Mixed Plastics Recycling Plant - Reck 'em Recyclers
thesisposted on 08.05.2020, 00:00 authored by Nunzio Giorgio Carducci, Anders Hoglund, Maxon Lube, Damiana Murdock
Mismanaged plastic waste is a serious problem, and the United States is responsible for 13% of the annual global plastic waste production. Less than 10% of the plastic used in the United States is recycled, and traditional mechanical recycling methods can only be used six times before the plastic is no longer usable. Chemical recycling technologies can help solve these issues. The goal of the following project is to design a plant that can process all seven plastic types using chemical recycling technologies and be economically feasible. While this plant cannot recycle all seven consumer plastic types, it is able to accept and sort a mixed input stream of those plastics with the objective of promoting a more circular plastic cycle. Supercritical methanolysis will be used to recycle polyethylene terephthalate (PET) into the virgin monomers dimethyl terephthalate (DMT) and ethylene glycol (EG), and pyrolysis will recycle polyethylene (PE), polypropylene (PP), and polystyrene (PS) into fuel oils. Polyvinyl chloride (PVC) will be sorted and sold to prevent the release of chlorinated compounds through pyrolysis. The expected processing rate is 18,500 tons of mixed plastics and an additional 16,415 tons of pre-sorted PET per year. Pyrolysis will process 36.6 tons per day of mixed PE, PP, PS, and other plastics using two fluid catalytic cracking reactors with a processing capacity of 20 tons per day each. Condensers and filtration will yield pyrolysis oil that is composed of 35% motor gasoline, 45% diesel, and 20% No. 6 fuel oil (used in industrial boilers). Byproducts such as syn gas and light fraction residuals will be combusted to help heat the reactors, whereas carbon black will be sold separately. According to RTI International, the emissions produced from the reactor are insignificant requiring no emissions control system. Methanolysis will process the 3.3 daily tons of PET from the sorting line and 49 tons of outsourced PET that has already been presorted. Daily DMT production is expected at 52.7 tons at 99% purity. Daily ethylene glycol output is expected to be 16.6 tons. These numbers are estimated based on an input of 52 tons of PET and 312 tons of methanol. Economic analysis assumed a 21% tax rate and 20-year lifespan with MACRS5 depreciation schedule. MARR was set at 20% since the recycling market is well-established, but this plant combines new, medium-risk sorting techniques and chemical recycling processes. Equipment for methanolysis and pyrolysis were based on data from Peters et al. Delivered equipment cost is expected to be $7.1 million using a delivery rate of 10% of the purchased equipment cost. Fixed capital investment totaled $28.2 million, and the total capital investment was $41.7 million. Operational costs were found to be $16.7 million, and methanolysis electricity costs alone contribute nearly $7 million to that figure. Annual revenue was estimated to be $28.9 million. A cash flow analysis resulted in a payback period of 9 years, an IRR of 10%, and net present value (NPV) of –$35.1 million at a 20% interest rate. NPV0 was calculated to be +$131.7 million. Since the IRR does not exceed the MARR of 20%, this project cannot be recommended on an economic basis. However, considerations should be made when viewing the plant from a sustainability standpoint. An important note is that a gate or tipping fee was not considered in the cash flow analysis. Preliminary analysis of additional revenue from a gate fee and/or government subsidy show an additional $9.09 million per year ($491.37/ton) is needed to achieve an NPV of 0 at 20% interest. A gate fee of $70/ton, which is comparable to the landfilling fee in the New York area, would result in an IRR of 12% and NPV20 of –$30.1 million. The price of electricity presents considerable economic risk because of how much is used, mainly in the methanolysis process. Electricity accounts for nearly half of the annual $15.8 million in variable production costs. Fluctuations of even $0.01/kWh can change the annual cost by $1 million. The sale price of DMT also poses significant economic risk if the price were to drop. About $17.7 million of the $28.9 million in annual revenue comes from DMT alone. Market fluctuation in the selling price can greatly affect the overall revenue. To conclude, the project is not economically viable with an IRR of 10%. Government subsidies and a gate fee should be considered to improve the IRR, and a competitive gate fee of $70/ton raises the IRR to 12%, based on preliminary results. To meet a target IRR of 20%, an additional $9.09 million must be raised annually. Further studies should be made on the impact that utilities and market values have on the project economics due to electricity expenditures and the sale price of DMT being critical components to the profitability of the project. Further research should be conducted on how to effectively separate out dyes from the methanolysis products and determine if the additional expenditures are outweighed by the marginal increase in revenue by selling cleaner DMT and EG. CreaSolv looks to be a promising route if enough PET can be sourced to recycle and offset the additional capital costs. Expansion of the methanolysis process should also be considered as it can be very profitable if more PET can be processed.