KR101433036B1 - Temperature and pressure swing moving bed adsorption system - Google Patents

Abstract

The present invention relates to an adsorption process system for selective gas separation using stepwise desorption, comprising: an adsorption bed for selectively adsorbing an introduced gas mixture; A blower installed at a lower portion of the adsorption bed to inject the mixed gas; A high temperature desorbing bed disposed below the adsorbing bed to desorb the adsorbent primarily by heating the adsorbent conveyed through the lower part of the adsorbing bed; A desorbent bed desorbed from the high-temperature desorbent bed to desorb the adsorbent powder which is desorbed from the desorbent bed, the desorbent bed being located below the high-temperature desorbent bed; A transfer device for transferring the adsorbent powder desorbed from the desorbent bed to the adsorbent bed; And the cooling water is introduced into the lower part of the lower part of the adsorption bed to remove heat, the cooling water to be discharged is separated, the separated cooling water is again introduced into the lower part of the lower part of the absorption bed to remove heat, Wherein the high temperature desorption bed is the same as the pressure (P _A ) of the adsorption bed, and the desorption bed is connected to the adsorption bed Is maintained at a low pressure (P _D ) and a high temperature (T _D ).
According to the present invention as described above, it is not necessary to take into consideration that the gas in the adsorption bed flows back due to the pressure difference generated in the reflux pipe, so that it is possible to realize a small-scale apparatus and to operate under an efficient fixed condition, Therefore, it is possible to obtain higher productivity as compared with other gas separation apparatuses of the same size, and it is possible to operate the pressure fluctuation and the temperature fluctuation operation under the desired conditions, thereby enabling efficient operation and saving energy. It can be optimized. It can also be applied to the separation of various types of gas mixtures.

Description

TECHNICAL FIELD [0001] The present invention relates to a mobile phase temperature pressure swing adsorption process system for gas separation,

The present invention relates to a specific gas adsorption process system, and more particularly, to a gas adsorption process system for adsorbing gas from an adsorbent by employing a heat exchange system capable of adsorption and stepwise high-low pressure desorption and optimization of adsorption performance and economical efficiency in different temperature and pressure environments. Phase adsorption process system for selective gas separation by separating and circulating adsorbent in a mobile phase.

The adsorption process has been widely applied to the separation and purification of gases especially in the process of separating the adsorbent by using the equilibrium adsorption amount of the gas or liquid for each component. Separation of oxygen in the air, separation of high purity hydrogen from petrochemical plants, separation of normal paraffin and isoparaffin, separation of methane contained in anaerobic fermentation gas, removal or separation of volatile organic compounds in industrial environment are typical applications . In recent years, adsorption processes have been studied for the purpose of recovering carbon dioxide, which is the main cause of global warming, from the combustion exhaust gas of large-scale industrial processes such as power plants and steel mills.

Adsorbents used for gas separation include zeolite, molecular sieve, activated carbon, carbon molecular sieve, silica gel, activated alumina, etc. In the adsorption process, due to many pores, adsorbent having a large surface area, Van der Waals) is the application of the physical adsorption which is attached by the force. This is because the adsorption amount of physical adsorption may be smaller than that of chemisorption, but the bonding force is relatively low and desorption is easy.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing the relationship between the amount of gas adsorbed on an adsorbent and the partial pressure of one component in a general mixed gas by adsorption isotherms. FIG. As shown in FIG. 1, the physical adsorption amount of a certain gas component increases as the partial pressure of the component increases and as the temperature decreases, and the adsorption separation process is configured using this principle.

Conventionally, pressure swing adsorption (PSA) method has been used most often for gas separation using adsorption. This process basically performs separation and purification at a short period of time by switching the pressurization, high pressure adsorption, depressurization discharge, depressurization or modification thereof in one adsorption tower at a short period of time. On the other hand, a temperature swing adsorption (TSA) method in which the equilibrium adsorption amount varies depending on the temperature is used, and a pressure temperature swing adsorption (PTSA) method in which the two are mixed is also used. These are all operated in such a manner that the adsorption step and the desorption step are periodically repeated, and the desorbed components are recovered and commercialized as needed.

In the recovery of VOC, a temperature fluctuation adsorption process (TSA) using a mobile phase is frequently used (see FIG. 2). The concept of the mobile phase is similar to the process of adsorbing the mobile phase temperature fluctuation of the present invention. However, since one bed is used, the adsorption part and the desorption part have the same pressure, which results in poor adsorption and desorption efficiency.

Temperature swing adsorption (TSA) As shown in FIG. 1, the adsorption tower is heated at a temperature (T _L , q _ads ) at a constant pressure to set the temperature to (T _H , q _des ) The method of desorption is temperature fluctuation adsorption. The most convenient way to raise the temperature in the temperature swing process is to purify the adsorbent with the preheated gas, but it is not easy to raise or lower the temperature of the adsorbent in a short time. Therefore, the temperature swing adsorption may use a mobile adsorption apparatus, This method is also adopted in the removal of volatile organic compounds by using carbon.

The temperature swing adsorption process has a bed, and it is repeatedly operated in a short cycle (glass at low temperature) and desorption (glass at high temperature) in a short period of about 1 minute. Due to the thermal mass of the adsorbent, It is very difficult to change the temperature in cycles. In addition, there is a disadvantage that heating and cooling the bed having a large thermal mass in a short period of time is expensive.

Pressure swing adsorption (PSA) is desorbed by depressurizing the pressure from (P _H , q _ads ) to a low pressure (P _L , q _des ) without applying heat as shown in FIG. The method is pressure swing adsorption. The cycle time of pressure swing adsorption compared to temperature swing adsorption is usually as short as several minutes or a few seconds since rapid pressure reduction is possible. The basic steps of the pressure swing adsorption process are raw pressurization, adsorption, depressurization and washing steps ).

