KR20160009895A - Apparatus and method for recovery of retentate - Google Patents

Abstract

In regard to a process of increasing the concentration of a target gas contained in recovery gas when the number of gas separation membrane modules is minimized and also recovering the recovery gas via concentration processes, the present invention relates to gas recovery apparatus and method capable of keeping the concentration of a target gas contained in recovery gas at a constant level. The gas recovery apparatus according to the present invention comprises a bidirectional target gas recovery apparatus and (n+1) gas storage tanks. The bidirectional target gas recovery apparatus comprises a first gas separation membrane module and a second gas separation membrane module, performs an n times concentration processes (n is a natural number), and separates feed gas into concentration process recovery gas and concentration process penetration gas via each concentration process. During an n^th concentration process, the gas stored in an n^th gas storage tank is supplied to a gas separation membrane module and separated into an n^th concentration process penetration gas and an n^th concentration process recovery gas. In addition, the n^th concentration process penetration gas is stored in an (n-1)^th gas storage tank, and the n^th concentration process recovery gas is stored in an (n+1)^th gas storage tank. A (2n-1)^th concentration process is performed in a forward direction, and a 2n^th concentration process is performed in a backward direction. In addition, the forward direction is the gas flow from a first stage to a second stage in the first gas separation membrane module, and the backward direction is the opposite direction to the forward direction.

Description

[0001] APPARATUS AND METHOD FOR RECOVERY OF RETENTATE [0002]

The present invention relates to a gas recovery apparatus and method, and more particularly, to an apparatus and method for recovering a recovered gas by increasing the target gas concentration in the recovered gas while minimizing the number of gas separation membrane modules, To a gas recovery apparatus and method capable of keeping the concentration of the target gas contained in the gas recovery apparatus constant.

SF ₆ is a typical electrical insulating material for electric power equipment and is used in the cleaning process of semiconductor wafers and LCD panels. Such SF ₆ has been the impact on global warming is known to be higher than carbon dioxide, more than 23,900 times, global warming is one of the largest six materials cited in the UNFCCC Parties Conference held in Kyoto in 1997 bar . Therefore, a process for SF ₆ is urgently required.

The processing method for the SF _6, there is a first method to decompose SF _6. Since SF ₆ is very stable, it requires a high energy such as plasma to decompose and has the disadvantage that by-products having high toxicity and corrosivity such as S ₂ F ₁₀ , SF ₄ , and HF are produced during the decomposition process. If such problems with the decomposition considering the continuous price rise of SF ₆ by effectively recovering SF ₆ is highly desirable in terms of reducing production costs to promote reuse.

Techniques for recovering SF ₆ is a technology for recovering only the SF ₆ in a mixed containing the SF ₆ gas, naengbeop seam in detail, there is a method such as a PSA (pressure swing adsorption) method, membrane separation process, the two of the gas separation membrane module Many studies have been conducted on the membrane separation method used. The membrane separation method is advantageous in that the structure of the apparatus is relatively simple and the recovery rate is comparatively excellent. An example of the membrane separation method is disclosed in Korean Patent No. 10-1249261.

In the membrane separation method, the waste gas is injected into the separation membrane module, and the separation membrane module proceeds by separating the injected waste gas into SF ₆ (recovery gas) and other gases (permeation gas). The treatment characteristics of the membrane separation method are determined by the selectivity and permeability of the membrane module. A high permeability of the membrane module is advantageous in that the treatment capacity is large. However, since the membrane having high permeability is low in selectivity, have.

As described above, the selectivity and the transparency of the separation membrane module have a trade-off. In the conventional case, a plurality of separation membrane modules are formed in a multi-stage configuration to enable a separation performance and a processing capacity of a certain level. However, when the plurality of separation membrane modules are repeatedly constructed in a multi-stage form, there is a disadvantage that the device configuration becomes complicated.

Korean Patent No. 10-1249261

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to provide a gas separation membrane module in which the target gas concentration in the recovery gas is increased while minimizing the number of gas separation membrane modules, And it is an object of the present invention to provide a gas recovery apparatus and method capable of keeping the concentration of a target gas contained therein constant.

In order to achieve the above object, a gas recovery apparatus according to the present invention comprises a first gas separation membrane module and a second gas separation membrane module, wherein the process of n enrichment processes (n is a natural number) is performed, (N + 1) gas storage tanks for separating the injected gas into a concentrated process gas and a concentrated process permeable gas, and the n-th concentration process is performed by the gas stored in the n-th gas storage tank Is supplied to the gas separation membrane module and is separated into an n-th concentrated process permeated gas and an n-th concentrated process recovery gas, the n-th concentrated process permeated gas is stored in an (n-1) gas storage tank, (2n-1) enrichment process proceeds in the forward direction, the 2n enrichment process proceeds in the reverse direction, and the forward direction is stored in the first stage of the first gasket membrane module In the second stage direction, And the reverse direction is a direction opposite to the forward direction.

The nth recovery gas and the (n + 2) th transparent gas are stored in the (n + 1) -th gas storage tank. The first gas storage tank is further provided with a waste gas supply unit for supplying waste gas containing a target gas to the first gas storage tank. The waste gas supplied from the waste gas supply unit and the second concentrated process transparent gas are stored in the first gas storage tank, The first concentration process permeate gas is discharged to the outside.

The operation time T ₁ of the first concentration step satisfies the following expression 1 and the operation time T _n of the nth concentration step (n is a natural number of 2 or more) satisfies the following expression (2).

