JP2000288439A - Recovering method of waste solvent and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely prevent the clogging of a drain pipe by effectively cleaning and removing paint soiling stuck on the inside surface of an intermediate tank storing a waste solvent discharged from a coating machine or a coating material feed line or on the inside wall of the drain pipe with the waste solvent. SOLUTION: Before the waste solvent 3A in the intermediate tank 1 is recovered to a recovering tank 5, the waste solvent 3B in the recovering tank 5 is refluxed to the intermediate tank 1 to clean and remove the paint soiling stuck to the inside of the drain pipe 7 of the intermediate tank 1 with the refluxed waste solvent and the stored quantity of the waste solvent 3A in the intermediate tank 1 is increased to dissolve and remove the paint soiling stuck to the inside surface of the intermediate tank 1.

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 collecting a waste liquid solvent discharged from a coating machine or a paint supply system thereof.

[0002]

2. Description of the Related Art In an automobile painting factory that uses a large amount of an organic solvent such as a thinner, a waste spray paint discharged from a painting machine and a solvent for diluting the paint are mixed to prevent pollution and save resources. Multiple relay tanks for temporarily storing waste liquid solvent and waste liquid solvent that is a mixture of cleaning solvent and residual paint discharged from the coating machine or its paint supply system when the color of the paint is changed or after the paint finishes are installed on top machines and side machines. It is installed at various places such as automatic painting zone by machine, robot painting zone, hand-blown painting zone, etc., and the waste liquid solvent stored in each relay tank is collectively collected in the collection tank through the collection pipe by the relay pump, The wastewater is transferred from the collection tank to a large-capacity wastewater tank installed outdoors and delivered to a wastewater treatment company.

A relay tank for storing a waste liquid solvent has a capacity of about 10 to 30 liters, and has an inner diameter of 1 to 30 liters at the bottom thereof.
A narrow drain pipe of about 0 mm is provided, and the drain pipe is connected to a collection pipe for transferring the waste liquid solvent in each relay tank to the collection tank by a relay pump.

[0004]

By the way, the paint components in the waste liquid solvent discharged from the coating machine and its paint supply system are:
Since it is dissolved in the solvent, it does not easily adhere to the inner surface of the relay tank, the inner wall of the drain pipe, the inner wall of the recovery pipe, etc., but it takes about one hour to start transferring the waste liquid solvent in each relay tank to the recovery tank. There is an interval, and during the interval, since the waste liquid solvent does not flow at all inside the drain pipe, a paint stain is generated on the inner wall of the drain pipe, and the paint stain is gradually reduced with time. It could grow and cause the narrow drain tube to clog.

[0005] For this reason, the applicant periodically pours almost completely unused clean solvent from above each relay tank into the tank, and uses the relay pump to collect the clean solvent from the relay tank from the relay tank. To remove paint stains attached to the inner surface of the relay tank, the inner wall of the drain pipe, and the like.

However, in order to wash and remove paint stains attached to the inner surface of the relay tank and the inner wall of the drain pipe,
Consuming large amounts of clean solvents is against resource conservation,
Simply by flowing the clean solvent in one direction from the relay tank to the recovery tank, paint stains adhered to the inner wall of the drain pipe could not be effectively washed and removed.

Accordingly, the present invention effectively eliminates paint stains adhering to the inner surface of the relay tank and the inner wall of the drain pipe by using only the waste solvent recovered from the relay tank to the recovery tank without using any clean solvent. A technical issue is to make it possible to remove by washing.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a method of temporarily storing waste liquid solvent discharged from a coating machine or its paint supply system in a plurality of relay tanks installed at various locations, In the waste liquid solvent recovery method of recovering the waste liquid solvent stored in the relay tank from the drain pipe of each relay tank to the recovery tank through the recovery pipe, before recovering the waste liquid solvent stored in the relay tank to the recovery tank, The waste liquid solvent in the recovery tank is caused to flow back to the recovery pipe by a predetermined amount, and the waste liquid solvent flowing back in the recovery pipe is caused to flow into the tank through the drain pipe of the relay tank, and the allowable amount of the relay tank is reduced. The storage amount of the waste liquid solvent in the tank is increased within a range not exceeding the limit.

