JP3782363B2 - Oil water separation method and apparatus for drainage drainage - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a system for separating the drain of a compressor containing charged oil particles into treated water that can be discharged into oil water, and in particular, a method for removing the charge of oil particles without discharging excess sludge. About.
[0002]
[Prior art]
Drain water is constantly discharged from compressors used in factories and the like through a drain trap. Since drain water contains oil, it is necessary to provide an oil / water separator in the drain pipe to separate the oil and improve the water quality to a certain level that meets environmental standards before discharging. In general, as a method of oil-water separation, floating separation by specific gravity difference, coagulation adding a small amount of ions to a hydrophobic colloid, aggregation (collection) by fine bubbles, adsorption by activated carbon or an adsorbent are known.
[0003]
The drain water discharged from the compressor contains fine oil particles and usually has both simple oil particles and charged oil particles. Simple oil particles change relatively easily into stable and coarse oil particles, and float on the surface of the reservoir so that they can be easily separated by specific gravity separation / adsorption separation, etc. Then, they repel each other due to negative charges and are difficult to aggregate as fine particles, and form a stable hydrophilic colloid solution, so that separation with an adsorbent or the like is difficult. For example, a drain discharged from a high-pressure compressor or a reciprocating compressor has a high ratio of such charged oil particles because it is operated at a high temperature and a high pressure. Therefore, in order to remove the electric charge of the oil particles, a method of removing the electric charge of the oil particles with a metal cation using an electrolytic method is used.
[0004]
The invention described in Japanese Patent Application Laid-Open No. 11-114304 discloses an oil-water separator in which a floating oil separation tank, an electrolytic tank, and an adsorption tank are connected in series, and a pressurized air supply means is connected to the adsorption tank. . The oil mixed in water is agglomerated and separated in an electrolytic cell and adsorbed while stirring with air in an adsorption cell.
[0005]
The invention described in the specification of Japanese Patent No. 2691119 is a hermetically pressurized oil-water separator by an electrolysis method provided with a separation tank, an electrolytic tank, and a floating layer, and an air (bubble) dissolver and a reduced pressure between the previous separation tank and the electrolytic tank. And a valve. In the present invention, the oil is agglomerated and adsorbed on sludge generated by the electrolytic treatment, and flotation is promoted and separated by bubbles.
[0006]
[Problems to be Solved by the Invention]
In all conventional oil-water separation methods using electrolytic separation means, flocs such as aluminum hydroxide Al (OH) ₃ are produced by eluting excess metal ions from the electrode, and this is recovered by gravity separation or adsorption separation. However, the Al (OH) ₃ floc to be separated must be treated as industrial waste, which is costly and requires much maintenance. In addition, when the amount of metal ions used is large, the positive electrode is consumed quickly, and the life of the electrode is shortened. Furthermore, extra power is consumed.
[0007]
An object of the present invention is to provide a method for removing oil particles, which suppresses generation of flocs, which are industrial wastes, and saves power consumption at a low maintenance cost in a method for treating drain water containing charged oil particles. With the goal.
[0008]
[Means for Solving the Problems]
According to the first aspect of the present invention, drain water is received and stored in a pretreatment tank, and water in the pretreatment tank is introduced into an electrolytic tank equipped with an electrode capable of supplying metal ions by a predetermined amount for electrolytic treatment. In the oil / water separation method for drainage drainage, in which the negative charge of the particles is removed to facilitate aggregation and then collected in the post-treatment tank, an air blowing tank is further provided in the subsequent stage of the electrolytic tank to aggregate the oil particles with bubbles, and The above-mentioned problem is solved by a drain water drainage oil / water separation method characterized in that the electrode current is automatically cut off after a certain period of time required to remove the charged oil particles from the feed.
[0009]
The invention according to claim 2 is capable of supplying metal ions, a pretreatment tank for storing drain water, a drain feeding means for feeding the drain water in the pretreatment tank downstream by a certain amount according to the drain water level, and Electrolytic tank with electrodes, air blowing tank for agglomerating oil particles with bubbles, post-treatment tank for adsorbing oil particles with adsorbent, and draining means for removing charged oil particles after operation The above-mentioned problem is solved by an oil-water separator for drainage drainage, characterized by having a control means for automatically stopping energization of the electrodes after a certain time required.
