The document discusses ash corrosion that can occur in industrial instruments from mazut oils. It defines ash corrosion and describes the corrosion mechanism. Some key factors that influence ash corrosion are the concentration of molten salts or fuel impurities, temperature, and chemical composition of alloys. The corrosion is caused by deposits from combustion of fuels containing impurities like sulfur and vanadium. Solutions to prevent ash corrosion include proper material selection, temperature control, cleaning surfaces, and adding additives to fuels.

1. Ash Corrosion that Comes from Mazut oils in industrial instruments
Ash Corrosion

2. Masoud Nezhad Esmaeil Zadeh
Student number : 953130122
Relative Master :Dr. Rajabi
Babol Noshirvani University of
Technology
Specifications

3. Topics
Mazut Oil
Ash Corrosion’s Definition
Ash Corrosion’s Mechanism
Effective Factors
Solving This Problem

4. Mazut Oil
Hydrocarbon
length
Color
Applications
Flash
Point
Melting
Point

5. Corrosion Definition
Destruction and degradation of
matter due to the reaction to
the surrounding environment.
The choice of materials for the
desired applications depends
on various factors, one of
which is the resistance of the
material to the corrosion
phenomenon.

6. Ash Corrosion
POTASSIUM
SODIUM
VANADIUM
SULFUR

7. Appearance of Corrosion on Metal Surface
• Picture of a built cavity on metal surface
because of ash corrosion – Electronic
Microscope

8. Common Corrosions in Boilers
Corrosions
on External
Surface

9. Ash Corrosion Mechanism
High
Temperature
Corrosion
Sedimenting
Ashes
Production
of fuel
products

10. Effective Factors in Ash Corrosion
Phenomenon
1- Concentration of molten salts or fuel impurities, and the temperature
and chemical alloy’s composition
2- Fuel Type (The amount of fuel impurities) The amount of sulfur in
fuel and the temperature of the metal surface
3- alloy temperature be upper than produced melting point of composites
4- The rate of this type of corrosion is strongly dependent on the type
of alloy and its location in the furnace
5- unburnt Coal particles
6- Conditions for reducing gases

11. Solving This Problem
Cleaningtheoutside
surfaceofthe
componentsand
equipmentsuchas
superheatersand
theirretainingbelts.
SuitableMaterial
Choice
Use ofspring
supports
Temperature
control of metal
Correct spacing
between tubes
Addingadditivesto
the fueltoprevent
impuritiesfrom
burninghigh
temperature,such
as magnesiumcitrus
Removeharmful
impuritiesin the
fueland
environment
Thermomechanics
coating(thermal
spray)dependingon
the material

12. Chemical cleaning

13. Independent alloys to ash corrosion
phenomenon

14. Case Histories
Details
MATERIAL Steel (13 CrMo 9 10)
SYSTEM Oil-fired water-tube boiler
PART Superheating tube
PHENOMENON High-temperature corrosion
APPEARANCE External uniform attack leading
to cracking by superheating
TIME IN SERVICE 5 Years
ENVIRONMENT Deposit containing over 70%
sodium sulfate and 4% vanadium
oxide
Details
CAUSE The presence of oxides of heavy metals (V, W,
Nb) catalyzes the oxidation at high
temperature.
Heavy oil contains sulfur, vanadium, and
sodium. At wall temperatures above 600°C,
vanadium
oxide and sodium sulfate melts occur on the
superheater tubes, leading to corrosion of the
steel. This phenomenon is also known as hot
corrosion or in oil-fired boilers oil-ash corrosion.
Details
REMEDY Initially, dosing of various oil additives proved
ineffective; subsequently, for other reasons
as well, switched to firing sulfur-free natural
gas; the entire superheater was replaced.

15. Details
MATERIAL Austenitic stainless steel
(AISI 321; W.-Nr. 1.4541).
SYSTEM Coal-fired water-tube boiler
PART Secondary superheater outlet
tube
PHENOMENON High-temperature corrosion
APPEARANCE Pock-marked surface .The tube-
wall thickness had been reduced
TIME IN SERVICE 3 years continuous operation
ENVIRONMENT Flue-gases with fly-ash, from
combustion of coal
Analysis: ash 10%; O2 3%–4%;
S 7%; SO2 1200 ppm;
CO2 15%; SO3 1 ppm; CO 300
ppm.
Details
CAUSE Deposit of fly-ash on the superheater tubes.
With time, the volatile alkali and sulfur
compounds forming from the coal combustion
condense on the fly-ash and react with it to
form complex alkali sulfates such as K3Fe(SO4)3
and Na3Fe(SO4)3 at the metal–deposit interface.
The molten slag fluxes the protective oxide
covering of the tube, exposing the metal
beneath to accelerated oxidation: coal-ash
corrosion
Details
REMEDY • Corrosion monitoring by ultrasonic thickness
surveys.
• If corrosion is not severe, periodic tube
replacement, specification of thicker tube
walls, or use of thermal spray coatings may
be economic solutions.
• Where coal-ash corrosion is severe, cladding
of tubes with a resistant alloy may be
required.
Fuel additives have not been economically
successful. It may be valuable to blend coals to
reduce the percentage of corrosive
constituents and to lower metal temperatures.

16. Sources ‫احمد‬ ‫سيد‬ ،‫موسوی‬.‫پليمرها‬ ‫از‬ ‫استفاده‬ ‫با‬ ‫بخار‬ ‫و‬ ‫آب‬ ‫سيکلهای‬ ‫در‬ ‫گذاری‬ ‫رسوب‬ ‫از‬ ‫ممانعت‬.‫دومين‬ ‫برگزيده‬ ‫مقاﻻت‬ ‫مجموعه‬
‫برق‬ ‫و‬ ‫آب‬ ‫صنعتی‬ ‫دانشگاه‬ ،‫صنعت‬ ‫در‬ ‫نگهداری‬ ‫مديريت‬ ‫مهندسی‬ ‫سمينار‬1370.
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،‫نصيری‬ ‫سبا‬ ‫نيروگاه‬ ‫در‬ ‫مازوت‬ ‫سوخت‬ ‫احتراق‬ ‫از‬ ‫ناشی‬ ‫مکانيکی‬ ‫های‬ ‫آسيب‬ ‫و‬ ‫خوردگی‬

17. Thank You!
Masoud Nezhad Esmaeil Zadeh