California or Bust, ISA AD is a Must…….See us in Anaheim 2012The 57th Annual Symposium of the Analysis DivisionAnaheim, California, USA; 22-26 April 2012
AD.12.04.02The Analysis In-Situ-ation
Approximating True In-situ Process Analysis in Sulfur Recovery and Beyond
Matt Brown, David Greaves
Daniel Murphy, Sam Rolley
Applied Analytics, Inc.
California or Bust, ISA AD is a Must……See us in Anaheim 2012The 57th Annual Symposium of the Analysis DivisionAnaheim, California, USA; 22-26 April 2012
Slide 2
Topics of Discussion
• Introduction
• SRU Applications
• Sampling Techniques
• Comparison
• Response Time
• Detection Technology
• Conclusions
California or Bust, ISA AD is a Must……See us in Anaheim 2012The 57th Annual Symposium of the Analysis DivisionAnaheim, California, USA; 22-26 April 2012
Slide 3
Introduction
• Sampling falls in two categories: – Extractive
• Sample is removed from piping• Sample conditioned to suit analysis method
– In-Situ• Sample remains inside piping• Analysis method designed to suit sample
California or Bust, ISA AD is a Must……See us in Anaheim 2012The 57th Annual Symposium of the Analysis DivisionAnaheim, California, USA; 22-26 April 2012
Slide 4
The advantages of in-situ measurement • Faster analytical response
• Unaltered, genuine sample
• Reduced maintenance due to fewer parts
• Reduced utility requirements (no heating required for the sample transport line; no utilities required for sample conditioning)
California or Bust, ISA AD is a Must……See us in Anaheim 2012The 57th Annual Symposium of the Analysis DivisionAnaheim, California, USA; 22-26 April 2012
Slide 5
Applications – Claus Process
• Converts H2S to solid sulfur
• H2S is combusted:– 3H2S+3/2O2→SO2+H2O+2H2S
• Then reacted with SO2:– 2H2S+SO2→2H2O+3/xSx
• Air Demand measurements are critical for control.
Normal Temperature 133CNormal Pressure0.35BarFluid Component Conc.Hydrogen 1.91%Argon 0.59%Nitrogen 59.83%Carbon Monoxide 1.49%Carbon Dioxide 10.22%Hydrogen Sulfide 1.07%Carbonyl Sulfide 0.11%Sulfur Dioxide 0.56%Carbon Disulfide 0.04%Water 34.17%S (Vapor) as Sx 0.01%S (Liquid) as S1 0.01%
California or Bust, ISA AD is a Must……See us in Anaheim 2012The 57th Annual Symposium of the Analysis DivisionAnaheim, California, USA; 22-26 April 2012
Slide 6
Applications – Sulfur Pit
• Liquid sulfur stored in concrete pits.
• H2S collects in vapor above pit.
• Measurement is a critical safeguard for personnel.
Normal Temperature 188CNormal Pressure0barFluid Component Conc.Hydrogen Sulfide 0.5%Oxygen 19.82%Water 5.1%Nitrogen 74.57S1 .002%
California or Bust, ISA AD is a Must……See us in Anaheim 2012The 57th Annual Symposium of the Analysis DivisionAnaheim, California, USA; 22-26 April 2012
Slide 7
Applications – Feed Forward
• Furnace used to convert H2S to SO2.
• Air flow adjusted in line with incoming H2S concentration.
• H2S measurement critical to prevent catalyst damage.