According to the present invention, before the waste solvent stored in the relay tank is collected in the recovery tank, the waste solvent flows backward in the drain pipe of the relay tank, and the drain solvent is drained by the backwashing action of the waste solvent. Paint stains adhering to the inner wall of the pipe are effectively removed, and the amount of waste liquid solvent stored in the relay tank increases, and the paint stains adhering to the inner surface of the relay tank are dispersed by the dissolving action of the waste solvent. Removed without.

When the waste liquid solvent stored in the relay tank is collected in the recovery tank, a large amount of waste liquid solvent flows out of the relay tank. Therefore, the paint stain adhered to the inner wall of the drain pipe by the waste liquid solvent is washed. The effect of removing increases.

[0011]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a flow sheet diagram showing a waste liquid solvent recovery device, and FIG. 2 is a flowchart showing the operation of the recovery device.

In the drawing, reference numeral 1 denotes a relay tank for receiving a waste liquid solvent discharged from the coating machine 2 or its paint supply system by a hopper 4 and storing the waste liquid solvent at various points in a coating zone;
The collection tank 6 collectively collects the waste liquid solvent 3A stored in the storage tank 5, and 6 is a waste liquid tank that transfers the waste liquid solvent 3B collected in the collection tank 5.

A drain pipe 7 of each relay tank 1 is connected to a rotary pump 8 serving as a relay pump for discharging the waste liquid solvent 3A in the tank.
And is connected to a collection pipe 9 for transferring to the collection tank 5. Further, each relay tank 1 is provided with a liquid level meter 10 for detecting the storage amount of the waste liquid solvent 3A in each tank.

Reference numeral 11 denotes a control device for switching the rotation of the rotary pump 8 in the forward and reverse directions based on the detection signal of the liquid level meter 10 and for opening and closing the drain valve 12 provided in the drain pipe 7 of each relay tank 1. And the control device 11
Opens the drain valve 12 provided in the drain pipe 7 of the relay tank 1 when the storage amount of the waste liquid solvent 3A in the relay tank 1 detected by the liquid level meter 10 reaches the upper limit set value. At the same time, the rotary pump 8 is driven to rotate in the reverse direction so that the waste liquid solvent 3B in the recovery tank 5 flows back to the recovery pipe 9 by a certain amount.

In order to prevent a fire caused by ignition of the solvent, the liquid level gauge 10 detects a float 13 floating on the liquid surface of the waste liquid solvent 3A stored in the relay tank 1 and a detection signal based on the displacement of the float 13. A float type liquid level meter comprising an air limit switch 14 for outputting an air signal is used. The air limit switch 14 determines that the storage amount of the waste liquid solvent 3A is, for example, about 60% of the tank capacity of the relay tank 1. Is turned on when an upper limit set value corresponding to is increased and a detection signal by air is output, and is turned off when the stored amount decreases to a lower limit set value corresponding to about 30% of the tank capacity. I have.

As the relay pump, an air-driven rotary pump driven by an air motor 15 is used, and as the drain valve 12, an air-driven valve that is opened and closed by air pressure is used.

The control device 11 controls the liquid level meter 1
0 signal air or the air motor 15 of the rotary pump 8
An air pressure control panel having a control circuit such as a pump driving air for rotating the pump in the forward and reverse directions and a valve driving air for opening and closing the drain valve 12 is used.

Reference numeral 16 denotes an air supply source of the control device 11, and reference numeral 17 denotes a waste liquid recovery pump for transferring the waste liquid solvent 3B recovered in the recovery tank 5 to the waste liquid tank 6 installed outdoors.

