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Los Angeles November 10, 2008 API 73 rd Fall Refining and Equipment Standards Meeting.

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Presentation on theme: "Los Angeles November 10, 2008 API 73 rd Fall Refining and Equipment Standards Meeting."— Presentation transcript:

1 Los Angeles November 10, 2008 API 73 rd Fall Refining and Equipment Standards Meeting

2 Combustion Analysis Options for Process Heaters David Fahle – VP of Marketing Hydrocarbon Processing

3 ENABLE YOU TO GO FURTHER precision and expertise

4 Industrial Gas Hydrocarbon Processing OEM Transducers Product Support Committed to your Success Quality Focus Process Oxygen Photometric Combustion Laser OEM transducers Analytical Systems Experts in Gas Analysis Paramagnetic Zirconia Photometric Thick Film Tuneable Diode Laser MarketsProductsTechnologySupport Gas Analysis is what we do - And we do it best

5 Servomex Proud 50 Year History Servomex Controls Limited formed1952 First paramagnetic cells made based on licence from Distillers1961 Bought by Sybron Corporation and integrated into Taylor Instruments Group1971 MBO from Sybron Corporation1987 Stock market flotation (London Stock Exchange)1989 Acquired by The Fairey Group1999 The Fairey Group renamed as Spectris plc2001

6 Global Presence

7 Combustion Applications

8 Index of Applications  Thermal power generation  Incineration  Hydrocarbon Processing  Industrial Gases  Specialty Chemicals and Pharmaceuticals  Cement  Iron and steel

9  Hydrocarbon Processing

10 Process Heaters Direct-fired heat exchanger that uses the hot gases of combustion to raise the temperature of a feed flowing through coils of tubes aligned throughout the heater. Typical temperatures 400°C-550°C ( °F) Thermal Crackers Heat exchanger where reactions take place while the feed travels through the tubes, i.e. Ethylene cracking furnace. Typical temperatures 980°C-1200°C ( °F) On-site Incinerators Designed to combust both solid and liquid chemical waste. The type depends upon the type of waste being disposed and include fluidized bed, multiple hearth and rotating kiln incinerators. Typical temperatures 1100°C (2000°F) or greater. Application Types  Hydrocarbon Processing

11 Application Types  Hydrocarbon Processing Process Heaters and Thermal Crackers - pipes run inside heating chamber to transfer heat

12 Why measure gases during combustion? Detecting oxygen rich conditions: O 2 measurement Detecting fuel rich conditions: CO measurement Combustion Analyzer Types

13 Complete Combustion C x H y + (x+( y / 4 ))O 2  xCO 2 + ( y / 2 )H 2 O + HEAT FUEL + OXYGEN  CARBON DIOXIDE + WATER + HEAT Combustion: Why measure gases?

14 Ideal CO O2O2 FUEL RICH incomplete combustion Too little oxygen = some fuel not burnt: 2000ppm excess CO above ideal means 1% extra fuel cost % Combustion Efficiency % Excess Air

15 Ideal CO O2O2 AIR RICH complete combustion Too much air = cooling effect: 1.5% excess oxygen above ideal means 1% extra fuel cost FUEL RICH incomplete combustion Too little oxygen = some fuel not burnt: 2000ppm excess CO above ideal means 1% extra fuel cost % Combustion Efficiency

16 NOx FUEL RICH AIR RICH IDEAL EFFICIENCY O2O CO Combustion Efficiency % Excess Air

17 Review - Breakthrough Concept Example 1: Coal data, 10h sample

18 Review - Breakthrough Concept Example 1: Coal data, 1h

19 Review - Breakthrough Concept Example 1: Coal data, 5mins

20 Review - Breakthrough Concept Example 2: Gas data, 3 week sample

21 Review - Breakthrough Concept Example 2: Gas data, 10h sample

22 NOx FUEL RICH AIR RICH IDEAL EFFICIENCY O2O CO Combustion Efficiency % Excess Air

23 How can oxygen be measured? Paramagnetic High accuracy Need extractive sample system with moisture removed “Zirconia” (zirconium oxide, ZrO 2 ) based analysers Suitable accuracy, measure hot and wet Fast analysis, low maintenance and low cost Tuneable Diode Laser In-situ analysis Hot, corrosive, particulate latent samples Combustion Control: O 2 Measurement Detecting air rich conditions