Normal Temperature 61CNormal Pressure0.9BarFluid Component Conc.Hydrogen 0.0083%Nitrogen 0.0028%Methane 0.66%Carbon Dioxide 26.58%Ethane 0.24%Hydrogen Sulfide 62.53%Carbonyl Sulfide 0.00%Carbon Disulfide 0.0005%Water 9.63%Propane 0.228%C6+ 0.091%Methyl Mercaptans 0.029%Ethyl Mercaptans 0.0053%
California or Bust, ISA AD is a Must……See us in Anaheim 2012The 57th Annual Symposium of the Analysis DivisionAnaheim, California, USA; 22-26 April 2012
Slide 8
Sampling Techniques
• Cross Stack
California or Bust, ISA AD is a Must……See us in Anaheim 2012The 57th Annual Symposium of the Analysis DivisionAnaheim, California, USA; 22-26 April 2012
Slide 9
Sampling Techniques
• Dual Path Cross Stack
California or Bust, ISA AD is a Must……See us in Anaheim 2012The 57th Annual Symposium of the Analysis DivisionAnaheim, California, USA; 22-26 April 2012
Slide 10
Sampling Techniques
• Open Path Probe
California or Bust, ISA AD is a Must……See us in Anaheim 2012The 57th Annual Symposium of the Analysis DivisionAnaheim, California, USA; 22-26 April 2012
Slide 11
Sampling Techniques
• Demister Probe
California or Bust, ISA AD is a Must……See us in Anaheim 2012The 57th Annual Symposium of the Analysis DivisionAnaheim, California, USA; 22-26 April 2012
Slide 12
Demister Probe
California or Bust, ISA AD is a Must……See us in Anaheim 2012The 57th Annual Symposium of the Analysis DivisionAnaheim, California, USA; 22-26 April 2012
Slide 13
Demister Probe
California or Bust, ISA AD is a Must……See us in Anaheim 2012The 57th Annual Symposium of the Analysis DivisionAnaheim, California, USA; 22-26 April 2012
Slide 14
Demister Probe
California or Bust, ISA AD is a Must……See us in Anaheim 2012The 57th Annual Symposium of the Analysis DivisionAnaheim, California, USA; 22-26 April 2012
Slide 15
Sampling Comparison
Cross Stack• Near impossible to
validate and zero
• Optical alignment issues
• Cannot remove optics for cleaning during operation
Demister Probe• Span and zero gas easily
introduced to flow cell
• Optics always aligned
• Optic cleaning may be automated with steam
California or Bust, ISA AD is a Must……See us in Anaheim 2012The 57th Annual Symposium of the Analysis DivisionAnaheim, California, USA; 22-26 April 2012
Slide 16
Response Time
• Adjusting the nozzle width of the aspirator produces a distinct flow-curve
• Setting the nozzle width at the maxima ensures the best performance
California or Bust, ISA AD is a Must……See us in Anaheim 2012The 57th Annual Symposium of the Analysis DivisionAnaheim, California, USA; 22-26 April 2012
Slide 17
Response Time
• Probe volume can be calculated as a function of length:
)]"5()([2)()( 2Re
22Pr turnColdFingerColdFingerobeFlowcellsample rLrrVV
California or Bust, ISA AD is a Must……See us in Anaheim 2012The 57th Annual Symposium of the Analysis DivisionAnaheim, California, USA; 22-26 April 2012
Slide 18
Detection Technology
California or Bust, ISA AD is a Must……See us in Anaheim 2012The 57th Annual Symposium of the Analysis DivisionAnaheim, California, USA; 22-26 April 2012
Slide 19
Absorbance Spectroscopy
• Beer-Lamberts Law– A(λ) = ε(λ) x b x c
• A= Absorbance• ε = Molar Absorptivity• b = Path Length• c = Concentration
• When solved for concentration– c = A(λ) / [ε(λ) x b]
• [ε(λ) x b] is an experimentally derived constant
California or Bust, ISA AD is a Must……See us in Anaheim 2012The 57th Annual Symposium of the Analysis DivisionAnaheim, California, USA; 22-26 April 2012
Slide 20
Conclusions
• Demister probe used with UV-VIS diode array spectrophotometer most practical technique– Better Accuracy– Low Maintenance– Increased Safety
• Pure cross-stack in-situ problematic– Difficult Validation– Downtime and Maintenance– Misalignment Reduces Accuracy
California or Bust, ISA AD is a Must……See us in Anaheim 2012The 57th Annual Symposium of the Analysis DivisionAnaheim, California, USA; 22-26 April 2012
Slide 21
Questions
Thank You for Your Attention
Questions?
California or Bust, ISA AD is a Must……See us in Anaheim 2012The 57th Annual Symposium of the Analysis DivisionAnaheim, California, USA; 22-26 April 2012
Slide 22
• The advantages of in-situ measurement are significant and intuitive. These advantages include, but are not limited to:
• Faster analytical response
• Unaltered, genuine sample
• Reduced maintenance due to fewer parts
• Reduced utility requirements (no heating required for the sample transport line; no utilities required for sample conditioning)
California or Bust, ISA AD is a Must……See us in Anaheim 2012The 57th Annual Symposium of the Analysis DivisionAnaheim, California, USA; 22-26 April 2012
Slide 23
• Safety. When hydrogen sulfide (H2S) is involved in an application, drawing a sample out of the process and into the human working environment is not a sound protocol. The process gas is toxic, corrosive, and flammable, and should be restrained to the pipeline if possible (EPA 2003).
• Response Time. Especially within the Claus process and feed forward applications, real-time measurement is of utmost importance for establishing tight process control. Efficiency in these processes is reliant on adjusting available air based on the H2S concentration at the precise present moment. Adjusting the air parameter based on lagged measurements introduces inefficiency (Rollo 2007).
• Reduced Maintenance. If there is no sample transport line, there is no vulnerability to line plugging or malfunction. In processes that have incident elemental sulfur, there is a looming threat that sulfur will cool, condense, and plug any mechanical cavities. Removing the sample line from the design removes this concern from the maintenance regimen.
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