Trompe: Design and Analysis of a Passive Aeration Mechanism

TROMPES “R” USBy: Michael Fox, Kevin Kraus, Nicholas Pyo

Outline

Background Approach Taken Summary of Results Sustainability Assessment Cost Assessment Guidance

History

Originated in the Catalan Forge, Spain

Used in Ragged Chute mine in North Bay, Canada

New Revival: Treatment of AMD BioMost, Inc.

What is a Trompe?

Energy Balance

( 𝑣122𝑔 +𝑃1

𝛾 +h1=𝑣22

2𝑔 +𝑃 2

𝛾 +h2)Kinetic Energy

Potential Energy

Elevation Head

Outline

BackgroundApproach Taken Summary of Results Sustainability Assessment Cost Assessment Guidance

Approach TakenProblem Statement: Investigate the problems with configurations and efficiency of trompe Limited information and knowledge of trompeObjectives: Better understanding of trompe Breaking down each component Disseminate the information as guidance Lab, Field and Computer Model

Design Criteria and ConstraintsCriteria and Constraints: Design criteria – Hydraulics

Steady Flow Design constraints

Material – PVC Water Flow:

Lab: 0 – 45 GPM Field: 0 – 3000 GPM

Lab Experiment

Independent Variables: Design of the aspirator Length and diameter of air

containment chamber Height of outflow Flow rate of water

Dependent Variables: Air production

Lab Experiment Aspirator Designs

Figure 2: One-inch trompe aspirator design.

Figure 3: Two-inch trompe aspirator design.

BioMost Field Aspirator Design

Field Monitoring-Rock Tunnel

Field Monitoring

B C D

A E

Computer Model

Developed from Energy Equation

Takes inputs (Right) Outputs graph (shown later)

( 𝑣122𝑔+𝑃1

𝛾 +h1=𝑣22

2𝑔+𝑃 2

𝛾 +h2)

Outline

Background Approach TakenSummary of Results Sustainability Assessment Cost Assessment Guidance

Air Production vs Water Flow Rate

0 50

1100 1300 1500 1700 1900

00.10.20.30.40.50.60.70.80.9

1

024681012

One-inch Lab-Scale Two-inch Lab-Scale Field-Scale

Water Flow Rate (GPM)

Air F

low

Rate

in to

Tro

mpe

(c

fm)

Air Production Efficiency

0.0 1.0

5 15 25 35 45

0.0

1.0

51015

One-Inch Trompe Two-Inch Trompe Efficiency LineField-Scale Efficiency Line 2

Air Flow Rate In (cfm)

Air F

low

Rate

Out

(cfm

)

Aspirator Model Setup

Height of Water in Reservoir

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

-5-3-113579

P in Venturi (psi) P before Venturi (psi) P after Venturi (psi) Head H2O z_5 (ft)

Flow Rate of Water (gpm)

Head

(ft)

Pressure Before Aspirator

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

-5-3-113579

P in Venturi (psi) P before Venturi (psi) P after Venturi (psi) Head H2O z_5 (ft)

Flow Rate of Water (gpm)

Head

(ft)

Pressure In Aspirator

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

-5-3-113579

P in Venturi (psi) P before Venturi (psi) P after Venturi (psi) Head H2O z_5 (ft)

Flow Rate of Water (gpm)

Head

(ft)

Pressure After Aspirator

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

-5-3-113579

P in Venturi (psi) P before Venturi (psi) P after Venturi (psi) Head H2O z_5 (ft)

Flow Rate of Water (gpm)

Head

(ft)

0 2 4 6 8 10 12 14

-5

-3

-1

1

3

5

7

9

P in Venturi P before Venturi P after Venturi Head H2O

Flow Rate of Water (gpm)

Head

(ft)

One Inch Trompe

Critical Range

20 40

-5-3-113579

111315

P in Venturi P before Venturi P after Venturi Head H2O

Flow Rate of Water (gpm)

Head

(ft)

Two Inch Trompe

Critical Range

0 100 200 300 400 500 600 700 800 900

-15

-5

5

15

25

35

45

P in Venturi P before Venturi P after Venturi Head H2O

Flow Rate of Water (gpm)

Head

(ft)

Rock Tunnel - Ten inch Trompe

Critical Range

Sensitivity Analysis

*With k_expansion > 1

0 10 20 30 40 50 60 70-20

020406080

100120

Head H2O P_head_in_asp P_head_before_asp

Flow Rate of Water (GPM)

Head

(ft)

Sensitivity Analysis-Criteria

*With k_expansion < 1

0 10 20 30 40 50 60 70-20

0

20

40

60

80

100

120

Head H2O P_head_in_asp P_head_before_aspFlow Rate of Water (GPM)

Head

(ft)

Energy Efficiency

10 15 20 25 30 35 40 4500.20.40.60.8

11.21.41.61.8

2f(x) = 0.034332534312982 x + 0.380774140202798

Energy Efficiency of 2" Trompe

Water Flowrate (GPM)

% E

fficie

ncy

010

020

030

040

050

060

070

080

00

4

8

12

16

20

Energy Efficiency of Each Field Trompe

Low

Medium

High

Water Flowrate (GPM)

% E

fficie

ncy

Outline

Background Approach Taken Summary of ResultsSustainability Assessment Cost Assessment Guidance

Air Compressor: 7.5 HP | 30 CFM Operates on 6.93 kWh Operate Compressor:

1 year 61,000 kWh

Sustainability AssessmentCarbon Emissions: Assume the burning of coal 2.10 lbs CO2 per kWh Emissions into Atmosphere:

1 year 130,000 lbs of CO2

Average Household: 15,000 lbs of CO2 per

year

That is the equivalent Emissions of 9 Houses!

That is the equivalent weight of 21.5 elephants!

Outline

Background Approach Taken Summary of Results Sustainability AssessmentCost Assessment Guidance

Cost Assessment10 Year Analysis: Average Cost of Electricity is

$0.12/kWh Air Compressor:

Cost of Structure and Install – $23,000

Cost of Operation – $73,000

Present Worth: $96,000 Trompe:

Cost of Install - $46,000 Cost of Operation - $0

Present Worth: $46,000

Trompe:$50,000 Savings!

Outline

Background Approach Taken Summary of Results Sustainability Assessment Cost AssessmentGuidance

Guidance

Key Design Elements: Critical Range

Dependent on Water Flowrate Aspirator Design

25-50% Area Reduction Air-Separation Chamber

Varying Length Following Recommendations:

Improved System Efficiency

Conclusion

Trompes needed for Passive Treatment

Lab experiments Field monitoring Calibrate computer model Design guidance and

recommendations Disseminate Information

Acknowledgements

BioMost, Inc. Kevin Tomkowski Joel Bandstra, PhD Douglas Daley, PE Kelsea Palmer Bruce Leavitt

Questions?Thank you!