JP2001347271A - Method and apparatus for cleaning drain - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and apparatus for cleaning a drain, capable of obtaining stable and high oil-water separation ability at low cost, regardless of treatment quantity and reducing the labor. SOLUTION: When oil and water are separated by demulsifying an oil component suspended in water by electrolysis in an electrolyte cell to float the same, an electrolyte solution is supplied to the drain while the electric conductivity of the drain is detected to prepare a liquid to be treated set to desired electric conductivity and this liquid is supplied to the electrolytic cell and power is applied across the electrodes of the electrolytic-cell corresponding to the supply amount of the liquid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for purifying drain, and more particularly to a drain suitable for separating and recovering oil from drain discharged from an air compressor and discharging clean water to a public sewer. The present invention relates to a purification method and an apparatus therefor.

[0002]

2. Description of the Related Art In an air compressor which is generally widely used in the industry, moisture in the air is condensed during a compression process, and lubricating oil of the compressor is suspended in the water. The mixed drain is discharged. In large reciprocating compressors and oil-cooled screw compressors, the concentration of oil contained in the drain is high, and discharging this drain to the general sewer will cause water pollution and pollution. This would violate the wastewater standards of the Water Pollution Control Law.

[0003] Therefore, it is necessary to separate the oil, which is a main harmful substance in the drain, from the water, collect the oil, perform a process such as recycling and incineration, and discharge only the purified water to a general sewer.

[0004] As a conventional oil-water separation method suitable for drainage purification of oil with very small oil droplets or oil with a large amount of suspended matter or emulsified oil, there is an electrolytic flotation method (Kanagawa Prefectural Environment Department Showa)
57-3-31 Issued "Wastewater Treatment Technology Facility Management Manual-Oil-Containing Drainage-").

[0005]

In this prior art, an electrolyte is added to a drain having poor electric conductivity to lower the electric conductivity to promote electrolysis. It has been found that the expected separation performance cannot be obtained as the processing amount increases.

That is, when the amount of electric power supplied to the electrolysis tank is increased to improve the oil / water separation performance, the dissolution of the electrode metal proceeds, and the filter provided downstream of the electrolysis tank frequently becomes clogged. This results in lower processing efficiency and higher costs.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method and an apparatus for drain cleaning which can obtain a stable high separation performance of oil and water at a low cost irrespective of the amount of treatment and which can be performed without any trouble.

[0008]

A feature of the present invention to achieve the above object is that the oil suspended in water is demulsified by electrolysis in an electrolysis tank, coagulated, floated, and floated. In the drain purification method for performing separation, an electrolytic solution is supplied to the drain while detecting the electric conductivity to supply a treatment liquid having a desired electric conductivity to the electrolysis tank, and the electric power according to the supply amount is supplied. Is applied to the electrode of the electrolysis tank.

A feature of the present invention that achieves the above object is a drain purification method in which an oil component suspended in water is demulsified, coagulated and floated by electrolysis in an electrolysis tank to separate oil and water. In the apparatus, a tank provided with a drain and an electrolyte solution supplied with a means for detecting electric conductivity,
A control valve for controlling the amount of electrolyte solution supplied to the tank, a control means for adjusting the opening of the control valve in accordance with the electric conductivity detected by the detection means, and maintaining the electric conductivity in the tank at a desired value;
It has power supply means for applying power to the electrodes of the electrolysis tank in accordance with the supply amount of the processing liquid having the desired electrical conductivity by mixing the drain and the electrolyte solution to the electrolysis tank. .

From the viewpoint of the principle of oil-water separation by electrolysis, an electrode for demulsifying and dissolving a suspended (emulsified oil) oil component in an electrolysis tank (hereinafter abbreviated as an electrolytic tank). Hydrogen / oxygen gas generated by aggregation of metal components or oil additives (hereinafter referred to as scum) until they can float, or by electrolysis with aggregates that do not allow them to float And the amount of electricity required to float.

Therefore, it is sufficient to measure the electric conductivity in the electrolytic cell to give a necessary amount of electricity. However, a new drain continuously flows into the electrolytic cell, and the generated hydrogen The amount of suspended oil present in the electrolytic cell is constantly changing due to convection caused by the rise of oxygen gas. Therefore, it was found that it was difficult to detect the amount of oil in the electrolytic cell from the measurement of electric conductivity and suppress the dissolution of the electrode metal, while making the amount of electricity appropriate (necessary) for oil-water separation.

