JPS5854843B2 - Device that automatically separates oil from high-temperature oily water - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for automatically separating oil from high-temperature oily water.

For example, after the steam generated in a boiler has been used for heating and other purposes, the condensate condensed is stored in a condensate tank and used again as boiler water.

Of course, the amount lost will be replenished with newly produced pure or soft water.

When steam is used to heat an oil tank or the like, oil may leak into the heating pipes, causing oil to mix into the condensate and return to the condensate tank as oily water.

Needless to say, this oil must be removed in order to recycle the condensate to the boiler.

When oily water is placed in a condensate tank, it separates into two layers: oil and water, so once a certain amount of oil has accumulated, the surface layer can be skimmed, or a part of the surface layer can be constantly blown to separate and collect the oil in the blown water. Conventionally, methods of detecting oil content have been taken.

In the former case, it is not possible to immediately know when oil contamination begins and take necessary measures, so oil continues to leak until regular checks are made.

In addition, although the latter has good response, there is a waste of constant blowout because it separates and detects oil that may be mixed in at any time, and an increase in the amount of pure water or soft water to be replenished is unavoidable.

The object of the present invention is to solve this problem and provide a device that promptly responds and automatically separates condensate when oil is mixed in, thereby reducing the loss of condensate during oil separation and detection. It is about providing what is almost lost.

The device of the present invention creates low-temperature water by cooling a portion of high-temperature oily water introduced into a condensate tank, and uses the difference in specific gravity between the high-temperature water and the high-temperature water to skim the surface layer of high-temperature condensate. In addition to obtaining the necessary head height,
This is based on a principle first conceived by the present inventor, in which the low-temperature, high-density water layer from which the oil is separated is returned to the tank by its own weight without requiring any energy.

The apparatus for automatically separating oil in high-temperature oily water according to the present invention will be explained below with reference to the drawings. As shown in Figure 1, this apparatus can separate high-temperature oily water such as condensate. A tank 1 to be introduced, a cooling pipe 2 installed in parallel to it, a lower communication pipe 31 connecting 7 parts of the tank and the lower part of the cooling pipe, and an upper communication pipe 32 connecting the upper part of the tank and the upper part of the cooling pipe. consists essentially of

The cooling pipe has a height equal to or higher than the full water level of the tank.

It is desirable to provide a valve (not shown) in the lower communication pipe in preparation for when the system is stopped.

Skimming of the oil layer is performed in the upper communication pipe.

Although the upper communication pipe itself can be used as the skimming means, it is recommended to use the skimming means 33 made of slits or wear.

The shape may be arbitrary, such as a rectangular shape as shown in FIG. 2A, a lattice shape as shown in FIG. 2B, or a half-moon shape as shown in FIG.

Further, the lower edge of the opening does not necessarily have to be linear on the same horizontal line, but may be a groove shape as shown in the figure or an arc shape as shown in E.

This skimming means may be located anywhere on the tank side, in the cooling control, or in the upper communication pipe (in the figure, it is located approximately in the center of the communication pipe).

) In any case, if a specific skimming means is used, its lower edge will form the "lower edge of the opening" of the upper communicating pipe.

In short, the lower edge of the opening here refers to the highest part of the upper communication pipe that must be crossed when the oil-containing liquid moves from the tank to the cooling pipe.

It goes without saying that the upper communication pipe may be inclined or curved.

The cooling v2 is provided with an oil discharge pipe 4.

The mounting position is at the upper part of the cooling pipe, and the lower edge of the opening is lower than the lower edge of the opening of the upper communication pipe, but is set higher than the height determined by the formula described later.

The opening of the oil discharge pipe 4 may be tubular or may have a shape similar to that used for the above-mentioned skimming means.

A water-blocking layer 11 is provided inside the tank 1 to separate the contents.

The height of its upper edge is substantially equal to the height of the lower edge of the opening of the upper communication pipe.

This "substantially equal height" will be explained later.

The lower part of the water-blocking layer 11 forms a continuous wall surface up to the bottom of the tank.

