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

VALVES

Gate Valve:

                                    gate valves are designed to isolate flow.this type of valve has two useful position,fully open and fully closed. if the gates is left half opened an eddy is formed behing its disk and cause the valve to vibrate. The gate valve introduces a small pressure drop.

                                                                   GATE VALVE

Rising stem gate valve:

                                  In this the  stem is not connected directly to the handwheel.

Non-risisng stem gate valve:

                                          In a non-rising stem gate valve the stem is connected directly to the handwheel.


Globe Valve: 

                                        They are designed to throttle or regulate flow. The disc can be placed in many different positions between fully open and fully closed. Pressure drop in this valve is large because the fluid passes through a restricted opening and changes direction several times.

 

globe valve               

why cooker cooks the food quickly?

As we know that boiling point is directly proportional to the atmospheric pressure,if the external pressure increased the boiling point of water will also be raised. This is done in closed container or pressure cooker from where the vapours are not allowed to escape,hence they develop more vapour pressure within the cooker and thus the boiling point of water increase and cooks the food quickly.

 

why evaporation causes cooling?

After the collision between molecules some molecules acquire higher energy,then molecules of higher energy escape in air in the form of vapours. The kinetic energy of remaining molecules decreases.the temperature will also falls, hence cooling is caused.

Cloud And Pour Point

 Cold weather performance of diesel fuel is a key consideration for users. Actual specifications for cold flow properties are based on expected temperature extremes and different test methods are used in different parts of the world. In the United States cloud point is used as an indicator of the cold flow properties of the fuel. Cloud point is the temperature at which wax begins to precipitate out of the fuel. The longer paraffin molecules in the fuel precipitate as a wax when the temperature falls below the cloud point. This wax clogs unheated fuel lines
and filters. The more paraffinic a fuel the higher will be its cloud point. In some parts of the world, pour point is used as an indication of the lowest temperature at which a fuel can be pumped. Pour points are generally 4–5◦C lower than the cloud point.

Distillation

The distillation range of diesel fuel has a significant influence on engine performance. This is especially so in medium and high speed engines. If the fuel is too volatile the engine loses power and efficiency because of vapor lock in the fuel system or poor droplet penetration into the cylinder. On the other hand if the volatility of the fuel is too low, the engine will lose power and efficiency as a result of poor atomization of the fuel. Both the front end and the back end of the distillation are important. If the 10 %vol point is too high, the engine will have difficulty starting. A low 50% point reduces particulate emissions and odor. Because heavier molecules are more difficult to burn, both soot and the soluble organic fraction (SOF) of the particulate emissions are increased if the 90% point is too high, the emission of unburned hydrocarbons will also increase.