JP2003126843A - Oil water separating system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide oil water separating system which is equipped with a mechanism in a vacuum chamber to detect a liquid level precisely without affected by the fluctuated liquid level caused by low temperature boiling and can control the operation. SOLUTION: The oil water separating system consists of a conventional vacuum chamber and a sub-tank whose liquid level equals to the vacuum chamber liquid level. This system obtains a liquid level by measuring the pressure change in the sub-tank when the vacuum chamber is separated from the sub-tank and a given amount of air is introduced in the sub-tank during vacuum distillation and feeds it back to operation control.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil / water separator for drain of compressed air or the like in an oil supply type compressor, and more particularly,
The present invention relates to a vacuum chamber type oil-water separation device that heats a drain in a vacuum state to boil at a low temperature and vaporizes and evaporates water in the drain by utilizing a difference in boiling points of oil and water.

[0002]

2. Description of the Related Art A refueling type compressor is a general compressor which is widely used in the industrial field where compressed air is used as a utility. Most of the compressors of this type are a screw type and a reciprocating type. In the case of the screw type, the purpose is to seal the gap between the two screw rotors that compress air, the purpose to cool the compression heat generated in the compression process,
A necessary amount of lubricating oil is supplied to the inside of the compressor for the purpose of lubricating the contact portion between the rotors. Further, in the case of the reciprocating compressor, lubricating oil is supplied to the inside of the cylinder for the purpose of lubricating the contact portion of the cylinder and piston for compressing air.

Compressed air produced by this type of compressor contains the aforementioned lubricating oil. Then, this compressed air is usually cooled to around room temperature and supplied to the air machine. For this reason, the water in the compressed air is condensed during the cooling process, and a drain containing oil is generated. This drain removes oil for environmental protection, and can be drained after reducing the oil concentration below the legally determined oil concentration standard value. As a drain oil / water separation technology, generally, oil removal by a filter, electrolysis, flotation, vacuum distillation method and the like are adopted.

Particularly, in Japanese Patent Laid-Open No. 11-343976, when a certain amount of drain is accumulated in the oil / water separation vacuum chamber, the oil / water inlet valve is closed, heating by the heater and operation of the vacuum pump are started, and the oil / water vacuum chamber is started. The inside becomes a superheated vacuum state. As a result, the water in the drain boils at a low temperature, is reduced to the atmosphere through the vacuum pump, and the condensed drain having a high oil concentration remains in the oil / water vacuum chamber. At this stage, the vacuum pump is stopped, the heater is turned off, the pressure equalizing valve and the oil discharge valve are opened, and the drain with the reduced oil concentration is discharged. After that, the oil discharge valve and the pressure equalizing valve are closed, the oil / water feeding valve is opened, and the oil / water separation is continuously performed by repeating the above-described operation.

[0005]

In the above-mentioned prior art, it is necessary to detect the liquid level in the vacuum chamber in order to automatically perform a series of operation controls. As a general method for detecting the liquid level, a float type level switch may be provided in the vacuum chamber, or the weight of the vacuum chamber may be measured by a weight sensor to convert the weight change into the liquid level. . These methods have the following problems. 1. Drain heated and boiled in a vacuum state causes bubbles of evaporation phenomenon in the liquid, grows and repeats bursting at the liquid level, and liquid level fluctuations are remarkable, so the liquid level is accurately detected with a float type level switch. I can't. 2. As described above, since the vacuum chamber vibrates due to the liquid level variation, the weight sensor cannot accurately detect the weight of the vacuum chamber.

From the above, it is difficult to detect the liquid surface height in the vacuum chamber by applying the general detection method in the prior art, and it is difficult to automate the operation of the oil-water separator by the vacuum distillation method. Is a challenge.

SUMMARY OF THE INVENTION An object of the present invention is to provide an oil / water separation device capable of accurately measuring the liquid level in the vacuum chamber and enabling automatic operation of oil / water separation.

[0008]

In order to achieve the above object, the present invention provides a sub-tank in which the liquid level is the same as the liquid level in the vacuum chamber, and the vacuum distillation work is performed. Inside, separate the vacuum chamber and sub tank,
The pressure change when a predetermined amount of air is introduced into the sub-tank is measured, and the liquid level height in the sub-tank is determined using the measured pressure change, and is used as the liquid level height in the vacuum chamber.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a schematic configuration of an embodiment of an oil / water separator according to the present invention.

This system is constructed as follows.
Drain containing an oil component generated in a compressor or the like (not shown) is stored in the drain tank 8. This drain tank 8
Drain accumulated in the pipe 21b and the solenoid valve E14
Then, it is sent to the vacuum chamber 1 through the pipe 21a. Also, the drain sent to the vacuum chamber 1 at the same time,
It is also sent to the sub tank 2 via the pipe 16a, the solenoid valve A10, and the pipe 16b.

