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Development of selective oxidation technology for nox emission reduction in gasification power plants

Objective



The objective of this research project is to further develope new method, which can be used to rcduce substantially NOx emission originating from fuel bound fixed nitrogen in gasification power plants. This method is based on controlled and selective oxidation of fixed nitrogen species of the gasification product gas to N2 during gasification and hot gas cleaning. The central part of this project is the development of the new SCO (Sclective Catahtic Oxidation) technology. In the project new information is created with regard following questions and topics:
- How and to which extent the formation of nitrogen compounds can be minimized by gasifier design and by choosing such operational conditions that most of the fuel nitrogen is oxidized to N2.
- Development of SCO technology for hot gas cleaning
- The effect of SCO on gas combustion and the integration of SCO to the IGCC process
Main tasks are:
1. Control and removal of nitrogen compounds in gasifiers.
In this task the minimization of the conversion of fuel nitrogen to nitrogen compounds (NH3, HCN, NO, N2O) is investigated. The effect of gasifier design and operating conditions on the conversion of fuel nitrogen to nitrogen compounds are studied with laboratory scale and pilot scale gasifiers. Main emphasis is on the effect of air feeding, distribution and mixing in the fuel bed and gasifier freeboard.
Special emphasis is paid also to the formation of oxides (NO, N2 O) during gasification and lhe effect of gasifier operating parameters on these. This information is needed as an input to the task 2.
2. Selective Catalytic Oxidation (SCO)
In earlier laboratory experiments large NH3 reduction has been achieved in gasification gas flowing through aluminium oxide bed in the temperature range of 350-600 C. Selective NH3 removal reactions have been initiated by the addition of small amounts of reactive oxidizers to the hot gas. New simple and economic NH3 removal method could be based on these results. However, several questions concerning the feasibility of the SCO process are still open. These questions deal with the mechanism and optimization of the NH3 reduction and the effect of various gas impurities on the reactions.
This task deals with the further development of the SCO process
3. Combustion
In the SCO process part of the NH3 may be oxidized to NO, N20 and NO2 and remain in the hot gasification gas. These residual oxides together with residual NH3 will flow to the gas burner and react during various stages of combustion. The final emission to the atmospere can be determined only after these reactions.
Combustion experiments will be carried out to clarify the effect of SCO process on the combustion chemistry of low calorific value gas.
4. Modeling and evaluation
With modelling of oxidation reactions more information is created, which can be used to optimize the NH3 removal and NOx emission reduction. Technical and economic evaluation is carried out with regard to the feasibility of the SCO process.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Technical Research Centre of Finland
Address
Biologinkuja
02044 Espoo - Vtt
Finland

Participants (4)

AABO AKADEMI UNIVERSITY
Finland
Address
14-18B,lemminkäinengatan 14-18 B
20500 Turku / Abo
ALSTOM POWER UK LTD.
United Kingdom
Address
Lichfield Road
ST17 4LN Stafford
Foster Wheeler Energia Oy
Finland
Address

78201 Varkaus
SYDKRAFT AB
Sweden
Address
1,Carl Gustavs Vaeg 1
205 09 Malmoe