On the down-comer from the cyclone on a fluidized bed boiler, there is an expansion joint to take the axial expansion of the duct.
The normal design is a standard fabric expansion joint, with upstands of the refractory lined duct. This system operates well for a short period of time, but due to high ash content in the duct, a seizing up of the joint cavity soon takes place. This blocking of the joint imposes large forces into the ducting causing cracking.
DEKOMTE have worked on an engineering solution which surpasses the lone function of the fabric component, and considers how to develop an envelope of space allowing movement of the duct. The introduction of sealing air as part of the internal refractory and flow plate design, ensures space for the axial compression of the joint.
DEKOMTE have in service many joints which are functioning for over 10 years with no maintenance.
Installation location of expansion joint
Mlada Boleslav
Ville Berrenrath
Design solution: expansion joint with aerodynamic ash barrier
|
Pipe temperature |
900°C |
| Movement | axial: 120 mm (expansion) lateral: ± 20 mm |
DEKOMTE solution with single-level aerodynamic sealing:
- permanent air sealing,
- in operation since beginning of 2002.
Permanent sealing air (75 mbar, 0,59m³/s)
Temporary extraction (0,59m³/s)
Flue gas / Ash down pipe
Operating Conditions:
| Pipe temperature | 870°C |
| Movement | axial: 190mm (expansion) lateral: ±10 mm |
DEKOMTE solution with double-level additional aerodynamic sealing:
- minimised amount of permanent sealing air,
- temporary sealing air,
- in operation since beginning of June 2006.
Permanent sealing air (40 mbar, 0,1m³/s) Temporary sealing air (75 mbar, 0,59m³/s) Temporary extraction (0,59m³/s) Flue gas / Ash down pipe
Manometer connections
Expansion joint design
- Refractory
- Permanent sealing air
- Inlet frame
- Fabric expansion joint
- Inner floating sleeve
- Suspension of segmented floating sleeve
- Segmented floating sleeve
- Temporary extraction
- Refractory
Expansion joint design
- Refractory
- Temporary sealing air
- Inlet frame
- Fabric expansion joint
- Inner floating sleeve
- Segmented floating sleeve
- Permanent air supply for expansion joint bellow
- Temporary extraction
- Refractory
Installed DEKOMTE Solution
Ville Berrenrath / RWE
DEKOMTE fabric expansion joint as a compensation element with aerodynamic ash barrier in a cyclone down pipe of a fluidized-bed boiler
