Boiler Water Treatment Chemicals

Boiler Treatment Chemicals

The primary objectives in boiler design, operation and effective treatment include: efficiency in heat transfer, minimisation of energy usage, production of pure steam and safe, reliable operation.

The problems encountered in steam-raising plant can be severe if scale formation and corrosion are allowed to occur. Problems can range from loss of efficiency and reduction of plant life to, at worst, catastrophic failure. It is also necessary to prevent boiler water carryover, where boiler water (including its dissolved solids) is carried into the steam, sludge deposition and foaming.

Both external and internal treatment of the boiler water is used for optimal operation. An effective internal boiler treatment programme involves the addition of chemicals to the feed water, boiler water and steam in order to confer desirable attributes, or to react with traces of undesirable constituents which can remain after external treatment. Typically, oxygen scavengers, dispersants and alkalinity builders are standard. Other products including condensate line corrosion inhibitors and antifoams may also be used.

Oxygen Scavengers

A major cause of corrosion in boilers is dissolved oxygen, particularly in conjunction with low pH (low alkalinity) although excessive alkalinity can also be a factor. Chemical oxygen scavengers are used to eliminate oxygen from the feed water. The main types of oxygen scavenger are shown below:

Product code	Composition	Comments
ZI669	Sulphite based.	FDA approved, catalysed sodium metabisulphite.
ZI177	Sulphite and DEHA based.	Dual action corrosion inhibitor for steam raising plant and hot water systems. Generally used in smaller systems.
ZI173	Tannin Based.	FDA approved. Concentrated formulation. Useful for boilers with low feedwater temperature.
ZI387	Tannin Based.	FDA approved. Useful for boilers with low feedwater temperature.
ZI166	Sodium Erythorbate.	For steam raising plant operating up to 40bar. Can be used where the steam comes into contact with food or food products.
ZI449	Sodium erythorbate and neutralising amine based formulation.	For steam raising plant operating up to 40bar. Can be used where the steam comes into contact with food or food products (other than milk and providing the neutralising amine is less than 15ppm in the condensate).
ZI176	DEHA based formulation.	Very concentrated DEHA based formulation.
ZI169	DEHA based formulation + catalyst	Very concentrated DEHA based formulation + catalyst.
ZI175	DEHA based formulation.	For steam raising plant and hot water systems including medium pressure hot water systems.
ZI681	Carbohydrazide based formulation	Suitable for use in boilers of any pressure up to and including supercritical (220 bar g)
ZI899	Concentrated Carbohydrazide based formulation	Concentrated formulation. Suitable for use in boilers of any pressure up to and including supercritical (220 bar g)

Dispersants

Scale results from the formation of insoluble calcium and magnesium salts and is seen as a rock like coating on the inside of boiler tubes. A conditioner is required which will react with any residual hardness present in the incoming feed water, and prevent precipitation of scale onto the boiler surface. Phosphate, polymers and chelant treatments are typically used. Sludge conditioners tend to be organic polymers and help to prevent the adherence of suspended solids onto heat transfer surfaces. The polymers combine with precipitates and the resultant electrical charge on the particle surface enables the particles to be dispersed so that they may be removed by blow-down.

Product code	Composition	Comments
ZI34	Polymer and phosphate based formulation	For use as a scale and sludge conditioner for steam boilers preventing scales adhering to the metal surfaces. Use with softened or low hardness waters, FDA approved. Concentrated formulation.
ZI1237	Polymer, phosphate and caustic based formulation	For use as a scale and sludge conditioner for steam boilers preventing scales adhering to the metal surfaces. Use with softened or low hardness waters, FDA approved. Concentrated formulation. Increases alkalinity.
ZI37	A blend of polymers and sequestrants.	Useful for cleaning scale and sludge from boilers whilst they are on-line. FDA approved.
ZI666	Polymer and phosphate based formulation.	A boiler feedwater treatment for the control of scale. Suitable for low hardness, softened and de-alkalised feedwater.
ZI802	Polymer and phosphate based formulation.	A powdered dispersant and sludge conditioner for steam raising plant. Includes an antifoam.
ZI450	Polymer and phosphate based formulation.	A pH regulator for high pressure steam generation plant. Contains only components approved by the FDA for the treatment of boilers where the steam contacts food.
ZI451	Phosphate and caustic based formulation.	A pH regulator for high pressure steam generation plant. Contains only components approved by the FDA for the treatment of boilers where the steam contacts food.
ZI917	Phosphate and caustic based formulation.	A pH regulator for high pressure steam generation plant. Contains only components approved by the FDA for the treatment of boilers where the steam contacts food.

