communication and measurement
TAIL GAS ANALYZER
ANALYSIS OF H2S AND SO2
The Tail Gas analyzer is part of the BAGGI BASE® Instruments
Series.
It is the r...
The Claus process is the industry standard and so the most
significant gas desulfurizing process, recovering elemental sul...
The Claus reaction to convert H2S into elemental sulfur requires
the presence of one mole of SO2 for each two moles of H2S...
Schematic flow diagram of the Claus Process:
Our scope is to supply a way to measure the presence of the
various compounds (H2S and SO2) in the process gas.
An accurat...
The Tail Gas analyzer of the BAGGI BASE® series provides
the required capabilities for the real time measurements of H2S
a...
PRINCIPLE OF MEASUREMENT
The BASE® Series Instrument can Handle many of the well know
spectroscopy techniques.
Thanks to h...
The measurement technique relies on the Beer-Lambert law. This
one is a relationship that relates the absorption of
electr...
Beer-Lambert law
In essence, the law states that there is a logarithmic
dependence between the transmission of light (or U...
The following relation holds:
I1/I0= 10- α L = 10- ε L c
where ε is the molar absorptivity of the absorber (e.g. Benzene)....
The analyzer establishes the intensity of the signal transmitted
by the lamp of the spectrophotometer and measures the
int...
The figures show some typical absorbance spectrum some
compounds (absorbance in the y-axis versus wave length in
the x-axi...
ARCHITECTURE
The BASE® Series analyzer is composed by the following
main components:
• Embedded industrial computer
• Spec...
Embedded computer
The implementation of the H2S/SO2 analyzer follows the
general philosophy of the BASE Instruments Series...
The computer is in charge of:
• Actuating the UV lamp of the spectrophotometer
• Acquiring the electrical signals from the...
The figure shows the computer’s display with the functional
keys, within the stainless steel pressurized ATEX certified
en...
Spectrophotometer
The instrument is composed of an UV lamp and a diode array.
The UV beam, after passing through the measu...
The UV/Visible band spectrophotometer schema is shown
below:
Xe Flashlamp
Lamp
Fiber optic cable
With SMA connection
Modul...
Optical Cell
The optical cell, where the process sample is traversed by the UV
beam, is made under BAGGI design and differ...
Some BAGGI design cell types are shown in the figures
belows. Cells are all modular in order to change the path
lenght:
Sampling system
The Baggi SensEvolution® products have been developed for
providing industrial analysis in many applicatio...
Sample take-off probe
A sample take-off probe
can be supplied. Probe
can be equipped with a
cooler and demister in
order t...
BASE series instruments are disigned to be modular and the
can handle many measurement principles by changing the
internal...
OTHER PRINCIPLES OF MEASUREMENT:
THE UNIQUE INTERACTION OF HYDROGEN WITH PALLADIUM
• Both resistor and capacitor circuits ...
OTHER PRINCIPLES OF MEASUREMENT:
GAS CHROMATHOGRAPHY
In a GC analysis, a known volume of gaseous sample is injected into t...
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for your attention
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tail gas H2S/SO2 analyzer

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The Claus process is the industry standard and so the most
significant gas desulfurizing process, recovering elemental sulfur
from gaseous hydrogen sulfide.
The process is commonly referred to as a sulfur recovery unit
(SRU) and is very widely used to produce sulfur from the
hydrogen sulfide found in raw natural gas and from the by-product
sour gases containing hydrogen sulfide derived from refining
petroleum crude oil and other industrial facilities.
There are many hundreds of Claus sulfur recovery units in
operation worldwide.
In fact, the vast majority of the 68,000,000 metric tons of sulfur
produced worldwide in one year is by-product sulfur from
petroleum refining and natural gas processing plants.

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Transcript of "tail gas H2S/SO2 analyzer "

  1. 1. communication and measurement
  2. 2. TAIL GAS ANALYZER ANALYSIS OF H2S AND SO2 The Tail Gas analyzer is part of the BAGGI BASE® Instruments Series. It is the result of combining the latest state-of-the-art-technology with over 60 years of industry experience. This real time process analyzer is ideal for the measurement of the percentage of H2S and SO2 within the outlet gas stream from the sulfur recovery unit process (Claus process unit). It uses ultraviolet/visible spectrophotometry for achieving very accurate results. The fully automated instrument is accompanied with a sampling loop, tailored according to the Customer’s requirements. An ATEX version is available for operation in potentially explosive atmospheres.
