Research Needs on Pyrolysis and Gasification of Waste Prof. Dr. Christian Ludwig Joint Professorship on Solid Waste Treatment and Valorization Workshop, Brussels, January 2006
Overview status according to BREF on Waste Incineration July 2005 - high temperature processes - emerging techniques new available technologies / facilities - conventional pyrolysis / gasification emerging techniques: P/G ++ - combined processes (heat, power and fuels) - hydrothermal processes (wet or very toxic wastes) challenges: hetero atoms in waste and biomass / trace compounds SWOT and recommendations
BREF on Waste Incineration and Waste Treatment Industries - extensive compilation - does not contain treatment of special wastes, such as batteries where pyrolysis is successfully applied - BAT based on high temperature integrated melting processes have still difficulties entering the market (e.g. RCP-HSR, Thermoselect) - BAT based one high temperature gasification / incineration make improvements but have still difficulties entering the market, especially new technologies for MSW treatment with high quality standards have difficulties (e.g. PECK) - BAT based on pyrolysis and in combination with combustion and mechanical processes are slowly entering the market (e.g. Citron: Oxy-reducer process, Thide process, others). Of advantage is the possibility to treat different sorts of waste.
Thide mill steam, hot water dryer combustion 1200 C pyrolysis 450-700 C carbon metals salts glass http://www.thide.com/thermolyse/avantage/ http://www.thide.com/thermolyse/avantage/
Gasification Trend: Production of Clean Fuels 30 25 syngas solid waste, biomass gasification coal gc/mj 20 15 oil solid fuels air pollution methane (NG) 10 5 0 hydrogen gases clean combustion 1 10 100 1000 10000 100000 1000000 Molecular weight Stucki et al., Laboratory for Energy and Materials Cycles, PSI
Example: wood gasification Heat and Power Güssing (Austria) 8 MW th, 2.0 MW el Idea: production of CH 4 TU Wien, REPOTEC http://www.ficfb.at/ http://www.renet.at/
The central reactions in waste fuel processing Waste Reforming (endothermic) H 2 O CH x O y CO, CO 2, H 2 Power generation SNG Methanation (exothermic) H 2 O CH 4, CO 2 CO, CO 2, H 2
CWT process for treating wastes at hydrothermal conditions step 1: slurrying the organic and inorganic materials with water; step 2: heating the slurry under pressure to reaction temperature; step 3: flashing the slurry to a lower pressure to release the gaseous products after the initial reaction is complete; step 4: reformer reactor segments solids from volatile chemicals; step 5: heating the oil to drive off water and separate light oils from gases; step 6: separation and storage of the light oils and gases. Carthage, Missouri http://www.changingworldtech.com/
Trends of processes - treatment oriented processes (goal of waste management!) - product oriented processes (from waste treatment to production from waste ) materials, toxicity energy all in one incineration before pyrolysis/gasification before melting (costs, complexity of technology: keep it simple! ) combination of pyrolysis / gasfication and other processes e.g. mechanical treatment potential of hydrothermal processes under investigation
Trends of products - heat - power (see incineration) - fuels (gaseous, liquid and solid) - metals - glass (inert materials) - constructions materials development: energy before materials ( greenhouse gas driven) profitable: combined recovery via mechanical processes
Chains of Recovery / Challenge hetero atoms pyrolysis gas solid residue slurry conditioning / cleaning combustion gasification / reforming separation conditioning / cleaning heat / power fuel / chemicals reducing agent / solid fuel metals / inert materials emission control Integrated and / or combined processes / issue of quality
quality especially problematic are hetero-atoms Pyrolysis / gasification technologies are well known: - a major challenge are the waste related trace impurities Changing of waste input is important: - blending for optimal products (disposal or use) - high flexibility means high competitiveness in the market Control of quality is important: - catalysts, fuel cells - high temperature corrosion (e.g. blades of turbines) - emissions
quality Gas cleaning targets of process components a few targets are given by suppliers of certain technologies (e.g. gas turbines, SOFC) targets for product depend on the distributor (e.g. gas grid) but, quality of gases cannot be measured correctly arbitrary assumptions, classifications, and decisions are made this puts future technology development at risk - if wrong targets are set (because of bad scientific-technical knowledge or on purpose to prevent the entrance of a new technology) - if measurements cannot be made accurate (for development or in-line for control purposes) - if models predict wrong elemental flow behavior - if emissions are out of control
quality Problems to be solved / research challenges: - No good tools and models are available for predicting flows of hetero atoms (e.g. S, N, alkali / heavy metals, critical substances) - Flow analysis cannot be investigated and measured accurate enough if input is changing; transient phenomena are especially difficult to investigate for traces (BAT is not good enough) - Assessment (e.g. by LCA) is actually not feasible without this information - Quality of the gases in the process cannot be guaranteed - Distribution of toxic compounds into products and environment is unknown
Example: Alkali-Emissions from biomass 0.5 0.4 pyrolysis of sawdust Pyrolyse von Holzsägemehl Alkali-Signal / na/mg Probenmasse / mg 12 Alkali-Signal / na/mg 0.4 signal from 0.3 alkali 0.3 detector 0.2 0.2 0.1 0.1 signal from thermo gravimeter 10 8 Masse / mg 6 4 2 0.0 0 200 400 600 800 1000 Temperatur / C temp. [ C] 0
SWOT strength combination of thermal and non thermal treatment methods: recovery of metals, CHP recovery efficiency nutrients from waste chemicals from waste fuels from waste opportunities New analytical tools to investigate elem. flows in transient systems of waste-toenergy and waste-to-fuel processes; New tools for the prediction of elemental flows Evaluation of hydrothermal processes from waste treatment to production weakness trace elemental flows not known costs vs. ecological benefit not always clear assessment difficult in case of changing input; how to find out which is the better technology? assessment models using elem. flows threats low social acceptance (anti-incineration) ecological benefit cannot be guaranteed, if the flow of trace materials cannot be controlled the ecologically less sound technology will win; future generations pay