JP5970860B2 - Hydrogen separation system - Google Patents

Description

  The present invention relates to a hydrogen separation system that separates hydrogen from a fuel gas supplied to a gas engine or the like, and more particularly, to a hydrogen separation system that can separate hydrogen from an original fuel gas with high energy efficiency.

  Conventionally, regarding a gas engine, it is known that problems such as knocking and backfire may occur when the hydrogen concentration in the fuel gas is high. For example, Patent Document 1 discloses knocking in order to avoid the occurrence of knocking. A technique for reducing the hydrogen mixing ratio in the fuel gas when the occurrence of hydrogen is predicted is disclosed.

  On the other hand, as a device for separating and removing hydrogen in a gas, for example, a PSA (Pressure Swing Adsorption) method and a separation membrane method are known. In such a separation method, generally, the pressure and permeation of gas on the supply side are known. The separation performance improves as the pressure difference from the gas pressure on the side (hydrogen enrichment side) increases.

Patent 3618312

  However, when the pressure difference is to be obtained by increasing the pressure of the gas (source fuel gas) on the supply side, more energy is required, as will be described later. Prediction will remain. Moreover, such a problem is not limited to the case where fuel gas is supplied to the gas engine, but may also occur when fuel gas is supplied to other gas utilization means.

  This invention is made | formed in view of the said problem, The objective is to provide the hydrogen separation system which can isolate | separate hydrogen from original fuel gas efficiently.

The hydrogen separation system of the present invention for achieving the above object is as follows:
1. Hydrogen separation means for separating hydrogen from an original fuel gas containing flammable gas other than hydrogen and hydrogen, taking out fuel gas with reduced hydrogen from the primary side and taking out gas enriched with hydrogen from the secondary side;
Decompression means for decompressing the gas on the secondary side;
Gas utilization means for utilizing the fuel gas;
A hydrogen separation system comprising:
A hydrogen separation system that performs hydrogen separation from the original fuel gas while decompressing the secondary side by the decompression means.

2. The system according to 1 above, wherein methane is included as a combustible gas other than hydrogen in the original fuel gas.

3. 3. The system according to 1 or 2 above, further comprising a hydrogen concentration detection means in a gas line on the primary side where hydrogen is reduced.

4). 4. The system according to 3 above, wherein the degree of pressure reduction of the gas by the pressure reducing means is controlled according to the detection result of the hydrogen concentration detecting means.

5. The system according to any one of the above 1 to 4, wherein the hydrogen separation means is a separation membrane.

6). The system according to any one of the above 1 to 5, further comprising a boosting unit that boosts the gas in a supply line that supplies the original fuel gas to the hydrogen separation unit.

7). The system according to any one of the above 1 to 6, wherein the gas utilization means is a gas engine or a burner.

8). 8. The system according to any one of 1 to 7, wherein the hydrogen concentration of the gas with reduced hydrogen is 5 mol% or less.

9. 9. The gas according to any one of the above 1 to 8, wherein the gas enriched with hydrogen is supplied to a separation membrane system for further concentrating hydrogen or another hydrogen separation means of a PSA system. System.

10. The system according to any one of the above 1 to 9, wherein the original fuel gas is an off-gas of a hydrogen PSA device.

  ADVANTAGE OF THE INVENTION According to this invention, the hydrogen separation system which can isolate | separate hydrogen from original fuel gas efficiently can be provided.

It is a figure which shows typically the structure of the hydrogen separation system of 1st Embodiment. It is a figure which shows the example which changed a part of structure of the system of FIG. It is a figure which shows typically the structure of the hydrogen separation system of 2nd Embodiment. It is a figure which shows typically the structure of the hydrogen separation system of 3rd Embodiment. It is a figure which shows typically the structure of the hydrogen separation system by the other example of this invention. It is a figure which shows typically the structure of the hydrogen separation system by the further another example of this invention. It is a figure which shows typically the structure of the hydrogen separation system by another example of this invention.

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

[First Embodiment]
The hydrogen separation system of FIG. 1 includes a hydrogen separator 11 that separates hydrogen from an original fuel gas supplied via a supply line 21, and a gas that uses a fuel gas whose amount of hydrogen has been reduced by the hydrogen separator 11 as fuel. And a utilization device 15.

  The original fuel gas supplied from the supply line 21 is not limited. For example, exhaust gas discharged in a chemical process, coal gas, petroleum refined off-gas, natural gas, reformed gas, or coke oven gas ( COG) can be used. The original fuel gas may be off gas discharged from a hydrogen PSA device (not shown). The supply pressure of the original fuel gas only needs to be equal to or higher than the atmospheric pressure. However, when it is necessary to increase the pressure of the original fuel gas, for example, a booster 19 may be provided in the supply line 21 as shown in FIG. Examples of the booster 19 include a blower and a gas compressor.

