JPH0221914A - Method of regenerating lubricating oil for vacuum pump - Google Patents

Abstract

PURPOSE:To remove the contaminants such as acids and solid extraneous matter in the lubricating oil of a vacuum pump with high accuracy by using a filter element contg. acrylic water absorptive fibers impregnated with water. CONSTITUTION:A filter device 22 having a doughnut-shaped filter element 28 packed with the acrylic water absorptive fibers impregnated with water is installed in the lubricating oil circuit of a semiconductor producing apparatus. The oil from a drain port 26 is introduced through a pump 20 from a bottom inlet 26 to a filter tank 24 of the filter device 22. The oil rises to pass the inside of the filter element 28 and returns from a bottom outlet 30 to an oil feed port 18. Since the acrylic water absorptive filters have a moisture layer on the fiber surface, the acids in the oil are replaced with the moisture layer and are removed. The extraneous matter in the oil is stuck to the fiber surface and is thereby removed. The regenerated lubricating oil is returned to the oil feed port 18.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a filtration method, and more particularly to a method for regenerating lubricating oil for a vacuum pump.

Conventional vacuum pumps with small limbs, especially vacuum pumps used in semiconductor manufacturing equipment, are contaminated with large amounts of corrosive gases and are accompanied by reaction products of various gases, some of which are treated with exhaust equipment, but vacuum pump oil The mixed part contaminates and deteriorates the oil. Therefore, for stable operation of the vacuum pump, these impurities (acids,
Oxidation products.

(metal powder, dust, etc.) must be filtered and removed.

Conventional techniques for this purpose include:

1. Filter one type (cellulose, glass fiber,
sintered material, etc.) 2. Adsorbent filter one type (activated alumina filter 3)
Activated clay filter, etc.) 3. Electrostatic filtration method 4. Combination method 5. Extraction separation method (adding water or an aqueous solution to oil to extract pollutants into water and separating them based on the difference in specific gravity) 1. Filter single method There are two types of filters: pleated filters and rolled tissue filters, which remove impurities on the surface of the filter medium.

This type of filter only removes solid contaminants, the filtration accuracy is relatively low, and there is a lot of oil loss when changing the filter.

2 Adsorbent filter This is a one-type filter that mainly uses activated alumina, and if the powder is finely shifted to improve filtration performance, clogging is likely to occur. The amount of acid adsorbed is determined by the filling amount, so increasing the amount of adsorption will increase the size. Filters are expensive and there is a lot of oil loss when changing filters.

3 Electrostatic filtration method This is a collection device using static electricity between opposing electrode plates, and the device for generating static electricity becomes large. It cannot be used under conditions where current easily flows, that is, oil with a high acid value, oil mixed with water, highly contaminated oil, etc. No acid removal function. Furthermore, the amount of oil used is large,
Filtration speed is slow.

4 Combination method A Pleated type and activated alumina filter Large impurities are removed using the pleated type filter, and small impurities are removed and acids are adsorbed using the activated alumina filter.

A large amount of oil is used, and a significant amount of oil is lost when replacing the filter. It also becomes larger and more expensive.

B: Electrostatic filtration and activated alumina adsorption filter Due to space constraints, the amount of activated alumina packed is small, the amount of acid processed is small, oil loss is large, and it is expensive.

5 Extraction separation method Contaminants are extracted by adding an aqueous solution to the oil and separated based on specific gravity.

Although effective against water-soluble pollutants, filtration accuracy is poor when various impurities coexist.

SUMMARY OF THE INVENTION The object of the present invention is to overcome the drawbacks of the above-mentioned known filtration methods;
An object of the present invention is to provide an oil regeneration method suitable for removing contaminants and solid impurities in vacuum pump lubricating oil.

1' A method for regenerating vacuum pump lubricating oil containing water-soluble contaminants according to the present invention, in which a filtration element is used for circulation filtration, and the filtration element is made of water-impregnated acrylic water-absorbing fibers. including.

A filtration element using acrylic water-absorbing fibers has a water layer on the surface of the constituent fibers, so it can remove acids mixed in vacuum pump oil. Furthermore, since this fiber has high fiber elasticity even when water is absorbed, the density of the filter agent does not increase excessively, and the required filtration resistance can be maintained. Therefore, using one type of element, removal of impurities and acid can be performed with high precision.

