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 Laser sensor LAH-G1 - optical distance sensors with measurement value display
15.08.2017 | WayCon Positionsmesstechnik GmbH

nachricht Engineers find better way to detect nanoparticles
14.08.2017 | Washington University in St. Louis

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: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>