In order to increase the efficiency of the process, new steps such as product pressurization, cocurrent decompression, pressure equalization, vacuum desorption, and strong adsorptive purification steps have been added. Currently, most pressure swing adsorption processes consist of a combination of these steps. However, the pressure swing adsorption is placed in a continuous dynamic state because the operation of the various modes is switched in series, resulting in a severe change in the gas flow rate. As a result, the operating point of gas pumps, such as blowers, compressors, and vacuum pumps, can not be fixed in the high-efficiency zone and moves between the low-efficiency and high-efficiency zones so that in the case of high-volume gas treatment, such as separating carbon dioxide from the exhaust gas from the power plant, The operation cost can be a large burden.

In addition, in the conventional pressure swing adsorption process, the flow rate into the bed is proportional to the difference between the pressure at the bed inlet and the pressure inside the bed. When the gas is injected into the bed for adsorption, the gas at the first flow rate is low due to the low pressure of the bed. However, as time passes and the pressure of the bed gradually increases, the flow rate of the gas introduced into the bed gradually decreases . As a result, the operating conditions under which the pump operates vary with time.

When the vacuum is taken out of the bed through a vacuum pump for desorption, the gas flows at a high flow rate at first when the pressure is reduced. However, as time passes and the pressure of the bed becomes lower, the flow rate of the gas flowing out from the bed becomes smaller. As a result, the operating conditions under which the pump operates vary with time. In addition, the efficiency of the pump varies depending on the operating conditions. Therefore, when the operating conditions are changed as in the above-described adsorption and desorption processes, it is difficult to always operate the pump with the maximum efficiency, thereby consuming a lot of operation costs.

The power required for the pressurization (or depressurization) in the operation cost of the adsorption process takes up most of the power required for the pump. As a result, the disadvantages described above result in a large operating cost.

3 is a process flow diagram of a conventional improved fluidized bed adsorber. The apparatus is composed of an adsorption section, a desorption section, an activated carbon conveyance section, a solvent separation section, and the like. The adsorption part is a multi-stage porous plate composed of a moving part and a lower part of activated carbon. Activated carbon forms a fluidized bed on the porous plate by the solvent-containing gas rising from the bottom to adsorb the solvent. Then, the amount of activated carbon flowing down from the lower part to the lower part of the perforated plate corresponds to the amount of circulation. The desorption section mainly uses a multi-tube heat exchanger.

The activated carbon flowing down from the adsorption part is in contact with the desorbed gas in the lower part of the tube which is heated in the heat exchanger. The desorbing gas is discharged from the upper portion of the desorbing portion containing the desorbed solvent to the solvent separating portion. On the other hand, the activated carbon desorbed from the solvent is conveyed to the perforated plate at the uppermost stage of the adsorption unit through the air flow conveyance pipe at the lowermost part of the desorption unit. Through this process, the activated carbon repeats adsorption and desorption while continuously circulating.

The most important feature of this apparatus is that since the adsorbing portion and the desorbing portion are separated from one bed and that the desorbing gas such as steam, air, nitrogen and the like is freely selected because of the indirect heating and desorbing method, There is a disadvantage that it is operated under the same pressure.

In the conventional adsorption process system, sufficient heat removal is required to increase the adsorption performance. Therefore, the cooling water flowing into the adsorption bed is used for increasing the flow rate. However, since the outlet temperature of the cooling water must be high in order to increase or optimize economy, There is a problem that the flow rate must be reduced.

In order to solve the above-mentioned problems, first, the adsorption process is a continuous process, and the gas pumps can be operated under a fixed condition, and each of the pumps can be operated under the operating conditions with the maximum efficiency. To achieve higher productivity in the same scale of equipment, and thirdly, to be able to perform pressure fluctuation and temperature fluctuation operation under desired conditions, and fourth, And to improve the operation efficiency of the pump to reduce the operation cost and to improve the separation and recovery efficiency of the mixed gas. Fifth, by using the heat exchange system, energy required for each stage is reduced and low cost operation is enabled. This is to achieve optimization at the same time.

In addition, the present invention is intended to provide a process system that can be applied to various kinds of gas mixture separation, for example, in a one-step concentration process for separating a large amount of gas such as carbon dioxide from a combustion exhaust gas.

According to a first aspect of the present invention, there is provided an adsorbing apparatus for adsorbing an introduced mixed gas, A blower installed at a lower portion of the adsorption bed to inject the mixed gas; A high temperature desorbing bed disposed below the adsorbing bed to desorb the adsorbent primarily by heating the adsorbent conveyed through the lower part of the adsorbing bed; A desorbent bed desorbed from the high-temperature desorbent bed to desorb the adsorbent powder which is desorbed from the desorbent bed, the desorbent bed being located below the high-temperature desorbent bed; A transfer device for transferring the adsorbent powder desorbed from the desorbent bed to the adsorbent bed; And the cooling water is introduced into the lower part of the lower part of the adsorption bed to remove heat, the cooling water to be discharged is separated, the separated cooling water is again introduced into the lower part of the lower part of the absorption bed to remove heat, Wherein the high temperature desorption bed is the same as the pressure (P _A ) of the adsorption bed, and the desorption bed is connected to the adsorption bed (P _D ) and at a higher temperature (T _D ) than the temperature

Here, the heat exchange system may be configured such that the cooling water is introduced into the lower part of the lower part of the adsorption bed to remove heat and the first cooling water in which a part of the cooling water is separated is introduced into the upper part of the lower end of the absorption bed, A first heat exchanger for introducing the cooling water into the high-temperature desorption bed to raise the temperature of the desorption bed, and a second cooling water for partially separating the cooling water discharged from the lower part of the absorption bed, and the remaining third cooling water is heated, And a second heat exchanger for increasing the temperature of the desorbent bed.

Preferably, the third cooling water and the fourth cooling water, which are discharged from the adsorption bed and flow into the high temperature desorption bed, may be heated by at least one steam heater provided in each flow path, and the third cooling water may be heated The steam heater may include a steam heater using waste gas discharged from the upper end of the adsorption bed.

In addition, it is preferable that the injection part from which the adsorbent is introduced from the desorbent bed has a double-layer structure, and the adsorbent bed is divided into an upper space and a lower space by the inner space of the adsorbent bed occupied by the adsorbent, And the mixed gas is injected into the upper end of the adsorption bed.

