KR101442673B1 - Temperature and pressure swing moving bed adsorption system integrated with new heat exchanger - Google Patents

Abstract

The present invention relates to an adsorption process system for selective gas separation using a stepwise desorption and using a new heat exchange system, 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 transfer device for transferring the adsorbent flowing from the lower part of the adsorption bed; A high temperature desorbing bed disposed above the adsorbing bed to desorb the adsorbent primarily by heating the adsorbent conveyed and introduced from the conveying device; A desorbent bed for desorbing the adsorbent in a second stage by moving the desorbent powder desorbed from the high temperature desorbent bed; A reflux tube for moving 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 a high temperature (T _D ) relative to the size of the adsorbent particles, and by controlling at least one of the size of the adsorbent particles, the diameter and the length of the reflux tube, The backflow of the gas is prevented.
According to the present invention as described above, it is possible to operate at an efficient fixed condition and to be able to continuously operate, so that it is possible to obtain higher productivity as compared with other gas separation apparatuses of the same scale, It is possible to reduce the energy required for each stage by using a new heat exchange system and to operate at a low cost, so that it is possible to operate efficiently, and the adsorption performance and economy can be improved. It can also be applied to the separation of various types of gas mixtures.

Description

TECHNICAL FIELD [0001] The present invention relates to a temperature-pressure fluctuation adsorption process system using a new heat exchange system,

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 performing pressurization, high pressure adsorption, depressurization discharge, depressurization or modification operation in one adsorption bed 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 bed is heated at a temperature (T _L , q _ads ) under 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 exchange system.

The activated carbon flowing down from the adsorption section is in contact with the desorbed gas in the lower part of the tube which is heated in the heat exchange system. 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, firstly, the adsorption process is a continuous process, the gas pumps can be operated continuously under fixed conditions, and each pump can be operated under the operating conditions of maximum efficiency, (2) to make it possible to obtain higher productivity in the same scale of apparatus, (3) to be able to perform pressure fluctuation and temperature fluctuation operation under desired conditions, and (4) It is aimed to increase operating efficiency of system and pump, to reduce operating cost, to increase the efficiency of separation and recovery of mixed gas. Fifth, by using heat exchange system, it is possible to reduce energy consumption and low cost operation at each stage, 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 adsorbed mixed gas, A blower installed at a lower portion of the adsorption bed to inject the mixed gas; A transfer device for transferring the adsorbent flowing from the lower part of the adsorption bed; A high temperature desorbing bed disposed above the adsorbing bed to desorb the adsorbent primarily by heating the adsorbent conveyed and introduced from the conveying device; A desorbent bed for desorbing the adsorbent in a second stage by moving the desorbent powder desorbed from the high temperature desorbent bed; A reflux tube for moving 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 a high temperature (T _D ) relative to the size of the adsorbent particles, and by controlling at least one of the size of the adsorbent particles, the diameter and the length of the reflux tube, The back flow of the gas is prevented.

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.

According to a second aspect of the present invention, there is provided a compressor comprising: a compressor installed at a lower portion of the adsorption bed for compressing and injecting the mixed gas; A transfer device for transferring the adsorbent flowing from the lower part of the adsorption bed; A high temperature desorbing bed disposed above the adsorbing bed for desorbing the adsorbent primarily by heating the adsorbent conveyed and introduced from the conveying device; A desorbent bed disposed above the adsorbent bed to desorb the adsorbent in a second order by moving the adsorbent powder desorbed from the high temperature desorbent bed; A reflux tube for moving 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 a high temperature (T _D ) relative to the size of the adsorbent particles, and by controlling at least one of the size of the adsorbent particles, the diameter and the length of the reflux tube, The back flow of the gas is prevented.

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.

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. In addition, 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 scale, pressure fluctuation and temperature fluctuation operation can be performed under desired conditions, It is possible to reduce the energy required for each stage and to operate at a low cost, thereby enabling efficient operation and achieving energy saving, thereby improving the adsorption performance and economical efficiency.

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 a temperature and pressure mobile phase varying adsorption process system according to an embodiment of the present invention,
FIG. 5 is a schematic view 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,
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 a temperature and pressure mobile phase variable adsorption process system according to another embodiment of the present invention,
11 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 10. Fig.

