JPH0524358B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to vacuum pump equipment for radioactive exhaust gas treatment equipment.

[Technical Background of the Invention] Vacuum pump equipment for radioactive exhaust gas treatment equipment that generally uses a water ring vacuum pump is used continuously by circulating sealed water. It is equipped with a circulating water tank with a separation function and a circulating water cooler to suppress the temperature rise of the circulating water. Furthermore, in order to inject seal water into the water ring type vacuum pump, a circulating water pump is often installed and the driving force of this pump is utilized. However, it has become clear that water-ring vacuum pumps can be used by self-circulating water depending on the type of pump, pressure conditions, etc. The present invention improves vacuum pump equipment for radioactive exhaust gas processing equipment, particularly an example in which water is self-circulated using a water ring type vacuum pump.

A conventional example will be explained with reference to FIG. 3, and the technical background of the present invention and its problems will be described.

FIG. 3 is a piping system diagram showing the main parts of the vacuum pump equipment for the radioactive exhaust gas treatment equipment. The exhaust gas is sufficiently reduced in radioactivity by equipment on the upstream side of the vacuum pump equipment (not shown), passes through the inlet piping 1 of the vacuum pump equipment, and is sucked into the water ring type vacuum pump 2. The water ring type vacuum pump 2 receives circulating water as a seal from a water seal nozzle 3 while pushing the exhaust gas together with the water seal into a discharge pipe 4 and sends it into a circulating water tank 6 from a circulating water tank inlet nozzle 5. The circulating water tank 6 separates the inflowing exhaust gas and sealed water, and the sealed water is stored at the bottom with a certain capacity secured, and the exhaust gas is discharged from the circulating water tank outlet nozzle 7 provided above the tank 6. It will be sent to an exhaust tower (not shown) through the pipe 12 and released into the atmosphere. A portion of the exhaust gas from the circulating water tank outlet nozzle 7 is returned to the inlet pipe 1 by an exhaust gas recirculation line 8, and the flow rate of this exhaust gas is regulated by a flow rate control valve 13. In other words, the vacuum pump equipment is located at the most downstream part of the radioactive exhaust gas treatment equipment and has the function of keeping the entire equipment at negative pressure while flowing the exhaust gas. When the water level in the circulating water tank 6 is lowered by a water level switch (not shown), water is supplied by the supply water nozzle 9 until the water level reaches a high level, and the system is always operated at a water level between low and high. The sealed water taken out from below the circulating water tank 6 is discharged from the outflow pipe 14.
By the driving force of the circulating water pump 10, the circulating water passes through the circulating water cooler 11 and then through the communication pipe 15, and is injected into the water seal vacuum pump 2 from the water seal nozzle 3.

Now, regarding the steam/water separation in the circulating water tank 6, the types of steam/water separation are generally a filtration type using a filling such as a wire mesh or a Raschig ring, a collision type, an expansion type that separates by reducing the flow velocity, A cyclone type that uses centrifugal force can be considered. For radioactive exhaust gas treatment equipment, it is desirable to have a sealed structure that does not include flanges, so avoid using a filtration type that requires regular cleaning, and instead use a cyclone type that is small and has high separation efficiency.
It is used in

[Problems with the Background Art] In FIG. 3, the mixture of sealed water and exhaust gas flowing from the circulating water tank inlet nozzle 5 in the tangential direction to the body of the circulating water tank 6 comes into contact with the body and collides with the body. In addition to providing the same effect as the above, the fluid flows downward while being rotated, the water is attached to the inner wall by centrifugal force and separated, and the exhaust gas is released from the center to the upper outlet nozzle 7. Therefore, in the design of the equipment, the height dimension a to obtain a swirling flow, and the dimension b to prevent water droplets from entering the upward flow in the center, are preferably about 2 to 3 times the diameter of the inlet nozzle 5. Efficiency decreases with decrease. Therefore, the height a+b between the inlet nozzle 5 of the circulating water tank 6 and the control liquid level is inevitably restricted to a certain level or more.

By the way, as for the vacuum pump equipment, if possible under the pressure conditions, the sealed water is circulated by self-circulation, that is, by the pressure difference between the discharge pressure of the water ring type vacuum pump and the three parts of the water sealing nozzle, rather than being driven by the circulating water pump 10. The system configuration will be simpler and cheaper if configured in this way. In particular, when dynamic equipment such as radioactive exhaust gas treatment equipment is duplicated or has various control interlocks in anticipation of failure, annual periodic inspections of the installation space, electrical instrumentation, and radioactivity control areas are required. There is a big difference in terms of reliability and cost. Therefore, a self-circulation type vacuum pump equipment is desired.

However, as mentioned above, the required dimension a+b between the inlet nozzle 5 of the circulating water tank 6 and the control liquid level is
However, due to the arrangement, a water head difference c between the water seal vacuum pump 2 and the control liquid level is created, resulting in a reverse pressure when sending seal water, making it difficult to realize the above request. Furthermore, it is not possible to achieve the necessary condition of filling the main shaft level of the water ring pump with water, especially at startup.

