600MW机组凝结水含氧量超标的危害和预防10

600MW机组凝结水含氧量超标的危害和预防600MW

unitscondensate

oxygencontent

of

the

hazardsof

excessive

andprevention１凝结水溶解氧是化学监督的主要指标之一,特别是600M机组对凝结水溶解氧含量有更高的要求.因为溶解氧大幅度超标或长期不合格，会加速凝结水管道及设备的腐蚀，并使凝结水中含有氧化铁离子，引起电化腐蚀，使传热恶化，直至发生锅炉爆管，严重威胁机组安全、经济运行。Condensate

of

dissolved

oxygen

is

one

of

the

main

indicators

ofthe

chemical

supervision

，600MWunits

condensate

dissolvedoxygen

content

higher

dissolved

oxygen

，because

a

lot

ofexcessive

or

long

-

term

failure,

It

will

accelerate

the

condenpipeline

and

equipment

corrosion,and

make

condensat

containsiron

oxide

ions

,

causing

galvanic

corrosion，Heat

transferdeterioration

,

until

the

occurrence

of

boiler

tube

,

and

crewand

economic

operation

of

units.凝结水溶解氧存在的原因：1.真空系统不严密，进入凝结器的漏量大；2.有溶解氧含量较高的补水或回收水大量进入凝结器；Condensate

of

dissolved

oxygen

reasons

for

theexistence

:

1.vacuum

system

is

not

tight

,a

lot

of

air

to

enterthe

condenser

;

2.higher

levels

of

dissolved

oxygen

replenish

wateror

recycled

water

enter

the

condenser□针对上述原因，从以下方面进行防范和处理：

For

the

above

reasons

,

from

the

following

aspectsprevent

and

treatment

:1.真空系统的查漏

运行中真空系统的查漏以氦介质检漏为主。方法是在运行真空泵出口布置氦介质检漏装置，利用专用的喷枪在所有负压系统的阀门、法兰、管道焊缝、排大气口等处喷氦气，然后观察1-2分钟，如果检测点有泄露，检漏装置就会发出报警，泄漏量越大，报警数值就越大，即使很微量的泄露，也能检测出来。并且这种方法灵活，不受时间限制，消除漏点后随时可以检测溶解氧的变化。缺点是工作量大，耗时长。村1.vacuum

system

leak

running

vacuum

system

leak

is

mainly

helium

medium

Leak

.running

vacuum

pump

outlet

layout

the

helium

medium

leakdetection

devices

,

with

a

dedicated

gun

spray

helium

to

allnegative

pressure

system

valves,

flanges

,

pipe

welds

andexclusive

atmosphere

mouth

etc,

then

observed

for

1-2

minute

s

,

if

it

detects

some

leakage

,and

the

leak

detection

device

walarm

,

the

greater

the

amount

of

leakage

,

the

greater

thealarm

value

,

even

a

very

small

amount

of

leakage

can

bedetected

.

the

method

is

flexible

,

without

time

limit

,

aftereliminate

the

leak

，at

any

time

the

change

of

dissolved

oxygencan

be

detected

.

The

drawback

is

the

large

amount

of

work

,time-consuming

long

灌水查漏。方法是：凝结器灌水至末级叶片下100mm高度，然后查漏处理。需要注意的是灌水过程中有专人监视水位，防止水位过高进入汽轮机。但这种方法必须停机后才能进行。The

purpose

of

irrigation

leak

Condenser

irrigation

to

the

last

stage

blades

under

100mmheight

,

then

leak

to

handle

.

Should

be

noted

that

there

issomeone

to

monitor

the

water

level,in

order

to

prevent

thehigh

water

level

enter

the

turbine

in

the

irrigation

proceHowever

,

this

method

must

be

shut

down

after

.凝结水泵系统的改造凝结水泵密封水水源改为两路：闭式水和凝结泵出口自密封水。凝结水泵进口滤网顶部增加排空气管路2.Condensate

pump

system

transformationCondensate

pump

seal

water

instead

of

two

:

closedwater

and

condensate

pump

outlet

self-sealing

water

Increase

exhaust

air

line

at

the

top

of

condensate

pumpinlet

filter对加入凝结水的回收水进行处理

低加等热力系统的正常疏水。方法是维持低加正常水位，防止无水位运行或常开危急疏水运行，另外加强对疏水系统阀门法兰的检漏，尽可能减少空气的漏人

热力系统内漏进入凝结器内的非正常疏水。该疏水进入凝结器导致热负荷增加，汽阻增大，造成凝结器内空气分压的提高，从而凝结水的含氧量增加。因此查出阀门泄露并及时更换内泄阀门是一项长期的工作3

.

Join

condensate

recycled

water

treatment

normal

drain

low

pressure

heater

of

thermal

system

.

themethod

is

to

maintain

the

the

low

pressure

heater

normallevel

,

to

prevent

the

no

level

or

long-time

open

a

criticaldrain

valve

running

,

in

addition

to

strengthening

the

valveflange

leak

detection

of

drain

system

,

in

order

to

minimizeair

leakage

.

the

abnormal

drain

leakage

of

thermal

system

leak

intocondenser

.

the

drain

entering

condenser

that

heat

loadincreases,

and

the

steam

resistance

increases,

resulte

toraise

the

branch

pressure

of

air

in

the

condenser

,

and

raisthe

water

oxygen

content

of

condenser,

therefore

detectvalve

leaks

and

timely

replacement

the

leaking

valve

is

along-standing

work

.凝补水系统的改造

凝补水是除盐水。除盐水的含氧量很高，需要进行深度除氧。一般的说，凝补水直接补入热井，没有利用凝结器的真空除氧作用，除盐水补水口应接在6.9米的7、8号低加侧，经充分雾化后增大凝补水与排汽的接触面积，从而减少凝结水的含氧量。Condensate

replenishment

system

transformation

Condensate

replenishment

is

demineralized

water

,

theoxygen

content

of

demineralizing

water

is

very

high

,

it

ndepth

to

remove

oxygn

.

Condensate

replenishment

directlinto

the

hot

well

,

no

make

full

use

vacuum

removallingoxygn

role

of

condenser,

replenishment point

ofdemineralizing

water

should

pick

the

6.9

m

7,8

low

pressurheater

side

,

after

fully

atomized

to

increase

contactingof

condensate

replenishment

with

exhaust

,

thereby

reducethe

oxygen

content

of

the

condensate

.案例分析:

上海吴泾发电有限责任公司2*300MW机组运行中凝结水溶

解氧时有超标(标准控制＜30ug/L),2010年12月份#1机组进行B级检修时发现:给水泵、省煤器腐蚀严重，同时发现锅炉内部也有一定结垢和腐蚀。

经过排查发现:凝结泵自密封阀门开度小于10%时凝补水会进入凝结水中，导致凝结水含氧量升高。

另外排查发现:真空系统漏点多集中在凝结器管阀和凝结水泵入口管阀等处，空气的漏入导致凝结水含氧量升高。

上述问题解决后凝结水溶解氧合格率达到100%，平均化验值达到21ug/L.Case

Study:

Shanghai

Wujing

Power

Company

2

*

300MW

unit

:duringoperation

it

often

can

be

find

excessive

by

dissolved

oxygen

ofcondensate

(

standard

control

<

30ug

/

L).

when

#

1

unit

Btype

overhaul

:

severe

corrosion

for

the

feed

water

pumps

andeconomizer

,

at

the

same

time

find

some

scale

and

corrosioninside

the

boiler

.

After

investigation

found

:the

condensat