KR101635916B1

KR101635916B1 - Boiler-on and continuous steam blowing method in a thermal power plant

Info

Publication number: KR101635916B1
Application number: KR1020150051521A
Authority: KR
Inventors: 강경완; 김동웅
Original assignee: 한국남동발전 주식회사
Priority date: 2015-04-13
Filing date: 2015-04-13
Publication date: 2016-07-04

Abstract

According to the present invention, a continuous steam washing method for a boiler of a thermoelectric power plant comprises: a step of igniting a boiler and performing a temperature and pressure increasing process to secure a steam temperature and a steam pressure in a steam washing pipe required for steam washing; a step of opening a valve for preheating a temporary steam washing pipe to preheat a temporary pipe installed to discharge washing steam to the outside before reaching a steam turbine; a step of maintaining ignition of the boiler, using a boiler water supply pump for supplying water to the boiler from a fresh water storage tank via an economizer and a boiler circulation pump for recirculating boiler water separated from a separation storage tank into which wet steam flows from the boiler to the boiler to adjust a flow at an entrance of the economizer while operating the boiler circulation pump, blocking a boiler water recirculation valve formed on a pipeline on a discharge side of the boiler circulation pump immediately before steam washing to separate a recirculation flow, and increasing a supply amount of the boiler water supply pump while blocking the boiler water recirculation valve to maintain a rated flow at the entrance of the economizer; a step of opening a boiler water relief valve for discharging the boiler water separated from the separation storage tank immediately before steam washing by the boiler circulation pump to the outside; and a step of opening a valve installed on the steam washing pipe to perform steam washing.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a boiler-

The present invention relates to a boiler continuous steam cleaning method for a thermal power plant, and more particularly to a boiler continuous steam cleaning method in an operating state without extinguishing the boiler in a thermal power plant.

Generally, when a generator is newly installed in a thermal power plant, foreign substances such as welding residues may remain in the pipe of the boiler. If the foreign matter is left in the pipe and the operation for generating electricity is performed, Since the steam is in a state of high temperature and high pressure, the turbine blades are damaged by the welding residues in the piping or the power generation efficiency is lowered.

Therefore, in order to prevent such a problem, a boiler steam cleaning is performed by installing a new generator in a thermal power plant. The boiler steam cleaning is a main commissioning procedure to prevent damages and efficiency deterioration of the turbine blades and the like as described above by removing foreign substances in the piping.

In the steam cleaning process of the conventional power plant boiler, as shown in FIG. 1, the boiler is ignited and the steam washing pipe is subjected to a temperature rising and pressure increasing process to secure the steam pressure and temperature necessary for the steam washing. At this time, the water supplied from the inflow boiler at low load (usually under 30% load) does not evaporate once through, so the boiler is separated from the separator storage tank into which the humidifier is introduced. (BCP) to the boiler circulation pump (BCP). If the water storage tank level is excessively low, the boiler circulation pump (BCP) is stopped. Digested. Then, the steam cleaning is performed while the boiler is extinguished, and the process of igniting the boiler is repeated.

Therefore, in the steam cleaning process of the existing power plant boiler, it is impossible to control the level of the separated storage tank due to the pressure drop when discharging the steam. The boiler circulation pump (BCP) is stopped and the boiler is extinguished. In fact. Accordingly, there has been a problem that the steam cleaning start-up process and cost are increased by performing steam cleaning in the boiler-extinguished state.

It is therefore an object of the present invention to provide a boiler continuous steam cleaning method which can be performed in an operating state without extinguishing a boiler of a thermal power plant.

The boiler continuous steam cleaning method of a thermal power plant according to the present invention includes the steps of performing a temperature raising and pressure raising process for igniting a boiler, securing the pressure and temperature of steam in a steam washing pipe to a steam pressure and a temperature required for steam washing, A step of preheating the piping to be installed to open the piping preheating valve so that the washing steam is discharged to the outside before the steam turbine, and a step of maintaining the ignition of the boiler, A boiler feed pump for feeding water from a fresh water storage tank to a boiler through a carbon burner and a boiler circulation pump for controlling the flow rate of the feeder inlet while maintaining the operation of the boiler circulation pump for recycling the boiler water separated from the boiler to the boiler A boil circulation pump for generating a boil, Isolating the recirculation flow by shutting off the rupture recirculation valve and increasing the feed rate of the boiler feedwater pump with interception of the boiler water recirculation valve to maintain the scraper inlet flow rate at the rated flow rate, Opening the boiler water relief valve for discharging the boiler water separated by the boiler circulation pump to the outside, and performing a steam cleaning by opening a valve installed in the steam washing pipe. .