(Equation 1)

(Where T ₁ is the operating time of the first concentration step, C ₁ is the capacity of the first gas storage tank, P _{1, max} is the maximum gas pressure in the first gas storage tank, P ₀ is the pressure of the inlet gas supplied to the gas separation membrane module ₁ is the flow rate of the injected gas in the first concentration step, and f ₀ is the flow rate of the used gas in the first concentration step)

(Equation 2)

(T _n (n is a natural number of 2 or more) is the n-th operation period, C _n is the first capacity of the gas storage tank of the concentration step, P _{n, max} is the first maximum gas pressure in the gas storage tank, P ₀ is a gas separation membrane The supply pressure of the injection gas supplied to the module, f _{F, n} is the flow rate of the injection gas in the n th concentration process)

Wherein the bidirectional target gas recovery device includes a forward gas supply device for mixing a supply gas supplied from a gas storage tank of the plurality of gas storage tanks and a second recovery gas supplied from the second gas separation membrane module, A reverse gas mixing unit for mixing a supply gas supplied from one of the gas storage tanks of the plurality of gas storage tanks and a second recovery gas supplied from the second gas separation membrane module in the reverse direction of the concentration process, A first gas separation membrane module for separating an injection gas supplied in a forward or reverse direction into a first permeation gas and a first recovery gas in accordance with a first SC value (? ₁ ) set; and a second gas separation membrane module And a second gas separation membrane module for separating the gas into a second permeable gas and a second recovered gas in accordance with a second SC value (? ₂ ) The second SC value [theta] ₂ is set so that the target gas concentration of the supply gas is equal to the target gas concentration of the supply gas.

Wherein the second SC value (? ₂ ) is calculated by the following Equation (1) or (2).

(Equation 1)

(? ₂ is the second SC value, X _F is the target gas concentration in the feed gas,? ₁ is the selectivity of the first gas separation membrane module, and? ₂ is the selectivity of the second gas separation membrane module)

(Equation 2)

(θ ₂ is a second SC value, X _F is a target gas concentration in the feed gas, and α ₁ is a selectivity of the first gas separation membrane module and the second gas separation membrane module)

The first SC value (? ₁ ) is calculated by the following equation.

(expression)

(θ ₁ is selected in the first SC value, e ₁ is a first gas separation membrane module, the target gas concentration, α ₁ is a first gas separation membrane modules in the target concentration in Fig, X _F is the feed gas that is applied to a first gas separation membrane module Degree)

A forward gas pressure control device for controlling the gas of the forward gas mixing part to a predetermined pressure and supplying the gas to the first gas separation membrane module; and a controller for controlling the gas of the reverse gas mixing part to a predetermined pressure and supplying it to the first gas separation membrane module A supply pressure control device may further be provided.

In addition, the first first permeate gas flow rate and the number of times the gas flow rate of the first gas separation membrane module by controlling the SC value (θ ₁₎ of the gas separation membrane module according to the time progression of the forward-concentration process, the set target enrichment (e ₁₎ The first SC value (? ₁ ) of the first gas separation membrane module is controlled in accordance with the set target concentration (e ₁ ) during the reverse enrichment process to control the flow rate of the permeate gas of the first gas separation membrane module And a second SC value (? ₂ ) of the second gas separation membrane module so that the target gas concentration of the second recovery gas is in accordance with the target gas concentration (X _F ) in the feed gas And a second SC regulator for regulating the second permeable gas flow rate and the second recovered gas flow rate of the second gas separation membrane module.

The bidirectional target gas recovery apparatus includes a bidirectional target gas recovery device and (n + 1) gas storage tanks (n is a natural number). The bidirectional target gas recovery device includes a first gas separation membrane module and a second gas separation membrane module Wherein the n-th concentration step separates the injected gas into a concentrated process permeated gas and a concentrated process recovered gas through each concentration step, and the n-th concentrated process is performed so that the gas stored in the n-th gas storage tank (N-1) gas storage tank, and the n-th concentrated process recovery gas is separated into the n-th concentrated process permeable gas and the n-th concentrated process recovery gas, (2n-1) thickening process (n is a natural number) proceeds in a forward direction, a 2n thickening process (n is a natural number) proceeds in a reverse direction, and the forward direction is stored in a (n + 1) The first stage to the second stage of the gas separation membrane module And the reverse direction is a direction opposite to the forward direction.

The gas recovery apparatus and method according to the present invention have the following effects.

The target gas concentration in the recovery gas can be maximized through the forward concentration process and the reverse concentration process in a state where the number of the gas separation membrane modules to be used is minimized and ultimately the device configuration of the gas recovery device can be simplified.

Further, by setting the second SC value so that the target gas concentration of the second recovered gas matches the target gas concentration of the supplied gas through the configuration of the bidirectional target gas recovery apparatus, the first recovered gas to be finally recovered The gas concentration in the target gas can be maintained constant, and the reliability of the membrane separation process can be improved.

1 is a configuration diagram of a gas recovery apparatus according to an embodiment of the present invention;
2A to 2C are reference views for explaining a concentration process in a gas recovery apparatus according to an embodiment of the present invention.

First, terms used in this specification are defined as follows.

A first recovery gas that is separated from a first gas separation membrane module of a bidirectional target gas recovery device during a n th concentration process;

A second permeate gas separating from the second gas separator module of the bidirectional target gas recovery unit during the n < th > enrichment process.

θ ₁ : First SC value applied to the first gas separation membrane module of the bidirectional target gas recovery device during each concentration process.

θ ₂ : second SC value applied to the second gas separation membrane module of the bidirectional target gas recovery device during each concentration process.

The present invention relates to a bidirectional target gas recovery apparatus to which two gas separation membrane modules are applied, and a bidirectional target gas recovery apparatus that increases the target gas concentration in the recovery gas based on the plurality of gas storage tanks, To be constant.

The concentration process refers to a process of separating the permeated gas and the recovered gas by the bidirectional target gas recovery device. In the present invention, a plurality of concentration processes using the bidirectional target gas recovery device and the plurality of gas storage tanks are sequentially performed do. The concentration of the target gas can be gradually increased by being included in the recovered gas through the sequential progress of the plurality of concentration processes.

