JP5030164B2 - Seal plug and steam pipe cleaning method using the same - Google Patents

Description

  The present invention relates to a seal plug fixed in a steam pipe and a steam pipe cleaning method using the seal plug to clean the inside of the steam pipe with a cleaning liquid.

  For example, a steam oxidation scale grows on the inner surfaces of main steam pipes and superheaters constituting the steam system of a thermal power generation system with the operation for many years. This may cause troubles such as peeling and scattering of the parts and damage of the turbine. For this reason, the steam oxidation scale is dissolved and removed by chemical cleaning.

  By the way, the steam pipe is provided with steam stop valves such as a main steam stop valve (MSV) and a reheat steam stop valve (RSV) for controlling the supply of superheated steam to the turbine. A seal ring is used as a seal member. This seal ring is a part that needs to avoid contact with the chemical cleaning liquid used in the chemical cleaning of the steam pipe. For this reason, conventionally, when performing chemical cleaning of the steam pipe, the seal ring is once removed from the steam stop valve, and after the cleaning is completed, the seal ring is re-installed in the steam stop valve and restored. An example is shown in FIG.

That is, FIG. 7 is a schematic cross-sectional view of a steam stop valve showing a conventional cleaning method. In this method, the steam stop valve 104 is disassembled, a seal ring (not shown) is removed, and then the steam stop valve 104 is attached. The temporary flange 114 is attached to close the opening, and the temporary flange 115 is attached to the seating surface of the seal ring. Then, temporary flange 114 of the steam inlet 114a of the center pipe 116 is connected to the unit and the steam stop valve 104 and the steam pipe (not shown) cleaning the pipe was connected to flow a cleaning liquid to the arrow direction in the interior of the steam stop valve 104 To clean the inside of the steam pipe.

  However, in the above method, when removing the seal ring, since it is necessary to pull out the seal ring using liquid nitrogen, there is a problem that dismantling and restoration work of the steam stop valve 104 requires a great deal of cost and time. .

  Then, the method of wash | cleaning the inside of a steam pipe is proposed, without removing a seal ring from a steam stop valve (for example, refer patent documents 1-3). An example is shown in FIG.

That is, FIG. 8 is a schematic cross-sectional view of a steam stop valve showing a conventional cleaning method. In this method, as indicated by an arrow, a chemical cleaning liquid is allowed to flow from the steam drain pipe 217 to the steam pipe 202 and at the same time, For example, the sealing water having a pressure higher by 0.2 to 0.3 MPa than the pressure of the valve flows from the pre-valve drain pipe 218 into the steam stop valve 204 so that the cleaning liquid does not flow back to the seal ring 213 side of the steam stop valve 204 I am doing so.
JP 2004-239234 A JP 2004-239234 A JP 2004-239234 A

  However, in the cleaning method shown in FIG. 8, it is necessary to continuously inject chemicals quantitatively in order to prevent the concentration of the cleaning liquid from decreasing due to the injection of sealing water. There is a problem in that costs are incurred and cleaning requires a great deal of cost.

  The present invention has been made in view of the above problems, and the object of the present invention is a seal plug that can clean a steam pipe at low cost without removing the seal ring from the steam stop valve, and steam using the same. It is to provide a method for cleaning a tube.

In order to achieve the above object, the invention according to claim 1 is a seal plug that is a part that is fixed to the inside of the steam stop valve when the inside of the steam pipe to which the steam stop valve is connected is cleaned using a cleaning liquid. Are formed in a T-shape including a first cleaning pipe fixed in the steam stop valve by a first fixing means and a second cleaning pipe, and in the steam stop valve by the second fixing means. A T-tube to be fixed, and a connecting means for connecting the T-tube and the first cleaning pipe, and the second fixing means is a base plate fixed by a magnet in the steam stop valve; It comprises a bolt threadedly inserted into a T tube, and the T tube is fixed in the steam stop valve by pressing the end of the bolt against a base plate fixed in the steam stop valve. And

  According to a second aspect of the present invention, in the first aspect of the invention, the first fixing means includes a ring-shaped elastic body inserted and held on the outer periphery of the first cleaning tube, and the elastic body from both sides. It is characterized by comprising a plate to be sandwiched, these elastic bodies, bolts inserted through the plate, and nuts screwed into the bolts.

