JP3540512B2 - Ice plug forming equipment for vertical pipes - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technique for inspecting and repairing a piping system in various plants and the like, and more particularly to an apparatus for cooling a pipe to form an ice plug or an ice plug therein.
[0002]
[Prior art]
In various plants, when there is a need to repair or replace auxiliary equipment such as instrumentation pipes and cooling water pipes, which are branch pipes connected to high flow main pipes or vessels, etc., stop operation of the plant For the purpose of carrying out the repair without any problem, an ice plug method has been implemented to fluidly separate the repaired portion from the main pipe or the like. This is to cool the outer surface of the branch pipe near the repaired part, freeze the liquid inside the pipe, and cut off the flow of fluid, and the block of ice formed by the freezing acts as a plug. So called. Ice plugs have the function of a mechanical shut-off valve.However, for example, in order to shut off the fluid flow and prevent the liquid from flowing into the repair part, it is necessary to arrange a large number of The structure is complicated and the cost is large. On the other hand, the ice plug method is very useful because a plug having a function of a shutoff valve can be formed at an arbitrary position in the pipe only by partially cooling the pipe, and the plug is not melted.
The general construction method of such an ice plug method will be described with reference to FIG. 4. A cooling jacket 63 is attached to a branch pipe 61. The cooling jacket 63 sandwiches the branch pipe 61 between two semicircular tubular casings, and forms a closed flow passage through which a cooling medium flows. Liquid nitrogen is supplied into the cooling jacket 63 from a liquid nitrogen cylinder 65 through a conduit 67 to cool and freeze the liquid inside the branch pipe 61. The nitrogen gas that has been heated and vaporized is collected in the collection container 71 through the conduit 69.
[0003]
[Problems to be solved by the invention]
Thus, when the branch pipe or pipe for forming the ice plug is a so-called vertical pipe extending in the vertical direction and connected to a main pipe or container below, the internal fluid of the main pipe or the like is used as a heat source. Works. That is, when the branch pipe is cooled to form an ice plug, the cooled part becomes low in temperature. However, when the operation of the plant is continued, the liquid inside the main pipe and the like is maintained in the operating state, so Remains hot. In such a state, the low-temperature liquid in the vertical cooled pipe descends to the main pipe, and the high-temperature liquid in the main pipe rises to generate natural convection. When such natural convection occurs, heat is successively carried into the part to be cooled by the rising liquid flow, so that the temperature of the liquid in the part to be cooled decreases slowly, and it takes a long time to form ice plugs. . For this reason, there is a problem that the preparation time for the repair work is lengthened, the repair takes a long time, and the consumption of liquid nitrogen required for forming the ice plug becomes excessive.
Accordingly, an object of the present invention is to provide an ice plug forming apparatus for a vertical pipe which can form an ice plug in a short time with a small consumption of liquid nitrogen even when a pipe on which an ice plug is to be formed is a vertical pipe. And
[0004]
[Means for Solving the Problems]
To solve the problems According to the process 30, according to the present invention, the first cooling jacket is also heat pipe located below apparatus for forming ice plugs in a vertical tube communicating with the container, which is attached to the vertical tube a cooling device comprising a precooling device including a second cooling jacket to be mounted in a vertical pipe in the heat source pipe nearer than the first cooling jacket, the vertical tube between said first and second cooling jacket A temperature monitoring device including a temperature detection terminal for detecting a temperature; and means for operating the pre-cooling device so that the detected temperature is maintained at about 4 ° C. at which the specific gravity of water is maximized. You. It is desirable that the cooling device be started slightly after the pre-cooling device.
[0005]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. First, referring to FIG. 1, a branch pipe 3 extends upward from a main pipe 1 through which hot water flows. Since the branch pipe 3 extends upward, a so-called vertical pipe and an apparatus for forming an ice plug therein will be described. The main cooling device 10 includes a cooling jacket 11 attached around the branch pipe 3 and a cooling source 13 connected to the cooling jacket 11 via a conduit. The cold heat source 13 is, for example, a liquid nitrogen supply source. As shown in FIG. 2, the cooling jacket 11 is provided with semi-cylindrical casings 15 and 17 opposed to each other with the branch pipe 3 interposed therebetween, and its axial flanges 19 and 21 are fastened and fixed by bolts 23 and nuts 24. It is configured. As shown in FIG. 3, a packing 22 is interposed between the flanges 19 and 21, and the boss portions 25 and 27 of the casings 15 and 17 are filled with a gland packing 29, so that the inside of the casings 15 and 17 is filled. A closed passage 31 for liquid nitrogen is formed in contact with the outer surface of the branch pipe 3. The gland packing 29 is supported from outside by a packing holder 35 supported by a tightening bolt 33. By adjusting the tightening length of the tightening bolt 33, an appropriate packing pressure can be obtained.