A pipe 19 is connected to the upper portion of the vacuum tank 1, and the pipe 19 is used to bring the inside of the vacuum tank 1 into a vacuum state (reduced pressure state) or to return it to atmospheric pressure. Furthermore, the upper part of the vacuum tank 1 and the upper part of the sub tank 2 are connected via a pipe 17a, a solenoid valve B11, and a pipe 17b, and by opening the solenoid valve B11,
The pressures in the sub tank 2 and the vacuum tank 1 are set to be the same. Furthermore, on the outside of the lower part of the vacuum tank 1,
A heater 7 is provided.

A pressure sensor 9 is provided on the upper side of the sub-tank 2, and a pipe 18a for connecting to the constant volume air tank 3, a solenoid valve C12, and a pipe 18 are provided.
b and are provided. Further, a solenoid valve D13 is provided on the upper side of the metering air tank 3.

A solenoid valve F15 is provided at the end of the pipe 19 provided on the upper side of the vacuum tank 1 on the vacuum tank 1 side,
By opening the solenoid valve 15, the vacuum tank 1 and the sub tank 2 can be returned to the atmospheric pressure. Furthermore, the piping 19
A condenser 4 is provided on the other end side of the condenser 4, and a vacuum pump 6 is connected to the condenser 4 via a pipe 20. In addition,
The condenser 4 is provided with a cooling fan 5.

Next, the vacuum distillation process will be described.

When a main power switch (not shown) is turned on,
The cooling fan 5 and the vacuum pump 6 are driven, and the solenoid valve C1
2. The solenoid valve F15 is closed. Incidentally, another solenoid valve A10,
The solenoid valve B11 and the solenoid valve E14 are open. Therefore, the air in the vacuum chamber 1 and the sub tank 2 is released to the atmosphere through the pipe 19, the condenser 4, the pipe 20 and the vacuum pump 6. Therefore, the vacuum degree of the vacuum chamber 1 and the sub tank 2 gradually increases.

The drain (a) accumulated in the drain tank 8 is sucked into the vacuum chamber 1 and the sub tank 2 as the degree of vacuum increases. Then, by a command (signal) from a control panel (not shown), the solenoid valve E14 is closed at a preset time after the main power is turned on, and the heater 7 is energized.

In this state, the drain (b) is stored in the vacuum chamber 1 and the drain (c) is stored in the sub tank 2. In addition, the vacuum chamber 1 and the sub tank 2 are connected to the pipe 16
a, the solenoid valve A10, the pipe 16b, and the pipe 17a,
The solenoid valve B11 and the pipe 17b communicate with each other, and the drain (b) and the drain (c) have the same liquid level.

After the heater 7 is energized, the temperature of the drain (b) rises, and when the boiling point of water determined according to the vacuum degree of the vacuum chamber 1 is reached, evaporation of the water in the drain (b) starts.
The steam generated in the vacuum tank 1 enters the condenser 4 through the pipe 19, is cooled by the cooling fan 5, is reduced to water from the steam, and is then discharged through the vacuum pump 6 through the pipe 20. . When the drain (b) in the think tank 1 decreases, the drain (c) flows from the sub tank 2 into the vacuum tank 1 side. Therefore, the water content of the drain (b) and drain (c) is reduced by evaporation, and the oil content that does not evaporate due to low temperature boiling remains. When the liquid level drops by a predetermined amount, the solenoid valve E14 is opened by an instruction from a control panel (not shown),
The drain (a) of the drain tank 8 is sucked into the vacuum chamber 1 and the sub tank 2 again, and the above evaporation process is repeated.

Next, the liquid level control will be described. There are two possible methods for determining the liquid level. One method is to supply a fixed amount of air from the outside for a certain period of time and obtain it from the pressure change during that period. The other method is a method of obtaining from the pressure change due to communication with the metering container.

In the first method, the space volume is V, the initial pressure is P1, the final pressure is P2, and the supply air pressure is P.
3, supply air quantity Q, gas constant R, gas temperature T,
Let G be the weight of the gas. Also, the initial and final gas constants,
The change in temperature is small and negligible. From the equation of state of gas PV = GRT, the initial weight is G1 = (P1 × V) / (R × T) and the final weight is G2 = (P2 × V) / (R × T). Since it is equal to the quantity, G2-G1 = (P2-P1) * V / (R * T) = (P3 * Q) / (R * T)? V = (P3 * Q) / (P2-P1) ... ( 1) is required.

In the second method, the space volume is V1, the initial pressure of the space volume is P1, the volume of the fixed quantity container is V2, the initial pressure of the fixed quantity container is P2, and the ultimate pressure after the space volume and the fixed quantity container are communicated with each other. Is P3, and each symbol in the equation of state of gas is the same as the first term. Initial weight in space volume G1 = (P1 × V1) / (R ×
T) Initial weight in quantitative container G2 = (P2 × V2) / (R ×
T) Weight of fluid after communication G3 = P3 × (V1 + V2) /
(R × T) When V1 is calculated from G3 = G1 + G2, ∴V1 = (P2-P3) × V2 / (P3-P1) (2)

As described above, it is calculated by introducing measurable air into the container on a regular basis and measuring the pressure as the state change in the container. The space volume is constant at the time of measurement regardless of whether the liquid surface changes. Moreover, since it is not affected by vibration, it is possible to stably capture the state during measurement.