In addition, the concentration of the target gas contained in the recovery gas of each concentration process can be maintained constant through the bidirectional target gas recovery device provided with the first gas separation membrane module and the second gas separation membrane module. The bidirectional target gas recovery device includes a first gas separation membrane module and a second gas separation membrane module, separates the injected gas into a first permeation gas and a first recovered gas through a first gas separation membrane module, The separator module separates the first permeable gas of the first gas separation membrane module into a second permeable gas and a second recoverable gas as an injector body and the second recovered gas of the second gas separation membrane module separates the first permeable gas of the first gas separation membrane module It is supplied as a part.

With this configuration, the target gas concentration in the first recovered gas is specified, the first SC value of the first gas separation membrane module is controlled to correspond to the target gas concentration in the first recovered gas, and the target gas concentration The second SC value of the second separation membrane module is controlled so that the second SC value is equal to the target gas concentration in the feed gas. Thus, the target gas concentration in the first recovered gas, that is, the concentration of the target gas contained in the recovered gas in each concentration step, can be kept constant.

Hereinafter, a gas recovery apparatus and method according to an embodiment of the present invention will be described in detail with reference to the drawings.

Referring to FIG. 1, a gas recovery apparatus according to an embodiment of the present invention includes a waste gas supply unit 110, a plurality of gas storage tanks 120, and a bidirectional target gas recovery apparatus 20.

The waste gas supplying unit 110 serves to supply the waste gas containing the target gas to the first gas storage tank 121. The target gas is a gas to be recovered through the gas separation membrane module. As the waste gas including the target gas, waste gas including SF ₆ or waste gas including fluorine gas such as NF ₃ or CF ₄ may be applied. SF ₆ , NF ₃ , CF _4, and the like correspond to the target gas. In the waste gas, a target gas is mixed at a certain concentration. In the following explanation it will be described on the basis of off-gas containing SF _6.

The plurality of gas storage tanks 120 selectively store the permeate gas and the recovered gas generated in each concentration process and supply the stored gas to the bidirectional target gas recovery device 20 to the supply gas.

The concentration process is a process of separating the permeated gas and the recovered gas by the bidirectional target gas recovery device 20 as described above, and the concentration process of the present invention will be described as follows.

In proceeding the plurality of concentration processes, the forward concentration process and the reverse concentration process alternate. In general, when the injection gas is injected into one end of the gas separation membrane module, the recovery gas is recovered through the other end of the gas separation membrane module, that is, the gas recovery is performed in one direction. In the present invention, Two-way gas recovery systems are available, which can be both recovered. In the state where the first gas separation membrane module 230 of the bidirectional target gas recovery device 20 has both ends of the first and second ends, the forward direction means that the first gas separation membrane module Refers to the gas flow in the second direction and the reverse direction refers to the gas flow from the second end to the first end of the first gasket separation module 230 in the opposite direction of the forward direction. A forward feed pressure control device 220 and a forward SC regulator 240 are provided to process the forward gas flow and a reverse feed pressure control device 260 and a reverse SC regulator 270 to process the reverse gas flow, Which will be described later in detail in the description of the bidirectional target gas recovery device 20 to be described later.

In the plurality of concentration steps, the (2n-1) th concentration step (n is a natural number) advances in a forward direction, and the 2n th concentration step (n is a natural number) proceeds in a reverse direction. The plurality of concentration processes will be described in detail as follows.

The gas stored in the first gas storage tank 121 is supplied to the bidirectional target gas recovery apparatus 20 in the forward direction and the supply gas is supplied to the bidirectional target gas recovery apparatus 20, To separate the recovered gas and the permeated gas. In the following description, in the first concentration step, the recovery gas (more precisely, the first recovery gas of the first gas separation membrane module 230) separated by the bidirectional target gas recovery apparatus 20, the permeation gas (more precisely the second gas separation membrane module (The second permeate gas of the second concentration process vessel 280) are referred to as a first enrichment process recovery gas and a first enrichment process permeation gas, respectively, the recovered gas and the permeate gases separated in the n-th enrichment process, respectively, n concentration process. The first concentrated process permeable gas is discharged to the outside and the first concentrated process recovery gas is stored in the second gas storage tank 122. In addition, the first gas storage tank 121 stores a waste gas supplied from the waste gas supply unit 110 and a second concentrated process transparent gas separated in a second concentration process, which will be described later.

2B), the gas stored in the second gas storage tank 122 is supplied to the bidirectional target gas recovery device 20 in the reverse direction, so that the second concentrated process permeated gas and the second concentrated process recovered gas The second concentrated process permeate gas is stored in the first gas storage tank 121 and the second concentrated process recovered gas is stored in the third gas storage tank 123. [ 2C), the gas stored in the third gas storage tank 123 is supplied to the bidirectional target gas recovery apparatus 20, and the third concentration process permeation gas and the third concentration process recovery gas The third enrichment process permeate gas is stored in the second gas storage tank 122 and the third enrichment process recovery gas is stored in the fourth gas storage tank 124.

The relationship between the gas storage tank for supplying the feed gas to the bidirectional target gas recovery apparatus 20 during the respective concentration processes and the gas storage tank for storing the permeated gas separated by the bidirectional target gas recovery apparatus 20 It can be summarized as follows.

In the case of the n-th concentration process (n is a natural number), the gas stored in the n-th gas storage tank is supplied to the bidirectional target gas recovery device 20 to be separated into the n-th concentrated process permeated gas and the n-th concentrated process recovery gas, n concentration process The permeate gas is stored in the (n-1) gas storage tank and the nth concentration process recovery gas is stored in the (n + 1) gas storage tank. However, the first concentrated process permeable gas in the first concentration process is not stored in the gas storage tank but is discharged to the outside.