[0010]
The static eliminator of the present invention has a pretreatment tank that once receives and stores drain water discharged from a compressor through a drain trap. The pretreatment tank releases the compressed air contained in the drain water into the atmosphere, and adjusts the pressure of the drain water sent to the subsequent stage. Moreover, it is preferable to have the function to process the oil component contained as coarse oil particles from the beginning by adsorption or gravity separation.
[0011]
The drain water stored in the lower part of the pretreatment tank is fed into the electrolytic cell by drain feeding means that operates according to the water level. The drain feeding means has a level switch for detecting an increase in the water level and is connected to the compressed air supply means, and feeds a predetermined amount of drain water to the drain inlet of the electrolytic cell every time the drain reaches a certain water level. It is preferable that the structure in the electrolytic cell is a detour-type flow path having a constant wraparound so that the drain water fed from the drain feed means does not immediately flow out of the outlet. The electrolytic cell has an anode and a cathode, and an elution metal electrode having a large negative charge neutralizing ability such as aluminum or copper is used for the anode. The cathode is made of a stable material such as stainless steel, and an electrolytic cell container can be substituted. The power source of the electrode is controlled by the control means.
[0012]
While drain water drawn into the electrolysis site in the container moves between the electrodes, the metal ions eluted from the positive electrode attract the surrounding negatively charged oil particles by electric attraction and remove the negatively charged energy of the oil particles. To do. The oil particles from which the charge has been removed become hydrophobic and lose their repulsive force and gradually coagulate. To remove the negative charge of oil particles with metal ions, the higher the ionic value, the more effective. For example, Al is about 500 times less than the same amount of Na and about 8 times more negative charge removal than Cu. Therefore, it is most preferable to use an aluminum electrode for the anode because it exhibits a large negative charge removal effect and the electrode also lasts longer. The drain water containing simple oil particles from which electric charges have been removed is sent to a gravity separation tank or adsorption tank at a subsequent stage, and the oil is removed to become treated water that can be discharged.
[0013]
In the conventional method, after removing the negative charge of the oil particles, the electrode is further energized to deposit metal ions, and the flocs containing the oil particles are generated by utilizing the cohesive force of the metal ions, and the gravity separation or the like is used. However, the present invention is characterized in that the present invention is energized to the extent that the minimum metal ions required for removing the negative charge of the oil particles are eluted, and the oil particles are aggregated and separated in a subsequent adsorption tank or the like. There is.
[0014]
According to an experiment using an aluminum electrode, almost no floc of Al (OH) ₃ is generated until the charge removal of oil particles is completed, and Al ³⁺ ions eluted after that mainly form flocs. I understood it. Therefore, if the electrolysis is suppressed to the minimum necessary for the charge removal of the oil particles, generation of floc can be suppressed. In the first and second aspects of the invention, in order to prevent the excessive supply of metal ions, the power source control means energizes only for the time required for charge removal for one drain feed, and then automatically supplies power. To block.
[0015]
As a method for preventing the excessive supply of metal ions, a method of controlling the voltage in addition to controlling the energization time of the electrode can be considered. According to the invention of claim 3, drain water is received and stored in a pretreatment tank, the water of the pretreatment tank is introduced into an electrolytic tank equipped with an electrode capable of supplying metal ions, and subjected to electrolytic treatment, and the negative charge of oil particles In the oil-water separation method for drainage drainage, which is collected in a post-treatment tank after being removed and easily aggregated, an air blowing tank is further provided at the subsequent stage of the electrolytic tank to aggregate oil particles with bubbles, and the voltage between the electrodes The above-mentioned problem is solved by a method for separating oil from drainage drainage, which is characterized by maintaining the voltage below a certain voltage required for the charge removal of drain oil particles.
[0016]
According to a fourth aspect of the present invention, there is provided a pretreatment tank for storing drain water, drain feed means for feeding the drain water in the pretreatment tank to the downstream by a certain amount according to the drain water level, and an electrode capable of supplying metal ions. An electrolytic bath having an air bubble, an air blowing bath for agglomerating oil particles with bubbles, a post-treatment bath for adsorbing oil particles with an adsorbent, and a voltage between the electrodes to be equal to or lower than a predetermined voltage required for the charge removal of drain oil particles. The above-mentioned problem is solved by an oil / water separator for drainage drainage characterized by having a control means for maintaining.