According to a second aspect of the present invention, there is provided an adsorbing apparatus comprising: an adsorption bed for selectively adsorbing an introduced mixed gas; A compressor installed under the adsorption bed for compressing and injecting the mixed gas; A high temperature desorbing bed disposed below the adsorbing bed to desorb the adsorbent primarily by heating the adsorbent conveyed through the lower part of the adsorbing bed; A desorbent bed desorbed from the high-temperature desorbent bed to desorb the adsorbent powder which is desorbed from the desorbent bed, the desorbent bed being located below the high-temperature desorbent bed; A transfer device for transferring the adsorbent powder desorbed from the desorbent bed to the adsorbent bed; And the cooling water is introduced into the lower part of the lower part of the adsorption bed to remove heat, the cooling water to be discharged is separated, the separated cooling water is again introduced into the lower part of the lower part of the absorption bed to remove heat, Wherein the high temperature desorption bed is the same as the pressure (P _A ) of the adsorption bed, and the desorption bed is connected to the adsorption bed (P _D ) and at a higher temperature (T _D ) than the temperature

Here, the heat exchange system may be configured such that the cooling water is introduced into the lower part of the lower part of the adsorption bed to remove heat and the first cooling water in which a part of the cooling water is separated is introduced into the upper part of the lower end of the absorption bed, A first heat exchanger for introducing the cooling water into the high-temperature desorption bed to raise the temperature of the desorption bed, and a second cooling water for partially separating the cooling water discharged from the lower part of the absorption bed, and the remaining third cooling water is heated, And a second heat exchanger for increasing the temperature of the desorbent bed.

The third cooling water and the fourth cooling water, which are discharged from the adsorption bed and flow into the high temperature desorption bed, are preferably heated by at least one steam heater provided in each flow path, and the steam heater for heating the third cooling water And a steam heater using waste gas discharged from the upper end of the adsorption bed.

In addition, preferably, the injection part through which the adsorbent is introduced from the desorption bed may be a double-layered structure, and the adsorption bed may be divided into an upper space and a lower space by the inner space of the adsorption bed occupied by the adsorbent, And the mixed gas may be injected into the upper end of the adsorption bed.

According to the present invention, it is possible to increase the operation efficiency of the system and increase the efficiency of separation and recovery of the gas mixture by using the stepwise desorption. Further, since it is possible to operate under an efficient fixed condition and continuous operation is possible, it is possible to obtain higher productivity as compared with other gas separation apparatuses of the same size, and it is possible not only to perform pressure fluctuation and temperature fluctuation operation under desired conditions, By using the system, it is possible to reduce energy consumption at each stage and to operate at a low cost, so that efficient operation can be achieved, and energy savings can be achieved, thereby improving adsorption performance and economical efficiency.

In addition, it is possible to select a gas pump with high efficiency at the operating point or at the operating point where the gas pump can operate at a high efficiency, a temperature swing to operate at different temperatures for each process, The present invention is advantageous in that the backflow of the gas is prevented and the heat integration of the entire system is facilitated.

In addition, it can be applied to the separation of various kinds of gas mixtures, and is particularly useful for a one-step concentration process for separating a large amount of gas such as carbon dioxide from a combustion exhaust gas.

The process of the present invention is an alternative to the pressure swing adsorption process, which is currently widely used in commercial gas adsorption and separation processes. It is a process for drying gas, recovering hydrogen from steam reformed gas, Separation, recovery of argon from the ammonia cleaning gas, recovery of CO from the exhaust gas from the steel mill, recovery of CH ₄ and CO ₂ from the landfill gas, and so on. It is possible to obtain higher productivity and higher quality products than other gas separators of the same size by operating, and it is possible to operate pressure fluctuation and temperature fluctuation under desired conditions.

Particularly, it can be said that it is especially useful for the first stage carbon dioxide concentration process which accounts for 70% of energy consumption in the existing two-stage pressure swing adsorption process used for separating and recovering carbon dioxide from a flue gas having a low partial pressure of carbon dioxide. Thus, the present invention provides a wide range of research opportunities in various researches such as absorption technology, adsorption bed technique, membrane separation technology, etc. in the present study mainly focusing on absorption technology in relation to reduction, separation and recovery of carbon dioxide And will ultimately become a catalyst for further development of the current adsorption separation technology.

1 is a graph showing adsorption isotherms showing the relationship between the partial pressure of a gas component and the adsorbed amount,
2 is a process flow chart of a conventional pressure swing adsorption process,
3 is a process flow diagram of a conventional improved fluidized bed adsorber,
4 is a diagram illustrating a configuration of an adsorption process system according to an embodiment of the present invention,
FIG. 5 is a schematic view of a cooling water flow of a new heat exchange system in a temperature and pressure mobile phase adsorption process system according to an embodiment of the present invention,
FIG. 6 is a graph showing a temperature gradient for the structure of a heat exchange system in a temperature and pressure mobile phase adsorption process system according to an embodiment of the present invention,
FIG. 7 is a view showing a change in the temperature of the cooling water through the design of the heat exchange system of the temperature and pressure mobile phase variation adsorption process system according to the embodiment of the present invention obtained through the computer simulation simulator and a change in the cooling water temperature in the conventional heat exchange system design,
8 is a graph showing an adsorption amount curve according to temperature pressure fluctuation,
9 is a view showing the heat required for cooling / heating the heat exchanging process of the system according to the present invention,
10 is a diagram illustrating a configuration of an adsorption process system according to another embodiment of the present invention,
11 is a view showing an example of the structure of an injection part of an adsorption bed in which an adsorbent is transferred from a desorption bed in the adsorption process system according to the present invention,
FIG. 12 is a flow chart of the gas mixture and the adsorbent in the mobile phase temperature pressure swing adsorption process during the operation of the adsorption / desorption process system using the stepwise desorption shown in FIGS. 4 and 11. FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

FIGS. 4 and 10 illustrate a structure of an adsorption process system according to an embodiment of the present invention. FIG. 4 illustrates a process system in which adsorption proceeds at normal pressure and desorption proceeds in vacuum. FIG. A process system in which adsorption proceeds and desorption is carried out at normal pressure is exemplified. This is because the adsorption and desorption must be smoothly carried out in order to separate the material with a high purity, and the pressure at the adsorption must be higher than the pressure at the desorption.

