Ad 2012 presentation ppt iii

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


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


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)


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%


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%


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%


Slide 8

Sampling Techniques

• Cross Stack


Slide 9

Sampling Techniques

• Dual Path Cross Stack


Slide 10

Sampling Techniques

• Open Path Probe


Slide 11

Sampling Techniques

• Demister Probe


Slide 12

Demister Probe


Slide 13

Demister Probe


Slide 14

Demister Probe


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


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


Slide 17

Response Time

• Probe volume can be calculated as a function of length:

)]"5()([2)()( 2Re

22Pr turnColdFingerColdFingerobeFlowcellsample rLrrVV


Slide 18

Detection Technology


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


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


Slide 21

Questions

Thank You for Your Attention

Questions?


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)


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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Ad 2012 presentation ppt iii