In addition, in the step of performing the steam cleaning, the boiler water relief valve is shut off according to the full opening of the valve installed in the steam washing pipe, and when the level of the separated storage tank is excessively increased during the steam cleaning, So that the level of the separated storage tank is adjusted.

Therefore, according to the boiler continuous steam cleaning method of the present invention, the continuous steam cleaning is performed in the operating state without extinguishing the boiler of the thermal power plant, thereby shortening the process of steam cleaning and improving the efficiency of steam cleaning, .

1 is a flowchart showing a steam cleaning process of a conventional thermal power plant boiler,
2 is a schematic diagram for a boiler continuous steam cleaning process according to the present invention,
3 is a flow chart illustrating a boiler continuous steam cleaning process in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a boiler continuous steam cleaning method for a thermal power plant according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a schematic diagram for a boiler continuous steam cleaning process in accordance with the present invention, and FIG. 3 is a flow diagram for a boiler continuous steam cleaning process in accordance with the present invention.

Referring to FIGS. 2 and 3, the boiler continuous steam cleaning method of a thermal power plant according to the present invention will be described. First, the boiler 30 is ignited, and the steam 55 is shut off from the steam washing pipe 50. Pressure and temperature to ensure the pressure and temperature of the steam required for steam cleaning.

The water supply process in the boiler 30 is supplied to a fresh water storage tank 10 through a raw water tank, a pure water tank and a plurality of storage tanks 10 as shown in FIG. 2, Water is supplied to the silk screening machine 20 first through the water feed pump 15. The economizer 20 is a device for preheating the boiler feed water and preheats the boiler feed water by heat exchange from the boiler exhaust gas. Thus, it is preheated in the absorbent unit 20 and then supplied to the water pipe 35 in the boiler 30. The boiler water separated from the separate storage tank 40 into which the humid air flows from the boiler is recycled to the boiler 30 by the boiler circulation pump (BCP) 70.

And a step of preheating the pipe 60 by opening a bypass valve 65 for steam washing as a preheating step of the pipe is performed. The steam pipe 60 is temporarily installed to allow the steam to be discharged to the outside before the steam turbine (not shown). In the steam washing process, the steam introduced from the steam washing pipe 50 is supplied to the high- If the high-temperature and high-pressure washing steam suddenly flows into the piping 60, which is in a cooled state, the piping may be expanded. In order to prevent this, the piping 60 is preheated before the present process.

In this way, the steam washing causes the pipe preheating valve 65 to open to allow some of the steam to flow into the pipe 60, thereby preheating the pipe 60. The boiler 30 is kept in the boil- And maintains the operating state of the pump 70. Fig.

Then, the boiler circulation pump 70 and the boiler feed pump 15 adjust the flow rate of the cutlery inlet 25, and a boiler water recirculation valve (not shown) formed in the discharge side pipeline of the boiler circulation pump 70 90) to isolate the recirculated flow rate. The disconnection of the boiler water recirculation valve 90 formed in the duct between the boiler circulation pump 70 and the cutlery 20 is achieved by cutting off the boiler water recirculation valve 90 immediately before the steam rinsing to isolate the recirculated flow rate, It is possible to prevent swelling (sudden fluctuation of level due to pressure fluctuation) due to pressure fluctuation and inability to control the level of the separating and storing tank 40.

At the same time as the boiler water recirculation valve 90 is shut off, the feed rate of the boiler feedwater pump 15 is increased to maintain the flow rate of the raker inlet 25 at the rated flow rate.

Then, the boiler water relief valve 75 is opened just before the steam cleaning. The boiler water relief valve 75 is connected to the boiler water circulation pump 70 to discharge the boiler water separated from the separation storage tank 40 to the outside by the boiler water circulation pump 70, Level control to open the boiler water relief valve 75 immediately prior to the steam wash to prevent a sudden increase in the level of the isolated storage tank 40 during steam cleaning. On the other hand, the valve 80 is an auxiliary relief valve for backing up the boiler water relief valve 75 like the boiler water relief valve 75. In this step, the boiler water relief valve 75 is normally controlled A quick opening is performed to control the level.