In the aspect of the type of gas stored in the gas storage tank, the first concentration process recovery gas and the third concentration process permeation gas are stored in the second gas storage tank 122, and the second gas storage tank 123, And the fourth gas storage tank 124 stores the third concentration process recovery gas and the fifth concentration process transmission gas. In summary, the nth concentration process recovery gas and the (n + 2) th concentration process permeation gas are stored in the (n + 1) gas storage tank (n is a natural number). However, the first gas storage tank 121 stores the waste gas supplied from the waste gas supply unit 110 and the second concentrated process transparent gas.

The first concentration step of the first concentration step is carried out through the plurality of concentration steps to the second gas storage tank 122 to the nth gas storage tank The gas to be stored may be a gas separated from the first concentration process recovery gas and the recovery gas separated from the gas stored in the gas storage tank at the previous stage is stored in the gas storage tank at the subsequent stage, The target gas concentration in the recovered gas gradually increases.

The plurality of concentration processes, that is, the first to nth concentration processes may be performed sequentially, or the order of the concentration process may be changed depending on the operating conditions. For example, the gas recovery method may be carried out in the order of the first concentration step, the second concentration step, the nth concentration step, or the first concentration step-the second concentration step-the third concentration step-the first concentration step - It is also possible to proceed by changing the order of the concentration process as the order of the fourth concentration process. For reference, a compressor-type compression device for compressing gas may be further provided at the front end of each of the gas storage tanks.

For reference, although not shown in the drawing, a compressor-type compression device for compressing the gas may be further provided at the front end of each of the gas storage tanks. The compression device may include a gas storage tank The gas discharged from the gas storage tank and supplied to the gas separation membrane module does not pass through the compression device.

Next, the bidirectional target gas recovery device 20 will be described in detail. The bidirectional target gas recovery device 20 basically proceeds through a first gas separation membrane module 230 and a second gas separation membrane module 230. The first gas separation membrane module 230 and the second gas separation membrane module 280) to increase the target gas concentration in the recovered gas. At the same time, it plays a role of maintaining the target gas concentration of the nth concentration process recovery gas separated through each concentration process to be constant. Maintaining the target gas concentration of the n-th concentrated process recovery gas at a constant level may be included in the target gas concentration of the supplied gas supplied to the first gas separation membrane module 230 and in the second recovery gas of the second gas separation membrane module 280 By controlling the second SC value [theta] ₂ so that the target gas concentration of the target gas is equal to the target SC value [theta] ₂ .

The bidirectional target gas recovery apparatus 20 includes a forward gas mixing unit 210, an inverse gas mixing unit 250, a forward supply pressure control unit 220, a reverse supply pressure control unit 260, a first gas separation membrane module 230, a second gas separation membrane module 280, a forward SC regulator 240, and a reverse SC regulator 270.

The forward gas mixing unit 210 may mix the supply gas supplied from one of the plurality of gas storage tanks and the supply gas supplied from one of the plurality of gas storage tanks during the (2n-1) th concentration process (n is a natural number) And the second recovery gas supplied from the second gas separation membrane module 280 is mixed. In addition, the reverse-gas mixing unit 250 may mix the supply gas supplied from one of the plurality of gas storage tanks and the supply gas supplied from one of the plurality of gas storage tanks during the second enrichment process (n is a natural number) 2 gas-separating membrane module 280, as shown in FIG.

The forward supply pressure control device 220 controls the gas of the forward gas mixing part 210 to a predetermined pressure and supplies the gas to the first gas separation membrane module 230. The reverse supply pressure control device 260 Controls the gas of the backward gas mixing unit 250 to a predetermined pressure and supplies the gas to the first gas separation membrane module 230. A compression tank for compressing and storing the mixed gas in front of each of the forward supply pressure control device 220 and the reverse supply pressure control device 260 may be further provided.

The first gas separation membrane module 230 separates the injected gas supplied in a forward or reverse direction into a first permeable gas and a first recovered gas, And serves to separate the first permeable gas of the module 230 into a second permeable gas and a second recoverable gas as an injector body. The first recovered gas separated by the first gasket separating membrane module 230 in progressing each concentration process, that is, the nth concentration process (n is a natural number) through the bidirectional target gas recovering device 20, Concentration process recovery gas, and the second permeable gas separated by the second gas separation membrane module 280 means the above-mentioned n-th concentrated process permeable gas.

The first gas separation membrane module 230 and the second gas separation membrane module (280) is a membrane assembly of a hollow fiber form pores are formed on the _{surface, O 2, N 2, CO} 2 relative to the molecule such as the exception of SF ₆ gas The small size gas permeates the pores of the membrane rapidly and is discharged. The relatively large molecular size SF ₆ is recovered at one end of the membrane without permeating the pores. The gas to be discharged through the pores of the separation membrane is a permeation gas, and the gas recovered from one end of the separation membrane is a recovery gas. At this time, relative to the molecular size of a small gas (O _2, N _2, CO _2, etc.) as well as relative to the molecular size is larger SF ₆ gas is also there is discharged by passing through the pores of the membrane, the permeability of the SF ₆ gas O _2, N ₂ , and CO _2. Therefore, SF ₆ gas can be recovered as a recovered gas, and substantially gases such as O ₂ , N ₂ and CO ₂ are highly permeable gases and SF ₆ gas is a low permeable gas .

The forward SC regulator 240 regulates the first SC of the first gasket separation membrane module 230 according to the target concentration (e ₁ ) set during progress of the forward enrichment process, ie, during the (2n-1) -cut value &thetas; ₁ so as to control the flow rate of the permeate gas and the flow rate of the recovered gas of the first gasket separation membrane module 230. In addition, the reverse SC regulator 270 regenerates the first SC (stage-cut) of the first gasket separator module 230 according to the target concentration (e ₁ ) set during the reverse enrichment process, ) Value θ ₁ to control the flow rate of the permeate gas and the flow rate of the recovered gas of the first gasket separation membrane module 230.

