JPS6274425A - Gas liquid separation apparatus for water seal type vacuum pump - Google Patents

Abstract

PURPOSE:To enhance the gas-liquid separation efficiency of the emitting stream of a water seal type vacuum pump, by providing gas-liquid separation piping, to which a seal water sump part is provided by partially enlarging the caliber thereof, to this side of the inlet pipe of a cyclone type gas-liquid separation apparatus. CONSTITUTION:A gas-liquid separation piping 15 having a cliber larger than that of emitting piping 4 is provided between a water seal type pump 1 and a gas-liquid separation tank 6. A seal water sump part 19 is provided to the downstream side of the gas-liquid separation piping 15 so as to be suspended from the lower side thereof and the lower part of said water sump part 19 is connected to the gas-liquid separation tank 6. Therefore, the gas-liquid mixture discharged from the pump 1 is lowered in its flow speed because the piping caliber is large at the enlarged part 14 and large water droplets flow in the seal water sump part 9. The gas-liquid mixture containing minute water droplets is raised in its flow speed because the caliber is throttled at the part of gas piping 17 and sent to the cyclone type gas-liquid separation apparatus 6.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to a gas-liquid separation device for a water ring vacuum pump.

[Technical background of the invention and its problems] The problems of conventional gas-liquid separation devices for water-ring type vacuum pumps will be explained by taking vacuum pump equipment for radioactive exhaust gas treatment as an example.

In vacuum pump equipment for radioactive exhaust gas treatment equipment that generally uses a water ring type vacuum pump, when the vacuum pump extracts exhaust gas, water ring type vacuum pumps are used to prevent leakage of the exhaust gas and the incorporation of air, which can reduce pump performance. is adopted.

Therefore, water ring type vacuum pumps are always supplied with seal water.

The exhaust gas discharged from the water ring vacuum pump is mixed with seal water, and the upper part of the discharge piping becomes a mixed air flow containing many water droplets of seal water in the exhaust gas, and the lower part is a two-layer flow with undulating flow of seal water. It has become.

The water seal uses pure water, so in order to reduce the amount used, the water seal is circulated and used continuously. For this reason, a gas-liquid separation tank with gas-liquid separation performance is provided downstream of the water ring vacuum pump.

This gas-liquid separation tank also has the purpose of storing sealed water.

Now, regarding gas-liquid separation in a gas-liquid separation tank, the types of gas-liquid separation are generally a filtration type using a filling such as a wire mesh or a Raschig ring, a collision type, and an expansion type that separates by reducing the flow rate. , a cyclone type that uses centrifugal force, etc. can be considered. Since a sealed structure without flanges is desirable for radioactive exhaust gas treatment equipment, we avoided a filtration type that requires periodic cleaning and instead adopted a cyclone type that is compact and has high separation efficiency.

The problems will be explained below with reference to FIG. 4 and FIG. 5.

The water ring vacuum pump 1 includes an inlet pipe 2 that sucks exhaust gas;
A water nozzle 3 11 into which sealing water is injected is connected to a discharge pipe 4 through which exhaust gas and sealing water are mixed and discharged. The gas-liquid mixed flow of exhaust gas and seal water discharged from the discharge piping 4 passes through a connecting pipe 5 connected to the discharge piping 4 and is transferred to a gas-liquid separation tank 6.
It flows into the interior of the gas-liquid separation tank 6 from an inlet nozzle 7 provided above and in the tangential direction of the gas-liquid separation tank 6 .

Inside the gas-liquid separation tank 6, a sealed water 8 is supplied from a supply water nozzle (not shown) when the water level becomes low by a water level switch (not shown), and is always maintained at a high and low water level so that replenishment is stopped when the water level is high. ing.

The sealed water 8 is forcibly discharged from a sealed water take-out nozzle 9 provided below the gas-liquid separation tank 6 by a circulating pump (not shown), and is cooled by a circulating water cooler (not shown). The cycle of flowing out to water 3 is repeated.

