An overview of using near infrared (NIR) instrumentation to measure moisture in frac sand. Presented by Marty Peters at 2020 North America Frac Sand Conference

1. Best Practices for Using Near Infrared
Instrumentation for the Frac Sand Industry

2. Presented by:
Marty Peters, Technical Services
Process Sensors Corp., a KPM Analytics Company.
Milford, MA USA
North America Frac Sand Exhibition and Conference
February 27, 2020, Houston TX
Best Practices for Using Near Infrared Instrumentation
for the Frac Sand Industry

3. Best Practices for Using Near Infrared (NIR) for Frac Sand
• Moisture and Temperature in frac sand application
• Installation of NIR analyzers for moisture in frac sand
• NIR principles and measuring technique
• Specific practices to standardize measurements
Agenda

4. • Moisture
• Temperature
NIR Measurements for
Frac Sand for Lab & Process Spectrophotometers

5. • Moisture impacts the drying efficacy of the frac sand.
• Measuring the moisture in frac sand before a dryer allows
operators to better control the dryer. It also allows a “feed
forward” control of a dryer.
• The selection of NIR wavelengths is also critical to
successful measurements.
• The secondary moisture peak (1420nm) should be selected.
Moisture Measurement Critical

6. • Moisture can also be measured at the Outlet of a Dryer.
• Measuring the frac sand at the Outlet of a Dryer allows an
operators to ensure the Final Moisture is in specification. It
also allows a “feed back” control of a Dryer.
• While this location has not often be used it is a very
accurate measurement.
• Samples at this location can also be tested in a Laboratory
using a Bench Top Near-Infrared Analyzer.
Outlet of a Dryer Moisture Measurement

7. • Proper installation of NIR analyzers is very important for a
successful moisture measurement.
• A plow should be used prior to the analyzer. This will
achieve a constant height and a fresh sample.
• There needs to be an ample amount of sand (2” or more)
and no gaps on a conveyor
Installation of NIR Analyzers

8. Typical Frac Sand Installation

9. Typical Frac Sand Installation

10. Typical Frac Sand Installation

11. • Near-Infrared Analyzers are in the 1000nm – 2500nm
spectrum.
• The Measuring Technique is a well-established method in
many Industries and have been used to measure
Moisture, Oil/Fat, Protein and other constituents.
• In Frac Sand, Near-Infrared Analyzers are measuring the
H-O-H Bonds that absorb energy at specific wave-
length, usually at 1420nm or 1940 for dry frac sand.
Near-Infrared Principles

12. Light Wavelengths / Frequencies

13. Moisture Near Infrared Absorption Curve
Moisture Near Infrared Absorption Curve

14. NIR Functional Groups

15. NIR Photometer

16. • Samples should be collected as close to the analyzer
as possible, preferably after the analyzer.
• If this isn’t possible, the time between the sample
location and when the frac sand is under the analyzer
should be determined.
Sample Collection and Location

17. • Open containers are not suitable for sample
collection.
• Use zippered freezer bags or other sample bags
with moisture barrier coatings, with excess air
squeezed out.
• Closed containers with minimum air space are
acceptable.
Sample Collection

18. • The higher cost of sample collection containers/bags
is negligible. The key is to keep the sample from
“Picking up or losing Moisture” before laboratory
analysis.
• Reducing moisture loss/gain before laboratory testing
will increase the accuracy of the calibration.
• Consistent sample handling and duplicate sample
testing will increase accuracy of the calibration.
Importance of Sample Collection/Testing/Containers/Bags

19. • A convection oven is the best method for laboratory
testing. A 100-gram sample is recommended.
• The use of a pan and hot plate/burner is also acceptable.
• A 100-gram sample is recommended.
• Duplicate sample analysis is also recommended.
Weigh, Dry, Weigh

20. • Each company has their own practice for each product.
• 105⁰ C and 120⁰ C are most common.
• Two hours dry time is usually sufficient, and three
hours or 24 hours offers minimum additional benefit.
Time for Sample Oven Dry Product Dependent

21. • There are many moisture balances available for laboratory
testing.
• A moisture balance is an acceptable method for moisture in
Frac Sand analysis. It can provide a laboratory method to
determine the moisture content in a sample. The average
test time is 5 – 10 minutes.
• Performing the analysis in duplicate will increase accuracy.
Moisture Balance

22. Frac Sand Sample Unsealed Sample Sealed Sample
1A 5.0 5.1
1B 5.1 5.3
2A 7.2 7.3
2B 7.1 7.0
3A 9.5 9.3
3B 9.7 9.7
Comparison of Duplicate Double-Blind Samples Between
Open and Sealed Collection

23. Process Moisture Measurement is
More Accurate Due to Sample Collection Methods
Process Moisture Measurement is
More Accurate Due to Sample Collection Methods

24. LabMoisture
NIR Transmitter
NIR Transmitter Measurement
Lab vs. NIR Measurement

25. • Sample collection is important to ensure
accurate analysis of process samples.
• Air space for samples collected must be
minimized.
• Samples must be analyzed in a timely manner.
Accurate Laboratory Methods

26. Quality Control Measurements for Rapid Analysis

27. • NIR analyzers provide very accurate and
fast methods of determining moisture in
frac sand in 5 – 10 seconds.
• They will require the same calibration
methods as online NIR analyzers.
• Once calibrated, they can be used to
confirm the accuracy of online analyzers.
• They can be used to provide a quick
analysis of moisture in dried frac sand.
NIR Laboratory Analyzers

28. • Near-Infrared Analyzers provide a reliable and
accurate Moisture Measurement.
• Frac Sand Plants will be able to continuously monitor
the Moisture and control their Dryers saving energy
and re-work costs.
• Near-Infrared Analyzers will allow Frac Sand plants to
provide their customers with consistent and in-
specification product.
Conclusion

29. Martin Peters, Technical Services
Process Sensors Corp.
113 Cedar Street
Milford, MA 01757 USA
(508) 473-9901
www.processsensors.com
mpeters@processsensors.com
Thank you for your attention!
Questions?
Best Practices for Using Near Infrared Instrumentation
for the Frac Sand Industry