Therefore, the electric conductivity of the drain to which the electrolyte solution has been added is measured outside the electrolytic cell, the oil content is indirectly detected from the measurement result, and an appropriate electric current for separating the supply amount of the electrolyte solution from the oil-water separation. -Control is performed so that the voltage value is obtained.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a drain purifying apparatus according to the present invention. In FIG. 1, 1 is a compressor,
Reference numeral 2 denotes a drain supply amount detecting means, that is, a flow meter for measuring the supply amount of the drain discharged from the compressor 1 to the tank 3 and temporarily stored. 4 is a tank for storing the electrolyte solution, 5 is an electromagnetic (control) valve for controlling the supply amount of the electrolyte solution to be supplied to the tank 3, and 6 is a process in which the drain and the electrolyte solution in the tank 3 are mixed by a stirring propeller (not shown). A sensor for measuring the electric conductivity of the solution, 7 is a pump for sending the treatment solution in the tank 3 to the electrolytic cell 8, A and K are a plurality of anode and cathode electrodes arranged vertically in the electrolytic cell 8, 9 is A power supply for applying a direct current between the electrodes A and K, 10 is a current control device, and S is an electrolytic cell 8
, A reference gravity separation tank 11 for performing solid-liquid separation of the processing liquid, and a drain port Ex of the specific gravity separation tank 11.
And a filter unit that removes a solid that may pass through without receiving the supernatant from the specific gravity difference separation tank 11, and the treatment liquid passing through the filter is drained to a sewage system as wastewater.

A control device 13 adjusts the opening of the solenoid valve 5 based on the measurement results of the flow meter 2 and the sensor 6,
From the supply amount of the electrolyte solution supplied from the tank 4 to the tank 3, the number of rotations of the motor attached to the pump 7 is controlled by the motor driver 14 to adjust the amount of the processing solution to be sent to the electrolysis tank 8, and then sent to the electrolysis tank 8. The electric power to be applied to the current controller is indicated based on the amount of the liquid and the electric conductivity. Power supply 9, current control device 1
0 and the control device 13 are power supply means for applying electric power to the electrodes of the electrolysis tank in accordance with the supply amount of the processing liquid having the desired electrical conductivity to the electrolysis tank by mixing the drain and the electrolyte solution in the tank. It is.

An example of the electrolyte solution in which the electrolyte solution is stored in the tank 4 is public tap water. Tap water contains hypochlorous acid in a fixed amount for sterilization, and has an advantage that the electric conductivity is not only stable and effective as an electrolyte solution, but also does not pollute the environment when discharged from the filter unit 12. is there.

The ratio of oil and moisture in the drain discharged from the compressor 1 varies greatly depending on the season. Although a large amount of water is contained in summer, almost no moisture is contained in winter. When this variation was further examined, it was confirmed that the electric conductivity of the drain itself hardly fluctuated.

The present invention is based on this result, and the controller 13 supplies the electrolyte solution in the tank 3 and measures the electric conductivity with the sensor 6 in a state where the electrolyte solution is mixed and homogenized. The supply amount of the processing liquid from the tank 3 to the electrolysis tank 8 is controlled. That is, the supply amount of the electrolyte solution is adjusted by the solenoid valve 5 in accordance with the detected electric conductivity, and the electric conductivity of the treatment liquid in the tank 3 is adjusted to the desired electric conductivity. Send to tank 8. The liquid supply amount of the pump 7 may be set by the measurement result of the flow meter 2 or by opening and closing a float switch provided in the tank 3.

Since the electric conductivity of the processing solution sent by the pump 7 is measured by the sensor 6, the controller 13 instructs the electric power to be applied to the current controller according to the result.

FIG. 2 shows the relationship between the amount of drain (content) and the electrical conductivity in a fixed amount of the processing solution. The greater the amount of drain (content) in the processing solution, the lower the electrical conductivity.

FIG. 3 shows the relationship between the electric conductivity of the treatment liquid and the control current (electric power) required for oil-water separation. The lower the electric conductivity, the larger the control current required for electrolysis.

Since the amount of drain discharged from the compressor 1 fluctuates with the season, the tank 3 may overflow when the input flow rate of the electrolyte solution 13 is increased in order to maintain a desired electric conductivity corresponding to the discharge amount. The flow rate of the drain discharged from the compressor 1 is measured and detected by the flow meter 2, the controller 13 calculates the total inflow amount in the tank 3, and adjusts the rotation of the pump 7 by the motor driver 14.

The current (required amount of electricity or electric energy) applied to the electrodes A and K in the electrolytic cell 6 is determined from the electric conductivity of the processing solution measured by the sensor 6 and the number of revolutions of the pump 7 as shown in FIG. Set. In FIG. 4, the characteristic curves for the case where the drain (content) amount is large and the case where the drain (content) amount is small indicate that the current applied to the electrodes A and K is changed depending on the desired electric conductivity of the processing solution.

