JPS6138616A - Gas purifying apparatus - Google Patents

Abstract

PURPOSE:To diminish the energy loss in a gas purifying apparatus of a refrigeration adsorption method by constituting the apparatus of a double structure consisting of the internal and external cylinders, and incorporating both an adsorption cylinder into the internal cylinder and a sheathed heater into the adsorption cylinder. CONSTITUTION:A gaseous raw material is introduced into a feed pipe of the gaseous raw material and cooled via a heat exchanger 13 plus a hose 18 and flowed into the adsorption cylinder 9 which is incorporated in the inside of the internal cylindrical vessel to remove the impure gases and discharged from a drawing-out pipe 15 as the purified gas through the heat exchanger. At this time, liquid nitrogen is fed into the inside of the internal cylindrical vessel from a feed pipe 16 for liquid nitrogen to cool the adsorption cylinder. In case of regenerating the adsorbent, liquid nitrogen is drawn out of the internal cylindrical vessel though a drawing-out pipe 17 for liquid nitrogen and furthermore the vessel is evacuated with a vacuum pump and electricity is conducted to a sheathed heater 5 to heat the adsorbent and the impure gases are desorbed and removed by flowing the regeneration gas reversely to the case of the purification.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a gas purification device that removes impurity gases such as nitrogen gas, -carbon oxide gas, and methane gas contained in hydrogen gas or helium gas by cryogenic adsorption method. More specifically, the present invention relates to a gas purification device in which adsorbent is regenerated by adsorption and direct heating by a sheathed heater built into a cylinder.

In recent years, hydrogen gas in the semiconductor industry, nuclear industry, etc.
The demand for helium gas and the like has increased, and the gases used in these fields are required to have extremely high purity.

[Prior art]

For this reason, various gas purification devices using cryogenic adsorption are used as a means of purifying hydrogen gas or helium gas containing impurity gases such as nitrogen gas, carbon oxide gas, and methane gas to obtain high-purity gas. are used, for example, JP-A-54-42370 and JP-A-55-7565. These devices are mainly composed of an adsorption column, a liquid nitrogen container, a heat insulating container, a heat exchanger, and the like, and adsorption purification of gas by deep cooling and regeneration of adsorbent by heating are repeatedly performed alternately.

That is, during gas purification, by flowing hydrogen gas or helium gas containing impure gas into an adsorption column cooled with liquid nitrogen, the impure gas is adsorbed by the adsorbent and highly purified purified gas is extracted. In addition, when regenerating the adsorbent, after extracting the liquid nitrogen, the adsorption cylinder is heated from the outside with heated air, nitrogen, etc., and the regeneration gas (purified gas) is generated.
By flowing the gas into the adsorption cylinder, the impure gas that has been adsorbed is desorbed and removed.

[Problem to be solved]

However, in conventional equipment that uses such heated gas during remanufacturing, the heating efficiency when heating the gas is extremely low, the heat transfer efficiency is low because the adsorption column is heated from the outside by the heated gas, and the heating gas is circulated. There were various drawbacks, such as the need for blower piping and insulation for these. In addition, directly heating the adsorbent with an electric heater using exposed nichrome wire may cause the adsorbent to be locally heated, and the adsorption tube must be inside a vacuum insulated container.

If the heater is housed in a vacuum chamber, it penetrates the vacuum layer and is exposed to extremely low temperatures, making it difficult to take the lead wire out and select the material for it, and the insulation of the heater is poor, resulting in a short lifespan. There were various problems such as that, and it could not be put into practical use.

[Means for solving problems]

The inventors of the present invention have improved the drawbacks of conventional devices, and have provided a gas purification device that is capable of significantly reducing the loss of energy required for cooling and heating in the gas purification and adsorbent regeneration cycles, and that is also miniaturized. As a result of intensive research, we focused on regeneration of adsorbent by electric heating and arrived at the present invention.

That is, the present invention provides a gas purification apparatus using a cryogenic adsorption method, which has a double structure including an outer cylindrical container and an inner cylindrical container, and one or more adsorption cylinders are accommodated in the inner cylindrical container,
The gas purification apparatus is characterized in that at least one of the adsorption cylinders has a sheathed heater built-in.

The shape of the adsorption cylinder used in the present invention is not particularly limited, but it is preferably cylindrical.

These adsorption cylinders may be used alone, or a plurality of adsorption cylinders may be connected in series through piping.