According to a third aspect of the present invention , a first cleaning pipe fixed in the steam stop valve by the first fixing means and a second cleaning pipe are formed into a T-shape, and the second fixing means The T-tube is fixed in the steam stop valve, and a connecting means for connecting the T tube and the first cleaning pipe. The second fixing means is fixed in the steam stop valve by a magnet. And a bolt screwed and inserted into the T tube, and the end of the bolt is pressed against the base plate fixed in the steam stop valve so that the T tube is placed in the steam stop valve. As a method of cleaning the steam pipe using the cleaning plug to clean the inside of the steam pipe with the seal plug fixed to the first and second cleaning pipes of the seal plug fixed in the steam stop valve cleaning the pipe and steam pipe to the washing pipe Respectively connected to form a circulation path, characterized by washing the inside of the steam pipe by cleaning liquid flowing circulating the circulation path.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the first cleaning pipe is fixed in the steam stop valve by the first fixing means, and the T pipe is connected to the first cleaning pipe. after joined by the coupling means, characterized by inserting securing the sealing plug in the steam stop valve by fixing in the steam stop valve by the T tube the second fixing means.

According to the cleaning method of claim 3, which is performed using the seal plug according to claims 1 and 2 , the seal plug is inserted and fixed in the steam stop valve, and the first cleaning pipe and the second of the seal plug are inserted and fixed. A steam pipe and a cleaning pipe are respectively connected to the cleaning pipe to form a circulation path, and the inside of the steam pipe is cleaned with the cleaning liquid flowing through the circulation path. There is no need to remove it, and the steam pipe can be cleaned with the seal ring attached. Therefore, it is possible to perform cleaning at a low cost in a short time without requiring much cost and time for dismantling and restoration work of the steam stop valve as in the prior art.

According to the fourth aspect of the present invention, the seal plug is disassembled into the first cleaning pipe and the T pipe. First, after fixing the first cleaning pipe in the steam stop valve , the winding t is put in the steam stop valve. The seal plug can be assembled and fixed in the steam stop valve according to the procedure of inserting and connecting to the first cleaning pipe and finally fixing the T tube in the steam stop valve .

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a system diagram showing a configuration of a steam system of a thermal power generation system. Steam generated in a boiler (not shown) is superheated by a superheater 1 and then passes through a main steam pipe 2 to a high-pressure steam turbine 3. Supplied to do the required work. Here, the main steam pipe 2 is provided with a main steam stop valve (MSV) 4 for turning on / off the supply of superheated steam to the high-pressure steam turbine 3.

  Thus, the steam that has worked in the high-pressure steam turbine 3 is sent to the reheater 6 through the low-temperature reheat steam pipe 5 and is again superheated by the reheater 6, and then the high-temperature reheat steam pipe. 7 is supplied to the intermediate pressure turbine 8 to perform the required work. Here, the high-temperature reheat steam pipe 7 is provided with a reheat steam stop valve (RSV) 9 for controlling the supply of superheated steam to the intermediate pressure steam turbine 8. Although not shown, the steam that has worked in the intermediate-pressure steam turbine 8 is returned to the boiler after being condensed by a condenser (not shown), and thereafter the same operation as described above is repeated.

  By the way, when the thermal power generation system is operated for a long period of time, the steam oxidation scale grows on the inner surface of the main steam pipe 2, the superheater 1, etc. and causes various problems. Therefore, the steam oxidation scale is dissolved and removed by chemical cleaning. To be done.

