Humidification Plant Operation Methods Part 1

PLANT OPERATION

Humidification Plant

Air Washer Pump , Ducts and Trenches , Plant Location , Exhaust Air System ,
Fresh Air System

Air Washer Pump

• Automatic Pump operation ON/OFF.
• Spray water pressure should be 2 to 3 kg/cm 2.
• Use softened water.
• Air washer efficiency should be maintained at 95%.

Air washer efficiency

Spray water pressure

Automatic Water Control

• Corrosion of machine may take place with water having high and chloride contents.
• Deposition of fine dust on machines may take place with water having mineral (salt) contents.
• Corrosion of Humidification and Air Conditioning equipment's could take place with Low pH values.
• Scale formation of Humidification equipment's occurs with high contents of Calcium and Magnesium in water.
• Air washer efficiency deteriorates with high contents of certain minerals and chlorides in the water due to poor evaporation of spray water.

Air washer efficiency 

Air Water Efficiency formula:

n = DBb – Dba

     ➖➖➖➖    x 100  

      DBb – WBb        

Where

DBb = Dry Bulb Temperature of air before air washer in oC
DBa = Dry Bulb Temperature of air after air washer in oC
WBb = Wet Bulb Temperature of air before air washer in oC
n = Air washer efficiency of spray chamber in %

Water Pump Room

Limiting Parameters as guidelines for acceptable water quality of Textile Air Conditioning plant with air washers.

Parameters

• pH - 7.5 to 8.5
  
• Chlorides - 50 mg/l
  
• Sulphates - 50 to 100 mg/l
  
• Silicates - 10 mg/l
  
• Phosphates - 5 mg/l
  
• Nitrates - 30 mg/l
  
• Calcium Oxide - 120 mg/l
  
• Calcium Carbonate  - 290 mg/l
  
• Magnesium - 40 mg/l
  
• Sodium - 25 mg/l
• Iron  - 0.05 mg/l

Water Quality for the Air Washer Section

• Presently, Mill is using Raw water with average quality of 750 TDS.
• Due to rapid evaporation taking place in the air washer section, water TDS goes upto 2000 PPM with in 10 days.
• Heavy salt content in the water will deposit scale over the Eliminators, Nozzles and Wall also.
• It is not Recommended to use more TDS (above 1200 PPM ).
• It Suggested to use softened water or RO water to reduce Scale formation in the Plant room and Improve plant efficiency. 

Note : 

Above 90% means = Good

Between 80 - 85 % = Average

Below 80 % = Poor (to be improved)

Plant Location

Supply Air Plant

Exhaust Air Plant

• Supply & Exhaust Plants should be nearer to the Department.
• Supply Air Plant at first floor.
• Exhaust Fan in ground floor.
• Separate pneumafil Exhaust Trench for Spinning Frames.

Ducts and Trenches

Ducts

Ducts

Air Ducts

• Straight and Less Right angle bends.
• Not more then 120m length.
• Sufficient size.
• Proper Taper (1:100) ( Next Article we will discuss about Ducts and Trenches Briefly)  

Bends Trenche 

Straight Trenche 

Exhaust Air System

• Rotary Air filter will consume more power due to  more Resistance.
• Exhaust Trenches should be of proper in size.
• Location of the Exhaust trenches at correct place.
• Trenches are to be cleaned every week.
• Exhaust grille size and number of grilles Use Required Capacity of the Plant.
• The Exhaust Plant Room Size.
• Automatic Fan Closing sheets.
• V-Shape/Rotary Exhaust Air Filter.
• Avoid exhaust hot air leakage through the Recirculation air damper.

Air Flow Measurement

• Actual supply and exhaust plant capacity is to be measured by using Anemometer. ( Next Article we will discuss about Air Flow Measurement Briefly)  

Anemometer

HEAT-LOAD

• Required humidification plant capacity is to be calculated based on the heat load of the department. ( Next Article we will discuss about Heat Load Briefly)  

 

OPTIMISATION

• Plant capacity can be optimized by reducing the fan blade angle or by switching off the fan in multiple fan system or using inverter drives.

 
FAN POWER

Fan

• Be of Higher Efficiency.
• Have Lesser Tip Clearance.
• Be Direct Driven.
• Be with Adjustable Blades.
• Be with Automatic Fan Closing Sheets.
• Hub Ratio Should be above 30%.

P = Power (kw) varies in cube of the speed.

Q = Volume (cfm) varies as the fan speed.

P = Pressure vary as the square of the speed.

Calculation of Fan Power:

Fan Power (HP) = p x 5.2 x Q

                              -------------

                                33000       

Where

p - velocity pressure in inches of wc

q - volume of air in cu.ft / min

5.2 - constant to convert inches of wc to lbf / sq.ft

 

SUPPLY AIR SYSTEM

• Fresh Air filters are to be cleaned every 4 hours (based on requirement)
• Damper are to be cleaned and lubricated once in 15 days.
• Motors and pumps are to be cleaned daily.
• Air distribution sheets every week.
• Water spraying nozzles once in week.
• Eliminator sheets once in 3 months.
• Supply Air duct once in 15 days
• Supply Air diffusers daily.

 

EXHAUST AIR SYSTEM

• Exhaust air filter based on requirement (Min once in 4 hrs).
• Dampers cleaning and lubrication once in 15 days.
• Motors daily
• Exhaust air trenches weekly.

 

HIGHLIGHTS

SUPPLY AIR SYSTEM HIGHLIGHTS

• ATTIC ventilation will reduce transmitted heat through roof.
• False ceiling is to be insulated.
• V-shape fresh air filter.
• Sufficient size of fresh air damper will improve plant efficiency.
• Automatic fan closing sheets.
• PVC baffle type air distribution sheets.
• PVC clamp-on type water nozzles.
• ‘S’ (2 pass) Type PVC eliminator sheets.
• The correct size of the air washer section.
• The size of the supply air duct.
• Uniform air distribution system.
• Power saving of about 25% to 60% in existing humidification plants.