As shown in FIG. 4, the mobile phase temperature and pressure swing adsorption process system for gas separation according to the present invention comprises a adsorption bed 4 for selectively adsorbing an introduced mixed gas; A blower 10 mounted under the adsorption bed 4 to inject the mixed gas; A high temperature desorbing bed (30) located below the adsorbing bed to desorb the adsorbed material by heating the adsorbent conveyed through the lower part of the adsorbing bed (4); A desorbent bed (5) disposed below the high temperature desorbent bed (30), desorbed from the high temperature desorbent bed (30) to desorb the adsorbent powder which is desorbed secondarily; A transfer device (6) for transferring the adsorbent powder desorbed from the desorbent bed (5) to the adsorbent bed (4); And the lower part of the lower part of the adsorption bed (4), and the lower part of the lower part of the adsorption bed (4) And a heat exchange system that heats the cooling water discharged from the lower portion and flows into the high temperature desorption bed (30) to increase the temperature of the high temperature desorption bed (30), wherein the high temperature desorption bed (30) (P _a) and the same, and the removable bed (5) is characterized in that it is kept at a low pressure (P _D) and a temperature (T _D) as compared to the adsorbent bed (4).

Here, when the flow rate of the gas mixture is large, such as the exhaust gas of the factory, it is extremely difficult to pressurize and pressurize the gas mixture into the adsorption bed 4, so that the blower 10 The gas mixture is injected into the adsorption bed 4 at atmospheric pressure and is firstly recovered in the high temperature desorption bed 30 of the same pressure so that the adsorption bed 4 and the adsorption bed 5, In the second step.

If the flow rate of the gas mixture to be treated is not large, it is possible to use a gas mixture as the compressor 10 ', as in the process according to the process system illustrated in FIG. 10, By pressurizing and injecting into the adsorption bed 4, the process can be configured at a high pressure.

4, the gas mixture 1 is first supplied to the adsorption bed 4 through the blower 10, passes through the adsorption bed 4 and is adsorbed on the adsorbent in a large amount, After the dust is removed through the clone 11 and the bag filter 12, it is discharged to the weakly adsorbent-concentrated gas 2.

At this time, it is preferable that the velocity of the gas in the adsorption bed 4 is maintained at an initial fluidization speed so that the adsorbent flows well to the lower part of the adsorption bed 4 and at the same time the adsorbent powder is not mixed excessively. The adsorbent flowing down to the lower part of the adsorption bed 4 in a state of strongly adsorbing strong adsorbates is fed to the high temperature desorbing bed 30 located at the lower part through the feed pipe and injected. Since the adsorption bed 4 is at a higher position than the high-temperature desorption bed 30 and the pressure is the same, the adsorbent flows to the high-temperature desorption bed 30 due to gravity.

The high temperature desorbent bed 30 is a device for desorbing the adsorbent by applying heat to the desorbent bed 4 and is disposed between the adsorbent bed 4 and the desorbent bed to provide a stepwise It is a device for desorption. The temperature of the high temperature desorbing bed 30 is equal to the pressure P _A of the adsorbing bed 4 and is kept equal to or higher than the temperature T _D of the desorbing bed 5.

The primary desorption process through the high-temperature desorption bed 30 can reduce the cost of operating the pump for low-pressure or vacuum in the conventional desorption bed and can increase the CO ₂ recovery rate through the stepwise desorption do.

That is, a device for performing a process of recovering a gas such as CO ₂ through a temperature fluctuation desorption in a high-temperature desorption bed (30) in a desorption bed (5) after a primary recovery, wherein the power of the low pressure pump The heat source necessary for the high temperature desorbing bed 30 can be obtained by itself in the process and can be provided with an efficient system for additionally supplying the required heat source.

The adsorption bed 4 has a structure in which the inner space of the adsorption bed occupied by the adsorbent is divided into an upper end and a lower end and an area of the vertical section of the lower end is smaller than the upper end area, And the mixed gas is injected into the upper portion. (Not shown)

That is, in order to prevent the mixed gas or gas mixture 1 injected into the adsorption bed 4 from flowing down or leaking due to the gravity due to the high position of the adsorption bed 4, The space of the bed 4 is formed into a multi-stage structure of an upper end and a lower end, and a cross-sectional area of a lower end portion is made smaller, and the mixed gas is injected into the upper end portion. This is because the lower end portion has a smaller cross-sectional area and the inner pressure is higher than the upper end portion. Therefore, when the mixed gas is injected into the upper end portion, the mixed gas can be prevented from flowing down or leaking downward.

Hereinafter, the structure and operation of the heat exchange system will be described in detail with reference to FIGS. 4 and 10 as a structure of an adsorption process system for gas separation according to an embodiment of the present invention.

In order to simultaneously satisfy ① adsorption performance and ② economical efficiency of the adsorption process, in the embodiment of the present invention, the heat exchange method of the cooling water in the adsorption bed 4 is proposed as follows.

(1) Adsorption performance: Since it is greatly influenced by sufficient heat removal in the adsorption bed (4), the adsorption performance is maximized when sufficient heat removal is carried out through the cooling water in the adsorption bed (4) Conversely, if the adsorption bed is operated at a high temperature, the adsorption performance is not good because the equilibrium adsorption amount is high.

(2) Optimization of economy: In order to maximize the heat exchange efficiency through the heated cooling water obtained at the outlet of the adsorption bed 4, the cooling water must be heated to the maximum temperature in the adsorption bed 4, (It is assumed that the cooling water used for the heat exchange is not vaporized at 100 ^° C but exists in the liquid state by mixing the high-boiling materials.)

Since sufficient heat removal is required to satisfy the above condition (1), the flow rate of the cooling water flowing into the adsorption bed (4) must be high and the outlet temperature of the cooling water must be high to satisfy the condition (2) Use less. Therefore, since the conventional heat exchange method can not satisfy the conditions (1) and (2) simultaneously, it is necessary to determine the cooling water flow rate appropriately between the two conditions.