[0017]
According to the third and fourth aspects of the present invention, the control means increases or decreases the voltage of the electrode in proportion to the drain feed amount indicated by the number of operations of the drain pumping unit. Compared with the method of claim 1, it has an advantage that it can easily cope with a case where the amount of drainage is large.
[0018]
The invention described in claims 5 and 6 supplies a pretreatment tank for storing drain water, a drain feeding means for feeding the drain water in the pretreatment tank to the downstream by a certain amount according to the drain water level, and supplying metal ions. An electrolyzer having a possible electrode, a water quality sensor provided downstream of the electrolyzer , an air blowing tank for agglomerating oil particles with bubbles, a post-treatment tank for adsorbing oil particles with an adsorbent, and a water quality sensor The above problem is solved by an oil / water separator for drainage drainage, characterized by having a control means for stopping the power supply of the electrode or adjusting the voltage according to the water quality. As the water quality sensor, for example, an electrical conductivity sensor provided at the outlet pipe of the electrolytic tank, a translucency sensor provided at the outlet of the adsorption tank, or the like can be used. When these sensors show a decrease in water quality, increasing the voltage of the electrode can prevent the deterioration of the treated water quality, and conversely preventing excessive electrolysis if the power is cut off when the water quality exceeds a certain level. In addition, the occurrence of flocks can be prevented and power can be saved.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. In FIG. 1, 1 is a pretreatment tank, 2 is a drain feeding means, 3 is an electrolytic tank, 4 is an air blowing tank, 5 is a primary adsorption tank, 6 is a secondary adsorption tank, and 7 is a control means. In this embodiment, the blowing of compressed air and the adsorption by the adsorbent are used in combination for the treatment after the charge removal of the oil particles.
[0020]
The pretreatment tank 1 of the present embodiment not only stores drain water, but also releases compressed air discharged from the compressor together with the drain water into the atmosphere, and adsorbs oil components originally contained as coarse oil particles in the drain water. It has the function to process by. The pretreatment tank 1 is formed of a cylindrical container having a drain inlet 101 and a drain outlet 102 on the bottom surface, and the drain inlet 101 is connected to a drain trap of a compressed air pipe (not shown). A shaft 103 communicating with the drain inlet 101 is provided, and an oil adsorbent 104 suitable for rough processing is filled around the shaft 103. Drain water is ejected from a fine ejection port 105 provided on the side surface of the shaft 102, and the inside of the oil adsorbent 103 is caused to flow down. Coarse oil particles that are likely to be adsorbed while drain water flows down are coarsely processed, and excess pressure air is discharged from the upper opening 106. A buffer 107 for preventing the drain water from scattering is provided at the opening.
[0021]
The drain pipe connected to the drain outlet 102 of the pretreatment tank 1 is provided with a drain feeding means 2 via a pair of check valves V1, V2. The drain branch pipe branched from between the check valves V1 and V2 extends upward and is connected to the bottom of the drain chamber 202 of the drain pumping unit 201 installed at the middle height of the pretreatment tank 1. Inside the drain chamber 202 is provided a level switch 203 that detects the rise of the drain liquid level and outputs it to the control means 7. The height of the water surface detected by the level switch 203 in the drain chamber 202 corresponds to the appropriate drain water height in the pretreatment tank 1. In addition, a compressed air pipe that is connected to a compressed air main pipe through an electromagnetic valve E1 and a pressure control valve R is connected to the upper portion of the drain chamber 202. The downstream pipe of the drain is connected to the upper part of the electrolytic cell through the check valve V2 and the rising part.
[0022]
The electrolytic cell 3 is composed of a substantially cylindrical stainless steel container provided with a drain inlet 301 and a drain outlet 302 on the upper side, and an aluminum cylindrical electrode 303 is accommodated therein (FIG. 2). A distal end portion of a drain pipe 305 extending inward from the drain inlet 301 is coupled to an upper portion of the electrode 303 via a rubber insulating portion 304. An opening through which drain water can enter and exit is provided at the bottom of the electrode 303, and the drain water descending from the inside of the electrode 303 flows out of the opening and then travels around the bottom of the container to rise again outside the electrode 303. Yes. In addition, a shaft portion 306 made of a conductor whose periphery is insulated passes through the top surface of the container and the drain pipe 305 and is fixed to the bottom portion of the electrode 303. Terminals provided on the upper portion of the shaft portion 306 and the container are connected to a power supply via a power supply control portion 307, respectively. The power supply control unit 307 is controlled by the control means 7.
