JPH0421555B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Fields of Industrial Application] The technology for transporting slurry is used in a wide variety of ways, such as metal surface treatment, factory wastewater sludge treatment, and civil engineering fields. The present invention relates to a slurry piping flushing method for avoiding clogging of the piping when the slurry feeding is stopped.

[Conventional technology]

FIG. 2 is an example of a conventional slurry feeding piping system. Normally, the piping line for slurry transportation consists of a slurry tank 11, a slurry feed pump 12, a tank source valve 13, and a flushing water supply valve 14, as shown in Figure 2. It is usually installed with a rising slope.

During slurry feeding, when the slurry feeding pump 12 is stopped, the slurry begins to flow back toward the slurry tank 11, and the liquid level in the slurry tank 11 becomes H, which becomes Δh higher than the liquid level height h during transportation. Further, the slurry in the pressure-feeding side piping of the slurry liquid-feeding pump 12 also stays up to this level H. Then, sedimentation of the slurry begins in the pipe, and the height K of the slurry after sedimentation can be expressed by the following equation.

K = HC / 100 H; Slurry tank liquid level C; Slurry concentration (volume %) In the conventional slurry pipe flushing method, when the slurry feed pump 12 is stopped, the precipitation occurs and the pipe is not clogged. For flushing, the tank main valve 13 is closed, and then the flushing water supply valve 14 is immediately opened, water is supplied into the pipe, and the slurry liquid is diluted with water and discharged from the end of the pressure pipe to the outside of the system for cleaning. It was hot.

Normally, this method was sufficient when the slurry concentration was 10 to 30% by volume.

[Problem that the invention seeks to solve]

However, in recent years there has been a trend to use highly concentrated slurries, and in the high concentration range of 30 to 80%, conventional methods can no longer be used. That is, when the slurry concentration is 30 to 80%, significant accumulation occurs in the housing of the slurry pump and in the piping before and after the pump, and the following difficulties have arisen in the conventional method.

That is, the flushing operation after the slurry pump is stopped, that is, the operation of closing the tank main valve 13 and opening the flushing water supply valve 14 to supply water into the piping, must be performed in an extremely short time. This operation must be completed before slurry precipitation begins and deposition ends. These are influenced by physical properties such as the diameter and true specific gravity of the slurry particles, but according to our experiments, when the particle diameter is 80 μm and the true specific gravity is 4.0, it is necessary to carry out the above operation within two minutes. For this reason, conventional ways of thinking and operating cannot be used.

Another disadvantage is that the amount of water that must be supplied for flushing is large. This supply water is usually sent to a slurry tank or discharged outside the system as wastewater, but in the former case there is a problem that the slurry concentration of the entire system changes significantly, and in the latter case, there is a burden on wastewater treatment. The disadvantage is that it becomes large.

In particular, in a slurry delivery system installed in a production facility designed for continuous production, these difficulties become extremely serious problems from the viewpoint of productivity. The present invention solves these problems in the conventional methods described above, and provides a method that enables efficient pipe flushing in an extremely short time, using a small amount of water, and having a small effect on slurry concentration and a small burden on wastewater treatment. It is something.

[Means for solving problems]

The gist of the present invention is that when handling high concentration slurry,
The purpose is to automatically and promptly discharge the slurry in the piping to the outside of the system by a stop signal when the operation of the slurry liquid feeding pump is stopped.

In other words, in a piping system flushing method in which highly concentrated slurry is transferred from a slurry tank using a slurry feed pump, when the operation of the slurry feed pump is stopped, the stop signal automatically causes the slurry to flow out from the slurry tank. This slurry piping flushing method is characterized in that the slurry in the piping system is immediately drained out of the system by stopping the system, and then the inside of the piping system is washed with flushing water.

In the present invention, high concentration slurry is about 30% by volume.
~80%.

A stop signal when the operation of the slurry liquid feeding pump is stopped is generally transmitted in conjunction with the motor switch of the slurry liquid feeding pump. Further, "automatically performed" means that each valve opening/closing operation is automatically performed sequentially based on the above-mentioned signal.

[Effect]

In the present invention, when the operation of the slurry liquid feeding pump is stopped, the slurry in the piping system is automatically stopped from flowing out from the slurry tank by the stop signal, and the slurry in the piping system is immediately extracted to the outside of the system. is extracted from the system with almost no precipitation.