  The hydrogen separator 11 is of a separation type in which the separation performance varies depending on the pressure difference between the primary side (raw material supply side) and the secondary side (hydrogen concentration side). For example, a separation membrane type or PSA is used. The system can be used. In these hydrogen separators, in general, the greater the pressure difference, the better the separation performance, and a greater amount of hydrogen will be separated.

  Two lines 22a and 22b are drawn out from the hydrogen separator 11, and the primary side line 22a is a line on the side where hydrogen is separated (that is, the side where fuel gas with reduced hydrogen content is discharged). The secondary side line 22b is a line where hydrogen is concentrated. The primary side line 22a is configured to supply fuel gas to the gas utilization device 15, and the secondary side line 22b is provided with a gas decompression device 13 (details below).

  When the hydrogen separator 11 is a separation membrane type, for example, a separation membrane module using a hollow fiber membrane may be used. In this case, the separation membrane module may be either a so-called bore feed type or a shell feed type. The structure of the gas separation membrane module itself is conventionally known. For example, hundreds to hundreds of thousands of hollow fiber membrane bundles (hollow fiber bundles), a container for accommodating the hollow fiber membrane bundles, and both ends of the hollow fiber bundles You may provide the tube sheet etc. which were formed in the part. In the case of bore feed type, the original fuel gas is fed into the membrane from one opening of each hollow fiber membrane (the inside of the membrane is the primary side), and hydrogen in the original fuel gas selectively permeates through the membrane. To the side (secondary side). Thereby, hydrogen is separated from the original fuel gas, the fuel gas from which hydrogen has been separated is supplied to the gas utilization device 15 via the primary side line 22a, and the gas enriched with hydrogen passes through the secondary side line 22b. Is taken out through.

  As the hollow fiber, one having a small thickness and a small diameter can be used. In this case, even a small apparatus can have a high membrane area and increase the separation efficiency. The hollow fiber is not limited, but may have a film thickness of 10 to 500 μm and an outer diameter of about 50 to 2000 μm. The gas separation membrane may be homogeneous, may be non-uniform such as a composite membrane or an asymmetric membrane, and may be microporous or nonporous. Examples of the gas separation membrane include those formed of a polymer material such as polyimide, polyetherimide, polyamide, polyamideimide, polysulfone, polycarbonate, silicone resin, and cellulose polymer, and a ceramic material such as zeolite. As a gas separation membrane formed of polyimide, for example, an aromatic polyimide hollow fiber separation membrane is preferable, and an aromatic polyimide asymmetric hollow fiber separation membrane is more preferable. Examples of the form of the hollow fiber bundle include a parallel arrangement, a cross arrangement, a woven form, and a spiral form. Moreover, the hollow fiber bundle may be provided with a core tube at a substantially central portion, or a film may be wound around the outer peripheral portion of the hollow fiber bundle. Further, the hollow fiber bundle may have a cylindrical shape, a flat plate shape, a prismatic shape, or the like. Further, the hollow fiber bundle is not limited to a straight form, and may be a form bent in a U shape, a form wound in a spiral form, or the like.

  The gas utilization device 15 may be any device as long as it uses hydrocarbon fuel gas, and examples thereof include a gas engine and a burner. For example, the gas engine may be used for power generation.

  The decompression device 13 may be any device as long as it has a function of decompressing the gas on the secondary side. Specifically, a blower, an ejector, a vacuum pump, or the like may be used. The decompression performance is desirably such that the secondary side gas is decompressed by about 0.5 to 1 atm, preferably 0.6 to 0.95 atm, and more preferably about 0.7 to 0.9 atm. . The decompression device 13 may be any one that can be simply switched on / off, one that can change the decompression level in a plurality of stages, and one that can set an arbitrary decompression level steplessly.

  The operation of the hydrogen separation system of the present embodiment configured as described above will be described below.

  In this hydrogen separation system, hydrogen separation is performed while supplying the original fuel gas to the hydrogen separation device 11 via the supply line 21 and driving the decompression device 13 to decompress the secondary side. As an example, the supply of the original fuel gas may be started after a predetermined time has elapsed after the decompression device 13 is started and the secondary side line 22b is sufficiently decompressed.