  For example, when cleaning the main steam pipe 2, as shown in FIG. 1, the outlet of the superheater 1 of the main steam pipe 2 and the main steam stop valve 4 are connected by a cleaning pipe 10, and the cleaning pipe 10 and the main steam are connected. A circulation circuit (closed loop) is formed with the pipe 2, a relay tank 11 and a pump 12 are provided in the middle of the cleaning pipe 10, and the main steam pipe 2 is driven by driving the pump 12 to circulate the cleaning liquid along the circulation path. It is done to wash. In this case, it is necessary to avoid contact between a later-described seal ring 13 (see FIG. 3) provided inside the main steam stop valve 4 and the cleaning liquid, but in the present invention, the seal ring 13 is removed from the main steam stop valve 4. The present invention provides a seal plug that can clean the main steam pipe 2 at low cost without removing it, and a cleaning method using the seal plug.

  First, the structure of the seal plug according to the present invention will be described with reference to FIG.

  FIG. 2 is a partially cutaway side view of a seal plug according to the present invention. The illustrated seal plug 20 connects an outlet pipe 21 as a first cleaning pipe and a T pipe 22 by a union joint 23 as a connecting means. It is configured by

  A first fixing means 24 for fixing the outlet pipe 21 to the inside of the main steam stop valve 4 is provided on the outer periphery of the end portion of the outlet pipe 21. The first fixing means 24 includes an elastic body 25 such as a ring-shaped rubber inserted and held on the outer periphery of the outlet pipe 21, and slidably inserted and held on the outer periphery of the outlet pipe 21. Ring-shaped metal plates 26, 27 that sandwich the body 25 from both sides, a plurality of bolts 28 that pass through these metal plates 26, 27 and the elastic body 25, and a long length that is screwed into the ends of the bolts 28. A nut 29 is used.

The T tube 22 has a T-shape formed by an inlet tube 22A, which is a second cleaning tube oriented in a direction perpendicular to the outlet tube 21, and a horizontal tube 22B oriented in the same direction as the outlet tube 21. One end of the horizontal pipe 22B is connected to the outlet pipe 21 by the union joint 23. Further, a second fixing means 30 for fixing the T tube 22 inside the main steam stop valve 4 is provided at the other end of the horizontal tube 22B of the T tube 22.

  The second fixing means 30 is moved forward and backward by a base plate 32 fixed by a magnet 31 inside the main steam stop valve 4 and a disk-like flange 33 bound to the end of the horizontal pipe 22B of the T pipe 22. Each bolt 34 is configured to include a plurality of bolts 34 that are threadably inserted, and a tilting leveling foot 35 is attached to the tip of each bolt 34. The magnet 31 is attached to the center of the base plate 32 by bolts 36 and nuts 37, and a plurality of bolts 38 are threadably inserted into the outer peripheral portion of the base plate 32 so as to be able to advance and retreat. A tilting leveling foot 39 is attached to the tip of each bolt 38.

  Thus, when the main steam pipe 2 shown in FIG. 1 is cleaned, the seal plug 20 configured as described above is inserted and fixed inside the main steam stop valve 4 as shown in FIG. If the pump 12 is driven as described above in a state where the main steam pipe 2 is connected and the cleaning pipe 10 is connected to the inlet pipe 22A of the T pipe 22, the main steam pipe 2 and the cleaning pipe 10 are configured. Since the cleaning liquid circulates in the circulation path, the steam oxidation scale formed on the inner surface of the main steam pipe 2 is dissolved and removed by the cleaning liquid. In this case, in the main steam stop valve 4, as indicated by an arrow in FIG. 3, the cleaning liquid flows through the seal plug 20 and contacts the seal ring 13 assembled in the main steam stop valve 4. There is nothing to do.

As described above, in the cleaning method according to the present invention, the seal plug 20 is inserted and fixed in the main steam stop valve 4 and the cleaning liquid is circulated through the seal plug 20. It is not necessary to remove the seal ring 13 from 4, and the main steam pipe 2 can be cleaned with the seal ring 13 attached. Therefore, it is possible to perform cleaning at a low cost in a short time without requiring much cost and time for disassembling and restoring the main steam stop valve 4 as in the prior art.

  Next, a method for inserting and fixing the seal plug 20 into the main steam stop valve 4 will be described with reference to FIGS.

