Boiler Water Oxygen Scavengers - Sulphite, Tannin, DEHA, Carbohydrazide

Boiler Water Oxygen Scavengers - Why should you worry about oxygen in boiler water? Primarily because oxygen is a significant factor in the corrosion of metals. Accordingly, if you can remove the oxygen from water you can reduce the negative effects of corrosion. Boiler water oxygen scavengers do just that; they are products that can be added to the boiler water that help to remove oxygen and so reduce the problems associated with corrosion.

Oxygen Scavengers

There are several types of oxygen scavenger: organic and inorganic, the difference being that inorganic products add dissolved solids to the water. This means that you have to increase the amount of 'blowdown' given to the boiler to maintain conditions free from boiler water carryover. Also, inorganic oxygen scavengers tend to be temperature dependent and so the lower the boiler feed water temperature the more chemical you need to add. An example of an inorganic oxygen scavenger is sulphite, whereas examples of organic oxygen scavengers are tannin, DEHA, and carbohydrazide.

Reducing Oxygen

Advanced Corrosion Control

One method used to reduce the amount of oxygen in boiler feed water is to maintain as high a temperature as possible. This is because increasing the water temperature can drive off the oxygen in gaseous form. It is therefore essential to ensure good feed tank design, and that as much condensate as possible is returned to the system. The use of condensate is preferable for heating the feed tank rather than a steam sparge or external heat source, because it is a recycled heat source and so helps to conserve energy and reduce operating costs.

Sulphite

Advantages to the use of sulphite are that the higher the feed water temperature the less sulphite is required, its low cost and it is colourless as a product. One disadvantage is that sulphite adds to the 'dissolved solids' and so leads to more system 'blowdowns'.

Tannin, DEHA & Carbohydrazide

Tannins, DEHA and carbohydrazide are not temperature dependent and do not add to the 'dissolved solids' and hence blowdown is reduced relative to a sulphite treated boiler, however, these products are slightly more expensive than sulphite.

Product Selection

It is important to calculate the dosage rate for all types of product and to examine the overall system design before choosing the most suitable scavenger.

Accepta have a number of highly effective, technically advanced products that act to absorb oxygen from boiler water and so help prevent corrosion:

Tannin Based Scavenger - Accepta 2012 is not dependant on the feed-water temperature and being organic it does not add to the boiler water conductivity so reducing the need for blowdown (compared with sulphite) ... tannin based scavenger >>

DEHA - Accepta 2061 provides outstanding protection from oxygen corrosion along with excellent feed-water and boiler system passivation. It can be used as a replacement for hydrazine in any boiler up to 125 bar without the associated safety hazards and handling precautions. Accepta 2061 is volatile and alkaline, contributing no dissolved solids or ammonia to the boiler system ... DEHA >>

Carbohydrazide - Accepta 2065 is an organic corrosion inhibitor used for scavenging oxygen and passivating metal surfaces. It can be used as a direct replacement for hydrazine in any boiler without the associated safety hazards and handling precautions. It can be used in boilers of any pressure, up to and including supercritical (220 bar g), and can be fed into feed-waters used for spray attemperation ... carbohydrazide >>

Catalysed Sodium Sulphite - Accepta 2972 is an efficient catalysed sodium sulphite product used to absorb oxygen in steam boiler systems. Dose ideally to feed tank to allow time for the oxygen to be absorbed before entering the steam boiler ... catalysed sodium sulphite >>

Multifunctional Sulphite - Accepta 2879 is an excellent multifunctional product developed for boilers and boiler water systems. Accepta 2879 contains catalysed bisulphite, for rapid and complete oxygen scavenging, phosphates for the control of precipitation, and powerful antiscalants and dispersants to mobilise hardness or iron oxide sludges and prevent thereby prevent scale ... multifunctional sulphite >>

Powdered Sulphite (Inorganic) - Accepta 2082 is an excellent, traditional catalysed, non-volatile, inorganic boiler water oxygen scavenger in powdered form. Accepta 2082 was developed for use in boiler systems operating at pressures of up to 60 bar g ... powdered sulphite (inorganic) >>

Novel Oxygen Scavenger with Polymer - Accepta 2084 is an advanced, non-volatile, organic corrosion inhibitor with additional polymer, developed for scavenging oxygen and passivating metal surfaces in boiler systems. Accepta 2084 is based on erythorbic acid ... novel oxygen scavenger with polymer >>

Multifunctional Treatment - Accepta 2889 is a very versatile, combined tannin and carbonate based multi-functional water treatment product developed for use in boilers and closed circuit heating systems ... multifunctional treatment >>

Sulphite with Alkalinity Builder - Accepta 2897 is a superior quality sulphite based water treatment product with added caustic, developed for use in steam boiler applications ... sulphite with alkalinity builder >>

Carbohydrazide - Accepta 2104 is an innovative carbohydrazide, condensate line treatment developed for use as a corrosion inhibitor in steam and condensate systems. Accepta 2104 may be used at temperatures up to 500°F [260°C]. Accepta 2104 contains high, medium and low volatility amines which provide effective neutralisation of acidic gases, such as CO2, throughout a condensate system ... carbohydrazide >>

Tannin Based - Accepta 2319 is a superior, blended liquid water treatment product based on organic tannins, polymer sludge, conditioners and alkali. Developed for steam boilers and LPHW systems, Accepta 2319 can be used with softened or moderately hard make-up, and in many instances provides a complete balanced treatment by itself ... tannin based >>

Tannin Based - Accepta 2320 is an excellent, blended liquid treatment for the control of scale and corrosion in steam boiler systems. Accepta 2320 is based on organic tannin, polymer sludge conditioners and alkali ... tannin based >>

Tannin Based - Accepta 2812 is not dependant on the feed-water temperature and being organic it does not add to the boiler water conductivity so reducing the need for blowdown ... tannin based scavenger >>

Additional Information & Technical Support

For further information, technical support and advice please call Accepta on +44 (0) 161 877 2334 or e-mail info@accepta.com. For additional products, specifications, product data and MSDS's please review our products pages.