JP2005214546A - Cleaning method of steam pipe and the like - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chemical cleaning method of a main steam pipe, an superheater and the like capable of inexpensively and efficiently cleaning a saturated steam pipe, the superheater and the main steam pipe without cutting. <P>SOLUTION: A pipe 11 for cleaning is pulled in a steam drum 1 through a manhole 1a of a steam drum 1. A joint pipe 10 is mounted on a tip of the pipe 11, and the joint pipe 10 is inserted into the saturated steam pipe 3. Valves 16a, 24a are closed, a valve 26a is opened, further a valve 18a is opened, and a chemical feeding pipe 19 is operated. Whereby the water is circulated in a circulation pump 13, the pipes 12, 11, the saturated steam pipe 3, the superheater 4, the main steam pipe 5, the pipes 23, 25, 26, 16, a heater 15 and a pipe 14, and the cleaning chemicals are added to the water. By continuing the circulation, the scale attached to inner faces of the saturated steam pipe 3, the superheater 4 and the main steam pipe 5 are eliminated. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method of chemically cleaning a scale grown on the inner surface of a main steam pipe or superheater such as a thermal power generation boiler using a chemical cleaning liquid.

  An example of the steam system of the thermal power generation boiler is shown in FIG. In FIG. 3, steam generated by burning fuel in a furnace 52 by a burner 51 passes through a steam drum 53, a saturated steam pipe 54, a superheater 55, a main steam pipe 56, a main steam stop valve 56a, and a high-pressure turbine. 57. Then, the steam that has worked in the high-pressure turbine 57 is sent to the reheater 59 through the low-temperature reheat steam pipe 58 and heated, and passes through the high-temperature reheat steam pipe 60 to the intermediate-pressure turbine 61 and the low-pressure turbine 62. Supplied to do work. The steam that has worked in the low-pressure turbine 62 is condensed in the condenser 63 and then returned to the furnace 52 through the deaeration pipe 64 and the boiler feed water pump 65.

  The main steam pipe 56 is connected to a drain pipe 56b having a drain valve. Although not shown, a bypass pipe is provided around the main steam stop valve 56a, and the bypass pipe is provided with a valve.

  In the steam system of such a thermal power generation boiler, a steam oxidation scale grows on the inner surface of the main steam pipe etc. with the operation for many years. Cause trouble. Therefore, these scales are dissolved and removed by chemical cleaning.

Conventionally, as a chemical cleaning method performed for such a purpose, both ends of a superheater tube or a reheater tube are cut, and a temporary cleaning pipe is connected so that a chemical cleaning liquid is applied only to a target main steam pipe or a reheat steam pipe. A method for passing liquids has been proposed (Japanese Patent Laid-Open No. 64-23096, Japanese Utility Model Laid-Open No. 4-3286).
JP-A 64-23096 Japanese Utility Model Publication No. 4-3286

  However, in such a conventional chemical cleaning method, the main steam pipe and the reheat steam pipe having a large diameter and a large pipe thickness are cut prior to the chemical cleaning, and after the cleaning, the work for restoring this is performed. This cutting and restoration requires a great deal of labor and expense, government approval and construction period.

  The present invention solves the above-mentioned conventional problems, and does not cut the saturated steam pipe, the superheater, or the main steam pipe. An object is to provide a cleaning method.

  The method for cleaning a steam pipe or the like of the present invention (Claim 1) is a method for cleaning a saturated steam pipe connected to a steam drum, a superheater connected to the saturated steam pipe, and a main steam pipe connected to the superheater. The tip of the first cleaning pipe is connected to the upstream end of the saturated steam pipe on the steam drum side from the inside of the steam drum, the second cleaning pipe is connected to the downstream end side of the main steam pipe, and the first The cleaning liquid is circulated through the saturated steam pipe, the superheater, and the main steam pipe through the cleaning pipe and the second cleaning pipe to perform cleaning.

  The method for cleaning a steam pipe or the like according to claim 2 is the method according to claim 1, wherein the main steam pipe end connected to the second cleaning pipe is a bonnet of a main steam stop valve provided in the main steam pipe; A drain pipe connected to the main steam pipe; a bypass pipe bypassing the main steam stop valve; or a pipe branched from the main steam pipe.

  The method for cleaning a steam pipe or the like according to claim 3 is the method according to claim 1 or 2, wherein a joint pipe is inserted into the upstream end of the saturated steam pipe from the steam drum and the outer periphery of the joint pipe and the inner periphery of the saturated steam pipe are Is sealed with a sealing material, and the first cleaning pipe is connected to the joint pipe.