The above is the configuration of the recovery apparatus shown in FIG. 1. Next, the operation will be described with reference to the flowchart of FIG. The control device 11 determines whether or not the air limit switch 14 of the liquid level meter 10 is turned on in a step during the operation of the recovery device, and determines the storage amount of the waste liquid solvent 3A in the relay tank 1 as the tank capacity. When the upper limit value corresponding to about 60% is reached and the air limit switch 14 is turned on, an air timer for setting a fixed time of about several minutes in a step is turned on. When the air timer is turned on, a step is performed. At the same time as supplying the pump driving air for reversely driving the rotary pump 8 to the air motor 15, the drain valve 1 of the relay tank 1 in which the air limit switch 14 of the liquid level meter 10 is turned on.
The supply of valve driving air for opening the valve 2 is started.

Thus, the waste liquid solvent 3 in the recovery tank 5
B flows back into the recovery pipe 9, and the waste liquid solvent flowing back in the recovery pipe 9 flows into the relay tank 1 through the drain pipe 7 with the drain valve 12 opened, and the drain pipe 7
The inside of the pipe is backwashed to effectively remove paint stains adhering to its inner wall, and the amount of waste liquid solvent 3A stored in the relay tank 1 is increased, so that paint stains adhering to the inner surface of the tank are evenly removed. Dissolution and removal.

The air timer is turned off as long as the amount of the waste liquid solvent 3A stored in the relay tank 1 does not exceed the allowable amount of the relay tank 1. When the air timer is turned off, the air motor 15 Then, the supply of pump driving air for driving the rotary pump 8 to rotate forward is started.

As a result, the backflow of the waste liquid solvent 3B from the recovery tank 5 to the recovery pipe 9 is stopped, and the increase in the storage amount of the waste liquid solvent 3A in the relay tank 1 is stopped. Waste liquid solvent 3
A flows out of the drain pipe 7 and is transferred to the recovery tank 5 through the recovery pipe 9, and the waste liquid solvent 3A flowing out in large quantities
Then, the inside of the drain pipe 7 is washed.

When the storage amount of the waste liquid solvent 3A in the relay tank 1 decreases to a lower limit set value corresponding to about 30% of the tank capacity and the air limit switch 14 is turned off, the air motor 15 The supply of the pump driving air is stopped to stop the rotation of the rotary pump 8 and the drain valve 1 provided in the drain pipe 7 is stopped.
2 is closed, and the recovery of the waste liquid solvent 3A from the relay tank 1 is stopped.

Note that even if the air limit switch 14 of the liquid level gauge 10 of the other relay tank 1 is turned on during the execution of the steps 1 to 3, the control device 11 continues to operate the air limit switch until the operation is completed. The output circuit of the detection signal from 14 is closed, and after the operation is completed, the output circuit is opened.

As described above, before the waste liquid solvent 3A stored in the relay tank 1 is recovered in the recovery tank 5, a certain amount of the waste liquid solvent 3B in the recovery tank 5 is caused to flow back to the recovery pipe 9,
The waste liquid solvent flowing backward in the recovery pipe 9 flows into the relay tank 1 through the drain pipe 7 to increase the storage amount of the waste liquid solvent 3A in the tank within a range not exceeding the allowable amount of the relay tank 1. As a result, paint stain adhering to the inner wall of the drain pipe 7 is removed from the collection tank 5 side by the relay tank 1.
The waste liquid solvent flowing back to the side is effectively washed and removed, thereby reliably preventing the drain tube 7 from being clogged, and also dissolving and removing paint stains attached to the inner surface of the relay tank 1 uniformly.

When about 30 minutes have passed since the collection of the waste solvent from the relay tank 1 was stopped, the collection tank 5
The paint component in the waste liquid solvent 3B collected in the tank 5 sinks below the tank, and a supernatant having a small paint content is generated. Therefore, if the supernatant of the waste liquid solvent 3B is caused to flow back to the collection pipe 9, The backwashing effect of the drain tube 7 is further enhanced.

At the start of the operation of the recovery device and before the operation is stopped, the waste liquid solvent 3B in the recovery tank 5 is caused to flow back to the recovery pipe 9, so that the storage amount of the waste liquid solvent 3A in each relay tank 1 is increased simultaneously. After that, the waste liquid solvent 3A in each of the relay tanks 1 is collectively collected in the collection tank 5, so that the drain pipe 7 and the collection pipe of the relay tank 1 can be collected on holidays or breaks when the operation of the collection device stops. Paint stains generated on the inner wall of the pipe 9 are greatly reduced.

