JPH02138595A - U-shaped pipe structure - Google Patents

Abstract

PURPOSE:To improve the workability of a filter unit by disposing a flow resisting body consisting of an orifice in and around the lower end of a U-shaped pipe exhausting drain water. CONSTITUTION:A U-shaped pipe 1 connected to a filter unit proceasing mists and dusts in a processing chamber for exhausting drain water which contains a liquid is divided into two parts with a flange part on its one end. A flow resisting body 2 having an orifice structure 3 in its inside is disposed between the halved U-shaped pipes and fixed to the flange part of the U-shaped pipe 1. Consequently, the dimension of the U-shaped pipe used to exhaust drain water can be reduced by half, and the workability of the filter unit to which the U-shaped pipe can be significantly improved.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a U-shaped pipe structure for treating drain water such as a filter for removing mistakes, and in particular, the liquid level of seal water is The present invention relates to a U-shaped tube structure that is suitable for suppressing vibration, ensuring the required length of the U-shaped tube, and the stability of the seal water surface when measuring the seal water level.

[Conventional technology] A conventional example will be explained using FIG.

The vertical length of the U-shaped tube 1 connected to the filter unit 7 that processes mist and dust in the processing chamber 6 is sealed by the water surface vibration of the seal water inside the U-shaped tube that occurs when the fan 8 is started or stopped. It is necessary to ensure a sufficient length so that the water 5 is not discharged from the filter unit 7 or the drain pipe line 9 all at once and the seal water 5 is not lost from the U-shaped pipe 1.

The conventional method for setting the required length of a U-shaped tube in the upward and downward directions is shown below.

When the fan 8 is started, the pressure inside the filter units 1 to 7 is x
In the case of a negative pressure of mm A g, the water surface of the U seal water on the filter unit 7 side will overshoot the equilibrium water level x/2 at this time by x/2 from the water surface at the time of stop in two directions in the figure, and reach the maximum rises to.

As shown in Fig. 3, the water level of the seal water on the side toward the filter unit 1 is centered on the water level 10, which is x/2 higher than the water level of the seal water when stopped, on the drain pipe line side. The water level of the seal water is x/2 lower than the water level 11
It vibrates around. Due to this vibration, the rainwater level drop of the seal water increases to a maximum of 2x.

Therefore, the upper and lower dimensions of the U-shaped tube must be at least 2x. If this cannot be ensured, all of the seal water 5 flows into the filter unit 7 when the fan 8 is started, overflowing into the filter unit 7, and causing water damage to the dust filter 12 installed downstream of the mist removal filter 4.

4 and 5 are diagrams for explaining the workability of the U-shaped pipe 1. FIG.

Since the J-shaped tube is installed at the bottom of the filter unit 7, when installing the filter unit 7 on the floor 13 of the lowest floor, the filter unit must be installed at least the required length (2x) of the 11-shaped tube in the upward and downward directions. It was necessary to lift it up using the support stand 14 or the like.

The required length of this U-shaped tube in the upper and lower directions is approximately 400 mm, assuming that the cut-off lift of the fan 8 is 200 to 1000 mm A g.
~2000 nm is required. If the cut-off lift of the fan is 1100 OnniA, it is necessary to lift the filter unit 7 by 2000 m using the support stand 14 or the like, but the filter unit 7 may collide with the ceiling 15 and cannot be lifted. In this case, it was necessary to take measures such as installing the filter unit 7 on the rooftop 16 or on an upper floor.

FIG. 6 is a diagram illustrating a conventional problem when checking the level of seal water in a U-shaped pipe. Theoretically, the seal water surface vibration shown in FIG. 3 can be repeated for an infinite time if there is no flow resistance between the seal water and the U-shaped tube. In reality, there is some flow resistance, so it gradually dampens, but it takes U
It takes about 10 minutes, depending on the dimensions of the tube and the degree of negative pressure generated in the filter unit when the fan is started, and it is impossible to confirm that seal water is properly secured immediately after the fan is started. there were.

[Problem to be solved by the invention]

In the above conventional technology, the seal water 5 in the U-shaped pipe vibrates greatly when the fan 8 is started, and the difference between the seal water level in the U-shaped pipe and the required head (equilibrium head It was necessary to take the length in the upward and downward directions twice (2x) the equilibrium head. As a result, when arranging the filter unit 7, it is necessary to take measures to raise the filter unit 7 higher than necessary on the support stand 14, etc., and to reduce the installation room of the filter unit.
Measures such as changing to the roof 16 or upper floors were required, which caused a big problem in construction.