The filter unit 12 has an oil adsorbent and an activated carbon layer therein to remove remaining oil, electrolytic by-products such as dissolved electrode metal components, and the like. Is applied, the dissolution of the electrode metal is suppressed, and the amount of the electrolytic by-product is reduced, and is discharged together with the scum S to a scum receiver (not shown), so that the filter unit 12 does not clog. The frequency of replacement of the filter, the activated carbon layer, and the like in the filter unit 12 is greatly reduced, so that not only the time and effort for replacement can be saved, but also the consumption cost for replacement is reduced and the cost is reduced.

Further, as described above, the ratio of oil to water in the drain varies depending on the season. This is because the amount of oil in the drain is constant regardless of the season, and the amount of water changes in accordance with the humidity in the atmosphere.

Therefore, it is preferable to determine the ratio of oil to water in the drain from the humidity in the atmosphere and to limit the amount of power in accordance with the amount of oil. That is, if the parameter of the characteristic curve in FIG. 4 is the amount of oil, and if the amount of oil is low, an excessive amount of current is applied to generate a large amount of gas, there is only a small amount of oil to float with the generated gas. Therefore, the current can be limited in accordance with the amount of oil and the electrode can be prevented from dissolving to perform appropriate drain purification. If the current is limited in accordance with the amount of processing to be sent by the pump 7, more appropriate drain purification can be obtained.

The float switch is provided in the tank 3 to detect that the drain discharge amount is very small, and the drain purification is interrupted. When a certain amount of drain has accumulated, the float switch is activated and the control device 13 performs the purification process. It is good to restart.

[0027]

As described above, according to the present invention,
Regardless of the throughput, a stable high separation performance of oil and water can be obtained at low cost and without any trouble.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a drain purification device according to the present invention.

FIG. 2 is a diagram showing a relationship between a drain (content) amount and an electric conductivity in a fixed amount of a treatment liquid.

FIG. 3 is a diagram showing a relationship between electric conductivity in a treatment liquid and a control current (electric energy) required for oil-water separation.

4 is a diagram showing a relationship between a supply amount of a processing liquid to the electrolytic cell in FIG. 1 and a required amount of electricity for drain purification.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Compressor 2 ... Flow meter 3,4 ... Tank 5 ... Electromagnetic (control) valve 6 ... Sensor 7 ... Pump 8 ... Electrolysis tank 9 ... Power supply 10 ... Current control device 11 ... Specific gravity difference separation tank 12 ... Filter unit 13 ... Control device 14: Motor driver A, K: Electrode Ex: Drain outlet S: Scum

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masao Anzai 1007 Kamigo, Ebina-shi, Kanagawa Prefecture Within Hitachi Techno Engineering Co., Ltd. (72) Inventor Kenichi Takahashi 5-2-2 Koyodai, Ryugasaki-shi, Ibaraki Pref. Hitachi Techno Engineering Co., Ltd. Development Research Laboratory F-term (reference) EB40 ED12 FA04 FA06 FA13 GA02 GA06 GA12 GC02 GC06 GC12

Claims (4)

[Claims] In a drain purification method for separating oil and water by demulsifying, aggregating and floating oil in water by electrolysis in an electrolysis tank, an electrolyte is added to the drain while detecting electric conductivity. A drain purification method, comprising: supplying a treatment liquid having a desired electric conductivity by supplying a solution to an electrolysis tank, and applying electric power corresponding to the supply amount to an electrode of the electrolysis tank. 2. The method according to claim 1, wherein the electrolyte solution for conditioning electric conductivity of the drain is tap water. 3. A drain purifying device for separating oil and water by demulsifying, aggregating, and floating oil components suspended in water by electrolysis in an electrolysis tank, wherein a drain and an electrolyte solution are supplied. A control valve for controlling the amount of the electrolyte solution supplied to the tank, and adjusting the opening of the control valve in accordance with the electric conductivity detected by the detecting means to obtain the electric conductivity in the tank. Control means for maintaining the drain electrode and the electrolyte solution in the tank, and applying power to the electrodes of the electrolysis tank according to the supply amount of the processing liquid having the desired electric conductivity to the electrolysis tank. A drain purifying device comprising power supply means. 4. The apparatus according to claim 3, further comprising means for detecting a supply amount of the drain to the tank, and a supply amount of the processing liquid from the tank to the electrolysis tank according to the detection result. A drain purifying device, comprising: means for controlling pressure.