1-Clarifier (HRSCC) outlet pH is 1 to 1.5 units lesser than
inlet pH or out let pH is 10 to 15% lesser than inlet pH
2-Clarifier outlet water conductivity increases by 115 to 125%
than its inlet water conductivity
3-Hardness of water at clarifier outlet decreases slightly
(1 to 3 ppm) than its inlet water
4-Losses in clarifier = Inlet water X 2%
5-Detention time in clarifier =The time it takes for a drop
of water to travel from inlet to outlet
Detention time = Clarifier tank volume M3 / Flow rate M3/day
Actually clarifiers are designed for detention time for 3 to 4 hours. If
clarifier inlet flow increases detention time reduces & vice versa
6-For
reverse osmosis
- Permeate water pH=Inlet water pH X 80-85%
- Permeate water conductivity =Inlet water conductivity X 5-15%
- Reject water pH =Inlet water pH X 105 to 110%
- Reject water conductivity = Inlet water conductivity X 325 to 350%
7-Pressure drop in RO cartridge filter will be 0.1 to 0.2
kg/cm2
Water treatment plant chemicals & their functions
Water treatment plant chemicals & their functions
8-RO membrane pores opening will be 0.0001 microns
9-UF membranes pores opening will be 0.01 to 0.1 microns
10-Ro plant recovery rate = (Feed water flow-Reject water
flow) X 100 / Feed water
11-Salt passage in RO = Concentration in permeate water X
100 / Concentration in feed water
12-Salt rejection in RO = (1-Salt passage) X 100
13-In a RO plant reaction
time for chemicals is minimum 15-20 seconds, so dosing taps should be at least
20 meter before the RO unit (RO inlet line)
14-For SAC: Outlet water pH = Inlet water pH X 70-75%
15-For SAC: Outlet water conductivity = Inlet water
conductivity X 130-150%
16-For SBA: Outlet water pH = Inlet water pH X 140-150%
17-Feed water or Boiler water TDS = Conductivity X 50-60%
18-Standard pressure drop in DM plant vessels (SAC, SBA,
MB etc) is 0.4 to 0.6 kg/cm2
19-Pressure drop in UF membranes is 0.1 to 0.3 kg/cm2
20-Whatman paper required for SDI is of cellulose nitrate
membrane having pore size 0.45 microns & 47 mm diameter
21-Colloidal silica is in un-dissolved form & non
reactive, it is removed in clarifier
22-Reactive silica is in dissolved form, is removed in
RO, SBA & MB
23-A change of 1 pH value represents the change of 10
times in relative acidity or alkalinity.
For example: pH 4 is 10 times acidic than pH 5
24-Higher pH of water causes scaling & lower pH
causes corrosion
25-Acids & alkalis have tendencies of increasing or
decreasing the conductivity of water
For example: Water of pH 10 has more conductivity than
that of pH 7
26-In DM plant SBA is always kept after SAC:
The cat ion resin is usually
located before the anion resin. If the water contains any hardness traces, then
it reacts with OH- of anion resin forming Hydroxide. And hydroxide has less
solubility; it precipitates in the alkali environment.
27-For DM plant if DM plant
Degasser is provided if inlet water has bicarbonates > 150 ppm, if it is
less then there is no necessary of degasser tower.
28-On every 1 degree rise in
water temperature its conductivity increases by 4 to 5 micS/cm
29-M alkalinity should be
less than 20% of TDS
30-Silica in drum water =
0.4 X OH alkalinity
31-2 X P-M = 0 or negative,
indicates no hardness in water
32-Conductivity = 6 X PO4
in drum water
33-Standard parameters of
water in steam drum at various operating pressure
Sl No.
|
Parameter
|
UOM
|
P = up to 35 Kg/cm2
|
P=35-45 kg/cm2
|
P = 45-67 Kg/cm2
|
P =67-100 kg/cm2
|
P = >100 kg/cm2
|
1
|
pH in
drum
|
9.5-10.2
|
9.5-10.2
|
9.5-10.2
|
9.5-9.8
|
9.5-9.8
|
|
2
|
Conductivity
in drum
|
MicS/cm
|
500
|
250
|
150
|
100
|
50
|
3
|
TDS
in drum
|
ppm
|
250
|
125
|
75
|
50
|
25
|
4
|
Hardness
in drum
|
ppm
|
Nil
|
Nil
|
N
|
N
|
N
|
5
|
Silica
in drum
|
ppm
|
<15
|
<10
|
<5
|
<1
|
<0.6
|
6
|
Chloride
in drum
|
ppm
|
Nil
|
Nil
|
Nil
|
Nil
|
Nil
|
7
|
Oil
& Grease in drum
|
ppm
|
Nil
|
Nil
|
Nil
|
Nil
|
Nil
|
8
|
Hydrazine
(N2H4) in feed water
|
ppm
|
0.01-0.2
|
0.01-0.2
|
0.01-0.2
|
0.01-0.2
|
0.01-0.1
|
8
|
Residual
phosphate in drum
|
ppm
|
18-20
|
15-18
|
10-15
|
6-10
|
5-7
|
34-Standard parameters of feed water/Condensate water
Sl No.
|
Parameters
|
UOM
|
Values
|
1
|
pH
|
8.5-8.8
|
|
2
|
Conductivity
|
MicS/cm
|
3-5
|
3
|
TDS
|
ppm
|
1.5-2
|
4
|
Hardness
|
ppm
|
Nil
|
5
|
Silica
|
ppm
|
0.02
|
6
|
Chloride
|
ppm
|
Nil
|
7
|
Oil
& Grease
|
ppm
|
Nil
|
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ReplyDeletewhy low pressure boiler (Without super heater or process boiler ) has high TDS value and without dosing in drum, it is possible to increase TDS in drum?
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