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1. Name four ways to deal with scale
- 1.Manage scale
- 2.Chemical addition
- 3.Remove ions
- 4.Remove water – leave solids behind
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2. LS
Lime soda softening
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7. Process that converts quick lime into Ca(OH)2
- Slaking (produces slaked lime)
- CaO + H2O --> Ca(OH)2
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8. Why not use NaOH to soften water?
It's more expensive than Lime
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9. NCH
Non carbonate hardness (permanent)
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10. CH
Carbonate hardness (temporary)
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11. If there is excess hardness, add...
Soda ash (sodium carbonate, Na2CO3)
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12. If there is excess alkalinity, add...
Calcium (e.g. CaCl2) (excess alkalinity can cause damage if it becomes carbon dioxide)
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13. Process used to remove silica
MAGOX magnesium oxide forms a magnesium hydroxide sludge blanket
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14. CL
- Cold lime softening
- Less effective 35-50 ppm
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15. WLS
- Warm lime softening
- Effective. (20-30 ppm), used when energy is available
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16. HLS
- Hot lime softening
- most effective but uses energy
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17. Historical type of ion exchange medium
Alumina silicates (zeolites)
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18. SAC
Strong acid cation exchange
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19. WAC
Weak acid cation exchange
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20. SBA
Strong base anion exchange
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21. WBA
Weak base anion exchange
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22. What kind of ion exchange is used for brine waters?
WAC
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23. Three things that can cause fouling of an ion exchange resin
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24. MBIX
Mixed bed ion exchange (cation and anion exchangers back to back)
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25. The purified water from an RO system
Permeat
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26. The waste solution from an RO, high in ions
Concentrate
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27. If the pressure spikes on a RO setup, this could mean....
The filter has been fouled and is getting plugged up
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28. Flux
The throughput, or flow rate
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29. Which requires a larger pressure: RO or nano filtration?
RO
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30. Order the three filtration methods we've covered from smallest particles filtered to largest particles filtered
- Nanofiltration
- Ultrafiltration
- Microfiltration
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31. MVC
Mechanical vapor compressor (a type of evaporation unit)
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Chemical equation for lime softening to remove calcium
Ca(HCO3)2 + Ca(OH)2 --> 2CaCO3 +2H2O
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Chemical equation for lime softeneing to remove magnesium
Mg(HCO3)2 + 2Ca(OH)2 --> 2CaCO3 + Mg(OH)2 +2H2O
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What chemical is used to improve the effectiveness of lime-soda softening?
- Sodium Aluminate (Na2Al2O4)
- (it forms a good sludge blanket)
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Why does Silica need to be removed?
- It can form hard, glassy precipitates quickly and unpredictably
- Even small amounts of scale can unbalance turbine blades and cause damage
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In a lime softener, the part of the process where the precipitate is emptied from the unit
blowdown
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The small crystals that start to form in the slow mix portion of a lime-soda softener
pin floc
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Which works in a wider range of pH?
WAC
SAC
SAC is still effective through a wide pH range
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DCS
Digital Control System
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A term for the water which does not pass through a filter
rententate
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What time of filtration is able to remove some multivalent ions?
Nano filtration
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HRSG
Heat Reused Steam Generators
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Can WAC resins be used for OTSGs (Once Through Steam Generators)?
Yes
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Can WAC resings be used for HRSGs?
No. TDS mus be 0 for Heat Reused Steam Generators
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