Puiduhakke põletamisel tekkivate lämmastikoksiidide heitmete vähendamine
| dc.contributor.advisor | Eha, Kaie | |
| dc.contributor.author | Tiedemann, Karl | |
| dc.date.accessioned | 2024-06-03T07:02:35Z | |
| dc.date.available | 2024-06-03T07:02:35Z | |
| dc.date.issued | 2024-05-15 | |
| dc.description.abstract | Antud lõputöö eesmärgiks oli tuua välja olemasolevad lämmastikoksiidide heitmete vähendamise meetodid, võrrelda nelja Eesti suurima koostootmisjaama juba kasutusele võetud NOx heitmete vähendamise protsesse ja võrrelda neid kirjanduses välja toodud parimate praktikatega. Eesmärgi saavutamiseks analüüsiti Eesti nelja suurima koostootmisjaama keskkonnakomplekslube ja võrreldi seda eelnevalt uuritud erialasest kirjandusest koostatud kirjanduse ülevaatega. NOx heitmed tekivad praktiliselt kõikides põlemisprotsessides. NOx ühendid avaldavad negatiivset mõju looduskeskkonnale, põhjustades näiteks osoonikihi hõrenemist, happesademeid ja eutrofeerumist. Osoonikihi hõrenemise tõttu on maapinnale langev UV kiirgus suurem, mis mõjutab nahavähi esinemise kasvu. Happesademed ja eutrofeerumine mõjutavad veekogude ökoloogilist tasakaalu ning NOx ühendite kõrge kontsentratsioon sissehingatavas õhus võib põhjustada hingamisteede haigusi ning tekitada silmade ärritust. Lämmastikoksiidide heitmete vähendamise meetodeid puidu põletamisel on kahesuguseid: primaarsed meetmed ning sekundaarsed meetmed. Primaarseid meetodeid rakendatakse põlemisprotsessi ajal ning neist enim kasutatavamad on õhu astmeline lisamine ja suitsugaaside ringlus. Sekundaarmeetmeid SCR ja SNCR rakendatakse aga põlemisprotsesside järgselt. Eesti nelja suurima koostootmisjaama (Mustamäe, Lohkva, Pärnu ja Väo 1.) NOx heitmete mõõtmistulemused jäävad alla seadusandlusega määratud piirväärtusi. Seega võib oletada, et kasutatavad vähendamise meetmed on piisavalt tõhusad. Kui Lohkva, Pärnu ja Väo 1. koostootmisjaamad kasutavad nii primaar- kui ka sekundaarmeetmeid, siis Mustamäe käitises kasutatakse ainult primaarmeetmeid. Teisalt, arvestades Mustamäe jaama kõrgeid NOx heitmete mõõtmistulemusi, võiks sekundaarmeetmete rakendamine neid oluliselt vähendada. Erinevusi kirjanduses esitatu ja analüüsi tulemuste vahel ei esinenud. Teisalt leiti sekundaarmeetmete uuenduslikke tehnoloogiaid TWIN-NOx® ja selektiivne suitsugaaside jahutamine, mida ei kasutata veel Eestis. Soovides jääda tulevastesse piirmääradesse, tuleks siiski hakata planeerima nende rakendamisvõimalusi. | |
| dc.description.abstract | The European Union (EU) is making it mandatory for renewable energy to account for at least 32% of total energy consumption by 2030, forcing Member States to increase the share of renewable energy. To achieve this, the heating and cooling sector will need to reduce its use of fossil fuels and the use of biofuels, including solid biomass, will be an important component of the EU's heating and cooling strategy. In 2017, solid biomass energy accounted for 43% of the energy produced for the residential sector in the EU. The use of solid biomass is attractive not only because of its high share of renewable energy in heat production, but also because of its lower energy costs compared to fossil fuels. It can help to reduce carbon dioxide emissions and act as an alternative to fossil fuels as a renewable and carbon neutral energy source. The combustion of solid biomass for heat production can reduce environmental sustainability by directly affecting air quality. The main pollutants in this context are particulate matter (PM) and nitrogen oxides (NOx). Particulate emissions are often considered as the main source of air pollution, leading to increasingly stringent restrictions on the use of biomass heating installations. Although NOx emissions have received less attention, studies show that a large part of the environmental impact of modern biomass heating systems can be attributed to NOx emissions. The aim of this thesis is to identify the existing methods for reducing NOx emissions, to compare the NOx emission reduction processes already implemented by the four largest cogeneration plants in Estonia and to compare them with the best practices reported in the literature. In order to achieve the objective, the following research questions have been set: • What are the impacts of NOx on the natural environment and humans? • What are the methods for reducing nitrogen oxide emissions from wood combustion? • How are nitrogen oxide emissions reduced in wood combustion? What are the processes for reducing nitrogen oxide emissions in the four largest cogeneration plants in Estonia? NOx emissions are produced in virtually all combustion processes. NOx compounds have a negative impact on the natural environment, for example by causing ozone depletion, acid deposition and eutrophication. Due to ozone depletion, the UV radiation incident on the ground is higher, which influences the increase in skin cancer. Acid deposition and eutrophication affect the ecological balance of water bodies, and high concentrations of NOx compounds in inhaled air can cause respiratory diseases and eye irritation. There are two types of methods to reduce NOx emissions from wood combustion: primary measures and secondary measures. Primary methods are applied during the combustion process and the most commonly used are staged air injection and flue gas recirculation. Secondary measures SCR and SNCR, on the other hand, are applied after the combustion processes. The four largest cogeneration plants in Estonia (Mustamäe, Lohkva, Pärnu and Väo 1.) have NOx emissions below the limit values set by legislation. It can therefore be assumed that the abatement measures used are sufficiently effective. While the Lohkva, Pärnu and Väo 1. cogeneration plants use both primary and secondary measures, the Mustamäe plant uses only primary measures. On the other hand, given the high NOx emission measurements at Mustamäe, the implementation of secondary measures could significantly reduce them. There were no discrepancies between the literature and the results of the analysis. On the other hand, TWIN-NOx® and selective flue gas cooling were found to be innovative technologies for secondary measures, which are not yet used in Estonia. However, in order to stay within future thresholds, it would be worthwhile to start planning for their application. | |
| dc.identifier.uri | https://dspace.tktk.ee/handle/20.500.12863/5313 | |
| dc.language.iso | et | |
| dc.publisher | Tallinna Tehnikakõrgkool | |
| dc.subject | Keskkonnatehnoloogia | |
| dc.subject.other | Keskonnatehnoloogia ja -juhtimine | |
| dc.title | Puiduhakke põletamisel tekkivate lämmastikoksiidide heitmete vähendamine | |
| dc.title.alternative | Reduction of Nitrogen Oxide Emissions from Biomass Combustion | |
| dc.type | lõputöö |