Rotary kiln pyrolysis- First results of a 3 MW pilot plant

Transcription

1 Rotary kiln pyrolysis- First results of a 3 MW pilot plant 4th International Freiberg Conference on IGCC & XtL Technologies 3-5 May 2010 Dresden, Germany

2 Overview About the project Balance of the pyrolysis pilot plant Results Outlook 2

3 About the Project Usage of agricultural residues (straw) for power generation is a widely unexplored source of energy Cheap feedstock regional available in huge amounts Fundamental idea: Co-firing of straw in an existing coal fired power station Problem: high content of Chlorine (Cl) and Potassium (K) of the straw is harmful for boiler and heat exchanger of the power station 3

4 About the Project Troubleshooting: Split up of the biomass into a volatile fraction that can be used for co-firing and a char fraction by a pyrolysis process. The undesired components (Cl, K, Na) should be concentrated in the char fraction. Pyrolysis-pilot plant Dürnrohr Jacked rotary kiln reactor (3 MW th ) 4

5 Kohlekraftwerk Dürnrohr Austria s biggest coal fired power plant built as a replacement for the Zwentendorf nuclear power station, a plant that was finished but due to a 1978 referendum never started up consists of two blocks electrical output of 405 MW (operated by Verbund Austrian Thermal Power AG) and electrical output of 352 MW operated by the Energie- Versorgung Niederösterreich (EVN) AG The plant is powered by black coal imported from the Czech Republic and Poland but it can also use natural gas as a fuel In 2004 a heating plant (largest such in Austria, at the time) using the dissipated waste heat was opened 6

6 About the project 7

7 Flowsheet 8

8 Operating figures Fuel power of the rotary kiln reactor: 3 MW Throughput of straw: ca. 600 to 800 kg/h Pyrolysis temperature range: C Residence time of the feedstock: min Pyrolysis gas characteristics Content of pyrolysis oil (gravimetric): g/nm³ Content of pyrolysis oil (GC-MS): g/nm³ Dust and entrained char: mg/nm³ 9

9 Feedstock Wheat straw (indoor stored) Wheat straw (field stored) Maize straw Straw pellets Sorghum straw Reed straw Palm nut shells Miscanthus straw Actiprot 10

10 11 Fuel Samples Reed Straw Straw Pellets Palmnut Shells Miscanthus Straw Wheat Straw Sorghum Straw

11 Pyrolysis Char Samples Reed Straw Palmnut Shells Miscanthus Straw Straw Pellets Wheat Straw Sorghum Straw 12

12 Balance of the plant Creating a model of the system Process simulation tool IPSEpro (stationary equation oriented flow sheet simulation) Validation of measured data C-Programming IDE Fig.: Structure of IPSEpro (SimTech, 2001) Property Libraries (DLLs) 13

13 Part of the testing scheme Straw Variation of the pyrolysis temperature Variation of the residence time Actiprot Variation of the pyrolysis temperature 15

14 Straw mass fraction [%] char pyrolysis oil pyrolysis gas energy fraction [%] char pyrolysis oil pyrolysis gas pyrolysis temperature [ C] pyrolysis temperature [ C] Fig.: Mass- and energy fractions of the pyrolysis products of straw controlled by the pyrolysis temperature 16

15 Actiprot char char mass fraction [%] pyrolysis oil enrgy fraction [%] pyrolysis oil pyrolysis gas pyrolysis gas pyrolysis temperature [ C] pyrolysis temperature [ C] Fig.: Mass- and energy fractions of the pyrolysis products of Actiprot controlled by the pyrolysis temperature 17

16 Separation of the chemical elements 100% 90% Separation in char, gas and oil 80% 70% 60% 50% 40% 30% 20% 10% pyrolysis oil pyrolysis gas char 0% C H O N S Cl K Elements Fig.: Separation of the chemical elements in pyrolysis gas, pyrolysis oil and char for a pyrolysis operation of indoor stored straw. 18

17 Efficiency Chemical efficiency 1.0 chemical efficiency [1] pyrolysis temperature [ C] straw acti prot 19

18 Efficiency Efficiency Pyrolysis process 0.48 Coal fired power station Dürnrohr Generated electricity by straw Sankey-diagram for straw pyrolysis for the case of energy supply by pyrolysis gas, energy flows [kw] 20

19 Conclusions The process works technically correct The gaseous product is suitable for co-firing in a coal fired power plant The undesired components (Cl, K) are concentrated in the char fraction Efficiency is significantly higher than the electrical efficiency of smaller biomass fired power stations or CHP systems. Approximately 50 % of the energy in the feedstock can be provided for co-firing Further investigations on usage of biochar More Fuels (e.g. sewage sludge, residues from agricultural and paper industry) 21

20 Outlook Connection of the pyrolysis process to the coal fired power plant. Scenario 1: 1 x 30 MW (one rotary kiln reactor) Scenario 2: 3 x 30 MW (three rotary kiln reactors) Fig.: Scenario 1 22

21 End 23