The first SC value θ ₁ controlled by the forward SC controller 240 and the reverse SC controller 270 is the ratio of the inlet gas flow rate to the permeate gas flow rate as shown in Equation 2 below. For example, if the SC value is 0.95, then the permeate flow rate versus the inlet gas flow rate is 95% and the recovered gas flow rate is 5%, which means that 5% of the total injected gas is recovered (see Equations 1 and 2) .

(Formula 1) Injected gas flow rate (F _f ) = permeate gas flow rate (F _p ) + recovered gas flow rate (F _r )

(Equation 2) SC = permeable gas flow rate (F _p ) / injected gas flow rate (F _f )

In the present invention, the first SC value (? ₁ ) of each concentration step is controlled according to the target concentration (e ₁ ) set in each concentration step. The target concentration (e) means the ratio of the target gas concentration (X _R ) in the first recovered gas to the target gas concentration (X _F ) in the supplied gas (see Equation 3). The target concentration (e) can be calculated by setting the target gas concentration (X _R ) in the first recovered gas in a state where the target gas concentration (X _F ) in the supplied gas is determined. The target gas concentration (X _R ) in the first recovered gas may be the concentration of the target gas to be recovered through the bidirectional target gas recovery device 20 in each concentration step, and the concentration of the target gas in the forward SC regulator 240 and the reverse SC regulator 270, respectively.

On the other hand, the first SC value (? ₁ ) applied to each concentration step is set to become smaller as the concentration step proceeds. The reason is that, as described above, in the first concentrated process permeated gas separated in the first concentration process, the subsequent thickening process is performed based on the first concentrated process recovered gas, and the gas stored in the gas storage tank The recovered gas separated from the gas stored in the gas storage tank is stored in the gas storage tank at the downstream stage. As the concentration process proceeds, the flow rate of the recovered gas becomes relatively large and the flow rate of the permeated gas becomes relatively small.

(Eq. 3) Target concentration (e) = X _R / X _F

(where e is the target concentration, X _F is the target gas concentration in the injected gas, and X _R is the target gas concentration in the recovered gas)

When the target concentration (e ₁ ) of the first gas separation membrane module 230 is set, the first SC value (? ₁ ) is calculated through the following equation (4). The target gas concentration X _{F in the} feed gas and the selectivity? ₁ of the first gas separation membrane module 230 are required in addition to the target concentration (e ₁ ) in order to calculate the first SC value? ₁ .

The injected gas injected into the first gas separation membrane module 230 includes the second recovered gas of the second gas separation membrane module 280 in addition to the feed gas. Therefore, the target gas concentration information in the second recovery gas must be reflected in addition to the target gas concentration (X _F ) in the feed gas when calculating the first SC value (? ₁ ). In the present invention, the target gas concentration in the second recovery gas controlled to match the target gas concentration (X _F) in the feed gas and to, any one of claim 1 SC value (θ ₁₎ the target gas concentration in the target gas concentration (X _F) or the second number of the gas in the feed gas to the calculation formula of It is possible to calculate the first SC value (? ₁ ) even if only one piece of information is applied. The reason why the target gas concentration in the second recovered gas is controlled to coincide with the target gas concentration (X _F ) in the supplied gas is to keep the target gas concentration in the first recovered gas constant.

The selectivity α ₁ of the first gas separation membrane module 230 means the ratio of the permeability P _A of the permeable gas to the permeability P _B of the target gas, And the selectivity of the second gas separation membrane module 280 may be the same or different.

(Equation 4)

(θ ₁ is the target enrichment, X _F is the target gas concentration in the feed gas, α ₁ of the first gas separation membrane module (first SC value, e ₁ is a first gas separation membrane module 230 to be applied to 230) is the 1 Selection of gas separation membrane module 230)

(Expression 5)? ₁ = P _A / P _B

(? ₁ is the selectivity of the first gasketing membrane module 230, P _B is the permeability of the target gas, and P _A is the permeability of the permeable gas)

On the other hand, the supply gas supplied from each gas storage tank is set to be supplied at a constant flow rate, but is varied in real time due to various factors such as equipment condition, temperature and pressure on the supply gas supply unit side. If the SC value is specified, the flow rate of the permeated gas and the recovered gas separated by the first gas separation membrane module 230 and the second gas separation membrane module 280 are affected. That is, if the flow rate of the feed gas is changed, the flow rate of the permeated gas and the recovered gas can not be maintained constant.

In order to cope with the change in the flow rate of the supply gas, it is necessary to vary the supply pressure of the injection gas injected into the first gasket separation membrane module 230 in accordance with the change in the flow rate of the supply gas. Specifically, the supply pressure P of the forward supply pressure control device 220 or the reverse supply pressure control device 260 can be set as shown in Equation 6 below. That is, when a change occurs in the flow rate of the supply gas, the flow rate change ratio v / v _o of the supply gas is multiplied by the initial supply pressure P _o so that the forward supply pressure control device 220 or the reverse supply pressure control device 260 ) Is set. Although not shown, a second supply pressure control device for controlling the pressure of the injection gas (first permeable gas) injected into the second gasket separation membrane module 280 is provided at the front end of the second gasket separation membrane module 280 And the supply pressure of the second supply pressure control device is set equal to the supply pressure of the forward supply pressure control device 220 or the reverse supply pressure control device 260 in which the process proceeds.

