Is it possible to used liquid NH4OH instead of Organic Amine to maintain the ph level of water in boilers?

Is it possible to used liquid NH4OH instead of Organic Amine to maintain the ph level of water in boilers? The pH adjustable is the main chemical used to maintain the water pH between 8.5-9.5 as per the boiler specification requirements, norms and standard. For that purpose Organic amines injected into Heat Recovery Steam Generation (HRSG), to adjust the pH. Due to The high cost of chemical based Amin, then alternative such as NH4OH proposed.

There are many challenges such as reaction of ammonia with chloride, which may lead, sever corrosion of the boiler tubes specially in Amal boilers because of the boiler feed water containing 3000 ppm chloride where in plant it can't exceed more than 6 ppm.

Will you please guide us that which standards or possible methods should we followed to proceed further. 

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• Cooling Boiler & Wastewater
• Alkaline
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• Industrial Water Managment
• Utility Boiler and Cooling Water Treatment
• water treatment

3 Answers

1. The chloride level is too high coming from the boiler feed water against the spec < 6 ppm. Actually chloride spec 6 ppm is referred to which boiler pressure. The source of  boiler water is not explained in the above write up. Before changing to other treatment, you need to find the reason of high chloride in the boiler feed water.  Besides that, the pH that you are operating is too big band and best to control at narrow band i.e. 8.8 to 9.2 as an example. 

2. You don't say what the boiler pressures are.  I would be very worried about the boiler corrosion due to the high chloride levels.  Some ammonium hydroxide will break down and ammonia will evaporate and although it will neutralise some of the carbonic acid it will corrode any copper or brass it comes across.

   A level of 3000 ppm is 0.3% chloride.  This contributes to the total dissolved solids and you will exceed the boiler total dissolved solids very quickly.  Once they are exceeded the boiler will start foaming and carry with it boiler water and this itself causes damage to the equipment and the steam and condensate lines as well as reducing heat transfer because it is wet steam not dry.

   High levels of chloride will attack and damage the level controls in place to not only control the water levels in the boiler but could prevent the burner from cutting out in the event of the extra low level and this would result in extreme damage to the boiler including the possibility of a boiler explosion.

3. I have not come across the situation that boiler feed water containing 3000 ppm chloride. Please verify the values. Ammonia alone is used in most of the utility boilers for maintaining the pH. However OEM's recommendation has to be followed since the recommendation is based on the metallurgy, pH variation in condensation /vaporization zone etc.