Alkalinity Builders

Product code	Composition	Comments
ZI24	An aqueous solution of sodium hydroxide.	A pH adjuster for steam boilers where there is insufficient alkalinity in the feed water. Complies with FDA regulations for steam that comes into contact with food.
ZI792	An aqueous solution of sodium hydroxide + polymer.	A pH adjuster for steam boilers where there is insufficient alkalinity in the feed water. Also contains a polymer dispersant which disperses residual hardness. Complies with FDA regulations.
ZI23	An aqueous solution of sodium hydroxide.	Concentrated pH adjuster for steam boilers where there is insufficient alkalinity in the feed water. Complies with FDA regulations for steam that comes into contact with food.
ZI518	An aqueous solution of sodium hydroxide.	Very concentrated pH adjuster for steam boilers where there is insufficient alkalinity in the feed water. Complies with FDA regulations for steam that comes into contact with food.
ZI965	An aqueous solution of sodium and potassium hydroxide.	Very concentrated formulation. pH adjuster for steam boilers where there is insufficient alkalinity in the feed water.

Return Line Treatments

Corrosion can also occur in condensate return lines. Corrosion can be caused by oxygen in the steam or carbon dioxide which leads to the production of carbonic acid. Oxygen should ideally have been dealt with by the treatment of the feed water but any remaining can be removed using steam volatile oxygen scavengers. Carbon dioxide corrosion can be controlled by pre-treatment techniques or by the addition of steam volatile neutralising and filming amines. Filming amines are generally dosed into the steam lines and form a protective film on the surface of the condensate lines. Neutralising amines enter the condensate lines with the steam and neutralise the carbonic acid thereby raising the pH.

Product code	Composition	Comments
ZI214	Cyclohexylamine based formulation.	Condensate line corrosion inhibitor for steam raising plant.
ZI216	Filming amines and neutralising amines.	A combination of filming amines and neutralising amines for the prevention of condensate pipework corrosion.
ZI218	Filming amine.	A filming amine – prevents corrosion of condensate pipework. Should be injected directly into the steam header.
ZI219	Cyclohexylamine and morpholine based formulation.	Condensate line corrosion inhibitor for steam raising plant.
ZI222	Combination of 2 neutralising amines.	Condensate line corrosion inhibitor for steam raising plant.
ZI223	Mixed amines + DEHA	Condensate line corrosion inhibitor for steam raising plant. Extends the life of condensate pipework by retarding the rate of ‘grooving’ by acidic condensate. Also protects return lines by scavenging dissolved oxygen.
ZI224	Combination of 3 neutralising amines.	Condensate line corrosion inhibitor for steam raising plant.
ZI215	Mixed amines + DEHA.	Condensate line corrosion inhibitor for steam raising plant. Extends the life of condensate pipework by retarding the rate of ‘grooving’ by acidic condensate. Also protects return lines by scavenging dissolved oxygen.
ZI225	Cyclohexylamine and morpholine based formulation.	More concentrated formulation of BV219 but with differing amine ratios.
ZI452	Combination of 3 neutralising amines.	More concentrated formulation of BV224 but with differing amine ratios.
ZI467	Non-amine based.	A low toxicity condensate line corrosion inhibitor. FDA approved for use in steam raising plant where the steam contacts food. Maximum approved dose rate 20ppm. Must be dosed into steam header.

Multipurpose Boiler Treatments

Sulphite based

All the below sulphite based multi-purpose boiler products comply with the FDA regulations for steam that comes into contact with food. The below product formulations differ in their composition in particular in their sulphite and caustic levels. If further advice on product selection is required please contact the Technical Team at Zagosa Industrial.

Product code	Composition	Comments
ZI399	Catalysed Sulphite, phosphate, polymer, low caustic.	A multipurpose sulphite based product for smaller steam boilers. . This product complies with FDA regulations for steam that comes into contact with food.
ZI150	Catalysed Sulphite, phosphate, polymer, high caustic.	A multipurpose sulphite based product for smaller steam boilers. . This product complies with FDA regulations for steam that comes into contact with food.
ZI151	Catalysed Sulphite, polymer, high caustic.	A multipurpose sulphite based product for small steam boilers, low and medium hot water systems or steam generators. . This product complies with FDA regulations for steam that comes into contact with food.
ZI805	Catalysed Sulphite, phosphate, polymer, high caustic.	A multipurpose concentrated sulphite based product for steam raising plant. . This product complies with FDA regulations for steam that comes into contact with food.
ZI1001	Catalysed Sulphite, phosphate, polymer, high caustic.	A multipurpose concentrated sulphite based product for steam raising plant. . This product complies with FDA regulations for steam that comes into contact with food.
ZI149	High catalysed Sulphite, phosphate, polymer, low caustic.	A multipurpose concentrated sulphite based product for steam raising plant. . This product complies with FDA regulations for steam that comes into contact with food.