Then, the shut-off valve 55 installed in the steam washing pipe 50 is opened for a predetermined time to perform the steam washing for the pipe washing. The valve 55 installed in the steam washing pipe 50 is used as the motor drive valve and at this stage the boiler water relief valve 75 is shut off in accordance with the full opening of the valve 55 installed in the steam washing pipe 50. And, when the level of the separate storage tank 40 is excessively increased during the steam washing, the boiler water relief valve 75 is opened and adjusted.

The test piece is provided on the discharge side of the pipe 60 to check the foreign substance discharged by the steam cleaning. The test piece is a test piece made of a copper plate material After confirming the surface condition, check the test piece, and if the decision is passed, replace the test piece and repeat the procedure from the temperature increase and pressure increase process, and perform forced cooling once a day.

Table 1 shows the result of applying the boiler continuous steam cleaning method according to the present invention having the above-described structure to a real thermal power plant.

division OO Firepower # 3
(Conventional method) OO Firepower # 4
(Conventional method) OO Firepower # 5
(Invention) Number of steam wash days 12.5 14 8 Total number of steam washes 107 80 125 Washing cycle 120 min / s 15 to 30 minutes / time Coal consumption / times 20 tons / times 15 tons / times Water consumption / times 210 tons / s 140 tons / times BFR (blowing force ratio) 1.74 1.81 2.1

Table 1 shows the number of days of steam cleaning, the total number of times, the amount of coal used, and the amount of water used by applying the steam cleaning method according to the present invention to an actual OO thermal power plant in comparison with existing methods. As a result of applying the invention to a thermal power plant, the BFR (Blowing Force Ratio) increased by 16% p compared to conventional steam cleaning procedures.

In addition, the number of process days was shortened by 6 days and the cost was reduced by about 2.1 billion compared to the OO 4 thermal power plant (see Table 2).

division Coal (ton) Pure (ton) Power (MWh) Air (days) system Savings 433 15,930 1,877 6 - Amount (Wbn) 0.4 0.2 2.1 18 21

In addition, the number of starting times of the boiler circulation pump is reduced, and the service life of the high-voltage electric motor is additionally increased.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken as limitations Changes and modifications will be possible.

10: Fresh water storage tank 20:
30: boiler 35: boiler water pipe
40: Separate storage tank 50: Steam cleaning piping
55: valve 60:
65: Steam cleaning valve for preheating piping 70: Boiler water circulation pump

Claims

A boiler steam cleaning method for a thermal power plant,
Performing a heating and boosting process to ignite the boiler and to secure the pressure and temperature of the steam in the steam washing pipe to the steam pressure and temperature necessary for the steam washing,
Preheating the piping to be installed to open the piping preheating valve so that the scrubbing steam is discharged to the outside before the steam turbine,
For maintaining the ignition of the boiler and for maintaining the operation of the boiler circulation pump for recirculating the boiler water separated from the separate storage tank into which the humid air is introduced from the boiler to the boiler, from the fresh water storage tank to the boiler The boiler water feed pump and the boiler circulation pump are used to control the flow rate of the absorbent inlet and to isolate the recirculated flow rate by blocking the boiler water recirculation valve formed in the discharge side pipeline of the boiler circulation pump immediately before the steam washing, Increasing the feed rate of the boiler feedwater pump with the interruption of the recirculation valve to maintain the raker inlet flow rate at the rated flow rate,
Opening a boiler water relief valve for discharging the boiler water separated by the boiler circulation pump from the separation storage tank immediately before the steam washing,
And performing a steam cleaning by opening a valve installed in the steam washing pipe.

The method according to claim 1,
Wherein the boiler water relief valve in the step of performing the steam washing is shut off in accordance with the full opening of the valve installed in the steam washing pipe.

3. The method of claim 2,
Wherein the boil water relief valve is opened to adjust the level of the separated storage tank when the level of the separated storage tank excessively increases during the steam cleaning in the step of performing the steam washing.