That is, in order to adjust the two conditions fundamentally, in the present invention, it is a structural problem that only one variable (flow rate of cooling water flowing into the adsorption bed) should be controlled. Therefore, in the present invention, We propose a heat exchange system and method that can meet two conditions simultaneously by introducing a new process design that can be added.

In the embodiment of the present invention, not only the flow rate of the cooling water flowing from the lower end of the adsorption bed 4 but also the structure for controlling the flow rate of the cooling water flowing in the adsorption bed 4 is reflected in the heat exchange system.

That is, the heat exchange system, which is one of the structures of the present invention, utilizes the fact that adsorption occurs mostly under the adsorption bed 4 due to the directional characteristics of the gas and the solid in the adsorption bed 4, The lower end of the adsorption bed 4 is supplied with a sufficient amount of heat so that only a part of the heat-exchanged cooling water flows from the lower end of the adsorption bed 4 to the upper end of the adsorption bed 4, To be maximum. (Adsorption performance, economical optimization at the same time)

As described above, according to the present invention, the cooling water is separated from the adsorption bed 4 and the adsorption performance and economic volume can be realized through the heat exchange system composed of the two heat exchangers 40a and 40b (the first heat exchanger 40a: , The second heat exchanger (40b): the lower end), and the cooling water is not separated and the amount of cooling water used in the middle of the adsorption bed is lower than that of the cooling water used in the middle Of course it is possible.

4 and 10, the heated cooling water used in the high-temperature desorption bed 30, in such a manner as to heat-exchange the heated cooling water used before entering the high-temperature desorption bed 30, The cooling water that has been heat-exchanged in the adsorption bed can not have a temperature corresponding to the operation temperature thermodynamically, so an additional heater system is provided to realize the corresponding operating temperature.

That is, as the second heat exchanger 40b, the cooling water flowing into the lower portion of the lower portion of the adsorption bed 4 and being discharged is separated into two cooling water flows. The third cooling water CWR3 is separated from the cyclone 11 and the bag filter 12 and then heated to the operating temperature by using the first steam heater HE1 and the second cooling water CRW2 which is the other one of the heat is heat exchanged by the internal heat exchange And is discharged without being used.

The flow rate of the fourth cooling water (CRW4), which flows into the upper portion of the lower end of the adsorption bed 4 and then exits again, is heated to the operation temperature by using the second steam heater HE2 as the first heat exchanger 40a ) And the third cooling water (CRW3) of the first heat exchanger (40a) which is heat-exchanged at the same temperature, and is supplied to the high temperature desorption bed (30).

As shown in FIG. 4 and FIG. 10, the cooling water flow rate initially determined is heat exchange in the entire adsorption bed, so that the adsorption performance and the optimization of economy can not be satisfied at the same time. However, In the system, the initially determined cooling water flow rate (CW) is only responsible for heat exchange at the bottom of the adsorption bed, and thereafter the heat exchange from the bottom of the adsorption bed to the top is performed through the controlled cooling water flow rate, i.e., the first cooling water (CWR1) . That is, the amount of the first cooling water (CW) is a parameter for controlling the adsorption performance condition, and the first cooling water (CWR1) is a variable for controlling the cooling water outlet temperature to maximize the heat exchange.

Here, as the first heat exchanger 40a, the flow of the cooling water that flows into the lower portion of the lower end of the adsorption bed 4, is discharged and then separated and flows into the high temperature desorption bed 30 is indicated by the third cooling water CWR3, The remaining flow of the cooling water is indicated by the second cooling water (CWR2). The third cooling water CWR4 and the fourth cooling water CWR4 are combined together as the second cooling water CWR4 as the second cooling water CWR4 as the second cooling water CWR4 flowing into the upper part of the lower end of the adsorption bed 4, And flows into the high-temperature desorbing bed 30 and exits through the fifth cooling water CWR5.

5 is a schematic diagram of a cooling water flow in a new heat exchange system in a temperature and pressure mobile phase adsorption process system according to an embodiment of the present invention. 5, the separated third cooling water CRW3 of the second heat exchanger 40b is heat-exchanged by the waste gas heat exchange system first steam heater HE1, and then the third steam water heater HE3 is connected to the steam The heat exchanged into the high temperature desorption bed 30 and the heated cooling water fourth cooling water CWR4 is heat-exchanged only through the second steam heater HE2 and flows into the high temperature desorption bed 30.

FIG. 6 is a graph showing the temperature gradient for the structure of the heat exchange system of the temperature and pressure mobile phase adsorption process system according to the embodiment of the present invention. As shown in FIG. 6, the blue line shows a temperature change predicted when the heat exchange system proposed in the embodiment of the present invention is used, and the adsorbed bed (ADB) 4, when compared with the existing heat exchange structure (black line) It is possible to predict that the cooling water at a higher temperature can be obtained at the high temperature desorption bed (A-DEB) 30, and thus the steam heating amount required before applying to the high temperature desorption bed (A-DEB) 30 is smaller than that of the conventional heat exchange system structure. The red line indicates the temperature change of the third cooling water (CWR3).

FIG. 7 is a view showing changes in the temperature of the cooling water through the design of the heat exchange system of the temperature and pressure mobile phase variation adsorption process system according to the embodiment of the present invention obtained through the computer simulation simulator and the change in the cooling water temperature in the conventional heat exchange system design. 7, the horizontal axis represents the height of the adsorption bed 4, and the vertical axis represents the temperature of the cooling water heat-exchanged in the adsorption bed 4, including the flow rate of the cooling water to be introduced from the lower portion of the adsorption bed 4 The results were derived after changing only the structure of the heat exchange system while maintaining the remaining conditions constant. Until the length of the adsorption bed 4 is about 50 cm, the two design structures have a similar temperature, but since the cooling water flow rate is controlled in the proposed design of the heat exchange system thereafter, the temperature obtained at the outlet of the adsorption bed 4 It can be seen that the proposed process is about 40 ~ 50 ℃ higher than the conventional process.

