The bioenergy plant burns 115,000 to 120,000 te of wood per year and generates 67 te/hr of superheated steam at 84 barg. The steam passes through a condensing turbo generator, generating 17.4 MW/hr of electricity, enough to power up to 20,000 homes through the national grid.
The plant suffered heavy fouling of the furnace walls and tubes. The extremely hard build-up was so significant that large heavy deposits were falling on and damaging the feed grates. This resulted in unplanned outages of four to five days to clean up and replace the grates.
Magnesium based slurries and clay technology were unsuccessfully applied so the plant wats looking for a way to eliminate unplanned grate failures (three to five per year) due to falling slag.
SUEZ Water Technologies & Solutions offered an expansive FuelSolv FS3954 treatment to limit boiler fouling and to reduce the number of shutdowns for cleaning over the operating period.
A laboratory sintering test on sample ash from the furnace area of the boiler showed the positive effect of FuelSolv FS3954 when applied above 1% at a temperature of 750˚C (1380˚F).
Due to the rate of ash generated by this type of feedstock, SUEZ recommended a dosing rate of 100g of FuelSolv FS3954 per ton of waste incinerated.
FuelSolv FS3954 consists of non-hydroscopic particles that are injected into the boiler using a compressed air feed system.
In the test, chemical was fed through a single injection point, directly into the boiler furnace (via the secondary air-port).
The site personnel noticed a significant change to the bottom ash removed from the boiler. It changed from very hard to a friable, granular composition.
No failure of the grate has occurred since the treatment was introduced.
Furnace cleanliness has improved with existing deposits being reduced by the addition of FuelSolv FS3954.
When viewing the furnace from an inspection port to a daily basis, the customer was surprised that no further build-up had occurred and in fact, the existing deposits were reduced.