TWI579034B - A combined membrane - pressure swing adsorption method for the recovery of helium - Google Patents

Description

Combined membrane for pressure recovery - pressure swing adsorption

This invention relates to a process for recovering hydrazine from process gases.

Various methods for extracting or recovering cerium (especially pure cerium) from cerium-containing gas or concentrating to increase the cerium content are known in the prior art. For example, EP 1 427 508 A1 discloses a combined membrane-adsorption method for recovering rhodium. Among them, the hydrazine used (especially pure hydrazine) is contaminated during use. The contaminated cockroaches are then adsorbed and purified.

No. 5,632,803 A discloses a method in which, in a first step, a helium-enriched permeate stream is extracted from a process gas having a higher pressure by a membrane separation stage. Next, the permeate stream is concentrated to a cerium content of about 50 vol% in the first pressure swing adsorption. The ruthenium product having a purity of more than 95 vol% is then extracted from the concentrated stream by second pressure swing adsorption.

Methods for using pure adsorption or pure low temperature solutions are also known. These methods are often used only for concentration.

Tantalum plays an important role in many applications, but usually only exists in a dilute form, such as in natural gas or flushing gases used in various production methods. Since it is a limited raw material, the economic significance of the method for extracting or recovering hydrazine is increasing. Therefore, it is necessary to find a method capable of simultaneously extracting (recycling) hydrazine in high purity and high yield.

In view of the above, it is an object of the present invention to provide a method which is preferably capable of simultaneously extracting ruthenium in high purity and high yield. Features of the present invention are contained in separate items, and advantageous technical solutions are disclosed by the respective sub-items, which will be described below. The characteristics of the patent application scope can be any A technically meaningful way of combining the methods, the features included in the following description and the features in the drawings include complementary technical solutions of the present invention, which may also be supplemented.

The solution of the invention for achieving this object is a method for extracting rhodium from a rhodium-containing process gas, which is carried out, in particular, using the apparatus of the invention, and which has at least the following steps: a. low pressure The helium-containing process gas at 15 bar, preferably less than 10 bar, is delivered to a compression device that compresses the process gas by a compressor before the process gas is introduced into the first membrane separation stage. Specifically, there is no other compressor in the device; b. The process gas discharged from the compression device is sent to a pre-purification unit, and interference components such as SF6 or NF3, metal hydride, etc. are removed in the pre-purification unit. And c. introducing the process gas from which the interfering component has been removed into the first membrane separation stage having the first membrane, and at least one other component (eg, nitrogen, CO ₂ , Ar, O ₂ included in the process gas) , methane, see also above), the first membrane is more susceptible to osmosis, wherein a first retentate stream and a first permeate stream are produced, wherein the first retentate stream is poor and the first permeate stream is rich; d. introducing a first retentate stream having a component that has been intercepted by the first membrane into a second membrane separation stage having a second membrane, and at least one other component (eg, nitrogen and/or included in the process gas) Or methane, see above), the second membrane is more susceptible to osmosis, wherein a second retentate stream and a second permeate stream are produced, wherein the second retentate stream is poor and the second permeate stream is rich; e. Separating from the first ruthenium permeate stream having a component that has penetrated the first membrane by pressure swing adsorption And producing a cerium-containing product stream having a high cerium content, in particular; and f. returning the second cerium-containing permeate stream having a component that has penetrated the second membrane to the first membrane separation stage, and The flushing gas of the pressure swing adsorption device is returned to the first membrane separation stage, wherein the flushing gas is specifically used to flush the adsorber used in the pressure swing adsorption.

Of course, the two membrane separation stages can also be operated by purge gas. For this purpose, for example, a purge gas inlet can be provided on each of the respective permeate sides.

The at least one membrane of each membrane separation stage is more susceptible to permeation by the crucible than at least one other component contained in the process gas stream. The permeation rate of each membrane is preferably the highest, and the permeability of all other components of the process gas is low. Such other components or corresponding gas molecules may especially be nitrogen (N ₂ ), carbon dioxide (CO ₂ ), argon (Ar), oxygen (O ₂ ) or methane (CH ₄ ). Correspondingly, the permeate flow is rich and the stagnant flow is poor.

According to an advantageous embodiment, the process gas is further conveyed through a pre-purification unit for removing components of the process gas that interfere with subsequent processes. The pre-purification unit is disposed downstream of the compressor and upstream of the first membrane separation stage. The prepurification unit preferably has at least one of the following functional units: a temperature swing adsorption unit, a reactor for performing a reaction to remove one or several interfering components (eg, non-renewable adsorption or chemisorption units, from the process gas, The so-called guard bed (Guard-Bett).

In principle, however, it is also possible to use a catalyst to carry out the reaction of minor components (for example H ₂ , SiH ₄ , oxidation of hydrocarbons).

