Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Sewage Sludge Incineration Plant Generates its own Energy

24.09.2015

The world’s largest plant for the incineration of sewage sludge is now nearly energy-neutral. With two newly installed steam boilers and one steam turbine, it is generating at least 95 percent of its power requirements from the waste heat of the incineration process itself. Operating costs have been reduced by nearly 10 percent.

Until now, the plant only generated low-pressure steam from the waste heat. The steam is used in various processes and, to a limited extent, for power generation.


The boiler is ready to be hoisted into the facility.


The location for the new boiler. Part of the roof is taken off so the boiler can be hoisted into place.

Boiler specialist NEM, owned by Siemens and operating under its own brand, has now replaced two of the four low-pressure steam boilers with high-pressure boilers and has installed a turbine that generates electricity via a generator. This makes it possible for the operator to use the exhaust heat much more efficiently and produce nine times more power than before.

Recovering Raw Materials

In Germany alone, about eight million tons of dewatered sewage sludge accumulates every year. Around one third of the sludge is used for agriculture, a share that has stagnated for years due to the increased quality requirements for sewage sludge.

Incineration is therefore becoming increasingly attractive, either in specialized plants or as additional fuel in cement plants, coal-fired power plants, and waste incineration plants. Dedicated plants that only incinerate sewage sludge offer the advantage that valuable raw materials contained in the sludge, particularly phosphorous, can be separated and reused as fertilizers.

In the Netherlands, N.V. Slibverwerking Noord-Brabant (SNB) operates this type of dedicated plant and processes approximately 450,000 tons of dewatered sewage sludge every year. The dried sludge is incinerated at a temperature of approximately 900 degrees Celsius.

Waste heat is used more efficiently and phosphorous is recovered as fertilizer


Customized Boiler

When the SNB plant was retrofitted with two high-pressure steam boilers for power generation, engineers from boiler specialist NEM, which became part of Siemens in 2011, faced two challenges. They had to design the boilers so they could fit into the plant, which was built in 1997. In addition, the boilers had to be installed as quickly as possible while the plant was in partial operation so as not to disrupt processing of sewage sludge.

Experts implemented a boiler that meets the specifications for the turbine (450 degrees Celsius steam temperature at a pressure of 60 bar) while also complying with prescribed restrictions for size and weight. They achieved this in part by using a smaller diameter for the boiler’s economizer tubes, which allowed them to reduce wall thickness and hence weight.

In addition, it was necessary to adjust the spacing of pipes in accordance with height restriction while at the same time taking into account the fouling characteristics of the fuel. Engineers had to pay special attention to the selection of steam temperature. Sewage sludge contains many different chemical elements, some of which corrode metal at very high temperatures. That’s why the steam temperature was limited to 450 degrees Celsius even though the boilers and turbine would be able to operate at higher temperatures.

The steam drives a Siemens SST 110 industrial steam turbine. The turbine has two modules connected in parallel. A high-pressure module is operated at a steam pressure of 60 bar. After this, a low-pressure module supplies the remaining steam in the form of process steam at a pressure of 2.5 bar.

This low-pressure steam is used primarily to dry the sewage sludge, which contains approximately 75 percent water upon delivery. Retrofitting with high-pressure boilers eliminated the steam motor operated with low-pressure steam that had previously been used to generate electricity with a 450-kilowatt generator. Instead, the plant now uses a 3.5-megawatt generator to cover nearly all of its power requirements.Bei der Nachrüstung der SNB-Anlage mit zwei Hochdruck-Dampfkesseln.

Norbert Aschenbrenner


Contact

Mr. Dr. Norbert Aschenbrenner

Editorial Office

Siemens AG
norbert.aschenbrenner@siemens.com


Mr. Florian Martini

Press contact

Siemens AG
florian.martini@siemens.com

Dr. Norbert Aschenbrenner | Siemens Pictures of the Future
Further information:
https://www.siemens.com

More articles from Power and Electrical Engineering:

nachricht Researchers use light to remotely control curvature of plastics
23.03.2017 | North Carolina State University

nachricht TU Graz researchers show that enzyme function inhibits battery ageing
21.03.2017 | Technische Universität Graz

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Northern oceans pumped CO2 into the atmosphere

27.03.2017 | Earth Sciences

Fingerprint' technique spots frog populations at risk from pollution

27.03.2017 | Life Sciences

Big data approach to predict protein structure

27.03.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>