Low grade waste plastics to fuel products. Sam Haig Senior Engineer, Axion Consulting March 2014

Transcription

1 Low grade waste plastics to fuel products Sam Haig Senior Engineer, Axion Consulting March 2014

2 Contents About Axion Breakdown of plastic waste Why not incinerate waste plastic? Alternatives to incineration Feedstock considerations Syngas upgrading options Conclusions

3 Axion Group ~40 staff Manchester Shanghai ~40 staff Salford Trafford Park

4 Axion Polymers 200,000t/yr

5 Axion Consulting Develops novel processing and collection routes for resource recovery Wide range of clients in the recycling and process industries Active in recycling technology for ELV, WEEE and domestic & commercial/industrial waste

6 UK plastic packaging use 2013 Non-cons rigids 8% Other 4% PTT 22% Films 41% 2.5 million tonnes 40 kg/person Bottles 25% Valpak plastic packaging update 2013

7 UK plastic packaging use 2013 Non-cons rigids 8% PTT 22% Other 4% High grade Films 41% PET HDPE Bottles 25% Recycling

8 UK plastic packaging use 2013 Non-cons rigids 8% PTT 22% Other 4% Medium grade Films 41% PP PS Bottles 25% Recycling

9 UK plastic packaging use 2013 Non-cons rigids 8% PTT 22% Other 4% Low grade Films 41% PVC PP LL/L/M/HDPE Bottles 25% Landfill Incineration?

10 The argument for incineration Plastic is just solid oil we burn oil for power so plastic incineration is the best option. Or is it? Incineration = Sky-fill + ash generation (+ some energy recovery)

11 Plastic incineration environmental GWP: Long life (fossil) carbon more important than short life Incinerating paper, wood = part of CO 2 cycle Incinerating plastic = net gain in CO 2 cycle Cannot replace power from low-carbon sources

12 Plastic incineration financial Incinerators are commercial operations Large proportion of income from gate fees Heat load fixed high CV is bad Plastic has higher CV than other waste Therefore less waste needed per kw =less gate fee per kw

13 So what are the options? Incineration: no environmental, economic or technical sense Landfilling: burying useful resource Recycling: high operating costs and low yields The alternative? Chemical conversion to oil products

14 Chemical conversion to oil products Pyrolysis Catalytic depolymerisation Gasification to syngas followed by: Fischer-Tropsch synthesis Methanol-to-Gasoline conversion Bioproduction of Ethanol

15 Material compositions by moles 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% C H O Cl

16 Material compositions by mass 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% C H O Cl

17 Pyrolysis & depolymerisation Gas Residue Waste plastic Drying Pyrolysis/ depolymerisation Distillation Plastic heated to: C (pyrolysis) C plus catalyst (depolymerisation) Minimise heating time to increase liquid fraction High recovery rate possible (60-70%) Issues: Low tolerance to contamination Char Produces (unstable) soup of 400+ components Required heat load limits max. unit size to 1 te/hr Liquid hydrocarbons

18 Hydrogen deficiency in pyrolysis/cd Polymer chain breaks at two locations Hydrogen deficiency for all four ends of polymer chain Chain shortened, depositing char Undesirable reactive bonds formed Undesirable cyclic hydrocarbons formed

19 Gasification Partial oxidation of plastic to syngas Simple molecules for further upgrading High temperature (900-1,100 C) Resistant to contamination Water-gas shift to balance CO:H 2 ratio Suitable for large scale

20 Equilibrium gas product

21 Fischer-Tropsch synthesis Clean syngas Steam Compression Water-gas shift Fischer- Tropsch Diesel Steam Syngas directly converted into diesel nco + 2nH 2 (CH 2 )n + nh 2 O + Heat Moderate T ( C) and high P ( bar) Fe/Co/Ni catalyst required Water & purge gas Max yield needs 1:2 CO:H ratio: gasification gives1:0.7 Needs catalytic shift reaction to convert CO into hydrogen and (useless) CO 2

22 Methanol to Gasoline Clean syngas Steam Compression Water-gas shift Methanol reactor MTG reactor Gasoline Steam Water & purge gas 2-step process: syngas MeOH gasoline CO + 3H 2 CH 3 OH (CO 2 + 3H 2 CH 3 OH + H 2 O) 2nCH 3 OH nch 3 OCH 3 + nh 2 O (CH 2 ) 2n + 2nH 2 O Moderate T (250 C) and high P (50 bar) High quality gasoline produced Water & purge gas

23 Bioproduction of Ethanol Water Clean syngas Bioethanol reactor Distillation Ethanol Off-gas Water Ideally uses 1:1 CO:H ratio 6CO + 3H 2 O C 2 H 5 OH + 4CO 2 6H 2 + 2CO 2 C 2 H 5 OH + 3H 2 O Low temperature and pressure More tolerant to sulphur than other processes Low solubility of syngas in water produces low concentration EtOH

24 Summary comparison Product Energy yield Minimum scale CAPEX required Pyrolysis Crude oil 80% Small Low Catalytic depolymerisation Gasification w/ Fischer-Tropsch Gasification w/ MeOH-Gasoline Gasification w/ Bioprocessing Gasoline/ diesel mix Diesel (+ waxes) 75% Small Medium 30% (50%) Large High Gasoline 45% Large High Ethanol 50% Large High

25 Conclusion Low grade waste plastics a feasible feedstock for conversion to oil products Direct incineration not the best option Gasification routes preferable: Greater control and flexibility with products Issues with contamination (O, Cl, S) but some tolerance However If it could be recycled as plastic, even better!

26 Thank you for listening

27 Tudor House Meadway Bramhall Stockport SK7 2DG Tel : Fax: shaig@axionconsulting.co.uk