Oxygen scavenger presentation

Oxygen Scavenger Use's &

Safety Precaution

Prepared By : -

Umar Farooq Chemist “A” Chemical Section

[email protected]

[email protected]

SEC Shuaibah Jeddah

Saudi Arabia 1

mailto:[email protected]





Exposure • In order for a chemical to produce a biological effect, it must first reach a

target individual (exposure pathway).

• Then the chemical must reach a target site within the body

(toxicokinetics).

• Toxicity is a function of the effective dose (how much) of a foreign

chemical (xenobiotic) at its target site, integrated over time (how long).

• Individual factors such as body weight will influence the dose at the

target site

X =

2

Umar Farooq Chemist “ A”

SEC Shoaiba Jeddah

http://www.stewartwarner.com/

Route of Exposure

Route of Exposure

• The route (site) of exposure is an important determinant of the ultimate dose—different routes may result in different rates of absorption.

Dermal (skin)

Inhalation (lung)

Oral ingestion (Gastrointestinal)

Injection

• The route of exposure may be important if there are tissue-specific toxic responses.

• Toxic effects may be local or systemic

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SEC Shoaiba Jeddah

Time of Exposure

Time of Exposure

• How long an the Person & organism is exposed to a chemical is important

Duration and frequency contribute to dose. Both may alter toxic effects.

Acute Exposure = usually entails a single exposure

Chronic Exposures = multiple exposures over time (frequency)

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SEC Shoaiba Jeddah

Father of Modern Toxicology Paracelsus—1564

“All things are poisonous, only the dose makes it non-poisonous.”

Dose alone determines toxicity

All chemicals—synthetic or natural—have the capacity

to be toxic

Dose THE KEY CONCEPT in Toxicology

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The emerging field of

“Pharmacogenomics” or

“Toxicogenomics” offers

the potential to identify and protect

subsets of people predisposed to

toxicity from chemicals or drugs

Typical Population

Identify People with “normal” responses

More

Sensitive

Less

Sensitive

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Oxygen Scavenger An oxygen scavenger is a chemical which

remove dissolve O2 in H2O by a reduction reaction and

there by inhibits to corrosion cause by the O2. we

discussed here following two type of oxygen scavenger

1) Sodium Sulphite Na2SO3

2) Hydrazine N2H4

Sodium Sulfite

In practice I ppm of oxygen required 8ppm of

Na2SO3 . The major disadvantage in it are is that 8ppm .

Na2SO3 contribute 9ppm of Na2SO3 into total dissolved

solid in the boiler consequently increasing blow down

. Sodium sulphite recommended for boiler operation at

pressure below 600 pisg. Umar Farooq Chemist “ A”

SEC Shoaiba Jeddah 7

Sodium Sulphite

The main disadvantage of

use sodium sulphite is decomposition

Na2SO3 + H2O 2NaOH +SO2

Na2SO3 + H2O 3NaSO4 + 2NaOH +H2S

The main problem associated

with sulphite break down is the formation of

corrosive gases So2 and H2S which can cause

corrosion in after boiler section



Hydrazine

Use in power plant

In the treatment of feed

water system to protect Boiler and

pre boiler equipment’s from

oxygen attack’s

If left untreated, boiler

water derived oxygen will corrode

metallic boiler components leading

to increased maintenance costs

and reduced boiler efficiency.



Hydrazine Treatment Hydrazine ( N2H4 ) can economically remove

small amount of dissolved oxygen . In addition it acts to

produce nitrogen and water thereby leaving the TDS

level of water un effected.

N2H4 + O2 N2 + 2H2O

Theoretically 1ppm of hydrazine is required to

react with 1ppm dissolved “ O2 “ but actually 1.5 to 2.0

ppm of N2H4 are required per 1ppm “ O2”

Hydrazine also react with Fe2O3 in the boiler

water to form a passive magnitude film on the boiler

surface preventing form the corrosion.

N2H4 + 6Fe2O3 4Fe3O4 + N2 + 2H2O



Hydrazine Decomposition

Thermal decomposition of hydrazine

takes place above ( 270 C° ) ( 518 F ° ) Through

it influence by reaction time .

N2H4 NH3 + N2

270 c°

Since NH3 is produced by

decomposing of hydrazine , Normally copper

material is used in the steam and condensate

piping . The injection of excess hydrazine should

be avoided. Umar Farooq Chemist “ A”


Other use of Hydrazine

Rocket Fuel: Hydrazine was first used as a Rocket Fuel during World War II for

the Messerschmitt Me 163B (the first rocket-powered fighter plane).

Hydrazine is also used as a low-power monopropellant for the maneuvering thrusters

of spacecraft and was used to power the Space Shuttle's auxiliary power units

(APUs)

In all hydrazine monopropellant engines, the hydrazine is passed by a catalyst

such as iridium metal supported by high-surface-area alumina (aluminum oxide)

or carbon nanofibers or more recently molybdenum nitride on alumina, which causes

it to decompose into ammonia, nitrogen gas, and hydrogen gas according to the

following reactions

3 N2H4 → 4 NH3 + N2

N2H4 → N2 + 2 H2

4 NH3 + N2H4 → 3 N2 + 8 H2

Reactions 1 and 2 are extremely exothermic (the catalyst chamber can reach 800 °C

in a matter of milliseconds) and they produce large volumes of hot gas from a small

volume of liquid



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Eye Protection

Safety Glasses /

Goggles

Face

Shield

Respiratory System Protection

Dust mask

Respirator with Charcoal

Filter

General Purpose

Respirator SCBA

Skin Protection

Apron

Closed Shoes / Boots

Chemical Gloves

Impermeable Suite


SEC Shoaiba Jeddah

Hydrazine Safety & Hazed Properties :

Hydrazine is a color less

flammable liquid with an ammonia-like order

.Hydrazine is highly toxic and dangerously

unstable unless handle in solution

Safety & Hazard

EU classification

Flammable liquid and vapor

Fatal in contact with skin

Fatal if inhaled vapor

Toxic if swallowed

Causes severe skin burns and eye damage

May cause an allergic skin reaction

Suspected of causing genetic defects

Suspected of causing cancer

Causes damage to liver and central nervous

system

Causes damage the lungs, the kidneys and

the central nervous system through

prolonged or repeated exposure Very toxic to aquatic life with long lasting

effects



Materials Causing Immediate and

Serious Toxic Effects

Characteristics

May cause immediate

death or serious injury if

inhaled, swallowed, or

absorbed through the skin

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Hydrazine Replacement

Carbohydrazide based boiler water

oxygen scavenger that can be used as

a direct replacement for hydrazine.

High performance carbohydrazide

based oxygen scavenger giving

outstanding protection from oxygen

corrosion, plus feed water and boiler

system passivation.

Improved safety - a direct

replacement for hydrazine.

Used in boilers of any pressure up to

220 barg.





Environment

Oxygen scavenger presentation