It is also possible to raise the position of the circulating water tank 6 so that the water level on the circulating water tank 6 side is higher than the main shaft level of the vacuum pump 2, but in this case, in order to guide the discharge pipe 4 to the circulating water tank inlet nozzle 5, It is necessary to start up with gas piping, and with this piping structure, seal water accumulates in the discharge piping 4 when the vacuum pump 2 is stopped, and when the vacuum pump 2 is restarted, a gas-liquid mixture is not formed and only water is circulated. There is a problem that it is supplied to the tank and obstructs the function of the cyclone. On the other hand, if priority is given to the startup conditions, problems will arise in the design of the circulating water tank, such as air-water separation efficiency, maintenance, and dimensions of the circulating water tank. For example, lowering the steam/water separation efficiency increases the amount of water that scatters to the outlet piping 12, causing problems such as condensate accumulation and corrosion in the piping, and also increases the consumption of circulating water using pure water.

[Purpose of the Invention] The present invention has been made to solve the above-mentioned problems, and it allows self-circulation of the water sealed in a water ring type vacuum pump, and at the same time has high steam/water separation efficiency, and also solves problems in terms of equipment maintainability. It is an object of the present invention to provide a highly reliable vacuum pump equipment for a radioactive exhaust gas treatment device that does not cause spots.

[Structure of the Invention] The present invention provides a water-seal vacuum pump having an inlet pipe for sucking in radioactive exhaust gas, a discharge pipe, and a water-sealing nozzle, a vertically branched branch part to which the discharge pipe is connected, and this branch part. A circulating water tank connected from above via a gas pipe, a supply water nozzle and an outflow pipe connected below the circulating water tank, and a circulating water cooler connected to the downstream side of the outflow pipe. A communication pipe connecting the downstream side of the circulating water cooler and the water sealing nozzle, a prebalance pipe interposed and communicated between the lower side of the branch part and the outflow pipe, and the circulating water tank an outlet nozzle provided above, and a water level switch that controls the water level in the circulating water tank to be between the main shaft level of the water ring vacuum pump and the discharge piping level of the water ring vacuum pump. This is vacuum pump equipment for a radioactive exhaust gas treatment device, which is characterized by the following:

[Embodiment of the Invention] An embodiment of the vacuum pump equipment according to the present invention will be described below with reference to FIGS. 1 and 2. In FIG. 1, the same members as those in FIG. 3 will be described with the same reference numerals.

The vacuum pump equipment according to the present invention mainly includes a water ring vacuum pump 2, a circulating water tank 6, and a circulating water cooler 11, as in the example shown in FIG. As shown in the figure, a branch part 16 is provided in the discharge pipe 4, and a gas pipe 17 and a prebalance pipe 1 are connected to this branch part 16.
It consists of 8 connected. In Figure 1,
An inlet pipe 1, a water seal nozzle 3, and a discharge pipe 4 are connected to the water ring type vacuum pump 2, and on the downstream side of the discharge pipe 4, a branch part 16 is connected to the gas pipe 17 and the prebalance pipe 18. is provided. A gas pipe 17 formed by bending upward from the branch portion 16 is connected to a circulating water tank 6 via an inlet nozzle 5. An outlet nozzle 7 is connected to the circulating water tank 6, and an outlet pipe 12 is connected downstream of the outlet nozzle 7.

Further, the outlet pipe 12 and the inlet pipe 1 are connected by an exhaust gas recirculation pipe 8 including a flow rate control valve 13. On the other hand, the water sealing piping includes an outflow piping 14 that is taken out from below the circulating water tank 6 and reaches the circulating water cooler 11, and an outflow piping 14 that is joined to this piping 14 and is branched from the discharge piping 4. It consists of a prebalance pipe 13 disposed downward from a branching part 16 from the circulating water cooler 11 and a communication pipe 15 leading from the circulating water cooler 11 to the water sealing nozzle 3 of the water ring vacuum pump 2. A water level switch (not shown) is attached to the circulating water tank 6 and adjusts the water level to high and low set levels during operation. The air/water separation section and water level control of the circulating water tank have almost the same configuration as the conventional example.

That is, when the water level in the circulating water tank 6 falls to the water level low level set near the main shaft level, the water level switch is activated and water is supplied from the supply water nozzle 9 to the inner lower part of the discharge pipe 4 which is higher than the water level low level. When the water level reaches the set level, the water level switch is activated again and the water supply is stopped.

FIGS. 2a, 2b, and 2c are specifically enlarged sectional views of examples of pipe joints 16a, 16b, and 16c used in the branch portion 16 branching from the discharge pipe 4 in the embodiment of the present invention. Figure 2a shows a combination of a tee 19 and a reducer 20, Figure 2b shows a combination of a different-diameter tee 21 and reducers 22, 23, and Figure 2c shows a combination of a different-diameter tee 21, a reducer 22, 23, a cap 24, and a half coupling 25. The outer half of the elbow is attached as a collision plate 26 inside a tee 21 of different diameter. The pipe joints 16a, 16b, and 16c used in this branch part 16 are used to take out part of the liquid flowing below the inner surface of the discharge pipe 1 and forming large droplets, and the water is removed in the order of c, b, and a. Easy to separate. These joints a, b, and c can have deformable structures depending on flow conditions and the like.

