JPS5822243B2 - How to use the information that you need to know - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device that uses ultrapure water as cleaning water, detects organic solvents mixed in the cleaning wastewater, and separates it from the cleaning wastewater. The purpose is to prevent the contamination of organic solvents, which can be a hindrance to high-purity reuse.

Recently, large amounts of ultrapure water are used in industrial fields that use ultrapure water as cleaning water, for example, in the process of cleaning semiconductor integrated circuit elements such as transistors and ICs.

Since ultrapure water has a high production cost and its cleaning waste water has a high purity as water, it is possible to reuse it.
There has been a demand for water that is less than IrL to be reprocessed using an ultrapure water production device and used as cleaning water.

However, in some of the processes that use cleaning water, organic solvents such as phlegm and acetone are used, so these organic solvents often temporarily get mixed into the cleaning wastewater, and this cannot be directly used. When treated with a pure water production equipment,
Reprocessing of cleaning wastewater has been avoided because organic solvents can contaminate the equipment and seriously impede the ultrapure water production function.

Another possibility is to separate and remove the organic solvent in the cleaning wastewater, but since there is no practical means to promptly detect organic solvents mixed into the cleaning wastewater, It has been difficult to effectively separate the

The present invention is an apparatus for detecting and separating organic solvents mixed in cleaning waste water that has improved the above-mentioned drawbacks, in which the cross-sectional area of the detection tank in the upper part of the washing waste water tank is formed to be smaller than the cross-sectional area of the washing waste water tank.
The electrodes of the conductivity meter are installed in a detection tank with a small cross-sectional area, and the conductivity and specific gravity of organic solvents are much smaller than those of cleaning wastewater, as shown in the table below. This system promptly and properly detects the mixing of organic solvents into the waste water and separates the cleaning wastewater from the organic solvents.

Table 1 Electrical conductivity Specific gravity Ultrapure water 5.5μu/cm or less 1.0 Washing wastewater 20.0μu/crfL or less 1.01~
1.05 Kinren 0.003 μu 7cm or less 0
．． 88 Acetone 0.002.411 /cvt or less 0.80 or less An example of an embodiment of the present invention will be described with reference to the drawings. A detection tank 2 is provided at the upper part of this cleaning drainage tank 1, and this detection tank 2
The cross-sectional area of the washing and draining tank 1 is formed to be smaller than the cross-sectional area of the washing and draining tank 1.

The electrode 3 of the conductivity meter 4 is attached to the inside of the detection tank 2, and if necessary, the detection tank 2 may be sealed and filled with nonflammable gas.

Furthermore, it is more effective to install a large number of inclined plates 12 at intervals in the center of the washing and draining tank 1.

Further, an inflow pipe 5 for washing wastewater is connected to the upper part of the inclined plate 12 of the washing drainage tank 1, and an outflow pipe 6 for washing wastewater that does not contain organic solvents is connected to the bottom of the same type, and an outflow pipe 6 for washing wastewater that does not contain organic solvents is connected to the bottom of the tank 1. The drainage pipe 9 is connected.

The outflow pipe 6 for washing wastewater is formed into a riser tube shape, and an opening 10 is provided at its tip, and the electrode 3 in the upper detection tank 2 of the washing wastewater tank 1 is attached to the upper part of the outflow pipe 6. connects the overflow pipe 7 to a location corresponding to the position.

Next, to explain the operation of the present invention, when the valves 14 and 8 are opened, the cleaning wastewater flows from the inflow pipe 5 into the cleaning drainage tank 1 via the rectifying plate 11, the water level in the tank rises, and the detection tank 2
When the electrode 3 reaches the position where it is attached, it flows out from the overflow pipe 7 via the outflow pipe 6.

If only the washing waste water is flowing into the tank, the electrode 3 is in contact with the washing waste water, so the conductivity meter 4 indicates the conductivity of the washing waste water.

Therefore, in this case, the cleaning waste water may continue to flow out from the overflow pipe T and be treated with an ultrapure water production device (not shown).