[0023]
In the present embodiment, an electrical conductivity sensor S <b> 1 is provided at the outlet pipe of the air blowing tank 4. The electrical conductivity sensor S1 has at least two electrodes, a power supply circuit, and current measuring means, and detects the increase or decrease in electrical conductivity by measuring the magnitude of the current flowing in the drain water, and outputs it to the control means 7 To do. As another example, a drain transmissivity sensor (not shown) can be provided at the outlet of the primary adsorption tank 5 or the secondary adsorption tank 6. The drain transmissivity sensor is a device similar to that described in Japanese Patent Application Laid-Open No. 2001-9205, and includes a light emitting element, a light receiving element, a power supply circuit, and a current amount detecting means installed in the drain pipe. By measuring the amount of light that has passed through the drain water, an increase or decrease in the translucency or turbidity of the drain water is detected and output to the control means 7.
[0024]
The drain water discharged by the operation of the compressor flows down inside the pretreatment tank 1 and gradually accumulates at the bottom of the container, and the water level rises. As a result, when the level switch 203 in the pressure feeding unit 201 detects a rise in the water level, the electromagnetic valve E1 opens to supply compressed air to the pressure feeding unit 201 for a certain period of time, and to drain water drawn into the drain chamber 202 and the drain branch pipe. Discharge. Since the check valves V <b> 1 and V <b> 2 are provided before and after the branch portion of the drain main pipe, the discharged drain water is sent to the electrolytic cell 3. Every time the drain water in the pretreatment tank 1 reaches a certain amount, about 100 cc of drain water is fed from the pretreatment tank 1 to the electrolytic cell 3 (tact treatment). When a compressor with an output of 75 KW is operated under standard weather conditions, the maximum amount of drainage that can be pumped is about 18 l / hr (average 8 l / hr), so several times per minute (100 cc each) can be pumped. Is called.
[0025]
The drain water in the electrolytic cell 3 gradually proceeds through the flow path in the electrolytic cell during several tact treatments by the pumping unit 2. When a DC voltage (10 V) is applied between the shaft portion 306 and the container by the control means 7 to be described later, a potential difference is generated between the electrode 303 and the outer periphery of the container, and Al ³⁺ ions eluted from the positive electrode are The negatively charged oil particles are attracted by the attractive force to remove the negative charges of the oil particles. The drain water is removed by electrification while rising between the sides of the aluminum electrode 303 container, and the repulsive force between the oil particles is removed, and the drain water is easily aggregated and flows out from the drain outlet 302 sequentially. In this way, the drain in the electrolytic cell is once removed from the charge while bypassing the bottom of the container, so that the untreated drain that has flowed from the drain inlet 301 does not flow out of the drain outlet 302 as it is.
[0026]
For example, when 100 cc of drain water having a standard oil concentration of 200 mg / l is newly introduced into an electrolytic cell having a volume of 250 cc having an aluminum electrode and DC 10 V is applied to the electrode to measure the quality of the treated water, the negative charge of the oil particles The energization time required for removal was about 3 minutes in the case of the aluminum electrode. Therefore, if the energization time is set to about 3 minutes for one operation of the pressure feeding unit, the charge of the oil particles can be removed with almost no floc formed. When a copper electrode is used as the electrode, the energization time required for removing the negative charge of the oil particles is about 8 minutes, so the energization is stopped after 8 minutes.
[0027]
In this embodiment, the control means 7 monitors the output of the electrical conductivity sensor S1, and stops the energization even within the energization time when the electrical conductivity increased by the drain water feeding becomes below a certain value. To prevent flocs due to excessive electrolysis.
[0028]
The drain water from which the electric charge of the oil particles has been removed in the electrolytic tank is sent to the air blowing tank 4, the primary adsorption tank 5 and the secondary adsorption tank 6 in the subsequent stage, and the oil particles that have become easy to aggregate with each other are aggregated with bubbles. It is adsorbed and separated by a post-adsorbent, and discharged as treated water with an oil concentration of 5 mg / l or less that can be discharged. These treatments are described in detail in the same application “Oil-water separation method and apparatus” on the same day of the present applicant.