  3. 3. The Claus process is the industry standard and so the most significant gas desulfurizing process, recovering elemental sulfur from gaseous hydrogen sulfide. The process is commonly referred to as a sulfur recovery unit (SRU) and is very widely used to produce sulfur from the hydrogen sulfide found in raw natural gas and from the by-product sour gases containing hydrogen sulfide derived from refining petroleum crude oil and other industrial facilities. There are many hundreds of Claus sulfur recovery units in operation worldwide. In fact, the vast majority of the 68,000,000 metric tons of sulfur produced worldwide in one year is by-product sulfur from petroleum refining and natural gas processing plants. INTRODUCTION
  4. 4. The Claus reaction to convert H2S into elemental sulfur requires the presence of one mole of SO2 for each two moles of H2S: Claus gases (acid gas) with no further combustible contents apart from H2S are burned in lances surrounding a central muffle by the following chemical reaction: 2 H2S + 3 O2 → 2 SO2 + 2 H2O This is a strongly exothermic free-flame total oxidation of hydrogen sulfide generating sulfur dioxide that reacts away in subsequent reactions. The most important one is the Claus reaction: 2 H2S + SO2 → 3 S + 2 H2O The overall equation is: 10 H2S + 5 O2 → 2 H2S + SO2 + 7/2 S2 + 8 H2O
  5. 5. Schematic flow diagram of the Claus Process:
  6. 6. Our scope is to supply a way to measure the presence of the various compounds (H2S and SO2) in the process gas. An accurate analysis of the compounds composing the Tail Gas is very important in order to have a real-time monitoring and regulation of the production process. With a well run and controlled process in plant you may save time and money.
  7. 7. The Tail Gas analyzer of the BAGGI BASE® series provides the required capabilities for the real time measurements of H2S and SO2 in Tail gas stream. The method of analysis is Ultra-Violet/Visible spectrophotometry: faster, more rugged and less expensive than Gas Chromatography. The instrument provides high wavelength resolution and it can be equipped with multiple cells and spectrometer module.
  8. 8. PRINCIPLE OF MEASUREMENT The BASE® Series Instrument can Handle many of the well know spectroscopy techniques. Thanks to his modular design The BASE® Series Instrument is able to use a large area of the electromagnetic spectrum and different analytical techniques to measure many compounds. This techniques can be summarised as: - UV/VISIBLE Absorption and fluorescence - NIR / SWIR / FTIR / FTNIR Absorption, Fourier Transform - TLD Absorption
  9. 9. The measurement technique relies on the Beer-Lambert law. This one is a relationship that relates the absorption of electromagnetic waves energy to the properties of the material through which the waves are travelling. The process gas is introduced in a sample cell of a specific optical path length. The UV energy is transmitted into the cell via an optical fiber cable, it passes through the sample cell and the residual energy is transmitted to the UV sensor by a second optical fiber. The sensor is made by an array of photodiodes, each one of them tuned to a specific wavelength. Finally an embedded computer collects the electrical signals from the diode array, analyzes the absorption spectrum and calculates the concentration of the aromatic compounds.
  10. 10. Beer-Lambert law In essence, the law states that there is a logarithmic dependence between the transmission of light (or UV waves) through a substance and the concentration of the substance, and also between the transmission and the length of material that the light travels through. The measurement is targeted at the wave length band where the investigated material has maximum energy absorption.
  11. 11. The following relation holds: I1/I0= 10- α L = 10- ε L c where ε is the molar absorptivity of the absorber (e.g. Benzene). The transmission of the signal through the sample is expressed in terms of “absorbance”, which is defined as: A = -log10(I1/I0) This implies that the absorbance is linear with the concentration: A = ε L c I0= intensivity of incident signal I1= intensivity of outgoing signal L = length of the path c= substance concentration α = absorption coefficent of the substance
  12. 12. The analyzer establishes the intensity of the signal transmitted by the lamp of the spectrophotometer and measures the intensity of the signal received by the photodiode array. The signal is analyzed at wavelengths where the absorbance of the measured substance is maximal. Then the application software calculates the concentration according to the measured values and the above formulas. A multi-compounds analysis is possible, because each compound has its unique absorbance spectrum.
  13. 13. The figures show some typical absorbance spectrum some compounds (absorbance in the y-axis versus wave length in the x-axis). SO2 Spectrum at 1% concentration H2S Spectrum at 1,5% concentration
  14. 14. ARCHITECTURE The BASE® Series analyzer is composed by the following main components: • Embedded industrial computer • Spectrophotometer • Optical cells • Fiber optics • Interface modules • Solenoid valves • Power supply • Sampling system • Sample take-off probe
  15. 15. Embedded computer The implementation of the H2S/SO2 analyzer follows the general philosophy of the BASE Instruments Series. The raw input data from the sensors (UV spectrophotometer) are processed by algorithms provided by BAGGI, running in an embedded computer that is the heart of the system. When required, an ATEX version is available. In this case the computer, together with the spectrophotometer and the power converters, is within an enclosure provided with a protective purge system and an optional Vortex cooler (connected to the plant instrument air system).