The waste liquid solvent 3B recovered in the recovery tank 5 is transferred to the waste liquid tank 6 by the waste liquid recovery pump 17, and the waste liquid solvent 3C stored in the waste liquid tank 6 is delivered to a waste liquid processing company.

[0029]

According to the present invention, paint dirt adhering to the inner surface of a relay tank storing the waste liquid solvent or the inner wall of its drain pipe can be effectively used using only the waste liquid solvent discharged from a coating machine or the like. In particular, there is an extremely excellent effect that the clogging of the drain tube can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is a flow sheet diagram showing a waste liquid solvent recovery device according to the present invention.

FIG. 2 is a flowchart showing the operation of the collection device.

[Explanation of symbols]

1 ... Relay tank 9 ... Recovery pipe 2 ... Coating machine 10 ... Level gauge 3A ... Waste liquid solvent 11 ... Control device 3B ··· Waste liquid solvent 12 ··· Drain valve 5 ··· Recovery tank 13 ··· Float 7 ··· Drain pipe 14 ··· Air limit switch 8 ··· .... Rotary pump 15 ... Air motor

Claims (4)

[Claims] 1. A waste liquid solvent discharged from a coating machine or a paint supply system thereof is temporarily stored in a plurality of relay tanks installed at various locations, and the waste liquid solvent stored in the relay tanks is drained from drain pipes of the respective relay tanks. In the method for collecting a waste liquid solvent collected in a collection tank through a collection pipe, the waste liquid solvent (3A) stored in the relay tank (1) is collected in the collection tank (5) before being collected in the collection tank (5). A certain amount of the waste liquid solvent (3B) flows back into the recovery pipe (9), and the waste liquid solvent flowing backward in the recovery pipe (9) flows through the drain pipe (7) of the relay tank (1) into the tank (1). ), And increasing the storage amount of the waste liquid solvent (3A) in the relay tank (1) within a range not exceeding the allowable amount of the relay tank (1). 2. The waste liquid solvent (3B) in the recovery tank (5), which flows back to the recovery pipe (9),
2. The method according to claim 1, wherein the supernatant is B). 3. A plurality of relay tanks for storing waste liquid solvents discharged from a coating machine or a paint supply system thereof at various locations, and a collection tank for collectively collecting the waste liquid solvents stored in the relay tanks, A drain pipe of each of the relay tanks is connected to a collection pipe for transferring the waste solvent in the relay tank to the collection tank by a relay pump. The liquid level meter (10) for detecting the storage amount of (3A) and the rotary pump (8) serving as the relay pump are switched in the forward and reverse directions based on the detection signal of the liquid level meter (10). And a control device (1) for opening and closing a drain valve (12) provided in a drain pipe (7) of each relay tank (1).
And a drain valve (3) provided in the drain pipe (7) of the relay tank (1) when the storage amount of the waste liquid solvent (3A) in the relay tank (1) reaches a set value. 12) is opened and the rotary pump (8) is driven to rotate in the reverse direction so that the waste liquid solvent (3B) in the recovery tank (5)
Is configured to flow back to the recovery pipe (9) by a predetermined amount. 4. A float (13) floating on the liquid surface of the waste liquid solvent (3A) in the relay tank (1) and a detection signal based on displacement of the float (13). A float type liquid level meter comprising an air limit switch (14) for outputting an air signal, the rotary pump (8) being an air-driven rotary pump driven by an air motor (15), and the drain valve ( 12) is an air-driven valve that is opened and closed by air pressure, and the control device (11) rotates the signal air of the liquid level gauge (10) and the air motor (15) in forward and reverse directions. 4. The collecting device according to claim 3, wherein the collecting device is an air pressure control panel having a control circuit for controlling a pump driving air and a valve driving air for opening and closing the drain valve (12).