Nav: Home

Siberian scientists learned how to reduce harmful emissions from HPPs

January 22, 2018

A team of scientists from Siberian Federal University (SFU) and their colleagues from Novosibirsk and the Netherlands modeled the process of coal burning in HPP boilers and found out which type of fuel produced less harmful emissions. The study was published in Fuel journal.

Heat power plants (HPPs) supply electrical energy to many cities in the world. The production of heat and electricity starts with burning coal in a combustion chamber. Generated heat warms up the steam and smoke mixture that moves the turbine. This is how electricity is produced, and the warmth is used for heating. However, when coal is burned at HPPs, harmful nitrogen oxides are released into the atmosphere.

One of the most prospective emission-cutting technologies is post-combustion or three-stage fuel combustion. After the first combustion stage during which the main part of the coal burns out and the air is scarce, the remains of the fuel are transferred to a special area above the combustion chamber. Additional fuel is also transported here. Nitrogen oxides react with the hydrocarbon forming hydrogen cyanide and molecular nitrogen, and the volume of nitrogen oxide emissions drops by about 10%.

"The environmental impact of oil and gas post-combustion is more evident, but we also have to work with coal. It has a great practical importance as many HPPs use it," explained Alexander Dekterev, a co-author of the article, candidate of technical sciences, and head of the department of thermal physics at SFU.

Many scientists conducted experiments in order to understand which properties of coal and combustion techniques allow for maximum emissions reduction. Recently physicists have offered to mill coal down not to average powder (with particle size of about 200 micron, like in facial powder) but to micro-particles (20-30 micron). This technique provides for a more stable flare in HPPs, as coal micro-particles are mixed better and burned quicker.

Previously this effect was demonstrated in small experimental boilers. The flame from the burning of coal micro-particles resembled that of burning oil, and the particles were almost invisible. Still it wasn't clear whether the effect would be the same in regular HPP boilers, and the scientists from Krasnoyarsk decided to model that.

They took a standard steam boiler BKZ-500-140 of Krasnoyarsk HPP-2 as a model, as all experimental data on it was available. The data were downloaded into the model and after that is was reconfigured taking the post-combustion into account. In the new model the basic fuel was brown Kansk-Achinsk coal, and the post-combustion fuel was formed by jet coal from Kuznetsk. According to initial calculations, the mathematical model implemented by the authors of the article in the in-house software correctly described the processes in the boiler.

The team modeled three burning schemes - with regular coal, micro-particle coal, and mechanically activated fuel. The latter variant proved to be preferable and led to 50% reduction in Nox emissions compared to the basic variant and by 20% to the regular coal.

The work might be of interest for developers and engineers working on the improvement of the existing boiler equipment and design of power blocks. The authors continue to develop mathematical modeling methods to improve burning technologies both for widely used and unconventional fuel types.

Siberian Federal University

Related Nitrogen Articles:

How nitrogen-fixing bacteria sense iron
New research reveals how nitrogen-fixing bacteria sense iron - an essential but deadly micronutrient.
Corals take control of nitrogen recycling
Corals use sugar from their symbiotic algal partners to control them by recycling nitrogen from their own ammonium waste.
Foraging for nitrogen
As sessile organisms, plants rely on their ability to adapt the development and growth of their roots in response to changing nutrient conditions.
Inert nitrogen forced to react with itself
Direct coupling of two molecules of nitrogen: chemists from W├╝rzburg and Frankfurt have achieved what was thought to be impossible.
Researchers discover new nitrogen source in Arctic
Scientists have revealed that the partnership between an alga and bacteria is making the essential element nitrogen newly available in the Arctic Ocean.
Scientists reveal impacts of anthropogenic nitrogen discharge on nitrogen transport in global rivers
Scientists found that riverine dissolved inorganic nitrogen in the USA has increased primarily due to the use of nitrogen fertilizers.
Nitrogen gets in the fast lane for chemical synthesis
A new one-step method discovered by synthetic organic chemists at Rice University allows nitrogen atoms to be added to precursor compounds used in the design and manufacture of drugs, pesticides, fertilizers and other products.
Nitrogen fixation in ambient conditions
EPFL scientists have developed a uranium-based complex that allows nitrogen fixation reactions to take place in ambient conditions.
New regulators of nitrogen use in plants identified
Researchers have identified a set of gene regulators in plants that could help plants utilize nitrogen better, which would prevent ecological damage from excess nitrogen in the soil.
Boxing up ag field nitrogen
Scientists develop edge-of-field practices so growers can keep the early planting offered by the tile drains while protecting nearby streams-and the Gulf of Mexico-from nitrate contamination.
More Nitrogen News and Nitrogen Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#538 Nobels and Astrophysics
This week we start with this year's physics Nobel Prize awarded to Jim Peebles, Michel Mayor, and Didier Queloz and finish with a discussion of the Nobel Prizes as a way to award and highlight important science. Are they still relevant? When science breakthroughs are built on the backs of hundreds -- and sometimes thousands -- of people's hard work, how do you pick just three to highlight? Join host Rachelle Saunders and astrophysicist, author, and science communicator Ethan Siegel for their chat about astrophysics and Nobel Prizes.