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Contenu archivé le 2022-12-27

OPTIMIZATION OF ENERGY RECOVERY IN SLUDGE GENERATED BY A WASTE WATER TREATMENT PLANT

Objectif

The aim of the project is to recover as much as possible of the existing energy in the sludge generated by the Waste Water Treatment Plant and transform it into an energy that represents a higher cost both for the sewerage plant and for the country, i.e. electric power.
1. Using sludge to produce more power than the energy generated by anaerobic digestion. (14.496.000 kWh/year).
2. Efficiency : reduction of the present energy costs.
3. Improving the operating process.
4. Expected payback period of 4,7 years at this stage of the Sewerage Scheme.

INNOVATIVE TECHNOLOGY
The purpose is to transform the traditional sludge treatment process as applied in a typical Waste Water Treatment Plant in such a way that it preserves all the energy contained in the sewerage (organic matter), in order to achieve a subsequent autonomous incineration (without additional combustible). At this stage of the incineration process, the aim is not only minimizing the residual but also generating power and optimizing the process by means of cogeneration.
In short, the technology is innovative as it avoids anaerobic digestion and uses incineration to produce power. In this process, the sludge operates as a primary source of energy.
GENERAL DESCRIPTION OF THE PROJECT
The sludge resulting from the waste water is first dewatered in a filter press with an advanced monitoring and polymer dosage system, by means of which the dryness of the sludge can be increased up to 40% (35% with biological sludge). This dewatering process enables a spontaneous combustion of the sludge in the incineration kiln, due to the fact that the sludge conserves 100% of its energy as it has not been subject to anaerobic digestion. In order to achieve a spontaneous combustion the fluidized air must be at 150 deg. C.
The heat released from the combustion process in the incinerator is at 850 deg. C. The available energy in these fumes is recovered in a boiler that generates medium pressure steam, 40 kg/cm2, and reheated, 400 deg. C. The resulting steam can be used in a steam condensing turbine in order to generate power.
There are two points of external thermal energy demand in the incinerating and treatment process : on the one side, the fluidized air released from the incinerator must be heated from the ambient temperature up to 150 deg. C; on the other side, the steam at the outlet of the steam condensing turbine at 40 deg. C, must be raised up to 105 deg. C, i.e. the temperature needed for the degasifier. This thermal energy feed could be achieved usingpart of the steam produced in the boiler. However, the steam used for heating would stop passing through the steam turbine and, consequently, the amount of power generated by the turbine would decrease. In order to solve this problem, the Project considers using a piston-powered natural gas engine. In the one side, this engine allows generating electric power and in the other side, it will feed the necessary thermal energy into the process in such a way that it will be possible to generate additional electric power in the steam turbine.
COST ANALYSIS
- Total cost of the Project : Pesetas 821,4 million.
- Total cost of innovative application : Pesetas 371,4 million.
- Energy saving : 14.496.340 kWh/year.

Appel à propositions

Data not available

Régime de financement

DEM - Demonstration contracts

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IBERESE SA & CONTROL Y APLICACIONES INDUSTRIALES
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Espagne

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