Book i? Examples of the adsorbent to be filled in the adsorption column in one blade include activated carbon, molecular sieve, and zeolite, and activated carbon is particularly preferred because of its good adsorption performance for impure gases.

1 In the present invention, the heater built into the adsorption cylinder may be a so-called sheathed heater, for example, a heating wire such as a nickel-chromium wire is housed in a metal sheath, and a space inside the sheath is filled with high-purity magnesium oxide or the like. It is a heater (including a so-called micro-heater; hereinafter the same) that is tightly filled with inorganic insulating powder and whose terminal portion is completely sealed with a silicone sealant or epoxy resin. With electric heaters other than such sheathed heaters, local heating of the adsorbent, vacuum discharge, poor insulation, disconnection of heating wires, etc. are likely to occur, and it is impossible to obtain a device that can withstand practical use.

In addition, the lead wires that are led from the terminals of the sheathed heater to the outside of the device are fixed within metal tubes with inorganic fine powder similar to those used in sheathed heaters, and are flexible enough to be bent along with the metal tubes. It will be done.

The number of sheathed heaters built into an adsorption cylinder varies depending on the size of the adsorption cylinder, the amount of heating required, etc. - Although it cannot be generally specified, if the diameter of a cylindrical adsorption cylinder is 100B or less, for example, 1 ~3 pieces. In addition, when a plurality of adsorption cylinders are connected in series by piping, a sheathed heater is usually built in the adsorption cylinder located at least on the most upstream side of the regeneration gas. Of course, it is also possible to incorporate a sheathed heater in other adsorption cylinders. Further, in order to further prevent local heating of the adsorbent and increase heat transfer efficiency to the entire adsorbent, it is preferable to provide a heat sink inside the adsorption cylinder. There are no particular restrictions on the shape or number of heat sinks as long as they can efficiently transmit the heat from the sheathed heater to the adsorbent, but for example, if multiple rectangular metal plates are used, one long side of each is connected to the sheath heater. Alternatively, the heat sinks may be provided radially in contact with the heater sheath. In addition to the hole in the center for passing a sheathed heater or heater sheath,
A plurality of metal disks each having an appropriate number of holes for allowing the waste to freely pass therethrough may be placed horizontally and spaced apart in the vertical direction within the suction cylinder.

In the present invention, the adsorption cylinder is isolated from the outside world by vacuum insulation, but it has a double structure with an outer cylinder container and an inner cylinder container, and the space between the inner peripheral surface of the outer cylinder container and the outer peripheral surface of the inner cylinder container is completely There is a space around the periphery, and this space has an airtight structure to maintain a vacuum state. There is no particular restriction on the shape of the outer cylindrical container and the inner cylindrical container as long as they are cylindrical, but cylindrical shapes are preferred. The space sandwiched between the inner peripheral surface of the outer cylindrical container and the outer peripheral surface of the inner cylindrical container is always kept in a vacuum state during operation of the apparatus.

One or more adsorption cylinders are housed in the inner cylindrical container, and the adsorption cylinders are cooled from the outside by liquid nitrogen (hereinafter referred to as LN2) supplied into the inner cylindrical container during gas purification. Also, when regenerating the adsorbent, LN is removed from the inner cylinder container.
2 is extracted, and while flowing regeneration gas into the adsorption cylinder, the adsorbent is heated by a sheathed heater built into the adsorption cylinder, thereby desorbing and removing the adsorbed impurity gas. During regeneration, it is preferable to maintain the inside of the inner cylindrical container in a vacuum state as well.

In the present invention, it is preferable to provide a heat exchanger between the gas supplied to the adsorption column and the gas exiting from the adsorption column in order to further improve thermal efficiency during purification and regeneration. There is no particular restriction on the location where the heat exchanger is installed; for example, (1) the space above the LN2 liquid level in the inner cylindrical container, (2) the space between the inner peripheral surface of the outer cylindrical container and the outer peripheral surface of the cylindrical container. and (3) the outside of the outer cylindrical container. Among these q, (2) is preferable. Furthermore, in order to improve the cooling efficiency of the raw material gas in the inner cylinder container, a part of the raw material gas supply pipe to the adsorption cylinder can be made into a pre-cooling pipe such as a serpentine pipe or a pipe with cooling fins.

Next, the present invention will be explained in more detail with reference to the drawings.

