P&p Eng - Water Treatment

Front 1

Temporary hardness

Back 1

- Bicarbonate

-easily removed by heating water to- 100^c

-calcium bicarbonate

-magnesium bicarbonate

Front 2

Permanent Hardness

Back 2

-not easily removed

-hard scale directly on heating surface

-calcium and magnesium sulfate

-calcium and magnesium chloride

Front 3

Scale

Back 3

-caused by dissolved solids

-settled on the heating surfaces

-prevent water to absorb heat.

Front 4

1 gallon of water turns into how many gallons of steam

Back 4

1600 gallons of steam

Front 5

PH of acids

Back 5

0-7

Front 6

PH from 7-14

Back 6

basic

Front 7

what is neutral PH

Back 7

7.0

Front 8

ideal PH value for the boiler

Back 8

10.5

Front 9

treatment required for boiler water depends on

Back 9

-water source

-boiler operating pressure

(higher boiling pressuer- more pure water must be)

Front 10

surface water

Back 10

-high in suspended solids and dissolved gasses

-low in dissolved solids (exception of sea water)

Front 11

ground water

Back 11

-low in suspended solids and dissolved gasses

-high in dissolved solids (high hardness)

Front 12

treating surface water

Back 12

-high suspended solids- settling and filtration

-high dissolved gasses- additional deaeration

-low dissolved solids- less chemical type treatments

Front 13

treating ground water

Back 13

-high in dissolved solids- extensive thermal and chemical treatments

-less deaeration necessary

-little filtration

-carbon filter used for high pressure plants.

Front 14

external water treatment

Back 14

-before water enters boiler

-upto and including deaerator

Front 15

internal water treatment

Back 15

-additions of chemicals

Front 16

types of external water treatment

Back 16

-evaporating: using heat to evaporate and remove all dissolved solids

-reverse osmosis: using high pressure to force water through a membrane that removes all dissolved solids

-Deaerating: using heat to drive off gasses like o2 or co2

Front 17

types of internal water treatment

Back 17

- adding chemicals to treat water

-chemicals can be used to :

-remove residual oxygen

- remove hardness

- adjust PH

- adjust tds (total dissolved solids)

- Disperse sludge

- reduce foam

- remove scale (extreme treatment)

- protect condensate from corrosion

Front 18

clarifiers

Back 18

-used to remove suspended solids

-by allowing them to settle (by gravity)

-commonly used for river water treatment

Front 19

coagulation

Back 19

-used in conjunction with settling tanks

-remove very fine particles by causing them to come together and make a larger particle (to settle better)

-neutralizes the negative charge

Front 20

common coagulants

Back 20

aluminium sulfate - AL2 ( SO4) 3

aluminum hydroxide

sodium aluminate

Front 21

cartridge filter

Back 21

-settling tanks to remove fine particles

-use until pressure drop across unit reaches set point.

-cartridges are replaced then

Front 22

Cold Lime Soda Softening

Back 22

- remove calcium & magnesium minerals

-Lime (calcium hydroxide ca(oh)2) & soda (sodium carbonate Na2Co3) are added to the water

-chemicals reacted with hardness in the water

Front 23

Hot Lime Soda Softening

Back 23

-heating decreases the reaction time & reduce the size of the vessel required

- used for boiler feed water treatment

- sludge is formed at the bottom

-

Front 24

ion exchange water softening

Back 24

process to remove hardness forming ions and replace them with sodium or Hydrogen

Front 25

cation exchange

Back 25

- calcium and magnesium cations removed

- replaced with sodium

- calcium carbonate to sodium carbonate

-magnesium chloride to sodium chloride

Front 26

Hydrogen Zeolite softners

Back 26

-replace all cations with hydrogen

-regenerated using acid (sulfuric acid)

ex- NaCl + H2Z = Na2Z + HCl

Front 27

*demineralizers

Back 27

*2 diff resins :

- 1 resin replaces cations with h2- Cation resin

- 1 resin replaces anions with h2- anion resin

-hydrogen and hydroxide radicals combine to form water

*-cation resin is regenerated with - sulfuric acid

*-anion resin regenerated with caustic soda

Front 28

mechanical dearation

Back 28

-removal of dissolved gasses from water

steps:- divide water into small particles (heat faster)

- heat water droplets to drive off dissolved gasses

- scrub gases away from water (prevent re dissolving)

Front 29

grooving

Back 29

-CO2attack

Front 30

*deaerator controls

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- pressure: -controlled by regulating steam flow

- Level : - controlled by regulating water flow

- overflow valve for when level too high

- high and low level alarm

-temp control: -controlled by Steam pressure

- Deaeration: - controlled by manual vent on top