Next, the operation of the vacuum pump equipment described above will be explained.

Exhaust gas from the radioactive exhaust gas treatment device is extracted from an inlet pipe 1 to a water ring vacuum pump 2, and the exhaust gas can be made to flow while maintaining the entire device at a negative pressure.
The water ring type vacuum pump 2 draws exhaust gas from the inlet pipe 1 and seal water from the water seal nozzle 3 into the interior thereof, and discharges them to the discharge pipe 4 as a gas-liquid mixture. At this time, the water seal acts as a seal and removes frictional heat. In the discharge piping 4, the gas-liquid mixture is separated downward at the branching part 16 from the part of the water that flows as a liquid film on the inner surface of the piping and flows into the pre-balance pipe 18, reducing the liquid ratio of the mixture and transferring it to the circulating water tank. It reaches the inlet nozzle 5. In the circulating water tank 6, the exhaust gas is efficiently separated and removed from sealed water by a steam/water separation mechanism designed with reasonable dimensions between the circulating water tank inlet nozzle 5 and the control water level, and is then discharged from the circulating water tank outlet nozzle 7. Outlet piping 12
It is sent to an exhaust tower (not shown) through the air. In addition, a part of the exhaust gas is returned to the inlet pipe 1 side by the exhaust gas recirculation pipe 8 including the flow rate control valve 14, thereby controlling the pressure and flow rate within the radioactive exhaust gas processing apparatus.

The sealed water accumulated in the circulating water tank 6 and the sealed water supplied from above to the prebalance pipe 18 are cooled by the circulating water cooler 11 and then supplied from the sealed water nozzle 3 to the water ring type vacuum pump 2. This cycle continues.

Note that the water level in the prebalance pipe 18 differs from the water level in the circulating water tank 6 by the flow pressure loss, but since it is connected at the bottom, it is operated in a balanced manner with an almost constant and slight difference. . In this embodiment, the difference in the amount of water supplied from above to the front balance pipe 18 and the circulating water tank 6 is automatically adjusted by the amount of water flowing to the circulating water cooler 11 in response to the head and flow pressure loss. receive.

However, in the above embodiment, even when the vacuum pump equipment is stopped, the control water level is almost at the main shaft level of the water ring vacuum pump, and the water seal is submerging the water ring vacuum pump, so there is no need to perform any preliminary water injection work. It can be started without any problem.

Furthermore, compared to the case where water is sealed and circulated using two units, a water ring type vacuum pump and a circulating water pump, an operating condition with less noise and vibration can be obtained.

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

Eliminates the need for circulating water pumps that complicate the control system.
Reliability is improved, operation is easy to understand, and maintenance and inspection are easy.

In addition, we have installed a branch section in the discharge pipe that branches vertically, and a balance pipe between the lower side of the branch section and the outflow pipe of the circulating water tank, so that water that flows as a liquid film on the inner surface of the pipe can be prevented. It flows into the balance tube to reduce the liquid ratio of the gas-liquid mixture. If another gas-liquid separation device such as a cyclone is attached to the circulating water tank, the load can be reduced.

Therefore, the circulating water tank can be made smaller and the installation space can be reduced, which is also economical.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the vacuum pump equipment for radioactive exhaust gas treatment equipment according to the present invention, and FIG. 2 is a vertical cross-sectional view showing an enlarged view of a piping joint used in a branch part of the discharge piping in FIG. 1. The top view and FIG. 3 are configuration diagrams showing conventional vacuum pump equipment. 1...Inlet piping, 2...Water ring vacuum pump, 3
... Water sealing nozzle, 4 ... Discharge piping, 5 ... Inlet nozzle, 6 ... Circulating water tank, 7 ... Outlet nozzle,
8... Exhaust gas recirculation piping, 9... Supply water nozzle,
10... Circulating water pump, 11... Circulating water cooler,
12... Outlet piping, 14... Outflow piping, 15...
Communication piping, 16...branch section, 16a, 16b, 1
6c...Piping joint, 17...Gas piping, 18...
Front balance tube.

Claims (1)

[Claims] 1. A water ring vacuum pump having an inlet pipe for sucking in radioactive exhaust gas, a discharge pipe, and a water seal nozzle;
A vertically branching branch connected to the discharge pipe, a circulating water tank connected from above the branch via a gas pipe, and a supply water nozzle connected below the circulating water tank. and an outflow pipe, a circulating water cooler connected to the downstream side of the outflow pipe, a communication pipe connecting the downstream side of the circulating water cooler and the water sealing nozzle, and a lower side of the branch part and the outflow pipe. and an outlet nozzle provided above the circulating water tank, and the water level in the circulating water tank is adjusted to the main shaft level of the water ring vacuum pump and the water ring type vacuum pump. Vacuum pump equipment for radioactive exhaust gas processing equipment, characterized in that it is equipped with a water level switch that controls the water level to be between the discharge piping level of a sealed vacuum pump.