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This is the most preferred BOE Preparation Book.

Being a power plant engineer one should read this Book at least once ,This book covers Boiler,Turbine,D.M Plant, CHP & Efficiency calculation.

POWER PLANT INTERVIEW QUESTIONS & ANSWERS

       Process diagram of DM plant

Reservoir:-Reservoir is used for water storage purpose. Water is taken from here for dm water process work.
High Rate Solid Contact Clarifier:-
This clarifier is a high rate, solid contact, sludge re-circulation type clarifier, which is minimum time and space and using a minimum amount of Chemicals, Produces an effluent of the highest quality. it is used principally for clarification, lime softening, silica reduction, or organics reductions of water and waste water containing suspended solids, color and organic impurities. As such, it provides a means for chemical addition and mixing, Flocculation and up flow clarification in a single unit.
MULTI GRADE FILTER (MGF):- It consists  of vertical or horizontal pressure filters that contain multiple layer of coarse fine sand.It reduce turbudity and TSS (<5 PPM) from water. water is passed through multi layers of filter media consisting graded sand, pebbles and gravels layers. The contaminants in the water are captured in the media bed and filtered water passes into the discharge manifold at the bottom of the tanks. The next and last step is back washing, a process of effectively removal of captured contaminants from the media bed. After back-washing the filter is rinsed with raw water and after the required quality of water is achieved the filter is put back into service.
Ultra filter (UF):- It will remove oil, grease, and colloidal silica particles from water. It has membrane system range from 0.01 to 0.1 micron. UF consists of  Hollow Fiber Membranes are Hot Water, Chlorine & Acid/Alkali Tolerant. These Membranes have the unique advantage of being hydrophilic nature, which results in fouling resistance. UF Membranes also have a wide range of pH and temperature tolerance and are easily backwash able, to avoid membrane fouling.
RO system:-  here two different concentrations are separated by a semi-permeable membrane. Osmotic pressure drives water through the membrane; the water dilutes the more concentrated solution, and the end result is equilibrium.In RO  systems, hydraulic pressure is applied to the concentrated solution to counteract the osmotic pressure. Pure water is driven from the concentrated solution at a flow rate proportional to applied pressure and collated downstream of the membrane. 
Degasser:- Degasser is an integral part of any demineralization plant, where it is generally placed between cation and anion exchanges and removes Carbon Dioxide, which is generated by dissociation of carbonic acid at cation outlet water. In this Degassing processes, Degasser Tower is utilized, which is made from either FRP or Mild Steel with rubber lined or epoxy coating. Low air pressure is generated at the bottom of the tower that drives out CO2 and the degassed water is collected in a sump beneath the tower
MIXED BED UNITS:- After passing water through cation then anion exchanger it is passed through mixed bed unit. In mixed bed cation and anion resins are mixed and while water passes through it as it passes through thousands of cation/anions exchanger ‘resulting final effluent of very
good quality water. It is similar to conventional ion exchanger a cylindrical steel vessel. Internally rubber lined containing resin bed above which there is free space to allow expansion of resin when back washed. In addition to the usual distributors, a mixed bed is fitted with a centre distribution and collection system. At the time of regeneration the bed is back washed. This expands the resin bed and allows the heavy cation resin to sink to bottom and lighter anion resin rises to top. After some time when back wash is stopped the resins settle without upsetting the separation. There is a well defined interface between the cation and anion resin bed and that interface is just at the level of centre distributors. Anion resin can be regeneration with caustic an rinsed. Spend caustic solution and rinse water can be withdrawn through the centre distributors. After this cation resin can be regenerated and rinsed. In that case caustic will now be acid inlet/rinse water inlet. When both the resins are regenerated and rinsed the excess water is drained down to the surface of the bed and the resins are mixed thoroughly, with the help of air blowing. The air is blown in through bottom distributors and out through the air release at the top. After proper mixing the space above the bed is filled from above and unit is put into final rinse.​​

​​​​​​​what is D.M (Demineralization) plant and it’s process diagram?
      In power plant  water is known as the heart of the plant, so it is most necessary to supply salt free water  for process. The demineralization is the process of removing mineral salts from water by using ion exchange process.  The D.M water reduces the scale formation, Deposition and corrosion of tubes. It increases the life of pipes and tubes in plant. It prevents the deposition of minerals in turbine blades. It removes Mineral salts in the form of cations such as sodium, calcium, iron, copper and anions such as chloride, sulphate , nitrate etc. 
SOURCES OF WATER
There are  3 types of sources of water-

  1. Surface water    ---- River water,lake water, pond water ect.
  2. Ground water  ---- Bore water, well water.
  3. Sea water        ---- Sea water.
Rain water is the purist of all sources of water. since the water having unique property of absorbing every thing on the earth that is why water is called universal solution. As the rain water falls on the earth it will be exposed with several gases present in the atmosphere, after falling on the earth water will be flows through several salts& minerals on the earth. In this way water is getting contaminated.
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DM PLANT QUESTION AND ANSWERS

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