JPS60176901A - Method for concentrating and purifying hydrogen, etc. in mixed gas containing at least hydrogen by using adsorption - Google Patents

Abstract

PURPOSE:To enable the concentration and purification of hydrogen in a hydrogen-containing mixed gas in high efficiency, by using a plurality of adsorption beds, filling an adsorbent having selective adsorptivity to at least one kind of the impurity component in the mixed gas in each bed, and repeating the adsorption, evacuation, desorption and pressurization. CONSTITUTION:Hydrogen in a hydrogen-containing mixed gas is concentrated and purified by adsorption method using three or more adsorption beds. Each bed is filled with an adsorbent having selective adsorptivity to one or more impurity components in the mixed gas, and is furnished with an inlet and an outlet. The adsorption process and the adsorption and pressurization process are repeated by changing the direction of the flow periodically to concentrate and purify the hydrogen in the hydrogen-containing mixed gas.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention utilizes a pressure-3wi adsorption method.
(ng-Atlsorption: PSA) to increase the concentration of hydrogen gas in a mixed gas containing at least hydrogen gas in U1 gas of petrochemical plants, reduction furnaces, annealing furnaces, etc., or to simultaneously increase the concentration of hydrogen gas in a mixed gas other than hydrogen gas. This invention relates to inexpensive equipment that can simultaneously recover adsorbed gases and a method for recovering them at low operating costs.

The PSA method involves repeating the process of selectively adsorbing gas onto an adsorbent at high pressure and desorbing it at low pressure.
This is a method of shrinking and separating. When a mixture of two or more gases is passed through a bed of adsorbent, the adsorbent has selective adsorption properties for the components contained in the gas mixture. Therefore, the impurity components in the mixed gas can be adsorbed and removed by the PSA method using a specific adsorbent, and the mixed gas can be separated and concentrated.

A method of adsorbing and separating hydrogen gas from a mixed gas using a pressure fluctuation adsorption separation method is well known and has been practiced for a long time. For example, Esso's Special Publication No. 38-25969 and Special Publication No. 39-208, etc. +/c Union Carbide Company's Special Publication No. 38-23928, Special Publication No. 43-284
, and the Special Publication No. 55-12295, etc.,
In both cases, high adsorption pressure is used for adsorption separation and recovery, which consumes a lot of power energy to compress the mixed gas, and requires complicated processes to recover that energy, making the equipment and operations complicated. There are problems such as: The purpose of the present invention is to improve such drawbacks and provide a method for recovering hydrogen gas or a mixture of two gases, hydrogen gas and pond gas, at low cost by simplifying the operation of the device and reducing the compression power of the mixed gas. It's about doing.

Exhaust gases containing hydrogen from petrochemical, reduction furnaces, annealing furnaces, etc. are currently disposed of in the atmosphere or burned. Although water cable waste is recovered from this exhaust gas and contributes to resource and energy conservation, this practice is still very limited. Therefore, the present inventors raised the temperature of hydrogen or a mixed gas of hydrogen and one component other than hydrogen, removed impurity components, and used it as a raw material gas for petrochemicals, reduction furnaces, annealing furnaces, etc. As a result of intensive study of the PSA method, we discovered the following.

It is common knowledge to those skilled in the art to separate hydrogen from a hydrogen-containing gas mixture by selecting an appropriate adsorbent. Therefore, hydrogen, carbon dioxide gas,
There are patent applications and patents for separating oxygen, nitrogen, etc.

However, all of these generally require the use of multiple adsorption beds [
The steps of adsorption, depressurization, desorption, and pressurization are also repeated in the above-mentioned adsorption bed, which repeats the basic process of "adsorption - depressurization, one adhesion, one pressurization". Pressurization is generally accomplished by a gas compressor using electrical energy. The amount of electrical energy used for pressurization is proportional to the pressure of the adsorption bed. Increasing the pressure of the adsorption bed increases separation efficiency in mixed gases, but also increases electricity costs.

