Fine particle and flue gas measurement services. Juho Kauppinen Jyväskylä, 24th September 2014 VTT Technical Research Centre of Finland

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1 Fine particle and flue gas measurement services Juho Kauppinen Jyväskylä, 24th September 2014 VTT Technical Research Centre of Finland

2 2 Combustion services at power plants Fouling and corrosion monitoring services for multifuel boilers Fine particle and flue gas measurements and analyses Ash utilisation studies

3 3 Challenges in power production from biomass/waste The spectrum of fuels used in energy production has become more and more diverse and at the same time, higher and higher steam values are targeted The introduction of agro biomasses and waste fuels have brought a great deal of challenges such as corrosion and fouling Part of the problems are still unsolved due to complexity of ash chemistry and corrosion processes In order to cope with the challenges, the chemical environment inside the boiler need to be known more accurately For this purpose VTT offers advanced fine particle and gas measurements

4 4 Why to measure fine particles? Most of the operational problems such as fouling and corrosion of the heat transfer surfaces are caused by the compounds that vapourize in the furnace and later form PM1 (<1 m) particles - KCl, NaCl, ZnCl 2, PbCl 2, KBr, NaBr Thus, knowing the amount and composition of PM1 particles at different locations is extremely important for understanding the origin of the problems and for finding the possible remedies - The key for useful results is the size classification of the particles; analysis of the bulk ash does not suffice Corrosive alkali or heavy metal salts Biomass/waste Coal Coal+Biomass/waste

5 5 Fine particle and flue gas measurement equipment (1/2) The fine particle measuring system developed by VTT consists of: - A sampling system (probe, dilution stages, heated lines, separators etc.) - Two parallel Dekati low pressure mass impactors (DLPI) - Electrical low pressure impactor (ELPI) - Two Fourier transformation infrared gas analysers (FTIR) + O 2 analysers In addition, Micro Gas Chromatograph ( GC) and Total Reduced Sulphur (TRS) analyser can be used to extend the spectrum of gaseous compounds that can be determined

6 6 Fine particle and flue gas measurement equipment (2/2)

7 7 Measuring procedure (1/2) Flue gas sample is taken from the furnace/flue gas channel and it is quickly cooled down in a permeable tube diluter, where compounds that exist as vapors form aerosol particles Sample is then led via further dilution stages and particle pre-separators into the impactors, where particles are classified into 13 fractions (0-10 m) according to their (aerodynamic) size Mass impactors collect samples that are weighed to obtain mass-size distributions after which samples are sent to chemical analysis (ICP-MS, IC) - Compounds soluble in water and in acid can be determined separately as two parallel samples are obtained Information on the compounds elements exist in Source: Dekati Ltd Corrosive alkali or heavy metal salts

8 8 Measuring procedure (2/2) ELPI is used to continuously monitor the particle number size distribution - Online data showing for example the effect of changes in fuel mix, additives, process parameters optimization of DLPI sampling Source: Dekati Ltd FTIRs is used to obtain the dilution ratio and to analyse the gas composition - CO 2, CO, H 2 O, NO, N 2 O, NO 2, SO 2, HCl, HF, NH 3, CH 4, etc. With complementing analysers O 2, N 2, H 2, H 2 S and other reduced sulphur compounds, among others, can be measured

9 9 Advantages (1/2) The root cause for the problems is measured directly and quantitatively as opposed to typical deposition or mass loss corrosion probe measurements - These measurements complement each other: chemical environment is characterized when composition of the deposit together with gas/vapor and particulate phases and are known Process changes are seen quickly in fine particles and gases Online data on the amount of corrosive compounds in the flue gas is obtained optimization of test points Not limited to certain corrosive compounds (NaCl, KCl) like the current optical measurements; also compounds do not need to be in vapour form anymore at the sampling location

10 10 Advantages (2/2) It is possible to obtain vertical and/or horizontal particle and gas profiles to - Better understand why corrosion takes place at certain locations - Investigate flue gas mixing/channeling - Study the needed residence times and optimal temperature windows for additives Vapour/fine particle compositions are extremely useful data for modelling purposes - For example validating thermodynamic equilibrium models used for predicting the corrosiveness of the flue gases