Figures 1 (f) and (b) are a longitudinal sectional view and a transverse end sectional view, respectively, of an adsorption cylinder with a built-in sheathed heater, and Figures 2 (to) and (b) are the same as those shown in Figure 1. FIG. 2 is a longitudinal sectional view and a transverse end sectional view of an adsorption cylinder in a different aspect from the one shown in FIG.

In FIG. 1, inside a cylindrical container body 3 having a gas inlet 1 and an outlet 2, there is a rod-shaped sheathed heater 5 connected to a lead wire 4 protected by a metal capillary tube. The sheathed heater 5 is provided concentrically with the container body 3 so as to be buried in the filling layer, and the sheathed heater 5 is airtightly fixed to the container body 6 at the upper end 7 of the container body 3 by welding.

A plurality of rectangular heat sinks 8 are arranged around the sides of the sheathed heater 5. ..., 8 are arranged such that one long side is in contact with the sheathed heater 5 and the other long side is arranged radially toward the inner peripheral surface of the container body, and the remaining space is filled with the adsorbent 6. It is used as an adsorption cylinder.

In Fig. 2, instead of directly providing the sheathed heater 5 inside the cylindrical container body 3 having the gas population 1 and the outlet 2, the sheathed heater 5 is housed in a removably cylindrical container with one end closed. A heater sheath 10 is provided concentrically with the container body 3, and the heater sheath 10 is airtightly fixed to the container body 3 at the upper end 7 of the container body 3 by welding, and a heat sink 8°... , 8 are arranged radially, but the adsorption cylinder is similar to that shown in FIG. 1.

FIG. 3 is a longitudinal sectional view showing the principle of the gas purification apparatus of the present invention using a single adsorption column, and FIG. 4 is a longitudinal sectional view of the gas purification apparatus of the present invention using a plurality of adsorption columns. FIG. 5 is a longitudinal cross-sectional view for illustrating the principle, and FIG. 5 is a cross-sectional end view of the gas purification apparatus in which the inner cylinder container and the outer cylinder container are cylindrical in shape in FIG. 4. .

In FIG. 6, an adsorption tube 9 similar to that shown in FIG. 1 or 2 is housed inside the inner tube container 11, and the inner tube container 11 is housed in the outer tube container 12. A cylindrical heat exchanger 13 is provided in a space sandwiched between the outer peripheral surface of the container 11 and the inner peripheral surface of the outer cylindrical container 12. Raw material gas supply pipe 1
4 and the purified gas extraction pipe 15 pass through the wall of the outer cylinder container 12 from the outside of the apparatus, pass through the heat exchanger 13, and further penetrate the wall of the inner cylinder container 11 to reach the inlet 1 and outlet 2 of the adsorption cylinder 9. It is connected to Further, the LN2 supply pipe 16 and the LN2 extraction pipe 17 each penetrate the wall of the outer cylindrical container 12 and are connected to the inner cylindrical container 11. All of these pipes are airtightly fixed at their penetration parts by welding and pipe fittings. Note that a part of the raw material gas supply pipe 14 is formed into a flexible pipe 18 inside the inner cylindrical container 11 . The lead wire 4 protected by a metal capillary tube is guided to the outside by successively passing through the walls of the inner cylindrical container 11 and the outer cylindrical container 12, and is hermetically fixed by a-handles 19 and 20 at each penetrating portion. Gas refiner 482 5
,16ka15. □. 1. .

LN2 is supplied inside the adsorption cylinder 9. This LN2
immersed in water and cooled from the outside. The raw material gas is cooled by the raw material gas supply pipe 14 through a heat exchanger 16 and a flexible pipe 18 in order, and then supplied to the inside of the adsorption column 9, where impurity gas is adsorbed and removed, and purified gas is passed through the heat exchanger 16. The purified gas exits from the exhaust pipe 15. When regenerating the adsorbent, LN2 is extracted from the inner cylinder container 11 and LN is extracted from the extraction pipe 17.
2 is extracted, and the inside of the inner cylinder container 11 is evacuated by a vacuum pump (not shown), and the regeneration gas (
By flowing the purified gas through a path opposite to that used during purification, the adsorbed impurity gas is desorbed and removed.

In Fig. 4, there are four adsorption cylinders 9 with a built-in sheathed heater 5 and three adsorption cylinders 9'' without a built-in sheathed heater 5, each alternately connected to a connecting pipe 21...
This gas purification apparatus has the same structure as that shown in FIG. 3, except that the gas purification apparatus 21 is connected in series.

