Material Recovery Facilities Process Modeling. Phillip Pressley PhD Student Department of Civil, Construction, and Environmental Engineering

Transcription

1 Material Recovery Facilities Process Modeling Phillip Pressley PhD Student Department of Civil, Construction, and Environmental Engineering S WOLF 1

2 Outline Introduction Types of Material Recovery Facilities Data Development Example Equations Illustrative Results 2

3 What Is A MRF? A material recovery facility (MRF) separates an input waste stream into saleable recyclables and a residual that must be treated further (e.g., landfill, waste-toenergy) The MRF process model calculates the costs, output masses, and resource consumption for separating 1 Mg (1 metric ton) for a MRF with a particular equipment layout and facility size 3

4 Single-Stream Modeled MRF Types Accept one stream of comingled recyclables Dual-Stream Accept two waste streams (fiber, containers) Pre-Sorted Accept many streams of source-separated recyclables Mixed-Waste Accept one stream of mixed waste with no source separation 4

5 The MRF Process Model Facility Input (Mg in ) Direct Emissions (kg/mg in ) User Inputs MRF Process Model Resource Consumption (resource/mg in ) Capital Cost ($/Mg-yr -1 ) Operating Cost ($/Mg in ) Recovered Streams (Mg out ) Residual (Mg out ) 5

6 Recoverable Materials User selects recovered materials from each modeled MRF, which may include: Fiber Mixed paper OCC Glass old corrugated containers (e.g., cardboard boxes) Brown Clear Green Metals Ferrous Aluminum Plastics Film HDPE (e.g., milk jug) PET (e.g., soda bottles) 6

7 MRFS THAT PROCESS SOURCE-SEPARATED RECYCLABLES 7

8 Material Reprocessing Comingled Recyclable Collection Commingled MRF Thermal WtE Ash Landfill Mixed Waste/ Residual Collection Mixed Waste MRF Anaerobic Digestion Organics Collection Soil Amendment Composting Landfill Mixed Waste Recyclables Combustibles Organics Ash 8

9 Single-Stream MRF Process Flow 10

10 Automated vs. Manual Separation MRFs have variations in degree of automation Model flexibility is required to model MRFs with different levels of automation Manual options for material recovery have been included in the model All materials can be recovered manually except glass 11

11 Dual-Stream MRF Process Flow 13

12 Pre-Sorted MRF Process Flow 15

13 MIXED WASTE MRFs 16

14 Material Reprocessing Comingled Recyclable Collection Commingled MRF Thermal WtE Ash Landfill Mixed Waste/ Residual Collection Mixed Waste MRF Anaerobic Digestion Organics Collection Soil Amendment Composting Landfill Mixed Waste Recyclables Combustibles Organics Ash 17

15 Mixed-Waste MRF Process Flow 19

16 Data Development Little MRF data publicly available Much of the data came from discussions with MRF operators, equipment vendors, and engineering judgment Example data types: Equipment Costs Motor Size/Resource Use Separation Efficiencies Throughput Facility Costs Sizing Electricity Consumption 20

17 Sample Equipment Data Equipment Max Throughput (Mg/hr) Fraction of Equipment Capacity Utilized Fraction of Motor Rated Capacity Utilized Rated Motor Capacity (kw) Investment Cost ($) Fixed O&M Cost ($/yr) Lifetime (yr) Magnet , Eddy Current Separator ,

18 Mass Balance input mass throughput Equipment (e.g., magnet) mass of waste fraction removed (e.g., ferrous) mass of waste fraction remaining (e.g., aluminum, etc.) 22

19 m removed j,i = f separation TP j,i m j,i where: removed m j,i separation f j,i TP m j,i mass of waste fraction i removed by equipment j (Mg) separation efficiency of equipment j for waste fraction i incoming mass to equipment j for waste fraction i (Mg) 23

20 m remaining j,i = m TP removed j,i m j,i where: remaining m j,i removed m j,i TP m j,i mass of waste fraction i unaffected by equipment j (Mg) mass of waste fraction i removed by equipment j (Mg) incoming mass throughput to equipment j for waste fraction i (Mg) 24

21 Allocation Options Variations in recovered materials and downstream processing may result in changes to desired allocation stream Cost and resource use may be allocated to throughput, mass removed, or mass remaining Default configuration allocates resources to Mass removed for equipment that is only included to remove certain waste fractions (e.g., magnets, optical sorters) Total throughput for all other equipment 25

22 Sample Resource Consumption and Costs by MRF Type MRF Type Electricity (kwh/mg input ) Diesel (L/Mg input ) Wire Mass (kg/mg input ) Residual Rate (%) Total Cost ($/Mg input ) Single-Stream Mixed-Waste Dual-Stream Pre-Sorted These values should not be compared to determine which MRF is better because of inconsistent functional unit between MRF types High contamination increases equipment size and electricity demand in a mixed-waste MRF, but lower labor costs decrease the total cost compared to single-stream and dual-stream MRFs. Smaller equipment allows the dual-stream MRF to have lower costs and electricity consumption than the single-stream MRF. Pre-sorted MRFs have the lowest electricity consumption and cost because of relatively low automation. 26

23 Electricity Consumption (kwh/mg) Single-Stream MRF Electricity Consumption by Waste Composition Cascadia (2011) ODEQ (2011) Beck (2005) U.S. EPA (2010) Eddy Current Separator/Magnet Plastic Optical Sorters Glass Optical Sorter/Air Knife Glass Breaker Screen Balers Manual Sorts Disc Screens Other Warehouse Lighting Office Electricity Input waste composition impacts electricity consumption for MRFs with identical equipment layouts Only glass separation equipment requires more than 10% of total consumption Office electricity and warehouse lighting each accounts for 8% of total electricity consumption 27

24 References Pressley, P.N., Levis, J.W., Damgaard, A., Barlaz, M.A., DeCarolis, J.F., Analysis of Material Recovery Facilities for Use in Life-Cycle Assessment. Accepted Waste Management. Pressley, P.N., Aziz, T.N., DeCarolis, J.F., Barlaz, M.A., He, F., Li, F., Damgaard, A., Municipal solid waste conversion to transportation fuels: a life-cycle estimation of global warming potential and energy consumption. Journal of Cleaner Production 70, doi: /j.jclepro

25 Acknowledgments 29