to a gas separation / recovery system that absorbs a gas such as carbon dioxide, and a gas separation / recovery method.

In recent years, the increase in carbon dioxide concentration in the atmosphere has been regarded as a problem as a cause of global warming, especially in large-scale facilities such as thermal power plants and steelworks blast furnaces that emit a large amount of carbon dioxide. There is a need to reduce carbon dioxide emissions.

As one of the methods for reducing carbon dioxide emissions, a method using a carbon dioxide separation and recovery device that absorbs carbon dioxide in the exhaust gas has been proposed. This carbon dioxide separation and recovery device is equipped with a solid carbon dioxide adsorbent, and has an adsorption step of adsorbing carbon dioxide to the carbon dioxide adsorbent by contacting it with exhaust gas at a relatively low temperature, and heating to adsorb carbon dioxide. By alternately repeating the two steps of desorbing and regenerating the carbon dioxide adsorbent, carbon dioxide in the exhaust gas can be continuously separated and recovered.

As such a conventional carbon dioxide separation / recovery device, for example, the carbon dioxide separation / recovery system described in Patent Document 1 is known. This carbon dioxide separation and recovery system has an adsorption tower that adsorbs carbon dioxide in the exhaust gas with a carbon dioxide adsorbent at a predetermined adsorption temperature and discharges the exhaust gas from which carbon dioxide has been removed, and carbon dioxide that has adsorbed carbon dioxide. It is provided with a regeneration tower that desorbs carbon dioxide from the carbon dioxide adsorbent by condensing the desorbed water vapor on the adsorbent.

Japanese Patent No. 6427098

In the above-mentioned carbon dioxide separation and recovery system, not only when a mobile layer type processing tower (adsorption tower and regeneration tower) using a carbon dioxide adsorbent as a moving layer is adopted, but also when a batch type processing tower is adopted. , Exhaust heat is generated in the process of returning the carbon dioxide adsorbent from which carbon dioxide is desorbed to a low temperature, but efficient exhaust heat utilization is not performed, and there is room for improvement in terms of saving energy in the entire system. Has been done.

An object of the present invention is to provide a gas separation / recovery system and a gas separation / recovery method capable of efficiently utilizing exhaust heat and saving energy.

The gas separation / recovery system of the present invention includes a suction tank that adsorbs a predetermined gas contained in the gas to be treated on a gas adsorbent and discharges a gas that is not adsorbed on the gas adsorbent.
A regeneration tank that heats the gas adsorbent to desorb the predetermined gas from the gas adsorbent.
In a gas separation / recovery system including a transfer means for transferring the gas adsorbent from the adsorption tank to the regeneration tank and transferring the gas adsorbent through the regeneration tank to the adsorption tank.
A preheating tank for preheating the gas adsorbent transferred from the adsorption tank to the regeneration tank is provided between the adsorption tank and the regeneration tank, and after the regeneration tank, the regeneration tank is used as described. A pre-cooling tank for pre-cooling the gas adsorbent transferred to the adsorbent tank is provided, and the gas is configured to circulate between the pre-heating tank and the pre-cooling tank.

In this configuration, a preheating tank for preheating the gas adsorbent transferred from the adsorption tank to the regeneration tank is provided between the adsorption tank and the regeneration tank, and after the regeneration tank, from the regeneration tank to the adsorption tank. It is equipped with a pre-cooling tank that pre-cools the gas adsorbent to be transferred, and is configured to circulate gas between the pre-heating tank and the pre-cooling tank. After that, the heat of the gas adsorbent is recovered by the gas in the precooling tank, the gas adsorbent is precooled, and the gas that recovers this heat is supplied to the preheating tank, which is conveyed to the preheating tank. The gas adsorbent is preheated by the heat recovered by the gas in the precooling tank. That is, the heat of the gas adsorbent after the regeneration step can be recovered, and the heat can be used as a part of the heat used in the regeneration step of the gas adsorbent to be subjected to the regeneration step, so that the entire system can be used. As a result, efficient use of waste heat is carried out, and energy saving can be achieved.

Further, the gas separation / recovery system of the present invention includes a first gas shutoff mechanism between the preheating tank and the regeneration tank, and a second gas shutoff mechanism between the regeneration tank and the precooling tank.

With this configuration, the regeneration tank can be sealed by the first gas shutoff mechanism and the second gas shutoff mechanism, so that a predetermined gas can be recovered more efficiently, and as a result, the predetermined gas can be recovered. , A predetermined gas with higher purity can be obtained.