  16. 16. The computer is in charge of: • Actuating the UV lamp of the spectrophotometer • Acquiring the electrical signals from the CCD array (related to the intensity of the absorbed light) • Calculating the concentration of the compounds • Controlling the residual lifetime of the Xenon lamp • Actuating the pumps and the valves • Actuating the digital/analog conversion for outputting the calculated values over 4…20 mA signals • Interfacing the digital bus (e.g. Modbus) • Actuating the output relays for handling the alarms • Displaying the system status and the measurement data in a Graphical User Interface (GUI) • Storing the status and the measurement archives into a data base (CSV format) • Interfacing the human operator for system calibration and maintenance transmitting remotely the information/alarms via serial lines, Ethernet and WiFi;
  17. 17. The figure shows the computer’s display with the functional keys, within the stainless steel pressurized ATEX certified enclosure or explosion proof ATEX enclosure:
  18. 18. Spectrophotometer The instrument is composed of an UV lamp and a diode array. The UV beam, after passing through the measurement cell, reaches a holographic grating disk. This one diverts each wavelength composing the beam onto a specific diode of the array. The voltage emitted by the individual diodes is measured and this information is acquired by the embedded computer through a serial line. There are no moving parts. The computer knows the amount of UV energy that has been transmitted by the lamp and is able to draw the absorption spectrum. Finally it calculates the concentration of the components. The spectrophotometer is controlled by the computer by means of an internal USB/RS232 line and is housed in the same enclosure.
  19. 19. The UV/Visible band spectrophotometer schema is shown below: Xe Flashlamp Lamp Fiber optic cable With SMA connection Modular Flow cell Collimator and window Holographic grating Diode array Sample fluid inlet Sample fluid outlet
  20. 20. Optical Cell The optical cell, where the process sample is traversed by the UV beam, is made under BAGGI design and different material can be provided: - AISI 316L stainless steel. - Hastelloy C276 - Monel - Glass - Other on request available The length of the cell is a function of the range to be measured. The smaller the concentration, the longer is the cell. When the measured values can span a wide range, there is the option of using two different cells connected in parallel. The computer is able to select dynamically the cell more appropriate for the actual value.
  21. 21. Some BAGGI design cell types are shown in the figures belows. Cells are all modular in order to change the path lenght:
  22. 22. Sampling system The Baggi SensEvolution® products have been developed for providing industrial analysis in many application fields. The SensEvolution Sample® line comprises all the sampling products developed for the SensEvolution® instruments and analysers, but also special executions made under specific customers’ requirements. For the Tail Gas analyzer an insulated and heated sampling system is provided in order to keep the temperature of the sample gas about at 120°C to avoid presence of solid sulfur inside tubing. As per customer specification, heater system can be composed of electrical or steam heated pipes or by an electric atex heater.
  23. 23. Sample take-off probe A sample take-off probe can be supplied. Probe can be equipped with a cooler and demister in order to eliminate water contents Filters, pressure and temperture gauges can be directly mounted on the process probe to have a real-time monitoring of the sample point.
  24. 24. BASE series instruments are disigned to be modular and the can handle many measurement principles by changing the internal sensor unit: - UV/VIS - NIR SPECTROSCOPY - GAS CHROMATOGRAPHY - PHOTO-IONIZATION DETECTION - ELECTROMAGNETIC ENERGY ABSORPTION - PALLADIUM SENSORS
  25. 25. OTHER PRINCIPLES OF MEASUREMENT: THE UNIQUE INTERACTION OF HYDROGEN WITH PALLADIUM • Both resistor and capacitor circuits for hydrogen measurement capability from 15ppm to 100% v/v • Palladium – Nickel alloy provides stable operation in pure hydrogen at multiple atmospheres) • On die temperature sensor and heater compensates for variations in gas flow, gas composition and gas temperature. • Unique semi-permeable coatings enable continuous operation in a wide range of gas mixtures including harsh environments Molecular hydrogen (H2) adsorbs on palladium and dissociates into atomic hydrogen (2H) Atomic hydrogen is reversibly absorbed into palladium proportional to H2 partial pressure
  26. 26. OTHER PRINCIPLES OF MEASUREMENT: GAS CHROMATHOGRAPHY In a GC analysis, a known volume of gaseous sample is injected into the head of the column. As the carrier gas sweeps the sample molecules through the column, this motion is inhibited by the adsorption of the sample molecules either onto the column walls or onto packing materials in the column. The rate at which the molecules progress along the column depends on the strength of adsorption of each molecule. Since each type of molecule has a different rate of progression, the various components of the sample mixture are separated as they progress along the column and reach the end of the column at different times (retention time); thus, the time at which each component reaches the outlet and the amount of that component can be determined.
  27. 27. Thank you for your attention
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