Sources of water
Boiler and cooling tower scaling is very expensive to control. The easiest control is no or minimal chemical control. The fewer chemicals you have to put into your boiler or cooling tower, the longer it will operate problem free and the the lower your costs will be. Using a pure water feed with minimal chemical additions, you will:
Minimize chemical costs
Greatly decrease the frequency of blowdown in your feed and bleed. For example: If your capacity is 1000 gallons and the feedwater is at 200 ppm, evaporating 50% and refilling, then blow down at 1200 ppm, you get about 10 cycles (each cycle adds 100 ppm). If you put 5 ppm in, you get 478 cycles (each cycle adds 2.5 ppm).
If you purge 1000 gallons, per blowdown, that is a savings of 46,800 gallons over one 1200 PPM cycle !
• Reduce maintenance and downtime
• Extend boiler life
Boiler feed water costs are associated with the following parameters
• Oxygen and carbon dioxide concentration
• Dissolved solids
• Suspended solids
• Concentration organics
Remco systems can be utilized to minimize the need for other types of treatment and maintenance associated with these parameters. With the proper pretreatment, water discharge can be reduced to a small fraction of the present volume that will lower treatment costs.
Usual treatments include:
• Water softening for hardness. Calcium and Magnesium (hardness ions) are removed by the softening process. Ca and Mg are exchanged for sodium ions on an ion exchange resin. Hardness in water causes scale. Scale is usually Calcium and/or Magnesium carbonate that precipitates out as the ions are concentrated in the boiler. Chemicals can be added to control scale but they can be reduced to a very small quantity if a softener is used.
• Pervaporation, a membrane process or deaerator can be used to remove Oxygen and CO2 down to very low levels for high pressure boilers. Only small amounts of chemical oxygen scavengers are required after oxygen removal.
• Silicates cause another type of scaling and can be removed with ion exchange or a membrane process. Membrane systems are preferred where dissolved ion concentrations are high because of operating cost considerations. High silicate levels are difficult and may require co-precipitation with other ions or high temperature caustic regeneration of ion exchange system.
• Dissolved solids can be removed by ion exchange or Reverse Osmosis membrane processes. The results are similar with ion exchange able to remove practically all the ions and RO able to get very close with lower operating and maintenance costs. With high TDS concentrating, a combination of the two can be very cost effective. The advantage of removing dissolved solids is that you can greatly increase the time between blow downs as the makeup water is almost void of solids. It takes much longer to get to the concentration when the boiler should be blown.
• Suspended solids are removed by filtration. Normally, you would want a backwashing filter followed by a fine cartridge filter for the best results. The backwashing filter can take high solids loading before flows are reduced and is self cleaning. The polishing filter makes sure any residual material does not get through.
• Concentration of organics are less of a problem in a properly designed feedwater system because much less chemistry is required to maintain the boiler. It is much easier to balance the system, and in some systems, no oxygen scavenger is required.
Remember, a good water analysis is you best friend. We will ask you for a water analysis. Print out the attached form if you don't know what you need to measure.
Boiler Water Quality Links:
Boiler Water Treatment: Lessons Learned (US Army)
Minimize Boiler Blow down
Improving Steam System Performance: A Sourcebook for Industry
Steam Handbook: Chapter 2, Water Treatment
As it is seen from the above diagram only 3.0% of earths water is fresh water. Out of this only 30.1 % & 0.3 % is useable.
No water, irrespective of the original source, should be assumed to be completely free of contamination & pollution. These contaminations may be natural or man made. The common contaminations, impurities & pollution in water are odor, tastes, colour, turbidity, suspended solids, organic and inorganic pollutants like pesticides, insecticides, herbicides, VOCs, dissolved gases, dissolved solids, heavy metals, domestic, chemical & industrial waste, bacteria, virus, Water Treatment is a Physical & Chemical process for making water suitable for human consumption and other processes.
As contaminations and pollutions of water are different, treatment required depend upon nature of contamination. Most of the times combinations of treatment technologies are used to treat water.
Water purification is the process where microbiological contamination is controlled. Again various technologies are used for water purification.
where water & water treatment is required :
Human consumption :
Drinking, cooking, bathing, washing, cleaning etc.
Process Industries :
Package drinking water plants, Food, hotel, medicine, pharmaceutical, laundry, cooling towers, boilers, swimming pool, molding machines, different manufacturing units, aqua cultures, construction, etc.
Different Technologies used as Water Treatment & Purifications :
Sedimentation, Coagulation, filtration, activated carbon, chemical disinfection, conditioning, softening, ion exchange, ultra violet, reverse osmosis, ozonation,
List of Contaminants & their MCL :
• Disinfection Byproducts
• Inorganic Chemicals
• Organic Chemicals