JPH03224613A - Gas separator - Google Patents

Abstract

PURPOSE:To retain the product gas returned to an adsorption vessel from a product tank in the adsorption vessel for a long period and to obtain the corresponding improvement of adsorption efficiency by providing returning flow valves which are opened when the adsorption vessel is pressurized and return the product gas in the product tank through plural pipings into the adsorption vessel through plural position of the adsorption vessel, to plural pipings. CONSTITUTION:Plural pipings are provided which connect the adsorption vessels 1, 2 with the product tank 20, and the returning flow valves 8, 9, 18, 19 are provided in plural pipings which are opened when the adsorption vessels 1, 2 are pressurized and return the product gas in the product tank 20 through plural pipings into the adsorption vessels 1, 2 through plural positions of the adsorption vessels 1, 2. By this method, the product gas in the product tank 20 is simultaneously returned to the adsorption vessels 1, 2 through plural pipings, and the product gas is supplied into all over the inner area of the adsorption vessels 1, 2 so that the passing time of gas in the adsorption vessels 1, 2 is elongated and the product gas of high purity is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a gas separation device, and in particular a PSA type (Pre
The present invention relates to a gas separation device suitable for use as a nitrogen generation device or an oxygen generation device, for example.

Conventional technology In general, a PSA gas separation device uses an adsorbent made of molecular sieve carbon to separate air into nitrogen and oxygen.
Either one is taken out and used as a product gas.

For this reason, for example, in a PSA nitrogen generator, there is an adsorption step in which compressed air is introduced into an adsorption tank filled with an adsorbent to apply gastric pressure, and a desorption step in which the inside of the adsorption tank is opened to the atmosphere or the pressure is reduced using a vacuum pump. In the adsorption process, the adsorbent in the adsorption tank adsorbs oxygen molecules and extracts nitrogen to the outside, while in the desorption process, the adsorbed oxygen is desorbed and prepared for the next adsorption process. . Since the product gas, nitrogen, is extracted by increasing the pressure inside the adsorption tank,
The nitrogen gas generated is intermittent and the pressure changes are large. For this reason, when nitrogen gas is used continuously at a constant pressure, a product tank is provided on the extraction side and the nitrogen gas is stored in the product tank.

In addition, in conventional equipment, after the product gas generated in the adsorption tank is taken out into the product tank, the gas remaining in the adsorption tank is supplied to another adsorption tank to equalize the pressure and produce product gas of higher purity. I am trying to generate it. However, as the demand for nitrogen gas increases, it is desired to be able to efficiently generate nitrogen gas of even higher purity.

Problems to be Solved by the Invention An example of a device for solving the above problems is the Utility Model Application Publication No. 1-77
There is one described in No. 828.

The apparatus disclosed in this publication is configured to reflux the product gas that has been pressure-accumulated in the reflux tank from the upper part (downstream side) of the adsorption tank to generate high-purity product gas. However, even in this device, the product gas is only refluxed from the top of the adsorption tank, so the product gas is only supplied near the top of the adsorption tank.
Moreover, since the compressed air from the compressor is supplied from the lower part of the adsorption tank, it is not possible to supply the product gas to the entire interior of the adsorption tank. Therefore, in the above device, even if the product gas is refluxed into the adsorption tank, the refluxed gas is taken out as it is when taking out the product gas from the adsorption tank, so a sufficient reflux effect cannot be obtained and as a result, high purity The problem was that it was not possible to efficiently generate product gas.

Therefore, an object of the present invention is to provide a gas separation device that solves the above problems.

Means for Solving the Problems The present invention provides the above-mentioned gas separation apparatus, in which a plurality of pipes are provided to connect the product tank and the adsorption tank, and when the adsorption tank is pressurized, the valve is opened and the product tank is connected via the plurality of pipes. The plurality of pipes are provided with flow valves for circulating product gas back into the adsorption tank from a plurality of locations in the adsorption tank.

By simultaneously refluxing the product gas in the product tank to the adsorption tank through multiple pipes, the product gas is supplied to the entire area inside the adsorption tank, and the passage time of the refluxed gas in the adsorption tank is lengthened, resulting in higher purity. Can produce product gas.

Embodiment FIG. 1 is a schematic diagram of a nitrogen generator as a first embodiment of the gas separation apparatus according to the present invention.