4 to 6 are diagrams showing the procedure for inserting and fixing the seal plug 20 into the main steam stop valve 4 in accordance with the procedure. First, when inserting and fixing the seal plug 20, as shown in FIG. The outlet pipe 21 of the plug 20 is inserted into the steam inlet 4a of the main steam stop valve 4 with the first fixing means 24 first. Then, the seal plug positioning jig 40 is fixed to the peripheral edge of the opening 4 b of the main steam stop valve 4 in a state where it is suspended vertically by a magnet 41. Here, on the outer circumference of the outlet pipe 21, pre-Me marking M1 at a predetermined position (position away x a metal plate 27) is attached, the tip position position of the sealing plug positioning jig 40 of the marking M1 The position of the outlet pipe 21 is adjusted so as to match the above.

  When the outlet pipe 21 is positioned as described above, the seal plug positioning jig 40 is removed and the nut 29 is tightened using a tool. Then, since the elastic body 25 is pinched by the metal plates 26 and 27 and expands outward in the radial direction, the elastic body 25 is in close contact with the inner peripheral surface of the steam inlet 4a of the main steam stop valve 4 and the outlet pipe. 21 is fixed.

  Next, as shown in FIG. 4, a base plate positioning jig 42 is vertically fixed by a magnet 43 on the side of the opening 4 b of the main steam stop valve 4 facing the outlet pipe 21, and attached to the tip (lower end) thereof. Marking M2 is applied to the inner peripheral surface of the main steam stop valve 4 by the marker 44. Here, the tip position of the marker 44 (the position of the marking M2) is set to a position that coincides with the axial center position of the outlet pipe 21 (a position below the main steam stop valve 4 by a distance y from the upper surface).

  As described above, when the marker M2 is marked on the inner peripheral surface of the main steam stop valve 4 by the marker 44, the base plate 32 is inserted into the main steam stop valve 4 as shown in FIG. The base plate 32 is fixed inside the main steam stop valve 4 by the magnet 31. At this time, the bolt 38 threadedly inserted into the base plate 32 is turned, and a leveling foot 39 attached to the tip of the bolt 38 comes into close contact with the inner peripheral surface 4c of the main steam stop valve 4 to securely hold the base plate 32. Here, since each leveling foot 39 can tilt, these leveling feet 39 are in close contact with the inner circumferential surface 4 c of the concave spherical surface of the main steam stop valve 4 to securely hold the base plate 32.

  Next, as shown in FIG. 6, the T tube 22 is inserted into the main steam stop valve 4. At this time, the bolt 34 is turned to draw the leveling foot 35 to the maximum. Then, the horizontal pipe 22B of the T pipe 22 is aligned with the outlet pipe 21, and both are connected by a union joint 23. Thereafter, the bolt 34 is turned to push the leveling foot 35 outward, and the end face is pushed against the base plate 32. If applied, the T tube 22 is securely fixed by the second fixing means 30, and the seal plug 20 is assembled and fixed inside the main steam stop valve 4 as shown in FIG.

  Thus, the main steam pipe 2 is connected to the outlet pipe 21 of the seal plug 20 inserted and fixed inside the main steam stop valve 4, the cleaning pipe 10 is connected to the inlet pipe 22A, and the main steam pipe 2 and the cleaning pipe are connected. 10 forms a circulation path, and if the cleaning liquid is circulated through the circulation path by driving the pump 12 shown in FIG. 1 as described above, the inside of the main steam pipe 2 is cleaned by the cleaning liquid. When the cleaning of the main steam pipe 2 is completed in this way, the seal plug 20 can be disassembled in the reverse order to the above and taken out from the main steam stop valve 4, and the operation of the thermal power generation system can be resumed.

  Although the cleaning method for the main steam pipe 2 has been described above, the high-temperature reheat steam pipe 7 can be cleaned in the same manner. In this case, the seal plug 20 is inserted and fixed inside the reheat steam stop valve 9. Is done.

