online assessment techniques-session 2 part 2_pptx [read-only]

8/19/2019 Online Assessment Techniques-session 2 Part 2_pptx [Read-Only]

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Online AssessmentTechni ues


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Electrostatic Precipitator Performance

Based on

Mechanical

Electrical

Operational

Maintenance

Donnerstag, 12. September

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Power System Components

1. Different Parts of power system


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Parameters

!"pical parameters that can be monitore# inclu#e$

%oltage&current

Opacit"

'as temperature

'as composition an# moisture


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olta!e"Current

olta!e and current #alues for each T$% set should &e

recorded'

ESPs are equipped with primary #olta!e and current meters on

the low$#olta!e (AC) side of the transformer

Secondary #olta!e and current meters on the hi!h$#olta!e

rectified (DC) side of the transformer.

$

control ca&inet+ these #alues can &e multiplied to estimate thepower input to the ESP.

Current times olta!e represent the num&er of watts &ein!

drawn &y the ESP and is referred to as the corona power input.

*hene#er a short term spar, occurs in a field it can &e detected

and counted &y a spar, rate meter.

+ ESPs !enerally ha#e spar, rate meters to aid in the

performance e#aluation.


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Auto olt Controller

The power input on the primary #ersus the secondary side of the T$%

set will differ

The power input on the primary #ersus the secondary side of the T$%

set will differ &ecause of the circuitry and meterin! of these #alues.

The secondary power outlet (in watts) is always less than the primary

ower in ut to the T$%.

The ratio of the secondary power to the primary power will ran!e from-. to -./ and a#era!e from -.0- to -.0


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eters

The electrical meters on the T$% ca&inets are always fluctuatin!.

2ormal spar,in! within the ESP causes these fluctuations in the

meter readin!s. These short term mo#ements of the !au!es indicate that the

automatic #olta!e controller is restorin! the ma3imum #olta!e after

shuttin! down for se#eral milliseconds to quench the spar,.

*hen recordin! #alues of the electrical data from the T$% meters it isimportant to note the ma3imum #alue that is sustained for at least a

fraction of a second


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Electrical

olta!e and current #alues for each indi#idual T$% set are useful

&ecause they inform the operators how effecti#ely each field is

operatin!.

a,e the trend charts for each field.

T$% set readin!s for current+ #olta!e+ and spar,in! rates should follow

certain atterns from the 4nlet to Outlet fields.

5or e3ample+ corona power density should increase from inlet to outletfields as the particulate matter is remo#ed from the !as stream.


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6ow electrical parameters help

!he airloa# an# gasloa# % oltagecurrent4 are the other tests, )hich

ma" be con#ucte# on irtuall" all ES5s.

6irloa# an# gasloa# cures are graphs o( the oltage 7%4 ersus the

current m64 alues obtaine# at a set con#ition test point4

!hese cures are #eelope# to ealuate ES5 per(ormance b" comparing

the graphs (rom inlet (iel# to outlet (iel# an# oer perio#s in time.

Deiation (rom the normal or preious results can in#icate that a problem

eists.


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Typical A4%$7OAD Cur#e


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6ow Air load test is done

An air$load $4 cur#e can &e !enerated with readin!s from either

primary or secondary meters.(when the ESP is new+ after the first

shutdown+ and e#ery time off$line maintenance is performed on the ESP)

The followin! procedures can &e used &y the ESP operator to de#elopan air$load cur#e.

1. Ener!i8e a de$ener!i8ed T$% set on manual control (&ut with 8ero

#olta!e and current)+ and increase the power to the T$% set manually.

9. At corona initiation the meters should suddenly :ump and the #olta!eand near 8ero current le#els should &e recorded. 4t is sometimes difficult

to identify this point precisely+ so the lowest practical #alue should &e

recorded.

;. After corona initiation is achie#ed+ increase the power atpredetermined increments &y e#ery - or 1-- milliamps of secondary

current or e#ery 1- #olts of AC primary #olta!e (the increment is

discretionary)


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Electrostatic precipitator load cur#e

=. Continue this procedure until one of the followin! occurs>

? Spar,in!

? Current limit is achie#ed? olta!e limit is achie#ed

. %epeat this procedure for each T$% set

*hen the air$load tests ha#e &een com leted for each field lot each


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field@s #olta!e"current cur#es.*hen ESPs are equipped with identical fields throu!hout+ the

cur#es for each field should &e nearly identical.

4n most cases+ the cur#es also should &e similar to those

!enerated when the unit was new+ &ut shifted sli!htly to the ri!ht dueto residual dust on the wires (or ri!id frames) and plates of older

units.

+ These cur#es should &ecome part of the permanent record of the

ESP.


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Gas-Load Curves

The !as$load $4 cur#e+ on the other hand+ is !enerated durin! the

normal operation of the process while the ESP is ener!i8ed.

+ The procedure for !eneratin! the !as$load $4 cur#e is

the same as for the air load e3cept that !as$load $4 cur#es are always

.

+ This pre#ents the upstream flow that is &ein! chec,ed from distur&in!

the $4 cur#e of the downstream field readin!s.

+Althou!h such distur&ances would &e short$li#ed (usually 9 minutes+

&ut sometimes lastin! up to 9- minutes)+ wor,in! from outlet to inlet

speeds up the process.


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as7oad Cur#e

The cur#es !enerated under !as$load conditions will &e similar to air$

load cur#es.

as load cur#es will !enerally &e shifted to the left howe#er+ &ecause

spar,in! occurs at lower

#olta!e and current when particles are present. The shape of the

cur#e will &e different for each field dependin! on the presence of

articulate matter in the as stream.


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as 7oad Air$7oad cur#e


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Daily monitorin!

Also+ !as$load cur#es #ary from day to day+ e#en minute to minute.

Cur#e positions may chan!e as a result of fluctuations in the followin!>

? Amount of dust on plates

? as flow

? Particulate chemistry loadin!

? Temperature

? es s # y

2onetheless+ they still should maintain a characteristic pattern.

as$load cur#es are normally used to isolate the cause of a

suspected pro&lem rather than &ein! used on a day$today &asis'

howe#er+ they can &e used daily if necessary.


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*hy ESP %apper Control essential

%appers

9oth oer rapping an# un#er rapping )ill #eter (rom optimal per(ormance o(

the electrostatic precipitator.

:oss o( rapper operation )ill result in poor precipitator per(ormance. Maintain operation o( the rappers.

6l)a"s chec7 on a #ail" basis4 that the rappers are operating.

.

Oer rapping )ill cause reentrainment resulting in poor ES5 per(ormance

an# high stac7 emissions.

;n#er rapping )ill cause an ecessie amount o( buil#up on the collecting

plates an# #ischarge electro#es, )hich )ill re#uce electrical po)er in the

ES5 thus resulting in poor ES5 per(ormance an# high stac7 emissions.


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4mportance of maintainin! rapper

!round straps (Earthin!)

!he complete groun#ing o( the rapper coil assembl" an# housing is

essential to complete the entire groun#ing o( the Electrostatic 5recipitator.

!he sha(t connections on the rappers are usuall" not su((icient to assurea complete groun# to the rapper coils.

properl" groun#e#, these oltages can in#uce electrical surges into controlan# po)er cables, )hich ma" #amage the controls.


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Boot seal

!his is especiall" true )ith the high oltage #ischarge electro#e rappers.

!hese rappers are isolate# b" a sha(t insulator.

6n" lea7age through this insulator )ill blee# through to the rapper coil an# it

is obious that a goo# groun# connection is re


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%apper+ Earthin!+ Boot seal


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online assessment techniques-session 2 part 2_pptx [read-only]

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