  According to a fourth aspect of the present invention, there is provided a cleaning method for a steam pipe or the like according to the third aspect, wherein the sealing material is rubber or elastomer, and the sealing material interposed between the outer periphery of the joint pipe and the inner periphery of the saturated steam pipe is used as the saturated steam. By squeezing in the tube axis direction of the tube, the tube is expanded in the radial direction and is brought into close contact with the joint pipe and the saturated steam tube.

  In the method of the present invention, it is not necessary to cut the steam pipes to be cleaned, and each steam pipe can be cleaned at low cost and efficiently.

  Hereinafter, the present invention will be described in more detail with reference to the drawings.

  FIG. 1 is a system diagram of a main part of boiler equipment to which a cleaning method according to an embodiment of the present invention is applied, and FIG. 2 is a cross-sectional view of the steam drum taken along line II-II in FIG.

  An evaporation unit 2 such as a tube wall or a steam tube and a saturated steam tube 3 are connected to the steam drum 1. After the steam in the steam drum 1 is introduced into the superheater (in this embodiment, the primary superheater, the secondary superheater, and the tertiary superheater) 4 through the saturated steam pipe 3, and is superheated, It is sent to the turbine via the main steam pipe 5 and the main steam stop valve 6. A main steam drain pipe 7 having a drain valve 7a is connected to the main steam pipe 5. The bonnet 6a of the main steam stop valve 6 is provided with a pipe connection seat (not shown), and a later-described cleaning pipe 23 is connected to the seat.

  A cleaning pipe 11 is drawn into the steam drum 1 through the manhole 1 a of the steam drum 1. A joint pipe 10 is attached to the tip of the pipe 11, and the joint pipe 10 is inserted into the saturated steam pipe 3.

  As shown in an enlarged view in FIG. 2, a flange 40 is fixed to the tip of the joint pipe 10. An annular presser plate 41 slidable in the longitudinal direction of the pipe is fitted to the outer periphery of the joint pipe 10. A sealing material (a packing made of rubber or elastomer in this embodiment) 42 is interposed between the flange 40 and the presser plate 41.

  A plurality of bolts 44 are disposed so as to penetrate the flange 40, the seal material 42 and the presser plate 41. The head of the bolt 44 is fixed to the flange 40 by welding or the like. By tightening the nut 45 screwed into the tip of the bolt 44, the sealing material 42 is squeezed between the flange 40 and the presser plate 41 and swells in the radial direction, and the sealing material 42 becomes the inner circumference of the saturated steam pipe 3. The surface and the outer peripheral surface of the joint pipe 10 are in close contact, and the joint pipe 10 is fixed in a watertight manner. The cleaning pipe 11 is connected to the rear end of the joint pipe 10 via flanges 46 and 47.

  The pipe 11 is preferably connected to the joint pipe 10 after the joint pipe 10 is fixed to the saturated steam pipe 3, but is not limited thereto.

  This cleaning pipe 11 is connected to a pure water tank 17 through a valve 11a, a valve 30, a pipe 12, a circulation pump 13, a pipe 14, a water heating heater 15, a pipe 16 and a valve 16a. A pipe 18 for chemical injection branches from the pipe 14 and is connected to a chemical tank 20 via a valve 18 a and a chemical pump 19.

  The piping 23 connected to the bonnet 6a of the main steam stop valve 6 is connected to the cleaning drainage piping 25 through the valve 23a, the valve 33, the piping 24, and the valve 24a.

  The pipe 24 and the pipe 16 are connected via a pipe 26 having a valve 26a.

  The pipe 23 and the pipe 12 are connected via a pipe 27 having a valve 31, and the pipe 24 and the pipe 11 are connected via a pipe 28 having a valve 32.

Next, the cleaning procedure will be described.
(I) Water filling step When the saturated steam pipe 3, the superheater 4 and the main steam pipe 5 are washed, the main steam stop valve 6, the valves 7a, 26a, 31, 32, 18a are closed, and the valves 11a, 30, 33, 23a, 24a, and 16a are opened, and the circulation pump 13 is operated. Thereby, the pure water in the pure water tank 17 is circulated to the saturated steam pipe 3, the superheater 4 and the main steam pipe 5 through the pipe 16, the heater 15, and the pipes 14, 12, and 11, and the pipes 23 and 24 are also connected. Filled with this water. Air is purged from the piping 25.