24 ParamagneticTechnology

25 Oxygen is unique. It is strongly attracted into a magnetic field. It is described as being “ paramagnetic ” O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 O2O2 CO CO 2 SO 2 HCl N2N2 NO N2N2 O2O2 O2O2 CO CO 2 SO 2 HCl N2N2 NO 2 O2O2 O2O2 O2O2 CO CO 2 SO 2 HCl N2N2

26 Paramagnetic Cell Magnet pole pieces Nitrogen filled spheres Feed back coil Suspension & mirror LED source Photocell sensor

27 Paramagnetic Technology Provides: Performance Fast response Exceptional linearity and repeatability High stability & accuracy Economics Long operational life Extractive sample system required Simple validation / calibration Combustion Control: O2 Measurement Detecting air rich conditions

28 Zirconia Oxide Technology Combustion Control: O2 Measurement Detecting air rich conditions

29 At high temperatures, zirconia conducts electricity through the movement of oxygen ions. Heated Chamber Zirconium oxide (zirconia) based techniques Zirconia disk Electrodes Combustion Control: O2 Measurement Detecting air rich conditions

30 0100 Reference Sample C When the oxygen concentration on each side is different, an emf related to oxygen concentration is generated. Nernst Equation Cell output, E = K x Ln ( Pr/ Ps) mV assuming a constant cell temperature Zirconium oxide (zirconia) based techniques Combustion Control: O2 Measurement Detecting air rich conditions

31 Zirconia Oxide Technology Provides: Performance Fast response Unaffected by background gases Sample at hot / wet conditions Economics Very acceptable operational life Low maintenance requirements Simple validation / calibration Combustion Control: O2 Measurement Detecting air rich conditions

32 TDLTechnology

33 Optical Absorption Spectroscopy Based on Beer-Lambert law Used both in UV and IR Typical wideband techniques have low spectral resolution and sensitivity is limited by cross-interference The alternative is single line spectroscopy using tuneable diode lasers (TDL) TDL are available for a range of gases of interest

34 Optical Absorption Spectroscopy Beer Lambert law: T = exp(-Sg(f)NL) – T is transmission – S is the absorption strength – g(f) is the line shape function – N is the concentration of absorbing molecules – L is the optical path length Measuring T and knowing S, g(f) and L, N can be found Use single absorption lines in the NIR

35 Single Line Spectroscopy Gas under test, typical absorption linewidth 0.05 nm Absorption lines from other (background) gases Laser scan range, typically nm, note Laser spectral line width is ca nm UV / IR absorption spectroscopy linewidth > 2 nm

36 Single Line Spectroscopy Choose a single absorption line from available databases Ensure no cross interference from other gases Typical Gas Mix for Waste Incinerator – 10 mg/m 3 HCl – 15% H 2 O – 6% O 2 – 500 mg/m 3 SO 2 – 350 mg/m 3 NO x – 100 mg/m 3 CH 4 – 150 mg/m 3 CO – 10% CO 2

37 Single Line Spectroscopy Laser scan range A single HCl line Absorption spectrum for offgas from waste incinerator

38 Measurement influences Measurement influenced by: – Pressure – Temperature – Background gas composition Just like conventional IR measurements! Due to inter-molecular collisions, which strongly affect the absorption line: – its amplitude – Its width – Its shape (asymmetry) Note: 2f WMS signal is just filtered version of line shape, so all information above is still available (non-linear relations however)

39 Pressure influence – Frequency of collisions increases with gas density i.e. total pressure – Causes line broadening, hence the term “pressure broadening” – Line amplitude (per molecule) is unchanged – Small line centre shift occurs also – Maximum measurement pressure limited by pressure broadening smearing the line so as to overlap an adjacent line Pressure broadening measured for 2f WMS spectroscopy of O2 in N2