An inlet nozzle 37 and an outlet nozzle 39 are attached to one casing 17, and a liquid nitrogen introduction pipe 41 and a nitrogen gas outlet pipe 43 are connected to each of them. Then, the liquid nitrogen flowing into the closed flow path 31 from the introduction pipe 41 flows in contact with the outer surface of the branch pipe 3 and cools it. Nitrogen vaporized by removing the heat of the branch pipe 3 and water in the branch pipe 3 flows out of the outlet pipe 43 and returns to the cold heat source 13.
[0006]
Referring again to FIG. 1, the branch pipe 3 is surrounded by a cooling jacket 51 of the pre-cooling device 50 near the main pipe 1. The mechanical structure of the cooling jacket 51 is almost the same as the cooling jacket 11 described above, and the cooling source 53 is the same as the cooling source 13. Further, the functions and functions thereof are almost the same as those of the cooling jacket 11 of the cooling device 10 except that the temperature of the cooling water is about 4 degrees Celsius. A thermocouple 56, which is a temperature detecting terminal, is disposed on the branch pipe 3 sandwiched between the cooling jackets 11 and 51, and is connected to a temperature monitoring device 57 via a lead wire. It can be monitored.
[0007]
According to the ice plug forming apparatus having the above-described configuration, the pre-cooling device 50 cools the temperature of the water inside the branch pipe 3 to which the cooling jacket 51 is attached to about 4 ° C. Then, natural convection occurs between the branch pipe 3 which is a vertical pipe and the main pipe 1 as shown by an arrow in FIG. 1, and the upward flow stops at this portion. This is because the specific gravity of water becomes maximum at about 4 ° C. Incidentally, it cooled or activated precooling device 50 simultaneously parallel, or by the cooling device 10 was started delayed slightly inside water branch pipes 3 until forming ice plugs of sufficient intensity. Temperature monitoring device 57, by a thermocouple 56 to monitor the internal temperature of the adjacent portion of the ice plug formation portion, if the temperature exceeds about 4 ° C., the information on the operator to operate the pre-cooling device 50 provide.
[0008]
【The invention's effect】
As described above, according to the present invention, a portion where the ice plug is formed since the isolated from the convection generation section by precooling device, thermal transport from the main tube by convection is prevented by the cooling device, a vertical tube Even a good quality ice plug can be formed. Since the pre-cooling device only cools to about 4 ° C. instead of the freezing point, it does not require a large cooling capacity. Therefore, it is necessary to minimize the required energy as a whole compared to a conventional ice plug forming device having no pre-cooling device. And an ice plug can be formed in a short time from the start .
[Brief description of the drawings]
FIG. 1 is a system diagram showing an overall structure of an embodiment of the present invention.
FIG. 2 is a partially cutaway side view showing the partial structure of FIG. 1;
FIG. 3 is a plan sectional view taken along the line III-III in FIG. 2;
FIG. 4 is an overall conceptual diagram of a conventional device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Main pipe 3 Branch pipe 10 Cooling device 11 Cooling jacket 13 Cold heat source 15, 17 Casing 19, 21 Flange 22 Packing 23 Bolt 24 Nut 25, 27 Boss part 29 Gland packing 31 Sealed flow path 33 Tightening bolt 35 Packing presser 37 Inlet nozzle 39 Outlet nozzle 41 Inlet tube 43 Outlet tube 50 Pre-cooling device 51 Cooling jacket 53 Cold heat source 56 Thermocouple 57 Temperature monitoring device

Claims (2)

An apparatus for forming ice plugs in a vertical tube heat pipe or communicating with the container positioned below, and a cooling device including a first cooling jacket is attached to the vertical pipe, more the said first cooling jacket temperature comprising a precooling device including a second cooling jacket to be mounted in a vertical pipe in the heat source pipe closer, the temperature detection terminal for detecting the temperature of the vertical tube between said first and second cooling jacket An ice plug formation for a vertical tube, comprising: a monitoring device; and means for operating a pre-cooling device such that the detected temperature is maintained at about 4 ° C. at which the specific gravity of water is maximized. apparatus. The apparatus for forming an ice plug for a vertical pipe according to claim 1 , wherein the cooling device is started slightly after the precooling device.

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