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

FIGS. 4 and 10 are views illustrating a configuration of a temperature and pressure mobile phase 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 at a low pressure 10 exemplifies a process system in which adsorption proceeds at high pressure and desorption proceeds at normal pressure. In the case of a heat exchange system, there is provided a heat exchange system in the same manner as in FIGS. 4 and 10, but the cooling water circulates inside and only the required heat is supplied from outside to minimize the flow rate of cooling water. 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 temperature and pressure mobile phase adsorption process system according to the embodiment of the present invention includes 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 transfer device 6 for transferring the adsorbent flowing from the lower part of the adsorption bed 4; A high temperature desorbing bed (30) located above the adsorbing bed to primarily desorb the adsorbed material by heating the adsorbent conveyed and flowing in the conveying device (6); A desorbent bed (5) for desorbing the adsorbent material by desorbing the adsorbent powder desorbed from the high temperature desorbent bed (30); A reflux tube (7) for moving the adsorbent powder desorbed from the desorbent bed (5) to the adsorbent bed (4); And the cooling water is introduced into the lower part of the lower part of the adsorption bed to separate the cooling water out of the lower part of the absorption bed, And a heat exchange system (40a, 40b) for heating the cooling water to be discharged and flowing 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) a pressure of 4 (P _a) and the same, and the desorption bed 5 is kept the lower pressure (P _D) and a temperature (T _D) as compared to the adsorbent bed (4), and of the adsorbent particle size , The backflow of some gas generated by the pressure difference in the reflux pipe (7) is prevented by controlling at least one of the diameter and the length of the reflux pipe (7).

Here, when the flow rate of the gas mixture is large as in the exhaust gas of the factory, it is extremely difficult to pressurize and pressurize all of the gas mixture into the adsorption bed 4, so that the gas mixture is supplied from the blower 10 through the blower 10 at normal pressure The gas mixture is injected into the adsorption bed and is firstly recovered in the high temperature desorption bed 30 of the same pressure to select the operation method of recovering the strong adsorbed gas from the desorption bed 5 which is relatively low in pressure with the adsorption bed 4 Should be.

If the flow rate of the gas mixture to be treated is not large, the gas mixture may be supplied to the compressor 10 ', such as the process by the process system illustrated in FIG. 4, By pressurizing and injecting into the adsorption bed, the process can be configured at 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 transferred to the high temperature desorption bed 30 by using the closed powder transfer device 6 and is injected.

The high temperature desorbent bed 30 is a device for desorbing the adsorbent by applying heat to the adsorbent bed 4 and is located between the adsorbent bed 4 and the desorbent bed 5 to reduce the cost of maintaining the desorbent bed 5 at a vacuum or a low pressure And is a device for stepwise detachment. 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 desorption bed 30 can be obtained through the heat exchange system 40 in the process itself, and it is possible to provide an efficient system for additionally supplying the required heat source.

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 portion), a method of using a cooling water flow rate regulator in the middle and a flow rate smaller than the cooling water flow rate used in the lower half of the adsorption bed Of course it is possible.

4 and 10, the heated cooling water used in the high-temperature desorption bed in the manner of exchanging the heated cooling water used before entering the high-temperature desorption bed 30, The cooling water heat exchanged in the adsorption bed can not have a temperature corresponding to the operation temperature thermodynamically, so that an additional heater system is provided to realize the corresponding operation 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 second heat exchanger, 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 second heat exchanger 40b, the flow of the cooling water that flows into the lower portion of the lower end of the adsorption bed 4, is discharged after being discharged, and separated 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 first cooling water CWR4 and the fourth cooling water CWR4 are combined as the first cooling water CWR4 as the first cooling water CWR4 as the first 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 is heat-exchanged by the waste gas heat exchange system first steam heater HE1, and then heat-exchanged with steam through the third steam heater HE3 The heated cooling water fourth cooling water (CWR4) enters the high temperature desorption bed through heat exchange only through the second steam heater (HE2) and flows into the high temperature desorption bed.

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)

Further, as shown in FIG. 4, the adsorption bed, the high-temperature desorption bed 30, and the desorption bed are connected through the newly proposed heat exchange system, thereby minimizing the supply heat source by performing heat exchange in the process itself. Do.

[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 a difficulty in the heat exchange between solids, 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, the required cooling water flow rate The heat exchange as shown in Fig. 4 is also possible in order to minimize, in which case heating or cooling is performed only at the required local point, and the cooling water can circulate inside the other points to supply or remove the necessary heat.

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 system as described above. 6) or a transfer pipe, and the adsorbent is heated by the steam heater of the heat exchange system and flows into the high temperature desorption bed (30).

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 through the reflux tube 7.

Since the pressure of the high temperature desorbing bed 30 is higher than the pressure of the desorbing bed, 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, And the height difference can be adjusted. That is, it is possible to overcome the force due to the gravity due to the difference in height and to selectively position the desorbing bed 5 so that the adsorbent can be moved through the reflux pipe 7 by a pressure difference.

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 adsorbed by gravity along the adsorbent reflux tube 7 And returns to the bed (4).