(Equation 6)

(P is a real-time setting forward supply pressure control device 220 or the reverse feed supply pressure of the pressure control device 260 is, v is the flow rate of the feed gas that is real-time changes, v _o is the flow rate of the first feed gas, P _o is the forward The initial supply pressure of the supply pressure control device 220 or the reverse supply pressure control device 260)

Meanwhile, the second SC regulator 290 controls the second gas separator module 280 such that the target gas concentration Y _R in the second recovery gas of the second gas separation membrane module 280 matches the target gas concentration X _F in the supply gas, And controls the second SC value (? ₂ ) of the module (280).

A second calculator for calculating the SC value (θ ₂₎ expression by default, the 1 SC value the same as the calculation equation (Equation 4) (θ _1), the 1 SC value (θ ₁₎ is also the target concentration of the calculation formula (e ₁ ) instead of the target concentration (e ₂ ) of the second gas separation membrane module 280. The first is applicable to replace even (α ₁₎ instead of Figure (α ₂₎ selection of the second gas separation membrane module, the selection of a gas separation membrane module (230).

The target concentration of the second gasketing membrane module 280 is determined such that the target concentration e ₁ of the second gasketing membrane module 280 is less than the target concentration e ₁ of the second gasketing membrane module 280, Is set to the ratio of the target gas concentration (Y _R ) in the second recovery gas to the target gas concentration (Y _R ) in the second recovery gas. Further, in the present invention, as the target gas concentration (Y _R ) in the second recovered gas is set to coincide with the target gas concentration (X _F ) in the feed gas, the target enrichment degree e ₁ ) Can be set to the ratio of the target gas concentration (X _F ) in the supply gas to the target gas concentration (Y) in the first transmission gas as shown in the following equation (7).

(Equation 7) e ₂ = Y _R / Y = X _F / Y

(where e ₁ is the target concentration of the second gas separation membrane module 280, Y is the target gas concentration in the first permeable gas, Y _R is the target gas concentration in the second recovered gas, and X _F is the target gas concentration in the feed gas)

Thus, the first even target concentration of Equation SC value (e ₁₎ instead of the target in the second gas separation membrane is applied to the target concentration of the module 280. Fig. (E ₂₎ is replaced, the first feed gas of Equation SC value The calculation formula of the second SC value (? ₂ ) to which the target gas concentration (Y) in the first transparent gas is applied instead of the gas concentration (X _F ) is shown in the following equation (8). Then, the calculation formula of the second SC value (? ₂ ) through the derivation process of Equation (9) is finally expressed as Equation (10). If the selectivities of the first gas separation membrane module 230 and the second gas separation membrane module 280 are the same, the second SC value (? ₂ ) calculation expression is expressed by Expression 11.

(Expression 8)

( _{2 2} is a second SC value, y ₁ is a target gas concentration in the first permeable gas, X _F is a target gas concentration in the supplied gas, and? ₂ is a selectivity of the second gasketing membrane module 280)

(Equation 9)

(Equation 10)

(? ₂ is the second SC value, X _F is the target gas concentration in the feed gas,? ₁ is the selectivity of the first gasketing membrane module 230,? ₂ is the selectivity of the second gasketing membrane module 280)

(Expression 11)

(? ₂ is the second SC value, X _F is the target gas concentration in the feed gas,? ₁ is the selectivity of the first gas separation membrane module 230 and the second gas separation membrane module 280)

It is possible to calculate the second SC value satisfying that the target gas concentration of the second recovered gas coincides with the target gas concentration in the feed gas through the above-described second SC value (? ₂ ) calculating formula, The SC value [theta] ₂ is applied to the operation of the second gas separation membrane module 280. [

Thus, as the target gas concentration of the second recovered gas supplied to the gas mixing portion through the control of the second SC value (? ₂ ) coincides with the target gas concentration (X _F ) of the supplied gas, The target gas concentration of the injected gas injected into the first gas separation membrane module 230 is maintained constant and the target gas concentration of the first recovered gas collected by the first gas separation membrane module 230 can be stably and constantly maintained.

The configuration of the bidirectional target gas recovery device 20 has been described above.

On the other hand, when proceeding with the plurality of concentration processes, the optimum operation time of each concentration process can be set. First, the optimum operation time of the first concentration step will be summarized as follows.

The volume V _in of the waste gas flowing into the first gas storage tank 121 and the volume V _{in of} the first gas storage tank 121 to the bidirectional target gas recovery device 20 during the operation time T ₁ of the first concentration process The volume V _out of the supplied gas is set as shown in Equations 12 and 13 below. Based on equations (12) and (13), the volume reduction amount (V _out -V _in ) _in the first gas storage tank (121) at the completion of the first concentration step is summarized as shown in Equation (14).

The pressure in the first gas storage tank 121 is the highest at the start of the first concentration process (P _{1, max} ), and the volume in the first gas storage tank 121 is C ₁ · P _{1, max} (C ₁ is the capacity of the first gas storage tank 121). The gas volume in the first gas storage tank 121 is gradually decreased and thus the gas pressure in the first gas storage tank 121 is also reduced. In the first gas storage tank 121, When the gas pressure in the first gas storage tank 121 is lower than the supply pressure P ₀ to the gas separation membrane module, the gas supply to the bidirectional target gas recovery device 20 is not advanced, The minimum volume should be greater than C ₁ · P ₀ . Therefore, the maximum reduction amount (V _{oi, max} ) of the gas in the first gas storage tank 121 at the time of the first concentration process can be summarized as shown in Equation (15).

Under such a summary, the volume reduction amount V _out -V _{in in} the first gas storage tank 121 at the time of completion of the first concentration process is smaller than the volume reduction amount V _out -V _{in in} the first gas storage tank 121 It is equal to or less than the maximum decrease amount (V _{oi, max),} and (see equation 16), the optimum driving time of the first concentration step satisfying such condition may be set as shown in equation 17.

