Applied science Sem 1 UNIT 1

UNIT 1 : Water & Fuel and their Classification

Easy notes

Q1. Explain determination of hardness of water by EDTA method with respect to following points:
principle , structure of metal EDTA complex.

Principle:

EDTA (Ethylenediaminetetraacetic acid) reacts with calcium (Ca^2+) and magnesium (Mg^2+) ions in water to form stable complexes. This reaction helps measure water hardness.

Structure of Metal-EDTA Complex:

EDTA acts like a claw, forming a strong bond with the metal ions (Ca^2+ or Mg^2+). The resulting complex is stable.

[Procedure: (to make answer big for marks)

1. Water sample is titrated with EDTA solution.

2. The endpoint, marked by a color change using an indicator, shows when all calcium and magnesium ions are bound by EDTA.

3. The volume of EDTA used helps calculate the concentration of calcium and magnesium, indicating water hardness.]

 

 

Q2) Define Priming and Foaming. Give causes, disadvantages and preventions of priming and foaming.

1. Priming:

• Definition: Rapid steam production in a boiler may carry water droplets, creating 'wet' steam, a phenomenon known as priming.
• Causes:
1. Excessive water level in the boiler.
2. Excessive foam.
3. High steam generation speed.
4. Faulty boiler design.
• Disadvantages:
1. Difficult to judge the actual water column height due to foaming.
2. Salts from droplets reduce machinery lifespan.

2. Foaming:

• Definition: Formation of continuous foam or bubbles on the water surface in a boiler.
• Causes:
1. High concentration of dissolved salts in boiler-feed water.
2. Presence of oil droplets and alkali in boiler-feed water.
3. Agitation of boiler-feed water.
• Disadvantage:

1.    Leads to wet steam formation.

In summary, priming and foaming often occur together in boilers, causing issues like difficulty in water level judgment, salt damage to machinery, and the formation of wet steam. Priming is mainly influenced by water level, foam, steam speed, and boiler design, while foaming is linked to dissolved salts, oil, alkali, and aggressive water agitation.

 

 

 

 

Q3) Define
a. GCV
b. NCV
Write relation between GCV and NCV

a. Gross Calorific Value (GCV):

• Definition: GCV is the total heat obtained from burning a unit mass of solid or liquid fuel or unit volume of gaseous fuel (at STP) and cooling the products of combustion to 15°C. Also known as the higher calorific value.
• Key Points: Measures total heat released on complete combustion.

b. Net Calorific Value (NCV):

• Definition: NCV is the heat obtained from burning a unit mass of solid or liquid fuel or unit volume of gaseous fuel (at STP) where the products of combustion escape with some heat. Also known as the lower calorific value.
• Key Points: Measures heat obtained when combustion products are allowed to escape.

c. Relation between GCV and NCV:

Where 'h' is the percentage of hydrogen in the fuel.
It should be noted that the unit of latent heat of water and unit of G.C.V., N.C.V. should be same.

 

 

 

 

Q4) 50 ml of a water sample requires 12.7 ml of 0.02 m EDTA during titration. Calculate total hardness of the water.

 

 

Q5) Explain Proximate analysis of coal.

Definition: Proximate analysis of coal involves determining four key components in a coal sample:

1. Moisture %
• Principle: All moisture in coal evaporates when heated at 110°C for 1 hour.
• Method: Weigh a powdered, air-dried coal sample, heat it at 110°C for 1 hour, and measure the weight loss.
• Formula:
  
  
2. Volatile Matter %
• Principle: At 925°C, coal molecules thermally degrade to produce volatile matter.
• Method: Heat the moisture-free coal from the first experiment at 925°C, measure the weight loss.
• Formula:
  
  
3. Ash %
• Principle: Inorganic matter in coal oxidizes to form non-combustible ash.
• Method: Burn the residual coal from previous experiments, weigh the ash.
• Formula:
  
  
4. Fixed Carbon %
• Calculation: Actual carbon available for combustion after loss of volatile matter.
• Formula: Fixed Carbon % = 100−(Moisture % + Volatile Matter % +Ash %)