The prepurification unit is preferably used to separate at least one of the following interference components: H ₂ , hydrocarbons, H ₂ O, CO ₂ , ammonia, sulfur compounds, fluorinated gases (SF6, NF3), decane, phosphine/arsenic Hydrogen, halogenated hydrocarbons (CF4, etc.), such as metal hydrides for chemical vapor deposition and alternative methods, and the like.

To remove impurities for adsorption, one or several non-renewable adsorbers (so-called guard beds) are used upstream of the first membrane separation stage as pre-purification units. Alternatively, a temperature swing adsorption unit (TSA) having at least two adsorbers can be used. Wherein, the process stream is first introduced into the first adsorber to adsorb the interference component. Other adsorbers are regenerated or Standby. The gas discharged from the first adsorber can be directed to the next non-renewable adsorber (guard bed) to achieve high bed utilization while achieving high purity (Bettausnutzung). By before the membrane separation stage A pre-cleaning unit (TSA and/or guard bed) is placed to prevent contamination of the membrane.

Preferably, the method of the present invention uses two membrane separation stages, specifically two membrane separation stages, wherein preferably only the first membrane separation stage is arranged to be placed before the pressure swing adsorption unit to provide the helium containing gas from The recovered product gas is (pure) hydrazine. The second membrane separation stage preferably provides a permeate gas that can be returned to the first membrane separation stage.

Therefore, a first retentate flow line is provided between the first membrane separation stage and the second membrane separation stage, which connects the first retentate outlet of the first membrane separation stage to the second product gas inlet of the second membrane separation stage stand up.

A first permeate flow line is provided between the first membrane separation stage and the pressure swing adsorption unit, which connects the first permeate outlet of the first membrane separation stage to the third product gas inlet of the pressure swing adsorption unit. In this case, the pressure swing adsorption unit has at least two adsorbers, so that one adsorber can always be operated in the adsorption mode and the other adsorbent can be regenerated, for which purpose the pressure in the adsorber is lowered and flushed. The gas is flushed by the adsorber. This allows the adsorption program to be run continuously. Other modes of operation are also possible.

Providing at least one (second) permeate stream from the second membrane separation stage to the feed line or the first membrane separation stage between the second permeate outlet of the second membrane separation stage and the feed line A return line. That is, the second permeate stream is fed to the process stream to correspondingly increase the niobium content of the process stream fed to the first membrane separation stage. A second return line for delivering flushing gas to the process gas is provided between the flushing gas outlet and the feed line or the first return line. This greatly increases the yield; since the enthalpy enters the exhaust gas when the adsorber is regenerated, this portion of the enthalpy is lost if it is not returned. The second retentate outlet discharges the gas component that does not penetrate the at least one second membrane or that ultimately stays on the second retention side as exhaust gas. This component has only a very low cerium content, preferably less than 0.1 vol%.

In the first membrane separation stage, the permeate stream preferably has a niobium content of 20 vol% or more. Next, the pressure swing adsorption apparatus achieves a niobium content of more than 95 vol%, preferably more than 99 vol%. Preferably, polyimine (PI), polyfluorene (PSf) or polyarylamine (PA) is used as the first and second films. The membrane material of the membrane of the separation stage. The temperature in the two membrane separation stages and the temperature of the pressure swing adsorption unit and the temperature swing adsorption unit are preferably in the range of 0 ° C to 120 ° C, preferably in the range of 20 ° C to 60 ° C. The inlet stream of the two membrane separation stages and the inlet stream of the temperature swing adsorption unit preferably have a pressure in the range of 10 to 80 bar, preferably in the range of 15 to 60 bar. The inlet flow of the pressure swing adsorption device preferably has a pressure in the range of 5 to 20 bar. In particular, the outlet pressures are respectively 0 to 3 bar lower than the corresponding inlet pressures.

In the second membrane separation stage, most of the enthalpy of the retentate stream of the first membrane separation stage is separated as a permeate stream, thereby achieving a high yield or a retentate stream with very low hydrazine content being discharged from the process. The method is particularly useful for recovering helium from process gases and exhaust streams having atmospheric pressure or preferably low overpressure of up to 15 bar. The method is particularly suitable for recovering helium from exhaust streams produced by processes in the electronics and semiconductor industries.

Wherein, preferably, the return flow (second permeate flow) from the second membrane separation stage and the return flow (flush gas) from the pressure swing adsorption unit are fed to the feed line of the first membrane separation stage upstream of the compressor. .

The method proposed in the present invention is particularly suitable for implementation in the foregoing manner on the apparatus or crucible recovery apparatus of the present invention. The method is characterized in that the second permeate stream and the flushing gas stream of the second membrane are returned from the pressure swing adsorption unit to the first membrane separation stage.