Also, lowering the adsorption bed pressure can save electrical energy but increase separation efficiency. Therefore, in general, hydrogen or/or a mixed gas of hydrogen and one component other than hydrogen is separated from a mixed gas containing hydrogen at a high pressure (9 kg/,:
The process is carried out at m2G or more, and efforts are being made to recover energy by using various techniques for the gas in the adsorption bed after adsorption. In other words, we are focusing on how to prevent the loss of energy once pressurized, but the inventors of the present invention have worked hard to find out how to efficiently separate and concentrate by reducing the pressurizing energy. The method of reducing the total energy during pressurization as disclosed in Japanese Patent Publication No. 53-99091, or even at the start of the adsorption process, starts the adsorption process below the adsorption pressure and increases the adsorption pressure during the adsorption process to mix. This method was discovered after extensive research on the steps in the PSA method, based on the method proposed in JP-A-Sho (Japanese Patent Application Laid-Open No. 2002-120000). This method removes impurity components from a mixed gas containing at least hydrogen to produce hydrogen or The present invention provides a method for inexpensively producing a mixed gas containing hydrogen and one component other than hydrogen.

In the first invention, at least three beds are used when concentrating hydrogen or/a mixed gas of extracted hydrogen and one component other than hydrogen from a mixed gas containing at least hydrogen, using an adsorption method. is filled with an adsorbent that selectively adsorbs at least one of the impurity components in the mixed gas, each bed has an inlet end and an outlet end, and the method is (1) Equal pressure pressurization] A raw material gas is introduced into the bed where the process has been completed, and impurity components are adsorbed on the adsorbent while pressurizing to reach the adsorption pressure at or near the end point 1 of the adsorption process or during the adsorption process. Alternatively, /1 is adsorption (I+ step) to obtain a mixed gas of hydrogen and one component other than hydrogen (hereinafter referred to as product gas), (111 adsorption (II) pressurization with the bed after step IIl and the following product gas). A pressure equalization step where the pressure of both methods is approximately averaged by connecting the bed where step (vI) has been completed, and (iii+) connecting the bed where the pressure equalization and pressure relief step has been completed with the bed where the exhaust step has been completed. (1v) A depressurization process in which all residual gas in the bed is released by using the decompressed gas from the former floor as exhaust gas for the latter bed and maintaining it near atmospheric pressure. Exhaust process (VJ) Exhaust purge process in which exhaust is performed while using the entire gas during the depressurization process on the floor after the pressure equalization process as purging gas (■1) Product gas is removed from the floor where the exhaust purge process (Vlil) The bed where the pressurization process with the product gas has finished and the bed where the adsorption process has finished are connected, and the gas released from the latter bed is connected. Adsorption that introduces into all the former floors and brings the former floor to zero pressure■
) A pressure equalization step, and the above operation is repeated by changing the flow periodically.

The adsorbent used in the present invention is silica gel for removing water from the bottom of the adsorption bed, activated carbon zeolite thread material (for example, A%X, K type molecular thief, natural or modified Alternatively, use synthetic mornanite, etc., in three or more layers, or activated carbon or zeolite material whose particle size is much smaller than the entire lower layer.

The second invention is to connect the step 8 of the first invention (one pile, that is, the bed where the adsorption (Il step has been completed) and the bed where the following pressurization step (1v) using the product gas has been completed, to obtain both methods. Instead of a pressure equalization step that approximately equalizes the pressure, the adsorption fIl
Pressure process (v
Connect the bed where step 1) has been completed to approximately equalize the pressure of both beds, and at the same time release a portion of the gas in the bed from the feed gas inlet end at the bottom of the adsorption bed where step 11 has been completed. This invention differs from the first invention in that an equal pressure discharge step is carried out.

The first invention and the second invention are the same with respect to the (H,' (iiil, (1v), (v), (vl), and (vll) steps).

The steps of the present invention will be explained in detail below.

(1) Adsorption process The mixed gas is introduced in parallel flow direction from the raw material gas inlet valve at the lower inlet end of the adsorption bed, and the product gas is adsorbed while gradually increasing the pressure from the total pressure equalization pressure of the adsorption bed. In this process, the pressure of the adsorption bed is lower than the pressure of the product gas in the buffer tank at the beginning of this adsorption process. Prevent backflow using a prevention valve.

