The project aims to design a process to remove limonene from waste tire oil at an existing plant, improving profits and oil quality. The most economical method is to thermally crack limonene into isoprene and then reform limonene by dimerizing isoprene. This creates lighter and heavier streams for simpler purification, reducing costs. The process yields limonene and improved waste oil, with estimated costs, profits, and investment metrics showing strong returns over a 2 year payback period.

1. The purpose of the project was to design a useful,
economically feasible add-on process with as many
specifications as possible to an existing plant that
creates tire oil as a waste product. The goal is to
remove limonene from the waste tire oil stream,
improving the profit of the plant and the quality of
the remaining oil.
The most economical method to recover limonene
from waste tire oil is to thermally crack the limonene
into isoprene and later reform the limonene by
dimerization. The advantage of this method is the
formation of light chemicals in an otherwise heavy
stream in the limonene reactor and the formation of
heavy chemicals in an otherwise light stream in the
isoprene reactor. The difference in the component
boiling points in each stream makes purification of
the final product simpler and reduces operating
costs.
Product: Limonene (80%, Industrial)
Basis (gal/hr) 3
Operating Time (h/yr) 7440
Sales Price ($/gal) $77
Product: Improved Reklaim Oil
Basis (L/hr) 62
Operating Time (h/yr) 7440
Sales Price ($/gal) $1
Direct-Production Cost $373,000
Fixed Charges $325,000
Plant Overhead Costs $140,000
Factory-Manufacturing Cost $838,000
General Expenses $400,000
Total Product Cost $1,238,000
Total Income $2,180,000
Fixed-Capital Investment $2,368,000
Working Capital $552,000
Total Capital Investment $2,920,000
Gross Earnings Before Taxes $942,000
Net Profits after 35% taxes $612,300
Average Annual ROI 21%
Payout Time (years) 2.0
Net Present Worth $2,400,000
Discounted Cash Flow ROI 23.1%
Process Conversion
Cracking Limonene to Isoprene 95%
Dimerizing Isoprene to Limonene 16%
Months 1 2 3 4 5 6 7 8 9 10 11 12
Additional Lab Scale Experiments
Site Analysis
Final Pilot Plant Sizing
Permitting
Order Parts and Equipment
Construction
Start-Up
Monitoring
Optimization
Isoprene to Limonene SetupBench Scale Cracking Apparatus
Feed: 65 gallons per hour, 5% limonene, $0.37/gallon
Limonene Product: 3 gallons per hour, 80% limonene, $77/gallon
Improved Waste Oil: 62 gallons per hour, 0% limonene, $1/gallon
Sponsors:
Major John Riggins, Retired USAF