Here, since the inlet nozzle 7 faces in the tangential direction of the gas-liquid separation tank 6, the gas-liquid mixed flow of the exhaust gas and seal water flowing into the gas-liquid separation tank 6 flows in a linear shape along the inner wall of the tank 6. The exhaust gas and sealed water are separated using the common cyclone gas-liquid separation method.

Now, the purpose of the cyclone gas-liquid separation method is to collect the granular condensate that is entrained in the gas and flows, and the centrifugal force of the granular condensate causes it to adhere to the inner wall of the tank 6, forming a continuous liquid film on the wall surface. This system performs gas-liquid separation while supplementing the adhesion of granular condensate and preventing re-scattering.

In the upper part of the pipes such as the connecting pipe 5 and the inlet nozzle 7, a gas-liquid mixed flow is flowing, like the discharge flow of a water ring vacuum pump, with seal water in the form of particles in the exhaust gas flowing. becomes. In addition, in the lower part of the pipe, the seal water, which was discharged at the same time as the exhaust gas and was flowing and turned into relatively large-diameter water droplets, falls and forms a liquid film flow 11 of the seal water. In such a case, if only the mixture 10 is used, gas-liquid separation by the cyclone method can be expected without any problem, but experiments have shown that gas-liquid separation cannot be effectively performed with the gas film flow 11.

When the liquid film flow 11 flows into the gas-liquid separation tank 6, the liquid film flow 11 collides with the wall surface of the gas-liquid separation tank 6, scattering a large amount of water droplets here, and increasing the amount of granular sealed water to be separated. .

Although the nozzle 7 is installed in the tangential direction, the part of the inflowing water that cannot form a spiral liquid film on the inner surface of the tank becomes in a state similar to that of a baffle installed inside the tank 6, so that it is not normal. This causes the swirling flow of gas to be obstructed, making it impossible for the cyclone phenomenon to occur effectively.

The liquid film flow colliding with the wall surface changes its flow direction downward and flows obliquely from above into the water surface of the sealed water 8 stored below the gas-liquid separation tank 6, where it scatters a large amount of water droplets again.

Since the water droplets generated by colliding with the water surface of this sealed water float below the gas-liquid separation tank 6, they cannot be expected to ride on the swirling flow of gas and be separated by centrifugal force.

As described above, the inflow of the liquid film flow 11 into the gas-liquid separation tank 6 not only reduces the gas-liquid separation efficiency due to the cyclone phenomenon of the granular seal water, but also causes a large amount of water droplets to form inside the gas-liquid separation tank 6. This may cause the liquid to be scattered. These unseparated water droplets floating in the gas are sucked into the gas-liquid separation tank 6 through an outlet nozzle 12 extending into the gas-liquid separation tank 6.
This will flow into the downstream piping, and the separation efficiency will be considerably lower than that of the cyclone gas-liquid separation method when only granular condensate flows in.

This causes problems such as condensate accumulation and corrosion in the downstream piping, as well as increased consumption of sealing water using pure water and an increase in the amount of radioactive condensate to be processed.

The liquid film flow 11 collides with the sealed water 8 stored below the gas-liquid separation tank 6, and due to the kinetic energy of the liquid film flow 11, it generates vortices 13 and ripples in the sealed water 8, which causes the water 14 to constantly There is a problem that leads to malfunction of the water level switch that controls the water level to a certain level.

[Object of the Invention] The present invention has been made in order to solve the above-mentioned problems, and provides a gas-liquid separation device for a water-ring vacuum pump that improves the gas-liquid separation efficiency of the discharge flow of the water-ring vacuum pump. The purpose is to

[1lIiii Summary of the Invention] The present invention expands the diameter of the discharge piping of a water envelope type vacuum pump to connect the inlet of the gas-liquid separation piping, and reduces the diameter of the outlet of the gas-liquid separation piping to connect it to the cyclone-type gas-liquid. Connected to the inlet nozzle of the separation tank, a sealed water reservoir is provided on the downstream side of the gas-liquid separation piping, and the lower part of this water-sealed reservoir is connected to the lower part of the gas-liquid separation tank with a water-sealed return pipe. This is a mushroom protection isolation device for water-ring type vacuum pumps. In this device, water droplets fall as the flow rate of the gas-liquid mixed flow of gas seal water discharged from a water ring vacuum pump decreases in the gas-liquid separation piping, sealing most of the seal water that formed the water flow. Collect water in the puddle,
The water is collected through the sealed water return pipe to the sealed water section stored in the gas-liquid separation tank.

