Boilers upgrade from layered combustion to CBF
Refurbishment of standardised layered combustion boilers with a shift to the new promising CBF soil fuel combustion technology makes it possible to increase the boiler efficiency by 50% (by increasing heat exchange in the fluidised bed and installing additional areas), producing more heat from the same boiler house area.
The CBF technology makes it possible to retain the conventional design of the boilers, the slag and ash removal system and the automation almost completely during the refurbishment, significantly reducing the overall costs of the works. The boiler location does not change with the refurbishment; it remains in its place and does not touch the auxiliary devices.
CBF boilers have the following advantages:
- renovation of obsolete equipment
- fuel saving measures
- applicability of cheap fuels of inferior quality
- adherence to environmental limits on harmful pollutants to the air
Part of the CBF combustion chamber mobile ribbed grate
A refurbishment of a layered combustion boiler involves the following tasks:
- project design (2-3 months) in accordance with all the customer requirements
- manufacturing of the entire refurbished equipment (about 3-4 months)
- installation work (3-4 months)
The boiler upgrade to CBF can be made with a simple refurbishment, involving:
- replacement of the wide layered combustion chamber with a narrow one (composed of standardised grate ribs, i.e., combustion chamber with a belt grate and disperser, mechanical, as well as shafts and transmission mechanisms)
- installation of the CBF combustion chamber in the ash area (if it exists), increase the chamber height
- installation of front and rotary pipe walls for the heating chamber
The CBF technology makes it possible to retain the conventional design of the boilers, the slag and ash removal system and the automation almost completely during the refurbishment, significantly reducing the overall costs of the works. The boiler location does not change with the refurbishment; it remains in its place and does not touch the auxiliary devices.
Conventional layered combustion chambers require pneumomechanic dispersers (some of the least reliable mechanisms) for an even distribution of fuel across the entire area of the wide grate.
Since in the CBF combustion takes place on a narrow grate, CBF boilers are equipped with simple pneumogrativational feeders without dispersers for fuel supply. The fluidised bed itself evenly distributes and mixes the fuel fed.
Case studies – Boilers upgrade from layered combustion to CBF:
| Před rekonstrukcí | Po rekonstrukci | Změna hmotnosti | |
|---|---|---|---|
| Weight of combustion chamber with feeder and actuator, t | 27,0 | 12,0 | -15,0 |
| Weight of piping, t | 41,2 |
Extension of: two side pipe walls; front pipe wall; rear combustion chamber pipe wall, irrigation pipes |
+2,0 +1,0 +1,3 +1,0 |
| TOTAL: Boiler weight change, t | -9,7 |
Of course refurbishment to CBF can be made with continuing coal combustion with a high gross efficiency.
Of course refurbishment to CBF can be made with continuing coal combustion with a high gross efficiency.
The application of the technology of solid fuel combustion in a high-temperature circulating fluidised bed (CBF) has been expanding in recent years, even in industrial power generation, thanks to the possibility of using quite a broad range of cheap local fuels of inferior quality.
Operation of boilers with CBF combustion chamber does not pose any demanding requirements on operating staff qualifications, and virtually does not differ from standardised layered combustion boilers, does not require special training, only a brief practical learning-in.