Screw Pyrolysis of Sewage Sludge:

Transcription

1 Screw Pyrolysis of Sewage Sludge: A Techno-economic Analysis Marco Tomasi Morgano, Hans Leibold, Frank Richter, Helmut Seifert, Dieter Stapf Symposium on Thermal and Catalytic Sciences for Biofuels and Biobased Products November 1 4, 2016 The Friday Center, University of North Carolina, Chapel Hill 1 KIT The Research University Marco in Tomasi the Helmholtz Morgano Association

2 Sewage sludge production [10 3 ton DS/year] Specific sewage sludge production [kg/p.e./year] Sewage sludge production EU vs. USA Sewage Sludge Production Specific Sewage Slude Production EU Data from A. Kelessidis, A.S. Stasinakis / Waste Management 32 (2012) USA Data from (production of Biosolids 2004) and US Census Bureau (US population 2004) Marco Tomasi Morgano

3 Sewage sludge utilization EU vs. USA EU-27 USA EU Data from A. Kelessidis, A.S. Stasinakis / Waste Management 32 (2012) USA Data from King County / Biosolids Plan Appendix B (June 2012) Marco Tomasi Morgano

4 Motivation New German Sewage Sludge Regulation 2025 (AbfklärV). Recovery of phosphorus in bioavailable form will be mandatory. More stringent toxicological limits will be given. Agricultural use will be forbidden Marco Tomasi Morgano

5 Renquishausen Herdwangen Hayingen Bodnegg Kandern-hammerstein Kreßberg Iffezheim Waldenburg Unterscheidheim Frankenhardt Leintal-Göggingen Blaufelden Burgriden Bernstadt Rudersberg Wilhemsdorf Waibstadt Renningen Niederkrüchten Sigmaringen Sulz/Vöhringen Eggenstein-Leopoldshafen Ellwagen Stockach Steinen Albstadt Lauterstein-Albhof Schönaich Weil am Rhein Leutkirch Balingen Neckarsulm Tübingen Göppingen Rastatt Backnag Mainz-Mombach Bräunlingen Freiburg-Forchheim Karlsruhe Mannheim Stuttgart-Mühlhausen Capacity [ton(ds) /y] Waste Water Treatment Plants in Baden-Württemberg ton (DS)/y 0 data from Umweltbundesamt (2013) / Sewage sludge management in Germany Marco Tomasi Morgano

6 Approach Feedstock characterization and experimental investigations at bench-scale for products distribution and properties. Thermodynamic design of the pyrolysis-based process. Modelling and Scale-up of the reactor. Cost estimation of major components. Evaluation of selected scenarios and determination of Break-even price of char Marco Tomasi Morgano

7 Pre-dried sewage sludge characterization Ultimate analysis wt.% (d.b.) Halogens wt.% (d.b.) C H N S Cl F Proximate analysis wt.% (a.r.) ing value (MJ/kg) (a.r.) Moisture Ash (550 C) Volatile Matter Fixed Carbon HHV LHV Ash composition wt.% of ash SiO 2 Al 2 O 3 CaO MgO P 2 O 5 Na 2 O K 2 O SO Metals concentration mg/kg (d.b.) This Study Sewage Sludge* Soil* Antimony Sb Arsenic As Lead Pb Cadmium Cd Chromium Cr Cobalt Co Copper Cu Manganese Mn Nickel Ni Mercury Hg Thallium Th < Zinc Zn not measured Vanadium V *data from Umweltbundesamt (2013) / Sewage sludge management in Germany Marco Tomasi Morgano d.b. is dry basis a.r. is as received

8 Bench-scale reactor STYX Ceramic Filter Filter elements Vapors + Gas Feedstock Screw Char samples Electrically ed Trough Pyrolysis char Reactor Data Flow Rate < 10 Kg/h Temperature < 600 C Residence Time Min ed Length 2000 mm Screw Diameter 150 mm Filtration Data N Elements 2 14 Length 200 mm Diameter 60 mm Material SiC Online Recleaning Operation Data Time ( ) Material ( ) Main Feedstocks: 3000 h 7,5 tons Wood, Wheat Straw, Sewage Sludge, Chicken Manure, Litter, Oil Sand, etc Marco Tomasi Morgano

9 STYX reactor Marco Tomasi Morgano

10 Sewage sludge pyrolysis Char/solid is always the main product. Minerals retained in the char. Chars contain some volatiles. Mass yields on feedstock basis. Ash Water phase is ammonia solution. Heterogeneous aromatics in the oil. Sulfur in the gas-phase as H 2 S. Energy distribution on LHV basis. LHV CHAR < 10 MJ/kg. LHV OIL > 28 MJ/kg. Chemical energy products > 90%. Process requirements = 450 kj/kg FEED Marco Tomasi Morgano

11 Configuration 1 combustion of vapors Vapors at pyrolysis temperature are incinerated. Hot flue gases are used to heat the pyrolysis reactor. Four sub-configurations: Only : after the reactor, hot water is produced. Only : after the reactor, electricity is produced in motor (Organic Rankine Cycle). EF-MGT+: electricity (Externally Fired Micro Gas Turbine) and hot water (). EF-MGT+: electricity (EF-MGT) and electricity (). Feedstock Pyrolysis vapors Local heat heat exchanger Local heat N 2 Flue gases Air HT- exchanger Combustion air External combustion chamber Pyrolysis reactor Char G Micro gas turbine Recuperator Configuration 1C: EF-MGT Marco Tomasi Morgano

