Remediation of Crude Oil Impacted Soils with Electron Beam Irradiation

Transcription

1 A15-03 Remediation of Crude Oil Impacted Soils with Electron Beam Irradiation John Lassalle, Marco Martinez, Thomas Thompson, Kenneth Briggs, Harika Damarla, Craig Evangelista Andrea Strzelec, David Staack (Mechanical Engineering Texas A&M University, College Station, TX, USA) Paul Bireta, Deyuan Kong, Thomas Hoelen, and Gabriel Sabadel (Chevron) 1

2 Motivation and Objectives Pollution of soils by heavy hydrocarbons is a major global environmental issue [1]. Light Crude Oil very mobile, bioremediate or weather away Very Heavy Oil asphalt immobile & acceptable Mid Heavy Oil don t weather or bioremediate easily, moderate mobility, nuisance Remediation technologies must be fast, efficient, and economical at large scales Niger River Delta [P1] Objectives: Show proof of concept (TPH reductions to <1%) Impact of test parameters such as dosage Design of experiment setup Picture of Rock Bay Crude Oil Remediation Site 2

3 Background 1. TPH = Total petroleum hydrocarbon Measure of hydrocarbon (C 6 thru C 40 ) content in the soil. Initial 3% - 5% Oil w/w Goal (industrial) < 1% Goal (non-industrial) < 0.15% 2. Typical Thermal & Energetic Removal Methods Direct Heating - (flame on soil heat to 500 o C) Indirect Heating kiln drying (heat to 500 o C) Oxidation & Combustion occurs in direct heating Pyrolysis occurs in high temperature kiln drying (inert gas) Combustion Pyrolysis 3

4 Conceptual e-beam Process Overview Schematic Excavation Conveyor Conveyor E-beam Processing (mobile facility brought to site) MW, 10 MeV Electron Beam Crushing & Sizing Stockpiling Radiation Shielding Necessary only when beam is on. No residual radiation. Treated Soil Condensation of desorbed vapors Gas Treatment / Air Quality Control Backfill with Treated Soil Soil stays on site Soil Amendments Water Oil 4

5 Temperature [ C] Why e-beam? Advantages: Higher rate of energy addition than all other energetic methods Production of char (fixed carbon with potential benefits for soil health) Soil Temperature-All Treatments Time [min] Held for 200 m Industrial Thermal Desorption Pyrolysis Electron Beam - Radiation chemistry speeds up pyrolysis cracks (easier to remove) or polymerizes (reduces mobility) some medium-heavy hydrocarbons. - Oils can be recovered from the soils - Volumetric heating simplifies material handling, potentially enables separation of liquid crude oil. Disadvantages: Higher specific energy requirements (x2) than thermal methods Need radiation shielding during operation Penetration depth 5

6 E-beam processing facility concept Trailer mounted portable ebeam. On site, ex-situ Shown below is a single 800 kw, 8 MeV beam (Rhodotron) 100 CY / day, 10 ft/min feed, 8 second residence time ~70ft Top ¼ of soil exits. Bottom ¾ captures residual heat and dries input soil prior to ebeam to ~10% water content. 6 6

7 Experimental Methods Experimental configurations Small batch 100g preliminary experiments Stationary large batches for dose matching Conveyed 3 kg samples (1 to 5 inches/minute) Various Soils Tested Synthetic Manufactured Mixtures (crude + dirt) Field Attained Soils (GSC1AOS, GSI14RD, BTSludge) Benchmark Soils (BM1, BM2, TX1) Dose ranges from 200 to 2500 kj/kg at 6-10 kgy/s. 30s to 6 min residence time for irradiation. UV-Vis Absorption, Colorimetry for screening tests, Gas chromatography, Lancaster Labs for Third Party evaluation of TPH, TPO/TPD (fixed and mobile carbon). 7

8 Video of Processing 8

9 Still from Video 9

10 TPH (% mass) Processing Results TPH DCM extracted PH Increasing dose GSC1AOS GSI14RD BM1 BM Dosage (kgy) 10

11 Max Temperature vs. Energy Input 11

12 mg/kg in soil sample % Fraction of TPH TPH Results GSC1AOS Soil % 10.0% 8.0% 6.0% 4.0% GSC1AOS 1100 kgy GSC1AOS 720 kgy GSC1AOS 0 kgy GSC1AOS 1100 kgy GSC1AOS 720 kgy GSC1AOS 0 kgy ~ Carbon Number Proportional removal of heavier fractions No preferential removal TPH decreases with dosage in the DRO and ORO ranges. GRO increases w/ dosage Maximum reduction: 9.1% 0.5% Thermal effects more dominant at high doses. Non-thermal processing 2.0% 0.0% ~ Carbon Number Large increase in GROs for highest dose 12

13 SJV Soil Treatment Cross Section 8.02 cm Heavily treated moderately treated Got oily from condensation 1 cm 2 cm 3 cm 4 cm Still clean Unaffected 13

