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CASE STUDY

VACUUM TAR RESIDUE
AND FUEL GAS
FIRED BOILER

JAPAN

VACUUM TAR RESIDUE AND FUEL GAS FIRED BOILER

160 MW boiler (630 T/Hr) firing a mixture of Vacuum Tar Residue and Fuel Gas
Problem

The boiler experienced heavy fouling on their superheaters and economiser causing flue gas temperatures to increase. This resulted in the boiler having to be shut down earlier than anticipated. In addition, they experienced corrosion on the air preheater extending maintenance time and jeopardising the metallurgy.

After Therma-Chem Treatment

Fouling was removed from both the superheaters and the economiser significantly reducing the flue gas exit temperature. This enabled the refinery to run the boiler for longer than they were previously able to. Corrosive sulphur deposits were neutralised in the air pre-heater enabling a more efficient and quicker clean at shutdown. The pictures to the right clearly show significant sulphur deposits on the APH baskets and carbonaceous deposits on the walls. After Therma-Chem treatment, these sulphur deposits have been converted to non-corrosive sulphites and sulphates and the carbonaceous deposits have been oxidised from the wall.

Therma-Chem have also had a significant impact upon the operation of the ID Fan. Prior to FS12 injections, the trend is of increasing ID fan amps. However, after treatment it is clear that the ID fan amps are relatively stable. ESP performance also improved requiring less maintenance and downtime for cleaning resulting in significant savings by returning the boiler to full load earlier than anticipated. The pictures to the right illustrate the difference in the cleanliness, and thus effectiveness, of the electrodes before and after Therma-Chem treatment. As a result of the improved boiler condition, the plant no longer need to use a magnesium oxide fuel additive and intend to increase the ratio of fuel oil to fuel gas burning, realising significant savings by burning cheaper fuel.

Flue gas temperatures before and after Therma-Chem treatment
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Air Pre-Heater before and after Therma-Chem treatment
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ID Fan amps before and after Therma-Chem treatment
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ESP electrodes before and after Therma-Chem treatment
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Vacuum Tar Residue
and Fuel Gas Fired Boiler

Japan

High flue gas temperatures
and APH corrosion

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HFO Fired Boiler

Saudi Arabia

Poor boiler efficiency and high
CO2 emissions

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Coal Fired Boiler

Romania

Loss of boiler efficiency and
high CO2 emissions

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Gas and HFO
Fired Boilers

Egypt

Efficiency loss due to fouling on
superheaters and economiser

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Expander in FCC Unit

South Korea

Catalyst deposits on rotating
blades causing severe vibration

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Shipping – LNG Tanker

Malaysia

Heavy deposits on combustion
and radiant sections of boilers
as well as back-end corrosion

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Process Heater

Belgium

Heater temperature limited
due to fireside conditions

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Process Heater

Singapore

Radiant temperature and
heater duty limited by fouling

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Gas Fired Reformer

UK

Unsustainable flue gas
temperature increase
due to fouling