power plant engineering

VAPOUR ABSORPTION MACHINES (VAM):         The vapour absorption machines are becoming popular. The vapour compression machines use secondary energy in the form of electricity which is normally costly and these machines use CFC based refrigerant which may cause environmental pollutions like warming up or ozone depletion. On account of power shortage, and with increasing availability of natural gas the vapour absorption machines are becoming popular and attractive. The absorption system uses lithium bromide as absorbent and water as refrigerant. The machines are available with dual fired boilers so that they can be operated by using high speed diesel in emergencies when there is a disruption in the gas supply. These machines have no moving parts and are thus noiseless and vibration less. The maintenance costs are negligible as compared to vapour compression machines. Various options are available with single stage, two stage , parallel flow and series flow machines ...

Molecular Weight :            2.016 Density :                             0.0898 gms / liter Solubility :                          Slightly soluble in alcohol.                          1.82 % soluble in water. Hazardous Characteristics : Explosive Limit in Air, percent ( V / V ) :           Upper Explosive Limit (UEL) :       74.2 %           Lower Explosive Limit (LEL) :       4.0 % Explosive Limit in Oxygen, percent ( V / V ) :           Upper Explosive Limit (UEL) :          94.0 %      ...

Rating of transformer:       Transformers are generally specified with Apparent power rating rather than active power rating due to following reasons:  Reason (1) : Rating of a transformer depends upon temperature rise which depends upon the losses taking place in the Transformer. The temperature can be maintained within permissible limits by using proper cooling system. M ore the effectiveness of cooling system more will be the rating of transformer. For a given cooling system rating of any electrical machine is indirectly determined by the losses present in the machine In a transformer      Constant losses depends on the voltage rating      Variable Losses depend upon current rating      Total losses depends upon v and I ratings ∴ Transformer rating is in terms of v*I which is called as Apparent power rating Reason (2) : During manufacture stage of the transformer, the manufacturer...

        There is a physical law which states that the solubility of any gas in a liquid is directly proportional to the partial pressure of the gas above the liquid surface. Another law states that the solubility of a gas in a liquid decreases with an increase in temperature of the liquid. These principles are employed in the operation of Deaerator.         A Deaerator utilizes steam by spraying the incoming water into an atmosphere of steam in the pre-heater section (1st stage). It then mixes this water with fresh incoming steam in the Deaerator section (2 nd stage).

         The  function  of  the  Deaerator is  to  remove  dissolved non-condensable gases and to heat boiler feed water. It consists of a pressure  vessel  in which water and steam are mixed  in  a  con­trolled  manner. When this occurs, water temperature  rises,  and all non-condensable dissolved gases are liberated and removed and the effluent  water  may be considered corrosion  free  from  an oxygen or carbon dioxide stand point. Free air  or other  non-condensable gases should be vented prior permitting the fluid  to enter the Deaerator.         Deaerator protects the feed pumps, piping, boiler and any other piece  of equipment that is in the boiler feed and  return  cycle from the effects of corrosive gases i.e. oxygen and carbon  dioxide, to a level where they are no longer a corrosion fa...