The purpose of the present invention is to reduce the required length of the U-shaped tube in the upward and downward directions by reducing the required length of the U-shaped tube in the upward and downward directions to about the minimum required equilibrium head (x), and to reduce the required length of the U-shaped tube in the upward and downward directions. Units l-7
The aim is to improve the workability of.

(Means for solving the problem) The above object is achieved by installing a flow resistor 2 in a conventional U-shaped tube 1 at or near the lower end of the U-shaped tube, as shown in FIG. Ru.

[Effect]

Since the installed flow resistor 2 provides a damping action to the vibration of the U-seal water when the seal water vibration phenomenon in the 0-shaped pipe occurs, overshoot of the U-seal water can be suppressed as much as possible.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a side view showing an embodiment of the present invention, in which a U-shaped tube 1 containing a liquid is divided into two parts each having a flange at one end. A flow resistor 2 having an orifice structure 3 inside is installed between the two divided U-shaped tubes, and
It is fixed to the flange portion of the tube 1 with bolts.

Figure 7 is a model for analyzing the vibration of liquid inside the U-shaped tube 1, where the length of the liquid column is Q, the diameter of the tube is d, the friction loss coefficient inside the tube is λ, and the local loss coefficient is ξ and 1 gravitational acceleration as g, three cases in which the ratio of the cross-sectional area Ax of the pipe to the area Az of the hole in the orifice 3 are different are analyzed. However, the specifications of the model to be analyzed shall be the values listed in the table.

The initial conditions are that the same pressure is applied from both ends of the U-shaped tube 1 and the water levels are balanced, but at time 1 = 0, the pressure P = 500 [ma + Agl is applied from one side of the U-shaped tube, and then We will analyze the vibration of the liquid level.

Assuming that the water level from the center of vibration is variable 2, the equation of motion in U-shaped tube 1 is: The approximate solution to the above equation is as follows.

Z= acos (ωOt,) a = 1+□ε0ωoaot 3 π However, aQ is the value of Z at time 1=0. By substituting the model specifications into the approximate solution equation, we obtain the following equations for each of the three cases.

0.157 t + 4 7.28 t + 4 44, Ot+4 Figure 8 shows that from time 1 = 0 to t
= 5[s] The initial water level is the reference point (
0) is shown. In Case 1, the amplitude is large and the rate of attenuation is slow, whereas in Cases 2 and 3, the amplitude is small and the rate of attenuation is very fast, showing a remarkable difference.

According to the present embodiment, as shown in the table of FIG. 3, as a countermeasure against overshoot due to liquid vibration, a design margin of about 12% is required, whereas in the conventional example, a design margin of 100% is required. In addition, the time it takes for the liquid to decay to less than 5% of the final steady state is 2.2 seconds, compared to the long period of 400 seconds in the conventional case.
, can be reduced to an almost negligible value of two seconds.

In this way, by simply installing the flow resistor 2 with a simple orifice 3 structure inside the U-shaped tube 1, the extension ratio of the end of the U-shaped tube 1 can be suppressed as much as possible as a countermeasure against overshoot, and the U-shaped tube 1 can be
It is effective in shortening the length of the tube 1.

〔Effect of the invention〕

According to the present invention, the size of the U-shaped pipe used to discharge drain water can be halved, so that the workability of the filter unit to which the U-shaped pipe is connected can be greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a side view of an embodiment of the present invention, FIG. 2 is a side view of a conventional example, FIG. 3 is a diagram showing fluctuations in the water level of seal water, and FIG.
Figure 5 and Figure 5 are explanatory diagrams of the workability of U-shaped pipes, Figure 6 is an explanatory diagram of conventional problems when checking the water level of seal water inside the U-shaped pipe, and Figure 7 is an explanatory diagram of the problem of conventional problems when checking the water level of seal water in the U-shaped pipe. Figure 8 is a graph showing water level fluctuations in three analysis cases. 1... U-shaped tube, 2... Flow resistor, 3... Orifice. Figure 1? Figure 32 Figure 6 Figure 4 Cause Figure 5 Figure 7

Claims (1)

[Scope of Claims] 1. A U-shaped pipe structure for discharging drain water, characterized in that a flow resistor consisting of an orifice or the like is installed at or near the lower end of the U-shaped pipe.