Of course, the joints between the inner wall and bottom of the tank and the waterproof layer are sealed by welding or the like.

Inside the tank 1, an oil shielding weir 12 is further provided on the side closer to the upper communication pipe than the water shielding layer.

The upper edge is set at a position higher than the full liquid level defined by the impermeable layer, and more specifically, the height is set to such a level that the undulating liquid level and splashes caused by the inflow of condensate do not exceed the oil impermeable weir.

The lower edge is located at a sufficiently deep position so that it is below the full liquid level and below the F limit of the interface between the oil-water mixed phase and the aqueous phase that is generated in the tank when oily condensate is introduced.

However, the space between the oil barrier weir and the bottom of the tank must be open so that the condensate separated from the oil can move to the side where the water barrier layer is located.

The inlet pipe 14 for the high temperature oily condensate is provided on the side of the tank wall closer to the upper communication pipe 32 than the oil shield weir 12.

Its height is determined in relation to the height of the lower edge of the oil barrier weir 12, that is, to prevent oily water from directly moving toward the barrier layer.

Normally, it is sufficient to install it near the full liquid level. An outlet pipe 15 for condensate from which oil has been separated is provided at a link portion on the opposite side of the upper communication pipe 32 with respect to the water-blocking layer 11.

The oil-water separation function of the apparatus of the present invention having the above-mentioned configuration will now be explained with reference to FIG.

First, when high temperature condensate enters the tank from the inlet pipe 14, it also flows into the cooling pipe 2 through the lower communication pipe 31.

Since the cooling tube is much smaller than the tank body and has a larger specific surface area relative to its capacity, the condensate in the cooling tube will have a lower temperature and therefore a higher specific gravity than that in the tank.

Now, the average specific gravity of the high temperature condensate in the tank is ρ.
The average specific gravity of the low-temperature condensate in the t1 cooling pipe is ρW
If the height from the upper edge of the opening of the lower communicating pipe to the upper edge of the water-blocking layer is ht, then the height of the liquid level in the cooling pipe when there is no oil layer is also hwl from the upper edge of the lower communicating pipe.
is expressed by the following formula [1].

In order to prevent water from overflowing from the oil discharge pipe 4 when there is no oil and only a water layer, the height hc of the lower edge of the discharge pipe opening (also from the upper edge of the lower communication pipe opening) must be set according to the above formula. must be larger than hw' defined by .

In this way, the installation position of the oil discharge pipe is determined.

Now, if oil is mixed into the condensate and enters the tank as a mixed phase of oil and water, the oil and water will first separate in the tank separated by the oil barrier layer 12 (on the left in the figure), and the oil will float to the surface layer. , the water layer passes through the bottom of the oil barrier layer and reaches the water barrier layer 1.
1 overflows and accumulates on the opposite side (on the right side in the figure).

Since this is an oil-free condensate, it is taken out through the outlet pipe 15 and used again.

The oil floating on the surface layer of the condensate on the inlet side of the oil barrier layer is skimmed together with a portion of the water layer by the skimming means 33, and flows into the cooling pipe 21 through the upper communication pipe 32.

As mentioned above, the water layer within the cooling tube is cooled over its entire height and has a high specific gravity.

The oil layer gathers on the surface layer of the cooling pipe, which has a significantly smaller diameter than the tank, increases in thickness, and reaches a steady state under the condition f.

However, hw2 is the height of the water surface inside the cooling pipe when there is an oil layer (this is also from the upper edge of the opening of the communication pipe), ho is the thickness of the oil layer, and ρ0 is the specific gravity of the oil layer. .

hc, ρt, and ρW are as described above.

If the oil content increases beyond this steady state, it will overflow from the cooling pipe through the oil discharge pipe.

If an oil storage tank 5 is prepared at the end of the oil discharge pipe and a float switch 51 is installed there, oil leakage can be quickly detected.

Even if oil gets mixed into the condensate, the float switch will not operate until the amount of oil at the top of the cooling pipe and bottom of the oil storage tank accumulates, so there will be a slight time lag between when oil starts getting mixed in and when it is detected. It turns out.