(Expression 12)

(V _in is the volume of the waste gas flowing into the first gas storage tank 121 during the operation time of the first condensation process, T ₁ is the operation time of the first condensation process, and f ₀ is the flow rate of the waste gas in the first condensation process)

(Expression 13)

(V _out is the volume of the injected gas supplied from the first gas storage tank 121 to the gas separation membrane module during the operation time of the first concentration process, T ₁ is the operation time of the first concentration process, f _F, Flow rate of injected gas during concentration process)

(Equation 14)

(Expression 15)

(V _{oi, max} is the maximum reduction amount of the gas in the first gas storage tank 121, C ₁ is the capacity of the first gas storage tank 121, and P _{1, max} is the volume of the first gas storage tank 121) (P ₀ ) is the maximum gas pressure in the first gas separation membrane module (121), and P ₀ is the supply pressure of the injection gas supplied to the first gas separation membrane module (230)

(Expression 16)

(Equation 17)

(T ₁ is the operating time of the first concentration step, C ₁ is the first gas capacity of the storage tank 121, P _{1, max} is the maximum gas pressure, P ₀ is the first gas in the first gas storage tank (121) _{F F, 1} is the flow rate of the injected gas in the first concentration step, f ₀ is the flow rate of the offgas in the first concentration step)

The optimum operation time of the first concentration step has been described above. It is also possible to set the optimum operation time for the n th concentration step other than the first concentration step. (N is a natural number of 2 or more) for the n-th concentration process (n is a natural number of 2 or more), and the n-th storage tank (n is a natural number of 2 or more) , The flow rate (f ₀ ) of the waste gas is omitted from the variables.

(Expression 18)

C _n is the capacity of the first gas storage tank 121, and P _{n, max} is the maximum gas pressure in the first gas storage tank 121 (T _n , n is a natural number of 2 or more) , P ₀ is the supply pressure of the injected gas supplied to the first gasketing membrane module 230, f _{F, n} is the flow rate of the injected gas during the n th concentration process)

The flow rate (f _{F, 1} ) of the injected gas in the first concentration step and the flow rate (f _{F, n} ) of the injected gas in the n th concentration step applied to the above Equation 17 and Equation 18 are summarized as in Equations 19 and 20, respectively .

(Expression 19)

(f _{F, one} of the first concentrate flow rate of the process when the injection gas, θ ₁ is the first first SC value of the concentration process, A is the membrane area, P ₀ of the first gas separation membrane module 230 comprises a first gas separation membrane P _A is the permeability of the permeable gas, P _B is the permeability of the target gas, and x ₀ is the target gas concentration in the waste gas)

(Expression 20)

(f _{F, n} (n is a natural number) is the flow rate of the injected gas during the n-th concentration step, θ _n is the first SC value of the n concentration process, A is the membrane area of the first gas separation membrane module (230), P ₀ P _A is the permeability of the permeable gas, P _B is the permeability of the target gas, and x _n is the permeability of the first gasketing membrane module 230 in the n th concentration process, Target gas concentration in the injected gas injected into the target gas)

The flow rate (f _{F, 1} ) of the injected gas in the first concentration step may be summarized in the following equation (21) in terms of the relationship between the waste gas flow rate (f ₀ ) and the operation time (T _i ) of the concentration step. The following equation 21 is the total volume of gas to be treated through a plurality of the concentration process of gas recovery apparatus of the present invention (f ₀ · ΣT _i) the volume of the injected gas to be injected into the gas separation membrane module during the operation time of the first concentration step (f _{F, 1} · T ₁ ).

(Expression 21)

(f _{F, 1} is the flow rate of the injected gas in the first concentration step, f ₀ is the waste gas flow rate, ΣT _i is the sum of the operation times of the plurality of concentration steps, and T ₁ is the operation time of the first concentration step)

110: waste gas supply unit 120: a plurality of gas storage tanks
121: first gas storage tank 122: second gas storage tank
123: Third gas storage tank 124: Fourth gas storage tank
20: Bi-directional target gas recovery device
210: Forward gas mixing part 220: Forward feed pressure control device
230: first gas separation membrane module 240: forward SC regulator
250: Reverse gas mixing part 260: Reverse feed pressure control device
270: Reverse SC regulator 280: Secondary gas separation membrane module
290: Second SC regulator

Claims (13)

The first gas separation membrane module and the second gas separation membrane module, wherein the n concentration process (n is a natural number) is performed, and the purged gas is separated into the concentrated process recovered gas and the concentrated process permeated gas through each concentration process A bidirectional target gas recovery device; And
(n + 1) gas storage tanks,
The n < th >
The gas stored in the n-th gas storage tank is supplied to the gas separation membrane module and separated into the n-th concentrated process permeated gas and the n-th concentrated process recovery gas, and the n-th concentrated process permeated gas is stored in the (n-1) And the nth concentration process recovery gas is stored in the (n + 1) gas storage tank,
The (2n-1) th thickening step proceeds in the forward direction, the (2n) th thickening step proceeds in the reverse direction,
Wherein the forward direction is a gas flow from a first end to a second end of the first gas separation membrane module, and the reverse direction is a direction opposite to the forward direction.
2. The gas recovery apparatus according to claim 1, wherein the n-th recovered gas and the (n + 2) -th transparent gas are stored in the (n + 1) -th gas storage tank.
The apparatus according to claim 1, further comprising a waste gas supply unit for supplying waste gas containing a target gas to the first gas storage tank,
The first gas storage tank stores the waste gas supplied from the waste gas supply unit and the second concentrated process permeable gas, and the first concentrated process permeable gas of the first condensation process is discharged to the outside.
2. The method according to claim 1, wherein the operation time (T ₁ ) of the first concentration step satisfies the following expression ( ₁ ), and the operation time (T _n ) of the nth concentration step (n is a natural number of 2 or more) And the gas recovery device satisfies the following condition.
(Equation 1)