Further, the gas separation / recovery system of the present invention includes a purge tank between the adsorption tank and the preheating tank, and supplies a part of the predetermined gas desorbed in the regeneration tank to the purge tank.

In this configuration, a purge tank is provided between the adsorption tank and the preheating tank, and a part of the predetermined gas desorbed in the regeneration tank is supplied to the purge tank, so that it is attached to the gas adsorbent. Gases other than the above-mentioned gas are eliminated, and the predetermined gas can be recovered more efficiently in the subsequent regeneration tank, and as a result, a predetermined gas having a higher purity can be obtained.

Further, in the gas separation and recovery system of the present invention, the predetermined gas is carbon dioxide.

With this configuration, it can be used to reduce the emission of carbon dioxide, which is one of the greenhouse gases, by applying it to large-scale facilities such as thermal power plants and blast furnaces of steelworks.

Further, in the gas separation / recovery system of the present invention, the gas adsorbent includes an ionic liquid and a carrier, and the ionic liquid is supported on the carrier.

With this configuration, a gas adsorbent with high gas adsorption / desorption performance can be obtained with a simple configuration.

Further, the gas separation / recovery system of the present invention is a phase-changing ionic liquid in which the ionic liquid undergoes a phase change from solid to liquid during gas absorption and from liquid to solid during gas desorption.

With this configuration, the gas adsorption / desorption performance of the gas adsorbent can be further improved.

Further, in the gas separation and recovery system of the present invention, the phase change ionic liquid is tetraethylphosphonium benzoimidazolide.

With this configuration, the gas adsorption / desorption performance of the gas adsorbent with respect to carbon dioxide can be particularly improved.

Further, in the gas separation and recovery system of the present invention, the carrier is silicon dioxide or activated carbon.

In this configuration, since the carrier is composed of a porous substance such as silicon dioxide or activated carbon, the ionic liquid is reliably supported.

The gas separation / recovery method of the present invention includes an adsorption step of adsorbing a predetermined gas contained in the gas to be treated on the gas adsorbent and discharging the gas not adsorbed on the gas adsorbent.
In a gas separation / recovery method including a regeneration step of heating the gas adsorbent to which the predetermined gas is adsorbed through the adsorption step to desorb the predetermined gas from the gas adsorbent.
After the regeneration step, a pre-cooling step of recovering heat by gas from the gas adsorbent from which the predetermined gas has been desorbed through the regeneration step and pre-cooling the gas adsorbent is performed.
The gas adsorbent to which the predetermined gas is adsorbed through the adsorption step is subjected to the pre-cooling step performed on the gas adsorbent that has undergone the regeneration step before the gas adsorbent by the heat recovered by the gas. The preheating step of preheating is performed before the regeneration step.

In this configuration, a pre-cooling step of recovering heat from the gas adsorbent to which a predetermined gas has been desorbed through the regeneration step by a gas and pre-cooling the gas adsorbent is performed after the regeneration step, and the adsorption step is performed. The regeneration step is a preheating step in which the gas adsorbent to which a predetermined gas is adsorbed is preheated by the heat recovered by the gas in the precooling step performed on the gas adsorbent that has undergone the regeneration step before the gas adsorbent. Because the heat of the gas adsorbent after the regeneration process is recovered and the heat is used as a part of the heat used in the regeneration process of the gas adsorbent to be subjected to the next regeneration process. , Efficient use of exhaust heat is carried out, and energy saving can be achieved.

It is a schematic block diagram of a gas separation recovery system.

[Embodiment]
Hereinafter, embodiments of the present invention will be described.
(Gas separation and recovery system)
As shown in FIG. 1, the gas separation / recovery system 1 of the present embodiment includes an adsorption tank 2, a purge tank 3, a preheating tank 4, a regeneration tank 5, a precooling tank 6, and a first air lock mechanism 7 (first gas). An example of a shutoff mechanism), a second air lock mechanism 8 (an example of a second gas shutoff mechanism), a conveyor 9 (an example of a transfer means), a dehumidifier 10, a blower 11, and a vacuum pump 12.

