University of Pennsylvania ScholarlyCommons Department of Chemical & Biomolecular Senior Design Reports (CBE) Engineering 4-20-2018 Chemical Recycling of Polystyrene Using Pyrolysis Jade H. Bassil University of Pennsylvania, [email protected] Gabrielle Dreux University of Pennsylvania, [email protected] Gwendolyn A. Eastaugh University of Pennsylvania, [email protected] Follow this and additional works at: https://repository.upenn.edu/cbe_sdr Part of the Biochemical and Biomolecular Engineering Commons Bassil, Jade H.; Dreux, Gabrielle; and Eastaugh, Gwendolyn A., "Chemical Recycling of Polystyrene Using Pyrolysis" (2018). Senior Design Reports (CBE). 103. https://repository.upenn.edu/cbe_sdr/103 This paper is posted at ScholarlyCommons. https://repository.upenn.edu/cbe_sdr/103 For more information, please contact [email protected]. Chemical Recycling of Polystyrene Using Pyrolysis Abstract There are significant economic and environmental benefits ot the recycling of waste plastics, especially that of polystyrene. Currently, much of polystyrene waste is sent to landfills due ot the difficulty in separation and cleaning processes, where it accumulates indefinitely. It contributes to plastic pollution and adversely affects wildlife, oceans and humans. Pyrolysis of waste polystyrene is explored in this paper as a chemical recycling method. This reaction yields useful liquid fuel products such as styrene, ethylbenzene, toluene, and methylstyrene, which can be sold to provide project revenues. Beginning with a polystyrene feed of 100 tons per day, the suggested design achieves a liquid styrene product purity of 99.9%. The plant includes a rotary- kiln reactor to carry out the pyrolysis reaction and a distillation train to isolate the liquid products. Pumps, blowers and storage equipment are also included in the design. Heat and energy are optimally integrated using heat exchangers to reduce the cost of purchased utilities. The suggested design requires a capital investment of $25.0 MM and yields a fifteen-year net present value of $5.1 MM. The internal rate of return it achieves is equal to 18.5%. The projected cash flows of this plant suggest that it will break even by 2030 on a cumulative discounted free cash flow basis. The design is recommended based on project specifications and current price projections, though investors should exercise caution with regards to the effect of realistic market prices of styrene and polystyrene on the project’s profitability measures. Disciplines Biochemical and Biomolecular Engineering | Chemical Engineering | Engineering This working paper is available at ScholarlyCommons: https://repository.upenn.edu/cbe_sdr/103 University of Pennsylvania, School of Engineering and Applied Science Department of Chemical and Biomolecular Engineering 220 South 33rd Street Philadelphia, PA 19104 April 17, 2018 Dear Dr. Daeyeon Lee and Mr. Bruce Vrana, Enclosed is a proposal for the design of a waste plastics pyrolysis process based on the research of A. Karaduman. The proposed plant uses pyrolysis to recycle polystyrene and produce its monomer styrene as the main product. The process design is based on a feedstock of 100 tons per day, with the goal of producing styrene monomer at a polymer grade purity greater than 99.9%. The plant is to be located in an industrial complex on the United States Gulf Coast where a number of styrene monomer producers are situated. Clean and sorted polystyrene is collected, densified, and brought to the facility, where the feedstock will have ample space for storage due to the large capacity required. It is then fed to a rotary kiln reactor to carry out the pyrolysis reaction. The rotating vessel attached to an auger allows for the solid residue removal. The gaseous product is cooled to produce high-pressured steam, then condensed to separate the light hydrocarbons from the desirable liquid products. The light gases are reused as fuel gas for pyrolyzer heating and any excess is sold. The liquid product mixture is separated using distillation columns to isolate styrene and other liquid products (ethylbenzene, methyl styrene and toluene) at purity levels higher than 99.9%. Seven days’ supply of products is maintained in storage tanks. Energy and heat integration is optimized to reduce operating expenses. The plant will operate for 24 hours a day, 330 days a year, with polystyrene available for $0.30 per pound and styrene valued at $1.00 per pound. The proposed design requires an investment of $25.0 MM to meet the processing goal of 100 tons per day of polystyrene, and yields an investor’s rate of return (IRR) of 18.5%. We recommend investing in this process while remaining wary of the market prices of polystyrene and styrene. Sincerely, ___________________ ___________________ ___________________ Jade Bassil Gabrielle Dreux Gwendolyn Eastaugh Recycling of Polystyrene Using Pyrolysis 2 Recycling of Polystyrene Using Pyrolysis Chemical Recycling of Polystyrene Using Pyrolysis Jade Bassil | Gabrielle Dreux | Gwendolyn Eastaugh Project submitted to Dr. Daeyeon Lee and Prof. Bruce Vrana. Project proposed by Matthew Targett. Department of Chemical and Biomolecular Engineering School of Engineering and Applied Science University of Pennsylvania April 18, 2017 3 Recycling of Polystyrene Using Pyrolysis Table of Contents Section 1. Abstract 7 Section 2. Introduction and Objective-Time Chart 8 i. Introduction 8 ii. Objective-Time Chart 10 Section 3. Innovation Map 11 Section 4. Market and Competitive Assessment 12 Section 5. Customer Requirements 14 Section 6. CTQ Variables – Product Requirements 14 Section 7. Product Concepts 14 Section 8. Superior Product Concepts 14 Section 9. Competitive (Patent) Analysis 14 Section 10. Preliminary Process Synthesis 15 i. Polystyrene Assumptions 15 ii. Alternative Recycling Methods 17 iii. Type of Pyrolyzer 18 iv. Determination of Products 19 v. Utilization of Fuel Gas 20 vi. Separation Process 21 Section 11. Assembly of Database 23 Section 12. PFD and Material Balances 25 Section 13. Process Descriptions 30 i. Process Overview 30 ii. Section 000-Feed 30 iii. Section 100-Core Pyrolysis Process 31 iv. Section 200-Separation 33 Section 14. Energy Balance and Utility Requirements 36 i. Energy Integration Method 36 ii. Heat Integration Method 37 iii. Utilities 38 Section 15. Equipment List and Unit Descriptions 40 i. Reactor Vessel 40 4 Recycling of Polystyrene Using Pyrolysis ii. Pumps and Blower 41 iii. Heat exchangers 46 iv. Distillation Columns 48 v. Storage Tanks 52 Section 16. Specification Sheets 54 Section 17. Equipment Cost Summary 68 Section 18. Fixed Capital Investment Summary 71 Section 19. Operating Cost – Cost Of Manufacture 73 i. Variable costs 73 ii. Fixed costs 74 Section 20. Profitability Analysis 76 i. Profitability Measures 76 a. Fixed and Variable Costs 81 b. Sales 85 c. Capital costs 88 Section 21. Other Important Considerations 91 i. Safety and Health Considerations 91 ii. Environmental Impact 91 Section 22. Conclusions and Recommendations 93 Section 23. Acknowledgments 94 Section 24. Bibliography 95 Section 25. Appendix 97 A. Calculations 97 a) Bucket Elevators 97 b) Silos 97 c) Screw Feeders 97 d) Kiln 98 e) Blower 98 f) Heat Exchangers 99 g) Pumps 100 h) Electric Motors 100 i) Storage Tanks 101 j) Distillation Columns 101 B. Tables and Figures 103 5 Recycling of Polystyrene Using Pyrolysis C. MSDS Sheets 105 D. Aspen Report 110 a) Block Report 110 b) Streams Report 180 6 Recycling of Polystyrene Using Pyrolysis Section 1. Abstract There are significant economic and environmental benefits to the recycling of waste plastics, especially that of polystyrene. Currently, much of polystyrene waste is sent to landfills due to the difficulty in separation and cleaning processes, where it accumulates indefinitely. It contributes to plastic pollution and adversely affects wildlife, oceans and humans. Pyrolysis of waste polystyrene is explored in this paper as a chemical recycling method. This reaction yields useful liquid fuel products such as styrene, ethylbenzene, toluene, and methylstyrene, which can be sold to provide project revenues. Beginning with a polystyrene feed of 100 tons per day, the suggested design achieves a liquid styrene product purity of 99.9%. The plant includes a rotary- kiln reactor to carry out the pyrolysis reaction and a distillation train to isolate the liquid products. Pumps, blowers and storage equipment are also included in the design. Heat and energy are optimally integrated using heat exchangers to reduce the cost of purchased utilities. The suggested design requires a capital investment of $25.0 MM and yields a fifteen-year net present value of $5.1 MM. The internal rate of return it achieves is equal to 18.5%. The projected cash flows of this plant suggest that it will break even by 2030 on a cumulative discounted free cash flow basis. The design is recommended based on project specifications and current price projections, though investors should exercise caution with regards to the effect of realistic market prices of styrene and polystyrene on the project’s profitability measures. 7 Recycling of Polystyrene Using Pyrolysis Section 2. Introduction and Objective-Time Chart i. Introduction The growing use of plastics in modern society has created significant sustainability concerns. Plastics, although valuable for their inherent strength and durability, pose complications regarding their disposal as are non-degradable and thus accumulate in the environment indefinitely. Only ten percent