However, when organic solvents are mixed into the cleaning wastewater and flow into the cleaning wastewater tank 1, the organic solvents, which have a lower specific gravity than the cleaning wastewater,
It floats to the detection tank 29 and forms a layer on the water surface of the cleaning wastewater, separated from the water.

At this time, since the cross-sectional area of the detection tank 2 is smaller than the cross-sectional area of the cleaning drainage tank (usually ~115), even if a small amount of organic solvent is mixed in, a thick layer of organic solvent will be present in the same area. Thus, the organic solvent can be quickly and accurately detected by the electrode 3.

Therefore, if an organic solvent mixes into the cleaning wastewater, the electrode 3 will come into contact with the organic solvent and the conductivity meter 4 will indicate the conductivity of some or all of the organic solvent. The indicated value is smaller than the above-mentioned indicated value for cleaning waste water.

Therefore, the change in the indicated value of the conductivity meter 4 is electrically detected and the valves 14 and 8 are closed to stop the inflow and outflow of cleaning wastewater.

In addition, in the above case, the inclined plate 1 is installed in the cleaning drainage tank 1.
2, the overflow pipe T is separated by the separating action of the inclined plate 12.
It is possible to very effectively prevent organic solvents from being mixed into the cleaning wastewater that flows out before the valve 8 is closed.

After detecting the inflow of the organic solvent and stopping the inflow and outflow of the cleaning wastewater, the valve 13 is then opened and the cleaning wastewater and organic solvent in the cleaning drainage tank 1 are drawn out from the discharge pipe 9.
When this is completed, the valve 13 is closed and the valve 14 is opened again to restart the inflow of cleaning waste water, and after confirming that the liquid level is in contact with the electrode 3, the valve 8 is opened.

As described above, according to the present invention, even if a small amount of organic solvent is mixed into cleaning wastewater, this can be quickly and properly detected, and the cleaning wastewater containing the organic solvent can be removed from the system. It is now possible to obtain only cleaning wastewater that does not contain organic solvents, and as a result, if cleaning wastewater that does not contain organic solvents is treated with an ultrapure water production equipment, it can be easily made into ultrapure water.
Since it can be reused as cleaning water, the cost of using ultrapure water as cleaning water can be significantly reduced.

[Brief explanation of the drawing]

The drawing is an explanatory longitudinal cross-sectional view of the detection and separation device for organic solvents mixed in cleaning waste water according to the present invention. 1...Cleaning drainage tank, 2...Detection tank, 3
... Electrode, 4 ... Conductivity meter, 5 ...
...Inflow pipe, 6...Outflow pipe, 1...
Overflow pipe, 8... Valve, 9... Discharge pipe, 1
0... Opening, 11... Current plate, 12...
... Slanted plate, 13 ... Valve, 14 ... Valve.

Claims (1)

[Claims] 1 When ultrapure water is used as cleaning water and the cleaning wastewater is treated with an ultrapure water production equipment and reused as cleaning water, organic solvents with a specific gravity smaller than water are temporarily mixed into the cleaning wastewater. In some cases, a detection tank with a cross-sectional area smaller than the cross-sectional area of the cleaning drainage tank is installed above the cleaning drainage tank in communication with the cleaning drainage tank, and an electrode of a conductivity meter is installed in the detection tank. In addition, an inflow pipe for washing wastewater is attached to the upper part of the washing wastewater tank, a discharge pipe for washing wastewater is attached to the lower part of the washing wastewater tank, and an outflow pipe for washing wastewater in the form of a riser opens at the upper part of the detection tank. The electrodes in the detection tank are installed in the outflow pipe of the cleaning wastewater, and the overflow pipe is connected to the location corresponding to the position, and the cleaning wastewater flows in from the inflow pipe of the cleaning wastewater. The organic solvent is configured to flow out from the overflow pipe, and after the organic solvent is detected by an electrode in the detection tank, the cleaning wastewater in the cleaning drainage tank and the detection tank is discharged. Organic solvent detection and separation equipment.