  By depressurizing the secondary side by the decompression device 13, a pressure difference between the supply side and the secondary side of the hydrogen separation device 11 is generated, whereby hydrogen separation is started, and fuel gas is taken out from the primary side line 22a. The concentrated hydrogen gas is taken out from the secondary line 22b. The hydrogen concentration of the fuel gas can be changed as appropriate, but may be preferably 10 mol% or less, more preferably 5 mol% or less, and even more preferably 2 mol% or less.

  If the decompression device 13 is not provided, it is necessary to increase the pressure of the entire original fuel gas and supply it to the hydrogen separation device 11. In this case, although the hydrogen separation in the hydrogen separation device 11 is performed without any problem, from the same device 11 The extracted primary fuel gas has a higher pressure than necessary, and in some cases, a separate process for lowering the pressure of the primary fuel gas may be required. On the other hand, according to the configuration of the present embodiment, the pressure difference of the hydrogen separator is ensured by reducing the pressure on the secondary side with the pressure reducing device 13 (in the configuration of FIG. 19 may be used together), it is not necessary to increase the pressure of the original fuel gas excessively, and wasteful energy consumption can be suppressed and hydrogen separation can be performed efficiently.

  In addition, the configuration of the present embodiment is particularly suitable when the original fuel gas having a relatively low pressure is used because hydrogen separation can be performed without increasing the pressure of the original fuel gas.

[Second Embodiment]
FIG. 3 is a diagram schematically illustrating the configuration of the hydrogen separation system according to the second embodiment. In FIG. 3, the same reference numerals as those in FIGS. 1 and 2 are given to the structural portions having the same functions as those in the above embodiment.

  The system in FIG. 3 includes a hydrogen separator 11, a decompressor 13, and a gas utilization device 15 as in the above embodiment, and further a hydrogen concentration sensor for detecting the hydrogen concentration in the fuel gas in the primary line 22 a. 16 is provided. The hydrogen concentration sensor 16 may be of any type as long as it can detect the hydrogen concentration (hydrogen amount) in the gas.

  The system of FIG. 3 includes a controller 30, which is configured to adjust the operation of the decompression device 13 based on the detection result by the hydrogen concentration sensor 16. That is, the controller 30 determines whether or not the hydrogen concentration in the fuel gas exceeds a predetermined upper limit value based on the detection result of the hydrogen concentration sensor 16. Control to increase the degree of decompression by increasing the output of 13 is performed. As a result, the degree of decompression on the secondary side increases (the pressure decreases) and the pressure difference of the hydrogen separator 11 increases, and as a result, more hydrogen is separated from the original fuel gas. Thereby, the amount of hydrogen in the fuel gas taken out from the primary side can be reduced.

  The trigger for terminating the above operation is not particularly limited, and for example, the decompression device 13 may be configured to return to the normal operation after a predetermined time has elapsed. Alternatively, the decompression device 13 may be configured to return to normal operation when it is determined that the hydrogen concentration in the fuel gas has fallen to a predetermined range using the detection result of the hydrogen concentration sensor 16.

  According to the configuration of the present embodiment, it is possible to detect the hydrogen concentration in the combustion gas by the hydrogen concentration sensor 16 and adjust the degree of decompression by the decompression device 13 based on the detection result. Therefore, in addition to the operational effects of the first embodiment, the hydrogen concentration in the fuel gas supplied to the gas utilization device 15 can be controlled more accurately.

[Third Embodiment]
FIG. 4 is a diagram schematically illustrating the configuration of the hydrogen separation system according to the third embodiment. In FIG. 4, the same reference numerals as those in FIGS.

  The system of FIG. 4 is the same as the configuration of FIG. 3 above in that it includes a hydrogen separator 11, a decompressor 13, a gas utilization device 15, a hydrogen concentration sensor 16, and the like. However, the additional line 22c is connected to the upstream side of the decompression device 13 of the secondary side line 22b, and the secondary side line 22b is in a state of bifurcating in the middle. The additional line 22c is connected again to the secondary side line 22b on the downstream side of the decompression device 13, and has a loop configuration. The additional line 22 c is provided with an adjustment valve 17 that can adjust opening and closing under the control of the controller 30. The adjustment valve 17 may switch the opening / closing of the additional line 22c, or may switch the opening degree of the flow path in stages. In the system of FIG. 4 configured as described above, the gas flow rate can be adjusted by a so-called spillback method.

  As an example, the pressure in the secondary side line 22b can be changed by adjusting the opening and closing of the adjustment valve 17 while the operation of the decompression device 13 is kept constant. That is, during normal operation, the decompression device 13 is continuously operated at a slightly higher output, while the adjustment valve 17 is opened. Thereby, the pressure reduction degree of the secondary side line 22b is relieved, and becomes a predetermined pressure reduction degree.