[0029]
【The invention's effect】
The electrification removal device in the drainage oil-water separator of the present invention suppresses the generation of sludge, which is industrial waste, by suppressing the elution of metal ions, so that waste treatment is not required and the life of the elution electrode is increased. Therefore, the maintenance cost of the oil / water separator can be reduced. By treating the drain water pretreated with this apparatus with an adsorbent or the like, the capacity of the adsorbent can be maximized and high-quality treated water can be obtained.
[0030]
If an optimal control method is used in accordance with the operating environment such as a compressor, the amount of electrolysis is automatically adjusted even if the amount of drain or oil concentration fluctuates.
[Brief description of the drawings]
FIG. 1 shows an example of an oil-water separator using a charge removing device according to the present invention.
2 is a longitudinal sectional view of the electrolytic cell in FIG. 1. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pretreatment tank 101 Drain inlet 102 Drain outlet 103 Shaft 104 Oil adsorbent 105 Jet outlet 106 Opening 107 Buffer 2 Drain feeding means 201 Drain pressure feeding unit 202 Drain chamber 203 Level switch 3 Electrolyzer 301 Drain inlet 302 Drain outlet 303 Electrode 304 Insulation Section 305 Drain pipe 306 Shaft section 4 Air blowing tank 5 Primary adsorption tank 6 Secondary adsorption tank 7 Control means

Claims (6)

Drain water is received and stored in the pretreatment tank, and the water in the pretreatment tank is introduced into the electrolytic tank equipped with electrodes capable of supplying metal ions by a predetermined amount to perform electrolytic treatment, removing the negative charge of the oil particles and agglomerating In the oil-water separation method for drainage drainage to be adsorbed by the adsorbent in the post-treatment tank, an air blowing tank is further provided at the subsequent stage of the electrolytic tank to aggregate the oil particles with bubbles, and the oil particles are fed from the drain feed. An oil-water separation method for drainage drainage, which automatically stops energization of an electrode after a predetermined time required for charge removal. A pretreatment tank for storing drain water, a drain feeding means for feeding the drain water in the pretreatment tank downstream by a certain amount according to the drain water level, an electrolytic tank having an electrode capable of supplying metal ions, and an oil An air blowing tank that agglomerates particles with bubbles, a post-treatment tank that adsorbs oil particles with an adsorbent, and a drain feeding means that automatically operates to the electrode after a certain time required to remove the charged oil particles. An oil-water separator for drainage drainage, characterized by having control means for stopping energization of the drainage. Drain water is received and stored in the pretreatment tank, and the water in the pretreatment tank is introduced into an electrolytic tank equipped with an electrode capable of supplying metal ions and electrolyzed to remove the negative charge of the oil particles and facilitate aggregation. In the oil-water separation method of drainage drained to be adsorbed by the adsorbent in the post-treatment tank, an air blowing tank is further provided at the subsequent stage of the electrolytic tank to aggregate oil particles with bubbles, and the voltage between the electrodes is set to drain oil particles. An oil-water separation method for drainage drainage, characterized in that the voltage is maintained at a level required for the charge removal. A pretreatment tank for storing drain water, a drain feeding means for feeding the drain water in the pretreatment tank downstream by a certain amount according to the drain water level, an electrolytic tank having an electrode capable of supplying metal ions, and an oil An air blowing tank for agglomerating the particles with bubbles, a post-treatment tank for adsorbing the oil particles with the adsorbent, and a control means for maintaining the voltage between the electrodes at a voltage required to remove the oil particles from the drain. An oil / water separator for drainage drainage. A pretreatment tank for storing drain water, a drain feeding means for feeding the drain water in the pretreatment tank downstream by a certain amount according to the drain water level, an electrolytic tank having an electrode capable of supplying metal ions, and electrolysis When a water quality sensor provided downstream of the tank, an air blowing tank for agglomerating oil particles with bubbles, a post-treatment tank for adsorbing oil particles with an adsorbent, and the water quality indicated by the water quality sensor are above a certain value A drainage oil-water separator having a control means for automatically stopping energization of the electrode. A pretreatment tank for storing drain water, a drain feeding means for feeding the drain water in the pretreatment tank downstream by a certain amount according to the drain water level, an electrolytic tank having an electrode capable of supplying metal ions, and electrolysis A water quality sensor provided downstream of the tank, an air blowing tank for agglomerating oil particles with bubbles, a post-treatment tank for adsorbing oil particles with an adsorbent, and automatically when the water quality indicated by the water quality sensor becomes high The drainage oil-water separator has a control means for reducing the voltage of the electrode.

Images