When refining gas, LN2 is supplied from the supply pipe 16 to the inner cylinder container 1.
LN2 is supplied to the inside of 1, and the adsorption cylinder 9°91#.
..., 9', and 9 are each immersed in this LNz and cooled from the outside. The raw material gas is cooled by the raw material gas supply pipe 14 through the heat exchanger 9#16 and the flexible pipe 18, and is passed through the adsorption cylinders 9, 9', . . . 9119 in the order in which they are connected. The impure gas is adsorbed and removed, and the purified gas is discharged to the outside from the purified gas extraction pipe 15 via the heat exchanger 13. When regenerating the adsorbent, LN2 is extracted from the inner cylindrical container 11 through the LN2 extraction pipe 17, and the inside of the inner cylindrical container 11 is evacuated using a vacuum pump (not shown), and the sheathed heater 5. ..., 5 is energized and the regeneration gas (purified gas) is caused to flow in the opposite path to that used during purification, thereby desorbing and removing the adsorbed impurity gas.

In FIG. 5, a cylindrical outer container 12 and a cylindrical inner container 11 are provided concentrically with each other, and adsorption cylinders 9, 91, . . . , 9', 9 are accommodated therein. Adsorption tube 9.9'
, . . . , 9', 9 are connecting pipes 21., 9' and 9, respectively.・・・
, 21 are connected in series, and a cylindrical heat exchanger 16 is disposed in the space between the outer peripheral surface of the inner cylindrical container 11 and the inner peripheral surface of the outer cylindrical container 12. is assumed to be a cylindrical gas purification device.

〔Effect of the invention〕

The gas purification device of the present invention has the following superior features compared to conventional devices.

t When regenerating the adsorbent, heating efficiency is extremely high, unlike indirect heating using heated gas.

2. When regenerating the adsorbent, the inside of the inner cylindrical container can also be evacuated, reducing thermal energy loss due to gas conduction.

5. There is no need for a heating furnace for externally heating gas, blower 1 piping, or insulation of these, and therefore the equipment can be made smaller, and the heat resistance specifications for sealing materials, valves, etc. can be relaxed, and equipment costs can be reduced. .

Example device: In a device similar to that shown in FIGS. 4 and 5,
7 suction tubes, each container body material 5US504
, Dimensions: 89.1m1x1000ilIIIHx2-T
Of these, four cabinets each having a built-in sheathed heater had a structure similar to that shown in FIG. 2.

In other words, material 5 is used as the heater sheath for each of the four cylinders.
US304, dimensions 19g15!1 x 1000n)i
X 1,2IIlt1 200V as a sheathed heater
, 500W1 dimension 161E1! Mex1o5oxxl, B
The length of the heating part is 809 mm, the material is 5US504 as a heat sink,
Dimensions 50111X 20 (HEjlX 1111t
Sixteen plates were used. In addition, each of the seven adsorption cylinders was filled with 51 pieces of coconut shell activated carbon. Inner cylinder container size 3
18.51! 11 x 1400 WH
Each penetration part was fixed with a Swagelok joint (manufactured by Swagelok, USA).

This equipment was used to purify gas and regenerate adsorbent.

Purification of gas: The space between the outer peripheral surface of the inner cylinder container and the inner peripheral surface of the outer cylinder container is kept in a vacuum state (at 17°C), and LN2 is supplied to the inner cylinder container to make the adsorption cylinder 1196°C. While cooling to
Raw material hydrogen gas containing 0 ppm and 70 ppm of methane gas was supplied at a flow rate of 2 ONfi"/hr, and purification was continued for 10 days. The purified hydrogen gas obtained during this period was purified by TCD and F
As a result of analysis using an ID type gas chromatograph, no nitrogen gas, -carbon oxide gas, or methane gas was detected. The detection limit for these impure gases is nitrogen gas 1
pprnx-carbon oxide 0. lppm, methane gas 0. O
It is 5ppm.

Regeneration of the adsorbent First, the supply of raw hydrogen gas was stopped, and the adsorbent was regenerated. After extracting LN2' from the inner cylinder container, dry nitrogen gas at room temperature was flowed into the inner cylinder container to raise the temperature. When the temperature inside the inner cylindrical container rose to 150° C., the nitrogen gas was stopped, and the inside of the inner cylindrical container was made into a vacuum of 0.1 Torr. Operate the slider to start passing a current of 0.5 to each sheathed heater in each adsorption tube, and gradually increase the current value.2. At the same time as OA, purified hydrogen gas is used as a regenerating gas for the adsorbent at normal pressure from the purified gas extraction pipe in the opposite direction to that used during purification.
I N ml was flowed for hr.