Adsorption (Tl
After the adsorption (I+ step of the adsorption bed is completed, the introduction of the mixed gas is stopped, and the pressure step (vl) using the bed where the adsorption (II step has ended and the product gas) is completed. A pressure equalization process in which the pressures of both methods are almost averaged by connecting the inner bed.In this case, the pressure of the inner bed is almost averaged, and at the same time the adsorption from the raw material gas inlet end to the inlet end side of the lower part of the adsorption bed The gas in the gap between the agents and the gas desorbed from the adsorbent may be released.When the pressure in the bed is averaged, the release valve and the pressure equalization valve are closed to complete the pressure equalization.

1ii) Pressure equalization (tiy: a gas exhaust bar that connects the adsorption bed after the completion of the extraction process with the bed after exhaustion and releases it under reduced pressure)
The depressurization process (1) releases the residual gas in the bed at a temperature close to the total atmospheric pressure (C) in the bed. (V) The exhaust purge process is a process in which the gas in the bed is preferably exhausted in a countercurrent direction using a decompression exhaust device (vacuum pump, ejector, blower, etc.). Depressurization - [In the process of depressurization, the emitted gas is passed in all countercurrent directions for adsorption?' Pressure is applied in the direction of
Pressure] A process in which the adsorption bed is pressurized with the optimum amount of product gas using a product gas pressurization valve to prevent disturbance of the adsorption bed during the process.

(viil pressure equalization (pressure) step, a step in which the adsorption bed after the adsorption (I) step is connected to the bed after the product gas has been removed, and the residual gas in the former bed is recovered into the latter bed. In this step, the pressure is averaged (equalized) in parallel flow from the raw material gas inlet end of the adsorption bed.After this step is completed, the process shifts to the adsorption (I) step (1) and is continuously operated.

In this example, 7 processes were carried out in 9 steps as shown in the flow sheet shown in the figure and 3 adsorption beds and the process operator shown in Table 1.

The present invention will be described in detail below based on a typical example of the present invention, which is a method for removing impurity components in reduction furnace exhaust gas and completely separating and recovering a mixed gas of hydrogen gas and nitrogen gas. The method is not limited to these specific examples.

The figure is a flow sheet for removing impurity components (components that are easily adsorbed) from reduction furnace exhaust gas using the adsorption method, and separating and concentrating hydrogen, which is a component that is difficult to adsorb, and one component other than hydrogen (nitrogen).

Adsorption beds A, B, and C contain adsorbents that selectively adsorb impurity components (easily adsorbed components). Adsorption beds A, B,
C, is decompressed using a decompression exhaust device k 300 To
rr or less preferably 100 Torr ~ 50 Tot
Valve (19), (2o), (211
'if open and activate. Now, the entire product gas is introduced into the adsorption bed A by opening the valve (10) to increase the pressure from the vacuum state. All except valve (1o) are closed. When the product gas capacity E f reaches the equalized daily pressure end pressure, the valve (1o) closes and the adsorption pressure is 0.05 kg.
/Cm2G to 3 kg/cs 2G, preferably 0
．． Valves (1) and (2) are opened at an adsorption pressure f1 of 1 kg/Cln2G to 1 kg/Cm2G, and impurity components in the raw material gas are selectively adsorbed by the adsorbent.
Hydrogen, which is an adsorbed component, is absorbed by the adsorption bed Iij D end valve (2
) and is introduced into the product tank through the backflow prevention valve CV. When only hydrogen is concentrated and recovered, the adsorption step can be completed before nitrogen, the second poorly adsorbed component, breaks through (detected).When recovering a mixed gas, the adsorption step is continued and the second difficultly adsorbed component When (g element) breaks through,
The adsorption time or the product gas removal air may be set so that the adsorption process ends when the desired concentration of the mixed gas is reached.

