sludge2energy Process Variant Steam Boiler

With this design version „Steam Boiler“, the exhaust heat is made available for utilisation on a higher energy level in the form of power and steam.

   1  Sewage sludge acceptance and storage
  2  Sewage sludge drying with contact dryer
  3  Condensation stage
  4  Storage tank for vapour condensate
  5  Sludge logistics and input
  6  Stationary fluidized bed furnace
  7  Waste heat steam boiler
  8  Pre-separation ash / fabric filter
  9  Dry sorption / reactor
10  Fabric filter for exhaust air treatment
 11  Two-stage scrubber
12  Chimney, emission control
13  Phosphate-containing ash
14  Residue logistics
15  Sorbent dosing
16  Steam turbine, power generator

Process description

The resulting sewage sludge is processed on a process line consisting of the steps sludge reception, sludge drying, combustion, waste heat boiler and downstream flue gas cleaning.

Disc dryers (so-called contact dryers) are used for drying the sewage sludge. These dryers provide homogeneous partial drying to approx. 45 % dry residue (DR), which enables the self-sustaining combustion of the sewage sludge in the furnace. The subsequent thermal utilization of the sewage sludge takes place in a stationary fluidized bed incinerator according to the sludge2energy process with the S2E Fluidizer.

In the waste heat boiler, the energy from the flue gas is converted into usable steam and thus made further utilizable. The energetic utilization of the steam produced in the boiler plant takes place via a steam turbine with generator. In addition, the exhaust steam available in the boiler plant supplies the sewage sludge drying plant and all other internal heat consumers with the required heat. Further excess steam can also be directed to a district heating condenser, where it condenses; the thermal energy can then be transferred to a public district heating network. Thus, the energy contained in the steam can be optimally utilized.

The flue gas is cleaned in a multi-stage, wastewater-free flue gas purification plant using state-of-the-art technology. The concept for flue gas cleaning meets the requirements of modern sewage sludge incineration and clearly stays below the legal requirements and limit values.

The phosphorus-containing ash from the pre-separation process is available for phosphorus recovery together with the low-pollutant sewage sludge ash produced in the boiler.

Performance range of the "steam boiler" process:

  • Fuel heat output per line: 3.5 to 18 MW
  • Throughput of dewatered sewage sludge: approx. 11,000 to 50,000 t DS/a
  • Input dry residue content: approx. 25 % DR
  • Organic content of dry matter: approx. 60 % oDS