These days it seems that operating budgets are being constantly challenged, scrutinized and dissected almost every season. Many facility managers are being asked to justify their operating budgets on a bi-yearly or quarterly basis. As a top water treatment company in NJ, we are often constantly asked to figure out ways to help our customers reduce their operating costs. Managers are often under pressure to identify areas in their budgets that can be slashed; at some point the topic of cutting the water treatment budget comes up.
So can you cut down or eliminate some of your boiler water treatment chemicals and still expect good results? If using the correct amount of boiler chemicals protects the boiler, won’t feeding a little less boiler chemical still be ok? It can't be that bad, right?
Well, not exactly. When it comes to industrial water treatment chemistry, there is very little ambiguity. Every boiler chemical that is fed to a steam system is fed for an explicit reason. The following is a list of the major chemical components to a typical steam boiler treatment program, what each chemical is designed to do and what could happen if you under feed them.
Oxygen scavengers are chemicals that are fed to consume any remaining oxygen that did not get eliminated from mechanical deaeration of the feed water. Sufficient feed of these chemicals is essential in order to consume the oxygen in the feed water before it can cause oxygen pitting corrosion in the feed water and boiler systems. Sulfite is measured as a residual (or what has not been consumed by the oxygen removal process) in the boiler. In many systems, most of the sulfite fed is what is used to build the residual level that you can accurately test for. In other systems where the mechanical deaeration is less than desirable, a great portion of the chemical fed is used to eliminate the oxygen and only a small percentage is used to build the residual which is measured in the boiler.
Typically, for a well-run boiler system with good mechanical deaeration, the goal of oxygen scavenger feeding is to have at least 1 PPM (parts per million) residual per cycle of concentration in the boiler or at least 30 PPM, which ever number is greater. This calculation certifies (at least mathematically) that there is at least 1 PPM of sulfite residual at all times in the feed water. This ensures that your feed water system is protected and the transfer of iron to the boiler (as a byproduct of the corrosion process) is minimal.
So, reducing oxygen scavenger feed jeopardizes the protection of the feed water system. If you are running a polymer program, this transfer of iron to the boiler system will then INCREASE the polymer demand in the boiler!
Scale and Deposit Control Chemicals
The most widely used internal treatment chemistries that are used to control scale deposition in boilers. They are nitrites, phosphates and polymers. Inadequate feeding of internal treatment chemistry (polymer) can result in both iron and calcium deposition on the heat exchange surfaces. This scale will impede heat transfer and will increase your fuel costs. Scale is also very detrimental to the projected lifespan of the heat exchange equipment. Scale does not form uniformly and, as a result, stress caused by temperature extremes will accumulate between the insulated (from scale) portions and the clean portions. This process can quickly fatigue system metal and ultimately cause system failure.
Proper alkalinity is needed to create the optimal environment for both polymer and orthophosphate boiler programs to work properly. Alkalinity Booster is needed for the proper precipitation and dispersion of hardness ions. It reacts with the scale and deposit control chemical and calcium in the water to create a soft calcium precipitate sludge that will eventually be eliminated through boiler blowdown.
Inadequate pH (alkalinity) in the feed water will result in corrosion of the feed water system and ultimately transport the iron byproducts of corrosion to the boiler which increases the polymer demand.
Neutralizing amines are fed to increase the pH of the returning condensate to between 8.3 and 9.0. Without amine feed, the pH of condensate is normally driven downwards during steam production due to the formation of carbonic acid in the condensate due to the breakdown of alkalinity in the boiler water. Neutralizing amines counteract the acidity due to the formation of carbonic acid. Under feeding amines will result in increased corrosion rates, and ultimately the transfer of iron byproducts of corrosion back to the boiler which (you guessed it) increases polymer demand.
In general, if overfeeding boiler treatment chemicals causes issues with carryover, then underfeeding boiler treatment chemicals causes issues with scale and corrosion. Cutting back on water treatment chemistry is often pennywise and pound foolish. An appropriate water treatment program will benefit the performance and efficiency of any boiler system, but in a steam boiler system it is even more serious. Problems in a steam boiler system that are caused by underfeeding boiler chemicals can escalate very quickly, and if no corrective measures are taken, these issues can lead to long interruptions of service and expensive repairs.
Under feeding boiler chemicals in a steam system can eventually lead to boiler tube failure. In the case of a rupture under pressure, consequences could be catastrophic. For these reasons, always be sure to consult with your boiler system manufacturer and get the advice of a reputable water treatment company before making any changes.
The takeaway here should be obvious: When considering your boiler water treatment budget, saving pennies today could wind up costing big dollars down the road.
If you would like to know more about the common mistakes that facility operators make during heating season, please download our free eBook “10 HUGE Mistakes Facilities Make in Boiler Operation and How to Avoid Them!” You can find link at the bottom of this post.
Thanks for reading!
Greg Frazier is an expert in Industrial Water Treatment and is currently the Managing Partner of Clarity Water Technologies. He has over 18 years of Industrial Water Treatment experience and holds a degree in Chemical Engineering from the University of Tennessee.