Troubleshooting of Demin Plant

8/13/2019 Troubleshooting of Demin Plant

1/8

Troubleshooting of DM plant

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Defects Causes Remedies

Decrease in capacity betweentwo successive regenerations

a. Increase in ionic load

b. Flow recorder defective

c. Insufficient chemicals used

d. Resin dirty

e. Plant being used intermittently

f. Channelling in bed

g.Resin fouled

h.Resin deteriorated

i. Resin quantity insufficient in unit

Check by analysis

Check

Check

Give prolonged backwash

void this

Check and ensure uniformdistribution !collection

If cation" give #Cl wash$ if anion" resin

give alkaline brine treatment

Check and replace charge

Check and top up
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2/8

Treated quality not upto thestandard

a. Cation e%hausted

b. nion e%hausted

c. &i%ed bed e%hausted

d. &' resin not in uniform mi%ed state

e. (ome valves like backwash leaking

f. )a slip from cation high

g. (i*+ slip from anion high

h. ,nit idle

i. ,nit not sufficiently rinsed

-. %cessive!low flow rate

k. Channelling

l. Resin fouled

m.

Resin deteriorated

Check

Check

Check

Repeat air mi% and rinse

Check

Check raw water analysis$ change in)a!/ and (i*+!/ ratio$ use morechemicals

Check raw water analysis$ change in)a!/ and (i*+!/ ratio$ use morechemicals

Check

Rinse to satisfactory quality

d-ust to between unit min!ma% flowrate

Check and ensure uniformcollection!distribution

Check resin and give alkaline brine!#C0 treatment

Check resin and replace


3/8

Mixed bed quality not good a. Resin not separated during backwash properly

b. ir mi% not proper

c. Final rinse not proper

d. (ome valves may be leaking and contaminatingthe treated water

Give e%tended backwash aftere%hausting the bed

Repeat

Repeat

Check and e%amine

High residual C! fromdegasser

a. It can be due to choked suction filter of degasserair blower

b. Improper air flow to the degasser

c. 1egasser blower not in operation

d. ir seal not fitted!broken resulting in shortcirculating of air

Check and clean filter

Check damper" speed of blower"

discharge pressure

Check and operate blower

Check and replace fitting


4/8

"nit rinse ta#es long time a. Flow rate too high

b. ,nit e%hausted

c. 'ackwash valve passing

d. nion resin organically fouled

e. &' air mi% not satisfactory

f. cid!alkali pockets formed in unit

Increase flow rate

Regenerate unit

Check and rectify

Give alkaline brine treatment

Carry out air mi% once again

Faulty design check and rectify./emporarily backwash 2followed by airscour if &'3 and rinse again

$low rate too less a. Choked valve and suction strainer of pump

b. Cavitation in the pump

c. 0ow inlet pressure

d. 1istribution or collecting system choked

e. Resin trap at outlet choked

f. Control valve shut due to low off4take

Check

Check

Check4pump

Check

Check and clean

Increase off4take


5/8

%ressure drop across the bedincreasing day by day

a. 1efective valves

b. Packed resin bed and resin fines present

c. Collecting system choked

d. Pressure gauge defective

Check

Give e%tended backwash with openmanhole and scrap off fines from topsurface of the resin

Check" repeat backwash

Check and rectify! replace

$looding in degasser a. 5ery high air flow rate

b. Packed tower chocked due to dirt or broken

packing material

Reduce air flow rate by ad-ustingdamper

*pen and check

Resin being lost a. %cessive backwash pressure

b. Faulty collecting system

c. Inlet strainer damaged

Check inlet pressure and reduce if

necessary

%amine same for breakage

Check and replace


6/8

&'ector not wor#ing a. 0ow power water pressure

b. ir lock in the unit

c. Choked or defective valves

d. -ector no66le may be choked

e. /oo much back pressure from the unit

f. 'ulge in pipe lining

Check

'ackwash 7 open air release

%amine and rectify

Check

Check for chokage of collectingsystem$ passage of inlet!outlet valves

Check and rectify

(ncorrect reading rota)meters

a. Chocked orifice lines!orifice

b. 1irty glass and float

Check and clean

check and clean

(mproper reading from flowrecorder integrator

a. Choked impulse lines!orifice

b. 1P transmitter requires recalibration

c. 0eakage in signal tube between transmitter andpanel

d. 0ow air pressure for 1P transmitter or recorder

Check and clean

Recalibrate

Check

Check


7/8

*evel electrodes system formeasuring and dilution tan#

not functioning properly

a. Improper contact between electrodes and controlcabling

b. (horting of the two electrodes due to moisture orany foreign material

c. Improper working of the level controllers

Check contact and rectify

Check and dry the contacts of moistureand dirt

Check

*ea#age from acidin'ection+unloading+transferpumps

a. Improper ad-ustment of the mechanical seal

b. 0ow strength of sulphuric and presence of ferroussulphate

Check and ad-ust

Check concentration and takeappropriate action

Corrosion in concentrated

acid tan#s and lines

a. 0ow concentration of sulphuric acid

b. 0ining of #Cl tank!pipe line damaged

Check silica gel breather in acid

storage tank and replace silica gelcharge if e%hausted

Rectify

(mproper opening andclosing of pneumatically

operated valves

a. 1efective solenoid valves

b. 0eakage in airline from solenoid valve to the

respective control valve.

c. Improper contact of micro switch giving falseindication to panel

d. Fused mimic lamp giving false indication to thepanel

Check

Check

Check

Check


8/8

(mproper operation of acertain regeneration cycle

a. 1efective relays in the control circuit Check and replace relays

,olid state programme notfunctioning properly

a. /he controller can be kept in 8hold8 due to thereasons e%plained under operation

b. Improper operation of the controls for thecontroller

c. 1efect in the inside of the controller

Remove conditions which cause 8hold8of controller

Press test switch 7 check the completecycle

Check the instruments thoroughly frominside. &eanwhile" operation may becontinued by using bypass toggle

switches