Embodiments and drawings illustrating the present invention will be described.

The figure shows an example in which the method of the present invention is applied to a closed circulation type filtration device. The vacuum pump 10 has an intake port 12 and an exhaust port 14, and the intake port 12 is connected to necessary equipment.

The lubricating oil circuit runs from the drain port 16 to the pump 20. Filtration device 2
A circuit 32 is formed which connects to the fuel filler port 1 through 2.

Oil is introduced into the filter tank 24 of the filtration device 22 from the bottom inlet 26, and the oil rises and passes through the annular filter element 28.
It passes through the inside and returns to the fuel filler port 18 from the bottom outlet 30.

Examples of implementations of filter elements 28 suitable for the configuration described above are as follows.

Shape, outer diameter 1B (1mm, height 115mm donut-shaped) Fiber filling rate 5-50χ Fiber moisture content 0.1-30χ Fiber type Acrylic water-absorbing fiber Other fibers, non-woven fabric, cotton-like element, thread-wound element, etc. may be mixed in.

Pump Pressurized oil circulation pump (0.1-15It/m1
n) The configuration shown is a continuous circulation hermetic filtration device directly connected to a vacuum pump, but a bypass is formed in one circuit, or the vacuum pump is supplied with oil from a tank, and the filtration device is connected to a used tank or another tank. Of course, lubricating oil can also be regenerated.

An embodiment of the illustrated filtration apparatus of the present invention will be described below as an example of regenerating vacuum pump oil in a chlorine-based dry etching process.

Regeneration processing condition oil Fluorinated synthetic oil (BARRIERTA J25)
Processing oil amount: 101 Circulating pump flow rate: 1.3 It/min Filter tank capacity: 3.5 it Processing temperature: Room temperature element 180 Φ Strong acid value 1
50 mg/l Analysis value processing time after treatment hr 0123 Weight contamination degree mg/100m1106 13 1.2 0
Strong acid value mg/l 150 22 1.8 0 An example of continuous use in a fluorine-based dry etching process is shown in Table 1 below under the same conditions as other known filtration methods.

Table 1 Viscosity 73.6 cst/40゜Total acid value O Weight contamination degree O Vacuum pump Japan Vacuum Giken o-950 Atmosphere gas used Freon Compared to conventional treatment method, 1 viscosity, total acid value, and contamination degree can be maintained for a long period of time It has become possible to maintain and control the system over a period of time.

Acid Removal The acrylic water-absorbing fiber filter element according to the present invention can contain 0.1-30χ water, replacing the acid in the oil with water, suppressing the increase in acid value, Produces a neutralizing effect.

2. Removal of contaminants and reaction products Contaminants adhere to the fiber surface, accumulate sequentially, and are processed and removed.

3. Removal when acid and contaminants coexist Contaminants adhere to the fiber surface, and the acid is replaced by the water layer and removed.

4. Adaptability to usage conditions The filter element of the present invention can be easily adjusted in density, moisture content, and processed into various shapes, and can be easily adapted to various usage conditions.

That is, if there is a large amount of contaminant products mixed in, the density should be reduced. If there is a large amount of acid mixed in, increase the water content. This work involves adjusting the filter element.

It can be easily filled.

By using the filtration device of the present invention, used oil from vacuum pumps can be recycled to the required specifications, which is extremely effective in semiconductor manufacturing.

[Brief explanation of the drawing]

The figure is a diagram showing an example of a method for regenerating vacuum pump lubricating oil according to the present invention. 100. Vacuum pump 123. Intake port 149. Exhaust port 161. Drain port 181. Fuel filler port 200. Circulation pump 22.6 Filtration device 240. Filter tank 28°, filter element

Claims (1)

[Claims] 1. A method for regenerating lubricating oil for a vacuum pump containing water-soluble contaminants, in which a filtration element is used for circulation filtration, the filtration element is a water-absorbing acrylic oil. A method for regenerating lubricating oil for a vacuum pump characterized by containing fibers.