Here, a method for obtaining and controlling the liquid level by the second method will be described.

During normal operation, solenoid valve A10 and solenoid valve B11
The pipes 16a, 16b and the pipe 1
The liquid levels of the drain (b) of the vacuum chamber 1 and the drain (c) of the sub tank 2 are kept equal by the communication of 7a and 17b. The internal pressure of the sub tank 2 is equal to the internal pressure of the vacuum chamber 1 and is the vacuum pressure P1. In this state, a control panel (not shown) outputs a signal at preset time intervals to close the solenoid valves A10, B11 and D13 and open the solenoid valve C12.

The fixed-quantity air tank 3 is filled with air at the atmospheric pressure P2 in a volume V2, and this air instantaneously flows to the side of the sub-tank 2 having a low pressure through 18b, the solenoid valve C12, and the pipe 18a. . As a result, the sub tank 2
Then, the internal pressure of the constant volume air tank becomes P3.

The pressure P1 in the initial state and the pressure P3 in the final state are detected by the pressure sensor 9 and input to a control panel (not shown). Further, the atmospheric pressure P2 is incorporated in the arithmetic expression as a constant. From the above data, the space volume V1 of the sub-tank 2 is obtained using the above-mentioned formula (2) incorporated in a control panel (not shown). Then, by removing V1 from the total volume V3 of the sub tank 2, the liquid amount in the sub tank 2 can be obtained. Furthermore, the bottom area of the sub-tank 2 is a constant, and the liquid amount is divided by the bottom area to obtain a solution of the liquid level. When a series of calculations is completed and the calculation result is larger than the preset lower limit value of the liquid level, the solenoid valve A10, the solenoid valve B1
1, the solenoid valve D13 is opened, the solenoid valve C12 is closed, and the evaporation process is repeated. When the calculation result is smaller than the lower limit value, the solenoid valve E14 is opened to suck the drain (a) of the drain tank 8 into the vacuum chamber 1 and the sub tank 2.

As described above, in the present embodiment, the fixed quantity air tank is provided in addition to the sub tank. However, if the quantity of air introduced into the sub tank when it is separated from the vacuum chamber can be measured, the fixed quantity air tank is provided. Without
The liquid level height can be calculated using the equation (1).

According to the present invention, since the liquid level is measured in the sub-tank provided separately from the low pressure boiling vacuum chamber, the liquid level can be measured with high accuracy without disturbance of the liquid level. Furthermore, since there is no moving part such as a float switch, maintenance is not required, and the measurement accuracy can be maintained for a long period of time.

Although the sub-tank is provided separately from the vacuum chamber in the above embodiment, a partition plate for partitioning the vacuum chamber into two chambers (rooms) and valves above and below the partition plate may be provided. . In this case, a heater is installed in the lower part of the room on one side to heat it so that heat is not transmitted to the other room, and when measuring the liquid level, the valves installed above and below are closed and the other room is closed. It is also possible to open the provided atmosphere supply valve and introduce a predetermined amount of atmosphere for a predetermined time to obtain the liquid surface height by using the above-described equation (1) or equation (2). With this configuration, the sub-tank provided in the previous embodiment is unnecessary, and the device can be downsized.

[0030]

As described above, according to the present invention, (1) the liquid level can be accurately detected by measuring the volume even when the liquid level changes drastically due to the low temperature boiling phenomenon. (2) Since there is no moving part like a float switch, structural reliability is high. (3) The liquid level to be controlled does not need to be replaced with a switch, and can be easily changed only by changing the set value of the arithmetic program of the control panel.

[Brief description of drawings]

FIG. 1 is a flow chart of an embodiment of the present invention and a device configuration diagram.

[Explanation of symbols]

1 ... vacuum chamber 2 ... Sub tank 3 ... Fixed quantity air tank 4 ... condenser 5 ... Cooling fan 6 ... Vacuum pump 7 ... Heater 8 ... Drain tank 9 ... Pressure sensor 10-15 ... Solenoid valve 16-21 ... Piping

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B01D 17/12 B01D 17/12 B C02F 1/40 ZAB C02F 1/40 ZABZ

Claims (2)

[Claims] 1. A tank for storing a drain in which oil and water discharged from a compressed air system are suspended, and a vacuum chamber for evaporating water by utilizing a difference in boiling points of oil and water in a vacuum state. In the oil-water separation device, a sub-tank that maintains the same height as the liquid level of the vacuum chamber is provided, and the communication between the vacuum chamber and the sub-tank is periodically disconnected, and the amount and pressure of air filled in the space inside the sub-tank. An oil / water separator characterized in that the liquid level height is measured from changes. 2. The oil-water separation device according to claim 1, further comprising a fixed-quantity air tank communicating with the sub-tank in order to make the amount of air flowing into the sub-tank constant when measuring the liquid level. Oil and water separation device to be.