This prevents the sealed water that forms this water flow from flowing into the cyclone phenomenon area located at the top of the gas-liquid separation tank.
By allowing normal cyclone gas-liquid separation to occur within the gas-liquid separation tank, the gas-liquid separation efficiency of the discharge flow of the water ring vacuum pump can be improved.

[Embodiments of the Invention] Hereinafter, an embodiment of the gas-liquid separation device for a water-ring type vacuum pump according to the present invention will be described, taking a vacuum pump equipment for a radioactive exhaust gas treatment device as an example, and Figs. 1, 2, and 3. This will be explained with reference to the diagram.

In FIG. 1, the same members as those in FIG. 4 will be described with the same reference numerals.

The gas-liquid separation device for a water-ring type vacuum pump according to the present invention uses a water-ring type vacuum pump 1 and a gas-liquid separation tank 6 as main equipment, similar to the conventional example shown in FIG. This is almost the same as the conventional example. The differences from the conventional example will be explained next.

As shown in FIG. 1, an enlarged part 14 is provided downstream of the discharge pipe 4 to expand the diameter of the discharge pipe 4 downward, and a gas-liquid separation pipe 15 having the same diameter as the enlarged part 14 is provided. Connecting. The diameter D1 of the gas-liquid separation pipe 15 is selected so that the flow velocity of the fluid discharged from the water ring vacuum pump 1 in the gas-liquid separation pipe 15 is 2 m 2 /S or less. In addition, as shown in FIGS. 2 and 3, the pipe 15 became granular as it was entrained in the gas-liquid mixed flow of 1-JI gas and ↑・1 water discharged from the water ring vacuum pump 1. Sealing liquid IlQ flow 11
To speed up the fall of liquid film flow 11 and reduce ripples on the surface of liquid film flow 11 to stabilize the flow. Here, if the flow velocity in the gas-liquid separation pipe 15 exceeds 2111/S, not only does the fall of the granular seal water into the liquid film flow 11 become slower, but also the surface of the liquid film flow 11 slows down. This is undesirable because the ripples become large, water droplets scatter from the tips of the waves, and granular water seals become suspended in the exhaust gas again.

Further, as shown enlarged in FIGS. 2 and 3, a reducing part 16 is provided downstream of the gas-liquid separation pipe 15 to reduce the diameter of the gas-liquid separation pipe 15 by eccentrically increasing the diameter of the gas-liquid separation pipe 15 to the upper side. This reduced portion 16 and a gas pipe 17 having the same diameter are connected. This gas pipe 17 is connected to an inlet nozzle 7 provided tangentially to the gas-liquid separation tank 6 . The diameter D2 of the gas pipe 17 and the inlet nozzle 7 may be determined from the design method of a container intended for general cyclone gas-liquid separation. Similarly, there is no problem with the basic structure of the gas-liquid separation tank 6 that directly affects the gas-liquid separation.

Then, a branch part 18 is provided below from a part of the downstream side of the gas-liquid separation pipe 15, and a water sealing surface part 19 is connected to this branch part 18. As shown in FIGS. 2 and 3, the diameter D3 of the water sealing surface 19 is such that when the liquid film flow 11 flows into the water sealing surface 19, the liquid film flow 11 flows from the entire circumference of the opening. Select a diameter that will meet the conditions. As a guideline, it is determined to be between 0.25 and 1.0 times the diameter D1 of the gas-liquid separation pipe 15, based on the rated flow rate of the water seal. Here, if the diameter D3 of the water seal surface is made extremely small compared to the above guideline, the seal water discharged from the water ring type vacuum pump 1 will be smaller than the water seal that flows into one water seal surface. The number of people in the world will increase relatively.