The gas separation / recovery system 1 includes a preheating tank 4 for preheating the gas adsorbent transferred from the adsorption tank 2 to the regeneration tank 5 between the adsorption tank 2 and the regeneration tank 5, and is provided after the regeneration tank 5. A pre-cooling tank 6 for pre-cooling the gas adsorbent transferred from the regeneration tank 5 to the adsorbent tank 2 is provided, and the gas is configured to circulate between the pre-heating tank 4 and the pre-cooling tank 6. ing. Further, a first airlock mechanism 7 is provided between the preheating tank 4 and the regeneration tank 5, and a second airlock mechanism 8 is provided between the regeneration tank 5 and the precooling tank 6. Further, a purge tank 3 is provided between the adsorption tank 2 and the preheating tank 4. An airlock mechanism (not shown) is also provided between the adsorption tank 2 and the purge tank 3 and between the purge tank 3 and the preheating tank 4.

The first airlock mechanism 7, the second airlock mechanism 8, the purge tank 3, the dehumidifier 10, the blower 11, and the vacuum pump 12 may be provided as needed.

In the gas separation and recovery system 1, the gas adsorbent that adsorbs and desorbs a predetermined gas contained in the gas to be processed is an adsorption tank 2, a purge tank 3, a preheating tank 4, a regeneration tank 5, and a precooling tank 6. Then, in the order of returning to the adsorption tank 2, a predetermined amount is conveyed by the conveyor 9 and circulated. When the predetermined treatment is performed in each tank 2, 3, 4, 5, 6, the conveyor 9 stops the transportation of the gas adsorbent, and each tank 2, 3, 4, 5 The space between, and 6 is closed by the airlock mechanism.

A gas supply line 13 to be processed and a first off-gas discharge line 14 are connected to the adsorption tank 2. In the adsorption tank 2, the gas to be processed is supplied through the gas supply line 13 to be processed, and the predetermined gas contained in the gas to be processed is adsorbed by the gas adsorbent and is not adsorbed by the gas adsorbent. (Hereinafter, this gas is referred to as off-gas) is discharged from the first off-gas discharge line 14.

A dehumidifier 10 is provided in the gas supply line 13 to be treated, and the gas to be treated is cooled to a certain extent and dehumidified. When natural gas combustion exhaust gas is used as the gas to be treated, LNG cooling heat may be used to cool the gas to be treated.

The second off-gas discharge line 15 and the refined gas supply line 16 are connected to the purge tank 3. In the purge tank 3, the gas adsorbent conveyed from the adsorption tank 2 by the conveyor 9 is purged by using a part of a predetermined gas (hereinafter, this gas is referred to as a refined gas) desorbed from the regeneration tank 5. The process is carried out. By supplying a part of the refined gas through the refined gas supply line 16, a gas other than the predetermined gas attached to the gas adsorbent, for example, nitrogen oxide (NOx), sulfur oxide (SOx), etc. Is discharged from the second off-gas discharge line 15.

A circulation line 17 is connected to the preheating tank 4 so that gas circulates with the precooling tank 6. A blower 11 is provided on the circulation line 17. In the preheating tank 4, the gas adsorbent conveyed from the purge tank 3 by the conveyor 9 is preheated by the hot gas of the gas adsorbent after the regeneration step.

The regeneration tank 5 is an external heat type regeneration tank 5 made of a heat-resistant material, and steam of 150 ° C. or lower is used for heating, for example. A refined gas discharge line 18 is connected to the regeneration tank 5, and a vacuum pump 12 is provided in the refined gas discharge line 18. When the gas adsorbent that has adsorbed the predetermined gas is conveyed into the regeneration tank 5, the first airlock mechanism 7 and the second airlock mechanism 8 are closed. Then, for example, the gas adsorbent is heated at a predetermined temperature while the inside of the regeneration tank 5 is depressurized by the vacuum pump 12 to less than the partial pressure of the predetermined gas contained in the gas to be processed. As a result, the predetermined gas is desorbed from the gas adsorbent, discharged from the refined gas discharge line 18, and recovered. A refined gas supply line 16 is connected to the refined gas discharge line 18, and a part of the refined gas is used for the purging process in the purge tank 3.

A circulation line 17 is connected to the pre-cooling tank 6 so that gas circulates with the pre-heating tank 4. As a result, the pressure and temperature in the pre-cooling tank 6 become equal to the pressure and temperature in the preheating tank 4. When the step of regenerating the gas adsorbent is completed, the first airlock mechanism 7 and the second airlock mechanism 8 are opened, and the gas adsorbent is conveyed to the precooling tank 6 for precooling. That is, the heat of the gas adsorbent after the regeneration step in the regeneration tank 5 is recovered by the gas flowing through the circulation line 17, the gas adsorbent is cooled, and the gas recovered from this heat is supplied to the preheating tank 4. The pre-cooled gas adsorbent is conveyed to the adsorption tank 2 again by the conveyor 9.