In Figure 1, 1 and 2 are the first and second adsorption tanks, and each adsorption tank 1
, 2 are filled with molecular sieves IA and 2A, respectively.

3 is a compressor serving as a compressed air supply source, and the compressed air from the compressor 3 is stored in a tank 3a, and is sent to a refrigeration dryer 4. The air is alternately supplied to the adsorption tank 1.2 through the piping 6.7, and for this reason, air supply valves 8 and 9 each consisting of a solenoid valve t and t are installed in the middle of the piping 6.7. is provided.

Reference numeral 28 denotes a reflux pipe, one end of which is connected to a product tank 20, which will be described later, and the other end connected to the pipe 7. A check valve 29 is disposed in this reflux pipe 28.
prevents compressed air from the compressor 3 from being supplied to the product tank 20.

10.11 is a pipe for discharging gas from the adsorption tank 1.2 during the serving, and is connected to a silencer 12 for reducing exhaust noise. Gas exhaust valves 13 and 14 are provided in the middle of the pipes 10 and 11, respectively, which are electromagnetic valves that alternately exhaust the desorbed exhaust gas in the adsorption tank 1.2 every half cycle.

Reference numerals 15 and 16 refer to take-out pipes for taking out nitrogen as product gas from adsorption tanks 1 and 2, and 17 refer to take-out pipes connected to each pipe i5 and 16. In the middle of pipes 15 and 16, there are pipes that will be described later for half a cycle. Take-out valves 18 and 19 are provided, respectively, consisting of electromagnetic valves that open alternately under the control of.

Further, the extraction pipe 17 is connected to a product tank 20.

21 is a pipe communicating between adsorption tanks 1 and 2, 22 is a pipe 21
The pressure equalizing valve 22 is a pressure equalizing valve consisting of a solenoid valve installed in the middle of the adsorption tank 1. The pressure equalizing valve 22 opens for a predetermined short time at the end of a half cycle by the adsorption tank 1.2, and equalizes the pressure between the adsorption tanks 1 and 2. do.

23 is a take-out pipe connected to the product tank 20, and a take-out valve 24 made of a solenoid valve is provided in the middle of the take-out pipe.

25 is a concentration meter, and a branch pipe 2 branches from the take-out pipe 23.
6. Further, an oxygen sensor is used in the concentration meter 25, and the concentration meter 25 measures the oxygen concentration of the gas taken out from the product tank 20 via the takeout pipe 23.

That is, the concentration meter 25 monitors the oxygen concentration contained in the nitrogen gas taken out from the product tank 20, and outputs a signal with a current value proportional to the oxygen concentration. That is, when the nitrogen concentration of the gas accumulated in the product tank 20 decreases, the oxygen concentration inevitably increases.
It can be detected that the nitrogen concentration in the tank has become low. or,
The oxygen concentration measurement signal from the concentration meter 25 is input to a control circuit 27, which will be described later.

The oxygen sensor used in the concentration meter 25 is a magnetic oxygen sensor that utilizes the paramagnetism of oxygen molecules.When oxygen enters the electrolyte through a permeable membrane, a redox reaction occurs at the electrodes, causing a current to flow. Electromagnetic oxygen sensors are used, and zirconia oxygen sensors are used that utilize the fact that electrodes are provided on the inner and outer surfaces of zirconia magnetism and electromotive force is generated depending on the oxygen concentration.

The control circuit 27 is a valve control means constituted by, for example, a microcomputer, and controls the air supply valves 8.9, gas discharge valves 13, 14, etc. based on a predetermined program.
, the opening/closing control of the extraction valves 18 and 19, the pressure equalization valve 22, and the extraction valve 24.

Each electromagnetic valve, which is controlled to open and close by the Il control circuit 27, opens when it is energized by the supply of a valve opening signal, and closes by spring force when it is not energized.

Next, the operation of the nitrogen generator configured as described above will be explained.

First, the basic operation of the nitrogen generator will be described with reference to FIGS. 2 and 3.

Now, when the nitrogen generator is started, each electromagnetic valve is operated under the control of the control circuit 27, and nitrogen (product gas) is generated.

First, as shown in FIGS. 2 and 3, operations ①, ②, and ② are executed. ■ in Figure 2 indicates air supply valve 9. The take-out valve 19 and the gas discharge valve 13 are opened, and compressed air as a raw material gas is supplied from the compressor 3 to the second adsorption tank 2 .