After the adsorption process is completed, the valves (1) (21) are closed, and the valves (7) (19) for pressure equalization are fully opened and the product gas is connected to the bed (B) after pressurization, and the inside of the adsorption bed A is closed. At the same time, the residual gas is removed in a trench where the pressure of the adsorption bed B is averaged, and at the same time, the adsorption zone of impurity components during adsorption is removed from the adsorption bed outlet end V (the valve (10) on the raw material gas end side so that it does not move). After the pressure is released, the impurity components are released to the atmosphere. When the adsorption beds A and B are averaged, the valve (7) is closed, and the valve (13) is fully opened to adsorb the remaining gas in the Hiratsuka adsorption bed <A,). Use it as the exhaust purge gas for bed C and the burn gas for bed C that has completed the exhaust process.At this time, if there is a large amount of adsorbed liquid for impurity components, you may continue to release the pressure a little from the valve (10). invention).

This does not necessarily have to be done. Adsorption bed A in the depressurization process
When the pressure becomes close to atmospheric pressure, the valve (10) (J3) is closed, and a high-pressure exhaust device is used to exhaust the gas in the gaps between the adsorbents in the adsorption bed. From 50 Torr!'C1r
Do LIEJ'Jl'ki. After the evacuation is completed, evacuation is performed while evacuation is being carried out in order to desorb impurity components from the voids between the adsorbent particles by the gas released from the evacuation.

At this time, the pressure of the exhaust bar 7 is set to 200 Torr or less, preferably 150 Torr or less. After the exhaust burn is completed, the valve (19) is closed and the valve (16) is opened to pressurize the product gas. At this time, in order to adjust the product pressure flow sewing, the valve (221) is used to slowly discharge the remaining impurities that could not be completely removed by the exhaust part to the raw material gas inlet end. Do the product gas sword n
After the completion of pressure 7, the adsorption process is connected to the end bed C, and after the completion of the adsorption process, the adsorption bed Af force [1 pressure use

By repeating the above operation j-th time in each adsorption bed, impurity components can be continuously adsorbed onto the adsorbent, and hydrogen or hydrogen and nitrogen can be separated and concentrated.

Example 1 In order to further specifically explain the present invention, reduction furnace exhaust gas (H2 = 52% N2 - 42% C0 = 5% CO2 -
An attempt was made to concentrate and purify 1% NH4-300pyym).

As described above, the M-manufacturing process was carried out based on the purification cycle of "adsorption-equalization pressure relief-depressurization-exhaust-exhaust bargie product gas pressurization-equalization (adsorption 1)".

Activated alumina 64 to 9% activated carbon pellets 115ky
Steel adsorption bed (24 x 4.3 m) packed with 240 kg of zeolite pellets and evacuated to 100 T
After maintaining the exhaust gas at a linear velocity of 2. Ocm/se
Concentration and purification were carried out by introducing the solution from the bottom of the bed at step c.

105m3 of product gas for 200m3 of supplied gas
Recovered. At this time, the concentration of hydrogen gas was 75%, the nitrogen gas was 25%, and the recovery rate of hydrogen gas was about 76%. Pressure - Depressurization - Exhaust - Exhaust bargie Product gas pressurization - Equal pressure (Adsorption (11)
It was carried out based on the refining cycle of ``.

64 kg of activated alumina, 5 kg of activated carbon%
Steel filled with zeolite% pellets 240kj7-i,
Adsorption bed of a<24B
52%, A'2=42%, C0=4%, 002=2%
Purification of NJ-132000ppm) and a-rice production were carried out.

98m3 of product gas for the supplied gas amount of 194m”
Recovered. At this time, the ratio of the mixed gas of hydrogen and nitrogen was 80% hydrogen gas and 20% nitrogen gas, and the hydrogen gas recovery rate was about 77.7%.

An example of cycle structure (first invention) in the case of a three-bed type is as follows.

An example of the cycle configuration of another aspect (the second invention is as shown below).

In the present invention, an embodiment using three beds has been described, but four or more beds may be used.