(II) Chemical Solution Washing Step Thereafter, the valves 16a and 24a are closed, the valve 26a is opened, the valve 18a is opened, and the pump 13 and the chemical injection pump 19 are operated. As a result, the water circulates in the order of the circulation pump 13, the pipes 12 and 11, the saturated steam pipe 3, the superheater 4, the main steam pipe 5, the pipes 23, 24, 26 and 16, the heater 15 and the pipe 14. The cleaning chemical is added from the chemical solution tank 20 to a specified concentration. Then, by continuing the circulation in this state, the scale attached to the inner surfaces of the saturated steam pipe 3, the superheater 4, and the main steam pipe 5 is removed.

  In the step (I), the cleaning agent may be added to the water when the valve 18a is opened and the chemical pump 19 is activated to fill the saturated steam pipe 3 or the main steam pipe 5 first. .

(III) Water Flow Direction Reversing Step In the chemical solution washing step (II), the circulating water flow direction may be reversed.

  In order to reverse the circulation direction, the valves 30 and 33 may be closed and the valves 31 and 32 may be opened. Thereby, the water discharged from the circulation pump 13 to the pipe 12 flows through the pipes 27 and 23 to the main steam pipe 5, and then, the superheater 4, the saturated steam pipe 3, and the pipes 11, 28, 24, 26, 16. , 14 in order and circulates.

  The circulation direction may be switched only once, or may be switched twice or more.

(IV) Water washing step After the chemical solution washing in (II) or (III) above, the valves 16a, 30, 11a, 23a, 33, 24a are opened, the valves 26a, 18a, 31, 32, 7a are closed, and the circulation pump 13 is activated. Thereby, the pure water in the pure water tank 17 pushes out the cleaning chemical liquid remaining in the saturated steam pipe 3, the superheater 4 and the main steam pipe 5 through the pipe 25.

(V) Removal process The pipe 11 and the joint pipe 10 are cut off, the nut 45 is loosened, the joint pipe 10 is extracted from the saturated steam pipe 3, and these are carried out of the steam drum 3 to close the manhole 1a. Further, the pipe 23 is separated from the bonnet 6a, and the pipe connection seat provided on the bonnet 6a is closed with a closing plate.

  Thereby, washing | cleaning is complete | finished and boiler operation | movement restart is attained.

  According to this cleaning method, the saturated steam pipe 3, the superheater 4, and the main steam pipe 5 can be efficiently cleaned without being cut. In addition, attachment / detachment of the joint pipe 10 to the saturated steam pipe 3 can be easily performed.

  In the above embodiment, the pipe 23 is connected to the bonnet 6 a of the main steam stop valve 6, but it may be connected to the drain pipe 7. In general, a bypass pipe having a smaller diameter than the main steam pipe 5 is provided so as to bypass the main steam stop valve 6, but a pipe 23 may be connected to the bypass pipe.

It is a principal part system diagram of the boiler equipment with which the steam pipe cleaning method which concerns on embodiment of this invention was applied. It is sectional drawing which follows the II-II line of FIG. It is a boiler system diagram.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steam drum 2 Evaporating parts, such as a pipe wall and an evaporation pipe 3 Saturated steam pipe 4 Superheater 5 Main steam pipe 6 Main steam stop valve 6a Bonnet 7 Drain pipe 13 Circulation pump 15 Heater

Claims (4)

A method of cleaning a saturated steam pipe connected to a steam drum, a superheater connected to the saturated steam pipe, and a main steam pipe connected to the superheater,
Connecting the tip of the first cleaning pipe from the inside of the steam drum to the upstream end of the saturated steam pipe on the steam drum side;
A second cleaning pipe is connected to the downstream end side of the main steam pipe,
A cleaning method for a steam pipe or the like, wherein the cleaning liquid is passed through the saturated steam pipe, the superheater and the main steam pipe through the first cleaning pipe and the second cleaning pipe for cleaning. In claim 1, the main steam pipe end side to which the second cleaning pipe is connected,
A bonnet of a main steam stop valve provided in the main steam pipe;
A drain pipe connected to the main steam pipe;
A bypass pipe for bypassing the main steam stop valve; or a pipe branched from the main steam pipe; In Claim 1 or 2, the joint pipe is inserted into the upstream end of the saturated steam pipe from the steam drum, and the outer periphery of the joint pipe and the inner periphery of the saturated steam pipe are sealed with a sealing material,
A method for cleaning a steam pipe or the like, wherein the first cleaning pipe is connected to the joint pipe.   In Claim 3, the said sealing material is rubber | gum or an elastomer, and radial direction is carried out by pinching the sealing material interposed between the outer periphery of a joint pipe and the inner periphery of a saturated steam pipe in the pipe-axis direction of a saturated steam pipe. A method for cleaning a steam pipe or the like, characterized by causing the pipe to swell and closely contact with a joint pipe and a saturated steam pipe.

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