JPH0733861Y2 - Gas purification equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a gas purifying apparatus for removing foreign matters such as moisture and dust from gas.

[Prior Art] When generating an extremely high vacuum, surface analysis, especially surface analysis in vacuum, or semiconductor manufacturing, it is very important that impurity gas or moisture is present in the required gas. I hate to remove them from the gas. In particular,
In order to quickly reduce the vacuum pressure in the chamber or the like, it is necessary to reduce the water content in the chamber as much as possible.

In order to remove such water, a sorption pump is conventionally filled with a porous adsorbent called a molecular sieve (an artificially made zeolite), and the water is removed by a molecular sieve cooled with a cooling material such as liquid nitrogen. There is a method of adsorbing and removing impurities and gas. However,
This molecular sieve hardly adsorbs gas molecules having a molecular diameter larger than the diameter of its own pores, so if the gas has a molecular diameter smaller than the pore diameter,
Even if it is a necessary gas, it is adsorbed, so there is a limitation in use. In addition, since heat conduction is poor and it takes time to cool, there is a problem that it takes time to start the work.

In order to deal with such a problem, the inventor of the present invention has previously proposed a gas purifying device capable of efficiently removing moisture and dust from gas in Japanese Utility Model Application No. 63-168008 (see Japanese Utility Model Publication No. 5-3473). Proposed.

This gas purification device has the advantage that, unlike the conventional adsorption and removal of moisture by molecular sieves, there is no adsorption of the required gas and the start of work is quick, but there is a lack of consideration regarding the temperature control of the cold material, Means for maintaining the cold material at a substantially constant temperature are cumbersome.

[Problems to be Solved by the Invention] An object to be solved by the present invention is to provide a gas purifying apparatus in which temperature control of a cold material is easy.

[Means for Solving the Problems] In order to solve the above problems, the gas purification apparatus of the present invention has a pipe line to which the primary cold material is supplied, has a higher freezing point than the primary cold material, and has a primary cold material. A heat-insulating cold material container filled with a secondary cold material that is cooled to a temperature lower than the freezing point, and a closed container in the cold material container made of a material having good heat conductivity, the closed container, It is characterized by being provided with an inlet and an outlet of purified gas, and a sintered metal filter for removing moisture from the gas flowing through the container by cooling and liquefaction.

[Operation and Effect of Invention] After supplying the primary cooling material to the pipeline and cooling the secondary cooling material filled in the cooling material container to a temperature lower than its freezing point, the purified gas is supplied to the closed container.

By supplying the purified gas, moisture in the gas is removed by liquefaction by cooling and dust is also removed, thereby warming the secondary cooling material, but the latent heat of melting causes the secondary cooling material to be relatively long. In order to maintain a constant temperature for a period of time, the time interval for cooling the secondary cold material by the primary cold material can be lengthened, so the temperature control of the cold material is simple.

In addition, since the filter is made of sintered metal with good thermal conductivity, the temperature of the filter drops quickly due to the secondary cooling material, so not only can work be started in a short time, but also the adsorption efficiency due to the temperature drop. Can be increased.

In addition, since the purified gas passes through a large number of small gaps in the sintered metal filter, there is a high probability that gas molecules will collide with the filter and the collection capacity is good, and since it is not as porous as the molecular sieve, it absorbs even the necessary gas. And the gas flow rate can be increased.

[Embodiment] FIG. 1 shows an embodiment of the present invention. This gas purification apparatus has a heat-insulating cold material container 3 having a pipe line 1 to which a primary cold material is supplied and filled with a secondary cold material 2. And a closed container 4 immersed in the secondary cooling material 2 described above, and the pipe line 1 and a supply pipe 5 and a discharge pipe 6 for supplying and discharging purified gas to and from the closed container 4 of the cold material container 3. The temperature sensor 8 is installed in the cold material container 3 through a hole formed in the heat insulating lid 7, and the temperature sensor 8 is installed in the cold material container 3. It is connected to a controller 13 which controls a supply device 14 for the primary cold material to the.