14 TPD / TPO Analysis MS TOTAL CARBON TPD TPO (a) is TPO (incineration) comparison for untreated and treated, shows that there is less combustible material in the treated sample. (b) is TPD+O (volatilization) comparison for untreated and treated samples, shows that there is much less volatile content on the treated than the untreated sample, and the only volatile content that is there is 'heavy'. (c) is the TPD+O then TPO (volatilization then incineration) for the untreated and treated samples. There is considerably more fixed carbon in the treated sample as compared to the untreated. However there is over all less carbon. This indicates that the treatment has volatilized a portion of the hydrocarbons and converted some of the hydrocarbons to char. DESORBABLE CARBON FIXED CARBON 14

15 Competitive Economics ($/CY) Industrial Thermal Desorption is exiting / completing technology Economic comparison cannot only consider energy requirements Case study 100 CY/day, 6 mos. direct e-beam thermal Energy cost processing Capital cost energy addition Capital cost exhaust handling 5 20 Energy cost exhaust handling 1 5 Material excavation and loading Site setup and security 7 4 Site setup and security 7 4 Post treatment ph amendment 1 4 Post treatment organic matter amendment 0 4 Post treatment nutrient amendment 5 5 Condensed Hydrocarbon (30% recovery) value -4 0 Soil amendment value -2 0 Total

16 Summary - Electron Beam Remediation of Soils Proof of Concept Benchmark and field attained soils successfully tested. Can extinguish the environmental liability (<1% TPH), conceivably onsite. TPH can be reduced to <1% for 500 to 1000 kj/kg increasing with initial contamination 1.6% to 9.1%. Mechanisms: Analysis of hydrocarbon distribution indicates 1) Thermal Desorption effect 2) Low temperature & rapid pyrolysis effects (Char formation) 2) additional non-thermal process characteristics i) electron beam initiated cracking and production of GRO ii) low temperature Char formation by e-beam radicals iii) proportional removal of DRO and ORO components Electron beam is safe (not a radiation source) when off, and shield-able with site materials. Other Factors: Fines & Exhaust Handling, Soil Amendments, No upper limit of TPH contamination. Progressing toward industrial scales Beam & Treatment profiles Laboratory scale conveying systems Future testing at industrial rates in 10 MeV, 100 kgy/s facility 16

17 Thanks for your attention Thanks to the National Center for Electron Beam Research at Texas A&M University for allowing us to do research on novel processing technologies Thanks to Chevron for sponsoring this research 17

18 Hydrocarbon Content from Colorimetry [% mass] Hydrocarbon Content vs. Energy Input Specific Energy Input [kj/kg], Dose [kgy] 19-Feb 12-Jan Moist 12-Jan Dry 31-Mar 29-Jul 3-Sep 15-Oct 27-Oct Untreated 18

19 Temperature ( C) Wet Dry Beam Motion 600 Results-Dry Section Thermocouple Data for Dry Section Test Max temperature higher for TC 7 than TC despite same dose, suggesting heating by adjacent soil. The soil near TC 7 also 100 appears to have a lower TPH than the soil near TC Time (s) Thermocouple 7 Thermocouple 8 Thermocouple 1 Thermocouple 4 Thermocouple 6 Thermocouple 5 1:10 1:40 1:80 1:160 TC 5 TC 6 TC 7 TC kgy % 0.57% 0.285% % ~0.75% ~0.5% ~0.3% ~0.75% 19

20 Specific Energy Cost Comparison Industrial Thermal Desorption (TPH < 0.2%) For c p ~1.5 kj/kg- C and T~420 C (from experiment in Tube Furnace) Specific Energy Input = 630 kj/kg η thermal ~ 50% losses to environment from chemical energy conversion to direct heating (specification from Vulcan TDU manufacturer) Specific Energy Input = 1260 kj thermal /kg soil e-beam (TPH < 0.2%) For Dose, D 650 kgy = 650 kj/kg η= 60% e-beam generator efficiency (from MEVEX e-beam manufacturer) Specific Energy Input =1080 kj elecrtric /kg soil Electrical Energy Cost (~ 2 kj thermal /kj electric ) Specific Energy Input = 2160 kj thermal /kg soil Pyrolysis (TPH < 0.2%) ITD + hold time (energy use during hold is configuration dependent 90 kj/kg, ~5 CY system) Specific Energy Input = 720 kj/kg η thermal ~ 40% from chemical energy due to indirect heating (specification from Vulcan TDU manufacturer) Specific Energy Input = 1800 kj thermal /kg soil Ozone (target TPH not achieved independently) 1 kg ozone / kg TPH, 10 kw-hr / kg ozone, 900 kj electric /kg soil Specific Energy Input = 1800 kj thermal /kg soil ) 2 0

21 Soil Analysis Conductivity (μmho/cm) Pyrolysis Electron Beam Industrial Thermal Desorption Background Untreated Pyrolysis Electron Beam ph Industrial Thermal Desorption Background Untreated Micronutrient Content ( BG normalized) 250% 200% 150% Pyrolysis Electron Beam Industrial Thermal Desorption Background 100% 50% 0% NO3N P K Ca Mg S Na Fe Zn Mn Cu B 21