Process

Process of thermal sewage sludge utilisation sludge2energy

 

1 - sludge storage tank (wet) 2 - sludge storage tank (dry) 3 - belt dryer 4 - mixer and conveyor 5 - fluidised bed reactor 6 - combustion air preheater 7 - hot water boiler 8 - reserve for heat exchanger 9 -  fabric filter 10 - chimney 11 - ash containers / silos 12 - sodium bicarbonate, activated carbon, dosing 11 - ash containers / silos 13 - sand 14 - ammonia water 15 - natural gas 16 - heat exchanger 17 - combustion blower

Technical description

  • Sludge tank (1) for sewage sludge storage (compensation of production variations)
  • Wet sludge delivery by thick material pumps
  • Belt dryer (3) with pelletiser and heat supply from combustion
  • Condensation of dryer vapours, introduction of vapours/air into the fluidised bed furnace (5) as combustion air
  • Intermediate storage (2) of dried sewage sludge
  • Mixing (4) of dried and dewatered sewage sludge and grit (13), feeding of fluidised bed furnace (5) after milling and pneumatic input
  • Fluidised bed furnace (5) with open perforated plate bottom to remove disturbing material and control grit quality in the fluidised bed
  • Boiler with two radiation strings and one or two convection strings with heat exchanger bundles (5,6,7)
  • Heat utilisation for flue gas for combustion air preheating (6) and hot water boiler (7) for heat supply to the belt dryer (and optionally external consumers)

 

  • The combustion air pre-warmed with hot water in the belt dryer (3) is compressed by the combustion air blower (17) and pre-heated in the air preheater (6) before injection into the fluidised bed.
  • The combustion air can be injected at three levels. Also recirculated flue gas can be used to have a constant control of the combustion process.
  • Ammonia water is injected (14) in the combustion chamber according to the Selective Non Catalytic Reduction (SNCR) method as first stage of flue gas cleaning for denitrification.
  • Dry scrubber (12) as second flue gas cleaning step with sodium bicarbonate for dechlorination and desulfurisation as well as activated carbon to bind dioxins and heavy metals (e.g. Hg).
  • Fabric filter (9) for removal of dust and sorbents from the flue gas
  • Measurement station for the control of all legal emission limits
  • Filter ash discharge is separate from combustion bed and boiler ash and stored in different containers (11).

1 Sludge Storage Tank (wet)

1 Sludge Storage Tank (wet)

Sludge tank for sewage sludge storage (compensation of production variations).
Wet sludge delivery by thick material pumps.

Sludge storage tank (wet)

2 Sludge storage tank (dry)

2 Sludge storage tank (dry)

Intermediate storage of dried sewage sludge

3 Belt Dryer

3 Belt Dryer

Belt dryer with pelletiser and heat supply from combustion

HUBER Belt Dryer BT

4 Mixer and conveyor

4 Mixer and conveyor

Mixing of dried and dewatered sewage sludge and grit (13), feeding of fluidised bed furnace (5) after milling and pneumatic input

5 Fluidised bed reactor

5 Fluidised bed reactor

Fluidised bed furnace with open perforated plate bottom to remove disturbing material and control grit quality in the fluidised bed.
Boiler with two radiation strings and one or two convection strings with heat exchanger bundles.

6 Combustion air preheater

6 Combustion air preheater

Heat utilisation for flue gas for combustion air preheating.

7 Hot water boiler

7 Hot water boiler

Heat utilisation from flue gas to heat water for heat supply to the belt dryer (and optionally external consumers).

9 Fabric filter

9 Fabric filter

Fabric filter for removal of dust and sorbents from the flue gas.

Additional measurement station for the control of all legal emission limits.

11 Ash containers / silos

11 Ash containers / silos

Filter ash discharge is separate from combustion bed and boiler ash and stored in different containers.

12 Sodium bicarbonate, activated carbon, dosing

12 Sodium bicarbonate, activated carbon, dosing

Dry scrubber as second flue gas cleaning step with sodium bicarbonate for dechlorination and desulfurisation as well as activated carbon to bind dioxins and heavy metals (e.g. Hg).

14 Ammonia water

14 Ammonia water

Ammonia water is injected in the combustion chamber according to the Selective Non Catalytic Reduction (SNCR) method as first stage of flue gas cleaning for denitrification.

17 Combustion air blower

17 Combustion air blower

The combustion air pre-warmed with hot water in the belt dryer (3) is compressed by the combustion air blower and pre-heated in the air preheater (6) before injection into the fluidised bed.