However, this can be minimized by designing the dead space to be as small as possible or by filling it with an appropriate amount of oil in advance.

On the other hand, the water that has flowed into the cooling pipe 2 beyond the steady state is cooled and has a specific gravity of 100%, so it naturally circulates to the lower part of the tank 1 via the f-toll communication pipe 31.

As will be readily understood, the opening of the lower communicating pipe may be in the tank wall, and since the water entering from it no longer contains oil, it is possible to extend the pipe close to the water barrier layer. Good too.

Considering the height of the upper edge of the impermeable layer, first of all, if it is at exactly the same height as the lower edge of the opening of the upper communication pipe, then as new condensate flows in, the impermeable layer and the upper An overflow of condensate surface occurs from both pipes.

The flow rate ratio is roughly proportional to the width of the two (ignoring the difference in specific gravity and viscosity between pure water and the oil-water mixed phase, and the influence of the shape of the skimming means).

Now, the upper communication pipe is 1/100th that of the water-blocking layer.
If so, the amount of liquid passing through the former can be considered to be 1/100 of the amount of liquid exceeding the latter (outflow condensate amount - inflow condensate amount).

If there is no new inflow of condensate, the overflow from the above-mentioned upper communication pipe and impermeable layer will stop.

The height of the water-blocking layer 12 is the height ht of the lower edge of the upper communication pipe opening.
If the height is slightly higher (on the order of a few millimeters), even when there is no new inflow of condensate, the flow of liquid overflowing through the upper communication pipe will still be cooled by the cooling pipe, as understood from the above. , will continue as long as it lasts.

(Of course, if there is no inflow of new condensate, there will be no new oil mixed in, so there is no point in making it higher.

) Conversely, even if the height of the upper edge of the water-blocking layer 11 is slightly lower than the height ht of the lower edge of the upper communication pipe opening, a large amount of condensate flows into the tank and overflows beyond the water-blocking layer. Since the liquid level rises, the liquid level in the oil barrier layer also rises, and the surface layer flows into the cooling pipe through the upper communication pipe.

If waves occur on the liquid surface, this will be promoted.

In this way, the height of the water-blocking layer can have a certain width around the height ht of the lower edge of the opening of the upper communication pipe.

The above-mentioned "substantially equal height" includes all such cases, and when there is an inflow of condensate,
It means the height at which the liquid at the tank surface can flow into the cooling pipe through the upper communication pipe and maintain the necessary liquid level for automatic skimming as intended by the present invention.

If new condensate is constantly flowing into the tank, the temperature inside the tank is normally maintained at a temperature of 80 to 90'C.

On the other hand, in the cooling pipe, the amount of liquid flowing through the upper communication pipe is reduced to one-hundredth, for example, as described above.

Since the ratio of surface area to volume is significantly different between a tank and a cooling pipe, even if the cooling pipe is made of bare tubes, it is easy to cool the bottom of the cooling pipe to 40 to 50°C by being cooled by the outside air. .

That is, the average temperature of the condensate in the cooling pipe is 60
~70℃, and between it and the condensate in the tank,
An average difference of 20'C or more can be produced.

If the surface area of a single bare cooling tube is insufficient, it may be configured as a finned tube or divided into a plurality of bare tubes.

Furthermore, when the present invention is carried out under conditions where the outside air temperature is extremely high, the cooling tube may have a double-tube structure in which an outer tube is provided, and cooling may be performed by water cooling.

These are all embodiments of the present invention.

In addition, various embodiments of the device of the present invention are possible. For example, as shown in FIG.
1 and the cooling pipe 2 may be constructed integrally.

It is clear from the principle of the present invention described above that the opening of the lower communication pipe should be understood as the place where the condensate cooled in the cooling pipe to a low temperature flows back into the tank and comes into contact with the high temperature condensate. .

Above, the device for automatically separating oil in high-temperature oily water according to the present invention has been explained using steam condensate generated by a boiler as a target, but steam condensate is the most typical example. It should be understood that the apparatus of the present invention can essentially treat oily water at high temperatures even if it has other origins.