Among them, the first permeate stream having a niobium content of 25 vol% or more is preferably produced in the first membrane separation stage. A product gas or helium gas having a purity of 95 vol% or more, preferably 99 vol% or more, is produced at the product gas outlet of the pressure swing adsorption apparatus. In addition, the second stranded stream is specifically discarded or used for other purposes (see below).

According to another advantageous embodiment of the method, (specifically only) the process gas is compressed upstream of the first membrane separation stage (preferably compressed to a pressure in the range from 15 bara to 60 bara). That is, the method of the present invention requires only (depending on the multi-stage) compression of the process gas. Therefore, the investment cost and operating cost of the method are correspondingly low.

According to another advantageous embodiment of the method, upstream of the first membrane separation stage and specific Downstream of the compression device described above, the interfering components that may be present in the process gas are removed, preferably by a temperature swing adsorption device and/or other reactions (eg, in an adsorber and/or reactor).

According to another advantageous embodiment of the method according to the invention, the process gas for the recovery of the crucible is a process exhaust gas for the production of electronic components and/or semiconductor components, wherein in particular the separation process is carried out during the aforementioned prepurification At least one of the following components of the gas: H ₂ , hydrocarbons, H ₂ O, CO ₂ , sulfur compounds, decane, phosphine/arsenic hydrogen, halogenated hydrocarbons, fluorinated gases (SF6, NF3), metal hydrides and many more.

According to another advantageous embodiment of the method of the invention, the second retentate stream having the components that have been intercepted by the second membrane is used to regenerate one (or several) of the adsorbers used in the temperature swing adsorption unit (see above). In addition, the second retentate stream that does not penetrate the second membrane may specifically expand to perform work in the presence of electrical energy.

In returning the second permeate stream to the first membrane separation stage and returning the purge gas to the first membrane separation stage, it is not necessary to return all of the respective streams as appropriate. It is also possible to return only one split to the first membrane separation stage.

In the following, the invention will be described in detail in conjunction with the drawings and the preferred embodiments illustrated herein.

1‧‧‧氦Separation equipment

2‧‧‧First membrane separation stage

3‧‧‧Second membrane separation stage

4‧‧‧First film

5‧‧‧second film

6‧‧‧First retention side

7‧‧‧Second stranded side

8‧‧‧First Process Gas Inlet

9‧‧‧Second process gas inlet

10‧‧‧First stranded outflow

11‧‧‧Second stranded outflow

12‧‧‧First infiltration side

13‧‧‧Second infiltration side

14‧‧‧First permeate outlet

15‧‧‧Second permeate outlet

16‧‧‧ Pressure swing adsorption unit

17‧‧‧ Third Process Gas Inlet

18‧‧‧ flushing gas outlet

19‧‧‧Product gas export

20‧‧‧feed line

21‧‧‧Product gas pipeline

22‧‧‧Compressor level

23‧‧‧Pre-cleaning unit

24‧‧‧氦Recycling equipment

25‧‧‧Production line

26‧‧‧First stranded flow line

27‧‧‧First permeate flow line

28‧‧‧First return line

29‧‧‧Second return line

30‧‧‧First exhaust gas pipeline

31‧‧‧Second exhaust gas pipeline

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a diagram of a method of separating rhodium from a process gas and a crucible separation apparatus of the present invention in accordance with the present invention.

Figure 1 shows an apparatus 1 of the invention. If the process gas to be treated is an exhaust gas from a manufacturing process or line 25 that is particularly useful for the manufacture of electronic components and/or semiconductor components, the device is also referred to as a recovery device 24 and may include the manufacturing process or line 25.

The process gas or offgas is delivered by feed line 20 to compressor 22 where it is compressed and pre-purified downstream of compressor 22, particularly by temperature swing adsorption unit 23. Connect The pre-purified process gas is delivered to the first membrane separation stage 2 through the first process gas inlet 8 as it is, i.e., to the first retention side 6. A process gas component having a higher cerium content can penetrate the first membrane 4, the process gas component reaching the first permeate side 12 where it is discharged as a first permeate stream through the first permeate outlet 14 and is passed by the first permeate stream The line 27 is introduced into the pressure swing adsorption unit 16.

The process gas component that has not penetrated the first membrane 4 or the final membrane 4 in the first membrane separation stage 2 stays on the first retention side 6 and is discharged through the first retention flow outlet 10 as the first retention flow. Subsequently, the first retentate stream is introduced by the first retentate stream line 26 through the second process gas inlet 9 into the second membrane separation stage 3, i.e., to the second retentate side 7. The process gas penetrating the second membrane 5 reaches the second permeate side 13 and flows through the second permeate outlet 15 as a second permeate stream into the first return line 28, and the second permeate stream is re-delivered to the first return line to Feed line 20 or first membrane separation stage 2, preferably upstream of compressor 22.