It is a distribution diagram showing the composition of the steam system of a thermal power generation system. It is a partially broken side view of the seal plug according to the present invention. It is a figure which shows the washing | cleaning method of the steam pipe implemented using the seal plug which concerns on this invention. It is a figure which shows the insertion fixed point inside the steam stop valve of the seal plug which concerns on this invention. It is a figure which shows the insertion fixed point inside the steam stop valve of the seal plug which concerns on this invention. It is a figure which shows the insertion fixed point inside the steam stop valve of the seal plug which concerns on this invention. It is typical sectional drawing of the steam stop valve which shows the conventional washing | cleaning method. It is typical sectional drawing of the steam stop valve which shows the conventional washing | cleaning method.

Explanation of symbols

1 Superheater 2 Main steam pipe 3 High-pressure steam turbine 4 Main steam stop valve (MSV)
4a Steam inlet of main steam stop valve 4b Opening of main steam stop valve 4c Inner peripheral surface of main steam stop valve 5 Low temperature reheat steam pipe 6 Reheater 7 High temperature reheat steam pipe 8 Medium pressure steam turbine 9 Reheat steam Stop valve (RSV)
DESCRIPTION OF SYMBOLS 10 Cleaning piping 11 Relay tank 12 Pump 13 Seal ring 20 Seal plug 21 Outlet pipe | tube of a seal plug (1st cleaning pipe)
22 T-tube of seal plug 22A T-tube inlet tube (second cleaning tube)
22B T-tube horizontal pipe 23 Union joint (connecting means)
24 First fixing means 25 Elastic body 26, 27 Metal plate 28 Bolt 29 Nut 30 Second fixing means 31 Magnet 32 Base plate 33 Flange 34 Bolt 35 Leveling foot 36 Bolt 37 Nut 38 Bolt 39 Leveling foot 40 Seal plug positioning jig 41 Magnet 42 Base plate positioning jig 43 Magnet 44 Marker M1, M2 Marking

Claims (4)

A component that is fixed to the inside of the steam stop valve when cleaning the inside of the steam pipe to which the steam stop valve is connected using a cleaning liquid,
A first cleaning pipe fixed in the steam stop valve by the first fixing means and a second cleaning pipe form a T-shape and fixed in the steam stop valve by the second fixing means. And a connecting means for connecting the T tube and the first cleaning tube ,
The second fixing means includes a base plate fixed by a magnet in the steam stop valve and a bolt screwed into the T tube, and an end portion of the bolt is placed in the steam stop valve. A seal plug , wherein the T-tube is fixed in the steam stop valve by being pressed against a fixed base plate .   The first fixing means includes a ring-shaped elastic body that is inserted and held on the outer periphery of the first cleaning tube, a plate that sandwiches the elastic body from both sides, and a bolt that is inserted through the elastic body and the plate. The seal plug according to claim 1, further comprising a nut that is screwed onto the bolt. A first cleaning pipe fixed in the steam stop valve by the first fixing means and a second cleaning pipe form a T-shape and fixed in the steam stop valve by the second fixing means. And a connecting means for connecting the T pipe and the first cleaning pipe. The second fixing means includes a base plate fixed by a magnet in the steam stop valve, and the T pipe. A seal plug that fixes the T-tube in the steam stop valve by pressing an end of the bolt against a base plate fixed in the steam stop valve. A steam pipe cleaning method for cleaning the inside of a steam pipe using a cleaning liquid,
A steam path and a cleaning pipe are respectively connected to the first cleaning pipe and the second cleaning pipe of the seal plug fixed in the steam stop valve to form a circulation path, and the circulation path is circulated. A method of cleaning a steam pipe, wherein the inside of the steam pipe is cleaned with a flowing cleaning liquid. The first cleaning pipe is fixed in the steam stop valve by the first fixing means, and the T pipe is connected to the first cleaning pipe by the connecting means, and then the T pipe is connected to the second cleaning pipe. 4. The steam pipe cleaning method according to claim 3 , wherein the seal plug is inserted and fixed in the steam stop valve by being fixed in the steam stop valve by a fixing means.

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