At the same time, the product gas in the product tank 20 flows back into the adsorption tank 2 from the lower part (upstream side) via the reflux pipe 28 and the pipe 7. Further, the product gas flows backward through the take-out pipes 17 and 16 and flows back into the adsorption tank 2 from the upper part (downstream side). Therefore,
In the adsorption tanks 1 and 2, product gas is simultaneously refluxed from the upper and downstream sides as shown by the broken line arrows in Figure 1, so high-purity nitrogen gas is supplied to the entire interior of the adsorption tanks 1 and 2 in a short time. be able to. Therefore, the second adsorption tank 2 is in a pressurized state due to the compressed air from the compressor 3 and the gas refluxed from above and below, and oxygen is adsorbed to the molecular sieve carbon 2A. This shows a state in which the pressure is reduced due to the opening of the valve 13, and the adsorbed oxygen is desorbed and discharged.

Next, ■ in FIG. 2 shows a state in which the air supply valve 9 is closed and the extraction valve 19 is opened, and the nitrogen gas in the second adsorption tank 2 is being taken out.

At this time, the first @ nursing tank 1 remains in a reduced pressure state.

Next, ▪ in FIG. 2 is a pressure equalization operation in which the pressure equalization valve 22 is opened, and the respective extraction valves 18 and 19, the air supply valve 9, and the gas discharge valve 13 are closed. As a result, the nitrogen-enriched gas remaining in the second adsorption tank 2 is recovered to the first adsorption tank 1, and each adsorption tank 1.degree. 2 becomes equal in pressure. Note that the pressure equalization operation usually takes 1 to 3 seconds.

This means that the first half cycle of one cycle has been completed, and the air supply valve 8. Take-out valve 18. By opening the gas discharge valve 14, as shown in FIG. 3(B).
As shown in FIG. 2, the latter half cycle shown by ■ to ■ in FIG. 2 is repeated. Thus, if one cycle is 120 seconds,
Nitrogen gas can be taken out from the adsorption tanks 1 and 2 in the latter half of each half cycle and supplied to the product tank 20.

In addition, since the gas supply valve 9 is opened in the step (■) above, the compressed gas from the compressor 3 and the product tank 2 are
Product gas from 0 is supplied to the second adsorption tank 2. From the second time onward, the previous ■
Due to the pressure equalization step, a gas with a higher nitrogen concentration than normal raw material gas is supplied.

Therefore, the gas introduced during the pressure equalization step is further forced into the interior of the adsorption tank 2 by the product gas refluxed from the upper part of the adsorption tank 2. Therefore, the gas introduced by pressure equalization can stay in the adsorption tank 2 for a long time until it is taken out to the product tank 20 via the take-out valve 19, and that much more oxygen molecules are adsorbed. In addition, the product gas refluxed from the lower part of the adsorption tank 2 moves from the lower part of the adsorption tank 2 to the upper part and stays in the adsorption tank 2 for a long time until it is taken out by the take-out valve 19. More oxygen molecules contained in the product gas are also adsorbed. Therefore, even if the amount of product gas refluxed from the product tank 20 is the same as before, the adsorption efficiency is increased and the molecular sieve carbon 2A
High purity nitrogen gas is produced.

Therefore, when the take-out valve 19 is opened in step (2), nitrogen gas with a higher nitrogen concentration than usual is accumulated in the product tank 20.

Such reflux effects in the steps (1) and (2) described above can be similarly obtained in the steps (1) and (2) of the adsorption tank 1.

Note that, as described above, it is possible to generate a highly purified product gas, so for example, when the purity of the product gas is maintained at a constant level, a larger amount of gas can be generated than with conventional devices. Therefore, since a highly purified product gas can be generated, the flow rate of the product gas taken out from the product tank 20 can be increased. Furthermore, since the purity of the product gas taken out from the adsorption tank 1.2 in one process is higher than that of the conventional product, the time required for the purity in the product tank 20 to become high is shortened. That is, the effect of shortening the rise time can also be obtained.