The process gas component that does not penetrate the second membrane 5 in the second membrane separation stage 3 is discharged as a second retentate flow through the second retentate outlet 11 and the first exhaust gas line 30. This (low enthalpy) exhaust gas can be used in particular to flush the adsorber of the temperature swing adsorption unit 23.

The first permeate stream is introduced into the pressure swing adsorption unit 16 from the first permeate stream line 27 through the third process gas inlet 17. The flushing gas generated during the pressure swing adsorption process is again sent to the feed line 20 or the first membrane separation stage 2 through the second return line 29 (here by the first return line 28) through the flushing gas outlet 18, That is, it preferably reaches the upstream of the compressor 22. The first permeate stream which is further purified by pressure swing adsorption is discharged as a product gas or a pure helium gas having a niobium content of preferably more than 95 vol%, particularly preferably more than 99 vol%, and is transported by the product gas line 21 as a product gas. He used it. The residual gas of the temperature change adsorption device 23 is discharged through the second exhaust gas line 31.

1‧‧‧氦Separation equipment

2‧‧‧First membrane separation stage

3‧‧‧Second membrane separation stage

4‧‧‧First film

5‧‧‧second film

6‧‧‧First retention side

7‧‧‧Second stranded side

8‧‧‧First Process Gas Inlet

9‧‧‧Second process gas inlet

10‧‧‧First stranded outflow

11‧‧‧Second stranded outflow

12‧‧‧First infiltration side

13‧‧‧Second infiltration side

14‧‧‧First permeate outlet

15‧‧‧Second permeate outlet

16‧‧‧ Pressure swing adsorption unit

17‧‧‧ Third Process Gas Inlet

18‧‧‧ flushing gas outlet

19‧‧‧Product gas export

20‧‧‧feed line

21‧‧‧Product gas pipeline

22‧‧‧Compressor level

23‧‧‧Pre-cleaning unit

24‧‧‧氦Recycling equipment

25‧‧‧Production line

26‧‧‧First stranded flow line

27‧‧‧First permeate flow line

28‧‧‧First return line

29‧‧‧Second return line

30‧‧‧First exhaust gas pipeline

31‧‧‧Second exhaust gas pipeline

Claims (7)

A method for extracting ruthenium from a ruthenium containing process gas, comprising at least the steps of: a) delivering a ruthenium containing process gas to a compression device (22), wherein the ruthenium containing process gas has a pressure of less than 15 bar, preferably less than 10 bar , b) conveying the process gas discharged from the compression device (22) to the pre-purification unit (23), removing the interference component in the pre-purification unit; c) introducing the process gas of the removed interference component a first membrane separation stage (2) having a first membrane (4) which is more susceptible to penetration by helium than at least one other component contained in the process gas; d) will not penetrate the membrane The first retentate stream of the first membrane (4) is introduced into a second membrane separation stage (3) having a second membrane (5) which is more than the at least one other component contained in the process gas Easily infiltrated by helium; e) separating helium from the first helium permeate stream that has penetrated the first membrane (4) by pressure swing adsorption, and producing a rhodium-containing product stream; and f) will have penetrated the The second cerium-containing permeate stream of the second membrane (5) is returned to the first membrane separation stage (2), and the flushing gas of the pressure swing adsorption device (16) is returned to the first membrane. From stage (2). The method of claim 1, characterized in that temperature swing adsorption or reaction, in particular thermal oxidation, is carried out in the prepurification unit (23). The method of claim 1 or 2, wherein the process gas is a process exhaust gas for manufacturing a manufacturing process (25) for an electronic component and/or a semiconductor component, wherein the interference component to be removed by the pre-purification comprises At least one of the following components: H ₂ , hydrocarbon, H ₂ O, CO ₂ , sulfur compound, decane, phosphine, arsine, halogenated hydrocarbon, fluorinated gas (particularly SF6 or NF3), metal hydride. The method of claim 1 or 2, characterized in that The second retentate stream (30) that does not penetrate the second membrane (5) is used to regenerate the adsorber used in the temperature swing adsorption unit (23). A method according to claim 1 or 2, characterized in that the second retentate stream (30) which does not penetrate the second membrane (5), in particular, expands its work in the case of generating electrical energy. The method of claim 1 or 2, wherein the first permeate stream has a niobium content of 25 vol% or more, and/or the niobium content of the product stream is greater than or equal to 95 vol%, specifically 99 vol% or more. The method of claim 1 or 2, wherein the cerium-containing process gas has a cerium content of more than 0.1 vol%, preferably more than 0.5 vol%.