As the primary cooling material, for example, liquid nitrogen can be used, and the secondary cooling material uses a cooling material having a higher freezing point than this, for example, ethanol, and is cooled to a temperature slightly lower than the freezing point by the primary cooling material. It

The closed container 4 is made of a material having good heat conduction, and is provided with a plurality of filters 9a, 9b, in a direction substantially orthogonal to the flow direction of the purified gas.
9c is joined to the inner wall so as to maintain high thermal conductivity. This filter has a mesh close to the mean free path of the purified gas, for example, by sintering particles or fibers of a metal having good heat conductivity such as stainless steel or brass, or by sintering a composite thereof. It was formed. Specifically, in consideration of easiness in production, the particles or fibers may be configured to have a fluid passage gap of about several μm, but for example, a smaller gap of 1 μm or less (preferably 0.1 μm or less). μm) is desirable. The plurality of filters 9a, 9b, 9c, the filter 9a of the gas inflow side is coarse, it is good to sequentially finer toward the filter 9c of the gas outflow side, especially the gas inflow side that adsorbs a large amount of moisture. It is better to use a coarser filter.
In addition, the closed container 4 has a heater 10 that heats by circulating a heating fluid, and heats it under high vacuum in advance before starting work.
Allow sufficient moisture to be released inside.

In the above-described embodiment, when the primary cooling material is supplied from the primary cooling material supply control device 14 to the pipe line 1, the secondary cooling material 2 filled therein is cooled, and the closed container 3 also passes through the secondary cooling material 2. To be cooled.
In this case, the temperature of the closed container 4 is from the outer periphery to the filters 9a, 9
Since the temperature of each filter drops toward the center of b, 9c and the filters 9a, 9b, 9c are made of a material with good heat conduction, the temperature of each filter will drop more quickly compared to the molecular sieve, so start the work in a short time. You can

When the temperature sensor 8 detects that the secondary cooling material 2 has been cooled to a temperature slightly lower than its freezing point, the supply control means stops the supply of the primary cooling material and supplies the required purified gas from the supply pipe 5. It The supplied gas flows to the exhaust pipe 7 through each filter, and liquefies (adsorbs) an impurity gas (vapor) whose vaporization temperature is higher than that of the secondary cooling material 2 to filter 9a, 9b,
The clean gas, which has been collected by 9c and from which the impurity gas and the water have been removed, flows out of the apparatus through the discharge pipe 6. In this case, the lower the temperature, the better the adsorption of molecules, so that the adsorption efficiency can be increased.

Further, since the purified gas passes through the micron-shaped gaps in the sintered filters 9a, 9b, 9c several hundred times, the gas molecules have a high probability of colliding with the filter and have a good collection ability, and moreover,
Since it is not as porous as the molecular sieve, it does not adsorb the required gas, and the flow rate of the gas can be increased. Furthermore, if the filter is made of stainless steel,
It is possible to dehumidify corrosive gas and remove dust.

Although the secondary cooling material 2 is heated by the supply of the purified gas, the secondary cooling material 2 cooled to a temperature slightly lower than the freezing point may maintain a substantially constant temperature for a relatively long time due to latent heat of melting. it can. Therefore, the time interval for cooling the secondary cooling material 2 by the primary cooling material can be lengthened, and the temperature control thereof is easy.

Since the above embodiment is a storage type, when purifying the purifying gas continuously, two or more purifying gases are installed, and while one purifying device removes impurities, the other closed container is used. 4 is dehumidified by suction with a vacuum pump while heating with a heater in the container. Also in this case, since the heat conduction of the filters 9a, 9b, 9c is good, the time required for dehumidification can be shortened.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view of an embodiment of the present invention. 2 ... Secondary cold material, 3 ... Cold material container, 4 ... Closed container, 5
…… Supply pipe, 6 …… Discharge pipe, 9a, 9b, 9c …… Filter.

Claims (1)

[Scope of utility model registration request] 1. A heat insulating material having a pipe line to which a primary cold material is supplied, filled with a secondary cold material having a freezing point higher than that of the primary cold material and cooled to a temperature lower than the freezing point by the primary cold material. Of the cold material container, and a closed container in the cold material container made of a material having good heat transfer, the closed container, the purified gas inlet and outlet, and the gas flowing through the container to liquefy the moisture A gas purification device, comprising a sintered metal filter for removing the gas.