8 is a graph showing an adsorption amount curve according to temperature pressure fluctuation. As shown in Fig. 8, H0 represents the temperature and pressure at the outlet of the adsorption bed 4, and in the case of the conventional process, the pressure in the desorbent bed 5 is lowered from P _H to P _L using a low pressure pump, (H0-> H1 in FIG. 5), whereas in the case of adding the high temperature desorbent bed 30 according to the present invention, the heat source is supplied from the high temperature desorbent bed 30 to increase the temperature from T _L to T _H After a certain amount is desorbed, the desorption bed 5 changes the operating condition to a low pressure using a low pressure pump to finally perform desorption. In this case, the low pressure required to obtain the desired recovery rate exists between P _L and P _I , and as a result, the cost of the low-pressure pump can be reduced compared to the conventional process. (H0- > H1 > H2 in Fig. 5)

4, the adsorption bed 4, the high temperature desorbing bed 30 and the desorbing bed 5 are connected to each other through a heat exchanger to minimize the supply heat source by performing heat exchange in the process itself, Optimization is possible.

[Table 1] is a table showing the heat quantity required according to the heat capacity and the exit temperature of each flow in the process.

Specific heat of CO ₂ : N ₂ = 0.13: 0.87: 1.0299 J / gK, 26 캜 Exhaust gas (CO ₂ : N ₂ = 0.13: 0.87 Mass flow of the exhaust gas: 167.79 ton / hr (120 ° C, 101.3 kPa, CO ₂ : N ₂ = 0.13: 0.87), mass flow of the adsorbent: 360 ton / hr)

H1 corresponds to the adsorbent flowing into the adsorption bed 4 from the desorbent bed 5, H2 is the exhaust gas flowing into the adsorption bed 4, and C1 is the adsorbent from the adsorption bed 4 to the high- Respectively. When the heat exchange is not performed, the total heat amount required for cooling and heating corresponds to 85,282,000 kJ / hr. As shown in FIG. 5, the heat amount required for cooling or heating each flow can be effectively exchanged through the heat exchanger 20 .

Heat required for cooling / heating the process during heat exchange is shown in Fig. Fig. 9 shows the case where the temperature required for cooling water at 11 占 폚 is 100 占 폚, and the maximum temperature of the cooling water is assumed to be 100 占 폚, which is the evaporation temperature. It can be seen numerically that the heat required for cooling or heating at the final stage is 62,098,000 kJ / hr, which is lower than the case of 85,282,000 kJ / hr without heat exchange, considering the amount of heat required for cooling water at 100 ° C.

If there is difficulty in solid-to-solid heat exchange but the heat exchange between the adsorbents is effective, the heat required for cooling / heating is calculated to be 26,077,000 kJ / hr and, as shown in FIG. 4, In order to minimize the cooling water flow, heat exchange as shown in FIG. 4 is also possible. In this case, heating or cooling is performed only at the required local points, and the cooling water circulates in the other points so that necessary heat can be supplied or removed.

4 and 10, the temperature of the adsorption bed 4, the high temperature desorbing bed 30 and the desorbing bed 5 is controlled by the heat exchanging method. In the adsorbing bed 4, Temperature desorbent bed 30 and the desorbent bed which are located at the lower part through the reflux pipe 7 and the adsorbent is introduced into the high temperature desorbent bed 30 by the adsorbent transfer device 6. [

Unlike the desorbing bed 5, the high-temperature desorbing bed 30 is a device for desorbing a first adsorbent by applying heat to the adsorbent rather than desorbing through temperature and pressure. _A ), and the temperature is at least above the desorbing bed temperature (T _D ). After the strong adsorbent such as CO _{2 is} primarily desorbed from the high temperature desorbent bed 30, the adsorbent is again transferred to the desorbent bed 5 located below the high temperature desorbent bed 30 through the reflux tube 7 .

Since the pressure of the desorbing bed 5 is high in the high temperature desorbing bed 30, it is possible to induce the natural movement according to the pressure difference, so that the position of the high temperature desorbing bed 30 can be adjusted, (5) and the height difference can be adjusted. That is, even if the high-temperature desorbing bed 30 is at a low position of the desorbing bed 5, it is possible to overcome the force due to the gravity due to the difference in height and to selectively move the adsorbent through the reflux tube 7 The position of the desorbent bed 5 can be determined.

The desorbent bed 5 maintains a relatively low pressure P _D and a high temperature T _D as compared with the adsorbent bed 4 so that a substantial amount of strong adsorbent material such as CO _{2 in the} adsorbent is desorbed. After the dust is removed through the cyclone 14 and the bag filter 15, the desorbed gas is discharged through the gas pump 13, and the desorbed powder is returned to the adsorption bed 4 through the adsorbent conveying device Goes.

Since the adsorbent conveying device 6 is relatively positioned higher than the desorbing bed, it is possible to convey the adsorbent powder using a device such as a bucket elevator. However, since the pressure of the adsorbing bed 4 is higher, The injection unit into which the adsorbent flows from the desorbent bed 5 is preferably a double-headed (6A) structure.

11 is a view showing an example of the structure of an injection unit of an adsorption bed in which an adsorbent is transferred from a desorption bed in the adsorption process system according to the present invention. As shown in Fig. 11, the injection unit has a structure of two doors. After the double door 1 is opened and the adsorbent is injected, the double door 1 is closed again, and then it is raised to a pressure equal to the pressure of the adsorption bed by an external compressor or the like. When the pressure becomes the same, the double door 2 is opened to inject the adsorbent into the adsorption bed 4. With this double-door structure, it is possible to transfer the adsorbent from the low-pressure desorbent bed 5 to the adsorbent bed 4, which is atmospheric pressure or high pressure, and then feed the adsorbent.

