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Hydrazine Hydrate
No oxygen is entering the boiler with the feed water when hydrazine is present in the water ( This will help to decrease oxygen on HP, LP boiler )
The objective is to maintain a hydrazine residual between 0.05-0.2 ppm depending on operating pressure and boiler designe. Actual consumption is determined under operating conditions. A normal dosage is approximately 1 ltr. per day, depending of system layout.
Hydrazine is a convenient reductant because the by-products are typically nitrogen gas and water. Thus, it is used as an ANTIOXIDANT, an oxygen scavenger, and a corrosion inhibitor in water boilers and heating systems.
Hydrazine is mainly used as a foaming agent in preparing polymer foams.
No oxygen is entering the boiler with the feed water when hydrazine is present in the water.
Hydrazine is used as an oxygen scavenger for high pressure boilers in power plants and other industries to reduce corrosion of metal pipes and fittings. The test for hydrazine can be controlled by http://rxmarine.com/hydrazine-test-kit in which several solutions have been formulated into a single, stable reagent. The method is both sensitive and easy to perform. It is used mostly for the determination of small amounts of hydrazine in boiler feedwater. There are no common interferences.
The establishment of protective metal oxide layers through the use of reducing agents (such as hydrazine, hydroquinone, and other oxygen scavengers) is known as metal passivation or metal conditioning. Although "metal passivation" refers to the direct reaction of the compound with the metal oxide and "metal conditioning" more broadly refers to the promotion of a protective surface, the two terms are frequently used interchangeably.
The reaction of hydrazine and hydroquinone, which leads to the passivation of iron-based metals, proceeds according to the following reactions:
| N2H4 | + | 6Fe2O3 | ® | 4Fe3O4 | + | 2H2O | + | N2 |
| hydrazine | hematite | magnetite | water | nitrogen |
| C6H4(OH)2 | + | 3Fe2O3 | ® | 2Fe3O4 | + | C6H4O2 | + | H2O |
| hydroquinone | hematite | magnetite | benzoquinone | water |
Similar reactions occur with copper-based metals:
| N2H4 | + | 4CuO | ® | 2Cu2O | + | 2H2O | + | N2 |
| hydrazine | cupric oxide | cuprous oxide | water | nitrogen |
| C6H6O2 | + | 2CuO | ® | Cu2O | + | C6H4O2 | + | H2O |
| hydroquinone | cupric oxide | cuprous oxide | benzoquinone | water |
Magnetite and cuprous oxide form protective films on the metal surface. Because these oxides are formed under reducing conditions, removal of the dissolved oxygen from boiler feedwater and condensate promotes their formation. The effective application of oxygen scavengers indirectly leads to passivated metal surfaces and less metal oxide transport to the boiler whether or not the scavenger reacts directly with the metal surface.
The establishment of protective metal oxide lay-ers through the use of reducing agents (such as hydrazine, hydroquinone, and other oxygen scavengers) is known as metal passivation or metal conditioning. Although "metal passivation" refers to the direct reaction of the compound with the metal oxide and "metal conditioning" more broadly refers to the promotion of a protective surface, the two terms are frequently used interchangeably.
The reaction of hydrazine and hydroquinone, which leads to the passivation of iron-based metals, proceeds according to the following reactions:
| N2H4 | + | 6Fe2O3 | ® | 4Fe3O4 | + | 2H2O | + | N2 |
| hydrazine | hematite | magnetite | water | nitrogen |
| C6H4(OH)2 | + | 3Fe2O3 | ® | 2Fe3O4 | + | C6H4O2 | + | H2O |
| hydroquinone | hematite | magnetite | benzoquinone | water |
Similar reactions occur with copper-based metals:
| N2H4 | + | 4CuO | ® | 2Cu2O | + | 2H2O | + | N2 |
| hydrazine | cupric oxide | cuprous oxide | water | nitrogen |
| C6H6O2 | + | 2CuO | ® | Cu2O | + | C6H4O2 | + | H2O |
| hydroquinone | cupric oxide | cuprous oxide | benzoquinone | water |
Magnetite and cuprous oxide form protective films on the metal surface. Because these oxides are formed under reducing conditions, removal of the dissolved oxygen from boiler feedwater and condensate promotes their formation. The effective application of oxygen scavengers indirectly leads to passivated metal surfaces and less metal oxide transport to the boiler whether or not the scavenger reacts directly with the metal surface.
Why control balance of Hydrazine must required ?
Control of Hydarazine level in Boiler water is very important. As proper level maintenance protect metal machinery parts from corrosion, However, precautions must be taken to prevent excess dose of hydrazine chemical as excess hydrazine will begin to decompose at temperature above 200oC to form Ammonia.
Hydrazine is one of popular an alternative Oxygen Scavenger. It is very important to protect boiler components from feed boiler water corrosion.
Test Procedure ::: rxmarine.com/hydrazine-test-kit
Physical properties
| Molecular formula: | H2NNH2 |
| CAS No.: | 000302012 |
| Molecular weight: | 32.05 |
| Description: | colorless, oily liquid, fuming in air. |
| Odor: | penetrating odor resembling that of ammonia |
| Density: | 1.0036 (25/4°C) |
| Boiling point: | 113.5°C (at 760 mm Hg) |
| Freezing point: | 1.4 - 1.5°C |
| Explosive limits: | 4.7 - 100% by volume in air |
| Flash point: | 38 - 52°C (open cup) |
| Saturation concentration: | 18900 ppm |
| Conversion factors: | 1 ppm = 1.31 mg/m3 |
| (at 760 mm and 25°C) | 1 mg/m3 = 0.76 ppm |
| Solubility: | soluble in water, ethanol, and isobutanol; insoluble in chloroform and ether |
| Vapor density: | 1.04 (air = 1) |
| Vapor pressure: |
14.4 mm Hg at 25°C |
Hydrazine is used as an oxygen scavenger for high pressure boilers in power plants and other industries to reduce corrosion of metal pipes and fittings. Hydrazine Test Method, in which several solutions have been formulated as a Hydrazine Reagent. The method is both sensitive and easy to perform. It is used mostly for the determination of small amounts of hydrazine in boiler feedwater.