Design example (1) If the average liquid surface temperature of the cooling pipe when no oil is present is 80°C inside the tank and 60°C inside the cooling pipe, then ρt
=0.972, ρw=0.983If the height ht of the lower edge of the upper communication pipe opening is selected to be 500CrrL, then according to the above formula,
The height of the water surface inside the cooling pipe is 494.4Cn'L, which is 5
．． A head difference of 6cIfL is generated.

In order to prevent the water in the cooling pipe from flowing to the oil discharge pipe, the height hc of the lower edge of the opening must be 494.4CrfL or more.

(2) When an oil layer is formed at the top of the cooling pipe and oil begins to be discharged, assume that the height hc of the lower edge of the opening of the oil discharge pipe is selected to be 496 crfL based on the above results.

Assuming that the specific gravity of the oil is 0.9 and the temperature conditions are the same as above, the above equation yields hw2-477cIrL hO-19crfL.

That is, only oil flows out into the oil discharge pipe with an oil layer having a thickness of 19 cIfL formed at the upper part of the cooling pipe.

At this time, the head difference hd between the lower edge of the skimming means and the liquid level in the cooling tube is 4CrfL.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing the configuration of an example of the apparatus of the present invention, and FIGS. 2A, B, C, D, and E are views showing various aspects of the oil layer skimming means. FIG. 3 is a diagram for explaining the operation of the apparatus of the present invention. FIG. 4 is a sectional view similar to FIG. 1 showing another example of the device of the present invention. 1...Tank, 11...Waterproof layer, 12
... Oil shielding base, 14 ... Inlet pipe, 15.
...Exit pipe, 2...Cooling pipe, 31...
... F capital communication pipe, 32 ... Upper communication pipe, 4.
...Oil discharge pipe, 5...Oil storage tank.

Claims (1)

[Claims] 1. A tank 1 that introduces high-temperature oily water, a cooling pipe 2 installed in parallel to the tank, a lower communication pipe 31 connecting the lower part of the tank and the lower part of the cooling pipe, and the upper part of the tank. The cooling pipe is comprised of an upper communication pipe 32 that connects the upper part of the cooling pipe, and the cooling pipe is provided with an oil discharge pipe 4 having an opening lower edge at a position lower than the lower edge of the opening of the upper communication pipe, and the tank 1 has an oil discharge pipe 4 in which the above-mentioned communication pipe is connected. a water-blocking layer 11 having an upper edge at a height substantially equal to the lower edge of the opening of the pipe and a continuous wall surface to the bottom of the tank;
and has an upper edge located at a side closer to the upper communication pipe than the impermeable layer and higher than the full liquid level defined by the impermeable layer,
It also has a lower edge at a position lower than the full liquid level, and is provided with an oil shielding weir 12 that is open between the lower edge and the bottom of the tank, and a side of the tank wall closer to the upper communication pipe than the oil shielding weir. It has an inlet pipe 14 for hot oily water that opens at the bottom of the tank, and an outlet pipe 15 that opens at the bottom of the tank on the opposite side of the upper communication pipe with respect to the impermeable layer. It is characterized by being installed so that the height hc from the edge to the lower edge of the opening of the oil discharge pipe in the cooling pipe is smaller than the height hw' of the water surface in the cooling pipe when there is no oil layer, which is shown by the following formula. A device that automatically separates oil from high-temperature oily water. In the above formula, ht: 1' Height from the upper edge of the partial communication pipe opening to the upper edge of the impermeable layer ρt: Average specific gravity of high-temperature oily water in the tank ρw: Average specific gravity of low-temperature oily water in the cooling pipe 2. The device according to claim 1, wherein an oil collection tank 5 is provided at the end of the oil discharge pipe 4, and a float switch 51 is installed in the oil collection tank. 3. The device according to claim 1 or 2, wherein the cooling pipe is a bare pipe or a finned pipe, and the high temperature oily water is cooled by air cooling. 4. The device according to claim 1 or 2, wherein the cooling pipe is a double pipe, and the high temperature oily water is cooled by water cooling.