JPS629797B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is designed to prevent dust generated due to rust on the inner surface of a conduit from scattering inside the conduit due to, for example, an increase in gas flow rate, a change in pressure, or a change in the flow direction. In addition, in order to prevent problems that may occur during transportation, such as blockage of combustion equipment nozzles connected to the pipe, failure of meters, or adverse effects on combustibility, the inner surface of the pipe is moistened and dust is removed. The present invention relates to a method for wetting the inside of a gas conduit in order to prevent the deposition of gas.

This type of dust scattering prevention method has been known for some time.
A method in which the inner surface of the pipe is brushed and washed with liquid; ○B A method in which the pipe is once filled with liquid and retained therein to become wet, and then the remaining liquid is collected; ○C A method in which the liquid (mainly paraffinic mineral oil) is misted. There is a method of moistening the inner surface of the pipe by blowing it into the pipe using a gas such as city gas or propane gas as a carrier, but method ○B is highly effective in preventing dust from scattering. When carrying out this work, especially when underground pipes are targeted, large-scale excavation work and ancillary construction work are involved, which makes the work extremely difficult, for example, in densely populated residential areas or public road surfaces. Depending on the surrounding environment, it may not be possible to apply it, or even if it can be applied, it has the disadvantage of causing a huge loss in terms of efficiency and economy. Compared to this, methods ○B and ○C do not involve large-scale excavation work or incidental work, and are more advantageous than method ○B in terms of construction. It has the following drawbacks:

In other words, although the liquid filling method (○) is superior in terms of wetting effect, it is not possible to completely recover the remaining liquid in the pipe, so there is a risk of problems in the gas supply function after construction. In addition, in the method of ○C, it is difficult to judge the reach distance of the fog, making the wetting effect area unclear, and the amount of liquid adhering to the inner surface of the tube also varies depending on the distance from the fog scattering point. The spray tends to be quite non-uniform, and in addition, the amount of spray is limited depending on the flow rate of the carrier gas, which tends to result in insufficient wetting effect and lack of durability. In order to ensure that the amount of spray is sufficient, or if the amount of spray becomes excessive due to the flow rate of the carrier gas, it may be necessary to There was a risk of side effects such as clogging the nozzle.

The present invention has been made in view of the above circumstances, and
The purpose of this invention is to provide a method for wetting gas pipes that is easy and efficient to install, yet achieves a reliable, sufficient, and durable wetting effect, and avoids side effects after implementation. It is characterized in that bubbles generated from a mixture of water, oil, and surfactant are introduced into the gas pipe and transported along the inner surface of the pipe.

That is, since the method of the present invention involves introducing and transporting foam into a pipe, in terms of construction,
As in the case of ○C mentioned above, there is no need for large-scale excavation work or incidental construction work, and it can be carried out easily and efficiently regardless of the surrounding environment, but the object to be transferred within the pipe is foam. From, gas pressure 100
It is possible to transport the foam over a sufficient distance under a low pressure of about mmH ₂ O, and it also transports the bubbles along the entire inner surface of the tube while thoroughly moistening the dust that adheres there. Therefore, there are no side effects such as dust scattering problems and nozzle clogging during implementation, or adverse effects on combustibility after implementation, which were observed in the above-mentioned fogging method, and it can be used in the desired section. A reliable, sufficient and durable wetting effect can be achieved. On top of that,
As the foam disappears after use, the volume significantly decreases and it becomes a liquid, making post-processing such as extraction from the pipe easy.Moreover, the moisture in the residual liquid gradually evaporates and it flows together with the gas. It provides a secondary wetting effect to the dust in the downstream pipe, increasing the sustainability of the wetting effect, and the liquid after water evaporates is oily and surfactant, which is more viscous than water. Since it adheres to the inner surface of the pipe in the form of a film, it has a double or triple effect of helping to prevent new rust from forming.

In addition, when carrying out the method of the present invention, there are pipe joints in the implementation section, but if a swellable sealant such as hemp or jute is used as a sealant for the pipe joints, it will be possible to prevent moisture due to foam. Since the sealing material gradually expands, it can also be expected to improve the airtightness of the joint.

Examples of the method of the present invention will be described below with reference to the drawings.

The pressure inside the gas conduit 3 in the section to be implemented extending between the adjacent valves 1 and 2 is reduced using, for example, a governor installed in that section.

A mixture of paraffinic mineral oil, water, and a surfactant is stored in a foaming device 4, and the flowing gas in the conduit taken out from the upstream side of one of the valves 1 is fed into the foaming device 4 at an appropriate flow rate (pressure). ) Bubbles are generated by introducing through a mesh and bubbling under controlled conditions.

The generated bubbles are once introduced into the receiver 5 to remove excess liquid and gas by the gas-liquid weight separation effect, and then only the bubbles are sent into the pressure reducing pipe downstream of the valve 1. By moving this toward the other valve 2 side along the inner surface of the tube, the dust adhering to the inner surface of the tube is successively wetted. In this case, the pressure inside the pipe is monitored using the pressure reduction side of the downstream valve 2 or a governor or water intake pipe in the middle, and if necessary, purge is performed using the purge machine 6 to reduce the pressure inside the pipe to a low pressure. This promotes the movement of bubbles.

Once the conduit 3 in the target section is filled with bubbles, leave it as it is for a certain period of time to achieve sufficient moisture, and then open the valve 1 to supply gas into the section to blow out the bubbles and eliminate the foam. We aim to promote this.

After defoaming, the remaining liquid is extracted through a water intake pipe to an extent that does not interfere with gas flow.

Finally, by opening both valves 1 and 2, the pressure inside the conduit 3 in the target section is restored and the gas flows normally, thereby completing the work for the unit section.

In the drawing, 7 is a replenishment tank for the mixed liquid, and 8 is a purge machine, and these, the foaming device 4, the receiver 5, the purge machine 6, etc. are carried together by a transport vehicle 9 such as a truck. It is configured so that it can be transported to the site.

In addition, it is most preferable to use the flowing gas in the conduit as the foaming means of the foaming device 4 necessary for carrying out the method of the present invention, but when the target is a conduit where the required foaming pressure cannot be obtained. Needless to say, a special foaming pressure fluid is used.

[Brief explanation of the drawing]

The drawing is an overall operational schematic diagram illustrating an embodiment of the method for wetting the inside of a gas conduit according to the present invention.

Claims (1)

[Claims] 1. A method for wetting the inside of a gas conduit, characterized by introducing bubbles generated from a liquid mixture of water, oil, and a surfactant into the gas conduit, and transporting them along the inner surface of the tube.