Therefore, sealing water gradually accumulates in the gas-liquid separation pipe 15, resulting in a narrowing of the exhaust gas flow path. by this,
The flow rate of the exhaust gas becomes faster, which not only causes ripples on the surface of the liquid film flow 11 and scatters water droplets, but also ultimately causes the liquid film flow 11 to flow from the inlet nozzle 7 into the gas-liquid separation tank 6 as in the conventional example. This is an undesirable result. On the other hand, if the diameter D3 of the water sealing surface portion 19 is made larger than the above guideline, the liquid film flow 11 will not flow from the entire circumference of the opening, but will flow only from the upstream side of the gas-liquid separation pipe 15.
In that case, the liquid film flow 11 collides with the wall surface on the opposite side of the opening,
This is undesirable because it generates water droplets and increases the amount of granular water that needs to be separated.

In addition, the length of the gas-liquid separation pipe from the enlarged part 14 to the branch part 18 is approximately 10 times the diameter D1 of the gas-liquid separation pipe, and the drop of the granular seal water into the liquid film flow 11 and the liquid film The ripples on the surface of the flow 11 are sufficiently stabilized. Here, the length β may be set to be 10 times or more than Dl, but this is not preferable because the effect is not improved even though the length is improved and the installation space becomes large.

Furthermore, the lower part of the water seal surface part 19 and the lower part of the gas-liquid separation tank 6 are connected by a water seal return pipe 20. In this case, the opening of the seal water return pipe 20 is always placed below the water level of the seal water 8 stored below the gas-liquid separation tank 6, so that the water inside the gas-liquid separation tank 6 due to the inflow of seal water The structure is designed to prevent water droplets from scattering.

Therefore, the present invention provides (1) a gas-liquid separation pipe 15 having a diameter larger than the diameter of the discharge pipe 4 between the water ring vacuum pump 1 and the gas-liquid separation tank 6; (3) A water seal return pipe 20 is provided below the envelope water reservoir 19 and the gas-liquid separation tank 6. That's true.

Next, the operation of the gas-liquid separator for a water ring vacuum pump will be explained.

The water ring type vacuum pump 1 draws exhaust gas from an inlet pipe 2 and seal water from a water seal nozzle 3 into its interior, and discharges them to a discharge pipe 4 as a gas-liquid mixture. The discharged gas-liquid mixture flows through the gas-liquid separation pipe 15 with its flow rate being lowered because the diameter of the pipe becomes thicker in the enlarged portion 14 . Here, among the sealed water that was entrained in the exhaust gas in the form of small, medium, and large water droplets at the time of discharge from the water envelope vacuum pump 1, relatively medium and
The sealing water, which has become large water droplets, gradually falls below the inner surface of the gas-liquid separation pipe 15 as the flow rate decreases, forming a liquid film flow 11 of the sealing water and flowing below the inner surface. Furthermore, gas-liquid separation piping 1
The ripples on the surface of the liquid film flow 11 caused by falling water droplets etc. are stabilized before reaching the branching part 18 provided below a part of the downstream side of the liquid film flow 11. As described above, in the gas-liquid separation pipe 15, the air-fuel mixture 10 is a gas-liquid mixture of the liquid film flow 11 and the sealing gas, which has become relatively small water droplets and is still flowing along with the exhaust gas. The two-layer flow continues to flow in a stable state.

When the liquid film flow 11 reaches the branch part 18, it flows from the entire circumference of the opening to the water sealing surface part 19, as shown in FIGS.
flows into. At this time, a water belly is formed in the opening by the liquid film flow 11 flowing from the entire circumference. Through this water film,
The liquid film flow 11 does not directly collide with the pipe wall, and the generation of water droplets is prevented.

The membrane flow 11 that has fallen onto the water sealing surface 19, that is, the sealing water, is returned to the lower part of the gas-liquid separation tank 6 through the water seal return pipe 20 that connects the lower part of the water sealing surface 19 and the lower part of the gas-liquid separation tank 6. It flows into the stored sealed water 8 and is collected in the gas-liquid separation tank 6. Here, the seal water flowing in from the water seal return pipe 20 flows below the water surface of the seal water 8 stored below the gas-liquid separation tank 6, so it does not collide with the water surface and scatter water droplets.

