Reduce emissions and increase operational efficiency with Therma-Chem’s unique online boiler cleaning solutions.

Online Boiler Cleaning Specialists
Therma-Chem have been providing online boiler cleaning services for coal-fired units since 1984. Our unique product, FS12, is a post-combustion treatment of ash deposits which eliminates slagging and fouling throughout the boiler resulting in increased efficiency, reduced emissions and the prevention of corrosion.
Therma-Chem FS12 has been recognised by the United Nations as an approved methodology for reducing carbon emissions and we are extremely pasionate about helping our clients reduce their impact upon the environment.
The above images show a substantial reduction of slagging on the superheater tubes of a lignite-fired 330MW boiler.
How FS12 Benefits Boiler Performance
thermachem boiler diagram - Coal-Fired Power Plant


Eliminate slagging and improve
heat transfer.

FS12 removes slagging from the tube walls and converts it to dry, friable powder. This results in increased heat transfer and restored capacity.


Prevent high temperature corrosion


Limit fouling and maintain flue gas velocity


Improve performance and reduce maintenance


Prevent dew point corrosion from sulphuric acid


Improve particulate removal and reduce cleaning time


Reduce NOx, SOx and
Carbon emissions


Improve performance and
prevent corrosion

How Does FS12 Work

Therma-Chem’s FS12 is a mildly alkaline solution containing nitrates that is designed specifically to clean boilers online. Using Therma-Chem’s proprietary injection system, the liquid is injected directly into the combustion chamber, vaporises and is carried by the flue gas through the unit, encountering all heat transfer surfaces including the waterwalls, superheaters, economiser and air pre-heater.

FS12 reacts with existing hard deposits and fouling on tubes by increasing their melting point and reduces them to soft powdery ash.

This allows units to maintain high thermal efficiencies or recover capacity (if this was limited by fouling). FS12 also neutralises sulphur deposits on the cold end of the flue gas path preventing cold end corrosion and eases man entry during a maintenance or inspection shutdown.

In addition, FS12 will reduce NOx, SOx and Carbon emissions via efficiency improvements.

Using FS12 ultimately results in improved heat transfer, prevention of both high temperature and low temperature corrosion, improved operating efficiency and reduced emissions.

The above images show a substantial reduction of ash deposits on the superheater tubes of a UK coal-fired boiler.
Application Methods
FS12 is traditionally applied to process heaters in one of three ways


Applied daily, FS12 keeps units clean and prevents costly drop offs in performance and avoids the possible need for shutdowns during the operating campaign. This is the most common method of application with some customers having used Therma-Chem every day for 15 years across multiple units.


When a unit is load and/or temperature restricted mid-run and there is no window to shut down for maintenance, FS12 is introduced to recover performance. Injected 3-4 times per day over a period of 30-90 days, depending on the severity of the fouling, FS12 can target any part of the unit loosening deposits and restoring performance. We would then recommend switching to Maintenance Dosing to prevent a drop-off in performance recurring.


Utilised in the run up to a shutdown to facilitate a more effective and easier clean of a unit, FS12 can be applied 3-4 times per day for a period between 30 – 90 days.This ensures that during the shutdown, cleaning is more effective, easier, quicker and any sulphuric deposits are neutralised, dry, and entry into all areas of the unit is safe and comfortable.