11 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 10. 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 adsorbed on the selected gas is transferred to the high temperature desorbent bed 30 through the transfer device 6 (S120) The adsorbent of the high temperature desorbent bed 30 is moved to the desorbent bed (low pressure, high temperature) 5 by the pressure difference (step S130) The adsorbent is recovered by separating the adsorbed gas from the desorbent bed (low pressure, high temperature) 5 to recover the adsorbent and the concentrated adsorbent (CO ₂ etc.) is recovered (S 150) And is then circulated through the adsorbent reflux tube 7 to the adsorption bed 4 (S160)

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

On the other hand, since the pressure of the adsorption bed 4 is higher than the pressure of the desorbing bed 5 in the process by the mobile phase temperature pressure swing adsorption process system according to the present invention as shown in FIG. 4 and FIG. 10, Accordingly, some gas mixture may leak back to the desorption bed from the adsorption bed. This phenomenon of leaking is caused by a pressure difference between the adsorption bed 4 and the desorption bed 5, and the flow rate thereof is proportional to the pressure difference between the adsorption bed 4 and the desorption bed 5.

By regulating at least one of the size of the adsorbent particles and the diameter and the length of the reflux tube 7, it is possible to prevent the backflow of some gas generated by the pressure difference in the reflux tube 7, It is possible to regulate the pressure drop through the pipe (7), thereby reducing the leakage flow to the extent that it is not a problem.

At this time, the particle size is about 0.1 mm to 10 mm. In addition, the flue gas is usually discharged at about 160 DEG C, and the temperature required for efficient desorption at the desorption bed 5 is about 50 to 70 DEG C. [ Therefore, the energy required for maintaining the temperature of the desorbent bed 5 can be saved by heating the desorbent bed 5 using the flue gas before injecting the flue gas into the adsorbent bed 4.

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

9, 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 adsorbent bed 4 is recovered through the diffuser 13 and the generator 16, And the mechanical energy generated is also collected.

Temperature

The heat of adsorption generated during the adsorption is recovered through the heat exchange system 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 adsorption bed (T _A ) through the heat exchange system before the raw material is supplied to recover the heat energy from the raw material. The recovered heat energy is recovered through the heat exchange system 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 desorbent bed (5) is conveyed to the adsorbent bed (4) by gravity along the adsorbent reflux tube (7). The adsorbent that has flowed to the lower part of the adsorption bed 4 is transferred to and injected into the high temperature desorption bed 30 by using a closed powder conveying device 6. The powder conveying device 6 is a bucket elevator Use a bucket conveyor. The adsorbent of the high temperature desorbent bed 30 is again moved through the desorbent bed through the reflux tube 7. Since the high temperature desorbent bed 30 has the same pressure as the adsorbent bed, It can induce natural movement by car.

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 Process, it is possible to separate into higher purity. As a result, when the purity is increased by injecting the carbon dioxide produced through the one-stage mobile phase temperature swing adsorption process into the two-stage separation process, the burden on the purity of the two- 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 changes occurring in the adsorbent bed and the desorbent bed 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, 7: adsorbent reflux tube
8a, 8b: a cooler, 9: a heater, 10: a blower, 10 ': a compressor,
Cyclone, 12,15 bag filter, 16: expander, 17: generator, 30: high temperature desorption bed,

Claims (8)

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 transfer device for transferring the adsorbent flowing from the lower part of the adsorption bed;
A high temperature desorbing bed disposed above the adsorbing bed for desorbing the adsorbent primarily by heating the adsorbent conveyed and introduced from the conveying device;
A desorbent bed for desorbing the adsorbent in a second stage by moving the desorbent powder desorbed from the high temperature desorbent bed;
A reflux tube for moving 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 maintains a lower pressure P _D and a higher temperature T _D than the adsorbent bed, Wherein at least one of the diameter and the length of the reflux tube is controlled to prevent backflow of some of the gas generated by the pressure difference in the reflux tube.
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 And the second cooling water partially separated from the cooling water discharged from the lower part of the lower part of the adsorption bed is discharged and the remaining third cooling water is heated and then introduced into the high temperature desorption bed to increase the desorption bed temperature And a second heat exchanger.
3. The method of claim 2,
Wherein the third cooling water and the fourth cooling water that 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.
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 transfer device for transferring the adsorbent flowing from the lower part of the adsorption bed;
A high temperature desorbing bed disposed above the adsorbing bed to desorb the adsorbent primarily by heating the adsorbent conveyed and introduced from the conveying device;
A desorbent bed disposed above the adsorbent bed to desorb the adsorbent in a second order by moving the adsorbent powder desorbed from the high temperature desorbent bed;
A reflux tube for moving 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 maintains a lower pressure P _D and a higher temperature T _D than the adsorbent bed, Wherein at least one of the diameter and the length of the reflux tube is controlled to prevent backflow of some of the gas generated by the pressure difference in the reflux tube.
6. The method of claim 5,
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 And the second cooling water partially separated from the cooling water discharged from the lower part of the lower part of the adsorption bed is discharged and the remaining third cooling water is heated and then introduced into the high temperature desorption bed to increase the desorption bed temperature And a second heat exchanger.
The method according to claim 6,
Wherein the third cooling water and the fourth cooling water that 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.
8. The method of claim 7,
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.

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