FIG. 12 is a flow chart of the gas mixture and the adsorbent in the mobile phase temperature pressure swing adsorption process during the operation of the adsorption / desorption process system using the stepwise desorption shown in FIGS. 4 and 11. FIG. 8, the gas mixture is continuously supplied to the adsorption bed (atmospheric pressure or high pressure, low temperature) (4) through the blower 10 or the compressor 10 '(S100) The mixture is selectively adsorbed to the adsorbent and the concentrated weakly adsorbed gas is recovered (S110) and the adsorbent flowing from the lower part of the adsorption bed 4 is moved through the reflux pipe 7 to the lower temperature desorption bed 30 (S120)

The adsorbent introduced from the adsorbent bed is first desorbed at a high temperature from the high temperature desorbent bed 30 (at atmospheric pressure or high pressure and high temperature) at a high temperature (S130), and the adsorbent of the high temperature desorbent bed 30 is desorbed from the desorbent bed , High temperature) 5 through the reflux tube 7 (S140), the adsorbed gas is separated from the desorbed bed (low pressure, high temperature) 5 to regenerate the adsorbent, and the concentrated strong adsorbent gas CO2, etc.) is recovered (S150), and the regenerated adsorbent is transferred to the adsorption bed 4 through the adsorbent conveyance device 6 and circulated. (S160)

The basic operation of the adsorption process system shown in FIG. 11 is very similar to the case of the normal pressure adsorption-vacuum desorption of FIG. 4, but when the gas mixture is injected into the desorption bed, the adsorption process system is operated at a high pressure through a compressor 10 ' Supply is different. The difference is that the kinetic energy of the concentrated weakly adsorbate is recovered through the expander 16 and the generator 17.

As described above, in the mobile phase temperature and pressure swing process system for gas separation using the stepwise desorption of the present invention, when the adsorption bed 4 is located at the upper portion and the adsorbent is moved from the upper portion to the lower portion when the desorption bed 5 is located at the lower portion The exhaust gas is moved from the high-pressure adsorbent bed 4 to the relatively low-temperature high-temperature desorbent bed 30 and the desorbent bed 5, so that the reduction of the recovery rate due to the contamination of the exhaust gas of the exhaust gas can be reduced, · Since there is no height restriction between desorbing beds, it is possible to realize a small scale device, and the valve operation can be simplified.

When the high-temperature desorbing bed 30 is added between the adsorbing and desorbing beds, a large amount of desorbing is performed in the high-temperature desorbing bed 30, so that the operation cost of the low-pressure pump of the desorbing bed 5 can be reduced have.

Hereinafter, the effects of the process conditions of the process system illustrated in FIGS. 4 and 11 will be described.

pressure

Depending on the characteristics of the target gas mixture and the target adsorbent, the operating conditions of the process can be divided into atmospheric adsorption-vacuum desorption operation, high pressure adsorption-atmospheric desorption operation, high pressure adsorption-vacuum desorption, and the like. In order to overcome the disadvantage that the operation of the atmospheric pressure adsorption-vacuum desorption operation is performed in the system composed of only the adsorption bed and the desorption bed but the operation cost of the low pressure pump for the vacuum is high, in the embodiment of the present invention, In addition, the high-pressure adsorption-low pressure desorption operation can be performed by using the stepwise desorption to further reduce the pump operation cost.

The gas mixture 1 at normal pressure is supplied to the adsorption bed 4 so that the adsorption bed 4 is operated at the normal pressure P _A and the strong adsorbate is desorbed first from the high temperature desorption bed 30, The desorbing bed 5 for recovery is operated at a low pressure (P _D <P _A ). The concentrated adsorbent from the desorbent bed (5) is withdrawn using a gas pump.

10, in the case of the high-pressure adsorption-atmospheric pressure desorption operation, the high-pressure gas mixture 1 is supplied to the adsorption bed 4 so that the adsorption bed is operated at the high pressure P _A , The bed 5 is operated at atmospheric pressure (P _D <P _A ). The weak adsorbate enriched gas from the adsorption bed 4 is withdrawn through the diffuser 16 and the generator 17, The mechanical energy generated by the pressure difference is also collected.

Temperature

The heat of adsorption generated during the adsorption is recovered through a heat exchanger of the adsorption bed (4) and supplied to the desorption bed to be used as thermal energy required for desorption. When the raw gas mixture 1 is at a high temperature, the temperature of the gas mixture is lowered to the temperature of the adsorbent bed (T _A ) through a heat exchanger before the raw material feed to recover heat energy from the raw material. The recovered heat energy is recovered through the heat exchanger 30 and the desorbing bed 5 so as to maintain the desorption temperature T _D.

As the temperature is lower, the gas adsorbs well to the adsorbent. When the gas mixture is adsorbed to the adsorbent in the adsorbent bed 4, adsorption heat is generated and the temperature of the bed rises. Therefore, the temperature of the adsorbent bed 4 is increased through the cooler, Thereby lowering the temperature.

The higher the temperature is, the better the gas is desorbed from the adsorbent. The temperature of the adsorbent bed 4 is increased through the heater 8 because the temperature of the bed drops due to desorption when the gas is desorbed from the adsorbent .

Powder  transfer

The adsorbent regenerated in the desorbing bed (5) is conveyed to the adsorption bed (4) through the conveying device. At this time, the powder conveying device 6 uses a bucket elevator or a bucket conveyor. Then, the adsorbent is moved from the adsorbent bed located at a relatively high position to the high-temperature desorbent bed 30 through the reflux tube 7, and again the adsorbent is moved from the high-temperature desorbent bed 30 to the desorbent bed through the reflux tube 7 , Since the high-temperature desorbing bed 30 has a pressure higher than that of the desorbing bed 5, it is possible to induce a natural movement by the pressure difference.

As described above, the ordinary exhaust gas used in the adsorption process system according to the present invention is composed of 10% of carbon dioxide (CO ₂ ) and 90% of nitrogen (N ₂ ), and in the case of carbon dioxide (CO ₂ ) It is not possible to collect all of the components in the one-step process. Therefore, the PSA process is operated in at least two or more steps to separate and recover the carbon dioxide. The first stage of the PSA process accounts for a significant portion of the overall operating cost, and the mobile phase temperature pressure swing adsorption process of the present invention can replace this first stage PSA process and the stepwise desorption Stage purity of the two-stage separation process when the purity is increased by injecting the carbon dioxide produced through the one-stage mobile phase temperature-pressure swing adsorption process into the two-stage separation process, Thereby reducing the overall operation cost.