In the above embodiment, the take-out pipe 17 is also used as a reflux pipe in order to supply the product gas originally generated in the adsorption tanks 1 and 2 to the product tank 20, and the gas supply valve 8.9 and the take-out valve 8. Since the valves 18 and 19 are used as reflux valves, the configuration is prevented from becoming complicated.

In addition, as shown by the broken line in FIG.
8), and the solenoid valve 3 on the pipe 36
By temporarily opening the valve 7, high-purity product gas cooled to approximately atmospheric temperature is supplied to the tank 3a, so that the high-temperature compressed gas from the compressor 3 accumulated in the tank 3a is heated. Cooled by exchange. Moreover, since the product gas with a lower temperature and dew point than the air dryer 4 is returned to the tank 3a, the compressed air in the tank 3a has higher nitrogen purity than the normal raw material gas, and has a lower temperature and dew point. Therefore, a product gas of higher purity can be obtained.

FIG. 4 shows a second embodiment of the present invention. In FIG. 4, another reflux pipe 30 is connected to the upper part of the product tank 20. A check valve 31 is disposed in the middle of this reflux pipe 30. Reference numerals 33 and 35 indicate reflux pipes branched from the reflux pipe 30, and reflux valves 32 and 34 are provided to connect the first adsorption tank 1. It is connected to the substantially central part of the second adsorption tank 2.

Therefore, during the reflux step, as described above, the gas supply valves 8 and 9 and the take-out valves 18 and 19 are opened, and the reflux valves 32 and 34 are opened in steps (1) and (2). This results in
The product gas in the product tank 20 is taken out from the pipe 17. Piping 1
5.16 and a first reflux path via reflux piping 28. A second reflux path via pipes 6 and 7 and another reflux pipe 30
．． From the third reflux path via 33.35 to each adsorption tank 1.2
is supplied to

Therefore, as shown by the broken line in FIG. 4, the product gas from the product tank 20 is refluxed from three directions: the upper, lower, and middle parts of the adsorption tanks 1 and 2. Even in tank 1.2, product gas can be supplied to the entire interior of adsorption tanks 1 and 2 in a short time.

Furthermore, in the above embodiment, a vertically elongated cylindrical adsorption tank was used as an example, but the shape of the adsorption tank is not limited to this, and even if the adsorption tank has other shapes, multiple reflux pipes may be installed depending on the shape. It may be arranged as appropriate.

Moreover, it goes without saying that the number of reflux pipes may be increased to three or more.

Effects of the Invention As described above, the gas separation device according to the present invention is capable of refluxing the product gas in the product tank into the adsorption tank from multiple locations in the adsorption tank via a plurality of pipes. The product gas refluxed into the tank can stay in the adsorption tank for a long time, and the adsorption efficiency improves accordingly, making it possible to generate product gas with higher purity. In addition, since high-purity product gas can be generated, the flow rate of product gas taken out from the product tank can be increased, and the purity of the product gas taken out from the adsorption tank in one process is higher than before. Therefore, the time required for the purity in the product tank to increase is shortened, and the start-up time can also be shortened. Furthermore, even if the same amount of product gas as before is refluxed, a sufficient reflux effect can be obtained because the product gas is refluxed through multiple pipes, and even if the adsorption tank is vertically long, the entire interior of the adsorption tank can be It has the advantage of being able to supply product gas and also simplifying the configuration by using conventional piping, gas supply valves, and take-out valves.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment of a gas separation device according to the present invention, FIGS. 2 and 3 are process diagrams for explaining each step, and FIG. 4 is a second embodiment of the present invention. FIG. 1.2... Adsorption tank, 1△, 2A... Molecular sieve carbon, 3... Compressor, 32.34... Solenoid valve, 20... Product tank, 2B, 30.33.35.・
・Recirculation piping, 29.31...Check valve.

Claims (1)

[Claims] After supplying compressed raw material gas to an adsorption tank filled with an adsorbent to raise the pressure of the adsorption tank, open the take-out valve of the adsorption tank to collect the gas produced by the adsorbent. A gas separation device for accumulating pressure of product gas in a product tank, wherein a plurality of pipes are provided to connect the product tank and the adsorption tank, and when the adsorption tank is pressurized, a valve is opened to connect the plurality of pipes. A gas separation device characterized in that the plurality of pipes are provided with reflux valves that allow product gas to flow back into the adsorption tank from a plurality of locations in the adsorption tank through the product tank.