Polyamine Based

Low solids multi-purpose ‘one drum’ products.

Product code	Composition	Comments
ZI1112	A blend of polyamines, neutralising amines and polymers.	An organic based product which prevents corrosion in boilers fed on softened water, by forming a protective film on metal surfaces. The volatility of the components ensures protection of steam and condensate lines from a single dosing position, as well as the feed and boiler system.
ZI1045	A blend of polyamines and neutralising amines.	An organic based product which prevents corrosion in boilers fed on demineralised water, by forming a protective film on metal surfaces. The volatility of the components ensures protection of steam and condensate lines from a single dosing position, as well as the feed and boiler system.

Tannin Based

Product code	Composition	Comments
ZI144	Tannin and sodium hydroxide based formulation.	A multipurpose product containing an oxygen scavenger with added alkalinity for steam boilers and LPHW. . This product complies with FDA regulations for steam that comes into contact with food.
ZI697	Tannin and polymeric dispersant based formulation.	A multipurpose product containing an oxygen scavenger with dispersants. Ideal for the protection of cold feed systems and for the protection of intermittently operated boiler plant. This product complies with FDA regulations for steam that comes into contact with food.
ZI970	Tannin, sodium hydroxide and polymer based formulation.	A multipurpose product containing an oxygen scavenger with dispersants and caustic alkalinity. Suitable for cold feed systems where dissolved oxygen levels are high. . This product complies with FDA regulations for steam that comes into contact with food.
ZI1434	Tannin, sodium hydroxide and polymer based formulation.	A multipurpose product for smaller boilers containing an oxygen scavenger with dispersants and caustic alkalinity. Suitable for cold feed systems where dissolved oxygen levels are high. . This product complies with FDA regulations for steam that comes into contact with food.

Specialist Products

Product code	Composition	Comments
ZI1	Boiler anti-foam. Polyalkyl glycol ether based formulation.	An antifoam suitable for steam boilers to prevent foaming and carryover of the boiler water into the steam. Acts as the water steam interface to control foam generation. This product complies with FDA regulations for steam that comes into contact with food.
ZI243	Alkaline ‘boil-out’ chemical. Sodium hydroxide, low foaming surfactant and polymeric dispersant based formulation.	A combination of strong alkalis and surfactants for removing grease and manufacturing debris for new steam boilers before commissioning and being placed into service.
ZI74	Fuel treatment. Magnesium soap in petroleum distillate based formulation.	A fuel additive to improve the combustion of heavy fuel oil and to keep heat transfer surfaces clean.
ZI83	Resin cleaner Phosphonates and organic acid.	A resin cleaner for base exchange softening plant.
ZI85	Crushed dolomitic limestone for pH correction	Effective acid neutralising product, neutralises acid effluent.
ZI501	Salt granules	For regeneration of base exchange softener resins.
Acid scaling
ZI78	28% Hydrochloric acid.	For acid descaling.
ZI1535	Hydrochloric acid 32% + corrosion inhibitor	A highly active acid cleaner and descaler. Also includes a corrosion inhibitor to protect bare metal surfaces particularly carbon steel. Removes both calcium and iron deposits.
ZI13	Aliphatic amine based corrosion inhibitor	Confers corrosion inhibition during descaling with Hydrochloric acid
ZI42	Sulphamic acid crystals	Mild acid descaler. Crystals. Dissolve in water to produce a 5 – 10% solution.
ZI43	Sulphamic acid crystals + amine based corrosion inhibitor.	A highly active combination of acid cleaner and descaler with corrosion inhibitor to protect carbon steel, copper and brass against acid attacks. It can be used on a wide variety of metals including stainless steel. Dissolve crystals in water to produce a 5 – 10% solution then add inhibitor as instructed on product data sheet.
ZI231	Sulphamic acid solution	Ready to use Sulphamic acid descaler.
ZI8	Mineral oil based antifoam	Gives foam control during descaling operations.

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