(Gas separation and recovery method)
In the gas separation / recovery method of the present embodiment, a predetermined gas contained in the gas to be treated is adsorbed on the gas adsorbent, and the gas not adsorbed on the gas adsorbent is discharged, and a predetermined gas is adsorbed through the adsorption step. A purge step of purging the gas adsorbent on which the gas is adsorbed, a regeneration step of desorbing a predetermined gas from the gas adsorbent that has undergone the purge step, and a preliminary heating of the gas adsorbent that is performed before the regeneration step. It includes a heating step and a precooling step performed after the regeneration step to precool the gas adsorbent. The purging step may be carried out as needed.

The adsorption step is carried out in the adsorption tank 2. The gas to be processed that is supplied via the gas supply line 13 to be processed comes into contact with the gas adsorbent that has been conveyed into the adsorption tank 2 by the conveyor 9, and the predetermined gas contained in the gas to be processed is the gas adsorbent. Is adsorbed on. When the predetermined gas is carbon dioxide, for example, it may be carried out for a predetermined time under atmospheric pressure (10.13 × 10 ⁴ Pa) of 40 ° C. to 50 ° C. The gas adsorbent that has completed the adsorption step is conveyed to the purge tank 3 by the conveyor 9.

The purging step is carried out in the purging tank 3. For example, a purging process may be carried out using a part of the purified gas obtained in the regeneration step. The purging step removes a gas other than the predetermined gas attached to the gas adsorbent. When the predetermined gas is carbon dioxide, for example, it may be carried out for a predetermined time under atmospheric pressure (10.13 × 10 ⁴ Pa) of 40 ° C. to 50 ° C.

The preheating step is carried out in the preheating tank 4. As the heat source for preheating, the heat of the gas adsorbent after the regeneration step is used. In the present embodiment, the gas adsorbent is preheated by the hot gas of the gas adsorbent after the regeneration step. When the predetermined gas is carbon dioxide, for example, under a pressure of about 5.9 × 10 ⁴ Pa, the gas adsorbent becomes an intermediate temperature (55 ° C. to 70 ° C.) between the temperature of the adsorption process and the temperature of the regeneration process. It is good to carry out for a predetermined time.

The regeneration step is carried out in the regeneration tank 5. In the regeneration step, the gas adsorbent may be heated at, for example, 150 ° C. or lower in a state where the inside of the regeneration tank 5 is depressurized to less than the partial pressure of the predetermined gas contained in the gas to be treated. If the predetermined gas is carbon dioxide, for example, 70 ° C. to 90 ° C., it may be carried out 1.0 × ¹⁰ 4 Pa predetermined time under a pressure of.

The pre-cooling step is carried out in the pre-cooling tank 6. The pre-cooling step is performed by recovering the heat of the gas adsorbent after the regeneration step with a gas, and the heat recovered in the pre-cooling step is used in the preheating step. Specifically, in the present embodiment, heat is recovered by a gas from a gas adsorbent to which a predetermined gas has been desorbed through a regeneration step, the gas adsorbent is pre-cooled, and the heat recovered by this gas is generated. , The gas adsorbent used in the preheating step currently performed in the preheating tank 4 is regenerated before the gas adsorbent used in the preheating step in the preheating tank 4. After the process, the gas adsorbent provided in the pre-cooling step in the pre-cooling tank 6 is heated by the heat of the gas adsorbent. In the pre-cooling step, when the predetermined gas is carbon dioxide, for example, under a pressure of about 5.9 × 10 ⁴ Pa, the gas adsorbent has an intermediate temperature (55 ° C.) between the temperature of the adsorption step and the temperature of the regeneration step. It is preferable to carry out for a predetermined time until the temperature reaches ~ 70 ° C.). The pre-cooled gas adsorbent is transferred to the adsorption process again by the transfer process.

(Gas to be processed and gas to be recovered)
Examples of the gas to be treated by the gas separation / recovery system 1 of the present embodiment include industrial exhaust gas emitted from a thermal power plant, a steel mill blast furnace, an automobile, and the like. In particular, as the gas emitted from the thermal power plant, for example, natural gas combustion exhaust gas (100 ° C., 101.3 kPa, 3.9% by volume CO ₂ , steam saturation, about 5 ppm NOx), coal combustion exhaust gas (50). ℃, 101.3 kPa, 14% by volume CO ₂ , water vapor saturation, about 20 ppm NOx, about 30 ppm SOx).
Further, examples of the predetermined gas recovered from the gas to be treated include carbon dioxide, carbon monoxide, hydrocarbons and the like, and carbon dioxide is preferable.