40 Temperature influence – Changes gas density and molecular velocity distribution, hence collision frequency and line width – Temperature also changes thermal excitation of molecular vibrations, hence the line amplitude (per molecule) – Can be exploited to distinguish hot gas from cold gas e.g (NEO) oxygen analyser From HITRAN database

41 TDL (Tuneable Diode Laser) Provides: Performance Fast response In-situ measurement at process conditions Temperature and moisture measurement possible Economics Long operational life Low maintenance requirements Inferred validation Combustion Control: O2 Measurement Detecting air rich conditions

42 How can CO be measured? Thick film High accuracy at process conditions Cost effective measurement in combination with O2 Tuneable Diode Laser In-situ analysis Hot, corrosive, particulate latent samples Combustion Control: CO Measurement Detecting breakthrough and flooding

43 Very thin platinum tracks are printed onto a ceramic disk. Combustion Control: CO via Thick Film Sensor

44 Very thin platinum tracks are printed onto a ceramic disk. Combustion Control: CO via Thick Film Sensor These form resistors in a “Wheatstone bridge”, an arrangement that allows small changes in resistance to be accurately detected.

45 Each quadrant is thermally isolated from next by slots. Combustion Control: CO via Thick Film Sensor Very thin platinum tracks are printed onto a ceramic disk. These form resistors in a “Wheatstone bridge”, an arrangement that allows small changes in resistance to be accurately detected.

46 A special catalyst that is selective to CO is then printed over two quadrants Combustion Control: CO via Thick Film Sensor

47 Any CO in the sample will burn on the surface of the catalytic material, creating a change in temperature. CO Combustion Control: CO via Thick Film Sensor

48 CO The change in temperature is detected by the platinum tracks underneath, changing their resistance, which can be detected. Combustion Control: CO via Thick Film Sensor

49 ServoTOUGH Fluegas

50 Servomex Combustion Analyzer History 700 B / N 700 Ex 2700

51 Model 700 Combustion Analyzer Model 700 was introduced circa 1987 Two Models 700B & 700EX Key Features: – Separate sensor head and remote control unit – Oxygen only or with combustibles option – Rugged design (IP55)/wide range of applications – Comprehensive range of probes and filters – Fast dynamic response – Low flow (300 ml) extractive design 700B was discontinued in EX was discontinued in B / N 700 Ex

52 Model 2700 Combustion Analyzer The 2700 was Introduced 1998 Three Models 2700, 2700B & 2700C The 2700C was introduced in 2006 Key Features: – Same basic principal of operation – Standard flame traps – Simple Intuitive User Interface – Auto Calibration and assignable alarm relays – Integral auxiliary air supply – Introduced the TFx combustible sensor for COe – Easy access to servable parts

53 Sensor Head and Remote Controller

54 Auxiliary Air Aspirator Air AutoCal & BlowBack Sample Inlet Aspirator & Sample Outlet Heated Enclosure Flame Trap Internal Filter O 2 Cell COe Sensor Breather Low Flow Extractive Aspirator Flame Trap Solenoid Valve Principal of Operation 2700B

55 Principal of Operation 2700C

56 Servomex Zirconia Cell

57 Sample in Servomex 2700 ZrO2 Zirconia Sensor HeaterReference Air In Platinum Electrodes Zirconia Crucible Diaphragm Springs

58 Servomex Thick Film Sensor  Sample enters and is heated by sensor body  Hot sample reaches sensor and CO combusts - calibrated as CO equivalents (COe) Heater   

59 Heater band PRT Header assembly Sensor housing Outlet Inlet Sensor disc Thick Film Sensor Structure

60 Combustibles Sensor Oxygen Cell Internal filter Flame Trap Aspirator Heater Thick Film Sensor Location

61 Zirconia Sensor Thick Film Sensor Insulated cover keeps wetted components above 210°C Keep it hot = Increase performance. Stop condensation. Stop blockage. Stop corrosion. Increase life.