(Where T ₁ is the operating time of the first concentration step, C ₁ is the capacity of the first gas storage tank, P _{1, max} is the maximum gas pressure in the first gas storage tank, P ₀ is the pressure of the inlet gas supplied to the gas separation membrane module ₁ is the flow rate of the injected gas in the first concentration step, and f ₀ is the flow rate of the used gas in the first concentration step)
(Equation 2)

(T _n (n is a natural number of 2 or more) is the n-th operation period, C _n is the first capacity of the gas storage tank of the concentration step, P _{n, max} is the first maximum gas pressure in the gas storage tank, P ₀ is a gas separation membrane The supply pressure of the injection gas supplied to the module, f _{F, n} is the flow rate of the injection gas in the n th concentration process)
2. The bidirectional target gas recovery system as claimed in claim 1,
A forward gas mixing unit for mixing a supply gas supplied from a gas storage tank among the plurality of gas storage tanks and a second recovery gas supplied from the second gas separation membrane module during a forward enrichment process,
A reverse gas mixing unit for mixing the supply gas supplied from any of the gas storage tanks of the plurality of gas storage tanks and the second recovery gas supplied from the second gas separation membrane module during the reverse concentration step,
A first gas separation membrane module for separating an injection gas supplied in a forward or reverse direction into a first permeation gas and a first recovery gas in accordance with a first SC value (? ₁ )
And a second gas separation membrane module for separating the first permeable gas of the first gas separation membrane module into a second permeable gas and a second recovered gas according to a second SC value (θ ₂ )
And a second SC value (? ₂ ) is set so that the target gas concentration of the second recovered gas is coincident with the target gas concentration of the supplied gas.
6. The gas recovery apparatus according to claim 5, wherein the second SC value (? ₂ ) is calculated by the following equation.
(expression)

(? ₂ is the second SC value, X _F is the target gas concentration in the feed gas,? ₁ is the selectivity of the first gas separation membrane module, and? ₂ is the selectivity of the second gas separation membrane module)
6. The gas recovery apparatus according to claim 5, wherein the second SC value (? ₂ ) is calculated by the following equation.
(expression)

(θ ₂ is a second SC value, X _F is a target gas concentration in the feed gas, and α ₁ is a selectivity of the first gas separation membrane module and the second gas separation membrane module)
6. The gas recovery apparatus according to claim 5, wherein the first SC value (? ₁ ) is calculated through the following equation.
(expression)

(θ ₁ is selected in the first SC value, e ₁ is a first gas separation membrane module, the target gas concentration, α ₁ is a first gas separation membrane modules in the target concentration in Fig, X _F is the feed gas that is applied to a first gas separation membrane module Degree)
The apparatus according to claim 5, further comprising: a forward supply pressure control device for controlling the gas of the forward gas mixing part to a predetermined pressure and supplying the gas to the first gas separation membrane module; Further comprising a reverse feed pressure control device for feeding the feed gas to the membrane module.
6. The method of claim 5,
When proceeding concentration step of the forward, it sets target enrichment (e ₁₎ by the first control to the first SC value (θ ₁₎ of the gas separation membrane module according to to control the transmission gas flow rate and the number of times the gas flow rate of the first gas separation membrane module A forward SC regulator,
When proceeding concentration process in the reverse direction, the set target enrichment (e ₁₎ by the first control to the first SC value (θ ₁₎ of the gas separation membrane module according to to control the transmission gas flow rate and the number of times the gas flow rate of the first gas separation membrane module A reverse SC regulator,
The second SC value (? ₂ ) of the second gas separation membrane module is controlled so that the target gas concentration of the second recovered gas coincides with the target gas concentration (X _F ) in the feed gas, And a second SC regulator for regulating the second recovered gas flow rate.
Way target gas recovery device and (n + 1) gas storage tanks (n is a natural number)
The bidirectional target gas recovery device includes a first gas separation membrane module and a second gas separation membrane module, and performs n concentration processes. Through the respective concentration processes, the target gas is converted into a concentrated process permeated gas and a concentrated process recovery gas Separating,
The n < th >
The gas stored in the n-th gas storage tank is supplied to the gas separation membrane module and separated into the n-th concentrated process permeated gas and the n-th concentrated process recovery gas, and the n-th concentrated process permeated gas is stored in the (n-1) And the nth concentration process recovery gas is stored in the (n + 1) gas storage tank,
The (2n-1) th concentration step (n is a natural number) proceeds in a forward direction, the 2n th concentration step (n is a natural number) proceeds in a reverse direction,
Wherein the forward direction is a gas flow from a first end to a second end of the first gas separation membrane module, and the reverse direction is the opposite direction of the forward direction.
12. The method according to claim 11, wherein the first transparent gas in the first concentration step is discharged to the outside,
Wherein the first gas storage tank stores the waste gas supplied from the waste gas supply unit and the second concentrated process transparent gas.
12. The bidirectional target gas recovery system according to claim 11,
A forward gas mixing unit for mixing a supply gas supplied from a gas storage tank among the plurality of gas storage tanks and a second recovery gas supplied from the second gas separation membrane module during a forward enrichment process,
A reverse gas mixing unit for mixing the supply gas supplied from any of the gas storage tanks of the plurality of gas storage tanks and the second recovery gas supplied from the second gas separation membrane module during the reverse concentration step,
A first gas separation membrane module for separating an injection gas supplied in a forward or reverse direction into a first permeation gas and a first recovery gas in accordance with a first SC value (? ₁ )
And a second gas separation membrane module for separating the first permeable gas of the first gas separation membrane module into a second permeable gas and a second recovered gas according to a second SC value (θ ₂ )
And a second SC value (? ₂ ) is set so that a target gas concentration of the second recovered gas is coincident with a target gas concentration of the supplied gas.

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