The temperature inside the adsorption column with a built-in sheathed heater continued to rise further, and when it reached 10°C, purified hydrogen gas was flowed at a flow rate of 3 Nyl"/hr for 2 hours. After that,
The temperature inside the adsorption cylinder rose further and reached 180°C. With this process, the current of the sheathed heater was lowered to 1.8 A, but the temperature inside the adsorption cylinder reached 210° C. after 0.5 hr and became constant. At this time, the temperature inside the adsorption cylinder without a built-in sheath heater was 190"C. In this state, the flow rate of the regeneration gas was reduced to INm"/hr, and the temperature was 3.5"C.
br playback continued. During this time, the temperature inside the adsorption cylinder without the built-in sheathed heater was 205℃! It showed a constant value.

At this point, the regeneration is finished, the current is turned off, the vacuum inside the inner container is broken, and nitrogen gas at room temperature is supplied to cool the container for 2 hours.
The temperature inside the adsorption column dropped to 120° C. after 30 minutes. The total power consumption during this period was 7KWH, and the consumption of purified hydrogen gas was 12Nml. Subsequently, the hydrogen gas was purified, and the same results as above were obtained.

Comparative Example After hydrogen gas was adsorbed and purified in the same manner as in the example, the adsorbent was regenerated by changing the conditions as follows.

In other words, instead of having a sheathed heater built into the adsorption tube, an electric furnace and a blower are installed outside the outer cylindrical container, and the nitrogen gas is heated in the electric furnace heated to 420°C and then circulated between it and the inner cylindrical container. The adsorption cylinder was heated. Further, as a regeneration gas, purified hydrogen gas was heated in another heating furnace heated to 500° C. and flowed into the adsorption cylinder.

[Regeneration of adsorbent,]

After extracting the LN2 from the inner cylinder container, dry nitrogen gas at room temperature is flowed into the inner cylinder container, and when the temperature of the inner cylinder container rises to 0℃, it is connected to the above heated nitrogen gas circulation system and adsorption takes place for 1 hour. The temperature inside the cylinder was raised to 100°C. It was heated in an electric furnace adjusted to 500°C while continuously supplying nitrogen gas, and the temperature reached 200°C in 4 hours. The temperature of the electric furnace for nitrogen gas heating was lowered to 400°C, and the temperature was further increased by 3°5br@.

The power consumption required for regenerating the adsorbent was 58 KWH, excluding the driving power of the circulation blower, and the consumption of purified hydrogen gas was 12N1rL'. Subsequently, the hydrogen gas was purified, and the same results as in the example were obtained.

[Brief explanation of the drawing]

Figure 1) and (→) are a vertical cross-sectional view and a cross-sectional end view of an adsorption cylinder with a built-in sheathed heater, respectively, and Figures 2 (to) and (b) are different from those in Figure 1, respectively. FIG. 3 is a vertical sectional view showing the principle of the gas purification apparatus of the present invention using a single adsorption column, and FIG. 4 is a longitudinal sectional view showing a plurality of adsorption columns. In order to demonstrate the principle of the gas purification apparatus of the present invention using an adsorption cylinder, 1.
...Inlet 2...Outlet 3...Container body 4...
Lead wire protected by thin metal tube 5... Sheathed heater 6... Adsorbent 7... Upper end 8... Heat sink -
9 and 91... Adsorption tube 1 Pa0... Heater sheath 1
1... Inner cylindrical container 12... Outer cylindrical container 13... Heat exchanger 14... Raw material gas supply pipe 15... Purified gas extraction pipe 16... LNz supply pipe 17... L
Nz extraction pipe 18...Serpentine pipe 19 and 20 Joint
and 21...connection piping. Patent applicant Fumio Takasaki, representative of Nippon Bionics Co., Ltd.

Claims (1)

[Claims] A gas purification device using the cryogenic adsorption method has a double structure consisting of an outer cylindrical container and an inner cylindrical container, and the inner cylindrical container has one
or a plurality of adsorption cylinders are accommodated, and at least one of the adsorption cylinders is
A gas purification device featuring a built-in sheathed heater.