VAPOURIZATION

 "Vapourization of an element or compound is phase transaction from liquid or solid phase to gas phase."

There are three types of vapourization.

1. Evaporation
2. Boiling
3. Sublimation

1.Evaporation:

                       Evaporation is a phase transition from liquid to gas phase at temperature below the boiling temperature. Evaporation usually occurs on surface.

2.Boiling:

              Boiling is a phase transition from liquid to gas phase that occurs at or above the boiling temperature.

Boiling occurs on surface.

3.Sublimation:

                     Sublimation is the transition of a substance from solid to gas phase without passing through an intermediate liquid phase.the reverse process of sublimation is called deposition.formation of frost is example of meterological depositon.

METHODS FOR REMOVAL OF IMPURITIES OF WATER

Removal of physical impurites:

                                              There are several methods for the removal of physical impurities of water some methods are as follows.

• Screening 
• Sedimentation or settling 
• Coagulation
• Filteration
• Reverse osmosis 

 Screening: 

                   In screening process water is passed through screens or series of screens which results in removal of floating metals.

Sedimentation or settling:

                                               Waste particles are removed by the action of gravity. Gravity causes most of the suspended coarse particles such as clay,sand,bacteria to fall to the bottom of the sedimentation or settling tank from there they are removed.

 

                                           SEDIMENTATION TANK


Co-Agulation:

                            Such particles take longer time to settle to remove such particles coagulant is added. Coagulant is a chemical that combines with the smaller particles in water to form large particles.Most commonly coagulatnt is Alum.

                                              COAGULATION


Filteration:

                         In filteration water is passed through sand filters which results in removal of clay, sand also bacteria.there are two types of sand filters.

                                                FILTERATION
 
a.Gravity filters:

                                        Generally used for munciple water treatment and to less extent for industrial water treatment.In tank consisting of layers of fine sand,coarse and gravel,raw water  enters from one part of tank leaving sand on gravity filter from the top and clean water is taken from the bottom .Working period is 24 hrs.

b.Pressure filters:

                             They are used for industrial water treatment, Pressure filter is the tank having raw water inlet from the top and passes through the layers of gravel and sand. Main advantage of pressure filter is that when filteration action is lowered we don't replace sand and grave.Working period is 32 hours.

HARDNESS OF WATER

Hardness:

               A water with on treatment with soap doesnot produce leather is called hardwater. Mainly hardness of water is due to salts of  Ca and Mg and other heavy metals dissolved in water.

                                  



Types of hardness:

1.  temporary hardness
2. permanent hardness

1.Temporary hardness: 

                                  It is caused by soluble bicarbonates of Ca and Mg. It is removed by boiling of water.

2.Permanent hardness:

                                 It is caused by presence of chlorides and sulphates of Ca and Mg,iron and heavy metals.It is also called noncarbonate hardness. 

Softening of water:  

                                       Process of removing hardness of water is called softening of water.

Chemicals required for removing hardness of water:

                                Ca(OH)₂ ,  Na₂CO₃

BALL VALVES AND PLUG VALVES

Ball and plug valves are designed to both isolate and throttle flow, depending on the requirements of the process.

They are used where wuick switch over from fully open to fully close or vice versa is required. These are used for fluids containing suspended solids. 

CHECK VALVES

Check valves or unidirectional valve:

                                                      Check valves are used when unidirection flow is desired. It is opened by the pressure of the fluid, whent the flow stops or tend to reverse the direction the valve automatically closes by the action of gravity. common type of check valves are lift check and swing check valves. 

 

CHECK VALVE