62 Internal Sample Filter (5 micron) Flame Arrestor (tested by external agency) 2700 Flame Traps and Filter Flame traps prevent risk of sensors igniting unburnt fuel at start up and causing an explosion

63 Modular Design Open, standard filter or large filter Variable lengths, with or without probe retention Wide range of temperatures: <700°C to 1750°C (<1300°F to 3182°F) Special materials eg ceramics or alloys 4” ANSI Standard, 3” ANSI, JIS, DIN, 700B or Thermox flanges 2700 Probes

64 °F Stainless Steel 316 Probe can be used up to 1292F at any probe length Haynes Alloy 556 Probe used for temperatures < 1832F Max temp will be dependent upon probe length High Temperature Ceramic Probe for temperatures < 3182F °C Ceramic Haynes Alloy 556S.S Probes

65 Questions on Analyzer Operation How does the analyzer respond in a low oxygen and /or high combustible conditions? – The analyzer will continue to measure what it sees. The combustible measurement is maintained by the auxiliary air. The oxygen reading is maintained but will be reduced from the true reading by an amount which is dependent on the combustible gas species and concentration. The sensors will not be adversely affected. What are the analyzer/sensor response times? – When installed with a typical probe for heater applications and unfiltered software the T90 response time for oxygen is 10 seconds and 20 seconds for combustibles at 300 ml/min sample rate. Is output signal damping available? – The software allows dampening of both the oxygen and combustible outputs and displays. It can be applied by differing amounts and can be switch out if required. How does the analyzer measure combustibles? – The combustibles analysis is wet and is optimized and calibrated for carbon monoxide to enhance its use for combustion control. The combustibles sensor will respond to most flammable gases apart from methane. Its response to hydrogen is twice that of carbon monoxide.

66 Questions on Analyzer Operation What is the recommended testing frequency? – The initial calibration intervals are 3 months for oxygen and 1 month for combustibles but after operational experience this may typically be extended to 12 months and 2 months What are the known failure modes for the analyzer? – Internal failures Temperature control oxygen Temperature control combustibles Sensor heads Wiring faults Block heater – External failures Aspirator air supply Restricted probe Sensor head temperature – External issues Mounting flange temperature Radiated heat from process Ambient temperature hot and cold

67 Questions on Analyzer Operation What are the common known failure modes for the analyzer? – Loss of sample flow due to probe blockage – Loss of air pressure for aspiration, purging, etc. – Controller power – Sensor head power – Sensor head block heater

68 Best Practice for Installation Serviceable location Ensure ambient temperature is within specifications Protect from wind chill Protect from radiant heat Minimize flange distance from wall to insulation Use correct cable Minimize distance between sensor head and controller Insure proper wiring termination Use probe retention flange when temperature is above 700C Locate utilities in a stable ambient environment Consider blowback for high sulfur high particulate samples Leave sensor head off process until ready to power up

69 ServoTOUGH Laser

70 ServoTOUGH Laser Gas II

71 Dual Modulation Technique Laser wavelength chosen to match absorption line, fine tuning with temperature and current Tune diode laser by temperature to pin-point the centre wavelength of a single absorption line (+/-5mK) Laser wavelength scanned by applying ramp current High frequency modulation added for 2 nd harmonic detection 2 nd harmonic signal extracted by use of mixer CPU computes gas concentration

72 Dual Modulation Technique Diode current Diode laser power Ramp current High freq. modulation ()() (2  ) Detector Process gas Signal processing Temp. contr. Diode laser Det. current Mixer Filter Second harm. Direct signal

73 Differences from conventional IR spectroscopy Laser radiation is monochromatic i.e. a specific wavelength, whereas conventional IR source is “multi-chromatic” Allows TLDS to measure a single absorption line by scanning across it Signal is the line shape or a filtered version of it (2f WMS) Free of cross interfering absorptions if suitable line is chosen i.e. no other lines nearby. Second harmonic WMS, 2 nd derivative of line shape Direct absorption scan

74 Set-up for a in-situ cross stack TDLAS system

75 HARNESS THE POWER OF expertise SERVOTOUGH Combustion Solutions


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