The air-fuel mixture 10 flowing through the gas-liquid separation pipe 15 is reduced in diameter by the reducing part 16 installed downstream of the gas-liquid separation pipe, increasing its flow velocity, passing through the gas pipe 17 and the inlet nozzle 7, and separating the gas and liquid. It flows into the tank 6.

The air-fuel mixture 10 that has flowed into the gas-liquid separation tank is separated into gas and liquid using a method that is no different from the general cyclone type gas-liquid separation method, and the sealed water in the form of particles with a particle radius of 5 to 10 μm is captured. collected.

Therefore, in the above embodiment, since the liquid film flow does not directly flow in from the inlet nozzle of the gas-liquid separation tank, it is possible to prevent the scattering of water droplets in the tank and the disturbance of the normal swirling flow of exhaust gas. Increased efficiency. As a result, the problem of drainage accumulation and corrosion in the downstream piping can be reduced, and the amount of sealing water using pure water can be reduced, and the number of radioactive drains to be processed can be reduced. This eliminates the occurrence of sealing errors and rippling of the water stored in the tank caused by the inflow of a liquid film flow into the tank, and it is possible to prevent malfunctions of the water level switch that controls the amount of sealed water.

[Effect of the invention] As described above, the present invention has the following effects.

The gas-liquid separation efficiency of the gas-liquid mixed flow containing many water droplets, which is the discharge flow of a water ring vacuum pump, is improved.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a gas-liquid separation device for a water-ring vacuum pump according to the present invention, and FIG. 2 is a vertical cross-section showing the flow of fluid in the branch part of the gas-liquid separation piping in FIG. 1. Figure 3 is a sectional view taken along the line A-A in Figure 2, Figure 4 is a configuration diagram showing a conventional gas-liquid separation device for a water ring type vacuum pump, and Figure 5 is a sectional view taken along the line A-A in Figure 2.
FIG. 3 is a longitudinal sectional view showing the flow of fluid within the connection between the gas-liquid separation tank and the inlet nozzle shown in the figure. 1... Water ring vacuum pump 2...
・・・・・・・・・Inlet piping 3・・・・・・・・・Water sealing nozzle 4・・・・・・
・・・・・・Discharge piping 5・・・・・・・・・Connecting pipe 6・・・・・・・・・ Gas-liquid separation tank 7・・・
......Inlet nozzle 8...
・Water sealing 9...Envelope ice removal nozzle 10...
......Mixture 11...Liquid film flow 12...Outlet nozzle 13...
...... Vortex 14 ...... Enlarged section 15 ...... Gas-liquid separation piping 16 ...
...... Decreasing part 17 ...... Gas piping 18 ...
......Branch section 19...Water seal measuring section 20...
・・・・・・・・・ Water seal return pipe tube 2 figure 3

Claims (2)

[Claims] (1) A water-seal vacuum pump having an inlet pipe for sucking process gas, a discharge pipe, and a water-sealing nozzle, an enlarged part for expanding the diameter of the discharge pipe downwardly, and a pump connected to the enlarged part. A gas-liquid separation pipe, a reducing part that narrows and reduces the diameter of the gas-liquid separation pipe eccentrically upward, a gas-liquid separation tank connected from this reducing part via a gas pipe, and this gas-liquid separation tank. a seal water take-out nozzle provided below the gas-liquid separation tank; an outlet nozzle provided above the gas-liquid separation tank; a water seal reservoir branched downward from the downstream side of the gas-liquid separation pipe; A gas-liquid separation device for a water-sealed vacuum pump, comprising a water-sealed return pipe that communicates a lower part of the water reservoir with the gas-liquid separation tank. (2) A claim characterized in that the downstream side of the gas pipe is connected to an inlet nozzle provided in a tangential direction of a gas-liquid separation tank, and the outlet nozzle extends into the gas-liquid separation tank. 2. The gas-liquid separation device for a water ring vacuum pump according to item 1.