By this operation, when the inside of the piping system is subsequently washed with flushing water, there is less slurry residue in the pipes, so the flushing work can be completed with a small amount of water and in a short time.

〔Example〕

FIG. 1 is a piping system diagram of an embodiment using the slurry piping flushing method of the present invention. 1 is a slurry tank, 2 is a slurry feed pump, 3 is a tank source valve, and 4 is a flushing water supply valve.The above is the same as the conventional method, but as an embodiment of the present invention, a slurry feed pump 2 is used. The difference from the conventional method is that a slurry removal valve 5 is provided on the suction side piping, and a liquid discharge valve 8 is provided on the pressure feeding side piping of the slurry liquid feeding pump 2.

In the flushing sequence, when the slurry feed pump 2 stops operating, the stop signal automatically closes the tank source valve 3, opens the slurry drain valve 5, and all the slurry in the pipe is transferred to the slurry receiving tank 6 with an agitator. It gets pulled out. After the drawing is completed, the slurry removal valve 5 is closed, the liquid discharge valve 8 is opened, and then the flushing water supply valve 4 is opened only for a preset time to flush the inside of the pipe.

The flushing water used for cleaning is discharged from the liquid discharge valve 8.
The slurry then enters the slurry receiving tank 6. In the slurry receiving tank 6, the highly concentrated slurry discharged from the piping is mixed with a stirrer, but after being diluted to 5% or less with the flush water used for cleaning, it is sent to the slurry pump 7. The slurry is then returned to slurry tank 1. In this case, since the concentration is sufficiently low, there is no need to flush the pipe from the slurry receiving tank 6 to the slurry tank 1a.

With this method, flushing of the slurry piping in a high-concentration slurry feeding system is performed by sequential signals starting from the liquid feeding pump stop signal to the tank source valve 3a, slurry drain valve 5, flushing water supply valve 4a, and liquid discharge valve 8.
The slurry in the pipe is first extracted by operating the
After that, the slurry piping can be cleaned efficiently and fully automatically using a small amount of water. After flushing is completed, the liquid discharge valve 8 is closed to prepare for the next operation.

A secondary advantage of the present invention is that the slurry liquid extracted from the pipes is diluted to 5% or less with flushing water that has been used to clean the pipes, and then returned to the original slurry tank. It may be possible to eliminate wastewater treatment.

〔Effect of the invention〕

According to the method of the present invention, even slurry in a slurry delivery pipe having a slurry concentration of 50% or more can be extracted within a very short period of time, and the amount of flushing water used is small, so that cleaning can be accomplished easily, quickly, and thoroughly. In addition, the influence of cleaning water on slurry concentration is small,
Moreover, wastewater treatment of washing water can also be made unnecessary.
In addition, unmanned operation became possible because it was completely automated using a sequence including a stop signal for the liquid pump. Furthermore, in the past, there were cases where the slurry concentration had to be kept below 20-30% due to the difficulty of pipe flushing, but with the present invention, it has been possible to reduce the slurry concentration to 30-30%.
The industrial contribution is extremely large, as it allows easy use of slurry with a high concentration of 80%.

[Brief explanation of drawings]

FIG. 1 is a piping system diagram of an embodiment of the slurry piping flushing method of the present invention, and FIG. 2 is a piping system diagram of an embodiment of the conventional slurry piping flushing method. 1, 11... Slurry tank, 2, 12... Slurry liquid feeding pump, 3, 13... Tank source valve,
4, 14...Flushing water supply valve, 5...
... Slurry removal valve, 6 ... Slurry receiving tank, 7 ... Slurry pump, 8 ... Liquid discharge valve, H ... Slurry tank liquid level, K ... Slurry accumulation height in slurry piping.

Claims (1)

[Claims] 1 In a piping system flushing method in which highly concentrated slurry is transferred from a slurry tank using a slurry feed pump, when the operation of the slurry feed pump is stopped, the stop signal automatically prevents the slurry from flowing out from the slurry tank. A slurry piping flushing method characterized in that the slurry in the piping system is stopped, the slurry inside the piping system is quickly extracted to the outside of the system, and the inside of the piping system is then washed with flushing water.