  Next, when the controller 30 determines based on the detection result of the hydrogen concentration sensor 16 that the hydrogen concentration in the fuel gas exceeds a predetermined upper limit value, the controller 30 performs control to close the adjustment valve 17. As a result, the additional line 22c is closed, and the degree of decompression in the secondary side line 22b increases, so the amount of hydrogen separated by the hydrogen separator 11 increases, and as a result, the fuel taken out from the primary side The amount of hydrogen in the gas is further reduced.

  The trigger for ending the operation is not particularly limited, and as described above, the adjustment valve 17 may return to the open state after a certain time has elapsed, or based on the detection result of the hydrogen concentration sensor 16. The controller 30 may be configured to return the adjustment valve 17 to the open state.

  Depending on the system, it is assumed that it is difficult or inefficient to finely control the operation of the decompression device 13, but according to the present embodiment, the decompression device 13 is operated continuously. By driving the adjustment valve 17, the degree of decompression of the secondary line 22b can be changed.

  In the configuration of FIG. 4, not only one of the adjusting valve 17 and the pressure reducing device 13 but both of them may be controlled by the controller 30.

  As mentioned above, although several embodiment was mentioned as an example about this invention, this invention is not limited above, Various changes are possible. For example, FIG. 5A shows a configuration in which a separation membrane module 11A is used as a hydrogen separator in the configuration of FIG. Of course, the separation membrane module can also be used in the systems shown in FIGS.

  FIG. 5B is basically similar to the configuration of FIGS. 4 and 5A, but differs in that a booster 19 is provided in the supply line 21 connected upstream of the separation membrane module 11A. As described above, the booster 19 as shown in FIG. 2 can be used in the systems as shown in FIGS. 3, 4, and 5A.

  FIG. 6 is an example in which a hydrogen separator 11-2 is further added to the secondary line 22b of the system of FIG. As described above, the gas in which the hydrogen is concentrated after passing through the first hydrogen separator 11-1 may be further supplied to another hydrogen separator 11-2. As the hydrogen separator 11-2, a separation membrane type or a PSA type may be used as described above. Also, the two hydrogen separators 11-1 and 11-2 may be the same method, the first may be the PSA method and the second may be the separation membrane method, or vice versa. The eye may be a separation membrane type and the second may be a PSA type.

  4, 5 </ b> A, and 5 </ b> B exemplify the spillback configuration, the present invention is not necessarily limited to this. For example, the end of the additional line 22 c is connected to a nitrogen supply source (not shown). It is good also as a structure which is connected and nitrogen is supplied through this line 22c. However, according to the configuration shown in FIGS. 4, 5A, and 5B, since the decrease in the hydrogen gas concentration in the secondary line 22b can be prevented, for example, as shown in FIG. Suitable for use in 11-2.

DESCRIPTION OF SYMBOLS 11, 11-1, 11-2 Hydrogen separation apparatus 11A Separation membrane module 13 Decompression apparatus 15 Gas utilization apparatus 16 Hydrogen concentration sensor 17 Adjustment valve 19 Booster 21 Supply line 22a Primary side line 22b Secondary side line 22c Additional line 30 Controller

Claims (7)

Hydrogen separation means for separating hydrogen from an original fuel gas containing flammable gas other than hydrogen and hydrogen, taking out fuel gas with reduced hydrogen from the primary side and taking out gas enriched with hydrogen from the secondary side;
Decompression means for decompressing the gas on the secondary side;
Gas utilization means that is a gas engine utilized as the fuel gas;
A hydrogen concentration detection means provided in a primary gas line where hydrogen is reduced;
A hydrogen separation system comprising:
Performing hydrogen separation from the original fuel gas while decompressing the secondary side by the decompression means ; and
A hydrogen separation system configured to control the degree of gas decompression by the decompression means in accordance with the detection result of the hydrogen concentration detection means .   The system of claim 1, comprising methane as a combustible gas other than hydrogen in the source fuel gas. The system according to claim 1 or 2 , wherein the hydrogen separation means is a separation membrane. The system according to any one of claims 1 to 3 , further comprising a boosting unit configured to boost the gas in a supply line that supplies the original fuel gas to the hydrogen separation unit. The system according to any one of claims 1 to 4 , wherein the hydrogen concentration of the gas with reduced hydrogen is 5 mol% or less. The gas hydrogen is concentrated is configured to be supplied to another of the hydrogen separation means the separation membrane system or PSA system for further concentration of hydrogen, in any one of claims 1 to 5 The described system. The original fuel gas is off-gas of hydrogen PSA device, according to any one of claims 1 to 6 System.

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