In addition, the system of the present invention performs heat exchange using cooling water and steam in the utility to maintain the temperature change occurring in the adsorption column and the desorption column at the operating optimum point temperature in a mobile phase temperature pressure swing adsorption process that enables continuous processing do. The system according to the present invention, which can minimize this cost, is significant from an industrial point of view because the utility cost takes a large cost in the overall operation cost.

While the invention has been shown and described with respect to the specific embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims. Anyone with it will know easily.

4: adsorption bed, 5: desorption bed, 6: adsorbent conveying device, 6A: double door
7: adsorbent reflux tube, 9: heater,
10: blower or compressor, 11,14: cyclone,
12, 15: bag filter, 16: expander, 17: generator
30: high temperature desorption bed, 35: cooler, 40a: first heat exchanger, 40b: second heat exchanger

Claims (12)

An adsorption bed for selectively adsorbing the introduced mixed gas;
A blower installed at a lower portion of the adsorption bed to inject the mixed gas;
A high temperature desorbing bed disposed below the adsorbing bed to desorb the adsorbent primarily by heating the adsorbent conveyed through the lower part of the adsorbing bed;
A desorbent bed desorbed from the high-temperature desorbent bed to desorb the adsorbent powder which is desorbed from the desorbent bed, the desorbent bed being located below the high-temperature desorbent bed; And
A transfer device for transferring the adsorbent powder desorbed from the desorbent bed to the adsorbent bed; And
The cooling water is introduced into the lower portion of the lower portion of the adsorption bed to remove heat, the cooling water to be discharged is separated, the separated cooling water is again introduced into the lower portion of the lower portion of the adsorption bed to remove heat, And a heat exchange system for heating and introducing the high temperature desorption bed into the high temperature desorption bed to increase the temperature of the high temperature desorption bed,
Wherein the high temperature desorbent bed is the same as the pressure P _A of the adsorbent bed and the desorbent bed is maintained at a lower pressure P _D and a higher temperature T _D than the adsorbent bed. Mobile phase temperature pressure swing adsorption process system.
The method according to claim 1,
The heat exchange system includes:
The first cooling water is separated from the lower part of the adsorption bed to remove the cooling water from the lower part of the adsorption bed, and the fourth cooling water is heated to be introduced into the high temperature desorption bed The temperature of the desorption bed is increased by raising the temperature of the desorption bed and discharging the second cooling water partially separated from the cooling water discharged from the lower part of the absorption bed, And a second heat exchanger, wherein the mobile phase temperature and pressure swing adsorption process system for gas separation.
3. The method of claim 2,
Wherein the third cooling water and the fourth cooling water, which are discharged from the adsorption bed and flow into the high temperature desorption bed, are heated by at least one steam heater installed in each flow path. .
The method of claim 3,
Wherein the steam heater for heating the third cooling water includes a steam heater using waste gas discharged from the upper end of the adsorption bed.
5. The method of claim 4,
Wherein the injection unit through which the adsorbent is introduced from the desorbent bed has a double-layered structure.
6. The method according to any one of claims 1 to 5,
The adsorbing bed comprises:
Characterized in that the inner space of the adsorption bed occupied by the adsorbent is divided into an upper end and a lower end and an area of a vertical cross section of the lower end is smaller than the upper end area and the mixed gas is injected into an upper end of the adsorption bed Mobile phase temperature pressure swing adsorption process system for separation.
An adsorption bed for selectively adsorbing the introduced mixed gas;
A compressor installed under the adsorption bed for compressing and injecting the mixed gas;
A high temperature desorbing bed disposed below the adsorbing bed to desorb the adsorbent primarily by heating the adsorbent conveyed through the lower part of the adsorbing bed;
A desorbent bed desorbed from the high-temperature desorbent bed to desorb the adsorbent powder which is desorbed from the desorbent bed, the desorbent bed being located below the high-temperature desorbent bed;
A transfer device for transferring the adsorbent powder desorbed from the desorbent bed to the adsorbent bed;
The cooling water is introduced into the lower portion of the lower portion of the adsorption bed to remove heat, the cooling water to be discharged is separated, the separated cooling water is again introduced into the lower portion of the lower portion of the adsorption bed to remove heat, And a heat exchange system for heating and introducing the high temperature desorption bed into the high temperature desorption bed to increase the temperature of the high temperature desorption bed,
Wherein the high temperature desorbent bed is the same as the pressure P _A of the adsorbent bed and the desorbent bed is maintained at a lower pressure P _D and a higher temperature T _D than the adsorbent bed. Mobile phase temperature pressure swing adsorption process system.
8. The method of claim 7,
The heat exchange system includes:
The first cooling water is separated from the lower part of the adsorption bed to remove the cooling water from the lower part of the adsorption bed, and the fourth cooling water is heated to be introduced into the high temperature desorption bed The temperature of the desorption bed is increased by raising the temperature of the desorption bed and discharging the second cooling water partially separated from the cooling water discharged from the lower part of the absorption bed, And a second heat exchanger, wherein the mobile phase temperature and pressure swing adsorption process system for gas separation.
9. The method of claim 8,
Wherein the third cooling water and the fourth cooling water, which are discharged from the adsorption bed and flow into the high temperature desorption bed, are heated by at least one steam heater installed in each flow path. .
10. The method of claim 9,
Wherein the steam heater for heating the third cooling water includes a steam heater using waste gas discharged from the upper end of the adsorption bed.
11. The method according to any one of claims 7 to 10,
Wherein the injection unit through which the adsorbent is introduced from the desorbent bed has a double-layered structure.
12. The method of claim 11,
The adsorbing bed comprises:
Wherein an inner space of the adsorption bed occupied by the adsorbent is divided into an upper portion and a lower portion and an area of a vertical cross section of the lower end is smaller than an upper end area,
And the mixed gas is injected into the upper end of the adsorption bed.

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