[Brief explanation of the drawing]

The figure is a flow sheet of a preferred apparatus for carrying out the entire method of the invention. Patent applicant Osaka Sanso Kogyo Shishiki Co., Ltd. (4 others) Procedures Amendment 1. Display of the incident 1982 Patent Application No. 3000. ! S No. 2, Name of the invention, Person making the amendment 4, Agent 5 Column 6, [Detailed description of the invention] of the subject specification to be corrected, Contents of the amendment (1) Page 10, line 16 of the specification Correct all 14 lines to ``Use the one.'' (2) The description shall be amended as follows. Page Line Before correction After correction゛6 11 Energy 7 14 Efficiency increases Efficiency decreases. 7 19 Energy Todo Energy 11 19 (Release process (Release) process 1411-12
Pulp (10) Pulp (16) 4 12 4 14 15 9 (7) (9) (7) 15 16 Averaging degree Averaging back body Top

Claims (1)

[Scope of Claims] (1) Hydrogen or/or a mixed gas containing at least hydrogen
-! When concentrating a gas mixture of hydrogen and one component other than hydrogen using an adsorption method, at least three beds are used, and each bed has a selective adsorption property for at least one of the impurity components in the gas mixture. Each bed has an inlet end and an outlet end, and the method is (1) introducing the raw material gas into the bed where the pressure equalization and pressurization process has been completed;
At or near the end point of the adsorption process or during the adsorption process, impurity components are adsorbed on the adsorbent while applying Calo pressure to reach the adsorption pressure. a pressure equalization step to approximately equalize the pressure of adsorption (Step II) to obtain a mixed gas (hereinafter referred to as product gas);
fiin The bed where the pressure equalization process has been completed is connected to the floor where the exhaust process has been completed, and the reduced pressure gas from the former bed is used as the exhaust purge gas for the latter bed, and the residual gas in the bed is released by maintaining the pressure near atmospheric pressure. OV) Exhaust process that uses a full in-bed depressurization exhaust system to depressurize the exhaust, (V) Exhaust while performing exhaust while using the gas during the depressurization process of the bed that has finished the pressure equalization process as a part gas. (■1) A product gas pressurization process in which the product gas is passed through the bed where the exhaust purge process has finished and the bed is pressurized; The process consists of a pressure equalization process in which all the beds that have completed the adsorption process are connected, and the gas released from the latter bed is introduced into the former bed to pressurize the former bed, and the flow is periodically controlled. A concentration method characterized by repeating the above operation with different changes. (2) Hydrogen or/- from a mixed gas containing at least hydrogen
Or, when concentrating a mixed gas of hydrogen and one component other than hydrogen using an adsorption method, at least three beds are used, and each bed has selective adsorption properties for at least one impurity component in the mixed gas. Each bed has an inlet end and an outlet end, and the method is (1) introducing a raw material gas into the bed where the pressure equalization and pressurization process has been completed;
At or near the end point of the adsorption process or during the adsorption process, pressurization is applied to reach the adsorption pressure, and impurity components are adsorbed onto the adsorbent to form hydrogen or/or hydrogen and one component other than hydrogen. Adsorption (I) to obtain a mixed gas (hereinafter referred to as product gas)
+ step, ((1) Adsorption (II step) is connected to the bed where the following product gas pressurization step (V
(iii) a pressure equalization step in which a part of the gas in the bed is released from the raw material gas inlet end at the bottom of the adsorption bed after the Il step;
The bed where the pressure equalization and depressurization process has been completed is connected to the bed where the exhaust process has been completed, and all the depressurized gas from the former bed is used as exhaust purge gas for the latter bed, and the remaining gas in the bed is removed by maintaining it at near atmospheric pressure. (Vl An exhaust process in which the inside of the bed is depressurized and evacuated using a decompression exhaust device; (Vl An exhaust process in which the gas during the depressurization process of the bed after the pressure equalization process is used as burn gas while being exhausted) Burn process, (Vllll Product gas pressurization (Vlll) Product gas pressurization (Vllll) Product gas pressurization (Vllll) Product gas pressurization (Vllll) Product gas pressurization (Vlll) Adsorption Q is in communication with the bed where the adsorption process has been completed, and the gas released from the latter bed is introduced into the former bed to pressurize the former bed.
A concentration method characterized by comprising: a TI pressure equalization step; and the above operations are repeated by periodically changing the flow.