12 Configuration 2 condensation of vapors Pyrolysis vapors are condensed, separated and stored before utilization. Permanent gases and water-like phase are injected in the combustion chamber for the heating of the pyrolysis reactor. Part of the pyrolysis oil is combusted to achieve the capacity of the pyrolysis reactor. Pyrolysis oil is used in the Oil-MGT (Oil - Micro Gas Turbine). Two sub-configurations: Oil-MGT+: electricity (-MGT) and hot water (). Oil-MGT+: electricity (Oil-MGT) and electricity (). Sewage sludge N2 Pyrolysis vapors Condensation unit Permanent gases & water-phase external combustion Flue gases external combustion chamber Combustion air G - Process Pyrolysis reactor Mixer Char Oil Oil tank G μ-gt flue gases Air Recuperator Micro Gas Turbine Oil-MTG Burner Configuration 2B: Marco Tomasi Morgano

13 Thermodynamic balance Thermal input of 500 kw T. Mass flow of pre-dried (10 wt.-% H 2 O) sewage sludge of 173 kg/h. Plant Configuration (450 C) Only Only EF-MGT + EF-MGT + Char [kg/h] 95,3 95,3 95,3 95,3 95,3 95,3 Electric Power [kw] - 49,7 50,9 84,8 47,9 70,7 Local [kw] 152,7-107,4-76,5 - Electric Efficiency [%] - 9,9 10,2 17,0 9,6 14,1 Thermal Efficiency [%] 30,5-21,5-15,3 - CHP Efficiency [%] 30,5 9,9 31,7 17,0 24,9 14,1 Plant Configuration (500 C) Only Only EF-MGT + EF-MGT + Char [kg/h] 92,4 92,4 92,4 92,4 92,4 92,4 Electric Power [kw] - 62,2 54,6 99,8 59,5 88,7 Local [kw] 190,9-143,7-95,9 - Electric Efficiency [%] - 12,4 10,9 20,0 11,9 17,7 Thermal Efficiency [%] 38,2-28,7-19,2 - CHP Efficiency [%] 38,1 12,4 39,6 20,0 31,1 17, Marco Tomasi Morgano

14 Temperature [ C] Temperature [ C] Reactor scale-up STYX bench-scale 500 kw Scaled-up Solids Temperature External Temperature Solids Temperature External Temperature Reactor length [m] Reactor length [m] Mass flow 4 kg/h Mass flow 173 kg/h Residence time 10 minutes Residence time 20 minutes ing Isothermal electric ing Co-current gas Requirements 1 kw Requirements Ca. 45 kw Length 2 m Length 5 m Diameter 0.15 m Diameter 0.50 m Marco Tomasi Morgano

15 Techno-Economic framework (Germany) Cost estimation of the main equipment based on capacity factors. Feedstock costs 90% DM = 40 (dewatering, drying and preparation). Operation cost = 5% of capital costs. Investment costs with Plant factor 2. Price of heat based on natural gas price. Three scenarios for electricity price. Basis: price at the Leipzig European Energy Exchange. Feed-In EEG: price for electricity from renewable energy. Internal Utilization: price for internal production and utilization of electricity. Determination of a break-even price for the char and comparison with potential markets. Gas cleaning equipment not yet considered Marco Tomasi Morgano

16 Investment costs [ ] Investment costs Pyrolysis reactor (1/3 to 1/2 of total investment). EF-MGT includes high temperature heat exchanger (1000 C). External combustion chamber more expensive in configuration with vapors. 500, , , , , , , , ,000 50,000 0 Only Only EF-MGT + EF-MGT + Pyrolysis Reactor Combustion Chamber Condensation Unit Tank Local - Exchanger Oil-MGT EF-MGT Investment costs for nominal pyrolysis temperature 450 C Marco Tomasi Morgano

17 Costs / Revenues [ /y] Costs & Revenues Feedstock costs (dewatering, thermal drying, preparation, etc.) 1/4 to 1/3 of total costs. more valuable than electricity power is a cheap product. None of the configurations survives selling heat and electricity. 250, , , ,000 50, , ,000 Only Only EF-MGT + EF-MGT + Cost and Revenues for nominal pyrolysis temperature 450 C. Feestock costs Annuity Operation costs Local heat Electricity Marco Tomasi Morgano

18 Char break-even price [ /ton] Char break-even price Only needs the lowest price. Larger heat & power plants higher char price. Power is expensive to produce C 400 C 450 C 500 C H 2 S Adsorbents 150 Struvite 100 Ash Landfilling 50 0 Only Only EF-MGT + EF-MGT + Char break-even prices for the six pyrolysis-based plants Marco Tomasi Morgano

19 Char break-even price [ /ton] Alternative scenarios Only still convenient in scenario Feed-In EEG. Combined heat & power better than full electric in scenario internal utilization. Char price reduced by a factor 2 in configuration EF-MGT Only Only EF-MGT + EF-MGT + Char break-even price in alternative scenarios for nominal pyrolysis temperature 450 C. Basis Feed-In EEG Int. Utilization Marco Tomasi Morgano

20 Conclusions & Outlook Products yields and properties on experimental basis at bench-scale. Sewage sludge NOT suitable for direct agricultural use (heavy metals). Two basic set-up with and without condensation of pyrolysis vapors for electric efficiency up to 20% on LHV FEED basis (EF-MGT + ). Reactor scale-up based on experimental validation of numerical model. Pyrolysis reactor most important investment. None of the configuration is rentable without char valorization. production lower char «break-even» price (H 2 S adsorbents). Internal utilization of heat and power most favorable scenario Marco Tomasi Morgano

21 Thank You for Your attention Contact: Marco Tomasi Morgano Phone: Karlsruhe Institute of Technology (KIT) Institute for Technical Chemistry Dept. Pyrolysis / Gas Cleaning Hermann-von-Helmholtz-Platz Eggenstein-Leopoldshafen (D) Marco Tomasi Morgano