Gas-Fired Power Plants

Recover efficiency losses in boilers and HRSGs via online cleaning.

Gas-Fired Boilers

Online Boiler Cleaning Specialists

Gas-fired boilers do not experience significant levels of ash deposition due to the fuel composition. Nevertheless, there are still small percentages of elements and compounds which can lead to fouling resulting in a small loss of efficiency over the operating period.

Therma-Chem have significant experience in recovering small efficiency losses on gas-fired boilers in both power plants and refineries resulting in reduced fuel consumption and greater output. Furthermore, Therma-Chem specialise in eliminating any sulphur deposits prior to planned shutdowns. Even trace amounts of sulphur in the fuel can build-up over an extended run-time and Therma-Chem’s ability to eliminate this protects metallurgy and makes boilers safer to clean.


Eliminate fouling and corrosion

On CCGT Power Plants, many of the HRSGs experience fouling which can restrict heat transfer and limit output. Moreover, because of the lower temperatures, any sulphur present in the fuel can lead to under-deposit corrosion causing damage to the tubes.

Therma-Chem can be injected online, downstream of the gas turbine, to target any fouling in the HRSG. Our unique ability to inject chemicals without line of site of the fouled areas, makes our solution unique for cleaning HRSGs. Not only we will we minimise fouling and increase the efficiency of the unit, we will also eliminate any sulphuric acid deposits protecting the integrity of the unit and ensuring that there is easy access at turnarounds.


After Therma-Chem treatment the hard deposits were removed from the radiant section and all sulphurous deposits were eliminated from the economiser and air pre-heater. As a result, boiler efficiency improved by 0.65% – equivalent to a third of the total efficiency loss prior to treatment.

Managing Director
Gas-Fired Power Station

How FS12 Benefits Boiler Performance

How Does FS12 Work

Therma-Chem’s FS12 is an 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.

Therma-Chem FS12 was injected in the lead up to a shutdown on a gas-fired boiler to eliminate any deposits and neutralise sulphur corrosion. As can be seen from this photograph, deposits were minimal, soft, and easy to remove with no evidence of corrosion.

Application Methods

FS12 is traditionally applied to process heaters in one of three ways:

Maintenance Dosing

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.

Online Recovery Cleaning

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.

Pre Shutdown Cleaning

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.