(Gas adsorbent)
As the gas adsorbent applicable to the gas separation / recovery system 1 of the present embodiment, for example, it is desirable that the gas adsorbent includes an ionic liquid and a carrier, and the ionic liquid is supported on the carrier.

Suitable ionic liquids include phase-changing ionic liquids that undergo a phase change from solid to liquid during gas absorption and from liquid to solid during gas desorption. In particular, when the gas to be recovered is carbon dioxide, it is desirable that the phase change ionic liquid is tetraethylphosphonium benzoimidazolide (P2Bn). Suitable carriers include silicon dioxide and activated carbon, which are porous substances.

The present invention can be suitably used in the field of technology relating to a gas separation / recovery system that absorbs a gas such as carbon dioxide.

1 Gas separation and recovery system 2 Adsorption tank 3 Purge tank 4 Preheating tank 5 Regeneration tank 6 Pre-cooling tank 7 1st airlock mechanism 8 2nd airlock mechanism 9 Conveyor (example of transfer means)
10 Dehumidifier 11 Blower 12 Vacuum pump 13 Processed gas supply line 14 1st off gas discharge line 15 2nd off gas discharge line 16 Purified gas supply line 17 Circulation line 18 Purified gas discharge line

Claims (9)

A suction tank that adsorbs a predetermined gas contained in the gas to be processed to a gas adsorbent and discharges a gas that is not adsorbed by the gas adsorbent.
A regeneration tank that heats the gas adsorbent to desorb the predetermined gas from the gas adsorbent.
In a gas separation / recovery system including a transfer means for transferring the gas adsorbent from the adsorption tank to the regeneration tank and transferring the gas adsorbent through the regeneration tank to the adsorption tank.
A preheating tank for preheating the gas adsorbent transferred from the adsorption tank to the regeneration tank is provided between the adsorption tank and the regeneration tank, and after the regeneration tank, the regeneration tank is used as described. A gas separation and recovery system including a pre-cooling tank for pre-cooling the gas adsorbent transferred to the adsorption tank, and configured to circulate gas between the pre-heating tank and the pre-cooling tank. The gas separation / recovery system according to claim 1, further comprising a first gas shutoff mechanism between the preheating tank and the regeneration tank, and a second gas shutoff mechanism between the regeneration tank and the precooling tank. The gas separation and recovery according to claim 1 or 2, wherein a purge tank is provided between the adsorption tank and the preheating tank, and a part of the predetermined gas desorbed in the regeneration tank is supplied to the purge tank. system. The gas separation and recovery system according to any one of claims 1 to 3, wherein the predetermined gas is carbon dioxide. The gas separation / recovery system according to any one of claims 1 to 4, wherein the gas adsorbent comprises an ionic liquid and a carrier, and the ionic liquid is supported on the carrier. The gas separation and recovery system according to claim 5, wherein the ionic liquid is a phase-changing ionic liquid in which the phase changes from solid to liquid when gas is absorbed and from liquid to solid when gas is desorbed. The gas separation and recovery system according to claim 6, wherein the phase change ionic liquid is tetraethylphosphonium benzoimidazolide. The gas separation and recovery system according to any one of claims 5 to 7, wherein the carrier is silicon dioxide or activated carbon. An adsorption step in which a predetermined gas contained in the gas to be processed is adsorbed on a gas adsorbent and the gas not adsorbed on the gas adsorbent is discharged.
In a gas separation / recovery method including a regeneration step of heating the gas adsorbent to which the predetermined gas is adsorbed through the adsorption step to desorb the predetermined gas from the gas adsorbent.
After the regeneration step, a pre-cooling step of recovering heat by gas from the gas adsorbent from which the predetermined gas has been desorbed through the regeneration step and pre-cooling the gas adsorbent is performed.
The gas adsorbent to which the predetermined gas has been adsorbed through the adsorption step is subjected to the pre-cooling step performed on the gas adsorbent that has undergone the regeneration step before the gas adsorbent by the heat recovered by the gas. A gas separation / recovery method in which a preheating step of preheating is performed before the regeneration step.

Images