11 11 Method development and experience Measuring fine particles and analysing their composition is challenging and requires special knowledge and equipment - Especially the proper flue gas sampling techniques are crucial in order to avoid losses and unwanted chemical reactions - Small mass of the particle samples also pose a challenge for their reliable chemical analysis During the last ten years, methods have been developed at VTT in cooperation of Metso Power to mitigate these challenges and great amount of knowledge has been gained on the behaviour of fine particles in different processes Now we can offer reliable fine particle and flue gas measurements and expertise on interpretation and utilisation of the results

12 12 What has been studied? Combined to other measurements, fine particle measurements have been utilised for determining for example: - Safe share of risky fuel in co-firing - The optimal use of additives for corrosion mitigation What is the best additive and needed dosage Needed residence time Optimal temperature window and injection location - The effect of an empty pass and process parameters on corrosivity of flue gases - Waterwall corrosion mechanisms - Behaviour of trace elements Measurements have been carried out in grate, BFB, CFB, PF and recovery boilers and from lab-scale to full-scale - Suitable also for gasifiers etc.

13 13 Summary Agro and waste fuels have brought major challenges such as extreme fouling and corrosion of the heat transfer surfaces Due to great complexity of ash chemistry of these new fuels, traditional measurements alone do not anymore suffice when the phenomena inside the boiler need to be understood With VTT s advanced fine particle measurements and analysis, a lot of new crucial information on the process can be obtained for finding the optimal solutions

14 14 List of publications (1/2) P. Vainikka, D. Lindberg, A. Moilanen, H. Ollila, M. Tiainen, J. Silvennoinen, M. Hupa, Trace elements found in the fuel and in-furnace fine particles collected from 80MW BFB combusting solid recovered fuel, Fuel Processing Technology, Volume 105, 2013, pp J. Silvennoinen, M. Hedman, Co-firing of agricultural fuels in a full-scale fluidized bed boiler, Fuel Processing Technology, Volume 105, 2013, pp M. Aho, K. Paakkinen, R. Taipale, Quality of deposits during grate combustion of corn stover and wood chip blends, Fuel, Volume 104, 2013, pp M. Aho, K. Paakkinen, R. Taipale, Destruction of alkali chlorides using sulphur and ferric sulphate during grate combustion of corn stover and wood chip blends, Fuel, Volume 103, 2013, pp M. Hedman, J. Maunula, J. Roppo, T. Sorvajärvi, J. Toivonen, P. Vainikka, Measurement and control of the corrosivity of the environment in combustion of solid recovered fuels in BFB boiler, Impacts of Fuel Quality on Power Production and the Environment, Puchberg, Austria, September 23-27th, J. Silvennoinen, M. Hedman, Combustion of agricultural fuels in a full-scale fluidised bed boiler, Impacts of Fuel Quality on Power Production and the Environment, Puchberg, Austria, September 23-27, 2012.

15 15 List of publications (2/2) P. Vainikka, S. Enestam, J. Silvennoinen, R. Taipale, P. Yrjas, A. Frantsi, J. Hannula, M. Hupa, Bromine as an ash forming element in a fluidised bed boiler combusting solid recovered fuel, Fuel, Volume 90, Issue 3, 2011, pp P. Vainikka, J. Silvennoinen, P. Yrjas, A. Frantsi, L. Hietanen, M. Hupa, R. Taipale, Bromine and Chlorine in Aerosols and Fly Ash when Co-Firing Solid Recovered Fuel, Spruce Bark and Paper Mill Sludge in a 80MWth BFB Boiler, Proceedings of the 20th International Conference on Fluidized Bed Combustion 2010, pp M. Aho, P. Yrjas, R. Taipale, M. Hupa, J. Silvennoinen, Reduction of superheater corrosion by co-firing risky biomass with sewage sludge, Fuel, Volume 89, Issue 9, 2010, pp M. Aho, A. Gil, R. Taipale, P. Vainikka, H. Vesala, A pilot-scale fireside deposit study of co-firing Cynara with two coals in a fluidised bed, Fuel, Volume 87, Issue 1, 2008, pp M. Aho, P. Vainikka, R. Taipale, P. Yrjas, Effective new chemicals to prevent corrosion due to chlorine in power plant superheaters, Fuel, Volume 87, Issue 6, 2008, pp

16 16 Contact information Jouni Hämäläinen, Team leader - Jouni.Hamalainen@vtt.fi - Mobile: Martti Aho, Principal Scientist - Martti.Aho@vtt.fi - Mobile: More information on VTTs combustion related services can be found from:

17 17 VTT - 70 years of technology for business and society